timing of collision of the kohistanladakh arc with india ... of collision of the kohistan–ladakh...

Review ArticleTiming of collision of the Kohistan–Ladakh Arc with India

and Asia: Debateiar_774 308..328

HAFIZ UR REHMAN,1* TETSUZO SENO,2 HIROSHI YAMAMOTO1 AND TAHSEENULLAH KHAN3

1Department of Earth and Environmental Sciences, Graduate School of Science and Engineering, KagoshimaUniversity, Kagoshima 890-0065, Japan (email: [email protected]), 2Earthquake Research Institute,University of Tokyo, Tokyo, Japan; and 3Department of Earth and Environmental Sciences, Bahria University,

Islamabad, Pakistan

Abstract The Kohistan–Ladakh Arc in the Himalaya–Karakoram region represents acomplete section of an oceanic arc where the rocks from mantle to upper crustal levels areexposed. Generally this arc was regarded as of Jurassic–Cretaceous age and was welded toAsia and India by Northern and Southern Sutures respectively. Formation of this arc,timings of its collisions with Asia and India, and position of collision boundaries have alwaysbeen controversial. Most authors consider that the arc collided with Asia first during102–75 Ma and then with India during 55–50 Ma, whereas others suggest that the arccollided with India first at or before 61 Ma, and then the India–arc block collided with Asiaca 50 Ma. Recently published models of the later group leave several geological difficultiessuch as an extremely rapid drifting rate of the Indian Plate (30 � 5 cm/year) northwardsbetween 61–50 Ma, absence of a large ophiolite sequence and accretionary wedge along theNorthern Suture, obduction of ophiolites and blueschists along the Southern Suture, andthe occurrence of a marine depositional environment older than 52 Ma in the Indian Platerocks south of the Southern Suture. We present a review based on geochemical, strati-graphic, structural, and paleomagnetic data to show that collision of the arc with Asiahappened first and with India later.

Key words: Asian Plate, Indian Plate, Kohistan–Ladakh Arc, Northern Suture, SouthernSuture, timing of collision.

INTRODUCTION

The Himalayan mountain range (Fig. 1) is com-posed of a collage of rocks of the Indian and AsianPlates, sandwiching an intra-oceanic Cretaceousisland arc namely the Kohistan–Ladakh Arc(KLA), and represents a classical example ofcontinent–continent collision. The Indian Plateseparated from the Gondwana continent around120 Ma, drifted northward about >4000 km, andcollided with the Asian Plate in the Paleogene withthe closure of the Tethys (Molnar & Tapponnier1975; Klootwijk et al. 1992; Petterson & Treloar2004). The closure of the Tethys and sandwiching

of the KLA between two crustal plates producedtwo major sutures (Fig. 2), which are referred toas the Northern Suture – Main Karakoram Thrust(MKT) – Shyok Suture in the north and the South-ern Suture – Main Mantle thrust (MMT) – IndusSuture in the south.

Timings of collision of the KLA to Asia and India,its obduction and collision-related metamorphism,and the northward drift of the Indian Plate, havebeen discussed previously (e.g. Molnar & Tappon-nier 1975; Tahirkheli et al. 1979; Bard 1983; Patriat& Achache 1984; Klootwijk et al. 1985, 1992;Petterson & Windley 1985, 1991; Pudsey et al.1985; Coward et al. 1986; Pudsey 1986; Beck et al.1995; Rowley 1996; Treloar et al. 1996; Burget al. 1998; Khan et al. 1998; Searle et al. 1999;Arbaret et al. 2000; Yamamoto & Nakamura 2000;

*Correspondence.

Received Received : 4 January 2011; accepted for publication 7 June 2011.

Island Arc (2011) 20, 308–328

© 2011 Blackwell Publishing Asia Pty Ltd doi:10.1111/j.1440-1738.2011.00774.x

Yin &Harrison 2000; Rolland et al. 2002; Yin 2006;Dhuime et al. 2009; Jagoutz et al. 2009; Khan et al.2009; Jagoutz 2010). There are two schools ofthought regarding the timing of collision of theKLA with Asia and India. One school of thoughtfavors the collision of the KLA first with Asiaduring 102–75 Ma, and then with India during55–50 Ma (e.g. Molnar & Tapponnier 1975; Petter-son & Windley 1985; Beck et al. 1995; Rowley 1996;Bignold & Treloar 2003), whereas others favor thecollision of the KLA first with India (ca 95–60 Ma)before its collision with Asia (e.g. Tahirkheli et al.1979; Sharma & Gupta 1983; Schärer et al. 1984;Yin & Harrison 2000; Ding et al. 2005; Yin 2006;Khan et al. 2009). Several authors proposed thepresence of dual subduction system within theNeo-Tethys (Van der Voo et al. 1999), where a sepa-rate intra-oceanic arc system was present, asystem different from that of the KLA–Lhasablock which was docked to India before the finalaccretion of the KLA–Lhasa block to Asia (e.g.Aitchison et al. 2000, 2007).

China

India

Granitic intrusive bodies

Higher Himalayan crystalline

Lesser Himalayan sequence

Siwalik molasse

Legend

Zanskar shelf sediments

Kohistan Arc sequence

N

30 No

25 No

75 Eo

85 Eo

200 km

Pakistan

Fig. 2

5

MBT

MKT

Asian Plate rocks (undiff.)

++

+

+

+

+

+

++ + + +

+

++++

+ +

++

+

+35 N

o

2

MBT

MCT

MMT

1

34

Fig. 1 Location map of the Kohistan–Ladakh Arc (KLA, boxed areamarked as Fig. 2) and the Himalayan Range showing its major tectonicunits. Thick dark lines indicate major tectonic boundaries (MKT, MainKarakoram Thrust, Northern Suture also referred to Shyok Suture orYarlung–Zangbo Suture; MMT, Main Mantle Thrust, Indus Suture orSouthern Suture; MCT, Main Central Thrust; MBT, Main BoundaryThrust). Location of various geological units are shown (�; 1, Hazararegion; 2, Zanskar region; 3, Tingri section; 4, Gamba section; 5, Makranregion; location of the Makran region is extrapolated from a southwesternextension of the Himalayan Range). Map modified after references Bard(1983), Searle et al. (1987), and Rowley (1996).

Kara

kora

m fa

ult

Kohistan

KASHM

IR

K2Gilgit

Peshawar

72° E

75° E

MBT

KKH

MBT

100 km

MCT

N77° E

35° N

LadakhSouthern Suture

Fig. 3.

Fig. 4.

Legend

MBT

MCT

ZSZ (NF)

Southern Suture

Northern Suture

Ophiolite sequence

Karakoram Metamorphic

Complex

Higher Himalayan

Crystalline

Lesser Himalayan

Sequence

Siwalik molasse

Magmatic rocks

Zanskar shelf

sediments (Tethyan unit)

Ultrahigh-pressure eclogites

Blueschists

Karakoram batholith

Hunza

NP

MCT

Rawalpindi

Besham

Asian plate sequence

Indian plate sequence

Kohistan-Ladakh Arc sequence

Northern

Sutu

re

Fig. 2 Simplified geological map of the Northwest Himalaya showing major tectonic units of the Indian Plate, undifferentiated rocks of the Kohistan–Ladakh Arc sequence, and the southern margin of the Asian Plate. Map modified after Bard (1983), Searle et al. (1987), Kaneko et al. (2003), Mahéo et al.(2004), and Petterson & Treloar (2004)). Abbreviations as in Figure 1 (except KKH, Karakoram Highway; NP, Nanga Parbat; ZSZ, Zanskar Shear Zone).

Collision of arc with India and Asia 309

© 2011 Blackwell Publishing Asia Pty Ltd

Timing of collision of the arc with Asia andIndia, formation of the individual lithological units,northward drift of the Indian Plate, and themechanism of construction of the KLA are at thecenter of several controversies. These controver-sies include: (i) position of the stratigraphic bound-ary between the passive margin sequence and theoverlying syn-collision strata of the Tethyan Hima-laya; (ii) size of the absorbed margins along theIndian Plate; and (iii) timing of the collisionbetween India and Asia since two subduction zoneshave been active on both sides of the KLA–Lhasablock at the same time and the southern one is stillactive, as seen from the tomography of the sub-ducted continental lithosphere of the Indian Plate(Van der Voo et al. 1999; Replumaz & Tapponnier2003; Replumaz et al. 2010).

We present a review highlighting the systematicconstruction of the Kohistan–Ladakh Arc system,the position of the forearc and back-arc basins, andthe timing of the collision at the Northern andSouthern Sutures. Our compilation of observationsfrom the field and geochemical, structural, strati-graphic, and paleomagnetic data published in theliterature supports suturing of the KLA with Asiafirst and with India later.

GEOLOGY

ASIAN PLATE SEQUENCE

The Asian Plate sequence (also referred as theKarakoram block) consists of pre-Ordovician crys-talline basement whose Paleozoic history demon-strates its Gondwanan affinity (Gaetani et al.1993). A passive margin associated with theopening of the Tethys Ocean in the Permian toEarly Cretaceous existed (Gaetani & Garzanti1991), which turned into an active continentalmargin of southern Asia in the Early to mid-Cretaceous (Coward et al. 1986; Debon et al. 1987;Searle et al. 1987).

In the Hindu Kush Range of the Chitral area,the Asian mass consists of a sequence of gneisses,slates, and marbles (Fig. 3). These rocks wereassigned the names of Kesu Gneisses, GaheritMarble, and Chitral Slates (Hayden 1916). Theslates extend from the Afghanistan border in thewest to the Mastuj in the east. Above them liemolasse sediments of the Cretaceous Reshun For-mation (red beds and conglomerates) with faultedcontact against Chitral Slates (Pudsey et al. 1985).Amphibolites and serpentinites occur either as

Fig. 3 Structural map showing themajor geological and stratigraphic unitsof the Asian Plate sequence. Map modi-fied from Pudsey et al. (1985), Gaetaniet al. (1993), Zanchi et al. (2000), andHeuberger et al. (2007). For simplicitystratigraphic formation names and localrock units were omitted.

35 30 N

3

6 00 N

3

6 30 N

o'

o'

o'

30 km

71 30 E 72 00 E 72 30 E 73 00 Eo ' o 'o ' o '

KarakoramHindu Kush

ShamranTeru

Mastuj

Chitral

Drosh

Kohistan

China

Pakistan

Arabian Sea

India

Afghanistan

Iran

Tajikistan

Tirich B

ound

ary Z

one

Northe

rn S

uture

Kohistan Arc rocks (undiff.)

Northern Suture melange(greenschists, amphibolites & Purit Fm.)

Karakoram rocks (magmatic batholith, slates, phyllites, shales & Reshun Fm.)

Hindu Kush rocks (magmatic, slates, marbles, amphibolites, serpentinites)

Mesozoic-Tertiary granitoids of the HIndu Kush

Tirich Mir Pluton

Garam Chashma

Pluton

Kafiristan

Pluton

Legend

Reshun Fault

Mirkhani Diorite

N

Kashmir

location of Fig. 3

Reshun

310 H. U. Rehman et al.


massive lenticular bodies or thin schistose shredsalong major faults (Heuberger et al. 2007).However, neither a typical ophiolitic sequence norblueschist facies rocks have ever been found in theNorthern Suture zone (Pudsey et al. 1985; Cowardet al. 1986; Robertson & Collins 2002; Heubergeret al. 2007).

INDIAN PLATE SEQUENCE

Rocks of the Indian Plate sequence, south of theSouthern Suture, are the Higher Himalayancrystalline basement and cover sequences, theLesser Himalayan sequence, and the Siwalikmolasse (Fig. 2). The Higher Himalayan crystal-line sequence mainly consists of pelitic, felsic, andpsammitic schists and gneisses, metacarbonates,and amphibolites with local eclogitic lenses orsheets (Greco et al. 1989; Rehman et al. 2007).The grade of metamorphism increases from stau-rolite to kyanite to sillimanite in schists andgneisses, and from high- to ultrahigh-pressure(UHP) eclogite facies grade in the mafic rocks(O’Brien et al. 2001; Kaneko et al. 2003). The pro-tolith of the Higher Himalayan crystalline felsic–pelitic and calcareous rocks was reported asLower Paleozoic to Triassic whereas the protolithof the basic rocks (amphibolites and eclogites)was reported as Permian (Honegger et al. 1982;Spencer et al. 1995). Eclogite facies metamor-phism in the Tso Morari area (Zanskar region,India) was reported to be 55 � 12 Ma (Sm–Ndand Lu–Hf isochron age; de Sigoyer et al. 2000),and 49 � 6 Ma (Sm–Nd isochron age on garnet–omphacite pair; Tonarini et al. 1993) in thewestern part of Himalaya (Kaghan Valley,Pakistan).

The Indian Plate sequence is separated fromthe KLA by the Southern Suture (Fig. 2). Thissuture is characterized by ophiolitic mélange,blueschists, high-pressure granulites, and UHProcks. Anczkiewicz et al. (2000) reported blue-schists of ca 80 Ma (39Ar–40Ar and Rb–Sr dating onNa-amphibole and white mica) from within theSouthern Suture in the Shangla area (locatedseveral km northwest of Besham; Fig. 2). Theseblueschists were crystallized at temperature�400°C, which is below the closure temperaturefor Ar and Sr exchange in white mica and amphib-ole (closure temperature of white mica forK–Ar = 500°C, Rb–Sr = 600–650°C; closure tem-perature of amphibole for K–Ar = 550–650°Ccalibrated by Villa 1998). Therefore the 80-Maage was considered as a peak blueschist faciesmetamorphism.

KOHISTAN–LADAKH ARC SEQUENCE

The Kohistan–Ladakh Arc, an example of a juve-nile crust, was formed by magmatic addition at anintra-oceanic convergent margin in the Neo-Tethys Ocean (Tahirkheli 1979; Bard 1983; Hamil-ton 1994). It represents a complete section of anoceanic arc where rocks from mantle to uppercrustal volcanic and sedimentary levels areexposed (Fig. 4). Sedimentary sequences (YasinGroup) of Aptian–Albian age (<120–99 Ma) indi-cate that formation of this arc began in the LowerCretaceous (Pudsey 1986). The bulk of igneousinfrastructure formed between 90 and 110 Ma(Schärer et al. 1984; Petterson & Windley 1985).Generally this arc was subdivided into six mainunits (Fig. 4) from bottom to top (south to north):(i) Jijal ultramafic–mafic complex; (ii) Kamila

Fig. 4 Geological sketch mapshowing the major lithological units ofthe Kohistan arc sequence. Map modi-fied after Tahirkheli (1979), Searle et al.(1987), Dhuime et al. (2009), andJagoutz et al. (2009).

Besham

Northern Suture

N

Chalt

Kalam (Utror)

Dir

Southern Suture

ShamranTeru

NP

Legend

Indian Plate

Chilas ultramafic-maficcomplex

Kamila amphibolite belt

Jijal ultramafic-mafic complex

Kohistan-Ladakh batholith & volcanics

The Jaglot & Chalt Group (including Kalam and Dir volcanics)

The Yasin Group

Asian Plate

100 km

Kohistan Gilgit

Ladakh



amphibolites; (iii) Chilas ultramafic–maficcomplex; (iv) Kohistan batholith; (v) Jurassic–Cretaceous metavolcanics and meta-sedimentaryunits of the Jaglot and Chalt Groups, and (vi)Aptian–Albian volcano–sedimentary Yasin Group(Bard 1983; Petterson & Windley 1985, 1991;Pudsey et al. 1985; Pudsey 1986; Treloar et al.1990, 1996; Khan 1994; Dhuime et al. 2009).

Jijal ultramafic–mafic complex

The Jijal complex includes ultramafic rocks (peri-dotites, dunites, pyroxenites) in the lower partand mafic rocks (garnet–granulites with minorpyroxene–granulites/gabbros) in the upper part(Fig. 5). This complex makes a tectonic wedge tothe north of the Southern Suture along the IndusRiver (Jan & Howie 1981; Miller et al. 1991). Yama-moto and Nakamura (2000) assigned an age of118 � 12 Ma (Sm–Nd mineral isochron) to thegranulites of the Jijal complex and associated thisage with its protolith formation. Dhuime et al.(2007) reported formation of the Jijal complexin three stages. They assigned 117 Ma to theultramafic–mafic rocks (stage 1) of the Jijalcomplex, 110 Ma to the pyroxenite dykes (stage 2)of boninitic affinity, and 110–95 Ma to the tholeiiticmagmatism (stage 3).

Kamila amphibolite Belt

This belt is a composite mass dominated byamphibolite facies and is composed of metavolca-nics, ultramafics, gabbros, diorites, tonalites,granites, trondhjemites, and rare siliceous and cal-careous metasediments of Cretaceous to UpperJurassic age (Bard et al. 1980; Treloar et al. 1990;Khan et al. 1993). Treloar et al. (1989) reported a39Ar–40Ar hornblende cooling age of 80 Ma of theamphibolite facies rocks.

Chilas ultramafic–mafic complex

The Chilas ultramafic–mafic complex is domi-nantly made up of gabbronorite (~85%), with somehypersthene–quartz diorite, gabbros, troctolites,anorthosites, pyroxenites, chromite-layereddunites, peridotite, and retrograde amphibolitescomprising the remaining 15% (Khan et al. 1997).A U–Pb zircon age of 84 � 5 Ma was assigned tothe rocks of the Chilas complex (Zeitler et al.1981). Jagoutz et al. (2006, 2009) proposed that thegabbronorite and the ultramafic bodies formed atca 85 Ma.

HHC cover

L. P

aleo

z. -

U. T

rias.

Pre-Ordovician

Gahiret Marble

Chitral slates &gneisses

Reshun Fm

(red beds)

Tria

ssic

U

. Cre

t.-P

al

Kesu gneisses &

slates

(pelitic/felsic schists &

gneisses, calc-shcists &

gneisses, amphibolites,

UHP eclogites)

(granitic gneisses)HHC basement

(metasediments & metavolcanics

of Mid-Jurassic ~ Paleogene)

(117 ~ 95 Ma gfm)

(L. Cretaceous ~ Paleogene

granitoids)

Ophiolite

Jijal ultramafic-mafic complex

(Sapat & Pattan complex?)

Kamila amphibolite belt

Chilas ultramafic-mafic

complex (gabbronorite &

ultramafics of 85 Ma)

Kohistan batholith

Jaglot & Chalt Groups

Yasin Group(Aptian-Albian sediments,

intruded by 150 ~ 102 Ma

Matum das pluton)

(Cret. ~ U. Jur. rocks intruded

by gabbroic plutons, ~ 80 Ma

afm)

basement

Northern Suture

Southern Suture

Indi

an P

late

seq

uenc

eA

sian

Pla

te s

eque

nce

Koh

ista

n-La

dakh

Arc

seq

uenc

e

Fig. 5 Representative section of the Asian Plate, the Kohistan Arc, andthe Indian Plate sequences (not to scale). afm, amphibolite facies meta-morphism; gfm, granulite facies metamorphism. UHP eclogites (�) andblueschists (�) are shown. Lithological units and age values are adoptedfrom Tahirkheli (1979), Pudsey et al. (1985), Petterson & Windley (1991),Khan et al. (1997), Dhuime et al. (2009), and Jagoutz et al. (2009).



Kohistan batholith

The Kohistan batholith is comprised of plutons ofcalc-alkaline gabbros, diorites, granodiorites, andtonalities (Treloar et al. 1996; Jagoutz et al. 2009).Three main stages of magmatism were distin-guished in the Kohistan batholith (Khan et al.1997). Stage 1 plutonism was represented by abimodal series of high-K and low-K high-SiO2

gabbros and diorites, yielding a Rb–Sr whole-rockage of 102 � 12 Ma (Petterson & Windley 1985).These plutons, which are characterized by a pen-etrative ductile deformation, probably predate thesuturing of the KLA to the Asian Plate and belongto the island arc stage. Stage 2 plutons are nor-mally undeformed. A swarm of vertical and unde-formed basic dykes (the Jutal–Numal dykes)cross-cut the structures along the NorthernSuture and the southern margin of Asia. Thesedykes were assigned an age of 75 Ma on the basisof 39Ar–40Ar hornblende age (D. Rex, pers. comm.reported in Petterson & Windley 1985). Severalother stage 2 plutons, intruded in the west ofGilgit, yielded ages of 61–53 Ma and 62–40 Ma onthe basis of the K–Ar method on hornblende andbiotite, respectively (Treloar et al. 1989). Both firstand second stage plutons were intruded by laterstage (34 � 14 and 26 � 1 Ma based on whole rockRb–Sr dating) aplitic and pegmatitic sheets(George et al. 1993).

Heuberger et al. (2007) reported a U–Pb zirconage of 111 � 0.4 Ma from the Mirkhani diorite ofthe Kohistan batholith (Fig. 3), which intrudes theAptian (125–112 Ma) volcanic and sedimentaryrocks of the KLA sequence. Granite dykes offurther younger ages (ca 47 and 37 Ma) whichintrude the diorites and meta-gabbros of theKohistan batholith were also reported by Heu-berger et al. (2007). In addition, Heuberger et al.(2007) determined the Hf isotope composition ofthe rocks of the Asian Plate sequence (Karakoramactive margin unit), the North-Tethys oceanicback-arc basin unit (Northern Suture mélange),and the KLA unit. The Hf isotope compositions(eHf) from these three units, the Asian Platesequence, the Northern Suture zone, andKohistan, range from -1.8 to +4.7, from +5.8 to+14.3, and from +8.2 to +10.9, respectively.

Jaglot and Chalt Groups

The Jaglot Group metasediments and metavolca-nics are exposed in the Thelichi–Gilgit sector of theKarakoram Highway (Figs 1,2 of Yamamoto et al.

2011). This group represents rock assemblages ofback-arc basin origin and includes the Dir-Kalamvolcanics, the Thelichi Formation, the Gashu-Confluence Volcanics, and the Gilgit Formation(Treloar et al. 1996; Khan et al. 1997).

The Dir-Kalam volcanics, exposed in the Dir-Kalam area (Fig. 4), are a sequence of meta-sedimentary rocks (Baraul Banda Slates) andEocene–Oligocene volcanic rocks (Utror VolcanicFormation) (Tahirkheli 1979). The Utror VolcanicFormation is composed of andesite, dacite, rhyo-lite, tuffs, and agglomerates extruded in at leastfive cycles (Tahirkheli 1979). The age of the UtrorVolcanic Formation is not known; however, theyhave a transitional contact with the Baraul BandaSlates. Interbedded limestones with these slatesyielded Thanetian (60.2–54.9 Ma) marine fauna ofMiscellanea micella and Actinosiphon tibeticus(Sullivan et al. 1993).

The Gilgit Formation is composed of gneissesand schists of sedimentary origin and is metamor-phosed to sillimanite grade (Khan et al. 1997).The lower contact of the Gilgit Formation is notexposed; thus its age is not known, and its uppercontact with the Gashu-Confluence Volcanics isalso faulted (Yamamoto et al. 2011). The Gashu-Confluence Volcanics are composed of mafic andcalcareous metamorphic rocks with minormetapelites. This sequence is metamorphosed tolower amphibolite facies. The contact with theoverlying Thelichi Formation is sheared. Sedi-ments of the Jaglot Group indicate turbidite depo-sition in medium to deep-water marine basins(Treloar et al. 1996). The exact age of the JaglotGroup is not known; however, Middle Jurassic toCretaceous is suggested on the basis of Rhabdo-phyllian fauna found in limestone from Kalam area(Bender & Raza 1995).

Petterson and Treloar (2004) divided volcanismin the KLA into two main phases: (i) a phase ofintra-oceanic basaltic and andesitic volcanismnamed the Chalt Volcanic Group; and (ii) a phase ofdominant felsic volcanism named the Shamran Vol-canic Group, also named Teru Volcanic Formationby Khan et al. (2009) (Figs 3,4 show locations).

Phase one volcanics lie unconformably uponthe metasedimentary Jaglot Group (Treloar et al.1996) and are conformably overlain by the YasinGroup (Pudsey 1986). The Chalt Volcanic Groupcomprises Cretaceous to possibly Lower Jurassicpillow volcanics, tuffs, and pyroclastic and minorcalcareous rocks (Petterson et al. 1991; Treloaret al. 1996; Petterson & Treloar 2004). The volca-nics are subduction-related high-Mg tholeiitic



andesites, boninites, calc-alkaline andesites, andrhyolites metamorphosed to greenschist facies(Petterson et al. 1991). Deformation features, suchas tight asymmetric folds with a penetrativebedding-parallel cleavage steeply dipping to thenorth, are commonly observed in the Chalt Volca-nic Group (Petterson & Treloar 2004).

Phase two volcanics are Paleogene and theyinclude highly evolved felsic units. They lie uncon-formably on the steeply dipping Chalt VolcanicGroup and the older parts of the Kohistanbatholith, and are intruded by younger membersof the Kohistan batholith (Danishwar et al. 2001).The 39Ar–40Ar hornblende age of the Teru VolcanicFormation is 58 � 1 Ma (Treloar et al. 1989).Recently Khan et al. (2009) reported a U–Pbzircon age of 64.9 � 0.9 Ma from these volcanics.

Yasin Group

The Yasin Group is comprised of carbonates, andsiliciclastic and volcaniclastic turbidites of Aptian–Albian age (Pudsey 1986). A thick unit of steeplydipping thickly bedded limestone is exposed overthe Chalt Volcanic Group and is further overlainby a thinly bedded, turbiditic, micritic limestoneof similar thickness (Petterson & Treloar 2004).Above them occurs the heterogeneous sequence oftightly folded chlorite-bearing green slates. Theserocks were intruded by a 102-Ma Matum daspluton (Treloar et al. 1989). An age of 150 Ma(zircon U–Pb dating) was also reported from thesame pluton (Schaltegger et al. 2002, 2004).

PREVIOUS TECTONIC MODELS

A number of tectonic models have been presentedwhich describe the tectonic setting of the India–Asia collision and position of the KLA. It is beyondthe scope of the present contribution to present areview of all these models, and here we restrict ourdiscussion to several important models that aredirectly concerned with the collisions that formedthe India–KLA–Asia association; these are mainlyconcerned with the western part of the orogenicsystem.

Pudsey et al. (1985) reported the term NorthernSuture for the western extension of the ShyokSuture (a lineament >1000 km long) separating theAsian Plate from the KLA. Pudsey et al. (1985)carried out extensive field work along the North-ern Suture zone, where the absence of a largeophiolite sequence, accretionary wedges, or blue-

schists let them conclude that the lineament(Northern Suture) indicates the closure of a smallLower Cretaceous marginal basin between theAsian continental plate to the north and the KLAto the south. However, other workers suggestedthat the arc originated by north-dipping subduc-tion of the Tethys Ocean below an intra-oceanic arcin the Early Cretaceous (Coward et al. 1987;Petterson & Windley 1991; Treloar et al. 1996;Burg et al. 1998). The latter interpretation impliesthat there should be a large amount of subduction,possibly northward dipping, which could destroythe Tethyan oceanic basin in order to produce theCretaceous (pre-collisional, ca 90 Ma), Andean-type magmatism along the south Asian margin(Coward et al. 1986; Searle 1991; Searle et al.1987).

Coward et al. (1987) proposed formation of theKLA as a result of accretion of two arcs: a south-ern arc represented by the Jijal complex overlainby the Kamila amphibolites, and a northern arccomprised of the Chilas complex at the base andthe Chalt Volcanic Group in the upper crustallevels. Treloar et al. (1990) considered these twoarcs accreted along the Kamila–Jal shear zone,which represent the most deformed rocks in thesouthern Kohistan.

Debon et al. (1987) supposed partly synchronousclosure by the north-dipping subduction of thetwo Tethyan branches, at the north and southof the KLA. The northern branch very likelyclosed before the southern branch and both wereassumed to have enriched the Karakoram and theKLA intrusives of Cretaceous to Paleogene ages.

Khan (1994) interpreted the tectonic evolutionof the KLA from Lower Cretaceous to Eocene.He considered the Kamila amphibolite Belt as arcmagmatism due to the northward subduction ofthe Neo-Tethyan lithospheric plate. The KLA hada marginal or back-arc basin within which theGilgit zone developed between the Kamila Arczone and the Asian Plate. In that basin two stagesof turbidite (now metamorphosed) deposition tookplace together with volcanics. These volcanicswere derived from the subduction-modified mantlewedge (i.e. the Chalt Volcanic Group). The Chilascomplex formed from magma derived from a meta-somatized mantle diapir, and intruded the back-arcbasin assemblages (Khan 1994).

Treloar et al. (1996) constructed a tectonicmodel on the basis of: (i) timing of volcanic, plu-tonic, and sedimentary events; (ii) the effects ofextensional and compressional magmatic and sedi-mentary processes; and (iii) the arc thickening and



extension associated with the subduction. The firstphase of extension was associated with a back- orintra-arc basin within which Jaglot Group turbid-itic sediments and basalts piled. The second phaseof rifting was related to the emplacement of theChilas complex in an extensional environment.The third phase of extension at about 60 Ma wasreplaced by compression. Following that, riftingoccurred within which the Baraul Banda Slateswere deposited in a forearc rift basin (Sullivanet al. 1993).

Khan et al. (1997) proposed that the crust of theKLA is comprised of the Jijal complex, tholeiiticamphibolites, and tholeiitic to calc-alkaline arc vol-canics (i.e. Chalt Volcanic Group). According tothem the Chilas complex (together with most ofthe Kamila amphibolites) was generated frommantle diapiric rise and emplaced in an intra-oceanic arc–rift setting or in a back-arc basin.Khan et al. (1997) suggested, on the basis of chemi-cal and isotopic compositions, that the ChaltVolcanic Group and Kamila volcanics (nowamphibolitized) formed over a south-dipping sub-duction rather than a northward dipping one. Theyproposed their model based on two pieces of evi-dence: (i) the Chalt Volcanic Group (especiallyinterbedded submarine boninites, and low-Titholeiitic and felsic rocks) formed in a forearcsetting similar to the Izu–Bonin–Mariana forearc;and (ii) the mid-oceanic ridge basalt (MORB)-likeKamila amphibolites probably formed in a back-arc basin (Neo-Tethys) between Karakoram andKohistan. They suggested the formation of KLAat equatorial oceanic regions (Khan et al. 1997,fig. 2.2), which they deduced from the geochemicalsignatures similar to a DUPAL-type magmasource. However, Bignold and Treloar (2003)refuted the idea of DUPAL source and suggestedmixing of a slab-derived component with themantle. A DUPAL source represents a largedomain of oceanic island and oceanic crust basaltswith anomalous Sr, Nd, and Pb isotopic signaturesthat probably existed as mantle entity for billionsof years (Hart 1984). This domain is globally trace-able and continuous around the Southern Hemi-sphere between the equator and 60°S, centered on30 to 40°S (Hart 1984).

Aitchison et al. (2007) suggested that thereexisted intra-oceanic subduction system(s) in theTethyan Ocean before its closure either with Indiaor Asia. They reported the presence of remnantsof an Early to mid-Cretaceous, intra-oceanic arcin the south-facing subduction system within theTethys and considered the Yarlung–Zangbo

Suture zone as the southernmost and youngestamong the sutures which subdivide the TibetanPlateau into several east–west trending blocks.The Lhasa block in the north was separated fromthe Indian Plate in the south through the Yarlung–Zangbo Suture and was represented by a continu-ous, but tectonically disrupted, ophiolite belt(Aitchison et al. 2000). Aitchison et al. (2007)argued that the KLA represents an entirely differ-ent subduction system where the Neo-Tethyanlithosphere was subducted under the southernmargin of Asia. There was another subductionsystem in the Neo-Tethys which consisted of theZedong–Waziristan (Zedong–Luobusa–Dazhuqu–Xigaze–Sangsang–Saga–Jungbwa–Kiogar–Nidar–Spongtang–Waziristan ophiolites) Arc system(for details and locations of the above refer toAitchison et al. 2000, 2007). The rocks of thissystem were thrust southward over the leadingedge of India prior to continent–continent collision(Aitchison et al. 2007). They concluded, based onpaleomagnetic and stratigraphic data, that thecollision of an intra-oceanic arc (located in thesub-equatorial region) with India occurred during55 Ma and with Asia at 35 Ma. Ali and Aitchison(2008) suggested that the central part of the Indiancraton lay at approximately 30°S (the point whichis now at 23.5°N, some 6000 km to the north)during the Late Cretaceous (90–85 Ma), and aftermigrating northwards it collided with Asia in thePaleogene. However, Tan et al. (2010) reportedthat the India–Asia collision occurred at 43 Ma.Their conclusion was based on the paleomagneticdata from the Late Cretaceous red beds of theLhasa block. Tan et al. (2010) reported that thepaleolatitude curves suggest that Greater Indiawas approximately 1500 km away from the Lhasablock at ca 55 Ma, which implies that the LateCretaceous deformation (Takena folding of Allegreet al. 1984) in the Lhasa block and coeval tectonismin the Indian Plate were caused by subduction pro-cesses. This subduction caused the intra-oceanicaccretion of suspect terranes (possibly theZedong–Waziristan Arc system) to the IndianPlate.

Recently, Khan et al. (2009) presented a tectonicmodel emphasizing that the KLA’s collision withIndia occurred first during 64–61 Ma in the equa-torial region >3000 km away from the Asian Plateand the India–KLA block’s collision with Asiaoccurred later during 50 Ma further north. Theirtectonic model was based on: (i) cessation of felsicvolcanism associated with the Teru Volcanic For-mation in the KLA (U–Pb zircon age of 61 Ma),



interpreted as initiation of the India–KLA colli-sion; and (ii) the geochemical characteristics of aDUPAL mantle source assigned to the Teru Volca-nic Formation. They proposed that these volcanicswere formed in the southern hemisphere (inferredfrom the paleoposition of the KLA at 61 Ma).

As can be seen from the above review, the litera-ture is teeming with models with different pro-posals for the timing of the India–Asia collision,position of the subduction system(s), obduction ofthe ophiolitic sequences, and the overall deforma-tional episodes. Controversy remains still. In thisreview, we make it clear (on the bases of structural,geochemical, stratigraphic, and paleomagnetic evi-dence) that the KLA collided with Asia first andwith India later.

FORMATION OF KOHISTAN–LADAKH ARC

We now present major stages of the formation ofthe KLA (Fig. 6). The oldest known magmaticactivity in the KLA was possibly the formationof the Matum das pluton (ca 150 Ma) in a rift-related extension environment represented by anextremely depleted oceanic magmatic componentin the Tethys crust (Schaltegger et al. 2002).

The start of the subduction processes is markedby the formation of the ultramafic–mafic Jijalcomplex. Dhuime et al. (2007, 2009) suggested thatthe mafic–ultramafic rocks of the Jijal complexwere formed from a two-component origin(recycled sediment � subducted altered oceaniccrust) during the initiation of subduction of theIndian Plate oceanic lithosphere. Their assigningof a two-component source to the Jijal complex wasbased on isotopic signatures of the Jijal gabbros,coupled with strong negative anomalies in the highfield strength elements and fluid mobile elementenrichment. Moreover, they considered stage 1 ofthe Jijal complex (ca 117 Ma) as the initiation ofthe subduction within the Neo-Tethys at a slow-spreading mid-ocean ridge, along a transform orfracture zone where the older lithosphere sankbeneath the younger one. Following that the stage2 dykes of boninitic affinity sealed the stage 1 mag-matic episode. Finally, stage 3 plutonism occurred,which was the stage of mature arc formation.Geochemically, stage 3 plutons have a strikinglyhomogenous depleted MORB mantle with low Srand high Nd ratio – enriched mantle componentwith high Pb and Sr ratio and intermediate Ndratio (DMM-EM2; Zindler & Hart 1986) isotopesignature and a pronounced enriched mantle

200 150 100 50 0 Ma

Triassic Jurassic Cretaceous Paleogene Neogene Qtr.

L M U L U Pal Eoc Oli Mio Pli

Matum das pluton

Yasin Group????

Teru volcanics (Phase 2)

(Shamran volcanics)Chalt volcanics (Phase 1)

?? ??

Jaglot Group?? ??

Utror volcanics

Kohistan Batholith

Chilas complex

Kamila amphibolites??

Jijal complex

Blueschists

(Shangla)

Eclogites & UHP rocks

Oceanic sedimentation

(rift-related extension)

Intra-oceanic arc

formation

Obduction of ophi-

olites & blueschists

KLA-Asia

contact

KLA-India

contact

Stage 1 Stage 2 Stage 3

199.6 145.5 65.5 23.0 2.6Southern sutureNorthern suture

Fig. 6 Illustration showing main lithological units of the KLA, and its timing of collision with Asia and India. For simplicity and due to largeruncertainties, the time events for the possible accretion of minor blocks to India are not plotted. Geological time intervals and terms used are adopted afterthe International Stratigraphic Chart of the International Commission on Stratigraphy (ISC, 2009). Major tectonic events are detailed in the text.



(EM2) contribution from the slab component(Dhuime et al. 2007).

The magmatic activity in an intra-oceanic settingduring the Cretaceous to Upper Jurassic (Bardet al. 1980; Treloar et al. 1990), represented by theprotolith of the Kamila amphibolites and theirtypical subduction-related environment (Khanet al. 1997), indicate its formation either before orcoeval with the formation of the Jijal complex.However, their hornblende 39Ar–40Ar cooling agesindicate that regional amphibolite facies conditionsexisted prior to 80 Ma (Treloar et al. 1989).

In the next stage, the Chilas complex formed ca85 Ma. Jagoutz et al. (2006, 2009) suggested thatthe Chilas complex was formed due to an intra-arc extension with decompression melting. Thegeochemical and Nd-isotopic data of the Chilasgabbronorite and the enclosed ultramafic bodiesindicate that the melt parental to the gabbronoritesequence formed the dunite cores of the ultramaficbodies which have intruded and alimented the gab-bronorite during their replace-channeled intrusiveprocess (Jagoutz et al. 2006).

The Kohistan batholith formed from variousplutons (earlier section) over 70 my in a variety oftectonic environments. The penetrative ductiledeformation preserved in the first stage of plu-tonism (ca 102 Ma) in the Kohistan batholith(Petterson & Windley 1985) predate the suturingof the KLA to the Asian Plate. The undeformedplutons (stage 2 of younger than ca 75 Ma) haveprobably developed during an Andean-type set-upfollowing the Upper Cretaceous suturing of theKLA to the Karakoram block but predate theEocene KLA collision with the Indian Plate (Petter-son & Windley 1985; Khan et al. 1997). Stage 3plutons (<40 Ma) postdate the collision of India withthe KLA. The 87Sr/86Sr initial ratio and garnet–muscovite mineralogy of the aplitic and pegmatiticsheets of the Gilgit–Chalt segment suggest theirformation from partial melting of the crustal mate-rial (Petterson & Windley 1985). However, Jagoutzet al. (2009), on the basis of geochemical data andage dating, concluded that the formation of grani-toids of the Kohistan batholith was a continuousprocess which lasted from 112 to 38 Ma. Theyargued that these granitoids were formed as aresult of fractional crystallization of a mantle-derived melt because of the negative correlationbetween Mg# and SiO2 and a high Ni content(approximately 50 ppm), and refuted the idea ofpartial melting for the Kohistan batholith.

The Hf isotope compositions (eHf) from theKohistan (+5.8 to +14.3) and Karakoram (-1.8 to

+4.7) batholiths and from the Northern Suturezone (+8.2 to +10.9) represent intermediate valuesbetween continental crust signature (-10 <eHf < -20; Vervoot et al. 1996, 1999) and a depletedmantle signature (+15 < eHf < +25; Patchett & Tat-sumoto 1980; Nowell et al. 1998; Chauvel &Blichert-Toft 2001). The eHf values from the threedistinct units showed an apparent increase fromthe Asian Plate (Karakoram) through the suture tothe Kohistan (see fig. 27 of Heuberger et al. 2007).The eHf values (+9.4 to +11.6) of the younger intru-sive of the Kohistan batholith (ca 50–39 Ma; Heu-berger et al. 2007) point to a less depleted meltsource than MORB-type mantle. The Hf isotopecompositions represented a varying melt composi-tion somewhere between a crustal end-memberand a depleted (MORB-type) mantle-source,hence fitting a continental margin setting. Thatis why the eHf values of the Karakoram andKohistan batholiths are in the same range of +2to +11. The eHf of +10 from the only true suturezone sample (basalt sill of 107 Ma) represented thesubduction-related magmatism at the Asian Plate(Karakoram margin). Heuberger et al. (2007) con-cluded, on the basis of deformation and the 47-Maage of granite dykes of the Kohistan batholith, thatthe magmatic and tectonic activity continued untilthe Eocene.

GEOLOGICAL EVIDENCE

TIMING OF COLLISION OF KOHISTAN WITH ASIAAND INDIA

The timing of the collision of the KLA with Asiaand India can be deduced from: (i) deformationalfeatures along the Northern Suture zone; (ii)ending of marine sedimentation in the SouthernSuture zone; (iii) paleomagnetic records preservedin rocks of the KLA, the Indian Plate, and theAsian Plate; (iv) drifting rate of the Indian Platetowards the north; (v) position of the collision con-tacts; and (vi) the geochemical constraints on thecollision contacts.

Timing of the collision along Northern Suture

Zanchi et al. (2000) reported that closure of theNeo-Tethys oceanic crust was in the mid-Cretaceous. During the Cretaceous the Asianmass suffered severe deformation combined withintensive intrusive plutonic activity due to thenorthward subduction of the Neo-Tethys oceanic



crust below Asia. Folds and thrust sheets weresealed by the mid-Cretaceous Reshun Formation(Gaetani et al. 1993). This deformational eventmarks the closure of the Northern Suture, which isrepresented by a final accretion of the KLA toAsia. Thus the deposition of the Reshun Formation(in the Chitral area) can be regarded as coeval withthe closure of the Northern Suture. Similarly, inthe Gilgit area (east of Chitral) the timing ofclosure of the Northern Suture can be inferredfrom the reported age (75 Ma) of the Jutal–Numaldykes (Petterson & Windley 1985) which cross-cutthe structures along the Northern Suture and thesouthern margin of Asia. The timing of collisionalong the Northern Suture can also be determinedby the age of volcanism in the KLA. Petterson andTreloar (2004) suggested that the phase one volca-nism in the KLA (Chalt Volcanic Group) predatesthe suturing of the KLA to Asia, whereas thephase two volcanism (Teru Volcanic Formation)postdates it. Therefore, the suturing of the KLAwith Asia could not be younger than the age of theTeru Volcanic Formation ca 61 Ma. The secondphase, according to them, continued after the ini-tiation of subduction of the Indian Plate continen-tal crust. Deformation features such as tightasymmetric folds and bedding-parallel cleavage inthe Chalt Volcanic Group indicate suturing of thearc to Asia.

Timing of collision along Southern Suture

The timing of the collision along the SouthernSuture can be inferred from the sedimentary for-mations exposed along the sedimentary basinssouth of the Southern Suture and their strati-graphic ages. In this section we discuss types ofsediments, their depositional environments, andthe ages of various stratigraphic formationsexposed along the southern margin of the IndianPlate south of the Southern Suture. They includethe Gamba and Tingri regions in the easternHimalaya, Zanskar region in the central Hima-laya, Hazara region in the western Himalaya, andMakran region in the south western tip of Hima-laya (Fig. 1 shows locations).

In the eastern Himalaya (Gamba and Tingri sec-tions), Upper Cretaceous to Paleogene units arecompletely conformable. The molasse sedimenta-tion along the Tibetan part of the suture zone wasregarded as Eocene. Similarly, the initiation ofdeposition of molasse at the Southern Suture wasalso regarded as Eocene (Searle et al. 1987). In thecentral Himalaya (Zanskar region) Gaetani and

Garzanti (1991) reported Prussian (50.7 Ma)marine sediments of the Tethyan continentalmargin (Chulung La and Kong Kesi Formations)south of the Southern Suture. Similarly, in thewestern Himalaya (Hazara region) Bossart andOttiger (1989) reported marine sediments of thelate Thanitian (Lockhart Limestone) and earlyYpresian (Patala Formation) from the LesserHimalayan sequence which underlie Balakot For-mation (flysch sediments), south of the SouthernSuture. These formations represent a transitionfrom shelf to foredeep environment and thussupport the collision of the Indian Plate with theKLA in the Ypresian. Najman et al. (2001),however, refined the age of flysch sediments of theBalakot Formation to be 36–40 Ma (based onthe 39Ar–40Ar method on white mica). Moreover, inthe Makran region, the southwestern extensionof the Himalaya (Fig. 1), Allemann (1979) reportedan Eocene fauna (Miscellanea miscella; 52 Ma)from the limestone (Murree Brewery Limestoneof the Tethyan shelf sediments near Quetta), whichindicate the presence of a marine environment.The cessation of marine sedimentation along theIndian northern margin thus occurred at 52 Ma,and the foredeep sedimentation in both theZanskar and Hazara basins was continuous belowthe middle Ypresian and terminated in theLutetian ca 49.0–45.7 Ma (Rowley 1996).

The sedimentological evidence explained aboveindicates that the collision of the KLA with Indiacould not have been older than the middle Ypre-sian ca 50.7 Ma, because passive margin sedimen-tation (Chulung La Formation in the Zanskar areaand the Balakot Formation in the western part ofHimalaya), in the Hazara area occurred along thenorthern margin of India (Fig. 1). The passivemargin sedimentation in the Zanskar region iscontinuous below middle Ypresian (Gaetani & Gar-zanti 1991). Support for a post-Ypresian (<50 Ma)India–KLA collision is also seen in the Hazara area(36–40-Ma Balakot Formation and its unconform-able contact with the underlying early YpresianPatala Formation; Najman et al. 2001).

Rowley (1996) suggested, based on the sedimen-tary environments and stratigraphic position ofthe Hemis conglomerate and the Nurla Formation(alluvial fan deposits) and the Nimu Formation(lacustrine sediments) located south of the South-ern Suture, that the final collision of the KLA withIndia was post-early Eocene (<40 Ma). Theirobservation is consistent with the stratigraphy ofthe Zanskar region further to the south, with theEocene molasse sedimentation along the Tibetan



part of the suture zone, and along the SouthernSuture (Searle et al. 1987). The presence of Mis-cellanea miscella from the Tethyan shelf sedi-ments in the Makran region, south westernextension of Himalaya (Allemann 1979) also sug-gests a marine environment during Eocene time(>52 Ma) at the Indian northern margin, whichindicates that India and the KLA were not incontact at that time.

PALEOMAGNETIC RECORDS

To estimate the closure time and position of eachtectonic block we show paleomagnetic data fromthe rocks of the KLA, and Indian and Asian Plates.First, we discuss paleomagnetic records from theAsian Plate. Zaman and Torii (1999) reportedpaleomagnetic data from the Cretaceous red bedsamples of eastern Hindu Kush (a geographicalname comprising the Asian Plate). They deducedthree components of magnetization recorded inrocks of the Asian Plate and in the NorthernSuture zone. Component 1 recorded in Asian rockswas unstable and represented the local presentfield direction, Component 2 from the NorthernSuture zone was secondary (KLA–Asia colli-sion-related authigenic remagnetization), andComponent 3 was the characteristic remanentmagnetization (ChRM). They concluded that theChRMs from the Asian Plate (Karakoram) wereacquired at equatorial to low southern or lownorthern paleolatitudes (2.2°S and 1.1°N) duringthe mid- to Upper Cretaceous. Zaman and Torii(1999) inferred that the red bed sediments of theKohistan–Karakoram composite unit were depos-ited after the arc–continent collision along theNorthern Suture in the mid to Upper Cretaceous.This indicates that the Cretaceous configuration ofAsia (Kohistan–Karakoram composite unit) wasnot far from the southern margin of Asia duringthe Cretaceous. The identical inclinations acrossthe Northern Suture also indicate that suturingwas complete at the time of ChRM acquisition(mid- to Upper Cretaceous ca 102–85 Ma).

Now we show paleomagnetic data from the KLAand Lhasa block (Tibet). Ahmed et al. (2000)reported paleomagnetic results of the Utror Volca-nic Formation exposed in the southern part of theKLA (Fig. 4). They reported two components ofnatural remanent magnetization from these volca-nics. The ChRM from the Utror Volcanic Forma-tion was acquired at 12°N.

Ahmed et al. (2001) also reported rock-magnetic and paleomagnetic results of the Paleo-

gene volcanic (Teru Volcanic Formation) andplutonic rocks exposed in the northern part of theKLA (Fig. 4 shows location). They reported twocomponents of magnetic behavior in volcanics.The plutonic rocks also showed geographic coor-dinates similar to those of volcanics. The ChRMof volcanics showed post-tilting remanent magne-tization. The plutonic rocks also showed the samedirections. Therefore, the volcanics were remag-netized at the time of intrusive activity or bothvolcanic and intrusive rocks have suffered thesame remagnetization (Ahmed et al. 2001). Themagnetic declinations from the Teru Volcanic For-mation produced paleolatitudes of 27.5 � 6°N andthe mean ChRM of intrusives yielded paleolati-tudes of 22.4°N.

For comparing the paleomagnetic records of theKLA with its eastern equivalent (Lhasa block), wediscuss data from the Lower Cretaceous (Aptian–Albian red beds located north of the Indus–Yarlung–Zangbo Suture or Southern Suture).Patriat and Achache (1984) reported that southernTibet was located at paleolatitudes of 11.5 � 3°Nand the remanent magnetization recorded in theLadakh (KLA) intrusives before 50 Ma showedpaleolatitudes between 7 and 10°N. Recently, Tanet al. (2010) reported that the Late Cretaceous redbeds from the Lhasa block were located at 23.5°N.In contrast, Abrajevitch et al. (2005) reportedthat the Dazhuqu terrane (part of the Zedong–Waziristan intra-oceanic arc system in the Tethys)was located at 1–8°N paleolatitudes during Creta-ceous time. This indicates a substantial distancebetween the Dazhuqu terrane and the Lhasablock. Based on these paleomagnetic results, Tanet al. (2010) concluded that the collision of Indiawith the Lhasa block occurred at 43 Ma at pale-olatitudes of 21–27°N. The paleolatitudes at11.5 � 3°N of Lhasa block in the Lower Creta-ceous and the remanent magnetization records ofthe KLA intrusives at paleolatitudes 7–10°Nbefore 50 Ma (Patriat & Achache 1984) indicatethat the KLA was almost in the same latitudinalposition as the Lhasa block.

Aitchison et al. (2007) compiled literature dataon the paleoposition of the Asian mass. Theysuggested that the Gangdese batholith and Lin-zizhong volcanics were components of the mag-matic arc that developed in response to subductionof Neo-Tethyan oceanic lithosphere beneath thesouthern margin of Asia. They mentioned that thecontact of India with the Lhasa block at 55 Ma, orany time before, would appear physically impos-sible as the two margins of the blocks involved in



the orogeny were nowhere near each other at thattime. Aitchison et al. (2007) suggested the timingof collision along the Southern Suture to be latestEocene or younger (�35 Ma). They also men-tioned that the KLA collided with Asia well beforethe closure of Neo-Tethys (because the KLA–Lhasa block is a separate arc system from theZedong–Waziristan arc system), and the completeclosure of the Tethys occurred at or after 35 Ma(further details in Aitchison et al. 2007). In thewestern part of the Himalaya (Pakistan), Dargaiand Waziristan ophiolites are so far considered asthe continuation of KLA. However, based onAitchison et al.’s (2007) observations on the struc-tures in the eastern Himalaya, the tomography ofthe subducted continental lithosphere of theIndian Plate showing a dual subduction system(e.g. Van der Voo et al. 1999; Replumaz & Tappon-nier 2003), and our observations in the field andother literature data, we suggest that the KLA isthe western equivalent of the Lhasa block and ispossibly different from the Dargai and Waziristanophiolites. The Dargai ophiolite is an ophiolitesequence which overrides the Indian Plate some30 km south of the Southern Suture (Jan et al.1993).

Khan et al. (2009) argued, based on the paleo-magnetic data of Ahmed et al. (2000), that theChRM from the Utror Volcanic Formation wasacquired during the later stages of deformation,but before the deformation was complete. ThisChRM was acquired at 12.8 � 4.5°N, and evenafter unfolding these declinations the scatter inthem was negligible. Thus, Khan et al. (2009) pro-posed a latitude slightly less than 12°N for ChRMsacquisition of the Utror Volcanic Formation. Khanet al. (2009) concluded that the northern margin ofIndia was near the equator at 60 Ma and reached10°N before 50 Ma, and that the collision of theKLA with India was before 50 Ma at latitudesclose to the equator.

Now we show paleomagnetic data from theIndian Plate. Patriat and Achache (1984) reportedmotion of the Indian Plate compared with thesouthern margin of the Asian Plate based on datafrom the marine magnetic anomalies in thecentral Indian Ocean. They showed that north-wards motion of the Indian Plate was 15–20 cm/year until anomaly 23 (52 Ma), then it slowed to<10 cm/year between anomalies 23 to 13 (36 Ma),finally from anomaly 13 to the present it resumednormal and stable northward convergence withrespect to the Asian Plate at a constant rate of<5 cm/year.

Besse et al. (1984) reported paleomagnetic datafrom the Cenozoic shallow marine sediments (theDingri Formation, which is mainly comprised oflimestone rich in foraminifera and reddish fine-grained sandstone) deposited along the northernmargin of India. The depositional age of the DingriFormation was reported to be 57 � 1 Ma, based onaccurate biostratigraphy (details in Besse et al.1984). On the basis of the apparent polar wanderpath (APWP), Besse et al. (1984) constructed thelatitudinal history of the Dingri Formation, basedon which they concluded that an age older than57 Ma (deposition at Dingri) for closure along theSouthern Suture is geologically impossible. Besseet al. (1984) proposed that age of the collision waslikely to be between 53 and 47 Ma based on theirassumption of the amount of convergence alongthe major thrusts south of the Southern Suture.Thus, they concluded that a 50-Ma age for theclosure/collision of India along the SouthernSuture was the most favorable because it was thetime when a sudden slow-down (representing acollision) in the northward drift of the Indian Platewas observed. Their data from anomaly 22 (50 Ma)is also consistent with the interpretation of Patriatand Achache (1984).

NORTHWARDS DRIFT RATE OF INDIAN PLATE

Khan et al. (2009) reported that the KLA first col-lided with India and at that time it was more than3000 km from the southern margin of Asia. Theymentioned that India has moved rapidly north-wards passing the equator at 60 Ma and reached10°N before 50 Ma. The latitudinal distancecovered by India calculated with reference to theAPWPs from India (Klootwijk et al. 1985, table 2)indicates that the northward drift of India wasrapid during 60–50 Ma (40.5–57.5°S; polar lati-tude). Between 50 and 40 Ma, it covered 10° (57.5–67.5°S; polar latitude) compared to the 17° driftbetween 60 and 50 Ma, which shows a slow-down inthe northward drift of the Indian Plate. Guillotet al. (2003) reported that the northward drift ofthe Indian Plate was 18 � 5 cm/year during65–55 Ma and it slowed to 10 � 2 cm/year during55–49 Ma. Similarly, Acton (1999) calculated therate of APWPs along the paleomagnetic Eulerpole track and reported three major rate changes(and four rates) in the northward drift of India:6.6 cm/year between 120 and 73 Ma, 21.1 cm/yearbetween 73 and 57 Ma, 9.5 cm/year between 57 and20 Ma, and 1.1 cm/year from 20 Ma to the present.Therefore, even the maximum drifting rate of



23 cm/year by Guillot et al. (2003) can not consumethe 3000 km distance between the KLA and Asiawithin 10 my. The northward drift rate of theIndian Plate according to these studies is there-fore not consistent with Khan et al.’s (2009) data ofthe rapid northward drift of the India and KLA.

The northward drift of the Indian Plate and itscollision with the KLA and Asia can also be con-strained from the paleomagnetic data. As we knowfrom the literature data (Patzelt et al. 1996; Besse& Courtillot 2002) the northern margin of theIndian Plate was situated at paleolatitudes of5.7 � 4.4°S during the Cretaceous (ca 67.7 Ma),the Dazhuqu terrane (part of the Zedong–Waziristan Arc system) was located at paleolati-tudes of 1–8°N during the Cretaceous (Abrajevitchet al. 2005), and the Lhasa block and KLA werelocated at paleolatitudes of 21–27°N (Tan et al.2010) and 12°N (the Utror Volcanic Formation;Ahmed et al. 2001) respectively. Tan et al. (2010)pointed out that if the Dazhuqu terrane (part ofthe Zedong–Waziristan Arc system) remained atthe same paleolatitudes the accretion of this intra-oceanic arc system to the northern margin of Indiacould happen between 70 and 60 Ma. However, thepaleolatitudes from the Lhasa block (21–27°N; Tanet al. 2010) suggest that the Dazhuqu terrane andthe Lhasa block were far apart from each otheruntil ca 55 Ma. Similarly, in the west the paleolati-tudes from the northern margin of India and fromthe KLA (Utror Volcanics) also show that theywere far apart from each other. This clearly indi-cates that the collision of India with the KLA hadnot yet occurred.

POSITION OF COLLISION CONTACTS

If we consider the collision of the KLA first withIndia in the equatorial region at 61 Ma, and thecollision of the India–KLA block with Asia (30°further north) at 50 Ma as proposed by Khan et al.(2009), it is impossible to obtain the above geo-graphic distribution from the paleomagnetic datathey used. In Figure 7 we plot the paleolatitudes vsage for India, KLA, and Asia from the data theyused (for simplicity and due to larger uncertaintieswe ignore the possible accretion of minor blocks toIndia). For India, Khan et al. (2009) used the dataof Besse and Courtillot (2002) and Schettino andScotese (2005). For the KLA, they used the pale-olatitude of 12.8 � 4.5°N of the Utror Volcanic For-mation (located in the southern part of theKohistan Arc) and of 27.5 � 6°N of the Teru Volca-nic Formation (located in the northern part of theKohistan arc: grey dashed-lines with arrows). Theages of acquisition of the remanent magnetizationof these volcanics are not known. However, Khanet al. (2009) inferred that the magnetization for theUtror and Teru Formations was acquired before 50and 30 Ma, respectively. Although this inference iscorrect in the sense that the KLA was located tothe north of India, we can not precisely constrainthe ages of the magnetization of these volcanics.We can only say that magnetization occurred aftervolcanic eruptions (61–65 Ma for the Teru VolcanicFormation). Therefore, the arrows are only drawnfor the period younger than 65 Ma. Althoughseveral authors considered the Utror VolcanicFormation as equivalent to the Teru Volcanic

Fig. 7 Correlation diagram of age vspaleolatitudes for India (�), KLA (greydashed arrows) and Asia (grey bar)based on the paleomagnetic data usedby Khan et al. (2009). Present location ofthe KLA (�) is sown. Dashed thinbroken and dark thick lines show thetrajectories of the KLA as proposed byKhan et al. (2009) and this study,respectively. For details refer to the textabove.

x

x

x

60 40 200

20

40

N

80 100 120 Ma 0

Asia

KLA

IndiaUtor

Teru

ChilasJutal-Numal

Jijal

o

o

o

x

20o



Formation (e.g. Khan et al. 2009 and referencestherein) recent results show that they are prob-ably older than the Teru Volcanic Formationbecause they are intruded by granitoids older than70 Ma (Jagoutz et al. 2009). The paleolatitude forthe southern margin of Asia cited by Khan et al.(2009) is also plotted (grey bar). If we accept atraveling path of the KLA like Khan et al.’s (2009)model, the paleomagnetic data of India indicatethat the KLA should have been separated fromIndia and traveled faster to the north than India,as shown by the thin broken line in Figure 7.Admitting that the locations of the KLA can beanywhere in the dashed lines with arrows, we cannot conclude that the KLA and India were weldedat about 61 Ma and traveled together to about30°N during the succeeding 10 my.

We note that deriving a model for the India–KLA collision first and their collision with Asialater, based on assumptions such as: (i) the young-est age of the Teru Volcanic Formation (61 Ma) ascessation of volcanism due to collision with India;(ii) location of the KLA in the southern hemisphere(DUPAL anomaly); and (iii) closure of the North-ern Suture at 50 Ma as proposed by Khan et al.(2009) and several other authors, would require anorthward India–KLA drifting rate of approxi-mately 30 � 5 cm/year. Since no such speed isknown for either modern or historical platemotions, it is doubtful that driving forces such asslab pull and ridge push can provide such a highspeed. The drifting rate of the Indian Plate shownin Figure 6 is approximately 10 cm/year between60 and 50 Ma (Besse & Courtillot 2002; Schettino& Scotese 2005). Because India traveled togetherwith the KLA since ca 61 Ma, we review otherpaleomagnetic data for the rate of the drift of theIndian Plate (e.g. marine magnetic anomalies inthe central Indian Ocean by Patriat & Achache1984; Indian APWPs by Klootwijk et al. 1994;Acton 1999; India–Asia convergence rates from anumber of references summarized by Guillot et al.2003; and Indian craton motion paths summarizedfrom various references by Aitchison et al. 2007).The highest drifting rate among these studiesduring the period concerned is approximately20 cm/year, and can not yet consume the 3000 kmdistance between India–KLA and Asia within10 my.

GEOCHEMICAL CONSTRAINTS ON COLLISION CONTACTS

The proposal that a DUPAL source for theKohistan Arc based on Pb isotope values of the

Teru Volcanic Formation (higher with respect tonorthern hemisphere reference line; Khan et al.2009) could be correct. However, mixing of a slab-derived component with the mantle is also pos-sible. Therefore, assigning an earlier collision ofthe KLA with India before its collision with Asia onthe basis of isotope ratios has a weak evidentialbasis. Moreover, the DUPAL mantle source of theTeru Volcanic Formation does not necessarilymean that the collision of the KLA with India pre-ceded its collision with Asia. The emplacement(85 Ma) of the Chilas complex and the formation ofthe Northern Suture (75 Ma) close to the Asiancontinental margin suggest that the KLA hadreached Asia much earlier than 61 Ma (Fig. 7,thick black line). On the other hand, this earliercollision of the KLA with Asia contradicts the pale-olatitude of the Utror Volcanic Formation becausethese volcanics were always located in the south-ern part of the KLA (Fig. 7).

Khan et al. 2009 postulation of KLA’s collisionwith India prior to its collision with Asia was sup-ported by the geochemical study of the granitoidsin the Chilas complex (major and trace elementchemistry and U–Pb zircon age) of the KohistanArc (Jagoutz 2010). However, Jagoutz et al. (2009)suggested that Kohistan was an intra-oceanic arcthat was formed from the fractional crystallizationof mantle-derived melt as a continuous processbetween 112 and 38 Ma.

The geochemical (trace element and Sm–Ndisotope) data from the Ladakh Arc (Kardung Vol-canic Formation and Dras 1 Volcanic Formation,exposed in the Southern Suture zone in Ladakh)and the trace element chemistry of sedimentsdeposited in the forearc basins of the KLA clearlymark the transition between pre- and post-collisional timing of the joining of the arc to Asia(Clift et al. 2002). Clift et al. (2002) proposed aCampanian–Maastrichtian age (85–65 Ma) as theminimum age of the Dras–Asia collision. However,the Aptian–Cenomanian (119–90 Ma) age of theNaktul Formation does predate the collisionbecause these lavas show more depleted, lessradiogenic geochemistry (Clift et al. 2002), andthus are mainly of intra-oceanic origin. Based onthe results from geochemical work on the KLAvolcanics, sedimentary rocks, and the strati-graphic positions (Clift et al. 2002 and referencestherein), the age of the collision of the KLA withAsia was reported between 83.5 and 93.5 Ma(Berggren et al. 1995). This estimate is also consis-tent with the age proposed by Searle (1991)inferred from the Jutal–Numal dykes. Clift et al.



(2002) on the basis of their geochemical work con-cluded that the Dras 1 Volcanic Formation wasdeveloped in an oceanic setting, but was close to alarge continental mass (Asia?) which was continu-ously providing sediment influx.

SUMMARY AND CONCLUSION

1 By a careful review of literature, and includinggeochemical, geophysical and field observations,we present a tectonic model which best fits thetectonic scenario of the India–Asia collision(Figs 6,7). We point out that the model proposedby several authors (e.g. Khan et al. 2009 andreferences therein) implies an extremely rapidnorthwards-drifting rate of the Indian Plate ofapproximately 30 � 5 cm/yr between 61–50 Ma,which seems geophysically too high and is notconsistent with other existing paleomagneticdata from India.

2 Initiation of subduction of the Neo-Tethys andemplacement of the Jijal ultramafic–maficcomplex at 118–95 Ma (Fig. 6) would require ca60 my to subduct an ocean south of the KLAprior to the India–KLA collision, if this collisionhappened at 61 Ma as proposed previously. Theconvergence rate then would have been veryslow before the India–KLA collision, whereas itwas extremely rapid until 50 Ma in order toconsume >3000 km of the Tethyan oceanic crustbeneath Asia. It is difficult to imagine such adrastic change in the convergence rate for avail-able plate driving forces such as slab pull andridge push.

3 We deduce that suturing of the KLA to Asiacould not be younger than the age of the Teruvolcanics ca 61 Ma, because the Jaglot Groupmetasediments and metavolcanics which areintruded by the Teru volcanics were metamor-phosed and deformed due to the closure of theNorthern Suture. The reported presence of75 Ma Jutal–Numal dykes, which cross-cut thestructures along the Northern Suture and thesouthern margin of Asia, are in good agreementwith our interpretation of the KLA’s earliercontact with Asia. In addition, the Cretaceousconfiguration of Asia and the KLA at paleolati-tudes of 2.2°S and 1.1°N (Zaman & Torii 1999)and the magnetic inclination across the North-ern Suture also suggest that the KLA and Asiawere not far from each other at the time ofacquisition of the magnetic inclinations duringthe mid- to Upper Cretaceous (102–85 Ma).

4 The absence of blueschists and UHP rocks alongthe Northern Suture, the presence of 80-Mablueschists as a consequence of the subductionof the Tethyan lithosphere beneath Asia, and theobduction of ophiolites prior to 65 Ma along theSouthern Suture (Anczkiewicz et al. 2000) pre-clude early collision between the KLA and India.Additionally, the Eocene eclogite facies meta-morphism was related to the subduction of theIndian Plate continental lithosphere beneath theKLA. Since the Southern Suture was initiated ator after ca 55 Ma as a consequence of the conti-nental India–KLA collision (Smith et al. 1994;Beck et al. 1995; Rowley 1996), the eclogitefacies rocks would mark the cessation of theIndia–KLA contact. The lack of Eocene meta-morphic overprint in the blueschists of theShangla area indicates their accretion to theKLA well before the initiation of the India–KLAcollision. On the other hand, timing of the India–KLA collision at ca 61 Ma would show anabsence of marine deposits along the northernmargin of the Indian Plate after the India–KLAcollision. This contradicts the presence ofmarine Eocene fauna (Miscellanea miscella) atthe northern margin of the Indian Plate.

5 The collision of India with the KLA first andthen the India–KLA’s collision with Asia after,should be geologically unrealistic if we considerit on the basis of the DUPAL anomaly and age ofthe Teru Volcanic Formation, without consider-ing the effects of metasomatism and the pres-ence of younger plutons (<41 Ma) within theKLA terrane. Therefore, the collision of theKLA to Asia first and to India later has muchgeological significance and is supported bystructural, stratigraphic, geochemical, andpaleomagnetic evidence.

ACKNOWLEDGEMENTS

We thank Peter J. Treloar, Jonathan C. Aitchison,and Oliver Jagoutz for their critical review onearlier versions of the manuscript. A review byIan Watkinson greatly improved the manuscript.We thank Ian Campbell for critical reading andRobert Hall, Simon Wallis, and Yasufumi Iryu fortheir comments and editorial advice.

REFERENCES

ABRAJEVITCH A. V., ALI J. R., AITCHISON J. C. et al.2005. Neotethys and the India-Asia collision:



Insights from a paleomagnetic study of the Dazhuquophiolite, southern Tibet. Earth and PlanetaryScience Letters 233, 87–102.

ACTON G. D. 1999. Apparent polar wander of India sincethe Cretaceous with implications for regional tecton-ics and true polar wander. In Radhakrishna T. andPiper J. D. A. (eds.) The Indian Subcontinent andGondwana: A Paleomagnetic and Rock MagneticPerspective, pp. 129–75, Memoir Geological Societyof India 44, Geological Society of India, Bangalore.

AHMED M. N., YOSHIDA M. & YOSHIKI F. 2000. Paleo-magnetic study of Utror volcanic formation; remag-netizations and postfolding rotations in Utror area,Kohistan arc, northern Pakistan. Earth, Planets andSpace 52, 425–36.

AHMED M. N., YOSHIKI F. & PAUDEL L. P. 2001. Remag-netization of igneous rocks in Gupis area of Kohistanarc, northern Pakistan. Earth, Planets and Space 53,373–84.

AITCHISON J. C., BADENGZHU D. A. V. I. S. A. et al. 2000.Remnants of a Cretaceous intra-oceanic subductionsystem within the Yarlung-Zangbo Suture (southernTibet). Earth and Planetary Science Letters 183,231–44.

AITCHISON J. C., ALI J. R. & DAVIS A. M. 2007. Whenand where did India and Asia collide? Journal ofGeophysical Research 112, B05423, doi:10.1029/2006JB004706.

ALI J. R. & AITCHISON J. C. 2008. Gondwana to Asia:Plate tectonics, paleogeography and the biologicalconnectivity of the Indian sub-continent from theMiddle Jurassic through latest Eocene (166–35 Ma).Earth Science Reviews 88, 145–66.

ALLEGRE C. J., COURTILLOT V., TAPPONNIER P. et al.1984. Structure and evolution of the Himalaya-Tibetorogenic belt. Nature 307, 17–22.

ALLEMANN F. 1979. Time of emplacement of the ZhobValley ophiolite and Bela ophiolite, Balochistan (pre-liminary report). In Farah A. and Dejong K. A. (eds.)Geodynamics of Pakistan, pp. 213–42, GeologicalSurvey of Pakistan, Quetta.

ANCZKIEWICZ R., BURG J.-P., VILLA I. M. & MEIER M.2000. Late Cretaceous blueschist metamorphism inthe Indus Suture Zone, Shangla region, PakistanHimalaya. Tectonophysics 324, 111–34.

ARBARET L., BURG J.-P., ZEILINGER G., CHAUDHRY N.,HUSSAIN S. & DAWOOD H. 2000. Pre-collisional anas-tomosing shear zones in the Kohistan arc, NW Paki-stan. In Khan M. A., Treloar P. J., Searle M. P. andJan M. Q. (eds.) Tectonics of the Nanga Parbat Syn-taxis and the Western Himalaya, Geological Society,London, Special Publication 170, 295–311.

BARD J. P. 1983. Metamorphism of an obducted islandarc: Example of the Kohistan sequence (Pakistan) inthe Himalayan collided range. Earth and PlanetaryScience Letters 65, 133–44.

BARD J. P., MALUSKI H., MATTE P. & PROUST F. 1980.The Kohistan sequence; crust and mantle of an

obducted island arc. In Tahirkheli R. A. K., Jan M. Q.and Majid M. (eds.) Proceedings of the InternationalCommittee on Geodynamics, Group 6 Meeting, pp.87–93, University of Peshawar, Department ofGeology, Peshawar.

BECK R. A., BURBANK D. W., SERCOMBE W. J. et al.1995. Stratigraphic evidence for an early collisionbetween northwest India and Asia. Nature 373, 55–8.

BENDER F. K. & RAZA H. R. 1995. The geology of Paki-stan. In Bender, F. K. and Raza, H. A. (eds.) Beitragezur regionalen Geologie der Erde 25, p. 414,Schweizerbart Science Publishers, Stuttgart.

BERGGREN W. A., KENT D. V., SWISHER C. C. & AUBRY

M. P. 1995. A revised Cenozoic geochronology andchronostratigraphy. In Berggren W. A., Kent D. V.,Aubry M. P. and Hardenbol J. (eds.) Geochronology,Time Scales and Global Stratigraphic Correlation,pp. 129–212, Society of Economic Paleontologistsand Mineralogists (SEPM) Special Publication 54,SEPM, Tulsa, OK.

BESSE J. & COURTILLOT V. 2002. Apparent and truepolar wander and the geometry of the geomagneticfield in the last 200 Myr. Journal of GeophysicalResearch 107, 2300, doi:10.1029/2000JB000050.

BESSE J., COURTILLOT V., POZZI J. P., WESTPHAL M. &ZHOU Y. X. 1984. Paleomagnetic estimates of crustalshortening in the Himalayan thrusts and Zangbosuture. Nature 311, 621–26.

BIGNOLD S. M. & TRELOAR P. J. 2003. Northward sub-duction of the Indian plate beneath the Kohistanisland arc, Pakistan Himalaya: New evidence fromisotopic data. Journal of the Geological Society ofLondon 160, 377–84.

BOSSART P. & OTTIGER R. 1989. Rocks of the MurreeFormation in Northern Pakistan: Indicators of adescending foreland basin of late Paleocene to middleEocene age. Eclogae Geologicae Helvetia 82, 133–65.

BURG J.-P., BODINIER J., CHAUDHRY M. A., HUSSAIN S.S. & DAWOOD H. 1998. Intra-arc mantle-crust tran-sition and intra-arc mantle diapirs in the Kohistancomplex (Pakistani Himalaya): Petro-structural evi-dence. Terra Nova 10, 74–80.

CHAUVEL C. & BLICHERT-TOFT J. 2001. A hafniumisotope and trace element perspective on melting ofthe depleted mantle. Earth and Planetary ScienceLetters 190, 137–51.

CLIFT P. D., HANNIGAN R., BLUSZTAJN J. & DRAUT A.E. 2002. Geochemical evolution of the Dras–KohistanArc during collision with Eurasia: Evidence fromthe Ladakh Himalaya, India. Island Arc 11, 256–73.

COWARD M. P., WINDLEY B. F., BROUGHTON R. D. et al.1986. Collision Tectonics in the NW Himalayas. InCoward M. P. and Ries A. C. (eds.) Collision Tecton-ics, Geological Society, London, Special Publication19, 203–19.



COWARD M. P., BUTLER R. W. H., KHAN M. A. & KNIPE

R. J. 1987. The tectonic history of Kohistan andits implications for Himalayan structure. Journalof the Geological Society of London 144, 377–91.

DANISHWAR S., STERN R. J. & KHAN M. A. 2001. Fieldrelations and structural constraints on the Teru Vol-canic Formation, northern Kohistan terrane, Paki-stani Himalayas. Journal of Asian Earth Sciences19, 683–95.

DE SIGOYER J., CHAYAGNAC V., BLICHERT-TOFT J. et al.2000. Dating the Indian continental subduction andcollisional thickening in the northwest Himalaya:Multichronology of the Tso Morari eclogites. Geology28, 487–90.

DEBON F., LE FORT P., SHAPPARD S. M. F. & SONNET J.1987. The four belts of Transhimalaya-Himalaya; Achemical, mineralogical, isotopic, and chronologicalsynthesis along a Tibet-Nepal section. Journal ofPetrology 27, 219–50.

DHUIME B., BOSCH D., BODINIER J.-L. et al. 2007. Mul-tistage evolution of the Jijal ultramafic-maficcomplex (Kohistan, N Pakistan): Implications forbuilding the roots of island arcs. Earth and Plan-etary Science Letters 261, 179–200.

DHUIME B., BOSCH D., GARRIDO C. J. et al. 2009.Geochemical architecture of the lower- to middle-crustal section of a paleo-island arc (Kohistancomplex, Jijal–Kamila area, Northern Pakistan):Implications for the evolution of an oceanic subduc-tion zone. Journal of Petrology 50, 531–69.

DING L., KAPP P. & WAN X. Q. 2005. Paleocene–Eocenerecord of ophiolite obduction and initial India–Asia collision, south central Tibet. Tectonics 24,TC3001.

GAETANI M. & GARZANTI E. 1991. Multicyclic history ofthe northern India continental margin (NW Hima-laya). American Association of Petroleum GeologistsBulletin 75, 1427–46.

GAETANI M., JADOUL F. & GARZANTI E. 1993. Jurassicand Cretaceous organic events in the N Karakoram:age constraints from sedimentary rocks. In TreloarP. J. and Searle M. P. (eds.) Himalayan Tectonics,Geological Society, London, Special Publication 74,39–52.

GEORGE M. T., HARRIS N. B. W. & BUTLER R. W. H.1993. The tectonic implications of contrasting post-collisional magmatism between the Kohistan islandarc and the Nanga Parbat-Haramosh massif, Paki-stan Himalaya. In Searle M. P. and Treloar P. J. (eds.)Himalayan Tectonics, Geological Society, London,Special Publication 74, 173–91.

GRECO A., MARTINOTTI G., PAPRITZ K., RAMSAY J. G. &REY R. 1989. The Himalayan crystalline rocks of theKaghan Valley (NE-Pakistan). Eclogae GeologicaeHelvetiae 82, 603–27.

GUILLOT S., GARZANTI E., BARATOUX D., MARQUER D.,MAHÉO G. & DE SIGOYER J. 2003. Reconstructing

the total shortening history of the NW Himalaya.Geochemistry Geophysics Geosysetems 4, 1064, doi:10.1029/2002GC000484.

HAMILTON W. E. 1994. Subduction systems and magma-tism. In Smellif J. L. (ed.) Volcanism Associatedwith Extension at Consuming Plate Margins, Geo-logical Society, London, Special Publication 81, 3–28.

HART S. R. 1984. A large-scale isotope anomaly inthe southern hemisphere mantle. Nature 309, 753–57.

HAYDEN H. H. 1916. Notes on geology of Chitral, Gilgitand Pamir. Records of the Geological Survey of India45, 271–335.

HEUBERGER S., SCHALTEGGER U., BURG J.-P. et al.2007. Age and isotopic constraints on magmatismalong the Karakoram-Kohistan Suture Zone, NWPakistan: Evidence for subduction and continuedconvergence after India-Asia collision. SwissJournal of Geoscience 100, 85–107.

HONEGGER K., DIETRICH V., FRANK W., GANSSER A.,THÖNI M. & TROMMSDORF V. 1982. Magmatism andmetamorphism in the Ladakh Himalaya (the Indus-Tsangpo suture zone). Earth and Planetary ScienceLetters 60, 253–92.

INTERNATIONAL COMMISSION ON STRATIGRAPHY

2009. International Stratigraphic Chart [online][Cited 10 May, 2011.] Available from: http://www.stratigraphy.org/column.php?id=Chart/Time Scale.

JAGOUTZ O. 2010. Construction of the granitoid crust ofan island arc. Part II: A quantitative petrogeneticmodel. Contributions to Mineralogy and Petrology160, 359–81.

JAGOUTZ O., MÜNTENER O., BURG J.-P., ULMER P. &JAGOUTZ E. 2006. Lower continental crust formationthrough focused flow in km-scale melt conduits: Thezoned ultramafic bodies of the Chilas Complex in theKohistan Island arc (NW Pakistan). Earth and Plan-etary Science Letters 242, 320–42.

JAGOUTZ O. E., BURG J.-P., HUSSAIN S. et al. 2009. Con-struction of the granitoid crust of an island arc part I:Geochronological and geochemical constraints fromthe plutonic Kohistan (NW Pakistan). Contributionsto Mineralogy and Petrology 158, 739–55.

JAN M. Q. & HOWIE R. A. 1981. The mineralogy andgeochemistry of the metamorphosed basic and ultra-basic rocks of the Jijal complex, Kohistan, N.W. Paki-stan. Journal of Petrology 22, 85–126.

JAN M. Q., KHAN M. A. & QAZI M. S. 1993. The Sapatmafic-ultramafic complex, Kohistan arc, North Paki-stan. In Treloar P. J. & Searle M. P. (eds.) HimalayanTectonics, Geological Society, London, Special Publi-cation 74, 113–21.

KANEKO Y., KATAYAMA I., YAMAMOTO H. et al. 2003.Timing of Himalayan ultrahigh-pressure metamor-phism: Sinking rate and subduction angle of theIndian continental crust beneath Asia. Journal ofMetamorphic Geology 21, 589–99.



KHAN M. A., JAN M. Q. & WEAVER B. L. 1993. Evolu-tion of the lower arc crust in Kohistan, N. Pakistan:Temporal arc magmatism through early, mature andintra-arc rift stages. In Treloar P. J. and Searle M. P.(eds.) Himalayan Tectonics, Geological Society,London, Special Publication 74, 123–38.

KHAN M. A., STERN R. J., GRIBBLE R. F. & WINDLEY B.F. 1997. Geochemical and isotopic constraints on sub-duction polarity, magma source, and paleogeographyof the Kohistan intra-oceanic arc, northern PakistanHimalaya. Journal of the Geological Society ofLondon 154, 935–46.

KHAN M. A., TRELOAR P. J., KHAN T., QAZI M. S. & JAN

M. Q. 1998. Geology of the Chalt–Babusar transect,Kohistan terrane, N, Pakistan: implications for theconstitution and thickening of island-arc crust.Journal of Asian Earth Sciences 16, 253–68.

KHAN S. D., WALKER D. J., HALL S. A., BURKE K. C.,SHAH M. T. & STOCKLI L. 2009. Did the Kohistan-Ladakh island arc collide first with India? GeologicalSociety of America Bulletin 121, 366–84.

KHAN T. 1994. Evolution of the “Upper and MiddleCrust in Kohistan Island Arc”, North Pakistan.PhD thesis, National Centre of Excellence in Geology,University of Peshawar, Peshawar.

KLOOTWIJK C. T., CONAGHAN P. J. & POWELL C. M.1985. The Himalayan arc: Large-scale continentalsubduction, oroclinal bending, and back-arc spread-ing. Earth and Planetary Science Letters 75, 167–83.

KLOOTWIJK C. T., GEE J. S., PIERCE J. W., SMITH G. M.& MCFADDEN P. L. 1992. An early India-Asia contact:Paleomagnetic constraints from Ninetyeast Ridge,ODP Leg 121. Geology 20, 395–98.

KLOOTWIJK C. T., CONAGHAN P. J., NAZIRULLAH R. &DE JONG K. A. 1994. Further paleomagnetic datafrom Chitral (Eastern Hindukush): Evidence foran early India-Asia contact. Tectonophysics 237,1–25.

MAHÉO G., BERTRAND H., GUILLOT S., VILLA I. M.,KELLER F. & CAPIEZ P. 2004. The South LadakhOphiolites (NW Himalaya, India): An intra-oceanictholeiitic arc origin with implication for the closureof the Neo-Tethys. Chemical Geology 203, 273–303.

MILLER D. J., LOUCKS R. R. & ASHRAF M. 1991.Platinum-group element mineralization in the Jijallayered ultramafic-mafic complex, Pakistani Hima-laya. Economic Geology 86, 1093–102.

MOLNAR P. & TAPPONNIER P. 1975. Cenozoic tectonics ofAsia: Effects of a continental collision. Science 189,419–26.

NAJMAN Y., PRINGLE M., GODIN L. & OLIVER G. 2001.Dating of the oldest continental sediments from theHimalayan foreland basin. Nature 410, 194–97.

NOWELL G. M., KEMPTON P. D., NOBLE S. R. et al. 1998.High precision Hf isotope measurements of MORBand OIB by thermal ionisation mass spectrometry;

insights into the depleted mantle. Chemical Geology149, 211–23.

O’BRIEN P. J., ZOTOY N., LAW R., KHAN M. A. & JAN M.Q. 2001. Coesite in Himalayan eclogite and implica-tions for models of India-Asia collision. Geology 29,435–38.

PATCHETT P. J. & TATSUMOTO M. 1980. Hafnium isotopevariations in oceanic basalts. Geophysical ResearchLetters 7, 1077–80.

PATRIAT P. & ACHACHE J. 1984. India–Eurasia collisionchronology has implications for crustal shorteningand driving mechanism of plates. Nature 311, 615–21.

PATZELT A., LI H., WANG J. & APPEL E. 1996. Paleo-magnetism of Cretaceous to Tertiary sedimentsfrom southern Tibet: Evidence for the extent of thenorthern margin of India prior to the collision withEurasia. Tectonophysics 259, 259–84.

PETTERSON M. G. & TRELOAR P. J. 2004. Volcanostratig-raphy of arc volcanic sequences in the Kohistan arc,North Pakistan: Volcanism within island arc, back-arc-basin, and intra-continental tectonic settings.Journal of Volcanology and Geothermal Research130, 147–78.

PETTERSON M. G. & WINDLEY B. F. 1985. Rb-Sr datingof the Kohistan arc batholith in the Trans-Himalayaof N. Pakistan and tectonic implications. Earth andPlanetary Science Letters 74, 45–75.

PETTERSON M. G. & WINDLEY B. F. 1991. Changingsource region of magma and crustal growth in theTrans-Himalayas: Evidence from Chalt volcanics andKohistan batholith, Kohistan, northern Pakistan.Earth and Planetary Science Letters 102, 326–41.

PETTERSON M. G., WINDLEY B. F. & LUFF I. W. 1991.The Chalt volcanics, Kohistan, N Pakistan: high-Mgtholeiitic and low-Mg calc-alkaline volcanism in aCretaceous island arc. In Sharma K. K. (ed.) Geologyand Geodynamic Evolution of the Himalayan Colli-sion Zone, Part 1, pp. 19–30, Physics and Chemistryof the Earth, Pergamon, Oxford.

PUDSEY C. J. 1986. The Northern Suture, Pakistan:Margin of a Cretaceous island arc. Geological Maga-zine 123, 405–23.

PUDSEY C. J., COWARD M. P., LUFF I. W., SHACKLETON

R. M., WINDLEY B. F. & JAN M. Q. 1985. The collisionzone between the Kohistan arc and the Asian plate inNW Pakistan. Transactions of the Royal Society ofEdinburg, Earth Sciences 76, 464–79.

REHMAN H. U., YAMAMOTO H., KANEKO Y., KAUSAR A.B., MURATA M. & OZAWA H. 2007. Thermobaricstructure of the Himalayan Metamorphic Belt inKaghan Valley, Pakistan. Journal of Asian EarthSciences 29, 390–406.

REPLUMAZ A. & TAPPONNIER P. 2003. Reconstruction ofthe deformed collision zone between India and Asiaby backward motion of lithospheric blocks. Journalof Geophysical Research 108 (B6), 2285, doi: 10.1029/2001JB000661.



REPLUMAZ A., NEGREDO A. M., GUILLOT S. & VILLASE-NOR A. 2010. Multiple episodes of continental subduc-tion during India/Asia convergence: Insight fromseismic tomography and tectonic reconstruction.Tectonophysics 483, 125–34.

ROBERTSON A. H. F. & COLLINS A. S. 2002. ShyokSuture Zone, N. Pakistan: Late Mesozoic-Tertiaryevolution of a critical suture separating the oceanicLadakh Arc from the Asian continental margin.Journal of Asian Earth Sciences 20, 309–51.

ROLLAND Y., PICARD C., PÊCHER A., LAPIERRE H.,BOSCH D. & KELLER F. 2002. The Ladakh arc of NWHimalaya: Slab melting and mantle interactionduring fast northward drift of Indian Plate. Chemi-cal Geology 182, 139–78.

ROWLEY D. B. 1996. Age of collision between India andAsia: A review of the stratigraphic data. Earth andPlanetary Science Letters 145, 1–13.

SCHALTEGGER U., ZEILINGER G., FRANK M. & BURG

J.-P. 2002. Multiple mantle sources during island arcmagmatism: U–Pb and Hf isotopic evidence from theKohistan arc complex, Pakistan. Terra Nova 14, 461–68.

SCHALTEGGER U., HEUBERGER H., FRANK M., FON-TIGNIE M., SERGEEY S. & BURG J.-P. 2004. Tracingcrust-mantle interaction during Karakoram-Kohistan accretion (NW Pakistan). Geochimica etCosmochimica Acta 68 (11), Supplement 1, A640.

SCHÄRER U., HAMET J. & ALLEGRE C. J. 1984. TheTranshimalaya (Gangdese) plutonism in the Ladakhregion: A U–Pb and Rb-Sr study. Earth and Plan-etary Science Letters 67, 327–39.

SCHETTINO A. & SCOTESE C. R. 2005. Apparent polarwander paths for the major continents (200 Ma to thepresent day): A palaeomagnetic reference frame forglobal plate tectonic reconstructions. GeophysicalJournal International 163, 727–59.

SEARLE M. P. 1991. Geology and Tectonics of the Kara-koram Mountains. John Wiley, Chichester.

SEARLE M. P. WINDLEY B. F., COWARD M. P. et al. 1987.The closing of Tethys and the tectonics of the Hima-laya. Geological Society of America Bulletin 98, 678–701.

SEARLE M. P., KHAN M. A., FRASER J. E., GOUGH S. J.& JAN M. Q. 1999. The tectonic evolution of theKohistan collision belt along the KarakoramHighway transect, north Pakistan. Tectonics 18, 929–49.

SHARMA K. K. & GUPTA K. R. 1983. Calc-alkaline islandarc volcanism in Indus-Tsangpo suture zone. InThakur V. C. and Sharma K. K. (eds.) Geology ofIndus Suture Zone of Ladakh, pp. 71–8, WadiaInstitute of Himalayan Geology, Dehra Dun.

SMITH H. A., CHAMBERLAIN C. P. & ZEITLER P. K.1994. Timing and duration of Himalayan meta-morphism within the Indian Plate, NorthwestHimalaya, Pakistan. Journal of Geology 102, 493–508.

SPENCER D. A., TONARINI S. & POGNANTE U. 1995.Geochemical and Sr-Nd isotopic characterisation ofHigher Himalayan eclogites (and associated meta-basites). European Journal of Mineralogy 7, 89–102.

SULLIVAN M. A., WINDLEY B. F., SAUNDERS A. D.,HAYNES J. R. & REX D. C. 1993. A palaeogeographicreconstruction of the Dir Group: evidence for mag-matic arc migration within Kohistan, N. Pakistan. InTreloar P. J. & Searle M. P. (eds.) Himalayan Tecton-ics, Geological Society, London, Special Publication74, 139–60.

TAHIRKHELI R. A. K. 1979. Geology of Kohistan andadjoining area Eurasian and Indo-Pakistan conti-nents, Pakistan. Geological Bulletin University ofPeshawar Special Issue 15, 1–51.

TAHIRKHELI R. A. K., MATTAUER M., PROUST F. &TAPPONNIER P. 1979. The India-Eurasia suture zonein northern Pakistan: Synthesis and interpretation ofrecent data at plate scale. In Farah A. and De JongK. A. (eds.) Geodynamics of Pakistan Quetta, pp.125–30, Geological Survey of Pakistan, Quetta.

TAN X., GILDER S., KODAMA K. P. et al. 2010. New paleo-magnetic results from the Lhasa block: Revised esti-mation of latitudinal shortening across Tibet andimplications for dating the India-Asia collision. Earthand Planetary Science Letters 293, 396–404.

TONARINI S., VILLA I. M., OBERLI F. et al. 1993. Eoceneage of eclogite metamorphism in Pakistan Himalaya:Implications for India-Eurasia collision. Terra Nova5, 13–20.

TRELOAR P. J., REX D. C., GUISE P. G. et al. 1989. K/Arand Ar/Ar geochronology of the Himalayan collisionin NW Pakistan: Constraints on the timing of sutur-ing, deformation, metamorphism and uplift. Tecton-ics 4, 881–909.

TRELOAR P. J., BROADIE K. H., COWARD M. P. et al.1990. The evolution of the Kamila shear zone,Kohistan, Pakistan. In Salisbury M. H. and FountainD. M. (eds.) Exposed Cross Sections of the Continen-tal Crust, pp. 175–214, Kluwer Academic Press,Amsterdam.

TRELOAR P. J., PETTERSON M. G., JAN M. Q. & SULLI-VAN M. A. 1996. A re-evaluation of the stratigraphyand evolution of the Kohistan arc sequence, PakistanHimalaya: Implications for magmatic and tectonicarc-building processes. Journal of the GeologicalSociety of London 153, 681–93.

VAN DER VOO R., SPACKMAN W. & BIJWAARD H. 1999.Tethyan subducted slabs under India. Earth andPlanetary Science Letters 171, 7–20.

VERVOORT J. D., PATCHETT P. J., GEHRELS G. E. &NUTMAN A. P. 1996. Constraints on early Earth dif-ferentiation from hafnium and neodymium isotopes.Nature 379, 624–27.

VERVOORT J. D., PATCHETT P. J., BLICHERT-TOFT J. &ALBARÊDE F. 1999. Relationships between Lu-Hfand Sm-Nd isotopic systems in the global



sedimentary system. Earth and Planetary ScienceLetters 168, 79–99.

VILLA I. M. 1998. Isotope closure. Terra Nova 10, 42–7.YAMAMOTO H. & NAKAMURA E. 2000. Timing of mag-

matic and metamorphic events in the Jijal complex ofthe Kohistan arc deduced from Sm-Nd dating of maficgranulites. In Khan M. A., Treloar P. J., Searle M. P.and Jan M. Q. (eds.) Tectonics of the Nanga ParbatSyntaxis and the Western Himalaya, GeologicalSociety, London, Special Publication 170, 313–19.

YAMAMOTO H., REHMAN H. U., KANEKO Y. & KAUSAR

A. B. 2011. Tectonic stacking of back-arc formationsin the Thelichi section (Indus valley) of the Kohistanarc, northern Pakistan. Journal of Asian Earth Sci-ences 40, 417–26.

YIN A. 2006. Cenozoic tectonic evolution of the Hima-layan orogen as constrained by along-strike variationof structural geometry, exhumation history, and fore-land sedimentation. Earth Science Reviews 76, 1–131.

YIN A. & HARRISON T. M. 2000. Geologic evolution ofthe Himalayan-Tibetan orogeny. Annual Review ofEarth and Planetary Sciences 28, 211–80.

ZAMAN H. & TORII M. 1999. Paleomagnetic study ofCretaceous red beds from the eastern Hindukushranges, northern Pakistan; paleoarc construction ofthe Kohistan-Karakoram composite unit before theIndia-Asia collision. Geophysical Journal Interna-tional 136, 719–38.

ZANCHI A., POLI S., FUMAGALLI P. & GAETANI M. 2000.Mantle exhumation along the Tirich Mir Fault Zone,NW Pakistan: Pre-mid-Cretaceous accretion of theKarakoram terrane to the Asian margin. In KhanM. A., Treloar P. J., Searle M. P. and Jan M. Q. (eds.)Tectonics of the Nanga Parbat Syntaxis and theWestern Himalaya, Geological Society, London,Special Publication 170, 237–52.

ZEITLER P. K., TAHIRKHELI R. A. K., NAESSER C.,JHONSON N. & LYONS J. 1981. Preliminary fissiontrack ages from the Swat Valley, Northern Pakistan.Geological Bulletin, University of Peshawar SpecialIssue 13, 63–5.

ZINDLER A. & HART S. R. 1986. Chemical geodynamics.Annual Review of Earth and Planetary Sciences 14,493–571.



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