Stephen Crittenden

A Preliminary biostratigraphical study

(Sedimentology scheme from work by Dr Saif Khan Tanoli)

2011

Acknowledgement From 2010 until 2012 I worked as a stratigrapher in Kuwait (KOC)

under the leadership of Abdulaziz Al-Fares and Ghaida Al-Sahlan. Ghaida suggested I look at the stratigraphy of the EnjefaBeach section in order to throw some light on the age dating of the sediments that were being studied by Saifullah Khan Tanoli(also with KOC). I departed Kuwait with the project unfinished.

These slides are the result of my unfinished preliminary study (2011) and I owe a huge debt of gratitude to Saif for his providing the initial results of his sedimentological studies of the Enjefabeach section for my use as a framework.

http://www.searchanddiscovery.com/documents/2012/50602tanoli/ndx_tanoli.pdf

Sedimentological evidence for the Late Holocene sea level change in the Enjefa beach exposures of Kuwait NW Arabian Gulf. 2014 online and 2015. S.K . Tanoli-. Arab Journ of Geosciences, 8: 6064 - 6074

Introduction

The desert surface of Kuwait is carved down into a series of clastic deposits called the Kuwait Group that ranges in age from Miocene to Recent.

Objective: to investigate the biostratigraphy, age and the relationship of the sedimentary layers to sea-level fluctuations, of the exposed Modern and presumed Holocene (and perhaps Pleistocene) sedimentary deposits at Enjefa Beach, Salwa in Kuwait.

Summary Conclusions The represented sedimentary environments - very

shallow marine, moderate to high energy, sand clasticsediments of the beach exposures yield no microfossils (foraminifera, ostracods and calcareous nannoplankton) suitable for age determination.

Age relationships are only determined from stratigraphical layering position of the strata.

At present it has not been possible to determine if Pleistocene (or older) sediments are present.

The shelly macrofauna (bivalves and gastropods) may be suitable for radiocarbon dating and for carbon and strontium isotope analysis.

The following discussion is preliminary and based on only a “quick-look” by me of Enjefa beach.

Way Forward and Recommendations Mapping of facies distribution

Cliff Section and beach profile logging

Stratigraphical correlation of profiles and facies

Development of a 3d visual model of the faciesdistribution and stratigraphical layering

Age dating of units

Biostratigraphy / biofacies

Radioactive dating

Strontium isotope

Carbon isotope

Comprehensive literature search

Strontium Isotope dating This method provides a numerical age related to a global scale based on the 87Sr/86Sr ratio

of past seawaters. The amount of radiogenic strontium in the world’s oceans is principally controlled by contributions from continental runoff, exhalations at oceanic ridges and meteoric waters. In terms of geological time oceanic mixing is instantaneous. The assumption that the 87Sr/86Sr ratio of the world’s oceans has fluctuated uniformly through time has enabled a Global Standard Strontium Curve (GSSC) to be established (Howarth and McArthur, 1997). Since Sr is taken up by aquatic organisms in equilibrium with the surrounding water it is possible to use their fossilised remains as a proxy for oceanic seawater. Suitable material includes molluscs, foraminifera, conodonts, fish teeth and calcareous algae. whole rock samples (carbonates, dolomitised carbonates and evaporites) for analysis providing any diagenesis was early.

Non-oceanic environments will of course give rise to atypical Sr ratios which will differ from the global seawater strontium standard. Closeness to a major river system is one such environment where one would expect Sr ratios to vary from the coeval oceanic values. Data from individual samples are compared to the Howarth and McArthur database. This database includes all published and many unpublished Sr ratios which have first been subjected to a vetting procedure and weighted for stratigraphical, biostratigraphical and chemical accuracy. The figure below illustrates the Pliocene -Pleistocene global seawater Sr curve. In reality the comparison is made with the Global Strandard Strontium Curve using a “look up” table.

The standard cost of £260 covers sample preparation and sample analysis. Reporting time is based on requirement. The cost can be reduced for a large projects (50+ samples). Turnaround time is normally 3-4 weeks from receipt of samples.

Radiocarbon dating, 14 C Suitable for dating sediments up to c.40Ka old as long

as they contain suitable biogenic material (molluscs, microfossils, wood). Non-marine as well as marine and terrestrial sediments can be dated using this method. Each sample is prepared in the same way as for a micropalaeontological analysis. Suitable specimens are selected by picking through the residue.

Cost by quotation – expensive!

Database Field Trip with Dr Saifullah Tanoli to Enjefa Beach

(N0vember 3rd, 2011) for outcrop observation.

A “follow-up” Initial Field investigation and outcrop observation and sampling by Dr Stephen Crittenden, of Enjefa Beach (November 11th, 2011).

Sample analysis for calcareous nannoplankton by Dr Adi Kadar

Sample analysis for microfauna (foraminifera and ostracodsetc) – still in progress.

No literature survey has been performed for relevant articles in the scientific literature.

Post Field trip discussion / debate – Dr Abdul Kader, Dr Irene Truskowski, Dr Adi Kadar and Dr Stephen Crittenden.

The Surface Geology of Kuwait.A long history of outcrop mapping and study mainly associated with the search for oil. All studies report that age dating of the surface outcrops in Kuwait is hindered by lack of or scarcity of suitable fossils.

March, 1913. First Geological Survey of Kuwait by APOC. Report issued in May 1913. E. H. Pascoe (and S. Lister James). Additional survey in 1917.

Eastern General Syndicate geological survey, Sept 1924. Dr Arnold Heim.

Frank Holmes. 1926 – 1927, water well drilling but no water found (only traces of oil in one well).

APOC Geological Survey January 7th to February 7th , 1926. A. G. H Mayhew and B. K. N. Wylie.

APOC Geological Survey mid-December 1931 to mid-January 1932. A. H. Taitt & P. T. Cox.

APOC Geological Survey & drilling. 14th February – 13th April, 1932. P. T. Cox & G. M. Shaw. Kuwait-1 at Bahrah and Kuwait-2 at Burgan.

KOC Geological Survey, Summer 1935. Ralph Rhoades, G. H. Crowell and P. T. Cox.

Geological map by Vienna Geological Survey, 1968.

Geological map by Hunting Surveys for KOC, 1980 & 1981

Many, many studies by researchers at Kuwait University, KOC and at KISR particularly on Holocene to Recent sediments, eg. Recent surface deposit map, 1980.

StratigraphyQuaternary Period comprises the Holocene and Pleistocene epochs.

Holocene from Present Day to 11,700 yrs BP. – a period of sea-level rise.

Pleistocene from 11,700 yrs to 2.58 m yrs BP – a period of repeated glaciations. The last glacial maximum period was 21,000 – 18,000yrs BP = sea-level low / regression during which the Arabian Gulf was land (sea-floor exposed) – an extensive low lying coastal plain reworked by the subsequent Holocene transgression.

Holocene and Pleistocene floras and faunas are essentially modern. There are no faunal biozones for the Holocene.

The surface sediments of Kuwait

Comprise Quaternary (Modern & Holocene deposits plus Pleistocene gravels and sands of the Upper Dibdibba Formation)

Modern to Holocene sediments include: Aeolian sands Playa deposits Coastal sabkha deposits – eg northern shore of kuwait Bay Beach deposits – eg Enjefa Beach

Sediments are the result of a number of depositional environments and processes such as desert plain, aeolian dunes, slope and alluvial fans and beach.

Sediments are either unconsolidated or cemented by calcium carbonate and silica precipitation. Lithification of the sediments is variable.

Outcrop of older rocks do occur as for example: Jal Az-Zorescarpment (Mio-Pliocene) in north Kuwait and at AhmadiQuarry (Eocene).

North Side of Kuwait Bay:Jal Az-Zor Escarpment Clastic coastal

sabkha

Supratidal flat sabkha covered by mobile sand sheet,small dunes anchored by vegetation

Jal Az-Zor escarpment

Thin Dibdibba Formation unconformably upon Fars Formation

SC 2010

Ahmadi QuarryGeneral view of AhmadiQuarry showing Kuwait Group (Recent and Holocene & perhaps Mio-Pleistocene)sediments unconformablyoverlying the Eocene Dammam Formation.

Approx line of unconformable contact (palaeokarst surface)

SC 2010

Enjefa Beach General Observations Coastal cliff of low elevation < 3metres, at back of the beach, and

beach ledges.

Presumed Holocene to Modern sediments.

Pebbly, calcareous, highly oxidised sandstones.

Calcium carbonate cemented.

Variously laminated, graded and cross-bedded and with layers of fossiliferous (skeletal debris mainly marine molluscs) sediment.

Changes in lithology and sedimentology are a reflection of climate change, sediment supply and sea-level fluctuations.

Wave-cut platform / terrace and beach benches (including coquina levels) both ancient and modern and Beach Rock.

A diverse facies mosaic as a result of a complex record of deposition (S K Tanoli).

Enjefa Beach at Low tideSalmiya

Intertidal wave cut platform / terrace –?Beach Rock

Mean HWT level

Beach cliff cut into Holocene sediments

Edge of cliff

South

North

General lithofacies observations of the “Holocene” sediments (Dr Saif Tanoli).

From south to north along the beach (Dr Saif Tanoli)

Horizontally laminated (HLB)

Trough cross-bedded (TCB)

Planar wedge shaped and ripple cross-bedded (PWRCB)

Bioturbated facies (BF)

Enjefa Beach.

Plastic bag within sediments

In-situ deposits (HLB)

Beach cliff top surface disturbed and cut into / trenched by modern day man activity: Plastic bag horizon is a useful stratigraphic marker!!.

The whole beach area and promenade show evidence of modern mans’ activity: trenching and rubble fill, sea wall development and rubbish / litter.

(I)

Downcutting surface of Modern human activity

Study needed to determine exact position of boundary

Photo by Rinaldi Mulyono

Enjefa Beach – horizontally laminated beds (HLB) lithofacies.

Entire section subject to human activity. Sea-wall defence collapse.

In this section the only interval not disturbed is the HLB.

The white cloth sample bags denote samples 1 & 2 taken for analysis.

1

2

(II)

HLB Samples 1 &2

1

2

Shell / coquina bed, storm layers

Series of fining up horizontally laminated beds. Overall coarsening-up trend of the beds.

Marine bivalves

Enjefa Beach

Shelly layers within cliff section of the HLB facies.Bivalves and Conus type gastropods. Candidates for geochemical dating techniques.

Photographs by Rinaldi Mulyono

Enjefa Beach – trough cross-bedded sediments (TCB)

Sample 3

Trough cross bedded very calcareous sandstone.

Tidal channel or inlet environment. High energy regime.

Modern “pot” erosion caused by wave agitated blocks of sediment and modern brick

(III)

Shelly fossils very rare.

Enjefa beach – Planar wedge shaped and ripple cross-bedded lithofacies (PWRCB)

Tidal deposits comprising cross-bedded calcareous sandstones – herring bone pattern in part suggesting a tidal environment – ebb and flow currents.

Bioturbated facies(?Skolithos)

Very rare fossil / shells

(IV)

GEOL 553 Lecture 3; Sedimentary Sequences

Sandy

Shores?

University of Alberta

“Ichnology Research

Group

Enjefa Beach-Bioturbated Facies(BF)

Bioturbated faciesinterval calcareous sandstone grading to sandy limestone

Vertical burrows are prominent suggesting suspension feeder dominance. Body fossils (whole bivalve shells) occur – low to moderate energy environment such as a lagoon.

(V)Modern Human activity disturbed layer

Intensely bioturbated interval

Enjefa Beach – Bioturbated Facies

?Skolithus ichnofacies: simple vertical burrows and escape burrows of various types of suspension feeders.

Sub-tidal and intertidal situation of high energy sandy marine environment

Enjefa Beach – photomosaic looking southwest

from intertidal slab surface view point (low tide) X.

(I), (II), (III)

Intertidal slab is a pronounced promontory nose revealed at low tide. A promontory due to differential erosion – hard and soft sediments. Active break up of slab by wave action. Exposed Beach Rock.

Recommended tasks: Log cliff sections / profiles. Map the lateral changes in facies. Establish stratigraphical relation ship between cliff sections and promontory section.

Beach Outcrop Slab of well consolidated sands -?silicified or calcite cement

Enjefa Beach - looking northwards from intertidal slab

surface view point (early morning low tide).

(IV) PWRCB and (V) Bioturbated

facies in cliff at back of beach?Tidal channel sands

Consolidated slab=? Beach Rock

What is the stratigraphicalrelationship of the consolidated slab, the Beach Rock exposure of ?tidal channel sands and the cliff exposure?

Grey, fine to medium grain

Brown / Grey, fine to medium grain with coarse grains and pebbles.

Enjefa Beach – Slab outcropTask: Determine the stratigraphical relationship between the softer less consolidated cliff sediments and the firmer more consolidated beach slab outcrop.

Contact obscured by Modern beach sands and by Modern Human activity

Enjefa Beach – Slab outcrop

Coarse qtz pebbles, shell debris

Joints

Cross stratification (investigate nature -? Hummocky)

Enjefa Beach – relationship between cliff

sections and the consolidated slabs on the beachTask: What is the exact relationship? Conformity? Is this a possible Holocene / Pleistocene boundary surface?

Beach rock?

Enjefa Beach – contact of cliff sediments with beach slab outcrop

Boundary

What is the nature of this boundary?

Enjefa Beach: Present day Intertidal areaView looking North at maximum low tide. Exposed wave cut platform of eroded surface of consolidated ‘Holocene’ ?Pleistocene sediments – an exhumed “surface “– rippled in part. This intertidal area is broken up into slabs and ledges with modern-day sediments (slab rubble, sands and muds) in the intervening gulleys and channels.Slab surface dips gently to the east.Consolidated slab comprises fine to coarse, well cemented sandstones. Are they coincident with coarser channel facies seen in the cliff and beach exposure?

Modern beach sands

Consolidated slab (lithified intertidal terrace / platform) underlain by softer cross bedded sands = ?Beach Rock exposed by erosion

Maximum low tide.

View point

Enjefa Beach-intertidal slab surfaceExhumed and broken-up and eroded ancient (Holocene ?Pleistocene), rippled in part, surface. Terrace / Slab comprises consolidated / lithifiedcalcareous sand and carbonate muds with exhumed coral fragments and shell debris. Slab surface is colonised by modern-day calcareous algae / microbial mat – green, oysters, other bivalves (some burrowing teredotypes), barnacles and limpets and cerithidgastropods grazing the algae.

What is the stratigraphical relationship of this?Beach Rock to beach / cliff section?

Enjefa Beach – wave cut platform

The only indication of “age” is given by stratigraphic position within the whole observed interval.

Intertidal slab of Beach Rock dissected by small channels. Fracture / joint control of erosion.

Upper Bed of consolidated calcareous coarser (?) sandstone and carbonate muds.

Lower bed of softer, less consolidated cross-bedded sandstone.

Enjefa Beach – Recent. Beach Rock

Green-coloured filamentous algal mat.Limpets and barnacles are common. Infaunal burrowers – bivalves.

Abundant Cerethid type gastropods grazing on the algae

Oyster type bivalve

Erosion channel along lines of weakness in the ‘slab’ – joints and fractures.

Mahboulah “Beach Rock”

Modern “Beach Rock” exposed at low tide

Beach Rock https://en.wikipedia.org/wiki/Beachrock