B GIO DC V O TO TRNG I HC M- A CHT

Phan ng Pha

A TNG V LCH S PHT TRIN CC THNH TO KAINOZOI I T GY SNG BA V PH CN

Chuyn ngnh: C sinh v a tng

M s: 62.44.55.10

TM TT LUN N TIN S A CHT

H Ni 2011

Cng trnh c hon thnh ti: B mn a cht, Khoa a cht, Trng i hc M- a cht.

Ngi hng dn khoa hc: 1. GS.TSKH ng Vn Bt Khoa a cht, Trng i hc M- a cht 2. TS. Nguyn Xun Huyn Vin a cht, Vin Khoa hc v Cng ngh Vit Nam

Phn bin 1: PGS.TS Phm Huy Tin

Vin a cht, Vin Khoa hc v Cng ngh Vit Nam

Phn bin 2: PGS.TS ng Vn Bo

Trng i hc Khoa hc T nhin, i hc Quc gia H Ni

Phn bin 3: TS. inh Vn Thun

Vin a cht, Vin Khoa hc v Cng ngh Vit Nam

Lun n s c bo v trc Hi ng chm lun n cp Trng hp ti: Trng i hc M- a cht vo hi: gi ngy. thng. nm 20..

C th tm lun n ti: Th vin Quc gia, H Ni hoc Th vin Trng i hc M- a cht

M U 1- Tnh cp thit ca lun n i t gy (G) Sng Ba c v tr c bit trong cu trc a cht khu vc

Nam Trung b. y l mt G ln dng a ho ni lc c cu trc phc tp, ng thi n cha nhiu thng tin gi tr v lch s pht trin a cht khu vc. Tuy nhin, cho n nay vic nghin cu mi ch dng li mc o v bn a cht cc t l khc nhau v tin hnh mt s cng trnh nghin cu khi qut v cu trc tn kin to, c sinh- a tng Kainozoi (KZ), tim nng khong sn,... khi nghin cu lnh th Nam Vit Nam hoc Nam Trung b. Bn cnh nhng gi tr khoa hc v thc tin t c, cc cng trnh ni trn cn mt s ni dung tn ti cha c gii quyt trit , trong ni ln r nht l s phn chia khc bit gia cc tc gi khc nhau v a tng KZ nh: S lng cc phn v a tng, khi lng v tui thnh to a cht ca mt s phn v c th, cha c nhng nghin cu chi tit v thnh phn vt cht, Chnh cc tn ti ny ang gy ra nhng kh khn nht nh trong vic xc lp mt thang a tng KZ thng nht trn ton G Sng Ba, vic lm sng t lch s hnh thnh pht trin cc thnh to KZ G ny v mt s vn thc t lin quan, c bit l tim nng khong sn.

Xut pht t nhng vn nu trn, NCS la chn ti a tng v lch s pht trin cc thnh to Kainozoi i t gy Sng Ba v ph cn lm lun n Tin s a cht.

2- Mc tiu ca lun n: Mc tiu ca lun n l lm sng t c im a tng v xc lp lch s pht trin cc thnh to KZ G Sng Ba v ph cn phc v cho cng tc iu tra, nh gi, tm kim khong sn v quy hoch khai thc hp l lnh th.

3- Ni dung nghin cu ca lun n: Ni dung nghin cu lun n gii quyt 3 vn chnh: (1) Phn chia, lin kt a tng v xc lp thang a tng KZ thng nht trn ton G Sng Ba; (2) Nghin cu lm sng t lch s pht trin cc thnh to KZ G Sng Ba; (3) Nghin cu, xc lp mi lin quan ca khong sn vi cc thnh to KZ G Sng Ba.

4- i tng v phm vi nghin cu ca lun n: i tng nghin cu ca ti l cc thnh to trm tch, trm tch- phun tro KZ khu vc G Sng Ba. Phm vi nghin cu l G Sng Ba phn b trn a bn cc tnh Kon Tum, Gia Lai v Ph Yn.

5- Cc im mi ca lun n 5.1- Phn chia chi tit v xy dng mt thang a tng thng nht cc thnh

to KZ G Sng Ba; trong , xc lp c mt phn v a tng mi l h tng Bun Tu (N2 bt) c tui Pliocen.

5.2- phn chia lch s pht trin cc thnh to KZ G Sng Ba lm cc giai on: Paleocen- Eocen, Oligocen- Miocen v Pliocen- t.

5.3- xc lp mi lin quan ca khong sn vi v tr a tng, tng trm

tch, c im a hnh- a mo ca cc thnh to KZ G Sng Ba. 6- Cc lun im bo v 6.1- Lun im 1: Cc thnh to KZ G Sng Ba gm 23 phn v a tng

c tui t Miocen gia n hin i. Trong , h tng Bun Tu c tui Pliocen (N2 bt) phn b cc trng Ayun Pa v Krng Pa vi s c mt ca vt liu ni la, to Diatomeae l h tng mi c xc lp.

6.2- Lun im 2: Lch s pht trin cc thnh to a cht ca G Sng Ba trong KZ gm 3 giai on: (1) Paleocen- Eocen: Hot ng bc mn mnh m v magma xm nhp tch cc; (2) Oligocen- Miocen: Chuyn tip t bc mn xm thc sang tch t trm tch lc a cha than cc trng Ayun Pa v Krng Pa; (3) Pliocen- t: Hnh thnh cc bn tch t trm tch lc a- phun tro Pleiku v Kon Tum v m rng cc trng Ayun Pa, Krng Pa trong iu kin hot ng phun tro bazan mnh m. Trng Tuy Ha hnh thnh vo Pleistocen sm v c lp y bi cc thnh to trm tch ngun gc lc a- bin.

7- ngha khoa hc v thc tin ca lun n ngha khoa hc: (1) Kt qu ca lun n lm sng t c im thnh phn

vt cht, c im a tng v lch s pht trin cc thnh to KZ G Sng Ba; gp phn lun gii lch s hnh thnh v pht trin G Sng Ba ni ring v khu vc Nam Trung b ni chung; (2) Hng nghin cu v phng php tip cn ca lun n cn l c s cho vic trin khai nghin cu cc bn trng KZ hnh thnh dc cc i t gy khc nc ta.

ngha thc tin: (1) Kt qu nghin cu phc v trc tip cho cng tc iu tra, nh gi v tm kim khong sn lin quan n cc thnh to KZ; (2) Kt qu nghin cu l ngun ti liu ng tin cy cho cng tc nghin cu a cht, a cht thu vn- a cht cng trnh, a cht mi trng. Kt qu ca lun n cn l c s khoa hc cho cng tc quy hoch v khai thc hp l lnh th theo hng pht trin bn vng.

8- C s ti liu ca lun n: Lun n c xy dng trn c s cc kt qu do NCS trc tip kho st, o v ngoi thc a; phn tch, x l trong phng t nm 1988 n nay; bao gm: (1) Cc ti liu o v kho st ca NCS trc tip thc hin; (2) Cc kt qu nghin cu do NCS ch tr thc hin hoc tham gia cng b (9 bi bo, 3 bi Hi ngh khoa hc, 7 ti cc cp v lun vn thc s a cht ca chnh NCS); (3) Cc kt qu phn tch v thit l khoan lu tr thu thp c; (4) Tham kho cc bo co lu tr khc lin quan.

9- Cu trc ca lun n: Ngoi phn M u v Kt lun, lun n gm 5 chng, c trnh by trong 137 trang nh my, gm 22 hnh, 7 bng, 44 nh minh ha.

10- Li cm n: Lun n c thc hin v hon thnh ti B mn a cht, Khoa a cht, Trng i hc M- a cht, di s hng dn tn tnh, c hiu qu ca GS.TSKH ng Vn Bt v TS. Nguyn Xun Huyn. Trong thi gian thc hin lun n, NCS nhn c s quan tm, to iu kin, gp v gip nhit

tnh ca Ban Lnh o v cc nh a cht thuc nhiu n v khc nhau. Nhn dp ny, NCS xin by t lng bit n chn thnh v s gip qu bu ca cc c nhn v tp th nu trn.

NI DUNG LUN N Chng 1- TNG QUAN V I T GY SNG BA

1.1- iu kin t nhin 1.1.1- c im a l t nhin 1.1.1.1- V tr a l: i t gy Sng Ba nm trong phm vi cc tnh Kon

Tum, Gia Lai v Ph Yn, vi din tch khong 10.500km2. i t gy ko di 280km theo phng Ty Bc- ng Nam (TB-N), t k T xung Tuy Ho.

1.1.1.2- c im a hnh: Gm 4 dng a hnh: Ni, cao nguyn, ng bng ven bin v thung lng. a hnh bin i phc tp, b chia ct mnh v lin tc thay i, c xu hng thp dn v pha nam v nghing dn v pha ng.

1.1.1.3- c im thu vn: Mng thu vn ca vng nghin cu thuc lu vc sng Ba pha nam v sng S San pha bc G.

1.1.1.4- c im kh hu: Vng nghin cu c kh hu nhit i gi ma vi 2 ma ma v ma kh r rt.

1.1.1.5- c im lp ph thc vt: Nhn chung, din tch rng t nhin vn chim t l cao, nhng cht lng rng thp, nhiu ni rng b khai thc kit qu.

1.1.2- c im a cht 1.1.2.1- a tng: a tng trc Kainozoi gm phin kt tinh Tin

Cambri, cc thnh to lc nguyn bin cht, trm tch lc nguyn v trm tch phun tro t axit n trung tnh c tui t Cambri n Kreta. a tng Kainozoi bao gm cc thnh to trm tch lc a cha than HT Sng Ba (N13 sb), trm tch- phun tro xen sinh ha HT Kon Tum (N2 kt); phun tro bazan HT Tc Trng (N2-Q11 tt); cc thnh to trm tch t b ri c nhiu ngun gc v thnh phn khc nhau, phn b khu vc ng bng Tuy Ho v dc cc thung lng sng, sui ln. Ngoi ra, cn c cc thnh to bazan thuc HT Xun Lc (Q12 xl).

1.1.2.2- Magma xm nhp: Trn vng nghin cu, cc phc h (PH) xm nhp c thnh phn t siu mafic n axit- kim, tui t Proterozoi sm n Paleogen. Cc thnh to magma KZ di dng cc ai mch granit porphyr, granosyenit porphyr, granit granophyr v felsit porphyr ca PH Phan Rang ( pr); hoc iabas, gabroiabas, gabroiorit porphyrit ca PH C Mng ( cm).

1.1.2.3- Kin to: G Sng Ba gm 2 t gy chnh chy song song nhng so le nhau. t gy chnh th nht nm pha ty nam, chy t Sa Thy n Sng Hinh theo phng TB-N, di 260km. t gy chnh th hai nm pha ng bc chy t Ngc Hi n Ayun Pa theo phng TB-N, di 160km, ri chuyn sang phng AVT chy ra n b bin Tuy Ho, di 120km. t gy pha ng bc nghing v pha ty nam vi gc cm khong 60-70o; t gy pha ty nam nghing v pha ng bc vi gc cm khong 70-80o. G Sng Ba c cu trc dng a

ho, c lp y cc trm tch Neogen- t. G Sng Ba hot ng trong 2 pha kin to trong Neogen- t: Pha sm (Miocen) din ra trong bi cnh ng lc nn p ngang phng AVT, hot ng trt bng tri- thun l ch yu; pha mun (Pliocen- t) din ra trong bi cnh nn p ngang phng AKT, hot ng trt bng phi- thun l ch yu, on u cui pha ng c phng AVT hot ng trt bng phi- nghch.

1.1.3- c im a mo 1.1.3.1- c im hnh thi a hnh: Trn a hnh, G Sng Ba va l

di trng thung lng gia ni hnh thnh bi tp hp cc dng a hnh ng bng tch t thm, bi bi, nn phng vt v i, ni st, va l di a hnh cao nguyn phun tro bazan tr. Bn trong G, a hnh tch t gm ch yu l bi bi, thm v cc nn phng vt ca cc thung lng sng Ia Sir, Krng P K, Ayun v sng Ba. Cao nguyn bazan c dng i ln sng thoi c cu to bi phun tro bazan Pliocen- t. Hai bn ra G ch yu phn b a hnh ni bc mn- xm thc.

1.1.3.2- c im kin trc- hnh thi cc trng Kainozoi: Dc theo G Sng Ba hnh thnh chui cc h st KZ; t trn xung bao gm: Kon Tum, Pleiku, Ayun Pa, Krng Pa v Tuy Ha. c im hnh thi- cu trc cc trng KZ c s khc bit v kch thc, hnh thi v cu trc. Cc thnh to bin cht kt tinh, trm tch lc nguyn, phun tro v xm nhp c tui t Tin Cambri ti Mesozoi l lin tc ven ra v y cc trng.

1.2- Lch s nghin cu a cht Kainozoi Lch s nghin cu a cht KZ G Sng Ba gn lin vi lch s nghin cu

a cht khu vc Nam Trung b, c th chia lm hai giai on: - Giai on trc 1975: Cc nh a cht Php mi ch khc ho nhng nt c

bn v cu trc v phn chia s b mt s thnh to a cht trc KZ. Cc nghin cu ca Colani M. (1919), Saurin E. (1935) cp n s c mt ca cc thnh to Neogen Nam Trung b. Fromaget J. (1937), Saurin E. (1956) m t v phn chia s b cc thnh to t.

- Giai on sau 1975: Sau nm 1975, cng tc nghin cu a cht KZ gn lin vi cc cng trnh o v bn a cht cc t l khc nhau. Tuy cn tn ti khc nhau v khi lng v tui a cht, nhng cn bn c s nh hnh v a tng KZ vng nghin cu.

Fontaine H. (1978) xc nh s c mt ca cc thnh to Paleogen-Neogen vng Di Linh. Nguyn ch D, Nguyn Xun Bao, Cng D (1980) t cc kt qu nghin cu cc thnh to Neogen Nam Trung b v tp hp bo t phn hoa (BTPH) xut thang a tng trong khu vc. Trn c s kt qu nghin cu cc phc h c thc vt Trnh Dnh xc lp cc HT Sng Ba, HT Kon Tum. Cc tc gi Atlas a tng Vit Nam (1982) a ra s lin kt a tng cc thnh to Paleogen- Neogen da trn phn tch tng- trm tch. Nguyn ch D (1987) a ra s phn chia v i snh cc thnh to KZ trn ton lnh th Vit Nam. V

vi c sinh c cc cng trnh nghin cu v BTPH ca Nguyn ch D; v Diatomeae ca o Th Min, ng c Nga, v Foraminifera ca Nguyn Ngc, Ngoi ra, Nguyn c Thi (1988) cng xc lp ip Cheo Reo c tui Miocen (N1 cr) v lin h a tng trm tch Neogen khu vc bc Ty Nguyn

Hin ang tn ti nhiu quan im khc nhau v tui hnh thnh trm tch KZ G Sng Ba. HT Sng Ba c Trnh Dnh, Trn Tnh, V Khc, Tng Duy Thanh xp vo tui Miocen mun (N13) da theo ha thc vt v BTPH. Nm 1982, cc tc gi n Atlas a tng Vit Nam, phn thp ca HT Di Linh c xp vo HT Ph Tc vo tui Miocen gia (N12). Trong Cc phn v a tng Vit Nam do Tng Duy Thanh, V Khc (2006) ch bin, HT Sng Ba c xp vo tui Oligocen (E3) cn HT Kon Tum c xp vo Miocen (N1). Trong a cht v Ti nguyn Vit Nam nm 2009, Trn Vn Tr v V Khc xc nhn li tui Miocen mun ca HT Sng Ba (N13 sb) v Pliocen ca HT Kon Tum (N2 kt).

Trong o v bn a cht, cc phn v a tng t c cc tc gi phn chia kh chi tit v xc lp mi quan h gia chng vi cc bc thm sng trong khu vc. Tuy nhin, vn cn nhiu tn ti trong vic phn chia gia cc nhm t khc nhau v khi lng, tui thnh to. Cc thnh to t khu vc Tuy Ho cn c nghin cu qua cc cng trnh ca Nguyn ch D (1995), Trnh Nguyn Tnh v V Vn Vnh (1998), Ng Quang Ton (2000),.. Cc phn v a tng t c phn chia trn c s gn lin vi cc chu k trm tch trong t.

Tm li, cc nghin cu trc y mc d t c nhiu thnh cng, nhng cn mt s vn tn ti: Cc phn v a tng KZ cha c s thng nht v khi lng, v tui; gia cc tc gi v gia cc nhm t; nghin cu v thnh phn vt cht, tng trm tch, chu k tch t trm tch,... cn thiu chi tit.

Chng 2- PHNG PHP LUN V PHNG PHP NGHIN CU 2.1- Phng php lun 2.1.1- Khi nim chung v a tng hc: a tng hc l khoa hc v cc

lp , khng ch quan tm n trnh t ban u v quan h v tui ca cc th m cn quan tm n s phn b, thnh phn thch hc, tp hp ho thch v cc tnh cht a vt l, a ho- tc l tt c cc c tnh v thuc tnh c th theo di c ca cc th v ngha ca chng v mt mi trng, kiu ngun gc v lch s a cht.

2.1.1.1- C s l lun v thch a tng: Trong lun n, NCS s dng h thng phn loi thch a tng phn chia a tng cc thnh to KZ.

a- Khi nim: Phn v thch a tng l mt tp hp cc lp c cng mt c im thch hc hoc mt t hp cc loi c thnh phn thch hc tng t nhau c th d dng phn bit vi cc tp hp khc trong mt ct a cht ngoi thc a. Nh vy, phn v thch a tng c th ch gm mt trong cc loi trm tch, ngun ni la, bin cht hoc t hp ca cc loi cho d chng cn b ri hay b gn kt. Vic xc lp phn v thch a tng c th p dng cho tt c cc

loi phn lp c tui t Tin Cambri n t. b- H thng phn loi: H thng cp bc t ln n nh ca cc phn v thch

a tng gm: lot, h tng, tp, lp (h lp); trong , h tng l phn v c bn ca h thng phn loi thch a tng. nc ta, i vi trm tch t, cc phn v a tng c phn chia da trn tui v ngun gc. Nhiu kiu ngun gc c cc tc gi xp vo phn v Trm tch vi ngun gc i km c hm coi nh l mt phn v thch a tng, tng ng vi phn v H tng.

c- Nguyn tc phn chia: Trong lun n ny NCS s dng nguyn tc phn chia cc phn v a tng trm tch theo nguyn tc ngun gc v tui: Cc thnh to trm tch cng ngun gc v tui c xp vo cng mt phn v. Cc thnh to cng tui nhng khc ngun gc v ngc li, cng ngun gc nhng khc tui th c xp vo cc phn v a tng ring bit. Quy tc xc lp v t tn mt phn v a tng mi c xc nh r trong Chng 6 ca Quy phm a tng Vit Nam nm 1994.

2.1.1.2- C s l lun v thi a tng a- Khi nim: Phn v thi a tng l cc th a cht gm cc c thnh

to trong mt thi gian a cht xc nh ca lch s thnh to v tri t. Bn cht ca phn v thi a tng l da trn tiu chun v thi gian thnh to phn v m khng cn c vo thnh phn v b dy ca n cc a phng khc nhau. Gii hn trn v di l cc b mt ranh gii ng thi.

b- H thng phn loi: Theo Quy phm a tng Vit Nam, h thng cp bc cc phn v thi a tng quc t vi cc cp tng ng gia a tng v a thi nh sau: Lin gii- Lin i, Gii- i, H- K, Thng- Th, Bc- K, i- Thi. i vi thi a tng khu vc c cc cp tng ng l: Bc- K v H lp- Thi.

c- Nguyn tc phn chia: C s xc lp ranh gii gia phn v thi a tng trong KZ: c im c sinh; c im thch hc trm tch; c im a mo- tn kin to; c im c kh hu,...

NCS s dng thang a tng c cc im cn lu sau: Ranh gii gia cc h Neogen v t l 1,806 triu nm; gia cc thng Pleistocen v Holocen l 11.700 nm. Thng Pleistocen gm 3 ph thng: Di (Q11), gia (Q12), trn (Q13) vi cc ranh gii tng ng gia chng l 700.000 nm, 125.000 nm. Thng Holocen gm 3 ph thng: Di (Q21), gia (Q22), trn (Q23). Ranh gii gia Q21 vi Q22 l 6.000 nm, gia Q22 vi Q23 l 3.000 nm.

2.1.2- Giai on v ph giai on pht trin cc thnh to Kainozoi Cc thnh to Kanozoi trong khu vc G Sng Ba bao gm cc thnh to

trm tch, trm tch- phun tro v cc thnh to magma xm nhp c tui Kainozoi. Lch s pht trin cc thnh to Kainozoi c hiu l lch s pht trin cc hot ng magma (xm nhp v phun tro) v cc hot ng tch t trm tch trong khu vc. Lch s pht trin cc thnh to Kainozoi G Sng Ba c phn chia thnh cc giai on (G) v ph giai on (PG).

- G pht trin c gii hn bi cc khong thi gian khi u v kt thc cc hot ng magma v tch t trm tch c tnh cht khu vc rng ln. G c biu hin s hnh thnh cc thnh to magma xm nhp, phun tro bazan, cc b mt bt chnh hp a tng v cc b mt san bng c quy m ln. Cc G thng din ra trn nn mt ch a ng lc nht nh v v c bn t thay i trong khong thi gian . Mt G pht trin cc thnh to Kainozoi c th gm mt hoc nhiu PG.

- PG pht trin c gii hn bi cc khong thi gian khi u v kt thc cc hot ng magma v tch t trm tch c tnh cht a phng. Cc hot ng magma v tch t trm tch trong cc PG thng din ra khng ng nht trong khng gian v chu s chi phi ca cc yu t a ng lc a phng.

Cc G v PG bao gm mt hay nhiu thi k pht trin. Mi thi k pht trin tng ng vi khong thi gian thnh to mt phn v a cht Kainozoi (phc h magma, h tng hoc tp thch a tng). Mi thi k thnh to c nhng c im ring v iu kin c a l, c im bn tch t, c kh hu, c mi trng,...

2.2- Phng php nghin cu a tng KZ G Sng Ba c phn chia cc phn v thch a tng da

trn nguyn tc ngun gc v tui nn cc phng php nghin cu thnh phn vt cht v tng trm tch l cc phng php ch o. NCS s dng cc phng php nghin cu chnh: (1) Phng php m t nghin cu thc a; (2) Phng php nghin cu thnh phn thch hc; (3) Phng php phn tch thnh phn ht; (4) Phng php phn tch thnh phn khong vt; (5) Phng php phn tch tng trm tch; (6) Phng php phn tch c sinh; (7) Phng php xc nh tui tuyt i; (8) Phng php lin kt i snh a tng; (9) Phng php phn tch a mo.

Chng 3- A TNG KAINOZOI I T GY SNG BA Cc thnh to KZ G Sng Ba phn b ch yu trong cc trng tch t phn

b dc theo G, t trn xung gm: Kon Tum, Pleiku, Ayun Pa, Krng Pa v trng ven bin Tuy Ha. a tng KZ G Sng Ba bao gm 23 phn v a tng c tui t Miocen gia- mun n hin i; c m t theo trt t ca thang a tng nh sau:

H Neogen Cc trm tch Neogen phn b cc trng Krng Pa, Ayun Pa, Pleiku v Kon

Tum; bao gm cc phn v a tng sau: Thng Miocen, Ph thng Miocen gia-trn H tng Sng Ba (N12-3 sb) phn b ti cc trng Krng Pa v Ayun Pa. Mt

ct ca HT c xc nh qua cc l khoan LK1- Enreca Ph Cn, LKC70 Ph Thin, LK314 Ayun Pa v cc mt ct sui Ea Rsai, cu L Bc, sng C Li, sui Ea Thul. Mt ct HT Sng Ba gm 2 tp, t di ln gm:

- Tp 1: Xen k dng nhp gia cui kt cc c ht vi sn kt v ct kt c cha cc thu knh st bt kt mu xm trng, xm xanh xen t xm nu ven ra

chuyn sang ct kt cha cc v thu knh ct th xen k vi st- bt, st kt mu xm xanh v cc lp than nu trung tm vng trng. Dy t vi chc m ti 150m. Cha phong ph cc di tch thc vt v BTPH.

- Tp 2: Ct sn kt cha cc thu knh cui kt, ct kt, ct bt kt, st kt xen k cc lp than nu phn b dng nhp. c mu xm trng chuyn ln xm xanh, xm vng v loang l cui mt s nhp. Cng ln trn thnh phn mn trong nhp cng dy, nhiu ni cha cc lp st than v cc thu knh than nu. Dy t 50-250m. Cha phong ph di tch thc vt v BTPH.

Trnh Dnh xc nh c 2 phc h thc vt, t di ln: Quercus- Laurus vetusta- Ficus beauveriei v Ficus beauveriei- Dipterocarpus- Cassia phaseolites tiu biu cho thc vt rng cn nhit i m v cn nhit i nng m, c tui N13. Nguyn ch D (1987) xc nh c mt phc h BTPH tui N12-3.

HT Sng Ba ph khng chnh hp trn trn cc thnh to trc KZ v c HT Bun Tu tui Pliocen nm khng chnh hp ln trn.

Thng Pliocen Bao gm HT Bun Tu v HT Kon Tum, trong HT Bun Tu mi c NCS

xc lp trong lun n ny. H tng Bun Tu (N2 bt) c NCS xc lp trn c s tch khi lng tp 3

cha tuf, Diatomeae, trepen v bentonit ca HT Sng Ba c NCS m t trc y. HT Bun Tu phn b cc trng Krng Pa, Ayun Pa v din nh Cng Sn. C th gp chng ti cc mt ct Bun Tu, o Ch S,... v trong cc l khoan LK1- Enreca, LK390, LK755,... vng Krng Pa hay cc l khoan LKC70, LK1, LK4, ... vng Ayun Pa. Mt ct chung ca HT Bun Tu gm 3 tp t di ln:

- Tp 1: Cui kt, sn kt xen ct kt cha cui ht nh mu xm trng chuyn ln trn l ct kt ln sn si nh, bt st kt lun phin xen k nhau dng nhp. Trong trm tch cha nhiu vt liu tuf ni la, st cha bentonit n cc thu knh bentonit, lp mng st than, than nu. Dy 5-10m n 200m (ti LK1- Enreca).

- Tp 2: Bt kt, st kt, st iatomit- trepen mu xm xanh, xanh en hoc nu xen kp cc va than nu; i ch xen kp cc lp ct sn kt; chuyn ln trn l ct sn kt mu xm tro, xm xanh xen kp cc lp ct kt, bt kt tuf, st bt kt tuf. Cha Diatomeae, nhiu BTPH v To nc ngt. Dy t 30-60m.

- Tp 3: Cui kt, ct sn kt, ct kt, bt kt mu nu vng, st bt kaolin mu xm trng, st kt xm xanh, xm nu, loang l cu to dng nhp, cha nhiu vt in l cy. cha cc kt hch, kt vn vi silic v du vt hot ng ca sinh vt. Cc vt in l cy thuc phc h sinh thi rng cn nhit i n ha c khong tui Neogen cng cc dng BTPH v t To thuc mi trng lc a. Dy t 10m n 30m.

Tui Pliocen ca HT c xc nh da vo tui ca phc h thc vt Quercus advena- Ficus beauveriei do Trnh Dnh thu thp c khu vc bn Ai Nu v To Diatomeae gm: Auracosira granulata, A. islandica, A. praegranulata, A. cf.

jouseana. HT Bun Tu nm khng chnh hp trn tp 2 ca HT Sng Ba v cc thnh to c hn trong khu vc. HT Bun Tu b phun tro bazan HT Tc Trng v Xun Lc ph khng chnh hp ln trn.

H tng Kon Tum (N2 kt) phn b rng ri trng Kon Tum v cc din nh trng Pleiku. Ti trng Pleiku, trm tch ca HT b ph di lp ph bazan KZ dy t hng chc n hng trm mt. Mt ct HT gm:

- Tp 1: Cui sn kt, ct kt a khong mu xm; chuyn ln trn l ct kt, sn kt thch anh. Ti mt s ni c xen kp cc lp mng bazan c st, bazan l hng v tuf ca chng. Chiu dy tp t 8-10m n 60m. Cha di tch thc v ng vt thn mm. Phc h thc vt Quercus advena- Ficus beauveriei thuc kiu rng cn nhit i n ha. Phc h to silic Melosira- Cyclotella mi trng nc ngt c tui N21.

- Tp 2: St kt mu xm en, xm xanh, chuyn ln trn c mu vng ngh, c cha iatomit, phn lp nm ngang, nn p cng; i ch cha lp mng st bentonit mu xm xanh. Dy t 5-10m n 60-70m. Cha phong ph to Diatomeae v ha thch l cy. Phc h thc vt Arbutus elegans kiu rng n ha na kh hn. Phc h to silic Melosira- Stephanodiscus a kim sng trong mi trng ngt- l tui N22.

- Tp 3: St, st bt kt mu xm vng loang l, xen lp mng ct sn kt, st kaolin pha ct, nn p kh cng. Chuyn ln trn l bt st kt, ct sn kt b laterit ha, gn kt chc. Dy t 5-7m n 15-20m. Cha BTPH, to silic v t to khng r ngun. Cc dng thc vt thuc kiu rng cn nhit i nng m. Phc h to silic Melosira- Eunotia sng trong mi trng nc ngt, tui N23.

HT Kon Tum ph ln trn c trc Kainozoi v b bazan HT Tc Trng v cc thnh to trm tch t b ri ph ln trn.

Thng Pliocen - Thng Pleistocen, ph thng di H tng Tc Trng (N2-Q11 tt): C din l v chim khi lng ln trong

cc thnh to KZ khu vc G Sng Ba. Gm 2 kiu mt ct: *Kiu mt ct phun tro c pht hin ti l khoan LK121 Tr B. Mt ct

gm 4 tp tng ng vi 4 pha hot ng ca ni la: (1) Tp 1: Dm kt ni la mu xm, cu to khi xen k cc lp bazan c st v bazan l hng. Phn trn cng b phong ho; dy 40,7m. (2) Tp 2: Dm kt ni la mu xm n xm sm, cu to khi xen k vi bazan c st. Phn trn b phong ho yu; dy 61,2m. (3) Tp 3: Bazan c st mu xm tro, cu to khi rn chc. Phn trn dy b phong ho thnh st mu nu ; dy 119,1m. (4) Tp 4: Bazan l rng chuyn ln bazan c st mu xm, cu to khi rn chc. Phn trn cng b phong ho thnh bt- st; dy 29,3m.

B dy chung ca HT ti l khoan LK121 l 250,3m. H tng ph trc tip ln HT Kon Tum. Ranh gii trn chuyn ln bazan HT Xun Lc.

*Kiu mt ct phun tro xen trm tch phn b trong cc bn tch t nh c ghi nhn ti l khoan LK116 Bin H. Mt ct t di ln gm: (1) Tp 1: Bazan l

hng mu xm en xen kp bazan c st, rn chc; phn trn b phong ho thnh st bt nu ; dy 58,5m. (2) Tp 2: Bazan c st mu xm en, dng khi rn chc; dy 13,3m. (3) Tp 3: St kt mu xm tro phn lp mng, gn kt yu; phn trn l ct kt thch anh ht nh n th, gn kt yu; dy 27,5m. (4) Tp 4: Bazan c st mu xm en, rn chc; chuyn ln trn l bazan l hng mu xm nu; phn trn cng b phong ho; dy 90m.

HT Tc Trng ph khng chnh hp thnh to c hn v b HT Xun Lc ph ln trn. Kt qu phn tch BTPH trong st bt kt xen kp Bu Cn cho tui Pliocen. Gi tr tui tuyt i ca HT ti An Ph l 2,1 triu nm v Ch S l 1,58 v 1,75 triu nm ng vi Pliocen- Pleistocen sm.

H t Bao gm 2 nhm ngun gc khc nhau: Nhm tng chuyn tip lc a- bin

trng Tuy Ho v nhm tng lc a cc trng cn li. Thng Pleistocen Ph thng Pleistocen di- gia Trm tch sng (a,apQ11-2) phn b ven ra cc trng Krng Pa, Ayun Pa v

Kon Tum; gm 2 kiu mt ct: * Kiu mt ct trm tch sng phn b ti trng Krng Pa v Ayun Pa. Mt ct

chung t di ln gm: (1) Tp di: Cui, tng, sn si, ct mu xm vng loang l; dy 0,8-1,5m. Ph trc tip ln trn cc thnh to trc t. (2) Tp gia: Sn si, ct mu xm nu, i ch b laterit ha gn kt cng chc; dy 0,1-0,4m. (3) Tp trn: Ct, bt ln sn si gn kt cht, mu vng nu loang l; dy 0,5-1m.

B dy chung ca trm tch 0,5-5m. Trong ct bt ca tp trn ti Ch e H, Ayun Pa c cha BTPH.

* Kiu mt ct trm tch sng- l phn b trng Kon Tum, mt ct t di ln gm: (1) Tp di: Cui sn si a khong, kch thc 1-10cm, chuyn ln ct th, sn si mu nu vng; dy 6,26m. Tp ph ln trn cc thnh to trc t. (2) Tp gia: St bt, ct mn mu loang l tm hng. Phn trn gm bt st kaolin mu trng c b laterit ho loang l vng, nu ; dy 11m. (3) Tp trn: Bt st, ct ln t sn si mu nu nht; dy 7,5m.

Chiu dy chung ca mt ct l 24,6m. Cha BTPH c trng cho kh hu nng m nhit i, mi trng nc ngt. Trm tch aQ11-2 cu to nn thm sng bc IV h thng sng Ba. Trm tch apQ11-2 cu to nn thm sng bc III h thng sng S San.

Trm tch sng- bin (amQ11-2) tng ng vi khi lng ca HT Tuy Ho do Trn Tnh, V Vn Vnh xc lp nm 1994. Trm tch amQ11-2 khng l ra trn b mt m ch bt gp cc l khoan LK02-500 v TH2 Ph Lm. Mt ct ti l khoan TH2 gm: (1) Tp di: Ct cha sn pha bt st, ct pha bt st ln sn mu xm xanh; dy 8,5m. (2) Tp trn: Bt st mu xm en, mn do xen cc lp mng ct ht mn dng thu knh; dy 21,0m. Cha phong ph Foraminifera, ngho

BTPH. B dy chung ca mt ct l 29,5m. Trm tch amQ11-2 nm ph khng chnh

hp ln v phong ho cc thnh to trc KZ v b ph bi trm tch amQ12-3 c tui ng v C14 l 39.000 nm.

Ph thng Pleistocen gia H tng Xun Lc (Q12 xl) c Nguyn c Thng xc lp nm 1999.

Bazan HT Xun Lc phn b trung tm trng Pleiku, cc chm nh Sn Thnh v Cng Sn. Mt ct ca HT c 2 tng:

Tng phun tro pht trin rng ri vi mt ct y ti l khoan LK121 (Tr B) su t 0-149,7m. Thnh phn ton bazan, ch yu l bazan l hng xen bazan c st. mt ct ny gp 6 b mt v phong ho bazan tng ng vi 6 nhp phun tro. Chiu dy ca mt ct khong 150m.

Tng phun n phn b k cn st ming ni la. Mt ct c trng cm l khoan LK104 ti Hi Ph, TP. Pleiku. Thnh phn gm cc lp fuf v dm vn ni la vi thnh phn dm l bin cht, granit,.. xen k cc lp bazan c st v bazan l hng. B dy ln hn 135m.

Bazan HT Xun Lc ph trc tip trn bazan HT Tc Trng. HT c nh tui Q12 da vo tui ng v ca cc mu vng Xun Lc l 0,7 triu nm.

Ph thng Pleistocen gia- trn Trm tch sng (aQ12-3) phn b dc theo cc thung lng sng Ba v sng S

San cc trng Krng Pa, Ayun Pa, Kon Tum v khng c mt trng Pleiku. Mt ct c trng gm: (1) Tp di: Sn si, ct mu vng, b ri, y cha cui tng; dy 4,4m. (2) Tp gia: Sn si, ct xen k cc lp ct bt loang l; dy 8,1m. (3) Tp trn: Bt ct mu xm vng, gn kt yu; dy 1,5m. Cha ngho nn BTPH.

Ti thm II thung lng k Ter, xc nh c tp hp BTPH: Murtus sp., Myrica sp., Compositae gen. indet c tui aQ12-3. Trm tch cu to nn thm xm thc tch t bc III dc h thng sng Ba v thm bc II dc h thng sng S San. Chng ph trn cc thnh to trc t v b cc trm tch tr hn ph ln trn.

Trm tch sng- bin (amQ12-3) phn b ven ra trng Tuy Ha hoc di cc l khoan. Mt ct trm tch amQ12-3 t di ln gm: (1) Tp di: Sn si ct cha cui, t bt mu xm nu loang l; dy 4,9m. (2) Tp trn: St bt mu nu vng, mn, do. Cha t v s c nguyn dng v t r thc vt; dy 1,7m

B dy chung ca mt ct l 6,7m. Tp hp BTPH ngho nn. Tui ca trm tch amQ12-3 c xc nh da trn mi quan h a tng vi trm tch amQ11-2 nm di v tui ng v C14 ca tp trm tch ph l 39.000 nm.

Ph thng Pleistocen trn Trm tch sng (aQ13) phn b kh rng ri, di dng thm sng bc II dc

theo cc thung lng sng Ba hay cc bc thm sng bc I ca h thng sng S San. Mt ct gm: (1) Tp di: Cui tng, sn si cha tectit mu trng c nu vng, nn cht, b laterit ho yu; dy 1-2,5m. (2) Tp gia: Sn si, ct cha t bt st mu xm

vng; dy 1,5-2,5m. (3) Tp trn: Ct bt ln sn si mu xm vng, xm trng; dy 0,5-2m. Cha phong ph BTPH c trng cho vng ng bng nhit i, c tui Q12-Q13.

Trm tch aQ13 ph bt chnh hp trn cc c hn. Kt qu phn tch C14 trong thm I sng k Psi cho tui 12.000 250 nm; ti p k Ta cho khong tui >40.000 nm.

Trm tch sng- bin (amQ13) l ra Ho Quang, M Cnh v c quan st thy trong hng lot cc l khoan trng Tuy Ha. Mt ct c trng gm: (1) Tp di: Ct pha bt cha sn mu xm, xm trng dnh kt kh cht chuyn ln ct pha sn ln bt b ri xm xanh, pht en; dy 8,0m. (2) Tp trn: Bt st xm xanh pht en gn kt cht, kh cng chc, phn trn ln cc ct nh; dy 6,7m.

B dy ca mt ct t 13,5m. Cha tp hp BTPH thng gp trong Q13. Trm tch amQ13 ph ln trn trm tch amQ12-3 v b ph bi cc trm tch Q21-2.

Thng Holocen Ph thng Holocen di- gia Trm tch sng (aQ21-2) c din phn b rng, to thnh bc thm sng bc I

dc thung lng h thng sng Ba v bi bi cao trn h thng sng S San. Mt ct chung t di ln gm: (1) Tp di: Cui, sn si, ct a thnh phn; dy 3m. (2) Tp gia: St bt pha ct loang l xanh vng hoc xm nu, xm en. Cha nhiu xc thc vt v to nc ngt- l; dy 2-10m. (3) Tp trn: Ct bt mu mu xm vng, xm en, b laterit ho yu. Cha to Diatomeae dng nc ngt- l v Silicoflagellata dng nc ngt; dy 0,4-3,6m.

trng Krng Pa cha BTPH Polypodiaceae c tui Q13-Q21. Kon Tum cha BTPH tui Q21. Trm tch aQ21-2 ph bt chnh hp trn trm tch Q13 v cc thnh to c hn. Tui tuyt i mu trng Krng Pa cho kt qu C14 = 6.100 300 nm.

Trm tch sng- bin (amQ21-2 ) l ra khu vc Ho Quang, Thch Bn. Phn cn li ca chng nm su xung ng bng v ch c thy qua cc l khoan su. Mt ct h tng ti l khoan KT2-T.XIV nh sau: (1) Tp di: Ct cha sn mu vng nht n xm vng, b ri; dy 3,0m. (2) Tp gia: Ct sn chuyn ln ct mn pha bt st mu loang l, lm m vy mica, dnh kt yu; dy 6,0m. (3) Tp trn: Bt st pha ct mu xm en, nu t hi b loang l; trm tch do mn, khi kh cng chc; dy 2,0m. Cha to nc ngt, nc mn, nc l v phc h BTPH. Trm tch amQ21-2 ph ln trn cc thnh to c hn v b cc thnh to tr hn ph ln trn.

Trm tch vng bin (mlQ21-2) ch quan st c qua cc l khoan Tuy Ha. Mt ct ti l khoan LK51 t di ln gm: (1) Tp di: Ct ln sn mu xm trng pht vng chuyn ln ct pha bt st mu xanh en cha di tch thc vt, mnh vn v s vn nt; dy 2,8m. (2) Tp trn: Bt st cha mnh v s c mu en mn do; dy

10,5m. Trong tp trn c cha nhiu di tch v s c gm cc dng: Placuna placenta (Lin.), Dentalium sp., Balanus sp..

Trong trm tch cha rt nhiu di tch vi c sinh, BTPH v to. Trong khng gian, trm tch c s chuyn tng ngang vi trm tch amQ21-2 v trm tch mbQ21-2. Tui ng v C14 xc nh trn v s tp trn cho cc tui t 6.40070 nm n 8.000115 nm.

Trm tch doi ct bin (mbQ21-2) phn b thnh di cn ct ko di dc b bin Tuy Ha hoc trong cc l khoan. Mt ct ti l khoan TH7-T.II gm: (1) Tp di: Ct cha sn chuyn ln ct ln sn mu xm vng, b ri, cha v s c; dy 11,3m. (2) Tp trn: Ct thch anh ht trung mu xm vng b ri, chn lc tt, mi trn trung bnh; dy 5,5m.

Trm tch cha kh nhiu Foraminifera. Trm tch mbQ21-2 c quan h chuyn tng vi trm tch mlQ21-2. Tui ng v C14 ca v s c ly ti phn y ca tp 1 t gi tr 6.215100 nm.

Ph thng Holocen trn (Q23) Cc trng lc a hnh thnh cc trm tch sng v sng- m ly. trng Tuy

Ho c nhiu kiu tng khc nhau, to thnh mt dy trm tch bin thoi sau bin tin cc i Holocen gia; bao gm cc trm tch sng, sng- m ly, doi ct bin (bar), bin v gi sinh.

Trm tch sng- m ly (abQ23) c din phn b rt rng ri ng bng Tuy Ha. Mt ct t di ln ton l bt st mu xm xanh, xm en cha mn thc vt, do mn. Dy t 1-2m n 8-9m. Ngho BTPH, t to nc ngt.

cc trng lc a, trm tch abQ23 phn b thnh cc di hp lin quan vi a hnh thung lng kn, na kn hoc trn cc h mng nga, on sng b thoi ha. Mt ct trm tch gm ct sn, ct st, st bt mu xm, xm en cha mn thc vt cha ha than hon ton; i ni to thnh cc thu knh than bn. Dy 1-5m.

Trm tch sng (aQ23) c 2 kiu mt ct: * Mt ct khu vc min ni cu to nn cc bi bi cao dc cc sng sui ln;

t di ln gm tp: (1) Tp di: Cui, sn si, ct mu xm vng. Cui c kch thc 1-2cm, a thnh phn, mi trn tt; dy 2,5m. (2) Tp gia: Ct b ri xen cc lp ct- bt st mu xm en cha xc thc vt; dy 2-3m. (3) Tp trn: Ct cha t bt st mu xm vng; dy 1,0-1,5m.

* Ti trng Tuy Ho, mt ct t di ln gm 2 tp: (1) Tp di: Ct cha sn mu trng pht vng, b ri xen cc lp mng ct trung ln sn; dy 12m. (2) Tp trn: Ct pha bt ln sn mu trng vng, dnh kt yu; dy 3m. Cha to silic. Mt ct trm tch bi bi thp v lng sng c xu th gim dn kch thc ht trung bnh t di ln trn. B dy thay i t 5-11m.

Trm tch sng- bin (amQ23) phn b ca sng Nng. Mt ct c thnh phn ct sn mu xm xanh, chn lc km. Thnh phn khong vt ch yu l thch anh, t mnh v fenspat. Trong trm tch amQ23 c cc loi to nc mn. B dy

ca thnh to ny thay i khong 4-5,5m. Trm tch amQ23 ph ln trn trm tch doi ct bin tui Q21-2.

Trm tch doi ct bin (mbQ23) l ra trn b mt dc ven bin Tuy Ha. Mt ct thng c 2 tp: (1) Tp di: Ct ln sn xen cc lp ct mng, chuyn ln ct cha sn xen vi ct ln sn mu xm, xm trng b ri; dy 2,3m. (2) Tp trn: Sn pha ct chuyn ln ct cha sn, ct ln sn b ri mu xm nu nht n vng nht; dy 10,5m. Cha rt nhiu ha thch vi c sinh. Cc thnh to trm tch mbQ23 c s phn d thch hc t kiu i triu thp ln i triu cao, to mt ct bin thoi ph chng gi ln cc thnh to doi ct bin tui Q21-2 ni cao v b gi ti to.

Trm tch bin (mQ23) phn b ko di dc ng b bin, t Bnh Kin n Phc Tn, phn b t nh sng triu cao tr ra. Thnh phn ch yu l ct, ct cha sn ln mnh san h, s c mu xm, xm vng, b ri, chn lc tt. Thnh phn khong vt to chnh l thch anh, t mnh v fenspat.

Trm tch gi sinh (vQ23) phn b thnh cc cn ct c dng khng cn xng, cao 8m n 10m khu vc ven bin trng Tuy Ha. Thnh phn gm ct thch anh ht trung n mn mu xm vng, xm nht, gn kt yu, ri rc. Thnh phn cp ht ct chim 100%. Dy 4-10m. Trm tch ny ph ln trm tch amQ21-2 v trm tch mbQ21-2.

H t khng phn chia Trm tch sn- l tch (dpQ) bao gm cc thnh to proluvi, deluvi,

coluvi,.. phn b cc chn sn ni hoc cc b mt di chn cc di ni. Thnh phn gm: dm sn, cui, tng, ct bt, chn lc km- trung bnh, mi trn km. Chiu dy 1-7m. Chng thng ph ln trn b mt phong ho gc trc t.

Trm tch h (lQ) gp trong cc phu ming ni la m c kch thc khc nhau rt pht trin trong trng Pleiku v pha nam trng Kon Tum. Thnh phn trm tch ch yu l st, st bt cha mn thc vt, phn thp thng ln t dm sn; i ni c thu knh than bn mng. Chiu dy thay i t 5-7m n 23m. Trm tch h tui t khng phn chia ph trc tip trn v phong ha bazan thuc cc HT Tc Trng v Xun Lc.

T nhng kt qu phn chia chi tit a tng trn cho thy: (1) Cc thnh to KZ G Sng Ba a dng v phc tp, bao gm 23 phn v a tng c tui t Miocen gia n hin i; (2) Cc phn v a tng KZ G Sng Ba c nhiu ngun gc khc nhau: lc a, lc a- phun tro, phun tro v lc a- bin; (3) H tng Bun Tu c tui Pliocen (N2 bt) ln u tin c xc lp, phn b cc trng Ayun Pa v Krng Pa; (4) Thang a tng KZ ti cc trng ring bit phn nh tnh cht pht trin khng ng nht ca cc bn tch t trn G Sng Ba trong KZ.

Chng 4- LCH S PHT TRIN CC THNH TO KZ G SNG BA Lch s pht trin cc thnh to KZ G Sng Ba c ti dng trn c s

nghin cu chi tit v a tng cc thnh to trm tch v phun tro KZ, cc hot ng

magma xm nhp KZ trong khu vc v lin h, i snh vi cc thnh to KZ phn b trong cc bn trng trn thm lc a k cn. Lch s pht trin cc thnh to KZ G Sng Ba gm 3 G: Paleocen- Eocen, Oligocen- Miocen v Pliocen- t. Mi G c th gm cc PG vi nhiu thi k c lch s pht trin ring bit to nn s phn d v thnh phn vt cht, iu kin thnh to ti cc khu vc khc nhau trn ton G.

4.1- Giai on Paleocen- Eocen: G Paleocen- Eocen c c trng bi qu trnh xm thc bc mn mnh

m trn nn hot ng to ni, hot ng magma xm nhp hot ng tch cc v s vng mt trm tch trn phm vi G Sng Ba. Hot ng to ni trong Paleocen- Eocen hnh thnh nn cc ai mch gabro- iaba phc h C Mng v granit porphyr phc h Phan Rang rt ph bin trong khu vc Nam Trung b. Hot ng bc mn xm thc mnh m pht trin trn ton b khu vc lnh th Nam Vit Nam, trong c vng nghin cu, hnh thnh nn b mt san bng (BMSB) ng Dng tui Paleogen gia c cao 1.500-2.500m. Qu trnh trm tch hon ton vng mt trn phm vi G. Tch t trm tch ch c hnh thnh trn khu vc thm lc a ln cn: bn trng Ph Khnh, Cu Long, Nam Cn Sn v c lp y bi cc thnh to trm tch lc a nh cc h tng C Ci (E2 cc), C Lao Dung (E2 cld),.. tui Eocen phn b y cc bn trng.

Cc hot ng kin to mnh m vo cui Eocen hnh thnh nn mt b mt khng chnh hp a tng kh r nt trn cc thnh to trm tch Eocen ti cc bn trng trn thm lc a k cn.

4.2- Giai on Oligocen- Miocen: c trng c bn ca G Oligocen- Miocen l cc hot ng bc mn, xm

thc v tch t trm tch din ra trn nn hot ng magma ngng ngh trn ton b khu vc nghin cu. G Oligocen- Miocen bao gm 2 PG: Oligocen- Miocen sm v Miocen gia- mun. S khc nhau c bn gia 2 PG ny l s chuyn tip t qu trnh bc mn xm thc thng tr sang qu trnh tch t trm tch trong cc bn trng nh hp lin quan ti hot ng khi pht ca G Sng Ba vo khong cui Miocen sm.

4.2.1- Ph giai on Oligocen- Miocen sm: Hot ng xm thc bc mn mnh m tip tc xy ra, b mt san bng ng

Dng tip tc b ph hy. Trn phm vi G Sng Ba hon ton vng mt qu trnh tch t trm tch Oligocen- Miocen sm. Hot ng tch t trm tch ch din ra ti cc bn trng ti thm lc a ln cn nh Ph Khnh, Cu Long, Nam Cn Sn v hnh thnh nn cc HT: Tr C (E3 tc), Tr Tn (E3 tt), Cau (E3 c), Kim Long (E3 kl), tui E3; cc h tng Bch H (N11 bh), Da (N11 d), Ngc Hin (N11 nh), tui N11.

Vo khong cui Miocen sm, hot ng trt bng, nng khi tng trn phm vi lnh th Nam Trung b v vng k cn lm xut hin mt b mt khng chnh hp a tng gia cc thnh to trm tch Miocen sm v Miocen gia ti cc

bn trng trn thm lc a. Cc hot ng xm thc bc mn hnh thnh nn BMSB Lt tui Miocen sm c cao 1.400-1.800m. Trn phm vi G Sng Ba, cc t gy bt u ti hot ng vi cng yu theo kiu bng tri- thun, ph hy b mt mng c kt c trc, chun b cho s tch t trm tch vo Miocen gia- mun.

4.2.2- Ph giai on Miocen gia- mun: PG Miocen gia- mun c trng bng s hnh thnh cc trm tch lc a

thuc HT Sng Ba lp y cc bn trng Krng Pa v Ayun Pa t u Miocen gia v kt thc vo cui Miocen mun. S kt thc ca PG c ghi nhn qua mt BCH a tng a phng vi cc thnh to trm tch lc a- phun tro Pliocen. PG bao gm 2 thi k:

- Thi k Miocen gia: Vo u Miocen gia, G hot ng st ln hnh thnh cc trng st, tch gin cc b Ayun Pa v Krng Pa, qu trnh tch t trm tch tng sng- h min ni v trung du thuc tp 1- HT Sng Ba. Mi trng mang tnh kh yu. Phc h thc vt Quercus- Laurus vetusta- Ficus beauveriei thuc thm thc vt cn nhit i.

- Thi k Miocen mun: G hot ng mnh m nht thc y cc bn trm tch tip tc c m rng, tch t trm tch tng sng- h min ng bng thuc tp 2- HT Sng Ba. Mi trng mang tnh kh n kim yu. Phc h thc vt Ficus beauveriei- Dipterocarpus- Cassia phaseolites mang tnh nhit i nng m.

Hot ng kin to cui Miocen mun lm gin on trm tch, trm tch HT Sng Ba b bin v. Hot ng xm thc bc mn din ra kh mnh, hnh thnh BMSB Miocen mun.

4.3- Giai on Pliocen- t G c c trng bi s hnh thnh mi cc bn tch t trm tch Pleiku,

Kon Tum pha bc G v m rng bn tch t cc trng Ayun Pa, Krng Pa trong iu kin cc pha phun tro bazan hot ng mnh m. G Pliocen- t bao gm 2 PG:

4.3.1- Ph giai on Pliocen- Pleistocen sm: c trng bi s hnh thnh mi cc bn trng Pleiku, Kon Tum v s thng

tr ca hot ng phun tro bazan ko di sut PG. - Thi k Pliocen sm: Hot ng phun tro bazan din ra mnh m trn ton

vng Nam Trung b, hnh thnh nn tp 1- HT Tc Trng ph bin nhiu ni. Ti Ayun Pa v Krng Pa, tch t trn bn trm tch Miocen c trc hnh thnh nn trm tch tng sng- h min ng bng thuc tp 1- HT Bun Tu. Ti Kon Tum v Pleiku bt u hnh thnh cc bn tch t mi dc G trn BMSB Miocen mun b ph hu, tch t trm tch tng h cnh quan ni la thuc tp 1- HT Kon Tum. Mi trng mang tnh kh ti cc trng Ayun Pa, Krng Pa v mang tnh axit yu ti cc trng Kon Tum, Pleiku. Phc h to Melosira- Cyclotella c trng cho iu kin bn trm tch c su ln. Phc h thc vt Quercus advena- Ficus beauveriei phn thp ca HT Bun Tu mang tnh cn nhit i n ha m. Ti trng Kon Tum v

Pleiku yu t thc vt h- m ly chim u th hn, th hin kh hu n ha thc th.

- Thi k Pliocen gia: Hot ng phun tro bazan cng mnh lit hn vi s gia tng thnh phn vt liu ni la trong mt ct thuc tp 2- HT Tc Trng. Trm tch tng h cnh quan ni la ht mn cha iatomit, bentonit thuc tp 2- HT Kon Tum v iatomit- trepen, bentonit thuc tp 2- HT Bun Tu c tch t. Mi trng chuyn t ch kh v kh yu thi k u sang ch kim. Phc h to Melosira- Stephanodiscus c trng cho bn trm tch a kim, c mui tng. Phc h thc vt Arbutus elegans mang tnh cn nhit i n ha na kh hn.

- Thi k Pliocen mun: Hot ng phun tro tip tc din ra, hnh thnh tp 3- HT Tc Trng. Cc bn tch t c xu hng thu hp hnh thnh nn cc lp trm tch tng h giu kaolinit thuc tp 3 cc HT Kon Tum v Bun Tu. Thnh phn vt liu phun tro v hu c ti mi bn trng u gim. Mi trng chuyn t kim sang axit c mc oxy ho cao. Phc h to Melosira- Eunotia l du hiu cho thy cc bn trng b nng dn v thu hp hn. Thm thc vt v tp hp BTPH ch th kh hu cn nhit i nng m.

Vo cui Pliocen mun, qu trnh trm tch trong cc bn trng dc G Sng Ba kt thc v phn ln din l ca chng b cc lp bazan thuc tp 4- HT Tc Trng ph ln trn ko di n thi k u ca Pleistocen sm. Ton b khu vc G c nng cao, hot ng tch t trm tch b gin on hon ton trong khong thi gian t cui Pliocen mun n ht thi k u ca Pleistocen sm. Qu trnh bc mn to nn BMSB Pliocen mun.

4.3.2- Ph giai on Pleistocen sm- Holocen: PG c trng bi qu trnh tch t trm tch lc a ti khu vc cc trng lc

a c trc v s hnh thnh v tch t trm tch lc a- bin ti trng Tuy Ha. Qu trnh trm tch trong PG din ra trong 5 thi k t cui Pleistocen sm cho n nay. Do s khc bit v iu kin tch t trm tch gia trng Tuy Ho v cc trng lc a khc nn chng c xem xt c lp.

4.3.2.1- Ph giai on Pleistocen sm- Holocen ti cc trng lc a: - Thi k Pleistocen sm- gia: Hot ng phun tro ni la ngng ngh vo

u Pleistocen sm v hot ng bc mn xm thc din ra trn ton b lnh th vng nghin cu hnh thnh nn BMSB Pleistocen sm. Qu trnh h ln din ra cui Pleistocen sm cc trng Ayun Pa, Krng Pa v Kon Tum cng ng thi bt u qu trnh tch t trm tch sng, sng- l min ni cu to nn cc bc thm sng bc IV. Mi trng trm tch c tnh axit. Kh hu nhit i nng m thng tr.

- Thi k Pleistocen gia: Vo Pleistocen gia cc bn tch t b nng ln v qu trnh xm thc bc mn pht trin hu ht cc trng. Hot ng ca G Sng Ba li c tng cng vi cc hot ng ni la phun tro rm r theo cc h thng t gy c phng AKT to nn cc lp ph bazan thuc HT Xun Lc Pleiku, Vn Ha, Cng Sn v Sn Thnh.

- Thi k Pleistocen gia- mun: Hot ng phun tro ngng ngh, cc bn trng lc a tch t trm tch sng min ni cu to nn cc bc thm sng bc III. trng Krng Pa, do G Sng Ba hot ng kh tch cc, qu trnh l v sp l xy ra mnh m, nht l cnh ng bc.

- Thi k Pleistocen mun: Ti Ayun Pa v Krng Pa mng li sng tr nn kh hon chnh, gn vi mng li sng hin i. Trm tch tng sng min chuyn tip v ng bng phn b rng ri vi mt ct trm tch sng kh hon chnh cu to nn cc bc thm sng bc II. Ti trng Kon Tum, dng chy sng t trc din cn bng, hnh thnh cc lng sng un khc b thoi ha, h mng nga b m ly ha to nn cc thu knh than bn mng. Thm thc vt ch yu l dng lau lch, c bi.

- Thi k Holocen sm- gia: G hot ng tch cc vi qu trnh nng thng tr. Qu trnh thnh to thm sng bc I pht trin kh mnh m khng ch cc trng Kon Tum, Ayun Pa v Krng Pa m c mt ti hu ht cc sng sui ln trong phm vi G. Thnh phn trm tch ht mn tng bi bi, h trn bi bi chim u th trong mt ct. Ti cc h mng nga b ly ha to cc m ly vi cc va than bn xen kp.

- Thi k Holocen mun- Hin i: Vo Holocen mun, qu trnh tch t trm tch c ngun gc lc a khc nhau vn xy ra trong cc trng vi u th ca cc thnh to sng, h, l. Trm tch sng Holocen mun thnh to cc bi bi cao vi thnh phn ch yu l ct, sn, si v cc bi bi thp v lng sng hin i.

4.3.2.2- Ph giai on Pleistocen sm- Holocen ti trng Tuy Ho Trng Tuy Ha nm u mt pha ng ca G Sng Ba c hnh thnh

do hot ng phn d khi tng v bc mn xm thc vo Pleistocen sm. Qu trnh hnh thnh chu th ven bin Tuy Ho chu nh hng ng thi ca c 2 G Sng Ba v G Tuy Ha- C Chi; trong , G Tuy Ho- C Chi ng vai tr ch o. ng lc bn tch t chu tc ng an xen ca ng lc dng chy sng, bin (sng, thy triu). Qu trnh tch t trm tch gn lin vi cc chu k dao ng mc nc bin, tng ng vi cc G gian bng v bng h trong t.

- Thi k Pleistocen sm- gia: Hu ht din tch chu th hin ti cn l vng xm thc bc mn, ranh gii ng b bin trong Pleistocen sm cch ng b bin hin i khong 5-10km. Tc ln chm ca trng Tuy Ho kh ln, to nn mt ct bin tin trm tch amQ11-2, c dy t ti 25-30m phn trung tm.

- Thi k Pleistocen gia- mun: ng b bin tin su trng vi ranh gii ng bng hin ti. Mt ct trm tch amQ12-3 th hin mt ct bin tin vi thnh phn ht mn dn t di ln trn. Hot ng ca G Tuy Ho- C Chi c xu hng cnh nam c tc h ln ln hn cnh bc, c th hin qua chiu dy trm tch cnh pha nam dy hn cnh pha bc ca G ny.

- Thi k Pleistocen mun: Bin ln rt su vo t lin. Hot ng nng h gia hai cnh ca G Tuy Ho- C Chi kh tng ng, to nn chiu dy trm tch

amQ13 hai pha G gn tng t nhau. ng bng tam gic chu Tuy Ha c hnh thnh v bi p. Vo cui Pleistocen, ton b ng bng li b cc hot ng phong ho bc mn lc a chi phi, gy nn gin on trm tch trong khong thi gian ny.

- Thi k Holocen sm- gia: Qu trnh hon thin ng bng chu th gn lin vi qu trnh tng trng ca cc doi (bar) ct bin. Mt ct tng trm tch th hin quy lut theo hng t lc a ra bin: trm tch aluvi, trm tch sng- bin, trm tch vng bin v trm tch doi ct bin. Chu nh hng h ln cnh nam ca G Tuy Ho- C Chi nn dy trm tch tng dn t bc xung nam. Bin tin Flandrian vo Holocen gia lm mc nc bin dng cao cc i hnh thnh nn tp trm tch bt st bin ven- vng vnh ph bin trn ton b ng bng. Vo thi gian cui Holocen gia, bin li li ra khi khu vc ng bng.

- Thi k Holocen mun- Hin i: Phn ln din tch ng bng thot hn s khng ch ca ch bin. Hot ng ca sng dn ng vai tr thng tr, trm tch ca chng chia ct v lp y cc vng bin. Cc doi ct trm tch aQ23 to thnh cc b mt ni cao trn b mt ng bng, cc trm tch abQ23 ph lp cc a cc a hnh m lm cho b mt ng bng dn t trc din cn bng. Mt ct tng trm tch cng c quy lut cng sinh trong khng gian t trong lc a ra pha bin nh giai on trc. Cc doi ct bin c hnh thnh vo Holocen sm- gia b cc hot ng ca gi lm vun cao, ti to li v di chuyn to thnh cc di cn ct. Cc vng bin thi gian ny b thu hp v b m ly ho mnh. Trm tch bin to thnh di bi bin hin i phn b t nh sng triu cao tr ra ko di sut ng b pha ng ca trng. Hin nay, qu trnh pht trin ng bng Tuy Ha vn ang tip din di tc ng ca cc qu trnh a cht nhng chu tc ng mnh ca cc hot ng nhn sinh.

T nhng kt qu nghin cu trn c th rt ra mt s kt lun sau: (1) Lch s pht trin cc thnh to a cht ca G Sng Ba trong Kainozoi gm 3 giai on: Paleocen- Eocen, Oligocen- Miocen v Pliocen- t; (2) Lch s pht trin cc thnh to KZ phn nh tnh cht hot ng khng ng nht trong khng gian v theo thi gian ca G Sng Ba; (3) Trng Tuy Ha hnh thnh vo Pleistocen sm v chu nh hng chi phi r nt ca G Tuy Ha- C Chi trong t.

Chng 5- MI LIN QUAN CA KHONG SN VI CC THNH TO KAINOZOI I T GY SNG BA

Cc loi hnh khong sn lin quan n cc thnh to KZ trong phm vi G Sng Ba rt a dng v phong ph, bao gm 199 m khong (MK) v biu hin khong sn (BHKS) thuc nhiu nhm khong sn khc nhau.

5.1- c im a cht- khong sn 5.1.1- Nhin liu 5.1.1.1- Than bn: Than bn c thnh to trong t thung lng sng

ng bng v cc thung lng sng min ni b m ly ho hoc cc h pht trin trn ming ni la tt b m ly ha. Hin xc nh c 11 MK&BHKS c din phn b hp, quy m nh n rt nh.

5.1.1.2- Than nu: Lin quan n cc thnh to trm tch lc a tng m ly pht trin trn bi bi (ab) v h b m ly ho thuc cc HT Sng Ba (N12-3 sb), Bun Tu (N2 bt) v Kon Tum (N2 kt). Bao gm cc MK&BHKS: Ph Tc, Bun Thot, Ch S, Kon Tum v Bun Thu; u thuc loi cht lng thp.

5.1.2- Kim loi 5.1.2.1- Bauxit laterit: c hnh thnh trong v phong ho bazan HT Tc

Trng. Hin trn phm vi vng nghin cu mi xc nh c 3 MK&BHKS bauxit l p Kim Sn, Hn Lp v Sn nh; u thuc loi m nh.

5.1.2.2- Titan sa khong: Phn b dng sa khong ven bin, tp trung duy nht thnh mt BHKS ti khu vc Ninh Tnh, TP. Tuy Ho, quy m nh vi tr lng 20.000 tn ilmenit.

5.1.2.3- Vng sa khong: Phn b rng ri trong khu vc vi 27 im. Vng sa khong tp trung nhiu trong cc bc thm sng v lng sng hin i cc trng Kon Tum, Ayun Pa v Krng Pa. Cc MK&BHKS u c quy m nh v hu ht b khai thc t do nn t c gi tr cng nghip.

5.1.3- Nhm khng kim loi 5.1.3.1- Saphir sa khong: Phn b hn ch vi 3 MK&BHKS trong khu vc:

Sui Ci, sui T H v Quang Trung. Saphir sa khong phn b trong bi bi v lng sng Holocen mun ven ra trng Tuy Ho hoc trong y thm I tui Pleistocen mun k T; thng c quy m nh.

5.1.3.2- St kaolin: C 14 MK&BHKS, lin quan n nhiu phn v a tng c tui t Miocen gia- mun n hin i nhng tp trung ch yu vo trm tch sng HT Sng Ba v HT Bun Tu v HT Kon Tum. Thng c quy m nh n trung bnh, cht lng thp.

5.1.3.3- St iatomit: Cc thn qung c gi tr cng nghip phn b trong tp 2 HT Kon Tum (N2 kt) gm 12 MK&BHKS iatomit phn b trng Kon Tum. 2 BHKS st iatomit- trepen lin quan ti tp 2 HT Bun Tu (N2 bt). Cc m iatomit c quy m ln, cht lng trung bnh- km.

5.1.3.4- St bentonit: pht hin ti 23 MK&BHKS st bentonit, thuc 3 kiu ngun gc chnh: trm tch h, trm tch h cnh quan ni la, phong ho bazan; ngoi ra cn c kiu ngun gc hn hp.

a- St bentonit ngun gc h cnh quan ni la: Lin quan n tp 2 HT Bun Tu vi cc MK&BHKS l o Ch S, Sui Ea Yao, Cu Cy Sung (Ayun Pa), Bun Ma Thung (Krng Pa), Sui Bn, Cng Sn (Cng Sn) v vi tp 2 HT Kon Tum l Ho Bnh (Kon Tum). St bentonit ngun gc h cnh quan ni la c cht lng tt, tim nng tr lng ln.

b- St bentonit ngun gc h: Lin quan ngun gc h tp 2 HT Sng Ba (N12-3 sb) v h mng nga, h pht trin trn bi bi sng tui Holocen sm- gia. St bentonit thuc loi kim th, cht lng trung bnh- km, thu hi thp.

Ngoi ra, cn gp mt s BHKS ngun gc phong ho t phun tro bazan HT Tc Trng (N2-Q11 tt) Lng V v ngun gc hn hp im phun bn Ph Tc. St bentonit c mu xm xanh, xm pht xanh n xm vng dng bn nho.

5.1.4- Khong sn lm vt liu xy dng 5.1.4.1- St gch ngi: C ti 47 im phn b rng khp trong vng nghin

cu. Chng ch yu thuc tng st, bt st bi bi sng v h thuc nhiu tui khc nhau: N12-3 sb; N2 bt; N2 kt; apQ11-2; aQ12-3; aQ13; a,amQ21-2; a,abQ23; dpQ. Tuy nhin, c cht lng tt v quy m ln phn b trong cc thnh to amQ21-2 ( Tuy Ho); abQ23, aQ21-2 ( tt c cc trng).

5.1.4.2- Ct cui si xy dng: Tp trung ch yu trong cc trm tch lng v bi bi sng hin i (aQ23), t hn l trong cc thnh to aQ11-2; aQ12-3; aQ13; aQ21-2; dpQ. Chng phn b rng ri ti cc trng Tuy Ho, Krng Pa, Ayun Pa v Kon Tum vi 27 MK&BHKS khc nhau. Ct si dc theo dng sng Ba c tr lng rt ln, cht lng tt.

5.1.4.3- bazan xy dng: C lin quan ti bazan cc HT Tc Trng v Xun Lc vi 17 MK&BHKS pht hin. c cht lng tt, thng c quy m trung bnh.

5.1.4.4- Puzolan: Lin quan n v phong ho cc thnh to ni la v phun tro bazan KZ phn b quanh cc hng ni la tr HT Xun Lc hoc phong ho t bazan bt HT Tc Trng. Ngoi ra, cn c ngun puzolan lm ph gia xi mng c ly t iatomit, iatomit- trepen.

5.1.4.5- Laterit: xc nh c 3 MK&BHKS laterit l Plei Khol Bay, Ng Le v M Thnh hnh thnh trn v phong ho bazan HT Tc Trng trng Pleiku. Cc MK&BHKS laterit trong vng u c quy m nh.

5.2- Mi quan h ca khong sn vi cc thnh to Kainozoi Mi quan h gia cc loi hnh khong sn KZ trong khu vc G Sng Ba

vi cc yu t tng trm tch, a tng v a mo: 1- Than bn phn b trn cc m ly pht trin trn cc khc sng b ly ho,

cc h mng nga, h bi bi hoc cc h b m ly ho hnh thnh trn cc ming ni la m tt. Than bn lin quan n cc phn v a tng aQ13, abQ23, lQ.

2- Than nu c mi lin quan vi trm tch tng h- m ly pht trin trn bi bi thuc tp 2 HT Sng Ba (N12-3 sb) v trm tch tng h- m ly cnh quan ni la thuc tp 1 cc HT Bun Tu (N2 bt) v Kon Tum (N2 kt).

3- Titan sa khong c tch t trong cc di ct ven bin hin i thuc tng trm tch mQ23. Chng thng phn b bi bin chu tc ng ca sng v cc di cn ct thp chy st ng b hin i, ni c on a hnh b un cong.

4- Vng sa khong phn b trong trm tch ht th lt y cc bc thm sng c tui khc nhau trng Kon Tum v ra ty, ty nam trng Tuy Ho. C gi tr l thm sng bc II Kon Tum c tui Q12-3, lng sng sui hin i hoc trong trm tch dpQ.

5- Bauxit laterit l sn phm phong ho t bazan HT Tc Trng (N2-Q11 tt). Bauxit laterit thuc giai on to v Pleistocen sm- gia (Q11-2) pht trin cao a hnh 400-450m, ti khu vc c dc thoi 5-70.

6- Saphir sa khong phn b trong tng ht th lt y cc bc thm sng khc nhau. C tim nng ln trong tng lt y thm sng tui Q13.

7- St kaolin lin quan vi nhiu phn v a tng: N12-3 sb; N2 bt; N2 kt; aQ12-3; aQ21-2; dpQ. Thng phn b trong tp trm tch ht mn phn trn ca cc thnh to t, trong trm tch sng- h tp 2 HT Sng Ba (N12-3 sb) v trm tch h tp 3 cc HT Bun Tu (N2 bt) v Kon Tum (N2 kt).

8- St bentonit lin quan n nhiu phn v c tui t Neogen n t. Cc thn khong bentonit c gi tr ch yu lin quan n cc trm tch h cnh quan ni la tp 2 ca cc HT Bun Tu (N2 bt) v Kon Tum (N2 kt). St bentonit ngun gc trm tch sng v h trn bi bi ca HT Sng Ba (N12-3 sb) v trm tch Holocen sm- gia (aQ21-2) ch gp cc trng Krng Pa v Ayun Pa.

9- St iatomit phn b trong trm tch h ht mn tp 2 ca HT Kon Tum (N2 kt) v st iatomit- trepen phn b trong tp 2 ca HT Bun Tu (N2 bt).

10- St gch ngi lin quan n cc tng st- st bt tng bi bi (a), tng sng- m ly (ab), tng h lc a (l), tng hn hp sng- bin (am) thuc cc khong tui khc nhau, t Neogen n t. Cc phn v a tng t c gi tr l: aQ13; aQ21-2; a,apQ11-2; amQ21-2; abQ23. St gch ngi lin quan tp 2 HT Sng Ba (N12-3 sb), tp 1 ca cc HT Bun Tu (N2 bt) v Kon Tum (N2 kt).

11- Ct cui si xy dng ch yu lin quan n bi bi cao, bi bi thp v tng lng ca cc dng sng sui.

12- bazan xy dng c khai thc t cc lp bazan c st thuc tng dung nham ca cc HT Tc Trng v Xun Lc.

13- Puzolan lin quan n v phong ho bazan, hng ni la thuc cc HT Tc Trng (N2-Q11 tt) v Xun Lc (Q12 xl).

14- Laterit hnh thnh trn v phong ho bazan HT Tc Trng (N2-Q11 tt). Cc kiu v thun li cho vic hnh thnh laterit l Feralit v Ferit; ti khu vc a hnh g i c dc khng qu 5-70 v chu tc ng ca nc ngm.

T cc kt qu phn tch, nh gi trn c th cho thy: (1) Khu vc G Sng Ba c ngun ti nguyn khong sn lin quan n cc thnh to KZ rt a dng v loi hnh s dng, phm vi phn b rng ri. Nhiu loi hnh khong sn c tim nng ln v gi tr s dng rng ri trong nn kinh t quc dn nh st iatomit, st bentonit, st gch ngi, ct cui si v xy dng; (2) Mi loi hnh khong sn u

c v tr a tng, c im tng trm tch, c im a hnh- a mo ca cc thnh to KZ G Sng Ba.

KT LUN V KIN NGH Kt lun T nhng kt qu nghin cu trn, c th rt ra mt s kt lun nh sau: 1- a tng KZ G Sng Ba bao gm 23 phn v c tui t Miocen gia n

hin i. Phn v a tng KZ c tui c nht l HT Sng Ba c tui Miocen gia- mun (N12-3 sb).

2- H tng Bun Tu (N2 bt) c tui Pliocen phn b cc trng Krng Pa v Ayun Pa l HT ln u tin c xc lp p ng y cc tiu ch ca thang a tng a phng theo Quy phm a tng Vit Nam nm 1994.

3- Trm tch KZ lp y cc trng tch bit hnh thnh v pht trin dc G Sng Ba c ngun gc v iu kin thnh to khc nhau. Trm tch lc a Miocen gia- mun phn b trong cc bn trng Ayun Pa v Krng Pa. Trm tch lc a- phun tro Pliocen phn b cc trng Kon Tum, Pleiku, Ayun Pa v Krng Pa. Cc trm tch phun tro bazan tui Pliocen- t phn b ch yu trong cc trng Kon Tum, Pleiku v cao nguyn Vn Ho. Trm tch t ngun gc lc a phn b trong cc trng lc a cn trm tch ngun gc lc a- bin ch phn b trng Tuy Ha.

4- Lch s pht trin cc thnh to KZ din ra trong ba giai on: Paleocen- Eocen, Oligocen- Miocen v Pliocen- t.

Giai on Paleocen- Eocen c trng bi cc qu trnh xm thc bc mn mnh m trn nn hot ng magma xm nhp hot ng tch cc.

Giai on Oligocen- Miocen c trng bi cc qu trnh xm thc bc mn v tch t trm tch din ra trn nn hot ng magma ngng ngh. Giai on Oligocen- Miocen bao gm 2 ph giai on vi cc c trng l s chuyn tip t qu trnh bc mn xm thc thng tr trong ph giai on Oligocen- Miocen sm sang qu trnh tch t trm tch lc a cha than trong cc bn trng Ayun Pa v Krng Pa lin quan ti hot ng ca G Sng Ba trong ph giai on Miocen gia- mun.

Giai on Pliocen- t c trng bi s hnh thnh cc bn tch t trm tch Pleiku, Kon Tum pha bc G v m rng bn tch t cc trng Ayun Pa, Krng Pa trong iu kin hot ng phun tro bazan mnh m. Giai on Pliocen- t bao gm 2 ph giai on: Pliocen- Pleistocen sm v Pleistocen sm- Holocen.

5- Lch s pht trin cc thnh to KZ phn nh tnh cht khng ng nht trong khng gian v theo thi gian ca hot ng Tn kin to khu vc. Cc trng Krng Pa, Ayun Pa, Pleiku v Kon Tum lin quan cht ch vi hot ng ca G Sng Ba, c xu hng hot ng tng dn t pha nam ln pha bc. Mc v tnh cht hot ng ca G Sng Ba to nn tnh a dng v ngun gc, thnh phn

v iu kin hnh thnh ca cc thnh to KZ trong vng nghin cu. Trng Tuy Ha c hnh thnh vo Pleistocen sm v chu nh hng chi phi r nt bi hot ng ca G Tuy Ha- C Chi trong t.

6- Khu vc G Sng Ba c ngun ti nguyn khong sn lin quan n cc thnh to KZ a dng v loi hnh s dng, c tim nng ln vi 199 MK&BHKS cc loi, phm vi phn b rng ri. Nhiu loi hnh khong sn c tim nng ln v gi tr s dng rng ri trong nn kinh t quc dn nh st iatomit, st bentonit, st gch ngi, ct cui si v xy dng. Mi loi hnh khong sn c v tr a tng, c im tng trm tch v c im a hnh- a mo lin quan cht ch vi cc thnh to KZ G Sng Ba.

Kin ngh 1- Trm tch Neogen trong khu vc ch yu l thnh phn vn th ngho di

tch c sinh nn vic nh tui v lin h a tng cn gp nhiu kh khn. Cc kt qu phn tch tui tuyt i ca bazan thu thp c u cha xc nh c chnh xc v tr a tng nn ch c gi tr tham kho. Do , phn chia v lin h a tng c chnh xc v chi tit hn th cn thit b xung thm cng tc phn tch tui tuyt i; c bit l cc mu bazan xen kp trong trm tch Neogen thu thp c qua cc l khoan.

2- Mi quan h a tng gia HT Sng Ba v cc HT Bun Tu v HT Kon Tum vn cha c xc lp chnh xc trn thc a. Do , cn quan tm tm kim tip tc trong qu trnh o v chi tit sau ny hoc s dng phng php a chn phn x phn gii cao kt hp vi phn tch chi tit cc l khoan i km.

3- Cho n nay, trn phm vi cc bn trng lc a Nam Trung b ni chung v G Sng Ba ni ring vn cha xc nh c s c mt ca trm tch trc Miocen gia trong khi cc bn trng trn thm lc a k cn khng nh c s c mt ca cc trm tch Eocen, Oligocen v Miocen sm. Cn c nhng nghin cu chi tit hn c th khng nh c hay khng c trm tch trc Miocen gia khu vc Nam Trung b.

4- xc lp li c ch thnh to trng Tuy Ha cn c nhng nghin cu chi tit hn v G Tuy Ha- C Chi v mi quan h ca chng vi G Sng Ba trong t.

CC CNG TRNH CNG B LIN QUAN N LUN N

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2. L Th Nghinh, Petrova V.V., Phan ng Pha, Nguyn Trng Ym, o Th Min (1996), Vi nt v khong ho zeolit trong cc thnh to phun tro Pliocen vng cao nguyn Vn Ho, a cht Ti nguyn, tp II, tr.214-222, Nxb KH&KT, H Ni.

3. a . B., . (1997). , a, (2), c. 163-174, .

4. o Th Min, Phan ng Pha, L Th Nghinh (1998), Diatomeae Neogen vi s thnh to cc khong sn lin quan trn cao nguyn Vn Ho, Tp ch Cc KH v T, 20(2), tr.115-122, H Ni.

5. o Th Min, Phan ng Pha, L Th Nghinh (1999), c im ca Diatomeae Ty Nguyn, Tp ch a cht, (252), tr. 1-7, H Ni.

6. L Th Nghinh, Nguyn Ngc, Phan ng Pha, Nguyn Trng Ym (2001), Vi nt v lch s pht trin ng bng Tuy Ho trong Pleistocen gia (?)- mun- Holocen, Tp ch Cc KH v T, 23(4), tr.329-336, H Ni.

7. L Th Nghinh, o Th Min, Phan ng Pha, Trn Th Su, Nguyn Thu Cc (2004), c im v iu kin thnh to Diatomit Nam Vit Nam, Tp ch Cc KH v T, 26(4), tr.493-502, H Ni.

8. Phan ng Pha, L Th Nghinh (2006), Cc kiu ngun gc bentonit Ty Nguyn, K yu Hi ngh Khoa hc k nim 40 nm Khoa a cht Trng HKHTN (HQGHN), thng 10/2006, tr.88-102, H Ni.

9. Phan ng Pha, L Th Nghinh, Kiu Qu Nam, Nguyn Xun Huyn (2007), c im phn b v iu kin tch t cc thnh to st bentonit v iatomit khu vc Cheo Reo, Ph Tc v cao nguyn Vn Ho, Tp ch a cht, (299), tr.50-59, H Ni.

10. Nguyn ch D, Phan ng Pha v nnk (2010), a tng Kainozoi ti cc ng bng ven bin Nam Trung b Vit Nam, Tp ch Cc KH v T, 32(1), tr. 1-7, H Ni.

Trm tch sng (a,apQ11-2) phn b ven ra cc trng Krng