Dgc diem cdu true dja chdt khu vac be lu Chinh -|
Vung Mdy dya tren ket qud minh gidi tdi lidu dja chdi
ThS. L« Dflc Cdng, PGS.TS. Nguyin Trong Tin, TS. Trjnh Xudn Cu^
K5. Nguyin H&u Quynh, CN. NguyAn Olng Hoing Vt^n Ddu khi Viit Nam
Tdm tSt . Khu vuc bi TU Chinh - Vung Mdy Id khu vUc nUdc sdu xa bd, cd diin tich khodng ISO.OOOkm". Hogt ddng 0m ktii
thdm dd ddu khi d khu vUc ndy trong nhi^g ndm gdn ddy dd dUtfc quan tdm vd cd thim cdc khdo sdt dia chdn dm nhu nghiin cdu vi dia chdt vd tiim ndng khodng sdn, dde blit Id tUm ndng ddu khi. Dde dlim cdu trdc dia chdt ldn vuc biTuChinh - Vung Mdy vd ldn edn rdt phifc tgp, chUa duge tdm sdng td. Ngodi ra, dd sdu mUc nUdc biin trong kt\^
vuc thay ddi tifvdi chuc mit tgi cdc bdi ngdm din vdi trdm mit vd sdu han tit 1.000 - 2.800m edng inh hudng ldn d6, edng tdc khdo sdt vd nghiin cCfu. Trong khu vUc ndy chl cd mdt giing khoan PV-94-2X trin khdi ndng Tu Chinh dd liin sdng td mdt phdn vi edu triic dja chdt, nhUng nhin chung chUa du casddiddnh gid vi dia chdt vd tiim ndng khoing sdn cua cd khu vUc. Trong bdi vHt ndy, cdc tdc gid phdn tich dde diim cdu true dia chdt ciia khu vUc biTUChlnh - Vung Mdy dUa trin ede kit qud minh gidi tdi lieu dja chdn 2D din thdi dUm hiin tgL
Kit qud minh gidi tdi Iiiu dja chdn 2D cho todn bd khu vUc bi Tu Chinh - Vung Mdy thi hiin qua cdc bdn dd eSv true dugc thdnh lap mc^bao gdm: bdn dd ndc mdng trUde Di tam, Ollgocen, Miocen dUdi, Miocen giUa vd Miocen trin.
Bdn do hi thdng ddft gdy khu vUc nghiin cUu dd duge thdnh lap, trong dd cdc hi thdng ddt gdy chinh gdm: hi thing Ddng Bdc - Tdy Nam, hi thong d kinh tuyin vd hi thong d vf tuyen. Trin casd nghiin cdfu, phdn Uch cdu trdcdjadidl.
cdc tdc gid da phdn chia khu vUc Tu Chinh - Vdng Mdy thdnh 6 dan vi cdu true ehinh Id: ddi Ddng Bdc BiNam Cdn Sod ddi gidn ddy Biin Ddng; ddi ndng Tu Chinh - Phue Nguyen - Phuc Tdn; trung Vung Mdy; ddi ndng DdLdt-DdTdy;dd ndng Vung Mdy - An Bang.
M d d a u
Be Tfl Chinh - Vung May la be tram tich nfldc siu xa bd trong dd dao g i n d i t lien nhat I I Trfldng Sa cich vjnh Cam Ranh 450km, d i o Phfl Qu^ 400km, khu vflc nghidn cflu cd dien tfch rdng khoing 150.000km' vdi vj tri dja ly: tfl 6"15'- lOoiO'vTdpBlcva 109^15'- lU^SS'kinh dd Ddng gdm dien tfch d e Ld 130 - 136, Ld 155 - 160 v l Ld 180 - 185. Mflc nfldc b i i n khu vyc nghien cflu thay ddi t f l v i i chuc met tai d c b l i ngam den hang tram mdt v l siu hon d i n 3.000m. Trong do p h i n Idn didn tich d c Ld 133,134, phan Tay Bic Ld 135, phfa Tiy Ld 157 v l gdc Tay Ble Lo 158 ed mflc nflde bien ndng hon {dfldi 1.000m) tdn tai eic bai da n g i m , bai can nhflVung Miy, Huyen Trin, Que Dfldng, Phuc Nguyen va Tfl Chfnh, mot so d i o n h f l D i Tiy, Trfldng Sa... Cic dao v l bai n g i m da sd la d i o do san hd p h i t t r i l n tren d c khdi nhd cao, hoac tren d c khdi nfli Ifla t h o l i hda.
Cdng t i c nghien cflu dia chat - i^a vat ly tai khu vflc Tfl Chfnh - Vung M i y b i t dau t f l nhflng n i m 70 efla t h l ky XX.
Cho d i n nay, edng t i e nghien cflru tim k i l m thim do dit khi d l dflpe khio sit vdi mang Ifldi khio sit dja chlni dflpc phfl vdi mflc dp t f l khu vyc d i n chi t i l t tai mdt s6 M phia Tiy, Tay Nam vdi khoing hon 30.000km tuyin (Hinh
Cie nghien cflu d i e d i l m dja c h i t cua khu vflc naydi tren d c t i i l i l u k h i o sit dja chan dflpc thyc hien tflna 1993. Nhflng hoat ddng nghien cflu v i n edn nhilu hand n h i t l i khi hien nay khu vyc nghidn cflu dflpc md rdng^
gom mdt phan q u i n d i o Tradng Sa.Tnang bai vilt n g i i gidi thieu k i t q u i nghidn cflu d i n h g l l die d i ^ trfle dja c h i t dfla t r i n k i t q u i minh g i l i t i i lidn dja ch|
thdi d i l m hi^n tai [1,4,5,7,19,20].
1. Minh g i i i t i i li&u dja chan
Tren them lyc dja Vidt Nam, khu vflc be Tfl f Vung May l i vflng bien nfldc siu, chaa ed nhilu e l d tin eung nha k i t q u i nghien cflu v l ^ a e h l t T r o r ^ vflc chi cd mpt g i l n g khoan duy nhat PV-94-2X vdi chi*
24 I-505/2012
PETROVIETNAM
Hmh 1 So 1o tuven khdo sot dia t Ao/i khu vuc nghu
^
s.iu 3 331m tren khdi nhd eao Tfl Chinh. Viee lien ket cac ranh gidi dja chin efla b l tic gii sfl dung tai heu gieng khoan niy va dja ting mdt sd gilng khoan d khu vuc phin phfa Ddng cfla b l Nam Cdn Son (Hinh 2), Tfl ci'ic tuyin lidn kit chuin di qua cAc gieng khoan tac g i i d l lidn kit cho toin bd t i l lidu dia chan khu vuc Tu Chfnh-Vung Miy vdi ele ranh gioi dia chan chuan dflpc dmh nghTa v l xic dinh tu' cac gieng khoan v l dac trflng trfldng sdng, tinh luong dong ve mdi trfldng trim tfeh, thdi gian thinh tao (Hinh 3). Ket qui thinh lap bd bin do d u trflc cua cac tang chuan gdm: nde mdng trfldc Dd tam, ndc Oligoccn, ndc Miocen dfldi, ndc Miocen gifla, noc Miocen.
2. Ba n do cau true va he thdng dflt gay Cic bin dd elu true khu vye be Tfl Chinh - Vung May ty le 1:200.000 da dflpc thanh lap dfla tren eO sd lien kit minh gili t i i lidu dia chan 2D da cd den thdi dilm hien tai.
Hinh 2. Cdr dia tang tong hap va cac Ti
Hinh 3. Mat dia chdn ciing vdi cdc tdng minh gidi cda khu vUC nghiin cdU
Oe nghidn cflu die diem eau true cfla khu vfle, cae ban dd eau true dddc sfl dyng.
Tuy nhien trong pham vi bai Viet nay, cac tic gii sfl dyng ehu yeu ban do eau true nde mdng trfldc De tam, bin do t h l hidn dape khung d u trfle v l kiln tao: ndc mdng trade De tam la mdt bit chinh hpp khu vyc Idn, sdng phin xa ed bien dp manh, dd lien tuc tdt, ben dadi nd la d c phin xa tring hole hdn ddn, ddi cho la d c phan xa phan Idp cfla d c thinh tao trfldc De tam de theo ddi tren d c mat cat d j a c h l n d d e khu vflc trung siu hole cac dja hlo, bin dja hlo (Hinh 4). Phia dfldi cac khdi carbonate, trung tam ele trung siu sdng phin xa y •-': •>'• diy m i t phin xa
25 i i
t h l hi§n rd d u trflc eua mdng trfldc Kamozol vdi d$ siu thay ddi Idn tfl khoing hon 2.000m d eic khdi nhd nhflTfl Chlnh -Vung Miy, d e kh6l nhd eao d khu vyc phfa Tiy v l Ddng khu vye nghidn cflu d i n khoing hon 10.000m d d c trung s i u thudc p h i n phia Tiy, Tiy Ble v l p h i n trung t l m , p h i n phfa Ddng khu vyc nghidn eflu. Tuy nhidn, dd siu myc nfldc b i i n thay ddi tflong ddi Idn tfl v i i chye mdt d i n h I n g nghin mdt [1,4,5,7,9].
Trdn b i n dd elu trOc cfla m | t mdng niy, chflng ta t h i y tdn tai d e h i thdng dflt gay ehinh efla khu vye n g h i i n cflu. Cie hd thdng 6dX g i y quan s i t qua d e mat d t dja c h i n t h i y p h i t t r i l n tfl trfldc Eoeen (?) - Ollgocen d i n h i t Miocen gifla, cd quy md p h i t t r i l n khic nhau e l v l ehilu d l i eflng nhfl b i i n dd djeh ehuyin [10,11, 13,15]. Chilu d l i cfla d c hd thdng dflt gay p h i n ldn v i i chuc km, mdt sd dflt gay p h i t t r i l n kdo d l i d i n h I n g tram km. Ket hpp d e k^t q u i minh g i l i d u trflc v l d c tai lieu dj thfldng tfl, dj thfldng trong Ifle (Hinh 5) dya v i o phflong p h i t t r i l n , bien dp dieh chuyin, mflc dd p h i huy, thdi gian hinh t h i n h v l hoat ddng cua cie dflt gay, chung ta cd the n h i n t h i y khu vye nghidn cflu tdn tai 4 he thdng dflt gay: (1) He thdng dflt g i y phflong Ddng Ble - Tay Nam, (2) H I thdng dflt gay phflOng i kinh tuyen, (3) He thdng dflt gay phflOng i vT t u y i n v i (4) He thdng dflt gay phaong Tay Bic - Ddng Nam dapc md t l chi tiet nhfl sau:
Hinh 4. Bdn do cdu true mat ndc mdng trUdc Kainozoi khu vUc nghiin cUU I 26 DiblUri-80 5/2012
Chflng p h i t t r i l n rdng k h i p trdn khu vflc nghidn cflu, hoat ddng msinh trong thdi gian Ollgocen v i Miocen dfldi, sau dd t i l ho?t ddng v i o Miocen gifla rdi g i i m d i n cfldng dd ho^t ddng v i ngflng v i o cudi Miocen mudn. D i y I I h$
thdng dflt g i y chinh khdng c h l hinh t h l i d u trflc chung cfla t o i n khu vye, h l u h i t l i c&c dflt g i y t h u | n dflpc hinh t h i n h v i p h i t t r i l n do trfldng flfng suit t i c h d i n theo hfldng Tiy Ble - Ddng Nam (vudng gdc vdi true md rdng b i i n Ddng) v i o thdi ky Eoeen (7) - Oligocen. Cfldng d$ ho^t ddng cfla hd thdng cic dflt g i y n i y r i t manh, tao nin cic dia h l o , b i n dja h i o v i d c dja Ifly, b i n dia luy xen ke nhau.
Cd dflt g i y d l i h i n g t r i m km v l bidn dd djch chuyin t6I 1.500 - 2.000m d khu vyc Vung Miy, mdt sd noi hoat ddng eua ele dflt g i y n i y kdm theo phun t r i o magma.
Hi thing dCft gdy phuang d kinh tuyin: Phit triln chfl y i u d p h i n Tiy Nam trong vung n i n g Tfl Chinh-Vung M i y v l p h i n phia Ddng khu vyc nghidn eflu. Chflng la cic dflt gay t h u i n , hoat ddng theo co c h l c i n g g i l n , ed biin dd Idn d t i n g mdng, Ollgocen v i g i i m d i n len d e tang t r i n . Chinh d c dut g i y n i y d l l i m chuyin dich d c did g i y dflpc hinh t h i n h tfltrflde, ddng thdi l i m thay ddi hinh t h l i elu trfle eua bdn thfl d p Oligocen is mdt sd n d , d k bidt d p h i n phfa Bic khu vac nghidn cflu. He thdng diJt g i y I kinh t u y i n hinh t h i n h mudn hon so vdi hd thong dflt gay Ddng Ble - Tiy Nam. Chung dflpc hinh thinh vio cudi giai doan tao rift sdm (Oligocen) d i u giai doan tao rift mudn (Miocen dfldi) v i t i l p tuc hoat ddng trong suit Miocen gifl^ - mudn, mdt s6 dut gay kdo dli mudn hon d i n Pliocen.
Hi thdng diit gdy phuung d vi tuyin: Phin bd chfl y i u d p h i n Ddng Nam khu vflc nghien cflu thudc phia Ble ddi tnjng Tay Vung Miy, ptiln g i i ^ ddi n i n g Vflng M i y - Trfldng Sa. D i y II cac dflt g i y t h u i n , dflpe hinh t h i n h trddc giai doan tao rift v l p h i t t r i l n kdo d i i den h i t giai doan dong tao rift. Quy md p h i t t r i l n eua hd thfing dflt g i y n i y khdng Idn, chflng khdng ddng vai trd q u y i t dinh d i n hinh t h l i d u trflc chung ciia kiw vflc nghien cflU m i chi l i m phflc tap them v l mSt d u tnjc efla mdt sd don vj d u tnjc trong khu vifc Hi th6ng ddlt gdy phuang Tdy Bdc - OAnS Nam: H | thdng dflt g i y n i y p h i t t r i l n chu y^u ve phia Ddng Nam khu vyc nghidn cflu, chOaj hinh t h i n h do sfl p h i t t r i l n xoay efla h i th6^
dflt gay i kinh t u y i n do lyc hflt cfla khdi sut Ifln cua b l Natuna, chflng phan chia d c ciu
PETROVIETNAM
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Hinh 5. Ban dddi thuong K/iaivo trong luc (bj ve (inh khu vUc nghiei true 6 khu vUc nay co liuonq Tay
Bac - Dong Nam
3. Dac diem dja chat va phan vung cau true khu vUc Ta Chinh - Vung May
Be Tu Chinh - Vung May nam trong khu vUc cd cac yeu to cau - kien tao het sfle phflc tap hinh thanh tren mien cau true lyc dia sot do qua trinh dai duong hoa bien Dong (Hinh 6).
Do qua tnnh van dong kien tao, sU tuong tac cua cac mang tren them Sunda da hinh thanh mot loat be tram tich kieu rift sau cung vao cuoi Mesozoi (?) dau Kainozoi nhu cac be vinh Thai Lan, Malaysia, Dong va Tay Natuna, Sarawak, Brunei, Sabah va d e b l d Nam Viet Nam trong dd cd
be Tfl Chinh - Vung Miy. Cic b l tram tfch nay dddc hinh thinh, phit trien ehfl yeu tren miln vd lue dja hoac vd lye dja ehuyin tiep. Bien Ddng, dflpc hinh thinh do qua trinh tich dan tao vd dai dflOng tfl Oligocen trd lai day, nefi Idp vd trii dit cd chieu day khoing 5 - 8km. Cac d u true cfla vd lyc ^ a bj dai dflOng hda va hinh thinh biin Ddng vdi phia Bac II d u true Hoang Sa - Maclesfield v i phia Nam la d u true Trfldng Sa Reed Bank, vd lue dja d diy b| vat mdng dao ddng tfl 8 - 20km [8,12,14].
Tren bin do elu trfle nde mdng am hpc khu vyc them lye cfiaDdng Nam Viet Nam va vflng lan cin cho thay vung
Hinh 6. Khu vUc be Tu Chlnh • Vung Mdy trong phdng chung kiin tao khu vUc
Td Chfnh - Vflng May nim mdt phin d ranh gidi ngoli cflng thim lye dia v l mdt phin nim d be ngoai [15].Them lue dia Ddng Nam Viet Nam gom d c yiu to d u - kien tao chinh nhfl: b l Phfl KhInh, be Cflu Long, be Nam Cdn Son, miln lue dja sdt trdi trflpt, hfly hoai Trfldng Sa v l miln vd dai dflong. & phin nude sau tfl tren 1.000m gdm trung Vung Miy, ddi ning Vung Miy - Da Lit phit triln trdn vd chuyen tiep va be nfldc siu bien Ddng phit trien tren vd dai dflong (Hinh 6).
Khu vfle be Tfl Chfnh - Vung May gdm d c ddi ning v l d c trung nam xen ke, phat triln chfl yiu thpo hadng
Ddng Bic -Tiy Nam. Ddi n i n g cd d^ng khdi - dja luy ho|c khdi dflt g i y cd Idp phu t r i m tich Kainozoi d i y k h o i n g 2,5 - 3,5km, Cic trung cd d?ng dja hio, b i n dja h i o dflpe l i p d i y bdi t r i m tich Kainozoi vdi b l d i y d^t tdi 6 - 8km.
Dya trdn d c d|c d i l m v l elu trflc, h$ thdng dflt giy, d i e d i l m v l t r i m tieh v l q u i trinh p h i t t r i l n dja chit, ehung ta cd t h l p h i n chia khu vyc nghidn cflu ra eic dOn vj d u trflc sau (Hinh 7) [1,2,3,4,5,6].
3.1. OdI Ddng Bdc biNam Cdn San
Ddi Ddng Bic b l Nam Cdn San I I p h i n t i l p tyc efla b l Nam Cdn Son v l phia Ddng Bic, cd hfldng d u trflc g i n nhfl Ble - Ddng Ble, Tiy • Tiy Nam. Ddi d u t h i n h bdi d c ddi nang, ddi trung hep kdo d l i , b l d i y t r i m tich Kainozoi dat tdi 7.000m. VI viy, tai d i y chi quan sit t h i y mdt v l l d u tao p h i t t r i l n k l thfla t r i n dia luy cfla thdi ky Synrift vdi chilu siu tdi dinh d u tao k h i Idn (4.200 - 4.500m). M i t dd dflt g i y eua ddi n i y tflong ddi d i y ehflng td ddi n i y bi I n h hadng manh bdi k i l n tao t i c h g i i n b i i n Ddng k i t thflc v i o trfldc Miocen gifla. Ddi n i y cd t h l dflpc chia t h i n h hai phu ddi gdm:
Phu cdc ddi ndng chiim p h i n Idn didn tieh d phfa Tiy eic Ld 129 - 1 3 1 . Phy ddi nay dflpc phfl bdi eic t r i m tich Kainozoi day t f l 2.000m den tren 6.000m, gdm cic khdi nhd v l ngan cIch gifla eic khdi nhd l i d c trung nhd hep, trong phu ddi n i y d c dut gay phat t r i l n ehu y i u theo
Hinh 7. Cdc yiu tdcdu true chfnh khu vuc nghiin a
hfldng Ddng Ble - Tiy Nam v i khdng c h l hinh t h l i ci khdi nhd v i d c trflng nhd h^p.
P/iy cdc ddi trung thudc ph^im vl phfa Tiy d c Ld 13' 132 gdm d c dja h l o , b i n dja h i o nhd p h i t t r i l n the hfldng Tiy Ble - Ddng Nam trung vdi phflong cfla ele dt giy. Trim tfch cfla phy ddi n i y tflPng ddi Idn, ehd siu nha d?t t r i n 9.000m, ndng n h i t 2.500 - 3.500m, bao gdm cli t h i n h tao t f l Oligocen d i n Pliocen 0 $ tfl.
3.2. Ddi gidn ddy biin Ddng
Ddi g i l n d i y b l l n Ddng cdn goi I I trung siu bl^r Ddng d khu vyc Tfl Chinh - Vung M i y l i p h i n klo dli v^
phia Tiy Nam cfla vung t i c h g i l n d i y b i i n Ddng, dd S3L nflde b i i n t f l 2.000 • 4.000m. D i y l i vflng vd lye dia bj vll mdng so vdi d c don vi d u tao k l bdn. B l d i y trim tich Kainozoi, d|e bidt t r i m tieh Neogen r i t mdng, khoing 800 - 1.000m phu k l I p Idn t r i m tieh c6 hPn v l 2 phfa ranh gidi cfla ddi. B l m i t d i y b i i n tflong ddi b i n g phiiKi, khdng quan s i t t h i y hoat ddng nui Ifla. Cic dflt giy chu y i u ed hadng Ddng Ble - Tiy Nam, ridng dflt giy phia Nam ed hfldng I vT t u y i n vdi bidn dd djch chuyen khi ldn.
khoing 700 - 800m.
3.3. Ddi ndng Tu Chlnh - Phdc Nguyen - Phuc Tdn Ddi n i n g tnang pham vi cic Ld 132 -134 v l mot phSn nhd d e Ld 155, 156 vdi dd s i u nfldc b i i n thay ddi tfl vai chuc mdt d i n mdt nghin mdt. T i l p g i l p v l phfa TBy Nam eua ddi l i b l Nam Cdn Son, v l phia Ddng li tnJng Vflng Miy, cdn v l phia Ble I I ddi gian diy b i ^ Ddng. Trong d c v i n lidu nghiin cufu tnidc day, toJn bp didn tich eua ddi n i y dflpc gpi l i 'ddi ning ria'[4, 15]. Ciu trfle ddi n i n g phflc tap, cd dang khdi phin dx bdi n h i l u dflt g i y chfl y i u theo hfldng €)dng Ble -TSy Nam v l tdn t^i nhilu d u tao dang dja luy. Mdt sd cau tao d?ng khdi p h i t t r i l n d i n t | n d i y bien m l phfl trin chflng l i eic t h i n h tao carbonate, p h i n ldn la am t i ^ san hd. d p h i n ria Ddng cfla ddi, mot sd noi ed mat hoat ddng nfli Ifli eua d c giai doan khic nhau. ^ Trong pham vi ddi n i y ed n h i l u ddi ning dja phaong da dapc dat ten nha n i n g Tfl Chinh, ning Phflc Nguyen, n i n g Phflc Tan, n i n g Huyin Tran vJ ele trung Bic Tfl Chinh, €>dng Tfl Chinh v i Tiy Phiic Nguydn...
3.4. Trung Vung Mdy
Trung Vung May I I trung ldn n i m trong mflt p h i n efla d c Ld 157 -160, dp s i u nfldc b i i n thay dfi
28 DlUKHi-Sd 5/2012
PETROVIETNAM
tfl 200 - 2.000m.Trlm tich Kainozoi trong ddi n i y ed b l d i y k h i Idn, dat tdi hon 7.000m. He thong dflt gay trong trung Vung M i y ed hfldng Ddng Ble -Tiy Nam, phd bien I I d c dflt gay cd hfldng I vT t u y i n , mdt sd dflt gay cd hfldng Tiy Bae - Ddng Nam phan bd d phfa Nam eCia trung, Cic dflt gay lam phflc tap dia hinh thanh d e vi dja luy, dja h l o v l ban dja h i o . Cae d u tao p h i t trien k l thfla trdn d c vi dja luy deu cd d i l u kien thuan Ipi ve trien vpng d i u khi, die biet d c d u tao ke d c dia h l o hinh t h i n h trong giai do?n ddng t r i m tfeh. Hoat ddng dflt gay trong pham vi cua ddi deu k i t thflc vao trade Miocen gifla, t r i m tich Pliocen - Dd t f l it bi b l l n dj v l gan nhfl p h i n bd n i m ngang. V l phia Tiy eua ddi d mdt sd noi quan sit t h i y hoat ddng nfli Ifla trdn mat d t dja chan.
3.5. Ddi ndng Dd Ldt - Dd Tdy
Ddi n i y n i m d phfa Ddng khu vflc nghien eflu, cd cau true bj phan dj manh trong Oligocen d i e biet trong Oligocen sdm, d e khdi n i n g v l hd sut n i m xen ke nhau, d c hd syt dflpc lap day ehu yeu trong giai doan Oligocen, vdi chieu day tram tich thay ddi dang ke, chd day nhat dat den 5.000m, eho mdng nhat chi khoing 2.000m, nhit la trdn cic ddi ning.
Dac diem phat t r i l n cfla ddi nay chu y i u theo hfldng Ddng Ble -Tay Nam va chju anh hfldng manh cfla q u i trinh t i c h gian Bien Ddng nen he thdng dut gay Ddng Bac-Tly Namgan nhfl song song vdi true tach g i l n . D i y la ddi cd d e hoat ddng tan kien tao manh me nhat trong khu vflc n i y d i e biet I I d c boat ddng nui Ifla t r i vao thcri k)r cudi Miocen d i u Pliocen. Nhflng hoat ddng n i y da lam pha vd d c elu true da dflpc hinh thanh trfldc dd, lam eho d u true d khu vflc nay da phflc tap lai c i n g phflc tap hcxn.
3.6. Did ndng Vung Mdy -An Bang
N i m d phfa Ddng Nam, phia Tay g i l p vdi trung Vflng May, phfa Ble giap ddi n i n g Da L i t - D l Tiy, phia Ddng ndi tiep vdi q u i n d i o Trfldng Sa. Ddi n i n g Vung M i y - A n Bang la mdt ddi nang tflOng ddi dn djnh dflpc cau t h i n h tfl cac khdi nang nam xen ke nhau va p h i t t r i l n theo hfldng Ddng Bic - TSy Nam. Chieu day t r i m tfeh Kainozoi d ddi nay tflong ddi mdng, d c thanh tao ehfl y i u I I Oligocen, Miocen va Pliocen Oe tfl. Cic dflt gay trong ddi n i y ehfl y i u la d e he thdng dut gay Ddng Ble - Tay Nam, Ddng - Tiy v i a kinh tuyen. Day ehfl yeu l a d e dflt gay tre da dflpe hinh thanh ehu yeu trong thdi ky tach gian bien Ddng ed le vao eudi Oligocen, mpt so dflt gay co t i i hoat dpng lai sau niy. Trong ddi n i y tdn tai mdt s6 n i n g dia phflong
nhfl n i n g Vung May, n i n g Trfldng Sa.., Tai ddi niy quan s i t t h i y b i i u hien nhilu nui Ifla, cd the dfloc hinh t h i n h trong Pliocen - Dd tfl.
Vi§c p h i n vflng d u trfle kiln t?o n h l m muc dfch p h i n chia khu vfle nghiin eflu t h i n h d c don vi d u trflc khic nhau. Mdi don vj d u trflc cd d i e d i l m d u true, k i l n tao, CO c h l hinh t h i n h v i Ijch sfl p h i t t r i l n dja c h i t tflong ddi ddng n h i t . Ranh gidi gifla chung dflpc Ifla chon trflng vdi cic dflt gay ed quy md tflong ddi Idn hole cic y i u td d u trflc d i e biet nhfl d e ehu6i nui Ifla. Trong cic dan vj d u true, tuy theo die d i l m elu trflc k i l n tao lai cd t h l dflpc p h i n chia t h i n h d c y i u td d u trfle nhd hOn ed d e die trflng tflOng ddi ddng nhit. Vi^e Ifla chpn, p h i n ehia cic don vj v l yeu td elu true mdt d c h hop ly se cung c l p mpt cii nhin khich quan v l ehinh xle ddi vdi q u i trinh hinh t h i n h , phat t r i l n cic y i u td elu true eua khu vyc.
Tfl dd, chung ta ed djnh hfldng eho cic cdng t i c nghien eflu t i l p theo dac bi^t 11 cdng tac tlm kiem tham dd va khai t h i c dau khi, khi hydrate. Qua d c nghidn cflu niy, chflng ta nhan thay bflc tranh tdng q u i t ve khu vyc Tfl Chinh - Vung May cd dac d i l m dia c h i t r i t phflc tap v l bi chi phdi I n h hfldng eua nhieu t i e nhan k i l n tao trong khu vye nhfl tach gian Blln Ddng, hut ehlm Natuna... dflpe the hien qua cic he thdng dflt gay, phan bd d u true.
Ket luan
Tren cO sd tong hpp va cap nhit k i t q u i minh g i l i t i i lieu dja chan 2D, p h i n tfeh va danh gia tong hpp eic tai lieu i^a chit, dja vat ly cfla khu vfle blTflChfnh - Vung May va l i n c i n , chung tdi dfla ra mpt v i i k i t l u i n sau:
1. Bp b i n do d u trflc cho toan khu vue nghien cflu b l Tfl Chfnh - Vung May da dapc c l p n h i t v l x i y dyng mdi d i n thdi d i l m hien tai d ty le 1:200.000 cho d c ranh gidi i^a chan (ting chuin) sau: nde mdng trade Kainozoi, nde Oligocen, nde Miocen dfldi, nde Miocen gifla, ndc Miocen.
2. B l d i y t r i m tieh cfla khu vfle b l Tfl Chinh - Vung M i y dat tdi 9km trong eic trung, dia hio, ban i^a h i o v i tudi t h i n h tao cfla chflng t f l Eoeen (?) d i n De tfl. Cic trung phan bd d khu vye phia Tiy, Ddng Nam va mdt p h i n d trung t l m khu vfle nghiin cflu.
3. K i t q u i nghien cflu d l xac djnh dflpc khu vflc nghien cflu ton tai 4 he thdng dflt gay chinh sau: Ddng Ble - Tiy Nam, a vT t u y i n , I kinh tuyen v i lay Ble - Ddng Nam.Trong dd, ehu dao va ehi phdi d c hoat ddng k i l n tao cung nhfl elu true la hfldng lay Bic - Ddng Nam va mdt p h i n I vT tuyen, kinh t u y i n .
4. Qua vi^c p h i n tich d i n h g l l , chung ta d l xic djnh, phan chia dflpe ele don vj d u trflc ehinh eua khu vyc b l Tfl Chinh - Vung M i y gdm 6 don vj d u trfle sau: ddi Ddng Bic b l Nam Cdn Son; ddi g i l n d i y b l l n Ddng; ddi n i n g Tfl Chinh - Phflc Nguyin - Phflc Tin; trung Vung M i y ; ddi n i n g D l L i t - D l Tiy; ddi n i n g Vung M i y - An Bang.
Cic k i t q u i trdn d l gdp p h i n l i m sing td t h i m dflpe elu true dja c h i t efla vflng nghidn cflu t r i n cP sd dd khoanh djnh dflpc d c khu vye cd t i l m n i n g d i u khi cung nhflcic ddi elu trflc cd k h i n i n g chfla d c t i l m n i n g khoing sin khic,
T i i li^u tham Ithio
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