TM chl DIA CHAT ln» J ^ »yn.nvi/lin 11 j j u

DAC BEEM CAU TRUC BIA CHAT VUNG NUOC SAU BIEN B 6 N G V B E T N A M TREN CO S d LUAN GIAI DIA C H A N

NGUYEN THE TIEP', T R A N DANG HUNG', NGUYfiN T H 6 HCJNG'. TRAN HOU T H A N ' ' Viin Dia cha va Dia vol ly biin. HoangQuic Viii. HaNoi:

'Truing DIP hgc Mo-Dia chat. DingNggc. Tir Liem. HONQI: 'Viin Diu m Viet Nam. TntongCkinh. Hi Nil

Tim lal: Khu vvc nudc sou Biin Ddng thufc vimg biin dgc quyen kmhli.dildS ngkHncuuchungsecdfnglmquanlrimgvimdtckuquybiviguyhogchpUltii/i, kink li biin Viet Nam Day cimg li mfl pkin cau Ikanh chmh cua Biin Bdng ci ift diim cdu mic - kien tgo hit sic phuc tgp. dugc kink Ihinh viphdl triin qua hkiiu giai ihgn hogt dong hen Igo trong Kamozoi Vung nghiin cdu gim cdc ddi du lm kkdcnkau vai cdc dgc dlimpbdn bi. bi diy. Ikdnkphan trim tich die diim Out ,0, va uon nip dgc tnmg cua khu vgc tdch gian biin rla Ikv dgng Ml qud pkdn IkhX Chan kku vyc vimg nudc sdu cho phip pkdn ra 10 ddi cdu Ink khdc nhau Oc m cdu true nay dugc khk tkink viphdl triin qua 3 giai dogn kiin tgo lan: tniic M gum Cmamugn - Paleocen. dong tack gian Eocen(?) - Miocen sim-giOg va mi lack gidn Miocen mufn-Dilu.

» , i * * ' ^ ^ "f" "l! '^T^' "^''' '^ '*•• '*•« w '"'"s '* " 1^ «» •^gbien doi da dgng thep Idiong man va tkdi gian Lich siipkd, triin Uin tgo -IrcmKkqi^ldmkdgc diim ki Iking ddu kki vimg nudc sou. Cdc tgp ding tick ^^^^.-O/jP^P^bifongciccdulnicdiahio. bmdiakio, ii^lkm irong dieu hmmoitntong kd chiim uu tki. Ihudn Igipkdt triin tuing trim ,fc*to

* ^ ^ * c < ™ „ g dmyen tm, H, tuang luc dia sang uu ihi dm tudng biin ning, p t o mm /wtag carhimgt thim. carbonat dgng am tiiu. cd Iki li ling ckA, gZ

S ^ "^ f \ ' ^ T "^ '^ "" ' * * «^ Miocen Ihuong - PllocenhZ LMt DAu "^'^"^'^'"'"''^'^"^^l'""^'-'^chdnc7rngktik^Z ... . . , , ° f •""tig lai. d ving bidn nudc siu life vung bien nudc sau d Bien Ddng dupc * ™ luc dia dang dupc cic nhi dja chit Vijt

M l gii li cd y nghia quan ttpng ve dia Nam het sic quan tam [5, 8, 9]. Tim kiem -chtahtti, tii nguyen vi khoing sto biin cia " i t a dd dju khi ving nudc siu nhim dinh vipt Nam. Trong nhflng nim qua, cic cdng gia tota di$n tidm ning diu khi cia nudc la

I r ° S f " "^^ ' ^ vi fliim dd tii tfttfrc xem Ii dinh hming chiin lupc diu khi nguydn khoing^ sta d cic bd ttim ti'ch Vi^ Nam ttong nhflng nim tdi 13 41 Vifc Kano™ ta ftem lyc dia Vipt Nam da ftu khtag dinh ving djc quyin ktoh ti cia nudc

A v i l r i " ^ " ^ f ^ ^^ " " ^ " "•» •= • * B i ^ Ddng hipn nay dtag li mjl S T ^ f j ^ ? ^ ^ f- ^- ' " ] • Tuy ' * ' ^ " vu rit quan ttpng vi doi hdi din vi«c S £ n^™-""™ "*'' •»« % ' ^ ' g * *vc hi^n cic cflng tttoh nghidn ciu khoa vung fliem n«rtc nong; cdn cic tii hpu khoan hpc lim bang ching. ^ kUo sit d,a chin d ving nudc siu cia M , , - i Bidn Dong cdn rit it Trong nhflng nim gin «» *^™ f T . ' ^ * "^' . ' •* ' ^ <^ diy, c i : nghidn ciu CO bin vi dinh B i k S " ^ " ^ S Wiotog sto vung biin nudc siu ning tin tgi hydmt khi, nguin ntag l u Z S , ? '^l 1^^ <» «> ^i U?u khoa hpc di

B lupng k i ^ g ^ j ^ j.|j|j ^ ^ ^ 1 ^ linh fti cia VijI

120

* Nam tren Bi&i Dong, dam bio an ninh nang lupng vi phat tiien bin vimg qudc gia troi^ tiiong lai. Tuy nhidn, do didu kien ciu true

I d^ chit ^ttn: tap vi do ban chi ve tii lidu, 1 vipc xic (finh sy phan bd vi danh gii triin

vpng tai Muydn khoing sta ving nudc bidn siu cho din n ^ van cdn nhidu vin ^ chua dirpc hiiu biit mpt cich thiu dio, cin duoc tidp tgc dieu tra, nghidn ciu.

Bii bao niy nhim myc fflch gidi fliieu m$t so ket qua mdi, chi tiit hon vi dgc didm ciu trie dia chit ving nudc sto nim ttong pham vi tpa dp 109-113° D vi 6-16° B, ttdn CO sd lujn giai dia chin. Day la mpt phin ttong kit qui nghidn cim cia Dd tii ca) Nha nudc KC 09-18/06-10 "Nghien ciu d u ttic dia chit ving nudc sto (ttdn 200 m) lim co

Mtidm nang khoang sto ving bien

iLcasdiAiuEu Ving nudc sau Biin Dong (ttdn 200 m)

cd diiu kipn dia ly ty nhien rit khd khin, ndn It dupc diu tu fliim dd, do vjy cac tai h^u dja chit - dja vgt ly va khoan lit hgn che; cic tii lipu hipn cd cflng lit khic nhau ve chit linjng, dp tin c ^ ; sy Uen kit vi lujn giii ding b$ cic tii li$u tong khu vyc cung chua dupc fliyc hipn. Phgm vi nghidn ciu ftupe nhieu bi tiim tfch khic nhau. De ftyc hipn di tii niy, hiu hit cic tii Upu dja chin dau khi hi?n cd ftuflc ving nudc siu d cic bi Phu Khinh, Tu Chmh - Ving Miy va cum be Hoing Sa, Tnrdng Sa ifi dupc s i dunn (Mnh 1).

Cic tii Upu dja chin 2D qua khu vyc nudc siu bao gdm cic tii li$u CSI^07, CSL-08, TC06, TC03, TC98, Wa74_HS, PK03 vi Seas95 di duppc s i dyng di luto giii, xic * ih ranh gidi dja ting, xay dyng cic bto dfl ciu ttuc bta di ding diy, luta giii mfli tnrdng ttam ti'ch vi dinh gii tiim ntog khoing sin.

Cic tii li$u dja chin ving bi Phi Khanh cd 3 khio sit dja chin quta ttpng l i VOR-93 ftu ni bdi Nopec nam 1993 vdi so lupng 34

tuyin va ting chieu dii l i 3592 km, mgng ludi do 10x20 km. Tiep dta l i cic tii Upu ftu DO cua Malugm (Lien Xfl cu) vdi so lupng 41 tuyin v i tflng chiiu dii 6625 km, mgng ludi tuyin 15x25 km va thu nfl ^ chin gto day cia Tdng cdng ty Tliam do Khai fliic diu khi PVEP ky hidu PK03 vdi sd lupng l i 7268 km.

Khu vyc Tu Chinh - Viuig May la ving bidn sau cia Viet Nam va l i mpt ving chua cd nhiiu tii Upu dia diit; tgi diy chi cd mflt giing khoan ftflng sd FV-94-2X dupc Tgp doto Diu khi VN khoan vao nam 1994 vdi chiiu sau ttdn 3300 m vi cd khotag 30.000 km toyin ffia chin 2D, ttong dd cd 16.700 km cua dpt khio sat TC06,2.190 km cia dot khio sit TC03, 7700 km cia dpt khao sit TC93 vi 3.700 km cia dpt khio sit TC98, cdn lgi li cac dpt khio sit trudc dd.

Do cic dpt khio ftu nfl vio cic thdi gian khic nhau vi dupc xu ly vdi cic chu ttinh khic nhau, nen chit lupng tai Upu dja chin khflng dflng diu, giy nhiiu khd khta ttong cong tac luta giii. Cic toyen dja chin Wa74_HS va Seas95 cd dp phta giii khdng cao. Cac tiiyen dja chin 2D khac nhu TC93 TC98, PK03, TC06 vi CSL-07 cd chit lupng tit vdi dp phto giai kha cao, lim ttog ftdm dp tin egy d kit qui lugn giai tai U^.

Bdn cgnh tai Upu dja chin, tii Udu cic giing khoan d cic bi ttim tich lta cta nhu 121-CM-lX 121-CS-lX (hi Sflng king); 94-PV-2X (bd Tu Chinh - Vung Miy)-Ruby-IX, Jade-lX (bi Cin Long); Thanh Long-2X (bd Nam Cdn Son) cing dupc s i dyng de Uen kit vdi tii Ueu dja chin ttong qui tiinh xic djnh cic mjt ranh gidi dja ting (Htoh 2). Vdi mOt didn tich nghidn ciu tiii rpng tien pham vi nhidu bi ttim ti'ch khic nhau nhu viy, vipc luan giii bd mjt ting mdng ttong khu vyc nghidn ciu chi yiu dya vio djc ttm^ dia chan, vi vipc Udn kit dja Chan vdi gidng khoan pip chmh xic hda tofli cia tgp dja ting.

121

m. DAC OI£M CAU TROC OIA CHAT

1. Kitqua »dn ketdfa chin

Khu vuc nghien cuu tiai rpng tren mpt dien tich bao g6m [Ji3n Icm vung th€m, suon, chan tuc <£a va trung nuoc sau ciia Bien £)dng phan bd ve phfa dong bien Tnmg B$, do do chiu anh huong cua nhieu giai doan boat dong k i ^ tao trong qua trinh tien boa cua mot bien ria dac tnmg. Cac tai heu nghien cuu tron^ khu vuc nay c5n it, thupc I^iam vi nhi6u bk tiSm tich Idiac nhau, mang hidi tai lieu lieu dja chin con thua, chat lugrig cung khac nhau do dupc thu nd 6 nhi&i thdi ky. Do vay, de iu^n giai sir phat triin cSu tnic, < a t^ng, trSm tich a day ^ su dyng phuong jiiip phan tich cac day cha tang - kien tao (tectono-stratigraphic sequence). Trong phgm vi khu vuc n ^ e n cihi xi£ djnh dupc 3 day Ion (mega-sequence) tuong ling v6i 3 ai d o ^ kiln tao chfnh la; truoc t ^ gian, dong tach giSn va sau tdch (Hinh 3). M6 hinb n^y phu hpp vdi cdc be phan b6 d ria thim lyc dja tdch gian khu vyc Biln D6ng, phan dnh sir chuyen tilp tu tdch giSn ria tich circ sang ria tl^i dOng ctia bl ria nudc sau.

/./. Mdng trudc Kainozffi: B I mSt mong dupc xdc dinh li ranh gi6i phan xa lien tuc, sSu nhat c6 thi quan sdt dupc tren cac lat cat dja chan, hinh thanh m$t mong am bpc, phan chia phdn Idt cat c6 tnronE song thi bien r6 tfnh phdn 16p cua cdc trim tfch Kaiiiozoi nam pWa trSn vdi phiin truong s6ng tu do khdng quy ludt ciia c ^ thdnh tao tnrdc Kainozoi nSm ben dudi.

Do sv h^n chl vl dp phdn gjai dia chdn d phdn mdng dya tren cac tai Ii?u t^a chdn trong khu vyc nghien ciiu, ranh gidi bl mat mong dupc phdn tich tr6n CO sd kit hpp giOa tai U^ dja c b ^ vd cdc thdng tin dia chit trong khu vyc. Ting mdng trudc Kainozoi trong khu vyc nghien ciiu dupc lien kit vdi ^ girag khoan d cac bl Sdng Hong (121-CM-IX vd 12I-CS.1X). bl Tu Chiih

Vung May (PV-94-2X) va be Ohi Low (Ruby-lXvdJade-IX).

1^. Bit chmh faqp Miocen giin: Dugc lien kit tir gjlng khoan TTianh Loi -2X thudc bl Nam Cdn Son, bit chinh hpp dupc l u ^ giai tren tdt ca cac tay^ dja chin trong khu vyc vdi die tnmg la mpt be m$t bao mdn cat xen the hi6n kha ro tren cdc m i ci ^ a chin (TC-06, TC-93, CSL-07) di qua cac bl Tu Chinh - Vung May vd Nam Cdn Son.

Tap dia chin ben dirdi ting ndy hoan tota bi chon viii trong cdc dia hao va dupc % trung bdi cdc phan xa song song din d song sdng, tm so thip din cao, dp li6n tyc tnmg binh den tdt

Ket qua luan giai cho thdy hi?n tupng nghich dao kiln tao xay ra trong khu vyc nghien ciiu kit thuc vao Miocen giiia. Sy tin tai, phdn bo rdng khip ciia cdc trim tich tnrdc Miocen giua trong khu vyc nghifin ciiu (nam ben dudi bit chinh hpp Miocen giOa) se Id mpt bdng chiing khoa hpc quan trpng trong vi?c xdc (^nh ranh gidi ngoai them i^ (£a cua nudc ta.

1.3. Bh chink hgp Miocen mupm Bit chinh hpp Miocen mu§n dupc d|c tnmg boi diu hi?u bdo mdn r5 r^ cac trim tich ben dudi mSit ranh gidi vd ben ti^n la phdn m gi day d phdn phfa tay. Ve phfa ddng khu vyc nghifin ciiu, ranh gidi ndc Miocen mugn tuong d6i khd xdc djnh, thi hi?n la mjt chinh hpp tuong iing.

Tdp dia chin ben dudi ting ndy dupc djc tnmg bdi cdc pha sdng phan x? song song den hoi phdn ky, biSn dp thip din (rung binh, dp li&i tyc tot d phia tdy, phdn xg d ^ sigmoid vl phfa biln d sudn thim. Trim tidi cua tdp ndy cd 16 dupc hinh thdnh trong m6i trudng sudn vd thim. Tren tiilm, md hlnh phdn x? cd dgng biln Iiii, cdn d viing sudn tram tich cd dgng nem iln, nhung trim tich dgng nem ldn Idn hon do t6c d$ ling dpng tram tich cao hon. Ranh gidi Miocen mu n dirpc chinh xdc hda dya ti€n vi?c lien ket,

ddi sinh cac khu vuc da cd gidng khoan d cac be Phi Khinh vi Tu Chinh - Vung May.

1.4. Bi mdt ddy biin: Dya trdn kit qua x i ly tii lipu dja chin, bi mat diy biin dupc lujn giii l i ranh gidi phin xa trdn cung cia cic mjt cit dja chin ttong khu vyc nghien ciu. Mac d i cic tii lieu dia chan d day dupc khio sat ttong cic thdi kJ khic nhau vdi cac thflng sfl thu nfl, x i \<l khic nhau, nhung kit qui lujn giai bd mjt diy bidn cho thiy sy lien kit tirong doi tflt cia cac tuyin dja chin ttong khu vyc.

Cic ranh gidi mjt mdng, ndc Miocen giia, ndc Miocen mupn vi mjt day biin lujn giii tidn cic tuyin dja chin ttong k h ^ ^ c nghien ciu dupc chuydn sang md

H ^ B c h i d u siu s i dyng tai lieu van tie ^ l ^ p T i i lieu vjn t ic cflng dupc liy t i

qui Wnh x i \-j cic tii li$u dja chin ttong khu vyc nghidn ciu v i dupc chuyin doi tiiinh cic gii tii vjn t ic tnmg binh tiieo phuong tiinh Dix ttong phin mim Geoframe-Indepth.

0 nhihig khu vyc cd cic tii l i ^ giing khoan nhu cic khu vyc tiy bic va tiy nam cia vimg nghien ciu, vi§c chuydn ddi sang chiiu siu cic ting dja chin di dupc luan giii, xiy dyng cic bin di ciu ttic di dupc thyc hi|n nhd him tic dp xic djnh dupc tten CO sd cic tii lipu toyin dja chat thing ding VSP. Dp siu myc nudc biin tiong khu vyc dupc tinh vdi tic dp tiuyen sdng ttong nudc bien li 1500 m/s.

Trdn ca sd cic tai li$u dja chin da dupc chuyin dii chiiu sau, cac bin do ciu tjio ranh gidi ndc mjt mdng, ndc Miocen giia, ndc Miocen mupn tJ Ip 1:1.000.000 di dupc tiiinh ljp lin diu Udn cho khu vyc ving nudc siu (tidn 200 m) phyc vy cho De tii cip Nhi nudc KC09-I8/06-10.

2. Phin ving ciu trie dja chit

Khu vyc nghidn ciu nim d ria phia

ddng cia khoi Dong Duong, phit ttien

chdng ttdn cic don vj can trie cia khfli nay bj boat hda kiin tao manh ttong Phanerozoi v i Mesozoi [10], v i la mpt hpp phin cua Bien Elflng chju inh hudng cia qui trinh tich gian vio Oligocen -Miocen sdm. Qui trinh lich giin nay da diy rdi xa hai khfli vi luc dja Hoing Sa vi Trudng Sa, tu do phit ttidn cic bd trim ti'ch ttdn ving fliim lyc dja Viet Nam [1]. Day la khu vuc cd djc diem ciu trie -kien tao het s ic phic tap, hinh thanh vi phit trien qua nhidu pha hoat done kiin tao khac nhau, nam tten cic miin cau trie - kien tao khic nhau bao gflm: mien ciu trie Caledonid Cathaysia', miin ria lyc dja tich gian Dflng Bic, midn vd dji duong Biin Ddng, miin luc dja sdt ttfli ttirpt hiy hoai Trudng Sa - Reed Bank.

Tren co sd phan tich cic lit cit dja chan, kit hprp vdi cic tii lipu dia chit khu vyc Biin Ddng, budc diu da xic djnh dupc djc diim he tiiflng di t giy, md hinh ciu ftic v i Ijch s i phit tiiin cia khu vyc nghidn ciu. Trong khu vyc tin t?ii 3 he flidng dit giy chinh, l i DB-TN, i kinli tuydn vi TB-DN. Dya ttdn djc diim phin bd, be diy, thinh phin trim tich, djc diim dit giy vi udn nip, khu vuc nghidn cuu da dugc phan chia thanh cic ddi ciu ttic dudi day (Hinh 6).

2.1. Dii Cau trie phta lay (A,): NSm d phan ria phia tay vung nghidn cihi, chiim mpt phin di$n tich ving, gom cic Id 124 den 135/08. Ranh gidi phia ddng cua ddi ciu trie nay l i hp flidng dit giy Kmh toyen 109 (ddi dit giy Sudn die Ddng Vidt Nam). Hp fliong di t giy kinh tii:^en niy, theo cic tai lipu dja cMn, phit tiien dpc them lyc dja miin Trung tiiupc pham vi bi Phi Khinh, kdo dii qua phin

Nhiiu Idi lilu gdn ddy cho thdy li "Caledonid Cathaysia" ihytc chdi Id mfl miln tgo nil nfi luc Paleozoi sam 1101 BBT. TCBC.

phia ddng bi Nam Cdn Son, ddng vai trfl quan trpng ttong viec hinh thinh them va suon lyc dja hidn tgi. Dac tnmg cua ddi niy l i ciu trie sut bic phat ttidn t i sudn thdm luc dja hien tai ve phia ddng. Be mjt mdng cia ddi ciu trie nim d dp sau thay ddi tii 3000 din 9000 m. Dya tidn djc didm cia can true mdng, ddi Can true phia lay dupc phin thinh ba phy ddi: Thim Di Ning (Ai-i), Thim Phan Rang (A1.2) vi Ddi eat trupt Tuy Hda (A1.3) (Hinh 6).

- Pku ddi Thim Bd Ndng ( A M ) : Phy ddi niy phit triin d phia bic cia ddi Ciu tiic phia tiy, thupc pham vi cic 16 119 ddn 128, cd phirong kdo dii gin nhu B-N, li phin kdo dii phia lay nam cua bi Sflng Hdng din ddi mrpt Tuy Hia [4, 6, 7]. Nd cd Id cfln phit triin ve phia bic, tring vdi cau true syt v i phia dflng, tap nen trung siu bi Phi Khinh. Ciu true mdng cd xu hudng ning cao din vd phia bic, dp siu cia mdng fliay doi tu 500 din 2000 m vi syt siu vl phia dflng nam vdi bi diy tram tich dat tdi 4000 m (Htoh 6).

- Phy a&i Thim Pkan Rang (A1.2): Phit triin d phia nam ddi Ciu ttic phia Tiy, gdm di$n tich cic Id 129 din 135/08, gom dipn tfch phin bic bi Nam Cdn Son vi tiy bi Tu Chfah - Vung Miy. Ngoii di t giy i kinh toyin cd vai ttd uu flie, cic di t giy DB-TN ciing phit tiiin msmh d phy ddi^niy, vdimjt dO diy hon so phy ddi Them Di Ning. Ching tsio tiiinh cic dja hio, bin dja hio hpp, phuong DB-TN. Ciu ttuc mdng nhm chung phin di m?nh so vdi phy ddi Thim Di Ning, dp siu thay dii ttr 5000 den 7000 m vi phia nam cia phy ddi.

, - Phg ddi Bdi cdt trugt Tuy Hda (Ai 3)-Nim ^ifci cic phy ddi Them Di NSng d phia bic vi 'Them Phan Rang d phia nam, d tiy nam bd Phi Khinh va li ranh gidi phia nam cia bi Phi Khinh vdi cic bi Cuu Long vi Nam Cfln Son. Phu ddi niy cd phuong ciu ttic TB-DN, l i mpt ving

cd bien dp dit gSy ldn phucmg TB-BH keo dii hing ttim km t i trong dit liin n ngoai khoi vdi bidn dfl djch chuydn ldn, cit qua cic trim ti'ch Miocen vi cim sSa vio ttong mdng. Ddi cit ttupt Tuy Hoa eo phuong song song vdi cic h | thing dut gay est trupt Sflng Hong d phia bic va Ba Chia (Three Pagodas) d phia nam. Xdt \;J hudng phit ttidn, bidn dp djch chuyio, ^ hinh thanh ddi cit trupt cd flii lidn qiai den di chuyin c ia khfli Dflng Duong do su va cham giila hai ming An Dp va Au-A .

3.2. BM Cau trie phia ddng (Kiy. ci ranh gidi phia % la hp fliing dit gSy A kinh toyin va md ipng vi phia ddng chidm di^n tich rpng Idn ving nghidn ciu. Ddi ciu ttic Ai cd phuong kdo dSi DB-TN, chju sy chi phii chinh cua qu trinh tach giin md rflng Biin Ddng trong Kainozoi. Dfl sau bi mjt mdng thay dii khi ldn tii 3500 din 10.000 m, phan dj Id tay sang dflng vi tu bjc xuflng nam. Trin CO sd djc diim h? thflng dit giy, ciu ttiic ting ldp phi, ddi Ciu tiiic phia dflng dupc chia fliinh cic phy ddi ciu tiic bjc 3 gim A2-1, A2.2, A2.3, A2-4, A2.5, A2.S vi AM

(Mnh 6).

- Phg ddi Triing ddng Phu Khdnh - nam Hodng Sa (A2.1): Phy ddi A2.1 nim vi phia dflng, qua ranh gidi phy ddi A,.| l i h? thong dit giy ldn phuong kinh toyin. Phy ddi hlnh thinh vdi djc tinh Win t?o syt lin ldn, dill gay ho|t dpng nhidu pha chiim uu Ihi, mdng nSm d dp siu Idn t i 7 din 10 km (kS ci chiiu siu nudc biin), kdo dii theo phuong DB-TN. Cd thi do inh hudng cua dfl sau cia nudc bien vi bi diy Idp phi ldn; lanh gidi mflng xac djnh tidn cic tii Upu dja chin d khu vyc niy khflng dupc rfl ring. Bi day tiim ti'ch Kainozoi phi trdn mdng cd Ihi dat tdi 6000-7000 m. Cic ddi dit giy Irong phy ddi l i cic dit giy ldn, xuit phit tir uong mflng cit phit triin tdi ndc Miocen ttung, cd phuong tling vdi phucmg ciu tnic, thi nim chi yiu cim vi dflng bic (Hhih 4 & 6).

Hinh 1. Vi tri cic myen khio sal dia chan khu \vc nghien cm.

Hinh 2. Ranh gidi dfa chdn duoc Hen ket v&i giing khoan Thanh Long-2X (bi Nam Con Son. tuyen dia chdn TC98'041).

Hinh 4. Lat cat dia chdn tuyen CSL 07-11 qua cdc phy d&i cdu true A2.1, A2.2 vdA2-3

Hinh 5. Ldi cdt dfa chdn tuyin TC06 40 qua phu ddi cdu irucA^.

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I A ^ . ] Bdi ln«t Tuy Hoa

H ^ g TiOng £)dng Phu Khinh v i Nam HoSng Sa

^ ^ 1 Ddi nang tmng tam vung nghidn ciu

^ ^ 1 TrGng phin dj phia ddng

^ ^ 1 Triing edng TU Chinh

j ^ ^ l Phin phia Nam dja hdo Quang Ngii

^ ^ 1 Ddi ning Tri Tdn_Nam Hoing Sa

1 ^ 1 TrOng biln thim(Vung bdc 16 tich gian Bi n Ddng)

Hinh 6. Phdn viing cdu Iruc dia chat vimg nudc sdu

Phu ddi Nang trung ldm (A2-2): Nim ve phia dflng phy ddi A2-1, gflm cic 16 151,152 vi mflt phan Ifl 129, cd phucmg kdo dii DB-TN. Mdng phan dj manh, nim d dp sau thay doi ttong khoang 5-7 km. Trong qua tiinh tien hda, phu ddi bj chia cit flianh nhieu khii cau tiic nhfl bdi hp thing dit gay chi yiu phuong DB-TN, lao nen mpt s6 dja hao, ban dja hao hpp phit triin xen kpp, dupc lip diy bdi cac tiianh tao Eocen-OUgocen-Miocen ttung vdi bd diy khflng Idn, khoing 4 - 5 km. Cic thanh tao Miocen thupng, Pliocen-Dp Hr hhih thinh ttong giai doan lin chim khu vyc; ranh gidi bi ttong giai dojn nay bj xda nhoa.

- Phu ddi Triing pkdn di phia ddng (A2-J): Chiem didn Hch ldn fliupc pham vi cac Ifl 152, 153, 154 vi 155 vi mdrong ve phia ddng, cd ranh gidi phia lay li phy ddi Ning ttung tam A,.,. Phy ddi cd dang long ming, phit ttien md rflng vd phia dflng bSc va tiiu hpp din vd lay nam Be mjt mdng phin dj phic tap, nSm d dfl sJu thay ddi ttr 6 den 7 km, bj chia cit bdi hd

thflng dut giy phuong BB-TN, gdm htog loat cic dja hio hinh thanh Uen quan din khoi dut ^ly nghieng (tilted-fault block). Bi day ttJm tich toong dii mflng, thay dfli khoing 3- 4 km (Hinh 4 & 6).

- Phv dm Triing ddng Tu Chinh (A24): Diy la phin phat tiiin ria phia dflng nam ciia be Tu Chinh - Vung Miy, thupc ph^m vi cfc Ifl 131, 132, 134, 135, 156, 157, 157 vi 159, vdi hp thong dit gay uu flii DB-TN vi a kinh tuyen. Phy ddi cd djc didm ciu trie hoin toin khac bipt, ngan each vdi cic phj ddi d phia bac bdi hp thflng dit gay sau TB-DN, gom nliiiu ciu ttic ning va sut bjc 4 (Hhih 5 & 6). Dja hmh mdng phan dj manh. CO dp sau fliay dii t i 5 din 10 km, chim din ve phia dflng nam. Cic dit gay ttong phy ddi niy diu la dit gay thujn, huih thinh chiiii yiu ttong flidi ky tich gian Oligocen-Miocm sdm, sau dd hopt dflng lai sau flidi ky tach gian thi hai vao Miocen giira va hau hii ngimg nghi vao cufli Miocen giia, phil trien chu yeu flieo hudng DB-TN.

Ngoii cic di t giy tre, ttong ddi niy cdn cd nhieu di t giy c6 hinh thinh tnrdc vi tii hoat dpng vio thdi ky tich gian sau nay. DJy l i cic dirt gay phit tiiin chi yiu hudng a kinh tuyin. Chiiu diy tiim tich Kamozoi d phu ddi niy dat tten 7000 m d cho sau nhat v i trung binh khoing 3500 den 4500 m, vdi thanh phin trim ti'ch chu yeu li cic vun lyc nguyen cat, bpt sdt v i carbonat trong cic thinh t ^ todi Eocen (?), Oligocen, Miocen va Pliocen - Dp tft. Cic trim tich niy hinh thinh vi phit triin trong cic mfli tnrdng ddng bSng chau thfl, bien vi biin nflng; lip dky cic trung v i cic thinh tao sau Oligocen chu yiu i i cic tram ti'ch bien, phi bit chinh hpp ldn trdn.

- Phv ddi Nam djo hda (Sudng Ngdi (A2-s)^Umpt ifla hio hpp va l i phin dudi phia

^ ^ ^ P bi Sflng Hong, nim kpp giia thim Di NSng vi ddi ning Tri Tfln vi ttidng vdi be nudc sau Phi Khanh d phia nam (Hmh 6). Dja hao cd ciu ttiu: don gian vdi hhih mjt cit ngang nhu mflt 18m sau oSn vflng. Tram tich trong dja hao nay cd thi diy den 8-9 km, bao gom cic tiim ti'ch tu Eocen den DJ tii. Djc bidt pha phun trio cuii Miocen-Pliocen hojt dflng mjnh lpi day, nhit li phin phia tay Ifl 120. E)ia hao Quang Ngai 14 mpt ttong nhOng ving smh diu khi chmh cia phin phia nam bi Sflng Hing.

- Phv ddi Ndng Tri Tdn - Nam Hodng Sa (A^: L i ddi nhfl cao cia mdng d phia nam bi Sdng Hong, cd dfl sau mdng khoing 2-4 km, phuong ciu ttic DB-TN vi chuyin din sang i vi toyin d phia ddng, ti<n dd cd ldp phi trim tich vyn Oligocen, di vfli ndn vi cic khoi xiy carbonat toil Miocen giia-mufln. Theo cic kit qui nghidn ciu gin diy, phy ddi nijf cd chiiu dii khoing hon 500 km, phin phit hien r^ng va cao nhit l i d Id 120-121, sau khi qua cic Ifl 117-118-119 till nhd din vi chim viphia bic Ifl 113.

Thyc t i v i ^ ting hpp cic tii Udu hidn cd cia Vipt Nam d khu vyc niy cho fliiy

phu ddi A M khong diing lai d nam Ifl 115 nhu mpt sfl cflng bo trudc day, m i thyc te con phat triin khi rfl din 16 113 vi phia bic ciia viing nghidn c i u Do phin niy cia ddi nang nam d dp siu Idn vdi mfli trudng bidn sau ndn cic trim ti'ch carbonat khflng cdn diy, hon the nia tren ddi nang phi mpt ldp set Pliocen - Dd t i day (khoang hon 1000 m), ndn vide quan sit nd ttdn mjt cSt dia chin se khd khin hon so vdi ving phia nam. Mpt loat cic phit hipn khi trdn ciu tao khoi xay carbonat/san hfl im tidu d phy ddi niy cho thiy, day l i ting chfta diu khi tiim nSng cia ving, cd chat lupng tit vdi nhu da fliiy d mpt sfl giing khoan: 119-CH-lX, 118-CVX-lXvill8-STB-lX.

- Phv ddi Triing biin thdm (Viin^ bfc If Idch gidn biin Bdng - A2.7): NSm d phin phia dflng bic c ia viing nghien ciu; dSy l i ving cd dfl sau mong ldn vdi chiiu sau eye dai din 10 km (ki c i chiiu sau myc nudc biin). Ving bj chia cit chi yiu bdi he flidng dirt gSy phuong DB-TN vdi bidn dfl djch chuyen khoing vii ttSm den 1000 m, chi yiu cim ve hudng DB v i TN tao thanh cic dja hao hpp, keo dii hing vii ttiic den ttim km. Bd day ttim tich Kainozoi khoang t i 1000 din 3000 m, vdi djc ttyng cia trudng sdng dja chin tuoiig dfli fln djnh, phin ldp nim ngang. Thinh phin thjch hpc chi yiu l i bazan, d i sdt tudng biin sau, tudi Miocen giua-mufln den Dp tft.

IV. L|CH Sl> P H A T TRltN OjA C H A T

Djc diem nil bjt v i vfl cung cd ^ nghia hong ljeh sft phit tiiin dja chit ttong Kamozoi d lyc i j ^ Dong Nam A nfli chung, v i Vipt Nam ndi rieng, l i sy hinh flianh eic hi trim tich cd tiim ning diu khi ldn. Ving nghidn ciu fliuflc vung nudc siu fliem lyc dja Vi$t Nam hinh thinh ttdn cic don vj kiin tjo khic nhau vdi nguin gic, diiu kipn dja dpng lyc khic nhau, nhung cic giai dojn phit ttiin

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kien tjo - trim ti'ch ldn vin mang nhing tinh tuong ding khu vyc vi ttien vpng diu khi rfl rdt

1. Giai dojn tnrd« tich giin (Creta mu$n - Paleocen?)

Vio Jura mupn - Creta sdm (?), ria dflng cia lyc dja £)dng Nam A phit tridn kieu ria lyc dia tt'ch eye Andes, hit chim cia vd dai duong bdn dudi ria lyc dia phia ^ng Viet Nam vi nam Trung Hoa, hinh thinh cung magma lyc i£a, tao ndn cic phftc hd magma xim nhjp axit, phun trio kiim-vfli [10]. Cic thanh tao granitoid, phun tiio axit -ttung tinh, di bien chit thip - tnmg bmh Ip ra d ria tien lyc dja, dupc xem li tiianh tjo cia mdng cic bi phit triin tidn ria fliem phia dflng Vipt Nam.

Do hjn che cia chit lupng tii lipu phin dudi siu cia ving nghidn ciu, rit khd cd thi xic djnh cic thinh tjo trudc t^h giin. Cic tii lipu dja chin cho tiiiy bi mjt ting mflng ed bidn dp phin xj mjnh, do sy khic bipt ldn vi trd khing Sm hpc so vdi Idp phi ttim ti'ch phia ttdn. MJt mdng tiiudng li ndc cia mpt tjp dja chin khflng cd phan xj hojc cd bidn dp phin xj rit tiiip.

Kit hpp vdi vijc khio sit cic vit Ip dja chit, dya tren cic tii lipu vi mdng d cic bi trim tich ttdn fliim luc dia Vipt Nam, cd tiii dy bio ttiinh phin di mdng ving nghidn ciu gim cac di granitoid, di biin chit yiu, cd tiii cd it di ttim tich. Di mdng nit nd tiirdc Kainozoi d cic bi Ciu Long vi Nam Cfln Son diu di cd cic md vi phit hipn diu ttong mflng. Tuong ty nhu cic bi niy, di mdng ving nghidn ciu dupc xem li dii tirpng chfta diu khi tiim nSng.

t-kJenglC"'*"'"""""'^"°"'-Tidu chi di xic djnh pha ding tich

^ li sy cd mjt cic diy tiim ti'ch ding lain tjo (syn-tectonic sequences), gim eic phin XJ khflng lidn tyc, bidn dp cao

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dupc khflng che bdi cic dftt giy. Mjc dil cd nhing khic bipt ttxmg qui ttinh hink flianh giihi cic bi, giai dojn dong tich giSn syn-rift trong vung cd Id bit Iffiu vio diu Eocen(?), tiip tyc trong Ohgocen vi kit tilic vio cuoi Miocen giOa, cfl life quan din qui ttinh tich giSn vi hhih thinh Biin Dflng ngiy nay.

Dj thirdng tu dfli xihig d trung tim Biin Dflng khing djnh sy tin tji vd dji duong. Sy phan tich dj ttudng tii, dja huh diy biin va cic tii li u khoan cho tiiiy vi dpi duong cd tail Oligocen - Miocen giOa (32-16 Tr.n.) [1]. Tach giin diy dji duong hinh ttianh Biin Dflng xiy ra ttong nhidu pha, cing vdi sy thay dfli tiyc tach giSn, chuyin dan vi phia nam. Pha llch giin diu tidn dien ra vio khoing 32-26 Tr.n., tich giin xiy ra d phin phia bic cua Biin Dflng hijn tji, vdi phuong tiyc tich giin DN-TTB. Ti 26 din 16 Tr.n., tilic tich giSn chuyin din vi phia nam, ' tich giin mjnh d phia tay nam Biin Ddng hijn tji, vdi phuong tryc DB-TN [I].

Doi vdi cic bi d phia nam nhu bi Nam Cfln Son, Tu Chinh - Vung Miy, giai dojn ding-rift niy cfl flii chia 2 ttidi dojn, phan cich nhau bdi mpt flidi gian dii nging nghi tiim tich, dd li: flidi dojn tjo rift sdm (Eocen(?)-01igocen) vi Ihdi dojn tjo rift mupn (Miocen sdm-gifla) [2]. Dii vdi cic lit cit dja chin qua phin phia DB ving nudc siu flii khdng xic djnh dupc rfl 2 flidi doan niy.

Thdi dojn tjo rift sdm kdo dii ttong suit Eocen(?) vi Oligocen. Diy li flidi dojn quan ttpng ttong qui ttinh hinh tiiinh cic dja hio, bin dja hio d ving niy vi hing lojt cic dit giy ttiujn di htah ttiinh do lyc cing tich tjo ndn ti*n loin b§ dipn tich ving nghidn ciu. Cic him Uch lip diy cic dja hio, bin dja hio IJ cic tiiinh tjo vyn lyc nguydn, gim cit-bjt ket, sdt kit giiu vjt chit hOu co vi flian

* Idiig dpng trong mdi tnrdng luc dfa sdng-* ho, chau tho va bien ven bd.

; Trong thdi doan t ^ rift muon vdo cudi Oligocen, vung nghien cmi duoc nang len n^mh mg va xay ra mpt qua trinh ngung nghi tram tiich, dan den mpt giai doan phong boa yd bao mdn trudc kbi xdy ra m0t pha bien tidn vao ddu Miocen ^rm, mdi trudng bien phat triSn ^ n g k h ^ todn khu vvrc. Cdc trdm tich Miocen ha hinh thdnh, gom chii yeu Id bpt kdt va set k6t xen ke cdc Idp cat kdt bEit mjn, phu bdt chinh hpp len tram tich Oligocen. Vao tiidi doan nily, cac diit gSy lai tai bo tt dOng m ^ ldm cho viing nghien ciru tiep tyc dupc md rpng ra cac phia, vd ciing chinb trong thdi doan nay h? thdng diit

i^ a kinh tuyin hoat dOng manh mg cilng "ldng dut gay DB-TN.

D ^ di^m moi trudng tram ti'ch cd xu hudng thay doi theo thdi gian cung nhu khdng ^an tiJr phfa tay vd nam v^ phfa DB ddi tdch gidn ddy Bien Ddng. Trong giai do^n dong-rift, hku het di^n tich hh Curu Long ndm trong mdi trudng I\ic d}a soug­ht, mdi trudng bign ven bd xuit hi$n d cdc bg Nam Cdn Scm, Ddng Natuna; ddy dupc xem Id giai d o ^ hinh thdnh tdng dd sinh dku khi chinb cua cdc b^ kieu tdch gidn ria tii^m khu vvc DN A.

Pha v ^ dpng kien tao ndng vdo cuoi Miocen gifta da c h ^ diit hodn todn giai d o ^ dong tdch gidn. Trong ving nghien Clhi, bat mu tu Miocen gifta pho bi^n mdi tiirtmg bien ndng den them ngoai, t^o di^u ki^n thu$n lpi cho sv phdt tt-ign cdc dm tigu san hd trgn cdc vung nhd cao. Cac thdnh t^o carbonat dgng nen hinh thdnh lign quan den cdc pha bign tien Miocen gifta-muOn dupc danh gia Id t ^ g chfta d^u khi quan trpng d cdc hk Nam Cfln Sera, Phft Khdnh vd Tu chfnh - Vung Mdy.

^ Vdo gSn cu6i Miocen gifta, trgn m$t cat dja chan cd tii^ th4y mOt m^t bit chinh

hpp gdc, cac trdm tich bi bao mdn, cat cut manh mg lam gian doan trdm ti'ch iSt ldn. Mat bat chinh hpp bao mdn nay phdn anh mpt thdi figm r ^ dac trung d tat ca cac bl phia Nam Vipt Nam, tuong ftng vdi thdi diem I ^ thftc tach ^3n day dai duong. Mat bat chinh hop Miocen gjSa nay quan sat rd nhat d nhung tuyen dia chan ndm dpc theo ria ddi tach gidn Biln Ddng.

Tren binh do cau true vung ddng bdc khu vuc nudc sau thg hign rat r5 su hogt dpng kien tgo nghich ddo da xay ra vdo dau Miocen gifta, Iam binh dd cau trk: cfta vftng thay ddi hodn toan so voi thdi ky tnrdc dd. Trong Oligocen va Miocen sdm, nhung vung trudc la dia hdo thi nay tid thanh dia luy ho§c bdn dja luy vd ngupc lai.

3. Giai dc^n sau tdch gian (IMiocen mu^n - 0$ tD>)

Tigu chi chfnh dk xdc dinh day ndy Id cac trim tich dang ldp phft t : ^ mgt bit chinh hpp Miocen gifta vd khdng cd hogt dpng dlit gay c8t qua. Mpt so dftt gdy xuygn cat qua cic dSy tiim tfch sau tdch gian, tuy nhign chftng thudng Id dftt gSy nhd vd khdng phdn dnh mftc d$ cdng gidn ldn. Phan dudi cua t |p h|iu-rifl tiiudng Id ttidnh tao tudng bien sdu rit rd (pelagic fecies), phdn dnh dieu kien thdnh tgo giai doan be da budc sang giai dogn ngftng ngbi tdch gidn vdi toe dp Iftn chim nhanh cftabl.

Pha bien tien dau Pliocen diln ra ti-gn todn bp tiilm lyc dja Vift Nam. Biln ddng len trdn ngap todn bp khu v\rc rOng Idn ndy. Vgt li?u tram tich di^rc v|ln chuyin tft xa din gom set, bdt vd cdt phft bit chinh hpp lgn cdc tram ti'ch Miocen. Cdc ti^ tich Pliocen - Df tft hinh tiidnh tiong dilu ki?n dpng nang ylu, tao ngn cdc ldp gdn nhu n3m ngang, cd dac trimg phdn xg lign tyc, 6n dinh vd hiu nhu khdng bj cdc dftt g§y pban c k Chl dp kiln tgo bhih hn cho phgp hinh tfidnh cdc trim ti'ch hgt mjn

131

l i ldp chin quan trpng cho cic tich ty diu khi niu cd d vimg niy.

Sy phit tridn cic trim ti'ch cua thdi k^ niy dS xoi nhoa ranh gidi giira cac vung trong khu vyc cung nhu giia cic bi trim tich vdi nhau, tao nen mpt sy thong nhit tidn toin bp them luc dja Vidt Nam v i ving ke can.

V. KfT LUAN

Ving nghidn ciu thupc ving biin nudc sau (trdn 200 m), trii rpng t i thdm. sudn lyc dja den triing sau Bien Dflng thupc khu vyc biin miin Trung, vdi nhing djc tiimg cua nhflng ciu ttic hit sic phuc tjp vi da dang.

Qui tiinh phit tiiin cia Biin Dflng dS tjo ra hai ddi cau trie cliinh ttong ving, gflm ddi cau trie phia tay vi ddi ciu trie phia dflng. Ddi ciu trie phia tiy dupc djc ttung bdi cic phy ddi Thim Da Ning, Thim Phan Rang, Ddng bi Nam Cfln Son - fay bi Tu Chinh -Ving May vi phy ddi Cit tti^ Tuy Hfla. Ddi cau tiiic phia dflng gom mpt lojt ciu tiiic nang va hj dan xen nhau: Trung Dflng Phi Khinh -Nam Hoing Sa, phu ddi Ning Trung tim, phy ddi Trimg biin fliim, phy ddi Phin dj phia dflng, phy ddi PhSn dj DSng Tu Chinh, phy ddi Nam dja hio Quing Ngai, phy ddi NSng Tri Tfln - Nam Hoang Sa.

Ljeh s i hhih ttiinh ciu tiic dja chit khu vyc dS ttii qua 3 giai doan ldn mang Unh juyit djnh nhOng ndt co bin cia binh do cau tiic cia khu vyc: giai doan ttudc tich giin (Creta mufln - Paleocen ?), giai doan ding tach giSn (Eocen ? - Miocen giiia) v i giai dojn sau tich gian (Miocen mufln - Dp tii). Moi giai doan ddu tiio ra dSu an ridng ve chi dfl kiin tao, ciu trie dia chit vi djc didm mfli ttudng co dia ly Dva vao nhing djc flii niy, chung ta cd the djnh hudng cho vide dy bio cic loai tai nguydn vi khoang sin cia vung nghien cuu. •

VAN U^U

1. Briais A., Patriat P., Tapponnier P., 1993. Updated interpretation of magnetic anomalies and sea-floor spreadmg stages m ttie Soutti China Sea: Implications for flie Tertiary tectonics of Souttieast Asia. J. ofGeopk. Res, 98/B4 • 6299-6328.

2. Lee G.H., Lee K.,WatkiBS J.&, 2001. Geological evolution of the Cuu Long and Nam Con Son Basins, ofFshore Souttiem Vietiiam, Soufli China Sea AAPG Bull, 85 :1055-1082

3. Nguyin Thinh Van, Trin Vihi Trj, 2007. Mflt so tiiflng tin ve diiu tra hydrat khi. TC Bia chdi, A/301:100-103 HdNfi

4. Nguyin Th i Hing (CAii biln), 2008. Pettoleum geology and hydrocarbon potential of Phu Khanh Basin and adjacent areas. Bdo cdo Di in. 52p.. Luu trii VPI. HdNfi

5. Tr in Ding Hing , Vu Ngpc Dim, Nguyen Trpng Tin, 2008. Didu kidn dja chit hinh thinh hydrat khi. TC Ddu khi tr. 26-29 Hi NfL

6. Trin Hihi Than (Chi biln), 2009. Lujn giii dja chan khu vyc nudc siu biJn Dflng Vijt Nam. Bdo cdo chuyin di, 60 Ir.. Luu ira VPI, Ha NfL

,,..''• ^'»^" '*89? TpSn, 2007. Hydrat khi: Ngudn khi dit tidm nSng cua ttii k« 21.TCDdukhi, 1:42-48. HdNfi

.,„•'.: T d ; Ng|pe Toin, Nguyin King Mmh, 2007. Bi ttim tich Phi Khinh vi tii nguyen diu khi. £)/o chdi vi tin nguyin ddu khi Vill Nam, tr. 241-268. Nxb KH&KT. Hi NfL

9. Tr in Ngpc Toan, 2008. Hojt djng diu klii ving nudc sSu d Ddng Nam A. TC Ddu khi, Ir. 30-32. Hi Nfi.

10. Tr in Vin Trj, Va Khue (Bing chu bien), 2009. Dia chit v i lii nguyta Vipt Nam. Cue Bia chdi va Khoing sm Viet Nam, 590 trg.. Hd Nfl

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SUMMARY Characteristics of geological sttucttire of deep sea area in the Viettiamese East Sea

based on seismic interpretation Nguyin Thi Tilp. Trdn Bdng Hiing Nguyin Thi Hung Tran HOu Thdn

Deep-water sea area of the East Sea belongs tti tiie Exclusive Economic Zone (EEZ) of Vipt Nam, ttieiefore its stiidy has a very miportant significance on ttie sovereignity and marine economic development planning. It is also flie principal constitiient of Vietiiamese East Sea with a very complex tectono-sttuctiual characteristic and undergone various tectonic stages during Cenozoic.

The stiidy area is composed of different stiiictiual zones wifli tile disttibution fliickness, sedmientary composition, faulting and foldmg characterizing ttie extentional zone of passive margmal sea. Cenozoic sedimentary formations of great ttiickness were formed m diversified in time and space environments. Tectono-sedimentary evolution controled ttie hydrocarbon system of deep-sea region. Eocene(?)-01igocene syn-tectonic sequences distiibuted mainly in graben and half-graben sttuctiires were deposited -lamly in dominant lacusttine medium, favoring ttie occurrence of organism-rich fine-

lined facies, regarded as important hydrocarbon source rocks. Lower-Middle Jiocene sequences are characterized by ti^nsitional facies irom dominant contmental conditions to marine medium witii wide developmem of carbonate platform and reefal facies, which may become a significant reservou. Fine-gramed facies of Upper Miocene - Pliocene post-nft sequences formed in ttansgressivc and high system ti^cts may play uie role of regional seals.

The results of seismic inteipretation allows us to divide tiie deep-water region of East Sea into 10 different tectono-stiiictiiral zones. These zones were formed and developed through tiuee extensive tectonic stages, such as Cretaceous-Paleocene pre-rift Eocene(?)-Middle Miocene syn-rift and Late Miocene-Quaternary post-rift stages.

Ngudi biln tfp: Tran Vdn Tri.

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