Tuyin tap bao cao Hoi nghj KHCN "30 nam Dau khi Viet Nam Co hoi moi, thach thuc moi" 239 QUA TRINH PHAT TRIEN CAU TRUC CUA PHAN BAC BE SONG HONG TREN CO SO MINH GIAI TAI LIEiU DIA CHAN Bill Thj Thanh[.]
Tuyin tap bao cao Hoi nghj KHCN "30 nam Dau Viet Nam: Co hoi moi, thach thuc moi" 239 QUA T R I N H P H A T TRIEN CAU T R U C CUA P H A N B A C BE SONG H O N G T R E N C O SO MINH GIAI TAI LIEiU DIA C H A N Bill Thj Thanh Huyen Yasuhiro Yamada, Toshiftimi Matsuoka Dgi hpc Tdng hop Kyoto TOM TAT Bi Sdng Hdng cua Viet Nam la mdt be trdm tieh trugt bdng, tdch gidn diin hinh vd dugc chia ldm phdn chinh: viing trung Hd Ndi & phia tren ddt liin, phdn Bde vd Nam be Sdng Hdng & ngodi khoi vinh Bde bd Su hinh thdnh vd cdu true dia chdt ciia nd bi dnh hu&ng true tiep b&i cdc chuyen ddng dich trugt ciia dut gdy Sdng Hdng vd su tdch gidn ciia biin Nam Trung Hoa sinh sir va chgm giua mdng An - Au th&i ky Kainozoi Hinh dgng keo ddi eua be trdm tich Sdng Hdng bi khdng chi mgnh b&i he thdng dut gdy Sdng Hdng vi hai cdnh phia Ddng - Tdy Cdc sd lieu dia chdn thu dugc & be Sdng Hdng da dugc su dung tu cudi nhirng ndm 1980 viec tim kiim cdc cdu tgo ddu triin vgng Nhu chiing ta da biit, cdc sd lieu dia chdt, dia vdt ly khdng chi chua dung nhung thdng tin cd ich cho viec thdm dd ddu md cdn luu giir nhirng thdng tin gid tri ve cdc cdu true ndm sdu ldng ddt, ddc biit la nhung thdng tin chi tiet ve su phdt triin kiin tgo cua bi Trong bdo cdo ndy, chung tdi gi&l thieu cdc kit qud nghien ciru ciia minh vi xdy dung cdc bdn dd cdu true, bdn dd ddng ddy qua minh gidl cdc tdi lieu dia chdn & phdn Bde be Sdng Hdng, ngodi khai vinh Bde bd Cdc kit qud ndy cho thdy ro kiiu cdu true eua bi vd cdc dirt gdy phdt triin mgnh khu vuc nghien ciru cd sau Miocen mudn, vi phdn Ddng Bde cua be Nghich ddo kiin tgo xdy Miocen (mgnh nhdt Miocen gida) v&i su hinh thdnh nhiiu cdu triic hinh hoa duong vd dm diiu kiin udn cong vd nen ep ngang Them nil'a, chiing tdi cdng dd kham phd thim vi qud trinh tiin triin dia chdt vd kien tgo dge biet la su phdt trien cua hi thdng dut gdy & phdn Bde bi trdm tich Sdng Hdng tir minh gidi cdc tdi lieu dia chdn cimg nhu tdi tgo lgi cdc qud trinh kiin tgo ddng luc cua nhirng mat cdt dien hinh Cdc kit qud nhdn dugc tir nghien ciru ndy se dugc lay ldm tham sd ddu vdo cho nghien cuu tiip theo ciia chimg tdi dd la dung phuong phdp cdc phdn tu rieng biet - Discrete Elements Method (DEM) di xdy dung md hinh sd eho su dieh trugt ciia dirt gdy Sdng Hdng th&i ky Kainozoi dnh hu&ng eua su va chgm eua mdng An Do vdo mdng A - Au SO LUOC VE BE SONG HONG TRONG BOI CANH KIEN TAO KHU VlJC • • • Sy hinh be S6ng H6ng co lien quan mat thiet voi sy va eham ciia mang An Do vao mang A - Au Khoang 80 trieu nam ve truoc, mang An Do bat dau tr6i dat vl phia mang A - Au o ban cau Bae (Dewey va n.n.k., 1989) nhung sy hgi ty thyc sy cua hai mang luc dja bat dau khoang 45 - 50 trieu nam vl truae tao nen dai pha hiiy va cham bao gIm Tay Tang va Himalaya (Avouac va Tapponier 1993; Le 240 Qua trinh phat trien cau true ctia ph^n Bae be Song H5ng tren co- s6' minh giai tai lieu dja chan Pichon, 1992) Tiep theo sau do, lop vo lyc dja Tay Tang bj thiic trugt ve phia D6ng Nam ket hgp vol sy quay ngi mang ciia kh6i Nam Trung Hoa va khii D6ng Duong da gay djch trugt trai ciia dirt gay S6ng H6ng (Hall, 1996) Doi dirt gay S6ng H6ng la ranh gioi gitra mang Nam Trung Hoa va D6ng Duong va nam tren phan Bae lanh th6 Viet Nam, trai dai hon 1000km tir-cao nguyen Tay Tang ve phia D6ng Nam phia vjnh Bae bg da hinh nen be-tram tieh S6ng H6ng ngoai khoi them lyc dja Viet Nam khoang 32 trieu nam truac day -Trugt bang trai ciia diit gay S6ng H6ng co the la nguyen nhan ehinh tao sy tach giarr bien D6ng (Taylor va Hayer, 1980, 1983) Djch trugt trai cua dirt gay S6ng H6ng ket thiic vao khoang 17 trieu nam ve truoc va sy tach gian bien D6ng eting ket thiic khoang 15,5 trieu nam truoc day Sy hiit chim gan day ciia lop vo dai duong bien D6ng ve phia vyc Manila eo the duge coi la nguyen nhan gay trugt bang phai ciia dirt gay S6ng H6ng bat dau tir khoang 5,5 - trieu nam ve truoc (Hall, 1997) Co che djch trugt ciia dirt gay S6ng H6ng da thu hut sy quan tam nghien ciru cua nhieu nha khoa bgc Viet Nam ciing nhu the gioi nhung hien van nhieu van de t6n dgng dang can lam sang to Sy trugt bang cua dirt gay S6ng H6ng va sy tach gian bien D6ng eo anh huong rat nhieu den cac hinh thai cau true ciia hau het cac be tram tich o Viet Nam (Huyen, 2003) Hinh ehi vj tri dia ly va dja hinh ciia doi pha buy tao va cham ciia mang An Do vao mang A Au, dirt gay S6ng H6ng va bien D6ng Hinh 1: Dia hinh cua doi hoi tu giira mang An Do va A - Au (theo Metivierm 1996) B I S6ng Hing la bl trdm tieh De tam Ion nhdt Viet Nam bao gIm viing triing Ha Noi tren ddt liln keo dai phia ngoai khoi thuge vinh Bde bg No co thi dugc coi nhu mgt b6n trung keo tach diln hinh dugc ldp ddy khoang 15.000m trdm tich De tam o phan Trung tam cua be vai chu ylu la cae trdm tich vyn, cac da v6i tuli Miocen va eae tram tich nui lira cae dja tdng tuli Pliocen-Pleistoeen dugc phat hien thdy phdn Nam eiia be Hinh chi cac don vj cdu true chinh eiia bl S6ng H6ng Sy phat triln kien tao va hinh dang keo dai ciia no bj khing cbl boi cac boat dgng trugt bdng eiia Tuyin tap bao cao Hoi nghj KHCN "30 nam DSu Viet Nam: Co hoi moi, thach thuc mdi' 241 dirt gay S6ng Hing anh huong eua nhieu pha kien tao kbac va co the tom tat nhu sau: • Thai ky tach gian som: Pha tach gian dau tien be S6ng H6ng xay Eocen - Oligocen vai t6c lang dgng tram tich cao cae dja hao va ban dja bao Da s6 cae khu vyc bj boc mon va 16 kh6ng khi, chi co mgt vai dja hao dugc lap day boi cac tram tich dam h6 va cac b6i tich s6ng Cac tram tich vun th6 tich ty ven suon ciia be cac tram tich hat mjn lang dgng lai Trung tam ciia bl • Pha tach gian mugn: Xay Miocen som va Miocen trung Be S6ng H6ng tiep tyc liin chim, cac dja hao, ban dia hao dugc mo rong voi tram tich chii yeu la cat ket va set ket • Pha sau tach gian: Thoi ky dugc dac trung boi cac dau hieu phan xa ga day tren cac mat cat dja chan, co the bat dau tir Miocen trung va Miocen mugn vai cac boat dgng nen ep ngang va cac pha nghjeh dao kien tao a nhtrng noi co cac chuyen dgng chom nghjeh xuat hien Cac vom set hinh giai doan cung dugc quan sat thay tren nhieu mat eat dja chan a khu vyc nghien ciru 10»C 108^ 110^i -1 Ut Hinh 8: Ban cau true thoi gian cho noc cua Mong (buoc ve 250ms) Hinh 9: Ban cau true thoi gian cho noc Pliocen (bu-ffc ve 100ms) Hinh 10 chi ban d6 dang day cua tap trSm tich Oligocen Nhirng noi ma trSm tich Oligocen bi bao mon irng voi nhirng vj tri nh6 cao ciia mat mong nhu da dugc chi tren mat cat dja chSn Hinh Cac trSm tich Oligocen, tir dAt liln din ngoai khoi, tir vimg ria be cho tai Trung tam ciia khu vyc nghien ciru eo chilu day thay d6i tir - 1500m Hinh 11 la ban d l dang day cho tr§m tich Miocen gitra Chiing ta CO thi nhan thdy ring, trim tich Miocen gitra eo mat a gin nhu toan bg bl, nhien a nhti-ng khu vyc mong nh6 cao thi chilu day trim tich ciia chiing giam di Chieu day tram tich thay d6i tir khu vyc qua khu vyc khae tren ca cac mat cit va ban d6 eho thay ring, chimg da phai trai qua qua trinh pha buy nghjeh dao kiln tao manh me 247 Tuygn tap bao cao Hoi nghj KHCN "30 nam Phu Viet Nam: Co' hoi mdi, thach thiic moi" I I I I I I I IM ^ V v - f y I -I II Hinh 10: Ban dang day cho tap tram tich Oligocen (buffc ve 100ms) M - I I iM'^Nr^'K' I I I I Ij Hinh 11: Ban dang day cho tap tram tich Miocen giu'a (buffc ve 100ms) KHOI PHUC LAI Sir TIEN HOA KIEN TAO • • • • Cac ket qua minh giai va cac ban d6 cung cap cho ta nhtrng th6ng tin tin cay de kh6i phuc lai sy tien boa dja chat ciia khu vyc nghien ciru Hinh 12 chi mat cat dugc kh6i phye lai a vi tri thii so d6 nghien ciiu Mat cat co huong tryc giao voi tryc chinh ciia he thong dirt gay chinh Chiing t6i da sir dyng cac phep bien d6i va thuat toan de tinh toan sy bao mon va chieu day cua moi tap tram tich cho viec kh6i phye lai mat cat, nhien, khu6n kh6 bao cao nay, chiing t6i chua co dieu kien de cap mgt each chi tiet den viec tinh toan ma no se dugc de cap den sau mgt nghien ciiu rieng biet khae Chiing t6i chi gioi thieu ket qua kh6i phye lai sy tien boa kien tao qua cac thoi ky Pha tach gian chinh xay Eocen (?) - Oligocen voi t6c lang dgng d6ng tram tich cao cac dia hao kh6ng che boi cac diit gay chinh tir bat dau hinh be (Hinh 12c) Hinh 12b chi pha sau tach gian thoi ky Miocen gitra dac trung boi sy tai hoat dgng kien tao va be mat mong bj nh6 cao cyc bg voi sy phat trien cac he th6ng dirt gay nhanh Hinh 12a cho thay cau true hien cua cac tap tram tich bj pha buy boi v6 s6 cac diit gay sau trai qua nhieu pha boat dgng kien tao phirc tap 248 Qua trinh phat trign cSu true ciia phan BJc bl Song Hong trgn co sd minh giai tai lieu^ja^hgjj ^^.lv,l^ir1,^]^,^rMU^ãrMl?^,m.#ff^Ti^%^.llai?>^'r?^^^ 14 II IIHIi>tl)iằM^HNMH V K K -lcsiiliô R M H M N K R B H s a l t K « « i B « « t ( K M H l ) t R H M M N M n n ô H ã ( ( • • • R H B K K K l I K H I I K H M H M ô ô N ô M ã M H M I t M H I l R K x a K ã ã H ằ ô H B a i | M ô H ) C HKMKKHHIIOBMMi ã ã ã • a B < i l « ) i a H J | KVaiill K B M B K M K • • • • v a i i a j i z z K X B X H S k K K M I I K B H us "W • H V I t H H I t a B B a B ' K M B K » B B B K | t | | | C M I M K X H RN K M B ã ã ã ã ã ô ô ã « t B R a B R B B W K H I t K l l l i V b a l ) I M N R U R R R « * M > N H M B a r « B B « K a H | i x a K K B B X M B N I M K B M B B H s H N M M M a M M H I « M > « « a « K M I I l r l l B I I R « B B t m X A M i r K M N K H K B R K i r k M B H r S M f t R M B S K K i B R B C k i a K •,tt i a s a B B B a i H « « H K « a ^ « « k H H K H H R M K s a * M i i K H H x B x IB B B M B B H ^ N R B M t a v B B B ô ã* ^ ^ ^ ' • > : : * " X a a a a ô!*'ã-.- _ K B H K M B t a H M M M * «A K X R i T * li MJU % a tt R BII t i f a a K B l a a K MMMMBH V R H i i a a a a l B a a a a a a B R R v a i f H I B B a E B K B B • • M B a M y K M B R K K H H a i M » H M B N a a H ] I X K R R i A a ) i B a M B a « a x M < | i R M M K I K K K B a a a a a a a l B B a B H K M M & w B a a a « a a a H i i R i t X K « L i , » , H « N H H i f t i i i - ^ K R H a M H R h M m a a a n a « H Kamxx-KMMm Mm * K K M « a B K a M B X « B g A H K M • • • a M i i « a i i a i i a m ft w ; SCO > K M a f K K a K k • t l M X a H K H N a a H V l M R R R R R M a e Jm a a a a ] - J r; a a K H M t v a M M M M ' It H R V K It II K h - x a M a a x x > * a a a a a a t t < ) r a a « M a X - a a a a H K N i i M K H I I X B K B a K M v a i aC3 K a a B M s a n a B M K X H R K M R a a x x a a a a a H K R R R R K R M I «t N « M a ) i B K K a a a a a H H R M S B I K K a a v H a a a x a : • • a a a » x K « - x a * * a * » a » M K « M R a » i X a f i » » r t a a a a M K * B X B R x a w « M a a » B | ia*i a a « N R a a M K a i i a B B a a B B » R a M K i i H M « » B « M a M M B n CRTiRKMjrv hi • R K x a a x B a x B a x M B a M B R K K H a a M B a M B ^ K B a a M M a a K v a K a a a B i U IBM MKHMR N X H a a t t K B a a a M » » K x a « B a x a « M a M B a H a H « x ] „ , | , | g ^ I M B MK K K K K K K M i c v M a a a B « « x a i B K Z B B M t t K v M B ^ K M a a K B i t ^ n i i H v a a i i a s a M M : Ia a I : x a x a < | ) t X « R H M X H a « M t a > " n i | B M i t a N J l S a a a a a a a H K a M a a ô *cco I a s ã It X K V K K B a « a M « - a M « H B « H M P K M a B a B K B « R a K X M K B M R » H a a a ^ , • • N K M I txK B a « x x i t X M B x a a « B a a B H a a a H a R H N a M M a a « a i i B M R X M B x a a ^ I a a a x x K x a K K M • • • ^ • K K I l K M N K X B a « * B « M a a a x a a a a K » K « M B « a k a ' ' i a at u t v M B M iiH A « x H * ' j r f t c « a , r j r a a a M B i i H « M « s a - a a « * « * i « M ] t H I U a i | « K a I a a N N n K X R K K N X a B B B B S a a M B H K l t H a a a a a * aawvMMMM 7K5 a X N I1 a a I ' M M H a R K H K K K B l fcv»KMaBaBBBBaaaa«a8MHXkaa|4|[„K^,,l^ ^" J "IM I « a R H N N « M l l M a « M « a « a a a a « M a a a « a M a a B a B a R H K « H « B l i a a « a a a a M Hinh 12: Mat ck dia chan tren Hinh - Khoi phuc lai mat cSt cho a) Hien tai; b) Miocen trung; c) Oligocen - Miocen som (a, b, c theo thii ty tir tren xulng) Tuygn tap bao cao Hoi nghi KHCN "30 nam Phu Viet Nam: Co' hoi mdi, thach thuc mdi" 249 KET LUAN VA DE XUAT Tir nghien cuu cua minh, chiing t6i da rut dugc vai dieu ket luan nhu sau: - Cae diit gay chinh khu vyc nghien cim chu yeu phat trien theo phuang Tay Bae - D6ng Nam va kh6ng che phia D6ng va Tay cua be Song H6ng - Sy phat trien ciia cac diit gay v6 cimg phiic tap va bao g6m nhieu he th6ng diit gay nh6 Cac cau tao hoa duong, am dugc phat hien tren nhieu mat cat chi co che boat dgng kien tao cua be S6ng H6ng v6 ciing phiic tap - Cac tram tich Miocen bi u6n nep manh vai chieu day thay d6i co the quan sat ro tren nhieu mat cat dja chan - Duoi anh buong cua tai boat dgng kien tao, be mat mong bj nang len vi vay chieu day tram tich Oligocen thay d6i manh va co the bj bao mon a nhiing noi kh6i mong nh6 cao Nhimg nhan xet tren cho thay, khu vuc nghien cuu da trai qua mgt lich sir boat dgng kien tao co the tom tat nhu sau: - Pha tach gian chinh thai ky Eocen (?) - Oligocen ke tir be Song H6ng dugc hinh co lien quan vol djch trugt trai ciia diit gay S6ng H6ng - Pha sau tach gian thai ky Miocen, danh dau bai tai boat dgng kien tao Miocen giira, lam cho tram tich bj pha buy manh - Sy thay d6i buong djch trugt cua diit gay S6ng H6ng tir trai qua phai khoang 5,5 trieu nam truoc day co the nhan qua sy phat trien dirt gay Sau khu vyc nghien ciru co boat dgng kien tao kha binh 6n voi nhiing tram tich c6 the nam ngang va phan lop song song Nghien cuu cho ta mgt cai nhin t6ng quan ve sy phat trien dut gay be S6ng H6ng va giiip cho viec xay dyng mgt m6 hinh ly thuyet ve sy djch trugt ciia dirt gay S6ng H6ng anh huong ciia sy va cham mang An Do vao mang A - Au Hien chiing t6i dang kiem chimg m6 hinh bang phuong phap cac phan tir rieng biet (DEM) va se trinh bay ket qua mgt bao cao gan day TAI LIEU THAM KHAO Avouac J.P., Tapponier P., 1993 Kinematic model of active deformation in central Asia Geophysical Research Letters, Vol 20, N° 10, p 895 - 898 Dewey J.F et al., 1989 Tectonic evolution of the India/Eurasia collision zone Eclogae Geol Helv 82/3, p 717-734 Hall R., 1996 Reconstructing Cenozoic SE Asia In: Hall R., Blundell D.J (Eds) Tectonic Evolution of SE Asia Geol Soc Lond Spec Publ., 106, p 153 - 184 Hall, Robert, 1997b Cenozoic plate tectonic reconstructions of SE Asia In Fraser A J., Matthews S.J., Murphy R.W., eds., Petroleum Geology of Southeast Asia: Geological Society Special Publication, N^ 126, p 11 - 23 Huyen B.T.T, Yamada Y., Matsuoka T., 2003 Cenozoic tectonics of Southeast Asia (SE Asia) and its infiuence on structural styles in Vietnam Proceedings of the 250 Qua trinh phat trign cSu true ctia phhn Bde bg Song Hdng tren co sd minh giai tai lieu dja chSn International Workshop on Earth Science and Technology, Kyushu University, p 211 219 Le Pichon X., Foumier M., Jolivet L., 1992 Kinematics, topography, shortening, and extrusion in the India - Eurasia collision Tectonics 11 (6), p 1085 - 1098 Reports of Vietnam Petroleum Institute for Song Hong basin, 1992, 1999 Taylor B., Hayer D.E., 1980 The tectonic evolution of the South China basin In: Hayes D.E (ed.) The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands American Geophysical Union Monograph, 23, p 89 - 104 Taylor B., Hayer D.E., 1983 Origin and history of the South China basin In: Hayer D.E (ed.) The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands, Part American Geophysical Union Monograph, 27, p 23 - 56 ... phat trien cac cau tao dau trien vgng Cac ket qua minh giai Nham myc dich dua mgt cai nhin t6ng quan ve be trhm tich Song H6ng, chiing t6i tien hanh minh giai nhiing tap dia chan chinh dya tren co... Viec minh giai cac diit gay dugc tien hanh dya tren co so cac diem gioi ban, phan xa tryc tilp tir mat ciia cac dut gay hay sy thay d6i dja tang co the nhan thay dugc tren cac mat ck dja chan Minh. .. granites, red elastics Hinh 3: Cot dia tang tong hop ciia Bae be Song Hong (theo PetroVietnam) MINH GIAI DIA CHAN CHO B A C BE SONG HONG Cff Sff du" lieu Cac khao sat dja ch^t, dia vat ly da