THAM DO KHAI THAC D A U KHI ^ 3 ^ SI ^^ 93 DAC DIEM HINH THAL CO CHE D Q N G HOC CUA DOI DUT GAY TRUNG TAM MIEN VONG HA NOI VA SU" ANH H J O N G DEN QUA TRINH HINH THANH PHA HUY BAY CAU TRUC DAU KHI T[.]
THAM DO KHAI THAC D A U KHI SI ^^ 93 ^ 3^ D A C DIEM HINH THAL CO CHE D Q N G H O C C U A D O I DUT GAY TRUNG TAM MIEN VONG HA NOI V A SU" A N H H J O N G DEN QUA TRINH HINH THANH - PHA HUY BAY CAU TRUC DAU KHI TRONG CENOZOIC CN Hoang Hiiru Hiep, ThS Nguyen HCru Nam Cdng ty Ddu Sdng Hong Tom tat Ddi ddrt gay trung tam Mien vong Hd Noi gom dCtt gay Vinh Ninh, dvtt gay Thdi Binh va cdc dvtt gay bac cao nhm giCfa chung thuoc he thong dvtt gay Song Hong Day Id he thong pha huy kien tgo Idn, noi tieng tren the gidi gom bien dgng deo vd bien dgng gion vdi cdc cd che dpng hpc rat khdc Trong bdi bdo nay, nhdm tdc gid phdn tich doc diem hinh thdi, cd che dpng hpc cua ddi dvltgdy trung tam Mien vong Hd Noi, tvfdd chira vai trd, si/dnh hi/dng den qud trinh hinh thdnh - pha huy cdc kieu cdu tgo nghjch ddo chda ddu Tdkhda: Dac diem hinh thdi, dgng hgc, ddt gay Vinh Ninh, ddt gay Thdi Binh, trung tam t\Aien vong Hd Noi, Cenozoic Gidi thieu He thdng dOt gay Sdng Hdng la mot he thdng dOt gay trapt bang Idn bat dau t d cao nguyen Tay Tang keo dai qua vjnh Bac Bp tdi Natuna (Indonesia) vdi tong chieu dai hPn 2.000km Trong tdng khdng gian va giai doan khac nhau, he thdng dOt gay phat trien d nhdng dp sau rat khac vdi cac che dp xiet trapt ep nen hay xiet trapt tach gian t d dd tao cac cau true cd dac trang rieng [6] Cau true pull-apart (be keo tach Sdng Hdng) la mot phan doan dau khf da xac djnh dapc sa keo dai cua cac cau true nang Khoai Chau -Tien Hai va Kien Xapng Mot loat gieng khoan tham dd tren cae dai cau true da ddpc trien khai nhif; 103-T-G-1X, 103-T-H-1X, 102-CQ-1X, 102-HD-1X, 102-TBIX, 103-HAL-1X, 103-DL-1X Ket qua da phat hien diTOc md khf Thai Binh (Ld 102) va cum md Hdng Long (Ld 103107) (Hlnh 1) Dieu cho thay cd sd lien he giCfa cac cau true chda dau vdi ddi ddt gay trung tam Mien vdng Ha Ndi va can dapc lam sang td cau true dac biet va la be tram tfch Cenozoic Idn nhat tren Tfnh chat, dac diem hinh thai cua ddi duTt gay trung them luc dja Viet Nam gom phan tren dat lien vdi ten gpi tam Mien vong Ha Noi Mien vdng Ha Ndi va phan ngoai khoi vjnh Bac Bd bao gom t d cac Ld 102 den Ld 121 Ddi dot gay trung tam Mien vdng Ha Ndi gom dijft gay chfnh la Vinh Ninh va Thai Binh cung vdi cac dut gay Ddi dOt gay trung tam Mien vdng Ha Ndi la he thdng gom cae dOt gay Vinh Ninh, Thai Binh va cac dOt gay nam gida hai ddt gay (nhaTien Hai, Kien Xaong, cac dOt gay bac cao khac ) tao he thdng ddt gay kieu thuan hadng - ngapc hadng (synthetic - antithetic faults) rat dac trdng Ket qua cdng tac tim kiem tham dd dau khf giai doan 1960 - 1975 cho thay ddi dOt gay Vinh Ninh va Thai Binh khdng che cac cau true dai nang cua Mien vdng Ha Ndi (dai nang Khoai Chau Tien Hai va dai nang Kien Xaong) [9] Tren co sd dd, cac tuyen dja chan va gieng khoan da dapc thiet ke de tham dd dau khf tren cac dai nang Ket qua da phat hien dapc md khf Tien Hai C tai dai nang Khoai Chau-Tien Hai va daa vao khai thac t d nam 1981 den (Hlnh 1) Ddi dut gay trung tam Mien vdng Ha Ndi bj khdng che bdi he thdng ddt gay Sdng Hdng, cu the la ddt gay Sdng Chay va ddt gay Sdng Ld/Trang Kenh Cdng tac tim kiem, tham dd ngoai khoi vjnh Bac Bd cua Tap doan Dau khf Quoc gia Viet Nam va cac nha thau 26 DAU KHi-so 9/2014 Hinh Bdn cdu true vd phdn bd cdc dgng bay khu vac Miin vong Hd Noi vd Idn can (thdnh lap tren co sd bdn dia chdt t^ li 1/200.000 [11] vd tdi liiu cdng bo cua Petrovietnam [5] - cd chinh sH PETROVIETNAM bac cao nam gida chung.Trong dd, cd hai ddt gay bac cao Tam Da (huyen Son Daong -Tuyen Quang) la ranh gidi kien quan trpng la Kien Xapng va Tien Hai gidi han dai nang tao gida cac tao bien chat tuoi Proterozoic muon - Kien Xaong va dai nang Tien Hai vdi nep Idm Phdpng Ngai Cambrian sdm he tang Thac Ba Dac biet, tdTam Da den thj tran Lap Thach (huyen Lap Thach 2.1 Ddt gay Vinh Ninh Vinh Phuc) phat then cac tao milonite cd ngudn gdc t d granite phdc Tren binh cau true hien dai cd the xac djnh ddpc he Sdng Chay (aD^sc,).Ta An Hda (huyen Lap Thach) theo ddt gay Vinh Ninh tach t d ddt gay Sdng Chay tai khu vdc hadng Ddng Nam dOt gay Vinh Ninh keo dai chay qua khu Thac Ba -Yen Bai vdi sdxuat hien cua tram tfch Neogene he vdc HdTay (Ha Ndi) va vdon vjnh Bac Bp, ddt gay chu yeu tang Phan Laong [11] (theo ban dja chat ty le 1/200.000 phat trien tang tram tfch Neogene va bj che phu bdi td Tuyen Quang) TdThac Ba (huyen Yen Binh -Yen Bai) den tram tfch DeTd Nha vay, doan qua Ha Ndi doc theo Sdng Hdng la ddt gay Vinh Ninh, cdn ddt gay Sdng Hdng thdc sa A 50 A' NCii SUng lai chay dpc theo rla Bac cua day nui Chuc SPn khu vac huyen Lap Thach khoang each gida dOt gay NLII Th6t Sdng Chay va ddt gay VTnh Ninh chi la 5km, mat cat AA' N,p(vA phaong Tay Nam - Ddng Bac qua xa Hai Ldu (Lap Thach) ^ Q tV Iv Q\ l\ Bk'm "0® /i f /I cd the thay dapc cau true dac trang (Hlnh 2) Ddri milonite 12km / • W DOt gay Sdng Chay va ddt gay Vinh Ninh keo dai ve k phfa Ddng Nam tao mot thung lung d gida ddpc phu /s bdi tang tram tfch De Td Gida thung lung De Td xuat /'S hien mot sd dai nui hep chay dai theo phaong Tay Bac Hinh Mat cdt dia chdt phaang Tdy Nam - Ddng Bac qua khu vacDdng Nam vdi phan la cac tap tram tfch cuoi ket, cat Hdi Lau - Lap Thgch ket hat thd tuoi Neogene sdm thudc he tang Phan Laong, noi cao nhat cua dai nui Neogene dat tdi dp cao 340m (nui Thet) Td nhdng so lieu ve dja chat va dja hlnh, cd the khang djnh Cenozoic ddt gay Vinh Ninh da tdng hoat dpng nha mot ddt gay nghjch lam nang trdi cac tap tram tfch cd san len tdi dp cao vai tram met nhd hien tai Ddng Bac ddt gay Vinh Ninh d khu vac la nui Sang, tren dd phat trien cac tao milonite cd nguon gdc t d granite (Hlnh 3) Quan sat mot vai vj trf cua nui Sang cd the thay rd cac mat trapt, vet xadc the hien qua trinh trdpt bang trai vdi phdPng trapt Tay Bac - Ddng Nam va gdc pitch (gdc cua vet xddc so vdi mat phang nam ngang) gan Hinh Thdnh tgo minolite ngudn gdc tddd granite khu vac nui nhd bang (Hlnh 4) Sdng the hien chuyen dgng tracft bdng trdi cua ddt gay Vinh Ninh Ve phfa Ddng Nam Mien vdng Ha Ndi, dien phat trien cua tram tfch Pliocene - De Td Idn, che phu cac tram tfch Neogene Theo tai lieu dja chan va cac gieng khoan (5.400km tuyen dja chan, tren 80 gieng khoan), cac tram tfch Paleogene - Neogene d day ddpc phan chia cac he tang Phu Tien (E^), Dinh Cao (E3), Phong Chau (N/), Phu Cd (N,2) va Tien Hdng (N,^) He tang Vinh Bao (N^) dapc tao dieu kien kien tao binh on nam phu bat chinh hpp tren he tang Tien Hdng Ranh gidi dddi cua cac he tang tdong dng vdi cac mat am hpc: Mat mdng (SbO) 52 trieu nam trade, Sbl - 32 trieu nam trade, Sb2 - 23 trieu nam trade, Sb3 16 trieu nam trade, Sb4 - 11 trieu nam Hinh VetxUdc delgi tren mat tragt the hien qud trinh tragi bdng trade va Sb5 - trieu nam trade Day cua he tang Vinh Bao trdi cua ddt gay Vinh Ninh tai khu vac nui Sdng DAU KHi-SO 9/2014 27 THAM DO KHAI THAC D A U KHI dng vdi mat Sb5 - trieu nam trade Trong Sbl, Sb2 va tram tfch thudc canh Tay Nam da ddpc nang len vao cuoi Sb5 la cac mat bao mdn, bat chinh hpp Idn cd the quan sat Miocene Do dd, trddc pha nghjch dao xay ra, ranh gidi ddpc d nhieu khu vdc thudc Mien vdng Ha Ndi cung nhd dddi cua he tang Phong Chau d canh Tay Nam se nam b ngoai khoi vjnh Bac Bp vj trf thap hon so vdi canh Ddng Bac Dieu chdng t6 Tren mat eat dja chan BB'phaong Tay Nam -Ddng Bac trade chuyen dpng nghjch ddt gay Vinh Ninh la mot ddt gay thuan ed bien dp djch chuyen Idn qua gieng khoan 104 (Hinh 5) cd the thay rd tfnh chat hoat Ket hpp tai lieu gieng khoan va tai lieu dja chan, ddng da pha cua ddt gay Vinh Ninh: Dda vao cae ranh gidi dddi cua cac he tang Tien Hdng (Sb4) va PhCi Cd (Sb3) gida hai ben canh cua ddt gay, cd the khang djnh tfnh chat nghjch cua ddt gay Vinh Ninh, cac tap tram tich thudc canh Tay Nam ddpc nang len pha nghjch dao kien tao Td tren mat cat xac djnh pha nghjch cua ddt gay hoat dpng vao giai doan cuoi Miocene nhdm tac gia tfnh toan bien dp djch chuyen ddng cua ddt gay tdng pha hoat dpng Ket qua cho thay bien dp djch chuyen pha nghjch dao cuoi Miocene thay doi manh theo khdng gian So sanh ranh gidi cac phu he tang Tien Hdng va Phu Cd d canh tree va canh nam dpc ddt gay Vinh Ninh theo hddng tdTay Bac xudng Ddng Nam cho thay: bien dp djch chuyen cua ddt gay pha nghjch tang dan t d gieng 107 (bien Dda vao ranh gidi dddi cua he tang Phong Chau (Sb2 dp khoang 550m) den khu vdc cae gieng 103,65, 74,77 dadng mau hdng) da dapc chuan hda t d tai lieu gieng (bien dp khoang 1.200 - 1.350m) rdi lai giam dan xuong khoan cd the thay tren binh hien tai ranh gidi d khu vdc gieng 106 (bien dp 800m), gieng 79 (bien canh Tay Nam thap hon so vdi canh Ddng Bac, cac tap khoang 550m) va ngoai khu vac Ld 102 thi bien djch chuyen khdng dang ke (Bang 1) Tren mat eat BB' (Hlnh 5), vj trf hien tai cua day tang Phong Chau (dddng mau hdng) d canh Tay Nam dift gay VTnh Ninh thap hon so vdi canh Ddng Bac khoang 400ms tdOng dng vdi tren 550m (tfnh theo van toe I6p tren mat cat dja chan) Trong day tang Tien Hi/ng (dddng mau xanh la cay) d canh Tay Nam lai cao hdn so vdi canh Ddng Bac khoang 650ms tdOng dng vdi khoang 800m (tfnh theo van tdc Idp tren mat cat dia chan) Do do, tai vj trf cua mat cat BB' cd the tfnh diioc Hinh Mat cdt dja chdn BB' the hien tinh chdt hogt ddng da phabien dp djch chuyen ddng cua ddt gay Vinh Ninh pha thuan khoang 1.350m cua ddt gay Vinh Ninh Bang Chieu sdu ranh gidi cdc phu hi tdng Tiin Hang vd Phu Ca2 dphdn trin vd dadi ddt gay Vinh Ninh (theo tdi lieu cua Petrovietnam) Chleu sau gieng Dja t a n g ^'*^" |, jKy He Thong ^.-^ z lOCENE NOZOIC EOCENE tang •^ Gieng 107 Gieng 103 Gieng (2.600m) (3.000m) (2.060m) Phu ! Tren he duft ^ • t a n g gay Dudi ddt gay Tren dut gay DUdi ddt gay 505 1.850 864 2.060 1.259 395 1.163 1.380 II