Kết quả bước đầu nghiên cứu tốc độ lắng đọng và tuổi trầm tích hiện đại vùng cửa sông bạch đằng bằng phương pháp đồng vị phóng xạ 210pb và137cs

V I~N B A N LA M K H O A H Q C V IEN D IA CH A T •• vA C O N G N G H ~ V IeT N A M vA D IA V A T LV B IEN •• V IETN A M A C A D EM Y O F SC IEN C E A N D TEC H N O LO G Y IN STITU TE O F M A R IN E G EO LO G Y A N D G EO PH Y SIC S TU Y E T-PB ' CAOKHO H Q I N G H f K H O A H Q C B fA clIA T B IEN ToA N HA NQI - ~ OC • ouoc LA N TH U H A l LO N G , 10-12/10/2013 PR O C EED IN G S TH E SECO N D N A TIO N A L SCIEN TIFIC CO N FEREN CE O N M A RIN E G EO LO G Y H A N O I-H A LO N G , 10-12 O CTO BER, 2013 l 14 Trin A nh Tu~n, Phung V an Phach V ien dful chirng cir v~ dia m ao h6 tro 198 xac dinh ranh gioi vo luc dia - dai dirong tren B iSn D ong V iet N am 15 Le D inh N am , Le Phuong, Trin D uc A n, N guyin X uan Lvi, Trin Th~ Ti~p, Ph an D ong A nh Tuan, Trin va Ph a, H oang Y ~n, D uong Le 207 Tu~n N goc, M Q t s6 d?c diSm dia m ao khu V \ICTruong Sa va Tir C hinh - V iing M ay 16 B ili V an V U 'Q 'Ilg,Trin D uc Th~nh, D ~ng H oai N hon D ?c diSm hinh thai dia 219 hinh ran san ho quan dao Truong Sa 17 Trin X uan A nh Tu~n, Lvi, N guyin Th~ Ti~p, Ph an D ong Ph a, Le D inh N am , Trin V ii Le Phuong, Trin H oang Y ~n, Pham 229 V i~t H A ng, D uong Tu~n N goc, D ?c diem dia hinh dia m ao day bien N am Trung B Q 18 V ii V an Phai, D uong Tu~n N goc, LU 'u Thanh C N hfm g bang chirng 243 dia m ao v~ S\I thay d6i m ire m roc bien tren dai be bien N am B Q giai dean tir H olocen gifra d€n 19 V O Thjnh, Phan D ong Pha, N guyin Tu~n, Le D inh N am , Trin X uan X uan H uyen, Lvi, Trin V ii V an Ph ai, Tang Phuc H oang Y ~n, va 251 Le Phuong, D uong Tu~n N goc, C ac kiSu 00 bien khu V \ICPhu Y en - K hanh H oa va vfuI d~ du bao xu th€ bien dQ ng bo bien b6i canh m \IC m roc bien dang 20 Pham B a Trung D ac diem dia hinh day va trfun tich tfuIg m at vung bien ven 260 bo tinh B inh D inh, 21 N guyin D ang Tuc, Phan Trong Trinh, B ili V an Thom , N guyin V an 271 H U 'O ng, N go V an Liem , V ~ cac them biSn va tu6i san he doc bo biSn K hanh H oa - B inh Thuan 22 V ii D uy V inh, B ui V an V U 'Q 'D g.A nh huang cua m Q t s6 y€u t6 nrong hai 285 van d€n bien dQ ng dia hinh day vung ven bo chau th6 Song H 6ng 23 V ii V an Phai, D uong Tu~n N gQ c, LU 'u Thanh If thong D inh N am N ghien ciru dia m ao phuc vu quan 24 B ui V an V U 'Q 'Ilg,Liu Zhi Fei, Trin H ub, Tuo Shouting, D uc Th~nh, D ~ng H oai N hon, N guyin D inh V an H uy, N guyin Trung, D inh K hang V ii Le Phuong, Le 297 nhat doi bo bien Trin D inh Lan, C hi-A n V an Q uan, N guyin 306 D ic V ~, K €t qua biroc dau nghien ciru t6c dQ lfutg dong va tu6i tram tich hien dai vung cira song B ach D fu1g bang phirong phap d6ng vi ph6ng xa 210pb va 137C S 25 N guyin Ti~n H ai, Ivanova tram tich Lk.D A 26 H oang a khu Trung Y e.D , N guyin H tru Cu D ?c diem m oi tnrong V \IC cira D a R ang, Tuy H oa (Phu Y en) qua t~p m §:u D u, Tim Jennerjahn, A ndreas K unzm ann 316 16 khoan Tac dQ ng nguon 327 v~t ch~t song len lang dong trfun tich va y€u t6 sinh dia h6a vung bien ven bo vinh N Trang - K hanh H oa 27 N guyin H oang Trung Thanh, Phung V an Long, Pham V an Phach, Le D uc A nh, Pham Tu~n A nh, 342 Q uac H i~p D anh gia anh huang phan toa phu sa cua song M e C ong len them I\lC dia k€ c~ bang ham hrong t6ng cacbon htru co (TO C ) va cacbonat tram tich 28 Phi Truong Thanh, Trin H a, N guyin Th] D ung, Trin lira bun, Tu~n D iing, N guy~n Q uang M inh, N guyin Th] H Th] H A ng M inh, Ton V an Son T6ng quan v~ nui 354 H6i nghi Khoa hoc Dia chdt biin toan quoc ldn tM II zyxwvu KET QuA BUOC DAu NGHIEN ciru TOC DQ LANG VA TUOI TRAM ZYXWVUTSRQPONMLKJIHGFEDCBA 'r t c n HI¥N D~I vUNG CUA SONG B~CH PHUONG PHAp DONG IBili Van VU'c;mg, 2Liu Zhi Fei, ITdn VI PHONG Du'c Th~nh, ~ ITdn DQNG DANG BANG 210Pb va 137Cs Dinh Lan, 2Chi-An Hub, ID~ng Hoai Nhon, INguy~n Van Quan, INguy~n D~c V~, 2Tuo Shouting, IDinh Van Huy, INguy~n Dinh Khang "Vien Tai nguyen va Moi truong bidn - VAST 7ruc'mg Dai hoc D6ng tt ThuongLKJIHGFEDCBA H a i, Trung Qu6c E-mail: vuongbv@imer.ac.vn TOM TAT: Vimg cua song Bach DJng la mot cua song hinh phlu 11m va quan thir Nam (sau cua song D6ng Nai), nai co cang Hai Phong va cang nutrc Lach SQU & H uyen tuong lai Vimg cua song chica dung tai nguyen thien nhien da dang va phong Vi¢t phu, lien quan ddn din h¢ thong lach tri€u va cac h¢ sinh thai nhu rung ngtjp mdn, bdi trieu v v Trdm tich va dia hinh (fling dong tram tich, sa b6i luong lach) vimg cua song bidn d6i manh co anh huong ddn gia tri tai nguyen va cac hoat d6ng kinh kit qua nghien CUu d dgc biet la cang bidn Bai bao trinh bay buac dau vi t6c d6 lling dong, tu6i tram tich hien dai cua tram tich vung cua song Bach DJng T6c d6 !&ng dong tram tich nhdn duac tir mat clit 210 Pb va 137CS bien d6ng tir 0,69-0,97 cm/ndm, kh6i IU(1ngtram tich tich tu tir 0,5198 ddn 0,8045 (g.cm- yr- l) 210 Pb duac sit dung cho tinh toan tu6i tram tich hien dai vong 100 ndm, 137CS dung dd 2l xac nhdn d6c ldp kdt qua tu6i tram tich nhdn duac tir OPb T V ' KHOA: T6c dQ l~ng dong, tu6i, Bach Dang, 210Pb, 137CS D~TvANDE Tang quan vin d~ nghien cuu Vao nam 1963, Goldberg IAn dAu tien d~ xuat v~ sir mAt thang bang gifra 210Pb va 226Ra co th~ phuc vu xac dinh tu6i trAm tich hien dai, Ciing nam do, ong da ap dung cong phirong phap phong xa 210Pb co ban chu ky phan la 22 nam d~ xac dinh tu6i tram tich cua cac tang bang a Greenland [14] D€n nay, phirong phap dll duoc ap dung va ph6 bien rong rai d~ dinh tu6i, t6c dQ l~ng dong trAm tich cho cac thuy V\fC: h6 [17], [36], bi~n [18], [29] va dAm pha [2] Ben canh 137CSciing duoc sir dung d6ng hanh, kiem chirng dQc l~p so voi 210Pb d~ tinh to an tuoi, t6c dQ lang dQng trAm tich K€t qua tinh toan v~ tu6i, t6c d9 l~ng dong tram tich la C (J sa quan nghien ciru anh huang cua qua trinh tram tich den qua trinh xoi lo; b6i tu, gia tang dQ due, C (J ch~ v~n chuyen tram tich tic nguon d~n b6n [6], [10], [11] va cac tac dQng toi cac h~ sinh thai, vi du nhu h~ sinh thai co bi~n va ran san ho 306 tu« ban Dja ehdt va Tai nguyen, Khodng san biin H9i nghi Khoa hoc Dia chat bidn toan qu6e tdn thU II Vung cira song Bach D~ng (VCSBD) la mot cira song hinh ph@u IOn va quan thir Vi~t Nam (sau cira song D6ng Nai), noi co cang Hai Phong va cangZYXWVUTSRQPONMLKJIHGFEDCBA m r o c sau Lach Huyen nrong lai Day la vung cira song chira dung tai nguyen thien nhien da dang va phong phu lien quan den h~ thong lach tri~u va cac h~ sinh thai nhu nrng ngap man, bai trieu v.v Trftm tich va dia hinh va (lang dong trftm tich, sa b6i luong lach) vung cira song bien d6i manh co anh huang den gia tri tai nguyen va cac hoat dong kinh te d?c biet la cang bien, d6 thu hut m6i quan tam cua cac nha khoa hoc nhir: tien hoa chau th6, dong lire hoc, trftm tich hoc, dia mao hoc, v~n chuyen trftm tich, Nghien ciru v~ tu6i, t6c dQ l~ng dong trftm tich hien dai a vung cira song v~n chira duoc quan tam Bai viet cung dp dfr lieu, thao luan v~ tu6i va t6c dQ I~ng dong tram tich hien dai vung cira song Bach D~ng dira tren tinh toan nang luong phong xa cua 210Pb va 137Cs elOPb, 137CsradionucIides) tai mot s6 cQt khoan 6ng ph6ng trftm tich tftng mat TAngMLKJIHGFEDCBA q u a n v~ di~u ki~n t v nhien vimg cua song Bach J)~ng V ung cira song co c~u true mra kin, co quan dao Cat Ba chan phia dong bac, ban dao D6 San chan phia tay nam va co h~ dao cat Phu Long, Cat Ba, Dinh Vii chan ph fa bien a dong nam Cac nhanh song chinh tren vung cira song la Yen Lap, Bach D~ng, C~m va Lach Tray (hinh 1) Dia hinh VCSBD da dang va phirc tap, g6m nhi~u kieu, dang dia hinh co nguon g6c khac va co th~ duoc chia nhorn: Dia hinh d6i va nui thap, d6ng bang khong ngap trieu, d6ng bang ngap tri~u tv nhien va dia hinh bo ngftm - luong lach ngap mroc thirong xuyen [32] H ~ th6ng lach trieu phat tri~n day d?c va thuoc hai nhom Nhorn thir nh~t phat tri~n ke thira nr nhfmg long song cii diroc mo rong va dao sau long nho xam nhap cua dong tri~u b~ mat va day (Lach Huyen, Nam Trieu, Cai Trap v.v.) Chung rong toi 2-3 km, sau toi 10-15 m va keo ngam phia bi~n chuc km Chung bao va chia cac khu bai trieu cac dao biet I~p, rong toi chuc krrr' Nhom thir hai g6m nhieu cap, hinh heat dong cua dong trieu tftng mat, Chung phan dt cac dao bai trieu nhieu manh khong tach roi Cac bai trieu cao chiem 70% dien tich, dQ cao tuyet d6i 0-1 m [32] Day la vung co che dQ nhat trieu di~n hinh voi hftu h~t s6 thang la nh~t trieu, dQ IOn tri~u cue dai m, t6c dQ dong trieu trung binh 30-50 cm/s, cue dai toi cm/s Dong tri~u thuan nghich, eIIip tri~u r~t dep Kh6i mroc VCSBD -1 co ban IQ'va IQ'nhat vao mua rmra, lo va IQ'man vao mua kho Dong chay co phan dong tri~u quyet dinh, nen co tinh thuan nghich ngay, phu thuoc vao dia hinh bo, huong bo, luong lach va cira song Dong chay manh vao cac thang 6, 7, 12, 1, y~u vao cac thang 3, 4, 8, va manh nhat mire mroc dao dong len-xuong ngang qua mire trieu trung binh T6c dQ dong khoang r~t rQng tir 0,1-1,8 m/s, trung binh 10-30 cm/s T6c dQ dong chay xuong IOn hon dong chay len: Tai cira Nam Trieu, t6c dQ dong chay xuong cue dai 90 cm/s, t6c dQ len cue dai la 60 cm/s Do anh huang cua dia hinh, song bi~n n6i chung O,75m, tnr nhfmg dip bao, tftn xu~t lang s6ng dat khoang tu« ban Dia chat khong Ian dQ, cao trung 20% Trong binh hftu h~t cac thang, va Tai nguyen,LKJIHGFEDCBA K h o d n g san biin zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 307 H(Ji nghi Khoa h9C Dia chdt biin toan quoc ldn thii II zyxwv dQ cao song Ion nhat thuong 2-3 m, song bao dat 4-5 m, C\l'C dl;ll'5,6 m Vao mua dong, tir thang d~n thang nam sau, song co dQ cao trung binh tir 0,5-0,75 m, thinh hanh huang dong voi tan xuat 34% va dong bac voi tan xuat 14% Vao mua he, tir thang d~n thang 8, v c i tan x u s t 27% va dQ cao song trung binh 0,7-0,9 m, song thinh hanh huang dong nam ZYXWVUTSRQPONMLKJIHG huang nam voi tan xuat 22% Vao cac thang chuyen tiep va 10, song huang dong va dong nam iru the I TAl LI~U vA PHUONG PHAp NGHIEN CUu 1.1 Tili Ii~u ° Bai viSt sir dung cQt khoan voi mil hieu HP08 va HP LKJIHGFEDCBA a dQ sau Ian hrot la 24 m va 10m so voi m hai d6 (HD) ChiSu dai cQt khoan HP08 la 65 em va HP 10 la 90 em Hai cQt khoan diroc thu chuyen khao sat chung g ifr a Vien Tai nguyen va Moi tnrong bien (IMER), Vi~t Nam va Phong thi nghiem Trong di~m Quoc gia Dia chftt bi~n (SKLMG), Dai hoc Tongji, Thuong Hai, Trung Quoc thang nam 2011 (hinh 1) ~-== ===~~~~~~r.nnr~~~ ~~~~rr~7>rJ~~~'~ 00· C H U G IA I 00" -sDuong V i tr i c o t o km @ sou d6ng (m ) khoan 10 ,/ ","s- ) 40' ~~ V.;,.secBd 107° 107°00· E Hinh 1: Sa a vung cua song Bach DJng va vi tri lJ khoan HP08 O'E va HP 10 1.2 Phuong phap 12.1 Phtin tich phong X{l bang tia phJ gama Theo dQ sau, cQt khoan dircc chia cac mfiu, m6i mfiu img voi cm S6 mfiu duoc phan tich 210Pb va 137Cs b~ng tia ph6 gama (Analysis of radionuc1ides by y 308 tu« ban Dia chat va Tai nguyen, Khodng sdn biin H9i nghi Khoa h9C Dia chdt biin toan qu6c ldn thu II spectrometry), theo tieu chuAn 327 va 375 [30] cua Co quan Nang hrong Nguyen tir Quoc t~ (IAEA), s6 m&u d~m tren may GMX Thai gian d~m m&u dao dl)ng nr vai gio d~n vai tai Vi~n Khoa hoc Trai Dit, Vi~n Han lam Sinica, Dai B~c, Dai Loan 1.2.2 Phuong phdp xdc dinlt tac d~ !ting d!Jng tram tich T6c d9 l~ng dong trim 137CSdutheo d9 sau (excess tich (cm.yr') 210-Pb hay 210Pbex, excess tich 137 -CSdu xam nhap vao trim may dien nguyen duoc tinh toan tir d6ng vi phong tich cac 137-Cs hay 137CSex)trong lap trim VI,1 tir [6], [14], [15], [21], [28] Trong xa 210Pb va thir vii hat nhan va sir c6 nha nghien diroc phan tich 137Cs (voi thai gian d~m dai) va liy nam ciru cac m&u trim tich 1950 la thai gian diu tien xuit hien 137CStren vung bien [6], [10], [11] T6c dl) l~ng dong trim tich tinh theo t6c dl) phan cua 137Cs ky hieu la SCs-137tinh theoZYXWVUTSRQPONMLKJIHGFEDCBA c c n g thirc: SCs-137=Z/(T o -1950) Trong Z, la 137Cs sir xam nhap theo dl) sau, To la thai diem thu m&u T6c d9 l~ng dong trim tich tinh theo t6c d9 phan cua 210Pb ky hieu la SPb-210diroc tinh theo cong thirc SPb-210= - A 1m, voi "Ala h~ng s6 phan cua 210Pb (0.03114y-I) 1.2.3 Kllai luirng tram ticb tich tl} Kh6i hrong l~ng dong 210Pbdu tai dl) sau z bit trim tich/don ky cua lap trim vi dien tich (g crniyr') duoc tinh tir theo tich eIOPbxs(z») [3]: Ln21OPbxs(z)-Ln210Pbxs(o)=(- A210m-I)W Trong do: Dan vi kh6i luong tich tu trim tich diroc tinh bang kh6i hrong trim tich tich tu kho, co don vi tinh (g.crn") w la quan h~ vo'i thai gian lang dong trim duoc di€n ta bang cong thirc t=W.fl (f la hru luong tich tu trim tich tich va g.cmi.yr') In210Pbxs(z)co d6 thi ngiroc voi kh6i luong tich tu tren mot don vi dien tich; w: k~t qua cua mat c~t 210Pb la tuyen tinh va goc d6c la: -"A21ofl 12.4 Mo hlnh tinh tugi tram tich SiI dung 210Pb d~ xac dinh tu6i trim tich la mot phuong phap ph6 bi~n va quan hien Dua vao d6ng vi phong xa cua 210Pb, co th~ xac dinh diroc tu6i trim hien dai vong 150 nam Trong trim tich t6n tai loai 210Pb: "supported san xuit tai ch6 boi qua trinh phan cua 226Ra va excess quyen Y nghia d9 phong xa (activity) tich 210Pb" diroc 210PbelOPbex) nhan diroc tir cua 210Pb pharr b6 theo d9 sau nhan duoc rieng qua trinh phan theo lu~t ham s6 mii (hoac tuyen tinh n~u chung ta ve sa d6 logarit s6 tu nhien) Tuy nhien gia tri n~n phu thuoc hoac l~ng dong trim tri xac dinh hoacbien tich va 210Pb phan b6 d~n vi d6i qua thai gian Do vay, hrong 210Pbex bang hrong 210Pb t6ng tnr di luong 210Pb diroc san xuat tai ch6 Co me hinh tinh toan cho 210Pb d~ xac dinh tu6i trim hi: CRS (Constant Rate of Supply) va CIC (Constant Initial tich diroc dung ph6 bien Concentration) [14] va tiep tuc duoc phat trien boi [25] Tu6i trim tich diroc tinh bang me hinh CRS (constant 210Pb supply) rate of [25]: t=l/s va In {A (O)IA (x)} t u « ponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ban Dia chdl Tal nguyen, K h o a n g san biin zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 309 H9i nghi Khoa h9C Dia chat biin toan qu6c tdn thu 11 Trong do: A(O) thS hien hrong 210Pb du tren m~t tram tich; A(x) thS hien 210Pb dir tai dQ sau (x); A la hang s6 phan cua 210Pb (0.03114i1); t la thai gian l~ng dong tr~m tich (tuci, nam) SU dung 137CSdS kiem tra dQc l~p voi nam 1950 la thai gian b~t d~u xu~t hien 137CS tram tich thuy V\l"C II.ZYXWVUTSRQPONMLKJIHGFEDCBA K E T Q u A v A T H A o LU~N 11.1 K~t qua T6c dQ va khoi hrong tich tu tram tich duoc xac dinh tir phong xa 210Pb va 137CScho d6ng T6c dQ lang dong tram tich tai vi tri HP08 tir 0,82 cm/nam dSn 0,97 2 cm/nam, kh6i hrong tich tu/l cm la 0,8045 glcm /nam va tuong irng tai cQt khoan HPI0 la 0,69 dSn 0,75 crn/nam va 0,5198 glcm /nam (bang 1) gia tri nrong Bang 1: T6c tJ (J tcing dong trdm tich (em/nom); kh6i lu a n g tich t1;-l/di¢n tich g/cm2/niim) Kh8i hreng tich T8c dQ ling d(}ng tr~m tich (cm/nam) tir dAng vi phong CQt khoan t\l/di~n tich x~ 210 (g/Cm2/nam) 137CS Pb HP08 0,82 0,97 0,8045 HPlO 0,69 0,75 0,5198 V oi vi tri CQt khoan, can cu phan tich phong xa, tu6i tr~m tich cho cQt khoan duoc xac dinh tir nam 1910 dSn 2011, khoang 100 nam (hinh 2) 11.2 Thao lu~n IL2.J.D{ic iliim liing dong tram tich VCSBD ° Tir kSt qua tinh toan t6c dQ tram tich cua cQt khoan HP08 va HP cho thay: t6c dQ l~ng dong trAm tich tai VCSBD tang dAn theo huang biSn: Tai cQt khoan HPI0, t6c dQ l~ng dong trung binh tinh theo phuong thing dirng nr 0,69 dSn 0,75 cm/narn va 0,5198 glcm /nam, vong 100 nam (nr nam 1910 dSn nam 2011) Tai vi tri cot khoan HP08 dQ sau 24 m/OmHD co t6c dQ i1lng dong tram tich trung binh theo phuong thing dirng tir 0,82 dSn 0,97 cm/nam, kh6i 2 hrong tich tu/I cm la 0,8045 glcm /nam, vong 66 nam (bang 1, hinh 2) KSt qua tren r~t phu hop voi d~c diem hinh thai - dQng lire va phan b6 tram tich tai khu bo hien dai: Hai CQt khoan m/OmHD) HP08 (0 dQ sau 24 m/OmHD) va HPI0 (0 dQ sau 10 thuoc phu doi song bien dang cua doi suon bo ngam va doi song pha huy [12], [22] Ben canh do, tai d c i heat dQng cua cac ySu t6 dong luc: Song, dong chay t6ng hop (thuy trieu, anh huang chay ven bo, dong chay song) 6n dinh theo mua cua cac ySu t6 thai tiSt b~t thuong nam, khong chiu (bao), va heat dQng cua cac ySu t6 dong lire cang 6n dinh.khi dQ sau khu bo cang tang len V6i d~c diSm nay, nen su phan b6, lang 310LKJIHGFEDCBA cMt va t u « ponmlkjihgfedcbaZYXWVUTSRQPONM ban D ia T a i nguyen, K h o d n g san biin H(Ji nghi Khoa hoc Dia eMt biin toan qu6e idn thU II zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA dong tram tfch nrong d6i 6n dinh theo khong gian va thai gian Tuy nhien, dieu quan hon ca la tai vi tri cQt mftu HP8, anh huang phu sa cua h~ thong Song Hfmg d~n vung ria ngoai cua VCSBD Ian hon.MLKJIHGFEDCBA C ore H P 08 2011 2005 " " P b ( d p m /g ) m C s ( d p m /g ) ZYXWVUTSRQPONMLKJIHGFEDCBA C ore H P 10 0.1 0.20.1 I 10 1995 15 1990 20 1985 25 1980 30 1975 35 I ~~ + 2000 10 ~ + ~ ++ + 2005 2000 10 1990 15 1980 20 1985 25 1970 30 1975 35 1960 40 1970 40 1955 45 1955 45 1950 50 1960 60 1945 55 1940 60 1935 65 1955 55 1950 i60 z:, 1945 £; 1930 70 " 1925 75 ~65 1920 H in h " 'C s ( d p m ig ) 2011 0.05 T 85 1910 90 dong va tuJi tram 10 +' ++ ++ ~ + K ~80 1, 1915 0.1 +~ r-: ~ s: 15 ~ e lf) SQU tai c(Jt khoan HP08 2: Tu6i tr6m tich theo LKJIHGFEDCBA IL 2 v J kit qua tac tl9liing " 'P b ( d p m /g ) 0.10.01 tic h va HP 10 VCSBD V~ t6c dQ I~ng dong tram tich: nghien CUunay, nhom tac gia moi chi xac dinh duoc gia tri trung binh cua t6c dQ I~ng dong tram tich VCSBD D~ co diroc k~t qua chi ti~t v~ t6c dQ lang dong tram tich theo thai gian dn k~t hop su dung voi cac phirong phap khac nhir: Phuong phap ky thuat huynh quang tia X d~ quet cQt khoan (X-ray fluorescence -XRF core scaning), ky thuat nhi~u xa tia X (x-ray diffaction) d~ nghien ciru khoang v~t set va phan co h9C tram tich K~t qua tu6i tram tich co dQ chinh xac cao, voi chi~u dai cQt khoan xfrp xi 100 em da co th~ xac dinh duoc tu6i lap tram tich yang 100 nam cho cac vung cira song va cac thuy VI,fCyen bo la kha phu hop K~t qua kha tuong d6ng voi cac k~t qua nghien ciru khac cua cac tac giai tren Th~ gioi thuoc cac thuy VI,fCkhac nhau: H6 [34], vung cira song Amazon [31] So sanh t6c dQ I~ng dong tram tich VCSBD voi cac thuy vue khac: No cao hon h~ dfim pha Tam Giang - cfiu Hai (0,31-0,60 cm/nam theo [2]), thfrp hon cira Ba Lat (0,70-3,00 cm/nam theo [13], thfrp hon so v61 cac thuy VVCyen bo Malaysia (1,57-8,64 cm/nam theo [36]) Day la k~t qua nghien CUudang tin c~y diroc ki~m soat va lira chon tir ban dfiu: Cac cQt khoan duoc II,fUchon thu theo cac doi hinh thai - dQng lire theo quan di~m dia rnao bo bien cua cac tac gia n6i tieng tren Th~ gioi [5], [26] va cac nghien CUu co ban cua cac tac gia Tiiu ban Dia chat va Tai nguyen, Khodng san biin 311 H6i nghi Khoa h9C Dia cMt biin toan quoc I[m tM LKJIHGFE If mroc [12], [22) Cac mftu v~t diroc phan tich bang thi~t bi va phuong phap hi~n dai K~t qua diroc tinh toan theo co s6 Iy thuyet hien dai va cac phuong trinh toan da duoc ki~m nghiem va sir dung ph6 bien tren th~ gioi (nhir da d€ c~p cac muc d~t v~n d€ va phan phirong phap nghien ciru) KETLU~N Phuong phap nuclit phong xa 210Pbva 137Csda duoc ap dung danh gia t6c lang dong va tu6i tram tich tai cQt khoan VCSBD Trong vong vai chuc nam d~n 100 nam qua, t6c dQ lang dong tr§.m tich vung tang d§.n phia bien: tir 0,69-0,75 cm/nam va khoi lirong tich tu/I cm 21a 0,5198 g/cm 2/nam (tai cQt khoan HPIO) d~n 0,82-0,97 cm/nam va khoi luong tich tu/l cm la 0,8045 g/cm 2/nam T6c dQ I~ng dong tram tich VCSBD cao hon cac thuy V\ICyen tinh (h6, d§.m pha), thap hon vung cira song chau th6 (song H6ng) K~t qua lang dong tram tich phan anh duoc kha nang cung dp tram tich cho vung cira song hinh ph~u: Giau tr§.m tich hon mot s6 V\ICmroc W nhien yen tlnh va ngheo tram tich hon vung cira song chau th6 H o p tac nghien ciru giua Lai cam an: Nghien ciru duoc tai tro boi Ti~u Du an -ZYXWVUTSRQPONMLKJIHGFEDC Vien Tai nguyen va Moi tnrong bien (IMER), Vi~t Nam va Phong Thi nghiem Trong di~m Quoc gia Dia ch~t bien, Dai hoc Tongji, Thirong Hai, Trung Quoc Nhom tac gia xin bay to loi earn on chan d~n co so tren Nhom tac gia cling bay to loi earn an chan d~n Giao sir Chen-Feng You thuoc Phong thi nghiem Dia hoa d6ng vi, Trung tam nghien ciru h~ thong dQng hrc Trai D~t, Truong Dai h9C Cheng Kung, Dai Loan va TS Hoang Van Long, Truong dai hoc Mo - Dia chat, Vi~t Nam da cung thao luan v€ phirong phap tinh toan tu6i tram tich va d6ng vi phong xa TAl LI¥U THAM KHAo I Ali Arman Lubis, 2004 Constant rate of supply (CRS) model for determing the sediment accumulation rate in the coastal area using 210Pb.Coastal Development, pp 9-18 Albertazzi., Bellucci L.G et aI, 2007 210Pb and 137Csin sediment of Central Vietnam coastal lagoons: Tentitive assessment of acculation rate Marine Science and Technology Supplement 1, pp 73-81 B.S Shukla, 1989 An evaluation of the CIC Model of 210PbDating of Sediment Eviron Geol Water Sci, Vol 14, No.1, pp 73-76 Springer-Verlag New York Inc Bergan T.D., 2002 Radioactive fallout in Norway from atmoshperic nuclear weapons tests [J) Environment Radioactivity, 60, pp 189-208 Bird E., 2000 Coastal geomorphilogy An introduction John Wilet and sons LTD Chichester-New York, pp 1-322 Chih-An Huh et aI., 2011 Modern «100 years) sedimentation in the Taiwan Strait: Rates and soure-to-sink pathways elucidayed from radionuclides and particle size distribution Continental Shelf Research, 31 (2011), pp 47-63 312ponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Tiiu ban Dia chat va Tai nguyen, Khodng san biin H6i nghi Khoa h9C Dia chat bien toan qu6c tdn tM 11 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Crozaz,LKJIHGFEDCBA G , et aI., 1964 Antarctic snow chronology with ZYXWVUTSRQPONMLKJIHGFEDCBA o Pb Geophysical Research, VoI.69, p 2597-2604 Do Minh Due et aI., 2007 Sediment distribution and transport at the nearshore zone of the Red River delta, Northern Vietnam Asian Earth Sciences, 29 (2007), pp 558-565 Do Minh Due et aI., 2011 An analysis of coastal erosion in the tropical rapid accretion delta of the Red River, Vietnam Asian Earth Sciences, xxx (2011) x x x -x x x (in press) 10 Huh, C.A et aI., 2006 Sedimentation in the Southern Okinawa Trough-rates, turbidites and a sediment buget Mar GeoI., 231, pp 129-139 11 Huh, C.A et aI., 2009 Modern accumulation rates and a budget of sediment off the Gaoping (Kaoping) River, SW Taiwan: A tital and flood dominated depositional environment around a submarine canyon Mar Syst., 76, pp 405-416 12 Dinh Van Huy, 1996 f)~c di~m hinh thai - dQng lire khu bo hien dai Hai Phong Luan an PTS Dia Iy - Dia chat, Truong Dai h9C Khoa h9C T\I nhien - DHQG Ha NQi, 127 trang 13 G.D Van Den Bergh et ai, 2007 Recent sedimentation and sediment accumulation rates of the Ba Lat prodelta (Red River, Vietnam) Asian Earth Sciences, 29, pp 545-557 14 Goldber E.D., 1963 Geochronology with lead 210 In: Radioactive Dating [M], pp 12l131 IAEA, Vienna 15 He Q., Walling D.E., et ai, 1996 Interpeting the 137Cs profiles observed in several small lakes and reservoirs in southern England [1 ] Chemical Geology, 129, pp 115-131 16 Jay Stratton Noller et ai, 2000 Quanternary Geochronolgy methods and Applications Lead-21 geochronology, pp 115-120 17 Krishnaswamy S et ai, 1971 Science Geochronology of lake sediments [1 ] Earth and Planetary Letters, 11, pp 407-414 18 Koide M., Soutar A et ai, 1972 Marine geochronology with 210 Earth and Planetary Science Letters, 14, pp 442-446 19 Milliman, J D et ai, 1983 World-wide delivery of river sediment to the oceans GeoI., 91, pp 1-21 20 Milliman, J D., et ai, 1992 Geomorphic/tectonic control of sediment discharge to the ocean: The importance of small mountainous rivers GeoI., 100, pp 525-544 21 Lu X., 2004 Application of the Weibull extrapolation to 137Cs geochronology in Tokyo Bay and Ise Bay, Japan [1] Environmental Radioactivity, 73, pp 169-18 22 Nguyen Th~ Tiep, 1993 Hinh thai - dong lire ven Luan an PTS khoa h9C Dia Iy - Dia be Delta song Hong (Holocen hien dai) chat, 170 trang Truong Dai h9C T6ng hop Ha N9i 23 LJ Turner, L.D Delorme, 1995 Assesment of 210 Pb data from Canadian lakes using the CIC and CRS models Environmental Geology, 28 (2) September 1996 Springer-Verlag pp.78-87 Ti€u ban Dia chat va Tai nguyen, Khoang sdn bien 313 tdn tM 11 zyxw H9i nghi Khoa h9C Dia chdt bidn toan quoc 24 Dang Hoai Nhon va nnk., 20 11 Lang dong tram tich tren bai trieu Bang La va NgQCHili, Hai Phong Khoa hQCva C6ng nghe bien, T11 (2011), Nol, tr 1-13 ISSN LKJIHGFEDCBA S -3 2S Oldfield, F., Appleby P G et ai, 1978 AlternativeZYXWVUTSRQPONMLKJIHGFEDCBA Pb dating: results from the ew Guinea highlands and Lough Erne Nature (London), Vo1.271, pp 339-342 26 O.K Leontyev, L.G Nikiforov, G.A Xafijanov, 1962 Dja mao be bi~n Ban dich tieng Nga, 372 tr Khoa Dja Iy, Truong DH Khoa hoc TI! nhien, DHQG Ha N ti I~ Liru tnr Vien Tai nguyen va M6i tnrong bien, Hai Phong • 33 Vinh V.D, et ai, 2011 The impact ofHoa Binh dam on distribution of suspended sediment in coastal areas of red river delta Proceeding of and Technology, Vol 3, pp s" National conference of Marine Science S -4 34 XU Hai, AI Li, et ai, 2006 Geochrology of a surfacce core in the northern basin of Lake of Lake Qinghai: Evidence from 210 Pb and 137 Cs radi~nuclides Chinese journal of geochemistry, pp 301-307 3S Zbigniew Pruszak et ai, 200S Hydrology and morphology of two river mouth regions (temperate Vistula Delta and subtropical Red River Delta) Ocenologia, 47(3), pp S -3 S 36 Theng, L.T., Ahmad, Z., Mohamed, C.A.R., 2003 Estimation of sedimentation rate using 210 Pb and 21O pO at the coastal water of Sabah, Malaysia Radioanalytical Chemistry, Vo1.2S6, pp 314 and Nuclear l1 S - t u « ban Dia chat va Tai nguyen, Khoang san bidn H(Jinghi Khoa h9C £Jia chdt biin toan quoc ldn tM IIMLKJIHGFEDCBA SUM M ARY IN IT IA L RESULTS GEOCHRONOLOGY O F STUDY OF M ODERN BY M ETHODS IN S E D IM E N T A T IO N S E D IM E N T S RATE IN T H E B A C H AND DANG ESTUARY O F P b A N D zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 137CS R A D I O T R A C E R I B u i V a n V u o n g , L iu Z h i F e i, I T r a n D u e T h a n h , I T r a n D in h L a n , C h i-A n H u b , T u o S h o u tin g , I D a n g H o a i N h o n , I N g u y e n V a n Q u a n , I N g u y e n D a c V e , I D in h V a n H u y , I N g u y e n D in h K h a n g I-Institute of Marine Environment and Resources - VAST 2Tongji University, Shanghai, China E-mail: vuongbv@imer.ac.vn The Bach Dang estuary is very large (after the largest Dong Nai estuary) It is so important in Vietnam because where has Haiphong Seaport and in the future, this area will have also Lach Huyen deep-water port This estuary consists of high abundant in natural resources concerning of tidal channels and ecosystems such as mangroves and tidal flats etc In addition, the sediments and topography (sedimentary rates and channel siltation) in this area have been changed strongly and directly impacts on the resource values and economic activities, especially the seaport logistics The related issues have attracted alot of scientists in the fields of delta evolution, hydrodynamics, geomorphology, This paper presents initial results of the studies for the sedimentary transport, etc sedimentation geochronology of modern sediments in the Bach Dang estuary Sedimentation from 2IoPb and I37CS profiles accumulated/area rangedfrom has been varied from rates and rate derived 0.69 to 0.97 cm.yr' and mass 0.5198 to 0.8045 (g.cmi.yr '} The 210Pbwas used to calculate geochronology of modern sediment cores in the Bach Dang estuary within 100 years and 137 C ZYXWVUTSRQPONMLKJIHGFEDCBA s should be used as an independent tracer to verify the results obtained from 210 P b K EY W O RDS: Tiiu ban Dia cha: Sedimentary rate, geochronology, Bach Dang, va LKJIHGFEDCBA T a i nguyen, Khodng san biin 21O Pb, I37Cs 315 ... dinh hoacbien tich va 210Pb phan b6 d~n vi d6i qua thai gian Do vay, hrong 210Pbex bang hrong 210Pb t6ng tnr di luong 210Pb diroc san xuat tai ch6 Co me hinh tinh toan cho 210Pb d~ xac dinh tu6i... In210Pbxs(z)co d6 thi ngiroc voi kh6i luong tich tu tren mot don vi dien tich; w: k~t qua cua mat c~t 210Pb la tuyen tinh va goc d6c la: -"A21ofl 12.4 Mo hlnh tinh tugi tram tich SiI dung 210Pb. .. trinh phan cua 226Ra va excess quyen Y nghia d9 phong xa (activity) tich 210Pb" diroc 210PbelOPbex) nhan diroc tir cua 210Pb pharr b6 theo d9 sau nhan duoc rieng qua trinh phan theo lu~t ham s6