Tiến hóa địa chất vùng cửa sông bạch đằng trong holocen 1993

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G IA o-ovc vA D A o T~O
TRuO NG

D ~ I HQC

T O N G H < ;1 PHA N Q I

TRAN Due TH~NH

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TIEN HOA DlA CHAT
VUNG CUA SONG B~CH DANG
TRONG

HOLOXEN

(Tom tiit lu~n an phd tien si Dia

I

Iy - Dia

Chuye n nga nh :

Dja chat

Ma s6

1.06.01

Hit NQi 1993

c h a t)


LU~N AN NAY utror:
KIIOA D!A

N g lJ a i h u 6 n g

IIOAN TIIA'-IH T~J

LY - f)!A CIIAT. TRU(Y~(; D.~l HOC

aZYXWVUTSRQPONMLKJIHGFEDCBA
d im :

2. DANG DUC NGA, Pho Giao sir - Ph6 Tien SI Khoa hoc dia chat _
Khoang vat.

nh?n

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xet

...................

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T in h c a p th ie t cua lu ~ n a n .
Vung cira song (yCS) Bach Dhng co mot vi tri d~c biet quan trong trong
M thong kinh te' xli hQi mien Duyen hai phia b~c Vi~t Nam va la m(>t vung
hoat d(>ngkinh te'soi dong tren nhieu linh Vl!-Ckhai thac bi~n. Day cung la
noi c6 nhieu van de cap bach d~t ra ve khai thac hop 19 tai nguyen va bao v$
moi truong. Nhirng ysu cau nay doi hOiphai co hi~u bie't ro ban chat tl1 nhisn
vung cira song Bach Dang, trong do co van de tie'n hoa dia chat Holoxen.
N ghien cuu tie'n hoa dia chat Holoxen vung cia song Bach Dang, noi co sir
tirong tac manh me gnra luc dia va bi~n la huong nghien ciiu mdi d nude ta,
co kha nang to Ion gop phan dap iiug nhung doi hoi cua thuc ti~n kh~ thac
quan 19 doi bo.

· ~O~(; 1I<'y1'IIA ~()1 ZYXWVUTSRQPONMLKJIHGFEDCBA

1. NGUY~N CAN, Giao sir - Tien sf Khoa hoc dia chat - Khoa ng vat

N g lJ a i

G I6 1 T H I$ U C H U N G L U ~ N A N

"0 "tO~ f)!A CII'\T.

.

Ml;IC d ic h cua lu ~ n a n .
N ghien cuu qua trinh tie'n hoa dia chat Holoxen VCS Bach Dang lam
co sd cho viec du bao nhung bien d(>ng ciia moi trirong dia chat trong
tuong lai va d'e xuat cac 9 kie'n SI1 dung hop 19 Uti nguyen, bao v~ moi
truong vung cira song.
vl;I eua lu ~ n a n .
- Phan chia va lam ro ban chat ciia M thong moi trucng tram tfch
Holoxen VCS Bach Dh g.
- Xac dinh cac qua trinh dia dong 111cHoloxen VCS Bach Dang anh
hudng den tien hoa dia chat.
- Xac dinh ban chat cau true ciia VCS Bach Dang.
N h i~ m

N g lJ a i n h ? n

xet

2 :

va d i~ m m a l cua lu ~ n a n .
1- Mci truong tram tich (MTTT) Holoxen vung cira song Bach Dang
dia ven bi~n, dai ven bo),
duoc phan chia thanh 2 phirc M (dong bang 11,J.c
6 ki~u (ho-dllm Illy, aluvi, chau th6, estuary, V1,J.ng
bi~n va vjnh ven bo), 3
phu ki~u (ddi trieu, ddi dudi trfeu, ddi ran san ho) va 9 dang (bai b'6i chau
th6 ngap tri'eu, bai tri'eu Illy, bai tri'eu thap, de cat bi~n, bai cat bi~n, delta
trfa u xuong, chau th6 ngam, lach tri'eu song va day vinh nho ven bo).
2- Tie'n hoa dia chat vung cia song Bach Dhng trong Holoxen duoc chia thanh

ba thai kY:M5i thai kYMt daU bang qua trinh bi~n tie'n (hoac bi~n ! t in ) , Mt thuc
bang' qua trinh biE!nlui. Thai ky thu nhat, Holoxen sdm giua (11-3 nghin nam
truce). Thai kY thu hai, Holoxen muon (3 de'n 0,5-0,7 nghin nam truce). Thai
ky thir ba b~t dau tit cu6i Holoxen muon (0,5-0,7 nghin nam qua). M6i thai kY
gom mot sO"giai doan ung vdi cac kiE!umoi truong tram tich nhat dinh,
N h lin g lu ~ n d i~ m b a o v ~

Co quan

nh?n

xet :

Luan an nay se dU<;1C
bao v~ ta i HQi dong cham lua n an Nha nude
hQP ta i 'I'ruo ng Dai hoc T6ng H<;1pHa Noi.
Vao h'6i .....

gio .....

ngay .....

tha ng .....

narn 1993.

Co tM tlm hi6u luau an ta i thu vien Qu6c gia va thir vie n 'I'rucng
D!;lihoc Tong H<;1pHa NQi.

1

3- Vung cira song BI;l.ChDa.ng co ban chat cau true la mot estuary (cira
song hinh pheu) ducc hinh thanh tren co sd tuong tac gnta qua trinh phat
tri~n mot graben dang sut chim vdi sir dang cao muc mrdc bi~n chan tinh,
sir thieu hut b'oi tich va thuy trieu bien d9 ldn.

YgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
n g h ia kh o a h Q C va th u c ti~ n .
Luan an gap p h a n lam r6 qua trinh tien hoa dia chat Holoxen ven bo
phia bac Vi~t Nam trsn co sd quan M tirong tac gnta cac qua trinh kisn
tao, chan tinh va tr~m tich. Ket qua luan an la dang gap ban d~u cho
nghien cuu dia chat Holoxen a mot estuary cua Viet Nam vdi tu each la
mot th~ dia chat d9C lap,
Ket qua luan an gap phan tao dung co sd khoa hoc d~ giai quytit cac
nhiern vu quan tro ng cila thuc ti~n. Viec khang dinh ban chat cau true
estuary la co sa tham khao d~ lira chon djnh hirdng phat tri~n kinh te, S11
dung hop Iy tai nguye n, bao v~ moi trucng VCS Bach Dang, gap p h a n xac
dinh kha nang phat tri~n cum cling Hai Phong.
Nhung ket qua ciia luan an da diroc s11 dung trong cac de tai cap nha
nude 48.06.14 "Di'eu kienZYXWVUTSRQPONMLKJIHGFEDCBA
tt:f nhien
va kha nang nguon lqi dai ven bi~n
Vi$t Nam" do GS. TS Dang Ngoc Thanh chu tri; 48B.05.02 "Nghien cuu
S11dung hop Iy cac bai trfeu Ia y ven bi~n phia bac Vi$t Nam" do PTS
Nguyen Chu Hoi chu trt. dir an VIE 88/014 cua UNDP "Khao sat sa boi
cang Hai Phong", cac du an cua thanh phd Hai pho ng "Xac dinh nguyan
nhan va I~p giai phap pho ng cho'ng xci la dao Cat Hai trsu quan di~m dia
chat dQng luc"; "N ghien ciru sa b6i M xac dinh tfnh kha thi ciia viec xay
dung ben ca Ngoc Hai" do tac gia chu tri.

te.

Tal Ii~ u thirc
Luan an duqc xay dung chti yeu tu till lieu thuc te cua tac gia khi tham gia
cac de tai 48.06.14; 48B.05.02, du an VIE/88/014 va de till cap thanh phO "Moi
truong dja chat ven bO Hai Phong" ma tIlc gia la chii nhi~m. L~n an cOn s11
d\lng ke' thua tai li~u cong trinh ban do dja chat Hai Phong 1/200.000 (1978);
1/50.000 (1992) cua C\,lCDja chat Vi~t Nam, cac till li~u khoan cUa Doan dja
chat thuy van 37, sa X3.y dt:fng, sa Giao thOng Hiii Phbng, Vi~n Thiet ke' giao
thOng (BQ Giao thOng va Bttu di~n), Vi~n DjaaZYXWVUTSRQPONMLKJIHGFEDCBA
c M i t (Vi~n khoa hQc Vi~t'Nam)
cac till li~u moi truong tt:f nhien va sinh thai luu tr11 t~i Phan vi~n Hai duong
hQc Hai PhOng (P.V.HDH).
L~n an stt d\lng ke't qua phan tich 200 mciu eel sinh va vi eel sinh (tao silic

mem do Lang van Ken va san ho do N guyen Huy Yet xac dinh), 500 mftu

co hoc tram tich (NguyenChu Hoi, Tran Dinh Lan va Vii Dinh Tien phan
tich), 200 mciu khoang vat nang va nhe (Nguyen Quang Tuan phan tfch),
1000 mau tram tich lo hrng va 2000 chi tieu dia hoa (Nguyen Dire CI! va
N guyen Phuong Hoa phan tich), 20 mau ron ghen dinh luong (Pham Van
An phan tfch). Hau het cac mau diroc phan tich tai PY.HDH Hai Phong,
Luan an con s11 dung cac till lieu cong b6 co lien quan cua nhieu tac gia.
G i6 i th i~ u k e t q u a n g h ifm ciru.
Luan an gom 121 trang danh may, trong d6 c6 20 bi~u bang, 53 ban do, so
do, hinh ve minh hoa, 8 anh tir lieu va 149 till lieu tham khao, M9t sO ke't qua
nghien ciru cua 1$ an dfl duoc trinh bay trong cac 000 cao de till ma tac gia
tham gia, trong cac bill bao, thong bao khoa hoc da cong bO'cua tac gia.
Luan an diroc hoan thanh tai B¢ mo n Dia chat, Khoa Dja ly-Dja chat,

Truong D~i HQc T6ng Hop Ha NQi duci str hucng d§.n true tiep ctia GS.TS
N guyen C§:n v a PGS.PTS D?ng Duc N ga.
Trong qua trinh hoan thanh luan an, tac gia luo n nhan diroc su quan
tam giup do cua BQ men Dta chat, Khoa Dja li-Dia chat, Truong D~i HQc
Wing Hqp Ha NQi, PV.HDH Hai Phong.
Tac gia cung luo n nhan dU<;1C
nhung g a p y quy bau cho luan an cua
PTS. Nguyen Chu Hoi, PTS. Nguyen Dinh Hoe, GS.TS T6ng Duy Thanh,
PGS.PTS Nguyen Vi Dan, PTS vo Xuan DQ, GS.TS Le Duc An, PGS.TS.
Pham Van An, GSTS Nguyen Dich Dy, PGS.TS. Dang Van Bat, PTS. D6
Tuye't, PGS.PTS. Nguyen Van Phuc, PTS. Le Van Manh, PTS Lai Huy
Anh ... 'I'ac gia luo n nhan ducc sir giup d B tan tinh v'e mo i mat cua cac
d'ong nghiep d pho ng Dja chat-Dja Ii bi~n, PV.HDH Hai Pho ng va sir dQng
vie n khich I~ cua d'ong nghiep, be ban xa g a n .
Nhan dip nay tac gia xin dU<;1C
bay to long biet on sau sdc v a chan thanh
dO'i vdi cac co quan va cac nha khoa hoc noi tre n.

do Tran Duc Th~nh va Dao Thj MiEm xac djnh, trung 15 do N guy~n N gQc va
Nguy~n Hl1u Ctt, bao ttt phan do Dinh Van Thu?n va Nguy~n Bao Khanh, than
2

3


N O I D U N G gfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
LU~N A N
CHUONG

I zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

KHAI QuAT TINH HlNH NGHIEN COO DIA CHAT
HOLOXEN vUNG CUA SONG. PHU'dNG PHAP :t.WHIEN COO
I- KHAI QuAT TINH HINH
vUNG CUA SONG.
Tre n the' gidi, da c6 nhieu

NGHrEN

cong trinh

den tac dong cua con ngiroi. Voi nhung quan diem nhu vay, M phucng
phap diroc lira chon nhu sau :

ctrtr

DIA CHAT HOLOXEN
.

nghie n cuu ve d~c diem phat

trien va cau true cac vung cira song n6i chung (Klenova, 1948, Xamoilov
1952, Shepard 1963 ... ), estuary n6i rieng (Lauff 1967, Lafond 1967 ...).
Nhung tien hoa dja chat Holoxen cac vung cira song mdi diroc quan tam
g a n day (Roy 1979, 1984).
.

1- Cac phucrig phap nghie n cuu c6 sinh dja tang (phan tich tao silie,
trung 16, bao ttt phan, than me m ... nghien cuu phuc M sinh thai).
2- Cac phuong phap nghie n ciiu tram tich bien hie n dai. Phuong phap

g6p p h a n x a c d j nh kieu tu d n g tra m tich v a d o ng 11,l'C
tich tu .
3- Pha n tich tu lieu lich sii, khao cel va tueli tuye t dO'i.
4- Cac phirong phap nghien ciiu dia mao (phan tich cac kieu dia hinh cung
nguon gee, M thong dirong bC1cel, them bien, ngan bien; phan tich dong lire
hinh thai; phan tich trac hrong lap lai ...v.v.).
5 - Phuong phap phan tich tan kien tao va kien tao hie n dai.
6 - Phucn g pha p pha n tich tudn g - c6 d ia ly .
7 - Phuong phap phan tich tai lieu vien tham va ban do.
8 - Phuong phap danh gia anh huang nhan tac nham xem xet tac de)ng
cua con ngiroi nhu la mot nhan to' d¢ng lire a VCS.

Hlnh the vung cira song Bach Dllng da duoc mo ta tU nhieu the' ky triroc.
Cuol the' kY XIX, ngiroi Phap (Caxtex, Renaux ...) da tien hanh khao sat thuy
van va dia hinh d day. Cong viec nay diroc d(Lapique 1932, Gauthier, 1938 ...), vao nhung nam 60 (cac chuyen gia Lien
C H U O N G II
xo) nham .cai tao, phat tri~n cum cang Hai Phorig.
NHUNG
DAC
TRVNG
Cd BAN vE DIEU KI$N
Ljch stt dia chat Holoxen VCS Bach Dang diroc de cap den trong cac
TV NHIEN vUNG CUA SONG BACH DANG.
cong trinh banZYXWVUTSRQPONMLKJIHGFEDCBA
d b dia chat 1/200.000
(1978) cua Doan dia chat 204,
I- V1 TRI vA DlA HINH.
1/50.000 (1992) cii a Doa n dja chat Ha no i va trong cac co ng bo' ciia
VCS Bach Dang nam a ven bien dong F A C dong bang Bac B¢, tren khong

n hie u tac gia (Nguye n Dif c Tam 1969, 1982 ... , Hoang Ngoc Ky 1976,aZYXWVUTSRQPONMLKJIHGFEDCBA
co dinh g'an Ben Trieu, day gan
gian phan nhanh cua song Kinh Th'a00
1 9 8 9 . . . D b Van Tq, 1988, Luu Ty 1980 ... ).
trung duong diing sa u 6m chay ttt-f1o Son sang tay nam Cat Ba. Vung cira
G'an day, trong cac de Uti cap nha nude 48.06.14 (1985) ; 48B.05.02 (1990)
song
diroc phan dinh tuong dO'ir6 va nam giira cac dill mii Kien An-no Son
do PV.HDH Hai Phong chu tri, van de tien hoa dia chat Holoxen va cau true
(tay
nam)
; Mac Khe-Yen Lap (phia bac) va q u a n dao Cat Ba (phia dong). Bill
VCS Bach Dang cling diroc de cap so b9. a nhirng cong trinh neu tren n¢i
trieu fay, bill trieu thap, Iuong lach va ddi bC1ngam la nhung don vi dia hinh co
dung dia chat Holoxen chira diroc nghisn cuu sau. Tien hoa dia chat Holoxen
ban
va d a c trung cho vung cira song.
mdi dung a mire bien d6i mire nude, dirong bC1,chua di sau vao nhirng bien
d6i ban chat HEm quan den tirong tac n¢i, ngoai sinh. Chua co cong trinh nao
di sau nghisn ciru de khang dinh ban chat cau true VCS Bach Dang. Cung
chira c6 c6ng trinh nao nghien ciru ve dac trung va phan chia moi trtrcng
tram tich Holoxen VCS. Day chinh Ia nhung van de co ban duoc dat ra va
giiii quyet trong luan an nay.
II- PHUONG PHAp NGHIEN CUu.
N ghien CUlltien hoa dia chat Holoxen VCS Bach Dllng duoc dua tren quan
diem M thong va t6ng hop, bao ham n¢i dung cac phuong phap nghien ciiu lich
sU:dia chat, dia chat D~ tu va dia chat hi~n d:;tiddi bC1.N gom lam sang to tien
hoa trong qua khu, hi~n u p , can pMi cO nhllng dl,l'bao bien d6i trong tUdng lai.
Day la hudng nghien CUlltiep ~n vdi dia chat moitruC1ng, trong d6 c6 xem xet
4

II- KHI HAu vA THuY VAN.
khu vue nhiet ddi gi6 mua, mua gi6 dong nam
Vu ng cira song nam
vao thang 5-9 ; mua gi6 dong bac thang 11-3. Nhiet d¢ trung binh nam
23,5°C, hrong mua 1500 - 2000mm/n~m. TO'c d¢ gi6 trung binh 3-4m/s,
cue dai 45m/s trong bao. Hang nam chiu anh huang cua 2-5 con bao.
Thuy trfeu kieu nhat trieu d'eu dien hinh, bien dC)CI,l'C
d:;ti 4-4,5m. Dong
chay trieu c6 vai tro uu the, to'c de) trung binh 20-50cm/s, cue dai
150-180cm/s. Song bien ngoai cira cao trung binh O,5-1,Om, thjrih hanh
3
cac hudng D, DN va N. DC)man nude 0 ,5 - 3 2 % 0 , dC)due 10-1000g/m . pH
= 7,2-8,3. Hang nam song tai ra khoang 11-14km 3 nude va 4 tri$u tan
phu sa.

a

5


III- DAc DIEM DlA CHAT KHU ZYXWVUTSRQPONMLKJIHGFEDCBA
V lJ C .
bill bi~n) gom cat hat nho, trung, mau xam, nau do, yang, 19 tren mat.
Trim binh do kien true khu V1!c,V CS Bach Dang nam gnra vung mii uon
1.3 Phan tren : tu6i cuo'i Holoxen giita (lb, am QIV l-2hh_c) day 1-6,5m,
nep khoi tang Quang Ninh va trung Kainozoi Ha Noi. 'I'ai day co mat cac da
trung binh 4m. Tram tich ho d'am yen bi~n gem cat bun, bun bot long
19 aZYXWVUTSRQPONMLKJIHGFEDCBA
d cac doi, mii thap ven ria.

luc nguyen va cacbonat tu6i Mezozoi va PaleozoigfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
nhao mau xam, xarn den, ngheo bao t11phan, chii yeu gap tao silic luc dja,
Trong pham vi VCS, mong da gOcchim sau den 50-70m doc true song Cam.
kho ng 10 tre n mat, phan bO'd trung tam vung cira song. Tram tich song
ThO'ng Pleixtoxen gom hai M fang. R~ fang Ha Noi (QII-IIlhn) day
bi~n gcrn bot, bot set xam nau 40 ne n b'e mat dong bang cao 2-4m.
2-30m g o m cuo i, sa n cat nguo n goc aluvi. H~ fang Vinh Phuc (QIII2 yp)
2 . T h o n g H o l o x e n t re n, H~ t a n g T h a i b i n h (QIy3tb).
nguo n goc bi~n, darn Illy bi~n, song bi~n va aluvi, ki~u chau th6, day
Day I-10m, trung binh 3m, gom 3 phan :
10-50m. Tram tich Holoxen day I-15m.
3
2.1 Ph'an dudi : tu6i dau Holoxen muo n (mQIV tb-a), tram tich bien
IV- SINH VAT vUNG CUA SONG.
thuoc hai ki~u nguo n gee. 'I'rarn tich trieu thap va dudi trieu, gem cat bet,
Sinh vat VCS rat da dang, phong phti va gom nhieu nhorn khac nhau. Co
bo
t mau xarn nau phong phii tao silic bi~n, than me m bi~n, trung 16,ngheo
hai nhorn quan tro ng tham gia vao cac qua trinh tram tieh. Do la nh6m sinh
bao
tti phan. Day 0,5-1,2m, kh6ng 1(>tre n mat va phan bO'a trung tam
vat day (260 loai) dao hang hoc va cung cap va voi cho tram tlch. Nhorn thuc
VCS. Tram tich bai bien, de cat bi~n gom cat nho, xam, xamvang day
v~t ngap man (23 loai) phan bO'tU mire bi~n trung binh (MBTB) tro len,
I-3m, I¢ tren mat.
tham gia tich cue VaGqua trinh d'am Iay hoa, Nhieu sinh vat quy hiern, co
3
2.2 Phan giua : tu5i d'au va gitra Holoxen muon (brn, am, mQIV tb-b).
gia tri kinh te cao va la dO'ituong nuoi trong-danh bat quan trong.FEDCBA
Tram tich dllm Iay bi~n ph6 bien, gom bot, bo t set deo quanh xam xanh

C H U O N G III
chiia nhieu manh than r~ va phan hoa TVNM, ngheo trung 16 va than
DlA TANG vA MOl TRliONG TRAM TICR ROLOXEN.
rnern, uu the tao silic luc dia, day 0,3-1m, it 1(>tre n mat. 'I'ram tich song
I- DlA TANG TRAM TICR HOLOXEN.
bien day 0,5 - 1,5m gorn bot, bo t set xam nau phan bO'a ria tay nam vung
cira song ..Tram tich bien (tudng de cat bi~n) gom cat nho xam vang.
Trong luan an, thoi gian Holoxen sdm khoang 11-7,5 nghin nam trirdc ;
3
2.3 Phan tren, tu5i cu6i Holoxen muon (m, ma, am, bm, IbQlV tb-c), gom
Holoxen giua 7,5-3 nghin nam truoc va Holoxen muon 3 nghin nam lai day.
Nho tai lieu phong phii vdi nhieu ket qua phan tich eelsinh, dac di~m tram
nhieu nguo n g6c : bi~n, bi~n song, song bi~n, dam fay bi~n, ho dam, day
thuong 0,1-1,5m. Thanh phan tu set den cat nho mau xam, xam nau, nau.
tich dil cho phepphan chia chi tiet dia tang, xac dinh cu th~ nguon goc va
phan bO'tram tich Holoxen VCS. Tu5i tram tich diroc xac dinh nho lien ket,
II- MOl TRliONG TRAM TICR HOLOXEN.
so sanh co h~ thong cac tu lieu ve c6 sinh-dia tang, dia mao, khao cel,lich S11,
1. Pha n loai mo i t r U f 1 n g t r a m t i c h H o l o x e n .
cac gia tri tu6i tuyet doi hien co d vung nghisn ciru va Ian can,
Dua VaGd~c trung tudng trarn tich, hinh thai bon va dong lire cua qua
L'I'hong'NMLKJIHGFEDCBA
H o l o x e n d u o i - g i u a , he t A n g Hai H u n g (QIyl-2hh).
trinh tich tu ket hop xem xet cau true tq nhie n M yen b d , moi trirong
Day I-11m, trung binh 9m, gom ba phan.
tram tich Holoxen VCS Bach Dang duoc phan chia thanh 2 phirc M (dong
1.1 Phil n dud i : t u d i cuc'i Ho l oxe n sd m-dil u Ho lo xe n gill a
bang luc dia va dai ven bo), 6 kieu (ho d'am Illy, aluvi, chau th5, estuary,
(a,IQIV l - 2hh-a). Tram tich aluvi go m cat nho xam vang, ngheo di tich sinh
vung bi~n va vinh ven bo), 3 phu ki~u (ddi trfeu, ddi dudi trieu va ddi ran

vat va tram tich ho dam luc dja, gorn set bot xam phdt vang luc chira tao
san he), 9 dq.ng (bai boi eMu th6 ng~p trfeu, bili tri'eu Illy, bai tri'eu thap,
silic I1,lC dta. Day 1,5-3m, kh6ng 1(>tr€m m~t va phan b6 hq.n che.
de cat bi~n, bai cat bi~n, delta tri'eu xu6ng, Iq.chtri'eu song, chau th5 ng'am
1.2 Ph'an gill a : tu5i Roloxen giua (mb, mQIV l - 2hh-b) day 0,5 - 6ni..
va day vinh nho ven b d .
Tram tich dam fay biE!n-bi~n,gom set, set b¢t, cat b¢t xam, xam den, xam xanh,
1.1 Moi truong tr'am tich Roloxen sam - giua.
.
chua phong pM ta~ silic bi~n, phan hoa thqc v~t n@.p m(m (TVNM), di tich
. _ Cac ki~u moi trudng tr'am tich ho dllm Illy va aluvi (cuO'iQlVl dllu
than ~ TVNM, ngheo trung 16,phong pM than nlem bi~n trong cae tha'u kinh
QlV2) thu¢c phuc M dong bling llJ,cdia ven bi~n.
2
cat b¢t. Phan b6 r¢ng, khong 19 trim m~t. Tram tich bi~n (tuong de cat bi~n,
_ Cac ki~u moi trUdng trllm tich vinh, vl.;lngbi~n (QlV ) thu¢c phuc h~
6
7


dai yen bo. Gom cac phu

ki~u ddi trfeu,

ddi dudi trfeu,

ddi ran san ho .

i truorig tram tich bai trieu Iay, bai trieu thap,
Phan biet' diroc ~ac dang mogfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

bai bi~n, de cat bi~n.
_ Ki~u moi t ruo ng tram
phuc

"
.'
._.
2
•
tich dam lay ria chau tho (CUOlQIV ) thucc

M dong bang luc dia yen bi~n va dang bai boi chau th6.

1.2 Mo i truo ng tram
_ K i~ u

ddi trieu,

mci tr~dng

hmh nguon

goc luc dia, nguon

gec bien va nguon

fay bi~n, nguon
thanh

gec sang bi~n (bien song), nguon gec dam

goc nhan sinh. M6i nh6m lai duoc chia

cac ki~u dia hinh tich tu va ki~u xam thuc, bao man. Kieu dia hmh

diroc chia thanh

cac dang dia hinh voi nhung

dac trirng ve hinh thai, tubi

dia hmh, thanh phan tra m tich va d o n g luc thanh tao.
phuc h~ dai yen be)aZYXWVUTSRQPONMLKJIHGFEDCBA
3
tich vinh bi~n (dau QIV ) gom cac phu ki~u
Trong nho m di a hinh ngue n goc bi~n, cac kieu, dang d ia hinh nguo n

tich Holoxen

tram

muon (thuoc

ddi dudi trieu vdi cac dang duoc phan djnh la bai trieu thap, bai

cat bi~n, de cat bi~n.
_ K.i~u mo i trucrig tr'am tich vun g bi~n (d'au va

g n fa

3

QIV ) vdi cac dang

diroc phan dinh la bai

trfe u

lay, de cat bi~n, bai cat bi~n, bai boi chau th6

ngap trieu cao.
_ Ki~u moi truong

tram

tich chau

3

th6 (cu6i QIV ) vdi ph6 bien dang

bai boi chau th6 ngap trieu.
_ Ki~u moi trircng tram tich estuary

g6c s6ng c6
bac

III

y

nghia

(l0-15m,

Ion. Da xac di nh dUQc ba them
QIII2),

d'au QlV 3).

(3-3,5m,

them

bac

II (4-6m,

C6 5 M de cat bi~n, thu

tich tu bien la them

QIV2)

va them

bac

I

tv tre da n ra phia bi~n :

H~ 1 (4,5-6m, QIV2); M 2 (3-3,5m, d'au Q1V3); M 3 thap nhat (2-2,5m,
giua QIV 3), M 4 (2,5-3m,
cuo'i QIV 3) va M 5 dang duo c tha nh tao
(3-3,5m).

Da xa c di nh duo c cac them
(giua QIV 3).

mai mo n do s6ng cao 2-2,5m

(d'au

QlV 3) va -0,5-1m
3
(cu6i QIV , khoang

nam qua). Gam cac phu ki~u doi trieu va doi trieu thap vdi 8 dang diroc phan

Cung da xac dinh duoc cac ngan an mo n bien tren vach bo da voi cao
5-6m (giua QIV 2) ; 3-3,5m (d'au QlV 3). Ngan 2-2,5m (QlV 3) the hien

dinh la bill tneu fay, bill trieu thap, delta trieu xu6ng, de cat bi~n, bill cat bi~n,

kh6ng r6. Tuong ung cac ngan an mo n d e u Urn thay cac b~ hau ha (Ostrea)

lach trieu song, chau th6 ngam va day vinh nho ven bo.

barn co d¢ cao tuong

2. Tinh pha, nhjp tram

tieh.

Tram

cira song Bach Dang

tich Holoxen

chua ket thuc,
hat tram

vung

co xu huang

tich phu thuoc

0,5-0,7

nghin

II- TAN KlEN

min dan nhung

thuoc

ve mot chu ky

khong r6 ret. S,-! bien d6i dQ

VaG do ng luc tich tu hen la sir thay d6i mire xarn

thV C co sa. Tinh pha, nhip th~ hien a su l~p lai cac ki~u moi truong
tich (hay ki~u tudng),

chu ky tram

nhip tre dan nhu sau :
Pha 1 : Holoxen sdm-giua,
dia, MT vinh-vung
Pha 2 : Holoxen

tich Holoxen

~rE ~

,
MT vu ng bien va

IV

RIEH TA.0 vA KIEN TAO HIltN DAr.

DlA MAO vUNG

ClrA SONG BACH DANG.

Dia hinh VCS B~ch DAng rat da d:;mg, phti'c t~p, voi ml,lc tieu nghien cuu
tien hoa doi bd, Iu~n an da philn chia dja hinh VCS B~ch Dhng thee nguyen
tAc cac ki~u dia hinh cling nguon gOc (Lukianova 1975).
d vting ctra song va Ian ~n co 5 nh6m dja hinh cling nguon gec la : Dia

TAO

vA

KlEN

TAO Hr:~N DAI.

1. D~e dir;m kien true tan kien tao (TKT) va kien tao hi~n da i
(KTHD).

d

vung cira sang Bach Dang va Ian can ton tai chu yeu 3 h~ dut gay hoat

dong trong TKT va KTHD c6 phuong
gay chu dao phuong TB-DN truct

TB-DN, DB-TN

va

a

vi tuyen, H~ dti't

bang trai trong pha Oligoxen-Mioxen muon

vdi tnrong ung xuat kien tao (UXKT) c6 true nen ep cue daiZYXWVUTSRQPON
0 1 phuong a vi
tuyen va truot bang phai trong pha Plioxen muon- D~

tU

voi truong UXKT c6

true nen ep cue dai phuong a kinh tuyen.
Trong pha Plioxen
Son, truong

muo n, gorn mot nhjp MT estuary.
CHUONG

DIA MAO, TAN

cac pha

,
,
gom ba nhip : Moi t ruo ng (MT) dam lay luc

va MT dam l'ay ria chau th6.
muo n, go m ba nhjp : MT vinh-vung,

MT chau th6.
Pha 3 : Cudi Holoxen

I- DAc

duoc chia thanh

tram

duong.

01

a vi tuyen

(j

phan my nam dirt gay Nui Deo - Do

U'XKT c6 true 'nen ep cue dai

DB-TN truot
c6 true

muon - D~ tu,

trai.

a phan

a kinh

tuyen va M diit gay phuong

dong bac dut gay Niii Deo - Do Son, truong UXKT

d6i hucng 90 d¢ thanh phuong a vi tuyen.

d day,

cac dut gay thu~n

lien ket voi cac dut gay DB-TN truc;1t phiii. Co che djch chuyen

nguc;1c chfeu tron cling trt,tc dut gay DB-TN da gay tach gian tl;lo nEm m¢t
graben

(j

trung

tam vting ctta sang Bl;l.chDa.ng (N guy~n Cfin, N guy~n Dinh

Hoe, Tran Duc Thl;l.nh va nnk 1993).
Tren binh do kien truc TKT va KTHD ph8.n bi~t duc;1c4 ddi : Doi nang
tuong doi m~nh trong

TKT va KTHD

(2); Ddi vang h~ tuong dei trong

(1); Ddi nang dieu hoa trong KTHD

KTHD (3) va ddi vang hl;l.tuong doi nwnh

8
9


(graben)

trong

Holoxen

(4) (hinh

1).

2. Bi~u hie n chuyen d()ng kie n tao hien dagfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
i va quan h~ vdi rmrc
nude chan tinh.
Till lieu phan

tich, dia mao va kien tao cho th a y aZYXWVUTSRQPONMLKJIHGFEDCBA
d vung

tich tirdng tram

nghien ciru bien d6i nnrc nude Holoxen
(1963).

Thea do, nnrc bi~n thuc

nay. Nhirng

phu hop voi quan di~m cua Shepard

te dang

lien t\IC trong

Holoxen

phan di cua d9 cao mire bi~n . duong bola
the ky qua, mire bien tM gidi nang chan tinh

tao. Trong

cho den hien

do nguyen

bi~n a tram H o n D su (sat ria tay nam VCS) nang cao 2,24 mm/narn
gian 1957·
Tucng

kien

kien

Mire

trong thai

Ngoc Th\IY, 1992).

1990 (Nguyen
quan

nhan

1.1,5mm/nam.

tao, chan

tri tuong d6i cua mire bi~n·

tinh

va tram

tich da tao nen su thay d6i vi

ducng be Holoxen

Ian sau VaG luc dia 5600 nam

truck

(ung vdi

vu ng cda song. Duong

vi

tri 5· 6m do nang
nam

truce

(ung

bo

kien tao);

lui ra phia biE£n VaG cu6i Q1V2, khoang

3500

2,5m do ha kie n tao va nang chan tinh);

Ian VaG phia luc dia VaG dau Q1V 3

vdi vi tri .

(itng

vdi vi tri cao 3 . 3,5 m do nang kien tao), lui ra phia biE£n VaG giira
3
Q1V (ung vdi vi tri · 1,4m do ha kien tao va nang chan tinh) va sau do
Ian v'e phia luc dia khoang
hop nang

chan

Chuyen

tinh)

0,5 . 0,7 nghin

den muc

d9ng KTHD

kha manh

Richter

khu

va

d9 Richter

bac dirt gay Kinh

dong

qua (do ha kieri tao ket

bi~u hien qua hoat dong dia chan

cira song va Ian can, dat tdi 5,1· 5,5
MSK· 64).a

nam

Om hie n nay.

6 s 10 s 7 a T a y nam

va chan d o ng 10

Mo n

>

vung

7(thang

Hai Pho ng, 4,6 . 5,0 d9

dut gay nay.

Chuyen dong KTHD bi~u hien a d?c di~m bien d6i

tram

=

tich tren cac doi kien true, B'e day Holoxen

0,7· 2,8 m; 2· 4m ; 4· 9m va tang manh

11· 14,8m

oe day

va phan b6 tudng

ttr doi (1) den (3) tang dan :
d

doi (4). Cac tram tich tirdng

bi~n trieu thap va duoi trieu hau nhu chi phan b6 d cac ddi ha hin.
T6c d9 nang
sau

kien

tao a ria nui,

Q1V2; 1,2 mrn/nam

mm/narn

VaG cu6i

Q1V:3. T6c

dao (doi 1) la 2,2· 2,4mm/nam

vao mra

gill a Q1V 3 v a 0· 0,5
d9 ha hin a ddi (4) trong Q1V 2-3 khoang

dau

vao

Q1V 3; 3,lmm/nam

O,17· 0,20mm/nam.
Bang

phuong

phap

lap mire danh

dau theo day ldp dam bi~n xam xanh

Q1V 3, da xac dinh

phan

b6 tudng

diroc t6c d9 va huang van do ng' kien tao tre n pharn vi
bai trieu lay (dam lay bi~n) nhir sau :

Ddi (1) nang 0,6 . 0,8 mm/narn
Doi (2) nang 0· 0,6mm/nam
Ddi (3) ha 0· 0,2mm/nam
Ddi (4) ha 0,2· 0,8

mm/narn

trong

trong

Q1V:3;

Q1V:3;

vao gil1a va cu6i Q1V 3;
VaG cu6i Q1v3;
10


sn FEDCBA
DO KitH

TR U C TAN NMLKJIHGFEDCBA
K IE H Tno. KlfH T A O H IEN D R ! V A BIE'U fflEN O J A C H A N
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100 ll; f " d ~ 7 i

t'd' bleu h,e" nong d'Pt' /roo Irong /0;;' 100 hiell 001
.~ aZYXWVUTSRQPONMLKJIHGFEDCBA

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100

d o ! Iro n g g ia id o o n

II/d n g

clo; m o n h

"0"9 Holo.ren

J . . i~ n t o o

c h ; 'llI ld , ; g

c o ;';

c d o m a llr ; I J I

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va

s o u , h a ,!,1 d p n g

k i i n ', ? o h i i n d q i c o

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b i ; i J h i ~ n ,! tin g d lii m o n t :

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h ir n

10m dpng

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c M ;'

10m

doi

'/p n g

" iii, 100

(0 0

~ci k '- i- 'n f ~ .

b in t. (h a p

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2.5 - 3 d o R '- c h ! e r

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C h a -n 1 0 m

va

la o

h in h c o o

d a l r e iJ

d a ; d ,? 1

d~ng

""9

d q n g e lo llr v n g

1 0 0 ': 0 ' k i l n

c /p n g

e M ;'

d o o n I a n k ir ; ,

d o l ',

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h , p n r la l

r:<
ZYXWVUTSRQPONMLKJIHGFEDCBA
.
Dv{tn.9 Jon,f/.'ri hirn iI~ .,' ; " 9 hn Inl)

£ > lI lg o 'y I h lJ ~ nv a c h n ." J n

D (J I

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d ~ R '- c h ( t r

4 ,6 - 5 .0 1 1 0 R I c h t e r

< le i d , ? 1 5 ,/ -

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d o R ic h le r

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u ...

Th

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1 1 n /< .,1 9 9 3

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can.

N guyen
(co' b o ' x u n q

D fn h
] ã

u s ô , T r a il o t i c

T h a n t;


'I'ren co sd tinh toan toc d9 tram tich tran cac doi kien true, da phan tich
moi quan h~ kien tao, chan tinh va tram tich : ngap chim khong den bu, ngap
chim co d~n bu, nang cao co tich tu va nang cao kh6ng tich tu.FEDCBA
CHUONG

V

TIl~jN HoA ZYXWVUTSRQPONMLKJIHGFEDCBA
D ~ A CHAT HOLOXEN gfedcbaZYXWVUTSRQPONMLKJIHG
vA BAN CHAT CAU
TRUC vUNG CUA SONG BACH DANG.
1. T:rEN BoA DlA CHAT vUNG CtJA SONG BACH DANG TRONG
HOLOXEN.NMLKJIHGFEDCBA
1.

Kha i

quat

tie n

hoa dja chat

vung cira s o n g

Bach D A n g tn.tae

H o lo x e n .

Trang Oligoxen - Mioxen muon, chuyen d¢ng kien tao dang khot tang
da tao nen cac kien true nang bao quanh vung v6ng ha tuong doi VCS
Blitch DAng. Sau mo t thai gian kha binh 6n, vao Plioxen muo n - D~ tti,
heat do ng kieri tao trd len manh me vdi trirong ling suat co true ne n cue
d p h a n tay nam VCS va a vi tuyen d phan dong
dai phuong a kinh tuyenaZYXWVUTSRQPONMLKJIHGFEDCBA
bac vcs. Cac dlit gay chu dao hudng TB-BN d'eu t nrot bang phai. H~ dut
gay Nui Deo - D6 Son co vai tro quan tro ng trong binh d6 chuyan d¢ng
kho'i tang hien dai. d p h a n tay nam dut gay nay, cac dut g~y hucng DB-TN
(t6 phan R') dich chuyen trai. d phan phia dong bac, M ditt gay thuan a
vi tuyen co mat trtrot hucng nam lien ke"t vdi cac dlit gay phirorig DB-TN
chuyen djch phai. S\! dich chuyeri ngiroc chfsu cua M dif t gay cung phuong
DB-TN hai be n true dtrt gay Nui Deo D6 Son da tao ra co che' tach gian
va hinh thanh ne n graben hie n dai d p h a n trung tam VCS Bach DAng.
Trang Pleixtoxen, bon trung VCS Bach Dang ton tai trong moi truong luc dia,
liing dong cac tram tich aluvi CU9icat day 30 m. Vao cuoi Pleixtoxen muon, co

mot d<;1tbi~n Ian tao nen phiic h~ tram tich chau th6 day 27 m d dia phan VCS.
Wm dong kien tao nang ke't hop voi ha chan tinh da tri~t thoro cM de>yen bi~n
va dffy lui dirong bel Wi de>s8.U100-120m ngoai cira vinh Bac B9·
2 .T ie n

hoa d ja chat vung e i ' : t as O n g Bach D A n g t r o n g H o l o x e n .

Qua trinh tien hoa lien quan chat che den biEin tien cha n tinh sau
bang M Ian cu6i tre n n e n kie'n true hinh thai duoc thietl~p t11 trudc.
Lich s· J tien hoa duo c phan thanh ba thai ky, mo i thai ky bat dau bang
bi~n tien (hoac bi~n Ian) duo ng bo Ian v'e phia luc di a va ket thiic ba ng
bi~n lu i, d u cn g b o Ian v'e phia bi~n . M6i thai ky lai dircc chia tha nh
cac giai dean. M6i giai doa n ducc dac t rung bdi su t6n tai cac ki~u mo i
t ruo ng tram
tich nhat di nh.
2.1. Thai ky thu nhat : Holoxen sdm giua (11-3 nghin nam truce). Bi~n
11


ti~n chan tinh giU vai tro chu dao gay ngap chirn, nhanh chong lam thay
t i t luc dia sang yen be, duong bo bj My lui xa nhat. Vao
doi moi truongaZYXWVUTSRQPONMLKJIHGFEDCBA
cuoi thai ky, muc nude chan tinh dang cham him, vai tro kien tao va tram
tich dU9C· tAng cuong, duong bo md Uln v'e phia bi~n, bi~n lui, .
G6m co 3 giai dean :
, - Giai doan 1 : Mo! trtrong luc dia, Holoxen som - d'au Holoxen giira. Qua
t~IDh phong hoa, xam thuc chiem iru the. Vao cuoi giai dean, bi~n tieri sat
gan gay ngap chim khu bo ngarn hien nay va phat tri~n cac moi trirong aIuvi
tich tu cat nho va moi truong h6 d'am tich tu bun set min.
- Giai doan 2 : M6i truo ng vinh - vun g yen bCJH~loxen giua : Bi~n

tie~. tr~n ~g?P' , m d :9n~ nhat va dlly lui cu da n van hca Ti'en Hq. Long
khoi cac dao. Vao nua dau giai doan to n tai ki~u m6i truong vi nh bi~n
t (bai tri'eu lay) ba i tri'eu thap va phu ki~u ran san ho. S a u
bai lay sii vegfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
thai gian 5600 narn, bi~n Iui va xuat hie n cac vung bi~n a ria phia bac
va cac de cat bi~n (M 1).
- Giai doan 3 : Moi trirong d'am fay ria chau tM cuoi Holoxen giua. Toc
d¢ dang chan tinh cham h£n so voi nang kien tao a ria vung cua song (dat
2:4 m~l/nam). Cac khu v q c : ria VCS bi nang cao, phong hoa feralit ph6 bien.
d trung tam vung cira song, nam d ria phia dong
D~m ,lay v~n bi~n t6n taiZYXWVUTSRQPONMLKJIHGFEDCBA
cua don~ Mng chau th6 song Hong Mt dau b6i tu manh. Day la thai gian
phat trien cue thinh van hoa RI,lLong, Trang Kenh.
.
2.2. Thai ky thir hai : Holoxen muo n (3 den 0,5-0,7 nghin nam truce).
Vai :ro chuyen d¢ng kien tao, d?t biet d cac ddi kieri true nang, tham gia
quyet di nh VaGqua trinh ngap chirn, n6i cao. Qua trinh tram tich tich cue
co anh huang den huang di chuyen duong boo Vao cuci thai ky, do b6i tu
manh, d~ong bo di chuyen ra phia bi~n, qua ca khu trung tam sut ha kha
manh. Gorn 3 giai doan :
- Giai doan 1 : Moi truong vinh - vung bien dau Holoxen muon. Bi~n Ian
trCill,likha nhanh. Xuat hi~n vjnh bi~n nong d trung tam VCS d~ hl,lkien tI,lo
kha ml,lnh c¢ng huang voi nfmg chan tinh cMm. Cac Vl,lngbi~n nhO t6n tI,li
a ria phia Mc tren dja pMn cac doi kien truc nang. Phat tri~n cac dl,lngmoi
truong biii trieu thap, bai trieu fay, bai bi~n va de cat bi~n (M 2).
- Giai doan 2 : Moi truong Vl,lngbi~n giua Holoxen muon. Bi~n liIi do b6i
tl,l nwnh ket h9P voi nang kien tl,lOkha ml,lnh a cac khu ~ia tren n'en chan
tinh dang cMm. Phat tri~n r¢ng rai dq.ngmoi truong bai trleu fay su v~t tich
tl,llOp bUn b9t xam xanh d?c trung va de cat bi~n (he 3).
- Giai doan 3 : Moi truong cua sOng chau tho, cu6i Holoxen muon. Muc

nuoc Mt d'au dang nhanh do ca nang chan tinh va hl,lkien t?o nh~ng q~a
12
.

trinh b6i tu kha manh do nguon cung cap b6i tich phong phu tU nguon
goc song Hong. Phat tri~n r¢ng khap bill b6i chau th6 ngap trleu cao hoa
nhap vdi chau th6 song Hong rong' Ion. Phat tri~n M de cat 4.
2.3. Thai kY thii ba: cuoi Holoxen muon (khoang 0,5 - 0,7 nghin nam qua).
Thai kY nay chi g6m mot giai dean dang tiep tuc vdi mot dot bi~n Ian mdi,
duong' bOdi chuyen ve phia luc dia, ngap chim khong den bu tram tich, xoi Ib
chiem uu the va qua trinh dam fay hoa manh me.
II. BAN CHAT CAU TRUC vUNG ClrA SONG BACH DANG.
M?c du can co nhung y kien khac nhau, nhung da so cac nha dia chat
cho rang cac estuary di~n hinh va ph6 bien thirong nam d ha hru song, co
co cau true mra kin, thuong co dang hinh pheu, bi ngap chlm (do chan
tinh va kien tao) kho ng d'en bu tram tich va thuy trfeu thuong co vai tro
quan tro ng.
Vung cira sang Bach Dang co cau true la mot estuary (cira sang hinh pheu)
dU9Chinh thanh tren co sOtirong tac giita qua trmh phat tri~n cua mot graben
dang sut chim vdi su nang cao cua mire mroc chan tinh, sir thieu hut b6i tich
va thuy trieu co bien d¢ Ion. Khang dinh nay dU9Cdira tren cac co S d :
1. Vung cira song Bach Dang co cau true mra kin do cac kien triic tan
kien tao va kien tao hien dai quy dinh. Phan trung tam cua no narn tren mot
graben sut ha kha manh trong Holoxen. Vung cira song co dang pheu, thuc
chat la t6 h9P ghep cua hai pheu Nam 'I'rieu va Yen Lap.
2. Vung ctia song Bach Dang dang a giai dean phat tri~n ngap chi m
kho ng d'en bu do thieu hut b6i tich. Trong 5-7 tram nam qua, dang chan
tinh dat 1.-1,5 mm/narn, con d b6n ha hi n trung tam ha kien tao kha manh,
0,2 - 0,8 mrn/nam. Sl1 thieu hut b6i tich chu yeu do giam nguon b6i tich
cung cap t i t song Hong va kha nang phan tan b6i tich do trfeu va huang

dong be i tich ven bo uu the DB-TN. Day cling chinh la nguye n nhan co
ban cua hien tirong xoi Id ph6 bien d viIng cua song.
3. Thuy tri'eu la yeu to d(ing I11Cngoq.i sinh uu the tM hi$n q1Jabien
dQ, toc dQ va thai gian dong tri'eu chay len xuong V.V... dftn den tang cuong
xam tht,tc va phan tan b6i tich.
4. ViIng cua sang Bl,lchD~ng la vlfCnuoc IQm?n, hoa tr9n nuoc song, bi~n
kha tot tq .o nen st,t phan fang yeu th~ hi~n qua phan bo de>ml;in.Day la dfeu
ki~n hq.n che b'oi t\1 va phat tri~n cac ba:itneu l'ay co thl1Cv~t ng~p m?n d?c
trung cho vting cua song hinh pMu.
5. D?c trung tr'am tich, dia hinh chu yeu lien quan voi tri'eu. 6 trong
so 8 tuong tr'am tich dang tich t\1 chu yeu do qua trinh tri'eu. D?c di~m
13


- zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
1-3cm/nam. T're n h(l thana' luong xay ra qua trinh sa bo i no ng d a n day
lien quan den qua trinh xam thuc ngang me ro ng luong. Sa boi lu6ng VaG
cang tang d¢t bien g a n g a n day do nhung tac d¢ng tieu cue cua con nguoi,
d~c biet la viec d~p d?p Dlnh Vu nam 1981. 'I'rudc day, lUQng nao vet
3
luong 1-2 trieu 3m /nam du duy tri lucng sau 6-7m. Hie. n nay '. Iuonz nao
vet 3-5 tr'i$u m /nam chi duy tri diroc luong sau 3,5-4m.
3. Qua trinh darn lay hoa d vitng cii'a song.
D6 la ket qua cua dang cao mire nude bi~n, ooi tu cham va su phat tri~n
day dl[l.ccua thuc vat ngap man trim nen dat uct ngap trleu cao, trong dfeu
ki~n thuy trieu bien d¢ Ion. Tren cac bill trieu fay phat tri~n rong rai d VCS,
III- Q~A TRINH DlA DONG LTJC Hr:¢N NAY d vUNG ClrA SONG
ton tai moi trircng khtr, yem khi, tfch tu hru huynh cao trong tram tich day,
BACHDA.NG.
d~ bj oxy hoa trong dieu kien kho can va thuc V?t ngap man bi chat pha .

Trim nen kien true kien tao va chuyen dong kien tao hien dai dang tiep tuc,aZYXWVUTSRQPONMLKJIHGFEDCBA
4. Tac d(mg cua con ngutri da trd tha nh mot nhan to dc)ng 11!c
d VCS Bach Db.ng dang dien ra cac qua trinh d¢ng hrc chu yeu sau :
vung cira song.
1. D(mg 11!Cdi chuye n b6i tich vung Clta song.
Tac dong nay r6 net trong khoang 500 nam qua.zCac heat dOng quai
Hoan hru b6i tich vung cua song do dong trieu quyet djnh, sau do la
de, Ian bi~n, d~p dap, ngan song, nao vet luorig, chit pha rung ngap man
vai tro cua dong chay song, s6ng. Ham hrcng, luu IUQng di chuyen bo i tich
": da d:1n den nhung thay d6i bat thuong ve b o i t4, x6i ld, gay mat can
10 hrng bien d6i thea mua va quy luat thuy trfeu. Dang chu y la hie n tuorig
\"
bang tl,! nhie n va sinh thai vung cira song.
b6i tich di ohuyan nguoc sau vao vu ng cira song trong mua kh6. Hang
IV. XU THE BIEN DONG MOl TRUONG DIA CHAT vUNG ClrA
nam c6 khoang 4 trieu tan b6i tich cung cap ur song, 2 tr ieu tan giai
SONG
BACH DANG.
.
ph6ng tl! xarn thuc bo, bai va 3-5 trieu m 3 bun cat nao vet luo ng lach
Ve lau dai, qua trinh ngap chim kho ng d'en bu c6 th~ dan den vinh hoa
tham gia vao hoan hru b o i tich trong vu ng cua song.
VCS. Qua trinh nay kho ng qua 100 nam neu du baa ve hieu ung nha kinh
2. Qua trinh x6i Id, boi t u ,
thanh sir that.
Ngap chim kho ng den bu trong dieu kien thieu hut boi ttch Ia nguyen
Trang tucng lai gan, xoi Id tiep t1.,1C
chiem iru the. Tinh toan theo quy t~c
nhan sau xa cua qua trinh xo i la d vung cira song.
Hai

tiep t1.,1C
bi x6i Id 4-6,2m/nam, dong
Bruun
(19.62,1983)
cho
thay
dao
Cat
Xet tirdng quan ooi tu, x6i la th a y rang hien nay d vung cira song qua trinh
nam Dinh Vu 0,8m/nam, cac bill bi~n D6 Son 0,36-0,45m/nam. Khu Trang Cat
x6i Id thong trio Trong do, a trung tam vung cira song, qua trinh hin chlm kien
se
b6i cham dan, cac doi cat ven luong' ngam c6 xu hucng bi pha huy va tich tu
tao co vai tro khong che. Gan day su can thiep cua con ngiroi da gay nen nhung
cat tiep tuc duoc tang cucng d ven bo duong 14. Luong VaG cang 6n dinh
bien dong bat thuong, phuc tap ve boi, x6i. Khoang 50 nam qua (1938-1992),
d a n trang thai m d i sau d?p Dinh Vil.
khu V1f.cL ach Huyen - Yen Lap lien tuc bi x6i Id, khu V1f.cC ua Cam - Nam Trieu
N gap 11.,1t
ven bo gia tang. Truye n trfeu, nhiern man tiep t1.,1C
anh huang
b6i xoi xen ke phuc tap, X6i Id d muc trieu, thap r6 va manh hen d mUc trieu
sau VaGIlJc dia. Rting ng?p m~n bi suy giam di~n tich do ca nguyen nhan
trung binh. Mbi nam vUngcl1a sOng x6i Id 37 ha, b6i t\]. 27 ha va mat di 10 ha
ttf nhien va nhan taco
bill trieu cao ; x6i Id 31,5 ha, b6i t\]. 4,5 ha va mat di 27 ha bai trleu tha'p. Toc

tich do thuy trieu chi phdi, Cac dang dja hinh tlch tu va
xarn thuc (tieu bi~u la bai trieu lay va h(l lach trieu) chii yeu lien quan
den heatgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

d o ng cua thuy trfe u .
6. Qua trinh bi~n thang the trong quan M tuong tac song bien th~ hie n
qua sir Uti,the cii a x6i ld, ngap lu t, nhie m man, dam lay hca. Theo phan
loai dOng luc cua Leeder (1984), c6 th~ xep n6 vao ki~u B e6 cau true phan
tang yeu.
Day la trtrcrig hop di~n hlnh tre n the gidi ve mot estuary phat t rieri
trong dieu kie n nhat trieu bien d¢ ldn.
phan

di tram

de>x6i Id bO diio Cat H:ii (noi h~ l~n kha m~nh) trung binh 4-8m/nam, ctfc d~
25m/nam. Bo cac bai trieu fay x6i ld 0,5-2m/nam. Noi ooi tl,lnwnh nhat la Trimg
Cat d~t den 8m/nam, c6 lien quan den d~p d~p Dinh Vu nam 1981.
d vung bo ngam, b6i t\]. m~nh d d¢ sau I-3m, d~t 1-3cm/nam. Co dau
hi$u bao man day d dO sau 5-6m. d khu bo ngam Cat Hai, baa man day
14

b

CHUONG

MOT

.

VI

s6 DE

XUAT \IE KHAI TRAc Hap LY TAl NGUYEN vA BAO vE
MOl TRUONG vUNG ClrA SC>NGBACH DANG DUOI
.

G 6c DO. NGHrEN CUD TrEN HoA DIA
. CHAT HOLOXEN
Tien hoa dia chat Holoxen, dl[l.cdi~m cau truc va dieu ki~n dia dOng
15


luc anh hunng
Dang.

quye

Van d'e khai

dua vao tc5ng hop
nhung
mo

t

d'e xuat

trong

dj nh den ban chat

t

thac

hop ly tai nguye n, baa v$ moi truong

cac dieu

kie n tir nhie n va kinh

tir dudi gee d¢ n ghie n cuu tien

nhirng

can cu rat quan

can phai

te xa ho i. Tuy nhie n,

hoa dia chat

tro ng d6i vdi khai thac,

Holoxen

quan

la

ly lanh

th6 cda song.
1. DINH
1. Dinh
Phat

CHIEN

LUOC

M61 TRUONG
huang

tri~n

khai thac

vUNG

cao nang

va khai thac nguon

yen bi~n vdi baa v~ moi truong
huang

N gan ngua

quan

HOP

LY TAl NGUYEN

BA.· CH DANG.

luc heat

lei hai san, rung

sinh

thai,

ngap man tre n co

ket hop phat

tri~n

du Itch

tu nhie n.

ly, baa v~ moi trucrig.

han cha xo i Id bo bi~n, tranh

bi~n. Baa ve, duy tri can bang
3. Dinh huang

tu nhie n va sinh thai, phong

phan vung quy hoach khai thac till nguyen

theo hai khu

II. NHUNG

bien d¢ng

tranh

a

nhie m

Vlf.C

phat

cira Cam - Nam 'I'rieu va Lach Huyen - Yen Lap.

tri~n cang va van d'e sa boi luo ng : Ban chat cau true

hudng

uu tie n kinh te cang can phai dua tre n quan di~m
han che

tr] neu hi~u r6 nguye n nhan
dung

tai nguye n bai trfeu

130 d:;tng tai nguyen

quy gia, kh6ng

a

nhiern mo i sinh. Sa boi luo ng co

va co che.

Iay, lach trieu
gia tang.

~n

can

phai co quy hoach 'hop Iy

tac d¢ng tieu cue den moi trircng.

M¢t so' di~m sa

nho kh6ng nen khai thac vi gia tang t6c d¢ xoi Id bOo
van d'e quan

bi~n, nhie m man,

ly, bao v~ moi truong

ngap II,lt, nhiern

vurig ctra song va hien trang

true

lei

130 nhung

anh d~c di~m tien hoa, cau

khai thac,

quan

ly vung cira song. Do

van de cap bach can d~t ra ve quan ly - baa v~ mo i trucng.

Cac

kinh te, dan sinh d'eu phai tinh den kha nang anh hudng

va bi

cua cac qua trrnh

III. KHUYEN

NGHl

nay.

:

Tiep can vdi no i dung dja chat
ket qua nghien
khuyeri

: Cac hie n tiro ng xdi Id bo

b:1n phan

nghi

cuu va cac quan

moi truong
di~m da trinh

va quan

ly dai yen be, ttr

b y, luan an neu met so'

:

1. Djnh hudng

phat tri~n

kinh te vung cua song 130 cang (thuong

cang)

- nuci tro ng hai san - du Itch bi~n.
van de cap bach ";e moi truong

luong ben, xoi Id bo, baa v~ rung

ngap man, nhiern Mn, ngap lut yen boo

luc vu ng cira song khi giai quyet
tr] luong

va o

nhu sa boi

hoa dia chat

van d'e nguyen

va dieu kien dia dQng

nhan

va bien phap ehinh

cang.

4. Dat ooi ngap trieu vung cira song 130 till nguyen quy, kh6ng gia tang nen
khong th~ khai thac tran Ian thieu quy hoach nhir hien nay.
5. Can co nhirng bien phap, ehinh sach quan ly moi trirong hop Iy va co hieu

nuoi trong

Do thieu

Sd khoa hQc hi~u qua cac dAm nuoi hi~n nay thap
cho nuoi quang

M co hieu qua, tranh

3. Can chu tro ng den van d'e tien

phat tri~n lau b'en moi trucrig,

cd

tich dam nuoi.

kinh te can dircc chu trong vi nhirng

kha nang hill hoa cua no vdi baa v~ t\f nhien, sinh thai.

va

2. Can quan tam den nhirng
vA

cua VCS 130 tfen d'e xac dinh tfem nang to ldn phat tri~n cum cang

Hai pho ng. Djnh

co nguy

baa v~ moi

VAN DE ZYXWVUTSRQPONMLKJIHGFEDCBA
C V THE SU D V N G HQP LY TAl NGUYEN

1. Kha nang

2 . S \i

va

M61 TRUONG.

th~ chinh

the nhieu mat

anh huang
va han che nhitng

cira song.

estuary

hop can d6i vdi dien

4. Du lich yen bien 130 mot huang

heat dong

l?p cac gie i phap ung xir. Chu tro ng hau qua cua hien ung dang cao muc

BAa vt

ra phia bi~n nsn can co ke hoach 000 ve, phuc h'oi

va can giu ty I~ thich

6. Nhung

d¢ng ciia cum cang Hai

bat thirorig ve boi xo i, dac biet 180 sa boi Iuo ng ben. Du baa cac tai bien va

truong

md Ian tu nhien

khoang

tai nguye n t6i 'uu va lau bEm.

hop ly va nang

pho n g, nuoi trong

SU DUNG
CUA S6NG

sd duy tri tai nguye n va can bang
2. Djnh

tri~n

5. Khai thac mu6i bi~n, cat xay dung d VCS

HUONG

vA BAa vt

l

tir nhie n, tai nguye n VCS Bach

hai san. Day

quy ho~ch, thieu

va tai nguyen

cd

dat Uat

lqc nh~m h:;tn che nhung tac d¢ng tieu cqc cua con nguoi.
6. Can tien
co nhung

hanh

phudng

danh

gia, d\f baa tai bien dia chat

M chuy~n huclng tMm canh thay
M tiet ki~m quy ctat, baa v~ can b~ng sinh thai va nang

vung c\ia song

M

h<;1p,kip thOi.FEDCBA

an ung xU' thich

ki~t. Can dAu tu ky thu?t
canh

cao hi~u qua kinh te.
3. Quan ly rting

K E T LU~N

1. Dqa vao d~e trung
ng?p m~n (RNM). RNM cO Y nghi:a kinh te va sinh thai

Idn d vilng c\ia song dang bi suy giam di~n tich nhanh

do quai dlip dam nu6i,

ch~t pha lay cui, do xoi Id bO, cat Ian v.v ... RNM d day khong co kha nang phat

trinh

tich tl,l va theo cau truc

(MTTT)

Holoxen

trAm tich, hinh thai bon, d¢ng lqc qua

tq nhien

VCS B~ch Dllng

M

ven bo, moi truong

duqc phan

thanh

hai phuc

trAm tieh

M (dong

b~ng ll,lc dia yen bi~n, dai yen bo), 6 ki~u (h'o - dAm ray, aluvi song, eMu
th6, estuary,

16

v'e tuang

vl,lng bi~n va vinh

yen bo), 3 phl,l ki~u (dai trfeu,

tri'eu, dai r:;tn san h6), 9 d~ng (bai boi, eMu
17

dai duai

th6 ng~p tri'eu, bai trieu

lAy,


bai trfeu thap, delta tri'eu xu6ng, de cat bi~n, bai cat bi~n, lach trfeu song,
chau th6gfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
n g a m va day vinh nho yen bo)
,
c A e T A l L 1 ~ U D A C O N G SO L IE N Q U A N D E N L U ~ N A N
2. Tien hoa dja chat vung cira song Bach DAng dien ra trong Plioxen muon
- D~ tu lien quan den truong ung xuat kien tao c6 phuong nen ep cue dai a
1. Nguyen CB:n, Nguyen Dinh Hoe, Tran Due Thanh va nnk, 1993.
kinh tu y e n a p h a n tay nam va phirong nen ep cue dai a vi tuye'n a ph'an dong
Heat
dQng dut g~y hien dai vung Hai phong-Quang yen. Trang : "I'ai
bac bon trung cira song. Qua trinh tien hoa dia chat Holoxen diroc phan-thanh
nguyen
va Moi truong bi~n". T.II. Nxb KHKT. Dang in.
ba thai ky. M6i thai k.Yb a t d'au bang bi~n tien (h o a c bi~n Ian) va Mt thiic
2. Tr'an Due Thanh, 1983. VaiaZYXWVUTSRQPONMLKJIHGFEDCBA
i kien v'e nhung bien a6i dja chat d vung
bang' bi~n.1ui. M6i thai ky lai ducc chia thanh cac giai doan ung vdi sll phat
be
Quang
yen-Hai
phong
trong

thai ky hien dai. Nhitng phat hien
yen
tri~n cac ki~u moi trirong (MT) tram tich nhat dinh.NMLKJIHGFEDCBA
mdi v'e khao c6 hoc 1983. Vi~n Khao c6 hoc. Ha ni)i.
T h f f i k y t h u n h a t : Holoxen som - giita gom ba giai dean : Giai doan
3. Tran Due Thanh va nnk, 1983. H~ thong vung cda song a ven bo
Holoxen sdm - dau Holoxen giua (MT luc dia) ; giai dean Holoxen gil1a (MT
Hai pho ng-Quang yen. Hoi nghi khoa hoc "Sli dung hop Ii tai nguyen va
vinh - vung bi~n) ; giai doan cu6i Holoxen gnra (MT dam fay ria chauZYXWVUTSRQPONMLKJIHGFEDCBA
th 6 ).
baa v~ moi trucng l'an thu I". Ha noi 11/1983. T6m tlit bao cao.
Thiri k y t h u hai : Holoxen muon, g'om ba giai dean : Giai dean d'au
4. Tran Due Thanh, Nguyen Due Cu va nnk, 1984. Vai tro ciia di'eu
Holoxen muon (MT vinh ~ vung bi~n) ; giai dean giua Holoxen muon (MT
kien
dia chat, dia mao d6i vdi su hinh thanh va phat tri~n vung ngap man
vung bi~n); giai doan cu6i Holoxen muon (MT cira song chau the).
dai
ven bo mien Blic Vi~t Nam. Tuy~n t~p "HQi thao khoa hoc v'e M sinh
a
T h f f i k y thu b a : Cu6i Holoxen muon, chi gom mot giai doan chua ket thiic,
thai rung ngap man", Ha nQi.
biit dau bang mot dot bi~n Ian moi va phat tri~n moi trirong estuary.
5. Tran Duc Th?nh va Nguyen Duc Ct!;,985.
Qua trinh hinh thanh
3. Vung cira song Bach DAng c6 him chat cau true la mot estuary (cira sang
va phat tri~n vung dat Hai pho ng. Nghien c u lich sir Hai phong. So' 2.
hinh pheu) diroc hinh thanh tren co sb tirong tac gil1a qua trinh phat tri~n mot
6. Tran Due Thanh va Phi Kim Trung, 198 . Ranh gidi Pleistocene va
graben dang sut chrm vdi su nang cao cua mire nude chan tinh, st! thieu hut

Holocene
trong tram tich day vinh Blic BQ. Nhung phat hien mdi v'e Khao
b'oi tich va thuy trieu bien di) Ion. N6 co nhirng ~c trirng co him sau : C6 cau
true mra kin do kien true kien tao quy dinh, bi ngap chim (kien tao va chan
tinh) khong den bu tram tich; thuy trieu la di)ng hrc ngoai sinh iru the, la mot
Vt!c mrdc IQ- man phan tang' yeu, a~c di~m tram tich va dia hinh chu yeu lien
quan den qua trinh trieu, bien thang the trang m6i tuong tac song bi~n. N6
phat tri~n trang dfeu kien yen bo nhiet doi co thuy trleu nhat trieu bien di) Ion.
4. Hien nay, qua trinh x6i lb thong tri d vung cira sang Bach DAng. Trang
do d trung tam vung ciia sang qua trinh hin chim kien tao co vai tro khong
che. Can bang b'oi x6i cho tMy m6i nam vung cira sang bi mat 10 ha bo bai cao,
27 ha bai trieu thap. T6c di) x6i la bO 0,5-8 m/nam, ct!c d:;ti25 m/nam. Ho:;tt
ai)ng cua con ngttai da gay ra nhl1ng oai x6i bat thttang a vUng ctta sang. N g~p
chim khOng den bU trang dieu ki~n thieu h\lt oai tich la nguyen nMn s8.u xa
cua qua trinh x6i I b b vUng ct!a sang.FEDCBA

18

c6 hoc, 1986. Vie n Khao c6 hoc, Ha noi.
7. Tran Due Thanh, 1986. Summary report on the Activities of Geological
reseach and Management of the Coastal Zone in Vietnam. A.Seminar 0;0.
"Orientation Course of Coastal Management". IOC, Netherlands. April, 1986.
8. Tran Due Thanh, 1987. Vung cira song Bach DAng. Nghien ctfu lich
st! Hai pho ng. So' 2.
9. Tr'an Duc Th~nh va Dinh Van Huy, 1987. Cac muc bi~n c6 Holoxen
a vung yen bo Dong Blic. Nhuug phat hien mdi v'e khao c6 hoc 1987. Vie n
khao c6 Ha nQi.
10. Tr'an Duc Th:;tnh, 1988. Ve st! thay d6i mllc nttdc vjnh Blic b(l trong
Holoxen. H(li nghj dia Ii toan qu6c. Ha NQi 11/1988 T6m tlit bao cao.
1l. Tran Duc Thanh, Nguyen Chu Hoi and Dinh VAn Huy, 1989.

Eastem coastal development
of Tonkin Gulf during Holoxene. Inter.
Seminar on Quar. Geo!. and Human Surviva!.october
1989. Hanoi.
12. Tr'an Duc Th?nh, i991, d~n li~u v'e dQt h? thap mt!c bi~n vao cu6i
Holoxen giua - d'au Holoxen mu<)n a vung yen b a Dong Blic Vi~t Nam. Tai
nguyen va moi trttong bi~n. NXB Khoa hQc va Ky thu~t. Ha n(li.
19


13. 'I'ran Dire Thanh, 1991. Dac di~m co ban cua cac bo tfch tu hie n
HEm bi~u a diii ven bO tay Vjnh Ba.c BQ. Tai nguye n va m6i truong
bi~n. NXB Khoa hoc va Ky thuat. Ha nQi.
14. Tran Duc Th~nh, Dinh V~n Huy va Nguyen HuugfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
ce, 1991. H~ lach
tri'eu a dai bo bi~n Hai pho ng - Quang Yen. 'I'ai nguyan va moi truong
bi~n. NXB Khoa hoc va Ky thuat. Ha nQi.
15. Tran Due Thanh va Nnk 1991. Hinh thai, clu true va tie'n hoa cac
bai trleu Illy ven bo phia bac Vi~t Nam HQi nghi khoa hoc to a n q u o c v~
bi~n Ian III. Ha n¢i 1l/199~. Tom ta.t bao cao.
16. 'I'ran Due Thanh va Nguyen Chu Ho i 1992. M6i truong dia chat va
van de sa b6i cang Hai phorig. Hoat d9ng khoa hoc ky thuat. UBKH va
KT nha nude No4
17. Tran Due Thanh et all, 1992. Current status and causes of erosion
in Cat Hal Island of Haiphong Proc. Regionnal seminar on Env. Geol. Ha
noi.
dai

18. Tran Due 'I'hanh, Nguyen Chu ff6i va Nguyen Difc Cq1993. Co sa
khoa hQC sa dung hop ly cac bai trieu Illy ven bi~n phia bac Vi~t Nam.

Tuyen t~p "HQi thao q u o c gia nghie n cuu va q u a n ly vung ven bi~n Vi~t
nam" Vi~n KHVN - ro c Vi~t Nam. Ha NQi.
19. 'I'ran Due Thanh, 1993. Cac phuc M sinh thai tao silic (Diatorneae)
trong tram tich D~ tu vung trfe u Hai Phong - Quang Yen. Tap chi Khoa
hoc. DHTH Ha noi, No.1.