Hình thái địa hình và trầm tích hiện đại vùng biển ven đảo bạch long vỹ tuyển tập tài nguyên và môi trường biển, tập 3, tr 27 35

T iii

M t)C

nguyen

v ii M { ji

KJIHGFEDCBA
tr u ir n g b ie n . T ( lp

/1 /

-

ZYXWVUTSRQ
/9 9 6

L t)C

T ra n g
1.

L (~ i n o i d a u

2.

D ac

d ie m

v in h

B ac

5
th a i

h in h

D ia

C hu

H in h

th a i

B ach

Long

T am

S O n , D illh

tra m

va

T am

Ve

d ie m

L li I l

T r a il

D L lC

dai

vung

b ie n

yen

T h ( llllz

dao

27

m oi

G ia n g

D in li

L tin ,

D in li

tra m

tru o n g

- Cau

nguon

cung

V a ll

tic h

H uy,

Due

h ie n

N guyhi

T lu ] lz lz ,

dai

de

cap

th e m

cn«

N guyen

dam

tu a « ,

Q U W lf (

H (;i

pha
36

H ai

- C au

G ia n g

van

D in h

H uy,

va

H ai

su

phan

Lan,

D illiz

cu«
ta n

H 6 i,

tra m

T r a il

N guyen

tic h

b ie n

Due

T I z ( I I lI z ,

Q uang

h ie n

dai

tu a «

(~ p h a

(H u e )

45
N guyen

7.

T ra n

V illl

h ie n

tic h

N g u y e ll

C ac

T N ( [ I l,

16

T r a il

6.

day

tic h

so

T r a il

D ac

tra m

Vy

tr a «
5.

tro n g

Q uang

~N g u y e n

Thanh

h in h

d ia

Hoi

B ac

v in h

N guyen

4.

soi

h < '1 c u o i ,

7 WVUTSRQPO

day

h in h

phan

Bo
N f ( u y e ll

3.

va

ky D ~

tro n g

Tu

() V ie t

N am

Q uang
(p h a n

T w ill

lu c

55

d ja )
N guyen

8.

V ai
trie u

tro

cua

khu

k ie n

V \jC

ta o

yen

h ie n

h ie n

dai

tro n g

su

h in h

D tl S o n -H o n g

Hoan,

th a n h

N guyen

dat

V6

phong

hoa

tre n

dao

B ach

Long
N g u y e ll

uot

68
D in li

H oe
80

Vy
DUe

.

ngap

G ai
N g u y e ll

Y.

N goc

cu.

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nau

01

337

M 6 i ZYXWVUTSRQPONMLKJIHGFEDCBA
t r u i r n g h ie'n . T (ip II/ - vutsrqponmlkjihg
/996

T iii n g u yen va

THAI DIA HINH ZYXWVUTSRQPONMLKJIHGFEDCBA
v A TRAM TicH Hlt::N D~I VUNG

HINH

VEN DAO B~CH

LONG

vi

T riin D in h t.a « ; D in h
N g u y in

Dao Bach

Long

Q uang

T u fin , T riin D u :« T h a n h , N g u y ln

Vi narn c) trung

BIEN

V a ll H u y,

C hu H O i

tarn vinh Bac BO co toa d¢ dja

ly

tit

20°07'35" den 20°08'38" B, 107°42'20" den 107°44'15" D vdi d ie n tich p h a n
ndi la 2,5 km2; phan chiu anh huong trieu va day bien den d¢ sau 5m la
khoang 4,2km2. De co. co sd cho viec nghien CUll d;)c diem hinh thai, quy
bci tu - xoi It) phuc vu cho quan Iy va bao v~ dao lien quem su dung
Iy tai nguyen, bao ve moi truong phuc vu phat trien kinh te xa hoi
huong IflU ben, nhung net co ban ve dia hinh va tram tich hien dai
bien yen dao se duoc trinh bay trong bai viet nay.

luat
hop
then
vung

Nguon
10/1995

Uti lieu

do Phan

can su dung

'My

chu

yeu

tit hai dt;1t khao

vien Hai Duong

sat thang

hoc tai Hai Phong

cac ban do, hai do xufit

bantheo

7/1993

thuc

hien.

va thang
Ngoai

ra

cac narn cua Vi~t Nam va

cac an pharn dft xu at ban c6 lien quan. Cac p h u o n g phap k h a o sat
bien then quy p h a m n g h ie n c u u bien 1981 del d u o c a p d u n g v o i viec s u
d u n g c a c th ie t
b ] d jn h
vi v e tinh, do s a u h o i am, Ia n ngarn v o i th ie t b ]
SCUBA. Phuong phap phan tich C(1 hoc, khoang v~t tuan theo quy pharn
tren. Phan i'c;~i tram tich then .U~ itzin [3].
va

I. -D~C DIEM

DJA HiNH

Oc10 B a c h Long Vi narn trong khoang
60m

tr e n

m ot

k

hu

nang

giua hai d u o n g d5ng sau 30m va

cao c6 d ie n tich chirng

1500 km2 chiern

khoang

J/l () dien tich day Vinh Bac B(). 0 pharn vi hep hon, dao narn trong

mot

bang d5ng th u o c d do s a u 30-40m, d ie n tieh k h o a n g 500 km2, g6c doc
khoang 5'. Tit dO sau 25m tr<'l le n tr en, suon bo ngarn dao tr<'l nen rat doc
ndi lien vung trieu va phan dao nrii.

. dong

Phan

dao noi co hinh dang mot dl)i thap

c6 huong

keo dai dong bac -

nam voi dinh cao nhtit dat 61,5m, be mat dinh doi tuong doi bang

phang. Theo Saurin (1956) nhan xet thi day la 'phan sot. cua be mat xarn
thuc - b6c man. Mot so nguoi khac lai cho rang day la mot them bien [6].
Qua khao sat thay rang day c6 le la dau tich mot bac them co. SW)n doi
rat doc voi g6e doc dat 25-30°, khong xuat hien cac muong x6i. 0 khoang
ta y

27


T a ! n g u yen

va

M 6 i ZYXWVUTSRQPONMLKJIHGFEDCBA
tru o n g
h itn . T ( i p III -vutsrqponmlkjihgfedcbaZYXWVUTSRQPON
1996

dQ cao 10-20 m cua suon dai xutit hien cac tichfu
phong thanh voi hai
dang co ban : dang c6 cau tao lap day suon trung voi cac loai oat nau xam
b o t, be day d u doan 3-4m; dang rich tu go dun cat p h a n ba di~n hinh
Ian itZYXWVUTSRQPONMLKJIHGFEDCBA
d mui ta y nam dao d IU tao boi cat nho, cat trung yang nhat. Chan dai xuat
hien cac them bien cao lO-ISm va 4-6m. Them 1 0 : lS m
cau tao tv cuoi,
soi, cat, set yang loang 1 0 Ian cac sari pharn phong h6a laterit day O , S - lm ,
tudi Pleixtoxen muon. Them 4-6m cau tao tv cat, san, cuoi da gdc Ian nhieu
vo than mern bien, tudi Holoxen giua [2].'

Bo dao gorn 3 doan co ban: bo nam c6

huong

dong - ta y dai 1,5km, bo

dong c6 huong dong bac - nam tay nam dai 2 km va bo tay c6 huong

dong

bac - tay nam dai 3 km hQP thanh mot tarn giac c6 chu vi 6,5km. 0 bo dao
kha phd bien cac them mai man hien dai, chu yeu la them da gdc, doi cho .
rat rong, mot phan nho cau tao tv cac khoi tang co kich thuoc 0,1-1m.
Rieng 0 doan bo narn-dao, cac bai cat thanhphan
cat trung, cat nho Ian
n h ie u m a n h v u n

than

rnern chiern

uu

the ruyet doi. N g o a i ra con c6 mot

so de cuoi ph an be 0 mom dong bac va rai rac quanh dao
dung cao 1- 1 , S m hinh thanh then mua do bai bi xoi 10.

c6 cac vach

Vung trieu quanh dao co be rong thay doi tv vai chuc den vai tram met,
dien tich tong cong k h o a n g 1,2 km2. Cac be m a t 10 da gdc kha p h o bien 0
phia dong, thanh phan da gdc la cac loai cat ket, bot ket, soi - cuoi ket phan
lop tv vai cm den vai chuc cm voi duong phuong dong bac - tay nam, tudi D~
.Tarn [S ]. Cat ngang qua cac lop nay la cac khe nut duoc lap day bang tram
tich cat da bien chat tao ra cac "th~ tuong" day den 25cm va keo dai xuong
phan ngam. Rai rac tren toan vung trieu la cac khdi tang thanh phan la da
goc cua dao, kich thuoc co khi den 1m hoac hon. 0 vung trieu nam va tay
nam dao kha phd bien cac tich tu cuoi, soi tao thanh bai. Cac .bai cuoi phia
nam dao c6 thanh phan da gee, mai tron tot, trong khi d6 cac bai cuoi - soi
- cat 0 mom tay nam dao th a n h p h a n chu yeu lai la rnanh v u n sinh v{tt.
Suon bo ngam quanh dao dat den dQ sau 10m (xap xi 2 ta n dQ cao
s6ng), chu yeu lQ da goc th a n h p h a n gidng nhu 0 vung trieu. Dac diem
ran nhu 0
dang chu y 0 day la su phat trien cua san ho, c6 noitaothanh
rnra bac cua suon bo tay dao d~t dQ phu 60-70%, cac noi khac san ho phat
trien thua hon, d() p h u th a p duoi 50%. Tron"g pharn vi suon bo ngarn cung
xuat hien 2 them mai man bi ngap chim: them sau 2-5m c6 gee doc 1-2°,
phan sat vung trieu c6 nhieu bai ngarn va mom da; them sau 7-10m c6 be
mat kha bang phang, goc doc < ] 0 , c6 noi rong den gan 1 km (phia nam
dao). Chua xac dinh tudi cua 2 them nay.
28

•


T a i n g u yen vii M oi ZYXWVUTSRQPONMLKJIHGFEDCBA
t r u i r n g b ien . T (L p /II - vutsrqponmlkjihgf
1996

Vung bien ven dao (tit 10m tro xuring) the hien r6 hai phan. Phan tir
dO sau 10-30m, la mot suon co kha doc, dlu tao chu yeu tir vat lieu V\In
tho (cuoi, san, cat), lac dac phat trien san ZYXWVUTSRQPONMLKJIHGFEDCBA
h o sung va co bien. Phan d dO
sau ngoai 30m ndi lien dong bang day bien .co cac dia hinh am va duong
phan bo tuong d6i dieu hoa gom: dia hinh duong la cac duong bo co, doi
da gdc sot cao tuong doi 5-lOm p h u cat, dia hinh am la cac thung lung
song co c6 huong tay bac - dong nam va cac diem 10 da goc D~ Tam [5].
II. D~C DIEM TRAM Tic"

Tram

"le N

DAI

tich hien dai duoc khao sat trong pharn vi

cho den do sau 20m vdi hai phan
trieu va day bien ven dao.

c6 nhung
.

tv

dac trung

muc trieu
tram

cao nhjit

tich rie ng: ddi

Tram tich ddi .trieu gorn hai loai tram tich vun tho luc nguyen
tich vun tho cacbonat sinh v~t ph an bo xen ke nhau.

va tram

Tram .tich vun tho luc nguyen gom cac IOC;litang, cuoi phan ho tap trung
d ven bo nam dao, phan lon trong pham vi hai trieu thtip. Bai tang co dien
tich khoang
1000 m2 nam ve phia fay dao voi tang co k ich thudc t ir
100-1000mm,

t(lp trung

trong k h o a n g 500-1000mm.

tang Ian k h o n g tap

Cac

trung thanh bai thuong co kich thuoc 100-500mm. Thanh phan thach h0C
tang chinh la thanh phan d a g d c nhung phd bien I'a tang cat ket. Cac bai
cuoi d bai trieu

thfip phia nam va mom dong bac

kich thuoc 50-100inm, mai tron rat tot, thanh
ket, bot ket, cuoi ket ..

&10

phan

eh u yeu la cuoi det,

thach

hoc la da goe cat

Tram rich cachonat
sinh vat gorn cac IOC;lico kich th u o c tu c u o i nho
(1O-50mm)
den
cat,
phan
b6 chu yeu d bai tuong ung muc trieu trung binh V~I
,
can phia nam dao, mom ta y nam dao va cac d e cuoi () morn dong bac dao.
Bai soi san (gravels)
thuong hep (rong khong qua 10m) phan b6 d doi
chuyen tiep giua bai cuoi va bai cat d phia nam dao, bai rong nhat dat
72m <1 morn tay nam dao. Thanh phan cuoi nho va s{· )isan thuong la manh
san h6 chet, manh than mern, phan rat nho khac la rnanh
dao trung cua soi san duoc cho d bang 1.

da goc. MOt so

Cat cacbonat tap trung d cac bai phia nam dao vdi be rong
30- 70m. Ngoai ra can co cac bai nho dai 80-100m, rong 20-30m
bd dong dao. Cat tho va cat trungIa
hai thanh phan chinh
(bang I ) voi thanh phan thach h9C va khoang v~t nhu sau: vo
chiem

tir 55,67-99,25%

gorn manh

vun san ho, than

thay doi tir
d cung 10m
cua cac bai
voi sinh v~t

mern va Foraminifera'

29


T a i n g u yen ZYXWVUTSRQPONMLKJIHGFEDCBA
v a M 6 i t r u i r n g b ie n . . T ( l p III -vutsrqponmlkjihgfedcbaZYXWVUTSRQPONM
1996

Jam

20

T h em h ie/! 1 0 - t5 m
fa

""'~ ...,....c

b ie n 4 -o rn ZYXWVUTSRQPONMLKJIHGFED
T h em n > a i 'r n o n

lhem

."'2'<.

" ::--" = < " ,~ ;;::.,-

Them

m .iim u n f l9 ; f p c h lm 2 -5 m
lh iin m .iim u n
.? g ;J " p ch i7 n .7 -tO m

.O O m

Hinh 1. So db mat cat dia hinh dao Bach Long Vi.

'

~~~om
8 tf N a m

Hinh

30

2. So db cac mat cat vung bien ven bi> thco bang do sau hbi am,


7 iii

n g u y e n v ii M {ii tru irn g

(co khi chiern den 45%); thach anh 0,05· 39,10%;
manh dft 0,50-21 ,R 5 % . Khoang v~lt nang co tuamalin,
rutin,

b ie n .

T t)p III • 1 9 9 6 vutsrqponml

sat laterit 0,02-1,74%;
ilmenit, zircon, epidot,

voi tong ham luong rat nho, chi d~tZYXWVUTSRQPONMLKJIHGFEDCBA
< 1 %.ZYXWVUTSRQPONMLKJIHGFE

hoeblen

I.

Bung

Mc)t s6 di)c trung

tram

tich vung bien ven d~io Bach Long

Gavels
Md

Vung tri~u
lay va nam

Cat Ion-cat

----,

Khu vue

----

I

Vy.

So

--

Md

Sk

Irung

--.--r---!

So

Sk

--

iI

1,36-2,721

1,6-2,1

0,4-0,9

0,35 1-0,795

1,3-1,7

0,9-1,3

dao
Day biC!n

ta y

va nam

1,05-1,31

1,6-2,2

0,9-1,1

dao
Tram rich day bien yen dao tich tu 0 cac cho lorn hoac gb tao ra b c i
da gric voi dien tich co dO phu > 50% rat han che. Con phan Ion dien .ich
day bien 1 < ) da g d c hoac duoc phu hili san ho song. Thanh phan tram uch
bb roi the hien uu the tuyet doi cua cac vun tho eacbonat vdi rnanh vun
Cac loai cuoi - soi - san phu tren da
san ho, than mern va Foraminifera.
g6e voi dO phu > 50% phan b6 0 hai vung cang phia narn dao. Thanh phan
soi, san chiern uu the tao ra cac song cat ngarn co buck song 30-40 ern, cao
10-15 ern h o p thanh mot h¢ thong don di~u co huong 330-360°. C u o i - soi
- san - cat phu tren da g6e voi de) phu <50% p h d bien d nhung phan con
lai toi de) sau 1O-15m. 6 do sau Ion hon (toi 20-25m) phan b6 C{lCloai cat
- s~n soi tao thanh dai vien quanh dao noi tiep dai tram tich soi - san cat trong vjnh Bac BO, rna ,0 dai nay soi san co kich thuoc tu 1-5mm thanh
phan chu yeu la Celt ket, da voi, acgilit va quaczit; cat la nhung di tich cua
cac the h¢ duong bo co 0 day vinh [1]. Dai tram tich nay phan dj min dun
tir trung tam ra phia ngoai voi cac tich tu vun tho (soi, san, cat Ion, cat
trung) la tram tich di tich Pleixtoxen,
co tudi Holoxen [4].
III.

B I~ N tx )N G

cA e

con cac tram

D ~ e T R U N G T R A M T ic H

tich min hon (cat nho)

e U N G B O P H iA N A M D A O

Day la cung hil nhay earn nhtit d6i voi nhung

bien doi cua dieu

kien
31


T a i n g u ye n va

dong
phan

M 6i

b ie n .

t r u im g

T (L p

/ 9 9 6 vutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF

III·

luc vung bien. Phan tich nhung bien dong ve co hoc tram tich gap
lam sang to cac yeu to dong luc tac dong qua tr inh bien doi bo va

bai cua dao.
Tuy ZYXWVUTSRQPONMLKJIHGFEDCBA
c h u a x a c d in h dUQC day d u be day lop tram

tich, n h u n g co the de

dang n h a n thay tinh p h a n lop tram tich lu a n p h ie n n h u sau: lo p tr e n d IU
tao boi cat IOn - cat trung chua vo sinh vat, mau yang, day tv va i em den
22cm; lop duoi cau tao tv soi san, thanh phan chu yeu UI manh vun eacbonat
cua san ho, than mern va Foraminifera,
Su

ke luan
p h ie n c u a hai lop
nay d phan
bai
trieu cao mau hon

be day thay ddi tv vai em den 50cm.

xen

- - - - - f o r · , u 'J 5 '
-------2 0 ·

_______

_______

o

"""" ""

xudng
thap,
ke

phan
s6

lop

giarn

o ()

bai
xen

di

va

dao.

S\1

C u !d lJ ~ n h p ;'Ih tJ '.l!1 o ;
r:
-'
< lI '"

' ••••

o N yels m .Jn h w rr

ffl3 0 h

.L

y u n C 3 C o D l7 < 7 !

C J /fm - c .it

C O IC D O n ,d ---------

/ru n g

Cvoi·sOt-.swn ",.nh crt1uoc4a••••m ""--"

51"'! Yl,;ri.o/1hJ,

< 5Q %

__

_

C V O I - S l J / " " S < l n l 1 1 > 7 n h C i 1 c D _' (_
J .{.a o e t~

lop, n h u n g be day
moi lop lai tang.
Xu the nay c u n g
xay
ra
d
mom
dong nam v a tay
nam

09'

----------~
--------------~

",n g lh .in h p h ii"I.{g /ji:

-o Q -0

. '. .'. : . :

IOn chi con 2

phan

0

5,,.

150 300m

nhung be day tung
lop m o n g di. Cang

gfedcbaZY

xen

ke luan p h ie n nay
the

hien

nang

cac m uc

lu o n g

h o at

dong cua song ket
hQP cac muc trieu
d khu vue.
Theo

mat

cat

ngang bai, mau v~t ~-----------------------20'

da dUQC th u th~ p J f;= = = = = = -= -= ·= -= --= --= --= --= --= -·-= --= ------~ --------------------------_ -_ -_ -_ -_
tren mot mat cat '--_ fO 'r.......:'# ..:...:'O -'-s ·
kha

dien

vung cang

hinh

d

nam
thuoc b o nam dao
voi cac muc trieu

32

ta y

HinhJ.

So

db p h a n b6 tram

r ic h

dao Bach Long

h ie n

Vy.

dai vung bj~n

..J


T a in g u y e n

tit 4,Om, 2,9m,

1,4m den

1,lm/Om

va M 6i

tr u im g

b ie n .

hai do. Ve mua gio dong

T~p

/1/ •vutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJI
/996

bac, bien doi

thanh phan va cac d~c trung tram tich cho thay cac hat cat (0, 1-lmm) giarn
dan tit 96% (tai vi tri 4,Om) xudng 25% (1,4m) roi lai tang len den 65% 6
phan thap hon (1,1 m). Cac thong 56 d~c trung: Md the hien tang dan tv
O,268-2,72mm
theo chieu giarn do cao cua cac vi tri th'u mllU tit 4m den
1,4m, sau do lai giarn di 6 cac vi tri thap

hon (1,1m).

Tri 56 So cung the

hien xu huong

tv Md tuc la chon loc kern dan trong
tuong gfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

va iai tot dan

khi xuring cac phan

thap

khoang

hon cua bai. Nhu

4m-1 ,4m

vay, tai vi tri

tuong ung do cao 1,4m cua bai co su thay doi ve cac dac trung tram
tich, dieu nay cho phep suy lu~n ding day co the la diem pha n gioi giua
xoi 16 va ht)i t u bfii ve mua gio dong bac. Nhin chung tren toa n mat cat
thi xu the tram

tichtho

da n tv phan

cao xudng

phan

thap

cua ba ZYXWVUTSRQPONMLKJIHGFEDCBA
i.

D9C theo cung b~ nay, trong khoang do cao 2,6-3m/Om hai do' tu dong
sang tay, cac thong so dac trung cho phan hu tram tich bien doi nhu sau:
Md tang dan tit khoang giua cung bo ve hai phia. So co xu huong giarn dan
tit dong sang tay, nrc la chon loc t6t dan theo huong nay. Nhu vay, ve rnua
gio dong hac co the noi nang luong song t~p trung cao hon 6 hai dtlu cua
cung bo. Xu the di chuyen
Nhung bien
l~p lai mat cat
nam narn i 993
trung tram tich
trj Md hau het
gia tri Md
b

ac

tram tich de tich tu van phan giua cua cung bo.

dong theo mua cung the hien kha r6. Tren co so khao sat
6 vung cang phia tay cua bo nam vao dau mua gio dong
va dau mua gio dong bac narn 1995, bien dong cac dac
theo mua dU~1Cghi nhan la: vao dau mua gio dong na m gia
narn trong khoang O,220· 0,437mm, vao dau mua gio dong
bien doi trong khoang O,612-2,72mm. Tram tich duoc chon

19c theo huong nguoc nhau, vao dau rnua glo dong nam, tram tich chon
19C t6t dan tit phan cao xuong phan thap cua bai; vao dtlu mua gi6 dong

bac thi xu t.he nguoc lai.
bo
tai
tao
san

Nhu vay qua khao sat thuc te va nghien cuu thanh phan tram tich, phan
tram tich 6 khu vue, r6 rang vat lieu tram tich hien dai co nguon gac
cho Ja chinh voi cac nguon cung cap tv: da gOc va them bien hien dai
ra cac tram rich chu yeu hat tho nhu cuoi tang; sinh v~t rna chu yeu la
ho, than mem va Foraminifera
tao ra cac loai tram tich cuoi, soi, san,

cat. Su tich tu cac tram

tich vun tho tit cat trung

den cuoi tang 6 doi trieu

ma dac biet la 6 cac mom nho cua dao chi tich tu cuoi soi den cuoi tang
cho th a y day la nhung doi rat dong, nhay earn voi nhung thay doi theo mua
va bat thuong.
3- TNSVB

Song va dong song ket h o p giao dong rnuc nuoc trieu la cac

33


7 a i n g u yen va M 6 i tru irn g h iln .

nhan

toc dong

luc chinh

T ~ p 1 // - vutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCB
1996

trong

qua trinh

tich tu tram

tich. Qua

trinh

tich

tu ngarn d day bien ven dao (chu yeu d phia ray bac dao va phia nam dao)

gcn
xay ra duoi anh huong cua song va dong chay ven dao. Cac diu tao ZYXWVUTSRQ
song ngam d dO sau S-7 m phia nam dao cluing to tac dong di chuyen

ngang cua song, d~c biet khi bien dong thi vai tro cua song cang Ion. Tuy
nhien cac tich tu ngarn hien nay moi chi xay ra d cac hdc hoac cac gd da

g6c rria chua lien ket duoc cac v~t lieu tho (tang) san co.
.
IV . K £ T L U ~ N

Bach Long
doi khoang

Vy

la mot qua doi co dO can tuyet doi 61,Sm, d(l cao tuong

90m, nho len tit be mat dong, bang day hien d dO sau khoang

30m. M~t dinh doi kha hang phang va co le la dau rich cua mot bac them
co, tren suon doi co cac them tich tu bien d d(l cao lO-ISm va 4-6m. Cac
them mai man nam ngang muc nuoc trieu hien dai va (1 d(l sau 2-Sm, 7-10m.
Trong s6 do, them mai man hien dai narn ngang muc nuoc trieu rat rong
va hiern thfiy. DO doc suon Ion nhat trong khoang d() cao lS-40m va d(l
sau 1O-2Sm. Huang keo dai cua dai co ban trung duong
da gdc. San he) tao ran phat trien b d(l sau 2-15m.
Tram

tich hien

phuong

cac lop

dai vung bien ven bd gom co nhorn vun tho va nhom

ngubn gdc sinh v<}t (san ho, than rnern ... ). Nhorn vun the) gorn tram tich luc
n~uyen co nguon goc chu yell tit pha h u y bo dao, thanh phan tang cuoi va
phan h6 c:~ddi trieu. Tram tich vun the) cacbonat thanh phan cuoi, soi, san, cat
co nguon goc pha huy va tai lang dong tit tram tich sinh vat, phan bo tit
ddi trfeu cho den d(l sau 1O-15m, phu thanh lop mong khong lien t\1C tren
be mat nen da guc va tap trung b phia nam va ta y bat dao. Tit dQ sau
25-30m

tro ra, cat luc nguyen

chiern uu the.

Tram tich bai hien dai chu yeu la cuci, san, cat 'cacbonat, phan bo tap
trung d phia narn, co thanh phan co hoc rat thay d(li theo mat cat dja tang,
mat cat ngang bai, dQC cung bo va bien d6i theo mila gio, ph an anh su thay
doi tuong

quan

TAl LIEU
1. Nguyen

Chu

boi - xoi do dong luc song theo mila.
THAM

KHAO

Hoi, Nguyen

Quang

Than, 1994.

Sc1 bo tram tich mat day Vinh Bac BQ. Tai nguyen va Moi truong
T.l1. Nxb. KHKT Ha NOi. trang 96 - 102.
2. Nguyen

34

Chu

Hoi, Tran I>llc Thanh,

.

1>6 C6ng Thung,

1995.

bien.


T u ; n g u yen

vu M 6 i tru irn g

b ien .

- vutsrqponmlkjihgfed
/996

T ~ p II/

Bao cao khoa h9C thuoc de tai "Dieu tra danh gift dieu kien tv nhien
va tai nguyen vung hien quanh dao Bach Long Yy phuc vu mot so nhiern
vu kinh te - xa h(>i dip bach va ph at trien
Hai Duong

Hiu hen". Luu tai Phan

vien

H9C tai Hai Phong.

3. Lisitzin. A.P., 1986.

Principles
in marine

of geological mapping
science, No.37.

of marine

sediments.

UNESCO

report

4. Tran f)(fc Th~nh, 1995.

Ranh gioi duoi va dia tang tram tich Holoxen d them
B(>. Tap chi Cac khoa hoc trai dat s() 1 trang 22-30.

luc dia Vinh Bac

5. Trim Van Trj va nnk, 1977.

Dia chat

Yy.

dao Bach Long

Tap chi Dia chat s() 132, trang

1-11.

6. f>O Thyet va nnk, 1977.

Dja chat dao Bach Long Yy, Ve su co matZYXWVUTSRQPONMLKJIHGFEDCBA
c u a cac them hien () Bach
Long Yy. Tap chi Dia chat so 127, trang 15-17.
SUMMARY
MORPHOLO(;Y

AND RECENT SEDIMENTS IN THE SEA AREA AROUND THE

BACH LONG VY ISLAND
Tran Oinh Lan, Dinh Van Huy, Nguyen Quang Than,
Tran Duc Thanh, Nguyen Chu Hoi

T h e B a ch L o n g
a n d N E -S W
T h ere a re
B en ch es

V.V

isla n d - a h ill w ith th e ra th er [la t to p o f 6 1 ,5 m h ig h

o rien ta tio n -ro se

IW O

a ccu m u la tive

a re fo u n d

co ver a n a rea fro m

m a rin e

fo rm a tio n s

d eep .

terra ces a t 1 0 -1 5 m a n d a t 4 -6 m

h ig h .

V y sea b o tto m co n sist o f tw o types
o f th e B a ch L o n g ZYXWVUTSRQPONMLKJIHGFEDCBA

b o u n d e rs ;

o n th e

at about 30m

2 -1 5 m d eep .

sed im en ts
of

p la in

1 5 -4 0 m in h ill h eig h t a n d a t 1 0 -2 5 m in d ep th . C o ra ls

su ch a s terrig en o u s sed im en ts
co m p o se

a sea b o tto m

a t litto ra l a n d a t 2 -5 m a n d 7 -1 0 m in d ep th . T h e stro n g ly

steep slo p es a re n o ted a t

R ecen t

fro m

a n d ca rb o n ifero u s

p eb b s

isla n d .

and

tra vels

C a rb o n ifero u s

o n es. T errig en o u s sed im en ts

d erived
sed im en ts

co ra ls, m o llu scs

fro m

th e

h a ve

co m p o n en ts

and

ero sio n

of
of

g ra vels a n d sa n d s

o rig in a ted fro m

sp a tia l d istrib u tio n

o f sed im en ts is reco rd ed o n th e so u th ern p a rt o f th e isla ;ld

[r o r a m in ife r s .

The

sea p a ri w ith th e co vera g e h ig h er th a n 5 0 % . O n th e rest, th e sed im en t co vera g e
is less th a n 5 0 % a n d b ed ro ck exp o su re is co m m o n .

In a d d itio n ,

ch a n g es o f

35

T a ; n g u y e n v a M 6 i ZYXWVUTSRQPONMLKJIHGFEDCBA
t r u i m g b ie n . T ~ p III - vutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
1996

sed im en t
so u th e rn

d istrib u tio n p a ra m eters su ch a s M d a n d S o a re a lso stu d ie d
co a st

tra n sp o rta tio n a l

of

th e

d yn a m ics

isla n d

in

o rd er

to

co n sid er

o n th e

d ep o sitio n a l

and

o f sed im en ts. ZYXWVUTSRQPONMLKJIHGFEDCBA

*
*

*

D~C

DI~M

MOl TRlfONG

TRAM TICR

DAM PHA TAM GIANG

D in h '

N g u y ln C h u

MO

D~I

- CAU HAl

T riin

I.

HI~N

L d n , T ra il

H o i,

Due

Thanh,

N g u y in Q u a n g T u iin

DAU

Dam pha Tam Giang - C a u Hai (DPTGCH)
la mot h¢ tv nhien yen hi)
hoan chinh, co nhung d{lc trung rieng ve Itch su hinh thanh, qua trinh phat
trien

va suy tan.

Cho den

nay, DPTGCH

n g h ie n c u u c o b a n c u n g n h u

truong
diu

irng

la mot trong

dung quan

19

diem

cho nhung

la u b e n ta i n g u y e n v a m o i

cac thuy vue yen bo Vi¢t Nam. Cac dac diem ve dieu kien tu nhien,

true he, cac qua trinh

dien ra trong -he

va

co anh huong

dia chat, vat 19 thuy van, thuy hoa va sinh h9C ... da va dang

sang to nho cac cong trinh nghien cUU gan d a y co su phdi
Mot trong nhung van de co quan h e chat che voi cac qua
la moi truong tram tich hien dai ma cac dac trung co ban
bay trong bai viet nay.
Nguon

dell he nhu

duoc dan dan
hop da nganh.
tr inh dam pha
se duoc tr inh

tai lieu chu y e u cua bai viet dua tren cac s6 lieu khao sat, phan

tich, danh gifl cua cac de tai cap nha nuoc "Su d u n g hop 19 cac h¢ sinh thai
tieu bieu v u n g bien ven bo Vi¢t Nam" v a "Nghien c u u khai thac va su d\:1I1g
hop 19 tiern nang

pha Tam Giang"

do Phan

vien Hai Duong

H9C tai Hai

Phong chu trl trong giai doan 1990-1996. Ngoai ra con su dung mot so tai
lieu da cong h o [1--12]. Phuong phap nghien cuu tram tich bien hien dai .
baa gorn thu thap mau vat, phan tich va xu 19 so lieu ve co hoc tram tich,

khoang vat, dja hoa moi truong ... dua thee quy .pharn dieu tra nghien cuu

36