^
Tap chi DIA CHAT. Innt A. s6 329. 1.2J?0I2. lrJO-36
VE TAP DOLOMIT THUOC PHAN THAP NHAT CIIA HE TANG DONG GIAO 6 TAY BAC BO
NGUYEN DINH HUU', DAO THANH HUONG^
'Hoi Co sinh Dia idng l-,et Nam. Hi, Ngi ' Viin Khoa hoc Dia chdt va Khodng san. ThanhXudn. HdNdi
Tdm Idt: Trong bdl bdo ndy. cdc ldc gid dd md ta mgt sd mgt cdt trong phdn du&i he Idng Ddng Giao (Tia dg). ddng ihdi di nghi ggi nhung lap dolomit lot day cita hi tdng Id "tap dolomit PbS Nggc". Nhirng tdi liiu mdi vi thgch dia long ndy cdng chung Id rdng vdo cudi ky Olenek - ddu ky Anisi a Tdy- Bdc Bg dd xdy ra nhdng thay ddi ve diiu kien cd dia ly di thdnh lao nen tap dolomit Pha Nggc vda Anisi sdm.
H e tang D o n g G i a o d u g c Z h a m o i d a A. va P h a m V a n Q u a n g [1] x a c lap t r e n CO so mat cat tir Co Dam, vugt qua day nui Tam Diep din Dong Giao voi tuii ban dau la Ladin. He ling phan b i rit rgng rai 6 Tay Bic Bg va la kho vo tjn ve da vol. phuc vy cho nhiiu lmh vye Irong cong nghiep va dai sing hang ngiy nen dugc nhiiu nha dja chit nghien ciiu. Trai qua qua trinh nghien Cliu lau dai trong qua trinh lap cac to ban di dja chat 1/200.000 [2, 9] va cac to ban d i dja chil 1/50.000 [3-6] eung nhu cac eong irinh nghien ciiu ting hgp vc dja chat, dja ling, khoang san gin day [8, 10, 11], h? ling dugc nghien ciiu chi tiet hon va duge djnh tuii lai la Anisi. Vi m^l dja ting, cac cong trinh iren diu thgng nhat phan chia he ling thanh 2 phin (hay 2 tjp)
- Phan dudi gim da voi mau xam, phan lop lir rat mong din mong, khoang 500-600 m (?). trang binh 350 m.
^ - PhSn Iren la da voi phan lop day den d,ng khoi, mau xam, xam sam, vang ngi, xam irang, day tir vai tram din 1500 m.
Nhu \ ay. trong cac nghien eiiu vi dia
ehat, dja tang tii trude din nay khong nhac din nhirng lop dolomit trim tich trong phan dudi cua he ting, trir trong phan Ihuyel minh v i khoang san ciia cac 16 ban do co mo ta mgt vai diim dolomil nhirng cung chi noi chung chung la trong he tang IDong Giao ma khong neu Icn vj tri dja ting eu thi. Trong nhiing nam tir 2008 din 2010, cac lac gia ciia bai bao ed dip khao sal ky he ting Ding Giao qua mgt so hgp dong va di lai nghien ciiu va nhan thiy rang d phan thap nhai ciia he lang irong viing tir uiy bac Ihj trin Mudng Khin (Tan Lac, Hoa Binh) theo hirdng ddng nam keo xuong vimg Tam Di6p (Ninh Binh) co mgi lap dolomit kha day, phan b i i n djnh vh cd the khoanh dinh dugc tren cac ban d i ly le khac nhau. Dudi day xin md la mgt si mat cat dien hinh cua lap dolomil nay.
I. MAT CAT PHO RIA - PHO NGQC INHO QUAN, NINH BiNH)
Mat cil dugc khao sal dgc Iheo dudng 6 to 45 tit ihi Irin Rja (Nho Quan, Ninh Binh) di Th?ch Thdnh (Thanh Hda) (X = 20"l0' - 20''l5' B; Y
= I05"47- D) (Hinh 1). Kil hgp vdi m0t sd hanh trinh phu can ta Ihay mat cat cd trat lu nhu sau:
Hmh 1. Mgt cgt dig chdt Pho Ria - Pho Nggc
! ^ . ^ t : " f P ^ I ^ft.bOt.kSt vdi, hoacdua mdi 16 ro. Din len irin, lugng bgt ket chiia vdi va set voi man xam xanh
luc, phong hda miu vang nau, nau tun chiia hda thach ChSn diu va Hai manh vd:
Dienergcergs sp., SIbirites vielnamlcus.
Bakevellia exparrectg. Unignilesfassaensis I ... tudi Olenek cua hS ling Pa Khdm (Tio I pk) 14 dolomit, dolomit vol mSu xam den,
^ x4m sam, be mat bj khia vach nhan nheo dac tnmg. Da phan ldp mdng, nhiiu ehd bl phong hoa vyn nil. Quan sat thuc dia cho thSy cd nhtmg ngi dolomit tao thanh nhimg doi thap, nhung nhiiu noi dudi dang nhimg canh ding da sdt, gim nhimg ludng hojc nhtmg khii nhd cao Ht 0,3- 0,6 m den hon 1 m djnh hudng TB-DN.
Day chinh la noi canh tac cua dan va ehi vao djp diu nam khi dan thu hoach mia
voi tang din va chuyin thanh dolomit voi, voi dolomit. Bi day ciia nhihig ldp' dolomit, dolomit vdi d canh ding sdt thay doi Hi 5 din 10-30 m, d djng nhimg qua ddi thap len den gin 100 m (Hinh 2, 3).
yi mat cau true, ISp dolomit tao thinh nhan mgt nip Idm nhd cd true phuong TB -DN ma 2 canh la cac da luc nguySn - carbonat cua he ting Pa Khdm. 6 nhimg canh ddng da sdt, dolomit thuong cd gdc cam thoai (10-15°), eim v i phia tSy nam hoac dong bac, nhiiu cho gan nhu nim ngang va cd bieu hien uin lugn nhg. 6 nhung noi eg d?ng dgi thip hojc gin nhimg diit giy, dolomit cd gdc cim ldn hom va eung Ujeo quy luat chung la cim ve phia ddng bJc v4 lay nam.
Hinh 2. Cdnh dong gdm nhiing uing dolomil cila lgp Dolomit Pho Nggc a cira
vudn Qudc gia Cue Phuang
Hinh 3. Dolomit. dolomil vdi phdn ldp mdng cua lap Dolomit Phd Nggc a tdy
nam xdm Sdm. xd Ky Phd
^ g ; ] Set b0t chija v6i
Hinh 4. Mgt cat dia chdt Quang Son B. MAT CAT QUANG SON (TAY B A C TH| XA
TAM Q||P, NMH BINH)
Mat cat bat diu ttr ddng bic xa Quang Son, theo hudng tay nam cat qua trung lam xa va den khu vuc khai thac da ciia nha may xi mang Tam Diep (X = 20°9' 20°10' B; Y = 105°49- - lb5°5r D). Day cQng chinh_ la viing cd mat cat chuin cua h^ tang Ddng Giao. Trat tu dja ting tir dinii len nhu sau:
Nam Uyc tiip Uen cic da set bgt kit • voi. bgt kit vdi bj phong hda manhi mau xam vang, nSu phdi hdng ciia he ting Pa Kh6m(T|0pt)la:
1. Dolomit, dolomit vdi mau xam xam den, bj phong hda vun nat, thinh thoang con thay nhitag mdm hoac nhitag tang dolomit tan tieh, ehuyin din len Uen la nhitag Idp dolomit miu xam den, xam loang Id t?io nen nhitag qua dii thip. Day til viim din v4i chuc m.
^ Viing da set bgt ket chiia vgi cua hg lang Pa Khdm (T.o pk) va dolomit bj phong hda dudi dang canh dong da sdt cWnh 14 noi canh tac cua nong ttuong M n g Giao. T?i thdn Bai Sdi, c4c da cugi kel, bgt kel, s a bgt kit chiia phong phii di tich Chan bung cua h? ting Hang Mon (E, -Ni hm) phii khdng chinh hgp tren bi mjl phong hda ciia tap dolomit n4y.
2. _Da vdi chiia nhirng ddm vdi dolomit chuyen dan len da vdi phan Idp rit mdng - mdng, hat mjn den viia, mau xam slm, xam den, cd cho cd eiu tao phan d4i md va bj udn nep. Din len tren 14 da vdi phan ldp tmng binh. D4y khoing 300 m. Day chinh la da vdi thugc phin dudi h? tang Ddng Giao dugc mo ta Uong eic van li§u dia chit trudc dSy. Su chuySn tir dolomit ISn da vdi phin ldp mdng 14 rat tir tCr, do sir giam di ciia lugng dolomit v4 su tang len eua th4nh phin vdi.
Mat cat con tiip tjic kio dai ve phia tSy nam va chuyen len phin trSn eua hp ting Ding Giao gom da vdi m4u xdm, xam sang, trang nga, ed noi bj hoa hda.
v i vj tri dja ting, tlip dolomil d diy 14 lap Idt day cOa hp ting Ddng Giao. Vi ciu tnie, no 14 th4nh phan eiia cinh ddng bic cua nip lom cd tijic TB-DN theo trjlt tu eiu true tir ddng bic xudng lay nam 14: sfl bgt ket, bgt kit chiia vdi ciia hp ting Pa Khdm (T|0 pk) - dolomit, dolomit vdi - vdi dolomit - da vdi phin ldp mdng - d4 vdi phan ldp trung binh - d i voi phSn ldp day - djng khdi ciia he ting Ding Giao (Taa dg) vi nhm 14 cac ldp set voi, ed chi do 4nh hudng dilt gSy 14 d4 phien sfl vdi ciia he tang NSm Thim (Til nl).
w A ^ ; 5 ^ • * « 0 CAC M*T CAT KHAC VA VANBfTAPDOLOMrr
Ngo4i 2 mat cit chinh k i tren, chung toi cdn cd dip kh4o sat hoac quan sat thiy tip dolomit nay ed mat d nhiiu noi kh4c thugc phan ddng nam ciia cae d4i ttim tich carbonat he ting Dong Giao nhu: d vung Minh Tan (bic ddng bic thi ttin Nho Quan 6 km), vung nam xa Ba Sao (Kun Bang, H4 Nam) tten Quic Id 21 til Phu Ly di thi ttin Chi Ne (Lac Thiiy, Hda Binh). 0 2 viing nay, tap dolomit thudng la nhan ciia nhitag nip ldi nhd ma 2 c4nh la da vdi phan ldp mdng - ttung binh, da vdl phan ldp d4y - dang khdi cua phin duoi va phan tten hp ting Ddng Giao thudng dugc md ta.
Cl viing Huong Son (My Due, Ha Ngi), tren con dudng tii chua Thien Tni ien dgng Huong Tieh eiing cd thi quan sat
thay tap dolomit, dolomit vdi d 2 ben dudng. Do chiu anh hudng cua nhiiu diit gay ma diit gay chinh chay dgc sudi Yin nen nhiing ldp dolomit thugc phin dudi cua tap d day cd thi nim kha die, cd chd gan nhu die dung, len tren thoai din. Tuy vay, vin cd thi quan sat rd mdt ttat tu dja tang di len theo hudng ndi hdn. Tiiip nhit la nhung Idp dolomit, dolomit vdi d viing chua Thien Tni (Hmh 5), ga cap tteo dudi den chua Giai Oan (Hmh 6), day khoang 120 m. Tiep tten la nhung Idp vdi dolomit phan ldp mdng d vung din Ciia Vong, sau do la da vdi phin ldp trung bmh, mau xam sang, phan dai md d vung ga cap tteo tten va cudi cimg 14 da vdi phan Idp day - dang khdi d vach ddng Huong Tich. Trat tu dia tang tten (tag vdi phin day, phin dudi va chdm vao phin tten ciia h? ting Ddng Giao.
H i n h 5 . . . W . . . . ^ . ^ ^ ^^-^^onutv^dlhindmnghiing
Neu bai ky nh4 dja chil nao di tten Qude lg 6A, doan tii tay bic thj ttin Mudng Khen (Tan Lje) di thi ttin Mai CMu (Hda Binh) ttudc khi vugt deo cQng de d4ng quan sat thay mgt tap dolomit d vich ttai dudng d td va d ciih ding tan du gom nhimg mdm dolomit nhd cao ttSn be mjl nhirng thiia ragng d ben phai dudng. Tap dolomit d day eung cd vj tti dja lang va ciu tnic kha rd Nd la thanh
phan cua eanh ddng bic eua nip 16m cd trve TB-DN vdi ttat tu dia ting hrong tu nhu d vimg Quang Son (Tam Dipp, Ninh Binh), tir ddng bic xuing lay nam vdi thii tu: ttim tich luc nguySn carbonat he tang Pa Khdm (T,o pk) - dolomit, dolomit vdi - vdi dolomit, da vdi phan ldp mdng din vua - da vdi phan ldp day - dang kh6i he ting Ding Giao (Tia dg) va nhan 14 cac trim tich lye 33
"^
nguyen, luc nguyen-carbonat he tang Nam Thani (T2I "')•
Nhu vay, cac mat cat va cac vung vua ke tren cho thay tap dolomit co vi tri dia tSng ro rang: la tap lot day ciia he tang Dong Giao va duac chuyen tiep tu cac 16p luc nguyen-carbonat cua he tang Pa Khom len. Thanh ph4n ciia no la cac da dolomit, dolomit voi phan biet ro voi cac lop da duoi va tren no. Be day cua tap tiiy tung noi, thay doi lu vai met den
20-30 m d6n hang tram met vk hoan toan CO the khoanh dinh dugrc trfin cac ban do ty le khac nhau.
Vi dolomit la mdt khoang sin c6 J nghia thirc t8, dugrc sii dung nhi^u trong cong nghiSp nen theo Quy ph^m dja tSng [7], ngoai s6 thu tu, t§p con ducrc dat ten theo thanh phan dflc Irung kem ten dia Iy. Chung tdi dk nghi gpi la "t^p Dolomit Ph6 Ngoc"*.
P ' ^ J Ranh gidfi dy dodn
5km
NINH BiNH THANH HOA
^ ^ 5 k m 10km
^^^•^^^diinphdnbdeuatdpDolomliPhdNgQcdvmgNhoQuan-TamDiip
I^rf^l^S..'''"'''""''''""'''^
Qua tai lieu trinh bay d tten. he ting Ddng Giao ttong cac viing tir Hda Binh den Ninh Binh gdm 3 tap:
1/ Tap Dolomit Phd Nggc gdm dolomit, dolomit voi vdi bi day tir vai met den 20 - 30 m va din hang tram met;
2/ Tap da vdi phan ldp rii mdng - mdng, mau xam, day tii vai ttam din 500-600 m {?), tttmg binh khoang 350 m.
3/ Tap da vdi phan Idp day din dang khdi. mau xam, xam loang l i slm, ving nga, xam tring, day lir vai tram din 1500 m.
Theo khao sat ciia chiing tdi. lap Dolomit Phd Nggc phan bd dudi dang nhitag chudi diit doan cd hudng TB-DN trimg vdi hudng ciu iruc va phan b i ciia
• . h e lang. di kem chat che vdi cac trim tieh lyc nguyen-carbonat he linB Pa Khdm (T,o pk) nim dudi va da vdi phan ldp mdng Ihudc lap 2 cua he ling Dong Gino (Tia dg) nim tren. Chudi chlnh bat dau tir xa Phu Cudng (Tan Lac. Hda Bmh) a phia tay bac theo hudng ddng nam kSo xudng xom Nga a ddng nam vudn Qudc gia Ciic Phuong. lir day tao Ihinh mgt dii lien tyc dii hon 30 km, rgng hon 2 km qua Phi Ngoc (Pha Long, Nho Quan) cho din xa Quang Son (thj xa Tam Diep) vi cd thi keo dai den tan vimg mil Tri Tu thuoc phudng Ddng Son (ddng thj x i Bim Son) (Hinh 7). Iheo kel qui phan lich him lugng dolomil d dai niy khi cao. mlu phan lich o vung Nho Quan cho kil qua nhu sau (%): Cao = 30-31; MgO = 20 2- 21.4: FeO = 0.04-0.19; MNK = 43.57- 55 | 9 | . Ngoai ra, dolomil cdn phan b i rii rac cr nhieu noi khac nhu viing Minh Tan (bac ihj irin Nho Quan). nam Ba Sao (Kim Bing, Hi Nam), Huong Tich (M> Dure, Ha Ngi) nhu da ndi d tren ...
vi cd the cdn d nhiiu nai khic nhung chua phat hien ra.
d phan phia tay bic dipn phan bd ciia
he lang Dong Giao (cac tinh Son La.
Dien Bien, Lai Chau) chung tdi chua phat hicn dugc su cd mat ciia lap dolomit. Cac van lieu dja chit va thuc l i khio sit ciia chiing tdi cho thiy ring d viing nay. he ting Pa Khdm (T|op*) bit dau bang cac ldp lyc nguyen-carbonat, sau dd chuyen len nhirng ldp trSn chu yeu la carbonat chtra eac Chan diu, Hai manh vd Olenek mugn dac trung nhu:
Tlroliles cf. idriantis. Dinarlles (Plococeras) sp.. Anakashmirlles nivalis. Eumorpholis spinicosta .. vi ehuyen tiep ISn cic Idp da vdi phan ldp mong-trung binh thugc phin dudi cua he tang Dong Giao. khdng thiy cac Idp dolomil thugc phin diy cua he ling niy vi he tang Ddng Giao d cic vimg nay chi cd hai phan. Nhu vav d Tay Bic Bd vao cudi ky Olenek v i diu ky Anisi da xay ra sy phan dj ve diiu kien e i dia ly:
d phan lay bic, che do biin tin lai' liSn tyc dc lang dgng cic Irim tich tudng carbonat ihSm luc dja: d phin ddng nam.
bien thoii vi lag ra mdl s i biin, vjnh kin tao diiu kien eho viec thinh lao cae Idp dolomil. Diiu nay eung hoin loan phu hgp vdi ljch su phai triin dia chit Chung loin eiu la Irong giai doan giiia k.v Olenek v4 ky Anisi da xay ra nhifng bien ed dja chat 14m ca sd d i phan ehia 2 bae niy.
KETLUAN
Qua khio sat thuc dja d cae vimg lir Hda Binh din Ninh Binh, mdl ijp dolomit d Chan he lang Ddng Giao dugc phat hien va so bd danh gia. Tip nay duac dat ten li -lip Dolomit Phd Nggc". 6 nhitag vimg CO mat tap Dolomil Phi Nggc. he ling Ddng Giao gdm 3 lap. edn trong diSn tich cdn lai. he ling gim 2 lap.
Nhimg lai lieu mdi vi ihach dia ling nay cho Ihay li vio cuii kv Olenek, diu ky Anisi d Tay Bac Bg da xay ra nhflng Ihay doi ve dieu kien cd dja ly dS thanh tao nen lap Dolomil Phd Nggc vao Anisi sdm
35
cac lac gii bii bao xin Id ldng cam on TS. Tran Tan Vin va TS Ngu\en Thj -Minh Nguyei da tao diSu kien cho cie tic gia cd djp khao sat cac nam tt'ch he ting Ddng Giao d Tay Bac Bg. cam on TS.
Doin Nhat Tmdng da dgc ban thao v i gop >• cho bii bio.
% .i.N ULL 1. Ooijikoi A.E. (CAii bien), 197L Dja chat mien Bie Viet Nam (bin tieng Viet).
Nxb Khoa hgc vg Ky thudt. Hd Ndi. 1971.
2. Dinh Minh Mgng (Chd bien), 1978. Dja chit Id Ninh Binh. Thuyit mlnh bdn dd dia chdt td .\inh Binh ly le 1/200.000 Tdng cue DC. Hd Ngi
3. Do Van Chi (CAii biin), 1992. Bio cao Dja chat td Quan Hda - Vy Ban kem theo Bin dd dja chit ly IS 1/50.000. Luu trir Dia chdt. Hd Ngi
4. Le Thanh Huu (CAii biin), 2006 . Bio cao Dja chal vi khoang san nhdm to Yen Chau, kem theo Bin dd dia ehit ty le I /50.000. iira irt-r Djg chdi Hd Ngi
5. Ngu.\in Cong Lugng (CAii biin), 1978, Bao cao Dja chil vi khoang san
nhdm td Hda Binh - Suii Rut, kem theo Ban do dja chit ty le 1/50.000. Luu trir Dia chdt. Hd Ngi
6. Nguyin Dinh Hgp (CAii bila), 1994. Bio cao Dja chit v4 khoing san nhdm td Thuin Chau kem theo Ban do dja chil ty le 1/50.000. Luu tru dig chdt Hd Ngi
7. Tong Duy Thanh, \ ii Khue, Phan Cu- Tiin, 1994. Quy pham dia ting Vipt Nam. Cite Dja chdi. Hd Ngi
S. Tong Duy Thanh, Vu Khue {Ddng chu bien), 2005. Cac phan vi dja ling Viel Nam. .Vxh Dgi hgc Qudc gig Hd Ngi.
9. Tran Dang Tuyet (CAii Wen), 1978, Dja chat td DiSn Bien Phil. Thuyil minh kem theo bin dd dia chat ty" lc 1/200.000. Tdng cgc DC. Hd Ngi
10. Tran Van Trj (CAii bien), 2000, Tii nguyen khoing sin Vipl Nam. Cgc Dia chdt vd Khodng sdn Viet Nam. Hd Ngi
11. Tran Vin Trj, VQ Khiic (Ddng chti biin), 2009. Dia chit v i lii nguyen Vipt Nam. Cue DC&KS Viet Nam. Hd Ngi SUMMARY
On the dolomitK member In the bottom of Bdng Giao Fonnation, West Bic Bi), Vift Nam Nguyin Dinh Hiru. Dgg Thanh Huong we!" Bie B T I T ' ''K'i°",l'" 1 " ' " " " P ' " "^*= '^«"8 O'^"" F"™^""" (T^a dg) in
™ e d to b e l l H '"pJ'''t,''°'°"'''''^ ™™''" " * ^ l""'™ "f'W^ formation is toa d e m o n l r , ^ ' ' 7 ' ' ° ^F' °°'™''= ™"'''"" ^e^"^ "=" lithostratigraphic X g t r . D h k e o H V ™ ;•?' ' " ' " ' °'="'^'''^" '° '"= = " " " ' Anisian,'.he C T D ^ S r r r i h e - e t ' l i e X - s r ' ^ ^ ' ' ' '-'-'''' ' " '"^ ''^'''"^ "' '''
Ngudi biin tgp: VU Khtic
