Tm dli B U CHAT, loa A. s6 350. ^->,7015. tr. 3.1-41
DAC DIEM PHA HUY KIEN TAO VA VAN DONG TAN KIEN TAO VUNG CON DAO TRONG KAINOZOI
CHU VAN NGOI', NGUYEN HUtJ TUYEN-. PHAM THU HIEN'
' Trv&ng Dgi hoc Khoa hoc Tu nhien. 334 Nguyin Trai. Thanh Xuan Hd \m
- Vten Dia Vgt ly Ung dung. Vien HLKH&CNVN. 18 Hoang Quic Viet. Cdu Giiy. Hd Noi Tom tat: Viing Con Ddo bao gom 16 ddo lan nho. trong do Con San Id ddo lan nhat. Viing Con Ddo Id phdn ndi cao tren biin eda dai ndng Con San. mpt cau true dong vai ti-o la ranh giai giia bon triing Ciru Long vd Nam Cori San.
Viing CO edu tnie hai tdng: tdng mong cdu tgo chii yiu bdi cae dd magma xdm nhgp vd phun trdo cd thdnh phan tir mafic din aeid thupe edc phiic he Dinh Qudn. Deo Cd vd he tdng Deo Bdo Lpc. Nha Trang; ldng phu duac cau tao bdi cdc thdnh tgo trdm tich Pliocen - Be hi vai bi ddv khdng dang ki Do ed vi In kien tgo dgc biet. vimg Cdn Ddo dd trdi qua nhieu pha biin dang ldm eho cdc thanh tgo mong bi ddp vd vd phong hda mgnh Tren ca sd khdo sdt thuc dia nghien euu phdn tich edc quan he edu tgo theo khdng gian vd ihdi gian xti li- cdc sd lifu thu thdp aa xdc lgp duac 5 pha biin dgng phdn chia vimg Cdn Ddo tharih 5 khot hen triic. cdc dai dap vd vd ldm ro dgc diim chuyin dpng hin tao khoi tdng ciia vung.
I. Mt^OAU
Trfn them lyc dja Biln Ddng cd nhifu dio vdi quy mo khic nhau va ciu tao tir cac thinh tao dja chit khic nhau. Cic dio d vjnh Bic Bp chu yfu ciu tao tii cic di fram tich, d mifn Tmng vi Ddng Nam Bd til cic di xim nhip, phun frio vi d bifn Tiy cac dao ciu tao tii da magma vi trim tich. Cac dio xa bd nhu Hoang Sa vi Trudng Sa li cic dio san hd.
Cic dio d Bifn Ddng cd Ijch su phat trifn gin lifn vdi Ijch su hinh thinh vi phit trifn cic bdn trung d Bifn Ddng vi chju anh hudng cua tich gian Bifn Ddng.
Do do nghifn ciru die difm phi hiiy kifn tao frfn cic dio cd mpt y nghia khoa hpc frong viec xem xet ca chf hinh flianh cic bdn tiiing.
Vdi quan diem nhu viy, tap thg tic gii lya chpn vimg Cdn Dio fliudc ddi ning Cdn Scm mpt ddi kifn tao dupc hinh flianh trong Kainazoi lim ddi tupng nghifn cim phi hiiy kifn tao. Hon nua
vimg Cdn Dio di tiai qua nhifu pha bifn dang lifn quan vdi tach giin Bifn Ddng eiing nhu lich su phit trifn cic bdn trung trong Kainozoi die bift li hai bdn himg Cim Long va Nam Cdn Son.
II. DAC QI^M CAC T H A N H TAO BIA CHAT
Vimg Cdn Dio gdm 16 dio frong dd Cdn Son li dio Idn nhit, chiing phan bd frong pham vi ddi ning Cdn Son. Dai nang Cdn San frong Kauiozoi la ranh gidi giira hai bdn Cuu Long vi Nam Cdn Son [3, 5, 6] vi phan bd keo dii flieo phuang DB- TN, duac ciu tao chu yeu bdi da magma xam nhip cua phiic hf Djnh Quin, Deo Ca, di phun frao ciia hf ting deo Bio Ldc vi hf ting Nha Trang [2].
Hf ting Deo Bao Lpc chiem mdt difn tich nhd, phan bd d Niii Nhi Bin, cich trung tam thj hin Cdn Dio vi ddng bic khoing 3.000 m. Hf ting ciu tao bdi di phun fr^o andesit \ a mf vdi bf diy 100 m.
33
^mmm
»f Phirc he Dinh Quan phin bd d phan
ddng bic dio Cdn Son, chiem nua difn tich dio, gdm diorit horablen-biotit, diorit thach anh pyroxen homblen, granodiorit.
Nhm chung, di dap \d yfu, thudng bj phin cit ra cic khoi tang ldn (dpe bd bifn tai Bai Dim Triu).
Hf ting Nha Trang gdm di phun trio ryolit vi mf phin bd d tay nam dio Cdn Son vi mdt sd dio khic (Hdn Ba, Hdn Trie, Hdn Tai, Hdn Bai Canh, Hdn Cau, Hdn Tre...). Bf day cua hf ting 130 m, d i bj dip vd manh, tao ra cic ddi vd vun d Mui Ci Map. Trong hf ting Nha Trang ghi nhin nhifu ddi xiet trupt.
Phirc hf Deo Ci gdm cie da granit biotit bj dip vd, phan cit manh, phin bd chu yfu trfn dio Cdn Son. Ngoai ra, phiirc hf niy cdn phin bd vdi difn tich nhd d mpt sd dio (Hdn Trpc, Hdn Tre Nhd, Hdn Tning Ldn, Hdn Tning Nhd vi Hdn Bai C?nh).
Ngoii eie thinh t^o trudc Kamozoi, tai vimg Cdn Dio cdn cd cic thinh tao Pliocen - Df hi vdi be diy mdng, gom hf
ting Bifn Ddng phan bd d diy bifn, xung quanh dio ciu tao tir cit, bpt, set phan Idp nim ngang, frfn dao gap hf tang H|to Giang (Q2 hg) v i trim tich bifn (Q2").
He ting Hau Giang trfn dio Cdn Son chii yfu la cit phan bd d Tnmg tam Cdn Dio, d san bay Cd Ong. Ngoai ra, d mpt vai nai, chay ip sat ehan mii hf tang Hiu Giang tao nfn cac df cit cao 5-6 m. Tram tich bifn (Q2") phan bd d cic bai bifn d Vjnh Cdn San, Vjnh Ddng Bic va Bai Dim Triu (Hinh 1).
III. DAC D | £ M P H A HOY K|£N TAO Tai thyc dja, frfn co sd khio sit 17 difm dpe cic tayen dudng d Cdn Dio, da xic djnh dupc cic ciu t?o phi huy djc trung: tiirpt bing trai, trupt bing phii, xiet trupt trupt t h u ^ , xift trupt frupt nghjch, mit tich ldn, mat trupt thu|n, m$t trupt nghjch vi da xic dinh dupc tr?t ty phit trifn cua chiing theo thdi gian.
Cic phi huy die tnmg dupc xic djnh tai cic difm khao sit tifu bifu va vj fri cic diem khio sit dupc the hifn fren Hinh 1 v i md t i dudi day:
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Hinh I. Bdn do dia chdt Con Ddo [ 1 ].
34
CDI. Tpa dp: I0e33'38" - g'40'33-:
Difm khao sat nim sat mep nudc thudc bd tay bic dio Cdn Son, ciu tao tii da granit thudc phiic he Deo Ci. (3 day phit trifn cac he flidng khe mit, bao gdm: khe nih nguyfn smh (do ddng cumg tao thanh) vi cic khe nut kifn tao. Tai day tdn tai ciu tao thudc kifu frirpt bing ti^ keo dii flieo phuang 150° die frimg bdi cic khe nut cdng iing phit trifn vdi mat dp cao cd thf nim 240Z75'' vi 330Z70'' (Anh 1).
Anh 1. Anh chup tren mat nam ngang tgi CD the hifn tivpt bdng ti-di (Anh: Chu Van Ngai. 2014).
CD2. Tpa dp; I0lf35-19-- 8°38-55";
Di Ip d taluy ddc diing kfo dii flieo hudng 90°. Tahiy ciu tao tii di lyolit fliupc hf ting Nha Trang vdi mirc dp d ^ vd khic nhau. Difm khio sat la ddi dip vd manh rpng 4 m, chay flieo huiing DB- TN, phong hda miu ving. Hai bfn ria ddi dip vd di cdn tuoi, xim xanh khdng bi dip vd. Trong ddi dap vd - xiet tiirpt phiii xic djnh dip khe niit cpng img: 330Z50°
80Z55°(Anh2a).
O diu phia ddng tai ranh gidi dap vd quan sat mdt mat trupt thuan cd thf nim 210Z70 cit ddi dap \ d (Anh 2b).Trfn mat trupt cdn luru lai he khe niit cua ddi d|p vd. CJ diy thf hifn 2 pha bifn dang: pha sdm tao ddi dap vd - sin phim cua ddi xift tnrpt phai; pha sau tao mat trugt thuin cat ddi dap vd.
Anh li. D&i dgp va tgi taluy doc dimg (Anh: Olu Van Ngfri. 2014).
Anh 2b. Mat aval thugn cat d&i dgp va lAnh: Chu Viin Nggi. 2014).
CD3. Tpa dp; IOg'35 49' - 8^38 '42' ':
Difm khio sit nam d chin niii, eiu tao tir ryolit vi hif fliupc hf ting Nha Trang.
Ryolit miu xim xanh, ciu tao phin dai rd.
Trfn sudn Ip ra mdt ddi xift trupt trii flieo hudng DB-TN gdm di gdc bj phin cat bdi he khe nut thua vi cim ddc (cd thf nam 140Z70) vi cic khe nut cim flioii (30Z10) (Anh 3) fliinh cac khdi cd kich thudc Idn. Hai hf khe nut nay bj mat tiirpt diuan cd flif nim 290Z85 cit qua.
CD 4. Tpa dp: 10tf36 '20' - 8°38 '31'':
Difm khio sat nam d taluy duomg, doc diing, keo dai theo hudng 60° trfn dosm dii 100 ni, cau tao tur di phun trio ryolit fliupc hf ting Nha Trang, dupe chia fliinh 3 phan: phin tiy nam di xim xanh, tuoi;
phan giiia d|p vd, phong hda niu dd ipng khoing 50 m; phin ddng bic di xim xanh. Tai ranh gidi giiia phin tay nam vi phin giira flif hien rd mdt ddi xift tiirpt diuan theo phuong TB-DN, cd ciu tao ep phan tim manh. Mat xift fruot cd flif nim 220Z85 (Anh 4).
35
mm
Anh 3. Dd bfphdn cdt thanh khoi tdng l&n (Anh: Chu Vdn Ngai. 2014).
Anh 4. Cdu tgo d&i xiet truat Iheo ca che trugt thugn (Anh: Chu Van Ngai, 2014).
Anh 5. Dd bi dgp vtin gdy b&i trugt nghjch (Anh: Chu Vdn Nggi. 2014).
CD5. Tpa dp: 10<f36'43-'- 8'38'27":
Diem khio sit tai vich taluy duomg d Mui Ci Map. T^i diy quan sit thiy di ryolit hf ting Nha Trang bj dip vyn manh vi bj phong hda vdi mirc dp khic nhau. Khoi di bj cit ra thinh cac tim day, trupt hrong doi vdi nhau theo co ehe hirpt nghjch. Mit tiirpt cd the nim 240ZI9 vi cic phien 240Z45 (Anh 5).
Diy li sin phim ciia nfn fp.
CD6 Tpa dp; 10ff'36'46"-8°38'27':
diem khio sit d diu Mui Ci M|ip, tai do^n uon cong, taluy duong cd ciu t?io d§c trung: phin thip bj phong hda cd miu niu ving, phan ti^n di rin chic.
Anh 6. Dd bj dgp vi/n gdy b&i trugt thugn (Anh: Phgm Thu Hien, 2014).
miu xanh (hf ting Nha Trang K nt). Ve ciu t^io tai day thf hifn rd mpt ddi xiit trupt thu^n. Trong ddi xiet, di bj d|p vyn, fp tim. Mat phi hiiy cd thi nim
l90Z40(Anh6).
CD 7. Tpa dp; 106"37'43"-8°41 "55";
Difm khio sit t^i Doc Triu Tf. Di c6 miu xim, kifn hiic hat thupc phirc h?
Djnh Quin. Tai day die trung bdi mpt ddi xift tiirpt m?mh me. Ddi xift trupt c6 phuang 40°, ed diu hifu tiirpt phii, thf nim ciia ddi xift 140Z83. Ngoii ra cdn cd mit hirpt nghjch vdi thi nim 160Z53 cit ddi xift tiirpt (Anh 7a, b).
Anh 7. OCT »ef tivgt (a) vd mgt tiuat nghieh cat ddi xiet tivat (b) (Anh: Chu Van Ngai, 2014).
CD II.
8°4r38":
Tpa dp; IOS'39'19' Til mui Chim Chim nhin vf ddng nam li Hdn Bai Canh vdi bd bic ddc chay theo hudng ddng-tay. Tai bd niy quan sit cd
^ic^dudng mit doc diing, rpng chay flieo j . i kinh myen. Tuong ty quan sit _|f thdng dudn^ nut cd phuang i
myen tai bd bic cua mui Ta Bf (Anh 8) vi tai bd bic cua Hdn Trie cic dudng nut vdi chieu rpng hi 1 met den vii met [1]. Ngoii ra flieo tii lifu inh vf tmh, t^i bd bic Hdn Cau cung cd nhung dudng niit theo hudng bic nam. Cac dudng nut
Anh 9a. Trugt phdi chong ten trugt tidi (Anh: Chu Van Nggi. 2014).
CDI 2. Tpa dp; lOff'39'25"
8'4r4: •
Difm khao sit nim tai yfn ngya miii Ti Bf. T^ diy hai bfn dudng taluy duong cao, ddc diing bj dap manh, phong hda miu ving nau. 6 bfn taluy phii (tinh hi sin bay Cd 6ng di ve Trung tim Cdn
li sin phim cua trudng lyc cang ngang theo hudng i vT myen.
Anh 8. Du&ng nirt v&i vdch dOng ehgy theo hu&ng bdc nam Ufi MUi Td Be (Anh Chu Van Nggi. 2014).
Anh 9b. Cau tgo trugt thugn (Anh: Chu Vdn Nggi, 2014).
Dio) gjii nhin chuyfn dpng trupt frai flieo phuang 170° bj chuyfn dpng frupt phii cung phuomg ve sau phit hifn chdng Ifn.
p i f nim ddi xift tiirpt 80Z85 (Anh 9a).
0 day flif hifn rd 2 pha trupt bing rd rft.
Ngoai ra cdn quan sat dupc cau tao tiirpt tiiuan (3I0Z45 vi 135Z75). Tai diy fliiy
37
£i.'^
mm
rd mat tmpt thuan phit trifn theo mat he khe nirt 310Z45 vi lam cho he khe nut
135Z75 bj udn cong (Anh 9b).
CDI 3. Tpa dp; 10^ 3923'' 8"41'46"; Difm khao sit nim bfn frii dirdng tii mfli Ta Bf di sin bay Cd Ong.
Taluy thap vdi die difm: diu tay bac taluy ddc, cau tao tii di magma thudc phiic hf Deo Ca, phat trifn cac khe mit nguyfn sinh. Trfn dinh taluy luu giii ldp cupi, ting; Dau ddng nam taluy thoai, da bi dip vun, phia frfn taluy li Idp cudi, ting diy frfn 1 m Id d ehan sudn thoai.
Ldp cupi, ting phan bd d dp cao tir 100 m li chimg cii dudng bd co. Difm khio sit nam tai ranh gidi giu:a ddi dap vyn (a) vi ddi khdng bj phi hiiy (b) thf hifn li mpt diit gay fliuan (310Z65) vdi die diem cinh ddng nam da bj nfn vi udn cong, cdn d cinh tiy bic di it bi phi hiiy (Anh 10).
Anh 10. D&i dgp vyn la) vd d&i khdng bjphd buy (h) bj phil b&i l&p cugi tdng
(Anh Chu Vdn Nggi. 2014).
ifmw.u" • T
CD16. Tpa dp: 106°39'H"
8°42'20": Difm khio sit d bfn phai dudng (di tit san bay Cd Ong vf Tnmg tam Cdn Dao). Di goc Id d taluy doc dimg keo dai 150 m flieo hudng 300°, bj phan cat manh. He thdng khe nurt chinh c6 the nim 300Z75, he lifn quan ed flif nim 160Z70. Tai difm khao sat dif hifn ddi nen ep theo ca che xift trupt nghjch (Anh 11).
106°27'17"
CDI7.
8°43'55"
Tpa dd:
Diem khao sit nam d bd tay nam Bai Dam Trau. Bd bifn dang vich ciu tgo tit d i magma thupc phiic hf Djnh Quan. Cac khe mit kien tao thua, kem phat trifn, da phan cat da ra cic khdi ldn. Cac khdi tang ldn xip chong Ifn nhau d ehan vich (Anh 12). Nhin chung, tai difm khio sat bieu hifn phi hiiy kiln tao yfu.
Nhgn xet; Qua kit qua khio sit thiy ro die diem phi huy kiln tao frfn dio Con San nhu sau:
- Phan tay bic dio bilu hifn phi huy yfu, thf hifn: cic khe mit thua vi di bj phan cit thinh cic khoi tang ldn, khdng cd bifu hifn dap vyn.
Anh 11. Cau tgo trugt nghjch tgi vdch doc (Anh: Nguyen HQu Tuyen. 2013).
38
Anh 12. Vach doc yd cdc khoi tdng l&n do l& (Anh: Nguyen Hieu Tuyen. 2013).
_- «imii uuug uaiii Knoi nang trung lam bifu bifn phi hiiy manh, cac da bi d ^ vd theo hudng DB-TN tao thinh cic ddi x i ^ trupt dan xen vdi cac ddi khmig bi dap vd.
- Cac ddi dap vd theo hudng TB-DN kem phat trifn ban so vdi hudng DB-TN
Cic fliinh tao di magma thudc he ting Nha Trang, phuc he Deo Ci bifu hifn bi pha buy manh hon so vdi d i thudc phirc he Dinh Quin.
Trang thai ung suit vi tinh chit phi hiiy kifn tao dupc thf hifn d Bing 1.
Baig 1. Tryig thai iing suat va tinh chat pha huy kien tjK>
Diem k U o sat CDI CD 2 C D 3 CD 4 CDS
0'
C D 7 C D I I CD 12 C D U CD 16
cac kbe nvt 240Z75 300Z70
330Z50 80Z55 I40Z70 30Z10
240Z75 140Z83
80Z8S 140Z83
Mattnrgrt dot gay
210Z70
290Z85 220Z85 240Z20 I90Z40
160Z53 360Z90
310Z45 310Z65 300Z7S
Trang tkal n g suit al
90Z20 30Z65 120Z30 170Z50 110Z50 40Z50 60Z25 190Z85 lOOZlO 160Z10 a|Z90 200Z5 a i Z 9 0 130Z70 300Z30
CT2
290Z70 120Z0 360Z50 55Z20 20Z0 130Z70 150Z0 lOOZO 200Z70 70Z0 180Z0 110Z85 220Z0 220Z0 30Z0
o 3 180Z10 210Z35 210Z40 260Z70 290Z40 220Z40 240Z65 10Z5 10Z20 70Z80 270Z0 290ZI0 310Z0 310Z20 120Z60
Bac (Hem pha hny Cap khe nut cong ling
Mat tnrat thuan Cf]) cpng ling Cap cpng ung Mat tiupt tfaului Doi xi£t thuan Doi xiet nghieh Doi xiet thu|n Cap cpng ung Mat tnipl nghieh Niit lach Cpng ung Dlii xiet thuan Diit gay thuin Doi xih nghjch
Pha bien dang 1 2 1 4 5 2 3 2 1 3 5 4 5 5 3 IV. VAN OQHG K | £ N TAO V O N G C G N
DAO
Cic pha bifn dang, cac hf thong phi huy kifn t?o tifn dio Cdn Son, die difm hinh thii dia hinh \iing Cdn Dio (ciu tao phin b|c, hudng dia hmh, dp cao, bf mat dinh va sudn dja hinh, cic ranh sau diy bifn keo dii) vi cic dudng bd cd phin nio phan anh die difm van dpng kifn tao vdng Cdn Dio trong Kainozoi.
1. Cic pha bien d^ng
Dai nang Cdn Son bi khdng chl bdi hai he fliong diit gay cd phuang TB-DN vi DB-TN vi trai qua nhifu pha bifn dang lien quan chji che vdi qua trinh hinh fliinh %i phat trien cic bdn triing frong Kainozoi. Viing Cdn Dio nim trfn ddi
ning Cdn Son, li khdi ning frong Kainozoi, ehiu inh hudng true tifp bdi cic pha bifn dang Tin kifn t?o. Cic pha bifn dang xic lip trfn viing Cdn Dao phin inh mdt phin die difm biln dang ciia ddi nang Cdn San frong Kainozoi.
Ket qui khio sat, phan ti'ch cic ciu tao vi xu ly so hfu fliu fliip da xic lip 5 pha bifn dang (Bang 1).
Pha I: Day li pha die himg bdi chuyfn ddng theo co chl truat bing trii ddi vdi cac dirt gay phuang TB-DN vi trupt bing phii ddi vdi cic diit gay phuang DB-TN, tao ra cac ddi dap vyn, xiit trupt hudng TB-DN vi DB-TN, phi buy mdng trudc KZ vdi hudng nen ep ddng tay \ a i vi myfn vdi gdc nghifng 39
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ify0!
flioii: CT,: 90Z20 tai CDI. a l : 120Z30 tai CD2 vi CT|: lOOZlO tai CD7.
- Pha 2: Pha 2 li pha cing gian vdi tryc 03 chii ylu cd phuang DB-TN: a3:
210Z0 tai CD2, 03: 220Z0 tai CD 4 vi 03: 10Z5 tai CD 6. Lifn quan vdi pha niy di hinh thinh cic durt gay thuan hudng TB - DN, chia viing Cdn Dio ra cic khdi kifn tnic.
- Pha 3; Die trung cua pha 3 li nen ep vdi tryc oj theo hudng TB-DN vdi gdc nghifng thoii: Op 160Z10 tai CD7 vi oi: 300Z30 tai CD 16. Kft qui pha niy da tao ra cac diit gay nghieh, cic ddi xift nghjch lim cho di bj vd vun manh.
- Pha 4: D|c himg bdi frupt bing ddi chifu vdi O] cd phuang i kinh myln (oi: I70Z50 t^i CD3 vi CTI: 200Z5 tai CD 12. Hoat dpng cua pha niy t^o ra ddi dip vd mdi vdi die difm cie di khdng bj bam vyn...
Pha 5; Cd till diy la pha fre nhit trong vimg Cdn Dio, hirdng lyc cang nim ngang, hudng ddng tiy vi tay bic ddng nam (ay. TliiZ.Q tai CDI 1, oj: 310Z0 tai CDI2 vi 03: 3I0Z20 tai CDI3) li nguyfn nhin giy ra cic dudng nirt Idn [6]. Cd If lifn quan vdi pha niy di xiy ra cie boat dpng magma phun trio bazan Pliocen Df hi d cic ddi ning (dio Phu Quy, dio Ly San vi dio Con Cd).
2. Cic hf thdng phi huy ki6n t^o Cac hf flidng phi buy kifn t(io d vimg Cdn Dio die ttimg bdi cic diit giy vi cac ddi xiet tiirpt (Hinh 2).
a) Cic dirt gay:
Cic diit gay hudng TB-DN khi phit trifn, chiing ddng vaj trd phin chia viing Cdn Dio ra cie khoi kifn true.
Trfn Nui Thinh Gii dirt gay Diu Ddc - Mui Ci Mip thf hifn li ddi phi buy
I
vdi die difm hinh dpng hpc phiic tjp:
Trong pha 1 diit gay chuyfn dpng theo CO chf trupt frii, pha 2 theo co chl thuan, pha 3 theo ca chf nghjch, pha 4 theo ca chf trupt bang phii.
Cac diit gay phuang TB-DN khic dupc xac dinh frfn ca sd phan tich die difm sudn va dja hinh diy bien: Diit gay Bfn Dam chay theo lach sau hudng TB- DN ngan each khdi Niii Thinh Gii vdi khdi Nlii Hdn Ba... Diit gay Ddng Bic niii Thinh Gii dupc thf hifn dudi dang vich ddc kfo dai theo phuang TB-DN. Diit gay Bai Dim Triu Mui Ti Bf flif hifn ro dudi dang vach ddc keo dai theo phuang TB-DN.
- Diit gay hudng DB-TN
-I- Dut gay tay bic dio Cdn San dupc xic djnh dya frfn die difm dia hinh diy bifn: dja hinh diy bifn chay sit bd djc trung bdi mpt lach sau vdi chieu rpng gin
1000 m, keo dii flieo phuang DB-TN ngin cich cic dio Hdn Tre Ldn vi Hon Tre Nhd vdi dio Cdn Son. Dja hinh diy siu h^ bic la kit qui ciia ho^t d^ng dut gay vi xam thyc.
+ Diit gay Mui Ta Bf - Mui Ci Mip kfo dii theo phuang DB-TN, thf hifn li ranh sau cimg hudng, ngan cich dio H6n Bi vi Dio Cdn San vdi cac Hdn Bay Canh vi Hdn Trie.
+ Diit gay ddng nam Hdn Biy Canh keo dii dieo l?ch siu hudng DB-TN, till hifn i\f h? dp siu diy bifn rd rft hi 16-18 m xu6ng 27-53 m.
- Cic dudng nirt hudng bic nam. Cic dudng mit ldn hudng bic nam bit gip 0 mpt vii vj tii: bic Hdn Trie, bic Mui Ti Bf, bac Hdn Biy C?nh vi bic Hdn Cau (flieo inh vf tinh). Diy li phi huy kiln tao tre vi li nft die frung ciia viing Cdn Dio.
f
^ 1 a i . , ^ mm ttrngCvlmt• • rrti r^, w T.a^ Lfc
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^ H 3 -
Hinh 2. Sadd cdu true
b) Cac dai xiet tnrgrt:
Trfn dio Cdn Son da xic dinh dupc mpt sd ddi xift ttupt theo ca chl tnrpt bing, frupt nghjch vi trupt thuan. Cic ddi xift trupt phuong DB-TN tap ttung d phin ddng nam dao Cdn Son (ddi xift trupt Hdn Bi - Niii Ong Cudng, ddi xift trupt Miii Ci Mip) phat triln nhifu ban so vdi cac ddi xift tnrpt hudng TB-DN (ddi xift trupt Hdn Trpc - Mui Ci Map).
Trong cac ddi xiet trupt di bj dip vd vi bim vyn.
3. V?ln dpng kien t^o trong Kainozoi Trfn ca sd khio sit, xir ly sd lieu vi tdng hpp cac tii lifu thiy rd viing Cdn Dio li viing ning trong Tin kifn tao vi vin dpng ning cd die tinh khoi tang.
- Van dpng nang ha trong Tin kiln tao:
kien tgo vimg Con Dao.
Vao thdi ky tifn rift (trudc Eocen) toin bp viing thfm lyc dia hifn nay li vung lyc dia hi san bing bdc mdn. Vio Eocen mudn - OUgocen sdm bit diu mdt thdi ky mdi - Thdi ky hinh thinh cac bf tram tich Kainozoi, trong dd cd bl Cuu Long vi Nam Cdn Son. Tir day hai bf dupc ngan cich nhau bing ddi nang Cdn Son. Vio cudi Oligocen mudn xiy ra pha nen ep lam cho toan viing nang cao va bio mdn vi kit fliiic thdi ky ddng rift.
Thdi ky sau rift bit diu tu Miocen sdm. Vao thdi ky niy qui trinh gian diy Bifn Ddng flieo phuong TB-DN da ylu va kit thiic vao cudi Miocen sdm vi tifp flieo la qua trinh ngupi lanh vd kem flieo syt liin trfn difn rpng df tao nfn ting "set Rotalid" Vio cudi Miocen sdm toan bf trii qua qua frinh nang khu vuc \a bdc mdn veu.
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-8^ l + j Nhu viy, tir Eocen dfn cudi Miocen
sdm vung Cdn Dio da frai qua cac pha nang lifn quan vdi qua trinh tao bf va van ddng nfn fp ning cao khu vuc da tao ra cac bf mat bit chinh hpp.
Tir Miocen mudn, hai bf Cihi Long vi Nam Cdn Son di lifn thdng. Sang Pliocen Be hi, bifn tifn trfn pham vi rdng Idn lifn quan vdi syt lun nhift khu vuc dan den toin bd thfm lyc dja nim dudi bifn.
Viing Cdn Dio bj ldi cudn vio qui trinh sut lim nhift khu vuc. ngoii phin ndi cao, t^i phin ria da xiy ra ling dpng ting tram tich Pliocen - Df tir, hinh thinh mpt ting fram tich vdi ciu tao phan Idp nam ngang vi bf diy ting ve phia cic bon trflng.
Tai vung Cdn Dio ghi nhin hai dudng bd cd: Mpt ducmg nim d dp eao 100 m (Anh 10) vi mpt dirdng bd cd thf hifn li cic de eit cao 5-6 m ch^y men theo chin nui do bien tifn Flandrian tao nfn (Anh 13).
.•\nh 1 .V lie cat -tidu lich du&ng ha i n luen licn Flandrian (Anh: Phgm Thu Hien. 2014).
Diu tich cic dudng bd cd thf hifn rd quan hf giira vin dpng ning kiln tao vi sy thay ddi myc nudc bifn.
Vin dpng ning kiln tao frong Kainozoi d vimg Cdn Dio thi hifn sy khic bift giua hai flidi ky: thdi ky tii Eocen - Oligocen dfn cudi Miocen sdm die frung bdi vin dpng ning dn djnh;
Thdi ky tii Miocen mupn dfn Pliocen Df hi die frung bdi vin dpng nang yfu vi bj Idi cudn vio syt lun nhift khu vye.
- Vin ddng kien tao cd tinh khdi ting:
vung Cdn Dio the hifn vin dpng kiln t^o trong Kainozoi cd ti'nh khdi ting. Difu do dupe thf hifn qua hinh thii dja hinh, die difm sudn va cic bf mat dinh cd dp cao khac nhau.
Trong ph^m vi viing Cdn Dio cd thf ehia ra cac khdi kien true ning: khdi Hon Ba, khoi Trung tam, khdi Niii Ong Cudng, khoi Hdn Tre Ldn vi Hdn Tre Nhd, khdi Hdn Bay Canh vi ria syt liin frong Pliocen - De hi. Ranh gidi giira cac khdi la cic diit gay (Hinh 2).
Cic khdi nang cd die trung sudn d6c, bf mat dinh rdng vi nghifng thoii (phin ndi cao frfn myc nudc bifn), phan ngip nudc dja hinh bang phing vi cau t^o syt bic rd. Trong cic khdi kiln tiiic, khfi Trung tam li khoi nang manh ban ci, mit dinh dat dp cao tir 400 m din 500 m, cac khdi cdn lai thupc difn nang ylu (mjt dinh dat tii 100 m din 300 m).
Ria syt lim cd dja hinh bing phing hoie nghifng thoii.
V. KtT LUAN
Vimg Cdn Dao cd ciu hiic dja chat dan giin. Tang mdng ciu tao tit cic da magma Mesozoi thudc hf ting Dfo Bao Lpc (J3 dbl), phiic hf Djnh Quin (5-v6J3 dq,), hf ting Nha Trang (K nt), phiic hf Deo Ci (y K da). Ting phu cau tao tii cic thanh tao Pliocen Df hi vdi bf diy mdng.
Cdn Dio thupc khdi nang Cdn Som, c6 cau tnic khdi tang rd ret, vdi die dilm vin dpng tan kiln tao phin dj, da t?o nfn 5 khdi nang trong Kainozoi vi ria syt liin frong Pliocen - Df hi.
Die diem phi buy kiln tao thi hifn sy phan dj rd rft: tai Mfli C i Map vi Mui Ti Bf cic thanh tao dja chit bj dap vd vdi myc dp cao, frii qua cic pha nen ep va cing gian. Phin tay bic cua dio, cic thinh tao dja chit bj dap vd ylu.
Iren Cdn Dao gjii nhin 5 pha bifn dang. Kft qua hoat ddng kiln tao da tao nen cic ddi phi buy, dip vd theo phuang TB-DN vi DB-TN. Pha 5 la pha frf nhit vdi CT3 hudng D-T hoac i vi myen da tao ra cic dudng niit chay theo phuang bic nam vdi chifu rdng ldn, cd chd vai mft.
Lcri cam cm: Bii bio nhin dupc sy ho frp cua Df tai KC.09.20/11-15, Ban chii nhifm chuang frinh Biln KC.09/11-15 vi Trudng Dai hpc Khoa hpc Tu nhifn, DHQGHN. Tip thf tic gii xin tran frpng cam an.
VAN LIEU
1. Le Trieu Vift, 2013. Die difm dap vd kifn tao, boat dpng dirt gay vi trang thai dia dpng luc vung quin dio Cdn Dao.
7"C£>/a chdt, A;336-337;61-69. Hd Npi.
2. Nguyen Ngoc Hoa (ChU bien), 1994. Td Tri Vinh Cdn Dio, ty If 1:200.000. Cue Dia chdt vd Khodng sdn Viet Nam.
3. Jacques Angelier and others, 1990. Paleosttess analysis as a key to margin extension: The penghu Islands, South China Sea. Elsevier Science Publishers B. V.. Amsterdam; 161-176.
4. Tap doan Dau khi Viet Nam, 2007. Dja chit vi Tai nguyfn diu khi Vift Nam. Nxb Khoa hpc vd Ky thudt, tr 549. HdNpi.
5. Tran Van Tri va Ding Vfi Khiic (BSng Chu bien), 2009. Dia chit va Tii nguyfn Vift Nam. Nxb Khoa hpe Tu nhien vd Cong nghe. tr 598. Hd Npi
SUMMARY
Characteristics of tectonic fractures and neotectonic movement of Con Dao region in Cenozoic
Chu Vdn Ngfri. Nguyin HOu Tuyen. Phgm Ihu Hien Cdn Dio region are composed of 16 different sized islands, of which Cdn Son is the largest one. Cdn Dao region is a part of flie Cdn Son uplift zone and plays a role as the boundary between Cuu Long and Nam Cdn Son basins. Cdn Dio region has two-tier stiiicmre: basement part consists mainly of infrusive rocks fi-om mafic to felsic components belonging to flie Djnh Quin and Deo Ci complexes, as well as Deo Bio Lpc and Nha Trang Formations. The upper part consists of Pliocene Quaternary sediments with negligible fliickness. Due to flie special tectonic position, lower Cdn Dao region has undergone several defonnation phases wifli sfrong cmshing and weathering process. Based on field researches and sfruemral analysis in space and time, integrating and processing collected data, the article has touched upon characteristics of tectonic fracmre; sfress state and tectonic movement of Cdn Dao region in Cenozoic. The results reveal 5 phases of tectonic deformation which divided Cdn Dio region into 5 shiiemral blocks and tectonic movements.
Nguai bien tap; TS Le Trieu Viet.
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