N o 2 S e rie s B yxwvutsrqponmlkjihgfedcbaZYXWVU 2003 DEPARTMENT & MINERALS OF VI~T NAM OF GEOLOGY cbaZYXWVUTSRQPONMLKJIHGFEDCBA H A NQI T~p ZYXWVUTSRQPONMLKJIHGFEDCBA c h i B fA C H A T Cl)C DfA CHAT cbaZYXWVUTSRQPONMLKJIHGFEDCBA & KHOANG SAN Loat B, VI~TNAM sa TSRQPONMLKJIHGFEDCBA 2 /2 0 MUCLUC • e, Trang Tdn Van Trj, Tdn Du'c Th~nh, Tony Waltham, Le Duc An, L~i Huy Anh Di san th€ gioi vinh H(;1Long: Nhfrng gia tri n6i bat v~ dia ch~t Nguy~n Hfru Hung Tr~m tich Devon thuong, S\I tuyet chung hang 10(;1tcua hoa thach Ian va ranh gioi Frasni/ FamenutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (y B~c Viet Nam 19 DB Bat, Nguy~n QuBc An, Nguy~n Quy Hung, Ngo Xuan Vinh, Nguy~n Th~ Hung, DB Vi~t Hi~u, Nguyen Trung Hi~u Dia tang tram tich D~ tam them luc dia Tay am Vi~t Nam 31 Tdn Ngnc SHRIMP sinh am, Y Sano, S L Chung Chung cir moi 2840 trieu nam tir U-Pb zircon cho tu6i Archei cua plurc h~ Ca Vinh va y nghia nhiet ki€n Nguy~n Kim Lap, 41 DB Chi~n Th~ng, Bui Vi~t Dung Dac diem dirt T:ai ~~t tren I~nh ~h6 yi~t,Na~ bao,( gom quan dao Truong xac dinh co che chan tieu cua dong dat g a y (y Sa dira tren k€t qua 49 Ngo Th] Lu Cac tran dong d~t manh va dac di~m hoat dong ki€n t(;10(y khu Dong Nam A Tr~n Trong Hu~, Ki~u Quy Nam Khoang hoa sericit (y Viet Nam va kinh t€ cua cluing Phan Th] Kim Van vo y V\IC 54 nghia 61 Xu Iy cac s6 lieu tir phuc vu tham d~u 70 Journal of GEOLOGY EDITORIAL OFFICE 2 / 0 utsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Series B, NoTSRQPONMLKJIHGFEDCBA 6, Pham Ngu Lao, Hi! NQi (F ourty th ird year) 6, Nguyen Hong, B6ng Ba, Hi! NQi Tel: (048) 261 779,352319,355468 Fax 84 254 734 Email: tapchidc@hn.vnn.vn EDITORIAL BOARD Editor-in-chief: NGUYEN THANH V AN Deputy Editor-in-chief: TRINH DANH, TRINH XUAN BEN Secretary: BUI ouc THANG Members: DUONG cue KIEM, BAa BiNH THVC, D1NH THANH, NGUYEN ouc BAI, NGUYEN KHAc VINH, NGUYEN HU'U TY, NGUYEN TIEN BAa, NGUYEN XUAN BAa, vO, PHAN TRUONG TH!, TONG DUY THANH, TRAN MINH, PHAM NANG TRAN MINH THE, TRAN TAT THANG, TRAN V AN TR!, vO KHUC CONTENTS Page TrAn Van Trj, TrAn Due Th~;mh, Tony Waltham, Le Duc An, L~i Huy Anh The Ha Long Bay World Heritage: Outstanding geological values Nguy~n Hiru Hung Upper Devonian sediments, mass extinction of macrofossils and Frasnian/Famennian boundary in North Viet Nam 19 DB Bat, Nguyen Quac An, Nguyen Quy Hung, Ngo Xuan Vinh, Nguy~n Th~ Hung, DB Vi~t Hi~u, Nguy~n Trung Hi~u Stratigraphy of Tertiary sediments in the Southwest Viet Nam continental shelf 31 TrAn Ngoc Nam, Y Sano, S L Chung New evidences of 2840 Ma from SHRIMP U-Pb zircon dating for Archean age of the Ca Vinh Complex and tectonothermal implication 41 Nguyen Kim Lap, DB Chi~n Th~ng, Bui Vi~t Dung Characteristics of the faults in the Earth's crust of the territory of Viet Nam including the Tnrong Sa Archipelago based on the results of determination of focal mechanism of earthquakes 49 L u , Strong earthquakes and features of tectonic activities in Southeast Asia Ngo ThjcbaZYXWVUTSRQPONMLKJIHGFEDCBA region 54 Tr§n Trong Hue, Ki~u Quy Nam Sericite mineralization economic significance Phan Thi Kim Van Magnetic exploration data processing in Viet Nam and its 61 for the purpose of hydrocarbon 70 Journal of GEOLOGY Series B N".2212003 p.I-18ZYXWVUTSRQ THE ~ L O N G B A Y W O R L D H E R IT A G E : O U T S T A N D IN G G E O L O G IC A L VALUES TRAN V AN TRI1• TRAN cbaZYXWVUTSRQPONMLKJIHGFEDCBA o u c THANH2, TONY WAL THAM 3, LE ouc AN4, LAI HUY ANH4utsrqponmlkjihgfedcbaZYXWVUTSRQPON 'National Committeefor ICCP of Viet Nam 'Instuuie of Oceanography, 246 Da N{mg, Hili Phong 'Nouingham Trent University, NGI, 4BU, United Kingdom "Institute of Geography, 18 Hoang Quoc Vi?t, cdu Gidy,TSRQPONMLKJIHGFEDCB H a N6i A b s t r a c t : In 2000, the UNESCO's World Heritage Committee has inscribed the H a Long Bay in the World Heritage List according to its outstanding examples representing major stages of the Earth's history and its original limestone karstic geomorphologic features The H a Long Bay and its a d j a c e n t areas consist of a part of the Sino- Vietnamese composite terrane having its development history from preCambrian up to present day During Phanerozoic, terrigenous, volcanogenic and cherty-carbonate sediments containing in abundance graptolites, brachiopods, fishes, corals, foraminiferas, radiolarias, bivalves and flora, separated one from another by 10 stratigraphic gaps, but the boundary between Devonian and Carboniferous has been considered as continuous The limestone karstic geomorphology of the bay was developed since Miocene, especially the cone-shaped hills ( f e n g c o n g ) , or isolated high limestone karst towers (fenglin) with many remnants of old phreatic caves, old karstic foot caves, marine notch caves form magnificent limestone karst landforms as unique on the world The Quaternary geology was developed through cycles with the intercalation of marine and continental environments The present H a Long Bay, infact, appeared after the Middle Holocene maximum transgression, leaving ultimate zone of lateral undercutting in the limestone cliffs bearing many shells of oysters, having the J.JCage as 2280 to >40,000 y BP Geological resources are abundant: anthracite, lignite, oil shale, petroleum, phosphate, limestone and cement additives, kaolin, silica sand, dolomite, quartzite of exogenous origin, and antimony, mercury of hydrothermal origin Besides, there still are surface water, groundwater and thermal mineral water on the shore of the H a Long - Bai T u ' Long Bays and other environmental resources.ZYXWVUTSRQPONMLKJIHGFEDCBA IN T R O D U C T IO N The Ha Long Bay is situated in Northeast Viet Nam, belonging to the Quang Ninh Province, adjoining to Hai Phong City, with an area of 1553 krrr', including 1969 islets It has been incrisbed as sights of national category by the Ministry of Culture and Information in 1962, and as World Heritage in 1994 according to the 3rd criterion of the World Heritage Convention by having outstanding natural landscape of high aesthetic value This bay is limited by the f)~u G6 Islet in the west, the Ba Hb Lake in the south and the Cong T a y in the east, with the central part of 434 km2 in area including 775 named islets The surrounding buffer zone lying' along the bay side, following the Highway 18A toward Quang Hanh (Cam PhaTown), has a width of 5-7 km with the sea or mainland as vicinity including the sea part adjoining the Cat Ba National Park 107'50'00 :",""cr::::::::::::::::==~;==-~~~~~~r'~~~r -::~ ~ "~W,,, TSRQPONMLKJIHGFEDCBA D " 'N ~ : a : ,,,"IK G ~ iJI{cbaZYXWVUTSRQPO V J.$ ~ ' ,) " • • " "~ ' I;! ,.- - ld o f utsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ~' i¥ ~o, N S V lm g y I , f (, • tI DI4'~ yxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA o ~ L ," N U tD A"'I ~~ 107"41' ~ D' 20"11' d '" I.H~Mai \ l~~I'====~_==========~==~~~_'='_='_="='_~"::>==========~~ ~~' :r o 20"07' N ~~S~.~~ChL~ong~~~1~~I·I~ 107'50'00 Figure 1, Geological map of the Ha Long Bay and adjacent areas (based on materials ofNguyln C6ng LU(Jnget al /999; Ng6 Quang Toan et al/998 with some revision and supplements)ZYXWVUTSRQPONMLKJIHGF S c a le : 0 0 [R J m ~ I m m W lT l Quaternary: pebble, granule, sand, clay Oligocene-Neogene: conglomerate, gritstone, silty claystone, oil shale, containing Pecoptens lolangcn.l'Is, thickness: 170-400 m Qllerc", cf lobbn Ctcatricosisporites domgensis, Viviparus cf margaryoefonnis; Lower-Middle Jurassic: conglomerate, sandstone, carbonaceous shale containing Anomozomues ( 'omo~ens sp, Tutuella sp., Euesthena sp.; thickness: 1000-1800 m sp., Upper Triassic: conglomerate, gritstone, sandstone, coal seams, silty claystone, containing ('Iathro~enl' memsaoutes, Taentoxeris nib,soniOlde.\', Glossopums indica, Gervillia cf irflata, l Imomtes damdunenst ••; Upper Permian: cherty shale, clay shale, limestone, containing Nankmel/a gratiosus; thickness: 250-300 m 1>11/11/1/, Tikhmella Lower-Middle Devonian: chocolate-coloured sandstone, calcareous silty clay shale, containing' sp, 1£"idelldropsl.\· sp., Vietnamaspis trii, i:'1Iry pinjer cf 1000kll1e""",, Synngopora elji!benm; thickness: 1000-1400 rn, ('ookwmia IT] Upper Silurian' calcareous sandstone, marly shale, limestone, containing Retztella weben, Mesotavosites sp., Nipponophyl/llm sp.; thickness: >600 m ~ Upper Ordovician - Silurian: tuffaceous sandstone, rhythmically interbedded with siltstone and clay shale containing Dcmirastrites triongulans, Prisuograptus minor, M(lIlogro~", sp.; thickness: > 1800 m thickness 2200.J400 m Middle Triassic: tuffaceous sandstone, porphyritic rhyolite, siltstone, clay shale, containing Neoschizodus cf 01'01"" Costaona cf gok#i""" Monophyl/iles sp.; thickness: 1500-1700m Middle-Upper Devonian: limestone, calcaro-chertyshale, containing Slrmgocephal", sp., Palmatolepis trumgulans; thickness: >750 m sp, Meeketlo cf ~feftl'l." OTHER SYMBOLS Product", Lower Carboniferous - Permian: cherty limestone, oolitic limestone, containing Millerella sp., T r iu c it e s ei.toosens», Verheekma v e r b e e k i; thickness: 1000-1100 m .-"30 eleganlula, l- u s t d in e lla ~pper ~onian - ,~,,:er C~rbo~ferous: calcaro-cherty shale,.marly shale containing Q I I ( J I · le n d o lh y r a a ( jj b~ J Strike and dip Fossils: a) mUM; b) flora /" ; Fault Interesting sites on geology According to the suggestion of Dr Hans Friederich, Chief of the Bureau representing the International Union of Conservation of the Nature (Il.K'N) at Hit N9i and the Managerial Commission of the Ha Long Bay, Prof.Dr Tony Waltham of the Trent Nottingham University, UK has been carrying the study on the geology and the limestone karst of the Ha Long Bay (1998) The Ministry of Culture and Information and the National Committee for UNESCO of Viet Nam have sent the record to the World Heritage Committee (WHC) at Paris in 12/1999 ruCN and WHC have sent Prof Eleri Hamilton Smith to the Ha Long Bay for establishing the verifying report on the authenticity of the above record (3/2000) and the 24th plenary session of the WHC at Cairns City of Queensland State, Australia has recognized the outstanding global value on geological history and limestone karstic geomorphology of the Ha Long Bay according to the 151 criterion of the World Heritage Convention and adopted the proposal to inscribe the Ha Long Bay to the World Heritage List with the absolute votes (2/12/2000) Recently, the Prime Minister of Viet Nam has issued the Decision No.l42/2002-TTg on the approval of planning to the year 2020 of preserving and displaying the value of the Ha Long Bay Heritage; in this decision the area of direct study has been determined as 1553 km', in which the Ha Long Bay forms the centre and the area of indirect study including even the Cat Bit Island and the northern part of the Road No.l8A surrounds it composite terrane, which had passed through the processes of evolution, drifting, collision and change during pre-Cambrian - Phanerozoic The majority of the pre-Cambrian and Lower Paleozoic basement is covered and is exposed only in some places around the B~c B9 Gulf, but the Ordovician to recent formations are exposed rather fully on this area Along the Co To Archipelago and T~ Mai uplifted zones Ordovician-Silurian terrigeno-volcanic flyschoid formations of the marginal volcanic arc setting are strongly folded, forming the Quang Ninh Geoanticline which was amalgamated into the Sino-Vietnamese Terrane during the process of collision and Caledonian orogeny Devonian - Upper Paleozoic terrigenouscarbonate sediments lying unconformably upon them, exposed in the northwest of B~c ae Gulf and Hill Phong, Hill Duong, are asymmetrically folded and plunge under the Hl;lLong Bay and Quang Ninh Coast with a sloping attitude Superimposing the above structures, there is the An Chau Intracontinental Rift in the northwest and the Hon Gai, Bao Dill Mesozoic coal-bearing continental grabens which are the products of the Indosinian tecto genetic process, that became more complicated by the impact of the Jurassic Late Cretaceous active continental margin In the top there are Cenozoic structures, such as the Red River Pull-apart Basin, the Hoanh B6 and B~c B9 Gulf grabens which are petroleum- and coal-bearing basins, that were influenced by the sinistral strike-slip movement of the Red River Fault system and the formation of the East Vi~t Nam Sea On the basis of existing materials the authors present briefly the outstanding values on geology of the Ha Long Bay and The above geological settings create adjacent areas and hope that by further worldwide outstanding values on the studies other geological values will be historical geology, limestone karstic certainly discovered.ZYXWVUTSRQPONMLKJIHGFEDCBA geomorphology, marine Quaternary G E O L O G IC A L S E T T IN G S geology and the diversification of geological resources of the Ha Long Bay The Ha Long Bay and adjacent areas and adjacent areas consist of a part of the Sino-Vietnamese VALUES OF H IS T O R IC A L AND China; it is of shallow-sea environment in STRUCTURAL GEOLOGYyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Ha Tuyen - Thanh H6a and becomes deeper The development history of the Earth's crust in the Ha Long Bay is closely related to the regions situated around the B~c B9 Gulf and Southeast China During the pre-Cambrian (3000-750 Ma), the basement of granulite and amphibolite facies exposed in some areas of the Red River Basin, Hainan Island and Kwangtung passed through Late Archean tectonothermal stages of isotopic age as 2930-2840 Ma, Proterozoic ones - 2360-1960 Ma and 1790970 Ma [35], collision and Grenvillian orogeny amalgamating the Cathaysia, Yangtse-Phansipan and Indosinian cratons with one another that were the components of the Rodinian supercontinent existing about 1000 Ma ago [11] Then, the process of rifting took place for developing sedimentary basins, volcanic island arcs and forming the Gondwana Continent in about 550 Ma ago, and through many events a part was separated and accreted to the Asia Plate [11], including the B~c B9 Gulf and adjacent areas N e o p ro te ro zo ic - M id d le P a le o zo ic p e rio d (7 -3 M a ) The similarity between biological provinces, paleomagnetism of Cambrian-Carboniferous geological formations in the Sino-Vietnamese and Indochinese, etc composite terranes situated in the southern hernisprere together with Australia have been proving their Gondwanan origin The sediments containing many kinds of paleontological remains and Phanerozoic magmatic formations having space and time relations forming the islands in the Ha Long Bay and adjacent areas are rock historic pages recording the imprints of geological evolution in the interval from 550 Ma to present days The Cambrian - Early Ordovician sedimentary basin (550-465 Ma) contains many trilobites, brachiopods, etc is largely distributed in North Viet Nam and South and deeper in East Bac B9, Hainan Island, etc After a gap the Co To and T§n Mill forearc basins was formed including tuffaceous flyschoid formations, rich in calkalkaline volcanoclastic materials olistostrom and turbidite with a thickness of over 1800 m, that were linearily strongly folded in NESW trend, containing the graptolitesutsrqponmlk Demirastrites triangulatus, Spirograptus cf regularis, turriculatus, Pristiograptus Monograptus ex gr pandus, etc of Llandoverian and Wenlockian age, EarlyMiddle Silurian (435-425 Ma), but their lower part is possibly of Late Ordovician age [20, 36]; these formations extend to the Yunkai island arc margin, K wangtung, China The sea gradually regressed to the present south for forming shallow shelf sediments: silty sandstone, clayey limestone attributed to the Ki~n An Formation (S34TSRQPONMLK ka) with a thickness of >600 rn dipping northeastwards These sediments contain bottom fauna, such as brachiopods: Retziella weberi, Nikiforovaena vietnamensis, Howellella bragensis, etc., corals: Mesofavosites sp., Xiphelasma sp., Nipponophyllum sp., etc., bivalves: Schizodus kienanensis, Modiomorpha paracrypta, etc of Late Ludlowian to Pridolian, Late Silurian (about 420-413 Ma), similar to the lower basin of the Da River, or Quang Binh of the Indochina Plate, which is near to the South China, Central Asia and East Australia plates [31] The Early-Middle Paleozoic tectonic movement led to orogenic manifestations and magmatism from Middle Cambrian to Middle-Late Ordovician, especially to the process of collision and folding accompanied by granitoid intrusion at the end of Silurian (410cbaZYXWVUTSRQPONMLKJIHGFE ± 20 Ma) forming the Sino-Vietnamese composite terrane, having the continental part enlarging southwards from Silurian to Devonian The Devonian - Early Carboniferous (410-340 Ma) sedimentary basin with the A transgressive section from the continental, subcontinental molassic formation grading upward into terrigenous-carbonate-cherty sediments on the sea shelf lying unconformably upon the Co To Formation (03-S utsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ct) exposed on the Trk Islet, and the Ki€n An Formation (S34 ka) This formation forms a synclinal limb plunging northwestwards under the Ha Long Bay and the Quang Ninh Coast, and in its northeast direction it plunges towards Hill Phong Thuy Nguyen Its lower part has been grouped into the Song C~u Group with the Mia Le, Duong D