1996b outlines of stratigraphy and remarks on paleogeography of devonian in southeast asia

ISSN 0866 - 7381 Journal of SPECIAL ISSUE No 7-8 Se ries B 1996 TpPR COCEEDINGSOFTHEINTERNATIONALSVTVIPOSIUM PR GEOLOGY OFSOUTHEAST ASIA ANDADJACENT AREAS is UNESi w Li o O ■ o ' 32 * 1- 9November 1995, Hanoi ' GEOLOGICAL SURVEYOF VIETNAM HANOI Journal of GEOLOGY Series B, No.7-8/1996 Thirty sixth year E D IT O R IA L O F F IC E Phạ m Ngũ Lão, Hà Nộ i Tel: 84 4.8 ( 253 110, 246 461, 352319) Fax 84.4 254 734 EDITORIAL BOARD Editor - in - chief: TRAN VAN TRỊ Members: LÊ ĐỨ T AN, LÊ VAN TRẢ Ọ , NGUYEN GIAO, NGUYEN KHẮ C VINH, NGUYEN NGHIÊM MINH, NGUYỄ N TIEN THÀNH, NGIJYEN TRỌ NG YÊM, NCHJYEN x u â n b a o , p h m v ầ n AN, PHAN C ự TIẾ N, PHAN TRUỜ NC TIIỊ ,TÀNG MlJỜ I,Tổ NG DIJY TILANII,TRẰ N MINH THẾ , VÕ CÔNG NGHIỆ P, VŨ KHÍJC ( Deputy Hditor - in - chief),v ũ NGỌ C HẢ I (Deputy Editor - ill - chief), Secretary: BÙI Đ ÍJt THẢ NG CONTENTS PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM ON GEOLOGY OF SE ASIA AND ADJACENT AREAS, HÀ NỘ I NOV 1995 ] PHẠ M KIM NGÂN, LIJƠ N(Ỉ Hồ NG IIIỌ c • Cambrian and Ordovician sediments in Việ t Nam TỐ NG DIJY THANH, HOIJ HONGFF.I, TẠ HỒ PHI JONG, Ní ỉ IIYỄ N IlfJtJ HIJNG, ĐOÀN NI1Ậ T TRIJONG Outlines of stratigraphy and remarks on paleogeography of Devonian in Southeast Asia DIC'KINS J.M Permian and Triassic events in Việ t Nam and implications for economic geology NGUYÊN KINH Q u ố c , LÊ HIJN(Ỉ Early Mesozoic feiTohypersthene - bearing volcano plutonic rocks from association group of klionlanite - dellenite - baclieitc in Northeast Việ t Nam NGÔ THỊ PHUỢ NG Petrology and evolution of the formation of Permian - Triassic mafic ultramafic associations in North Viộ t Nam BROOKFIELD M.E Reconstruction of Western Sibumasu 7.LÊ DZUY BÁCH Precambrian folded complexes of SH Asia 8.IIANTORO W.S., LAFONT R., HIED A s., HANDAYANI L., SEBOWO E., HADIWISASTRA S Ilolocene to Recent vertical movement in Indonesia: study 011 emerged coral reef NGUYÊN ĐÌNH XIJYEN, TRAN THỊ MỸ THẠ NH Estimation of recurrence period of laree earthquakes in a given place following the long - term variation of seismic activity 10 35 40 59 65 81 93 115 JOURNAL OF GEOLOGY, SERIES B, № 7-8/1996 10 TẠ HOÀ PHUƠ NG, BAIJDIJ - SIJIRE V., LÊ VẦ N GIANG Scolecodonts from the Bail Thiuig Fonnation (Lower Devonian) in Khao Lộ c - Quả n Bạ area, Hà Giang Province 11 NGUYÊN HOÀN, NGUYÊN NGOC, NCỈ UYÊN HŨƯ c Main pe riods of paleogeographic evolution of the coastal zone during Pliocene - Quaternary in Việ t Nam 12 NGUYÊN ĐÌNH MỘ C, LÉON DEJONGHE Les filons de quarts stibine de cẩ in Phả , province de Quả ng Ninli, NE du Việ t Níun 13 NGƠ VẢ N BIJtl, PHẠ M VÀN NGỌ C, HOÀNG HŨtJ QUÝ Poss ibilities of applying modem magneto - telluric method to geothermal potential assessment through defining the reservoir and hot dry rock structure zone CONTENTS OF JOURNAL OF GEOLOGY, SFRIHS A, 1996 121 127 133 139 147 Proceedings of the IGCP Symposium on Geology of SE Asia, H anoi, M /1995 Journal of GEOLOGY Series B, No 7-8/1996, p 10 OUTLINES OF STRATIGRAPHY AND REMARKS ON PALEOBIOGEOGRAPHY OF DEVONIAN IN SOUTHEAST ASIA T6ng-Dzuy Thanh*, Hou Hong-fei**, Tạ Hoà Phư ng* Nguyễ n Hữ u Hùng***, Đoàn Nhậ t Trư ng*** * Việ t Nam National University, Hanoi 90, Nguyễ n Trãi Road Đố ng Đa, Hà Nộ i Việ t Nam ** Institute of Geology 26 Baiwanzhuang Road Beijing 100037 China *** Institute of Geology and Mineral Resources Thanh Xuân Đố ng Đa, Hà Nộ i Việ t Nam Abstract.TVỉ e exposures o f Devonian rocks are widespread in Southeast Asia — in South China (Guangxi, Yunnan Provinces), 'Việ t Nam, Laos, Thailand and Malaysia This paper is only a first attempt at correlating the Devonian stratigraphy in this region The Devonian stratigraphy and containing faunas will be examined in the frame o f the following suitable terraries Tile South China and North Việ t Nam terrane includes the territories ofGuangxi, East Yunnan (South China) and North Việ t Nam up to the Northeast bank o f the Sông M ã fault The Indochina terrane com­ prises the North o f Central Việ t Nam, Laos and East Thailand The Shan - Thai terrane comprises Western Yunnan, Shan States o f Burma, mainland o f Thailand and West Malaysia The main stratigmphic units from Lower to Upper Devonian and their fauna assemblages are presented and correlated in the paper In most cases o f South China, Northeast Việ t Nam areas a gap took place in Siluriari-Devonian boundary sequences The lowermost formation o f Lower Devo­ nian consists o f the rocks o f "Old Red Sandstone" facies Lianhuashan Formation in South China, Sika Formation in Northeast Việ t Nam A similar formation takes place in the Mid-Central Việ t Nam —Tân Lâm Formation The continuous Siiurian-Devonian boundary can be expected in the Sông Cả Sections (North o f Central Việ t Nam and Northeast Laos), in West Yunnan; North arid Northwest Thailand - East Burma; in Peninsula Thailand and Malaysia In most cases o f these sections the Lower Devonian consists mainly o f shale, mudstone with more or less mixture o f carbonate components containing pelagic fauna The Middle Devonian (sometimes from Emsian) in most cases consists o f fossiliferous carbonate facies A short gap took place in the interval o f Middle Devo­ nian in Northeast Việ t Nam and South China The continuous Devonian - Carboniferous boundary can be observed in South China (for example Nanbancun section in Guangxi), North Việ t Nam and in some section o f Indochina terranes such as East Thailand, Central Việ t Nam Meanwhile a gap took place in West Yunnan, North Thailand and others The most special fauna is the one o f South China and North Việ t Nam terrane in which Lower Devonian contains a great number o f endemics o f diverse benthic groups In spite o f that, the common taxonomic genera show the closeness o f Devo­ nian fauna o f the Southeast Asia region and the European ones Some Australianlike fauna elements were also found in Southeastern Asia, but at present it is prema­ ture to conclude that a part o f this region was derived from Gondwana 10 INTRODUCTION The Devonian rocks are differently studied in Southeast Asia In South China (Guangxi, Yunnan Provinces), Việ t Nam and Laos they are widespread and attract a great number of works of geologists The exposures of them in Thailand and Malaysia are also studied and identified by geologists from dif­ ferent countries In Cambodia there are only the supposed Devonian rocks According to the existing data the Devonian of these re­ gions may be examined in the following suit­ able teư anes (Fig.l) - South China and North Việ t Nam terrane Devonian rocks are widespread in Guangxi, East Yunnan (China) and North Việ t Nam In the tectonic aspect these areas are considered as the main parts of the South China block In this paper the Sông Mã fault is taken as the southern lim it of it, instead of the Red River (Sông Hồ ng) one in the con­ ceptions of the other authors (Fig.) Practi­ cally the Red River (Sông Hồ ng) fault plays a very important role in geology of region in Cenozoic, but there is not the differentiation in the marine facies and the fauna of Devo­ nian in North Việ t Nam (up to the Sông Mã suture) The role of the latter in Devonian is distinguished as the clear lim it between the North and the Central Việ t Nam - Indochina terrane This terrane spreads from the territories of the North part of Central Việ t Nam toward to Laos and East Thailand Cambodia is also considered as a part of this terrane - Shan-Thai terrane The Devonian exposures are observed in W est Yunnan (China), Shan States of Burma, main land of Thailand and its peninsular The Devonian of West Malaysia is also examined in the frame of this terrane Remarks on paleobiogeography of the region will also be presented, the available data show the closeness of Devonian fauna of Southeast Asia and the European ones STRATIGRAPHIC DATA SOUTH CHINA AND NORTH VIỆ T NAM TERRANE North Việ t Nam (Table 1) Lowermost Lower Devonian In North Việ t Nam the Lowermost Der vonian succession begins with Red Beds (Si Ka Formation) in the Northeastern mountain area and with marine deposits in the North­ western one (Iridistrophia praew nbraculum Beds) In more general stratigraphic classifi­ cation of the Devonian in Việ t Nam, these units are grouped together as the Si Ka Re­ gional Stage (Table 1) The Si Ka Formation consists of purplish red conglomerates, sandstones, shales and marls in some sections, which overlie the Cambrian or Ordovician unconformably Some plant remains have been determined as Bytrotrephis aff antiqua and fishes are refered to Yunnanolepiformes and Polybranchiaspis cf gracilis (Tong-Dzuy Thanh & Jan­ vier 1987) This formation is correlated with the Lianhuashan Formation and the Lower part of the Cuifengshan Formation of South China (Tong-Dzuy Thanh, 1980, Tong-Dzuy Thanh et al 1988) It should be compared with the Old Red Sandstone of Western Europe and may be assigned to Lochkovian (Gedinian) The Iridistrophia praeumbraculum Beds are the lowermost marine strata of the Lower Devonian in the Northwestern mountain area of North Việ t Nam They consist of black shales in the Sông Mua Formation (thickness over 1800m) in the lower basin of Sông Đà River The fossils are poor and have been collected only in the middle level of this for­ mation: Corals — Parastriatopora cf rzonsnickajae, Brachiopods — Iridistrophia praeumbraculum, M esodouvillina aff subinterstrialis, Platyorthis cimex and Crinoids — Schvschcatocrinus astericus These Iridistrophia praeumbraculum Beds are considered as the lowermost level of the Devonian in the Northwestern mountain area and can be as­ signed to the Lochkovian The Silu­ rian/Devonian boundary could be probably present in the interval between the underlying Bó Hiề ng Formation (Silurian) and the level of Parastriatopora cf rzonsnickaiae in these examined Beds Figure Devonian exposures'in Southeastern! Asian terranes South China - North Việ t Nam terrane: 1 Guangxi, 12 East Yunnan, J Northeast of North Việ t Nam, 14 Northwest of North Việ t Nam Indochina terrane: Central Việ t Nam (2 Ia , Cù Bai sections, Ib ■ Rào Cả i sections, lc Sông Cả sections) 2 Central Laos J , ■ West Laos - East Thailand, Ị Cambodia Shan - Thai terrane: 31, West Yunnan, ■ Shan States, 3 Northwest Thailaruỉ , 34 Peninsula Thailand and Malaysia fossiliferous undetermined Devonian 12 rare fossils Bắ c Bun Regional Stage The Bắ c Bun Regional Stage was estab­ lished on the basis of the coư elation of m a­ rine deposits yielding the Howittia wangi As­ semblage (Hysterolites wangi in the previous works) This unit comprises the Bắ c Bun Formation in the Northeastern mountain area, the upper part of the Sông Mua and the m id­ dle part of the Nậ m Pi a Formation in the Northwestern mountain area and other equivalents (Table 1) They consist mainly of black muddy shales with intercalation of fine­ grained sandstone and marls, limestone lenses in some sections The most characteristic fossils are Brachiopods — Howittia wangi, Howellella mercuri, Cymostrophia stephani, Chonetes mansuyi, Protathyris sp., Bivalves - Mytilarca (Plectomytilus) oviformis, Corals in the upper part — Favosites subnitellus, Squameofavosites kolymensis, Thamnopora incerta Fish fossils have been collected from Eastern area of North Việ t Nam, in the lower part of this unit —Polybranchiaspis sp., Szeaspis sp., Yunnanolepis bacboensis, Y deprati, Chuchinolepis dongmoensis, Vanchienolepis langsonensis, Youngolepis sp (Tong-Dzuy & Janvier 1990) Recently the fish fossils of "South Chinese" types {Songdalepis pustolatus) are collected and described from this stage in the downstream Sông Đà River, probable in the higher level than in the East­ ern area (Janvier et al 1996) The Bắ c Bun Regional Stage yielding the Howittia wangi fauna is probably Early Pragian in age Mia Lé Regional Stage By its abundant fossils this Regional Stage is the most characteristic unit among the Devonian strata in North Việ t Nam It comprises a combination embracing all for­ mations and beds characterized by the Euryspirifer tonkinensis fauna such as Mia Lé, Bả n Nguồ n, Đạ i Thi Formations, Upper part of Nậ m Pìa Formation, Lower part of Dư ỡ ng Độ ng Formation and others (Table 1) Irs stratigraphic sections consist of shales, fine­ grained sandstones and marls, sometimes with limestone interbeds or lenses In the Northwestern mountain area the terrigenous components increase in the sequences while the carbonate components are more abundant in the Northeastern mountain area In the Hạ Lang region and the northeastern coastal land this unit consists only of terrigenous rocks The characteristic F.iiryspirifer tonkinensis fauna is the most diverse Devo­ nian fauna assemblage in North Việ t Nam and South China Over 300 species of various benthic groups have been determined and de­ scribed in North Việ t Nam, among them Brachiopods and Corals are the most abun­ dant Apart from numerous endemic species many Mediterranean ones are found in the association of this E uryspirifer tonkinensis fauna, such as Corals — Favosites styriacus, Squameofavosites cechicus, Thamnopora incerta, Roemeripora bohemicus, Heliolites barrandei, H praeporosus, Holmophyllum holmi, Brachiopods — Acrospirifer primaevus, Leptaenopyxis bouei, H ow ellella m ercuri etc On the whole, the generic taxa of the tonkinensis fauna are as follows: Stromatoporoids — Anostylostroma, Atelodictyon, Parallelostroma, Plectostroma, Praeidiostroma, Simplexodictyon, Stelodictyon, Stromatopora, Syringostromella, Vicinustachyodes, Trupestostroma; Tabulate — Fossopora, Favosites, Emmonsia, Squameofavosites, Riphaeolites, Echyropora, Cladopora, Gracilopora, Striatopora, Thamnopora, Parastriatoppora, Yacutipora, Roemerpora, Alveolites, Crassialveolites, Caliapora, Coenites, Tyrganolithes, Syringopora, Thecostegites, Heliolites, Paraheliolites, Chaeteies, Chaetetipora; Rugoses — Tryplasma, Holmophyllum, Microplasma, Glossophyllum, Phollidophyllum, Cysticonophyllum, Cyathactis, Evenkiella, Pseudozonophyllum, Dialythophyllum, Zelolasma, Rhyzophyllum; Brachiopods —Acrospirifer, Aceptalium, Athyris, Athyrisina, Atrypa, Desquamatia, Aulacella, Chonetes, Cymostrophia, Dicoelostrophia, Douvillina, Euryspirifer, Glossinotoechia, H ow ellella, Howittia, Indospirifer, Leptaena, Letaenopyxis, Levenella, Megasirophia, M eristella, Parachonetes, Parastronella, Pletorhyncha, Pugnacina, Schellwienella, Stropheodonta, Thiemella, Uncinulus, Undispirifer etc ; Bivalvia Modiolopsis, M ytilarca, Pteria (.Actinopteria), Pterinea (Pterinea), Pterinea 13 zo p z o s co eCd 3cd * £ u« « *o E jò Ê ^ ôd c/a -*ô -e c cOX) Mu Ê -S ãĐ 5; soc -i * to a) in tW g S n o £a ^- E Ä O c/) zo zo < — s