Paleoenviromental Significance of Trace Fossils in Tempestite of Qilang Fm.(Middle Ordovician)of Northwestern Tarim Basin in China

FANG Guo qing; LIU De liang

The Qilang Formation of Middle Ordovician in northwest Tarim basin is composed of laminae marl and laminae limestone with abundance graptolites and trilobites.This kind of marl and limestone thin alternation is typical L-M (limestone-marl) cycle.There are about thirty beds of distal calcareous tempestites in Middle-Upper Qilang Formation.In the plane and bottom of the tempestites ten trace fossils were found and they are： Belorhape, Circulichnus, Dendrichnus,Gordia, Granularia,Megagrapton,Phycodes,Planolites,Protopaleodictyon and Rhabdoglyphas. Because of abundance of Phycodes and Magagrapton,these trace fossils can be named Phycodes-Magagrapton assemblage which are predominant in fodinichnia and shape of ramification,and belong to Zoophycos ichnofacies proposed by Seilacher.This assemblage represent quiet lower energy sedimentary environments under main storm wave level.Based on the fact that event deposition has close relation to the trace fossils,it is believed that Phycodes-Megagrapton assemblage can be a fine auxiliary marker to judge distal tempestite and to differentiate the e vent and normal limestone.

1. Lanzhou Institute of Geology,Chinese Academy of Sciences,Lanzhou 730000;

2. Department of Earth & Space Sciences,China Science and Technology University, Hefei 230026

Received Date: 1999-05-05

Publish Date: 2000-03-10

Key words:

Abstract: The Qilang Formation of Middle Ordovician in northwest Tarim basin is composed of laminae marl and laminae limestone with abundance graptolites and trilobites.This kind of marl and limestone thin alternation is typical L-M (limestone-marl) cycle.There are about thirty beds of distal calcareous tempestites in Middle-Upper Qilang Formation.In the plane and bottom of the tempestites ten trace fossils were found and they are： Belorhape, Circulichnus, Dendrichnus,Gordia, Granularia,Megagrapton,Phycodes,Planolites,Protopaleodictyon and Rhabdoglyphas. Because of abundance of Phycodes and Magagrapton,these trace fossils can be named Phycodes-Magagrapton assemblage which are predominant in fodinichnia and shape of ramification,and belong to Zoophycos ichnofacies proposed by Seilacher.This assemblage represent quiet lower energy sedimentary environments under main storm wave level.Based on the fact that event deposition has close relation to the trace fossils,it is believed that Phycodes-Megagrapton assemblage can be a fine auxiliary marker to judge distal tempestite and to differentiate the e vent and normal limestone.

HTML

Reference (17)

[1]	Einsele G.Limestone-marl cycles(periodites)：diagnosis,significance,causes：an overview〔A〕.In：Einsele G, Seilacher A，eds.cycles and events stratigraphy〔C〕. Springer-Verlag,Berlin. 1982.3～18
[2]	Einsele G.Limestone-marl alternation：an overview〔A〕.In：Einsele G, Ricken W, Seilacher A,eds.Cycles and events in stratigraphy〔C〕.Springer-Verlag,Berlin. 1991.23～47
[3]	周志毅，陈丕基.塔里木生物地层和地质演化〔M〕.北京：科学出版社，1991
[4]	周志毅，林焕令.西北地区地层、古地理和板块构造〔M〕.南京：南京大学出版社，1995
[5]	Aigner T.Calcareous tempestites：storm dominated stratification in Upper Muschelkalk limstones(Middle Trias,SW-German)〔A〕.In：Einsele G,Seilacher A.eds.Cycles and events stratigraphy〔C〕. Springer-Verlag,Berlin.,1982.180～198
[6]	方国庆，王多云，张晓宝.甘肃天祝斜壕地区上奥陶统远源钙质风暴岩的发现[J].地层学杂志，1994，18(4)：296～298
[7]	Wu X.Storm generated depositional types and associated trace fossil in Lower Cretaceous shallow marine carbonates of Three Cliffs Bay and Ogmore-by-Sea,South Wales〔J〕. Palaeograph, Palaeoclimatology, Palaeoecology,1982，39：187～202
[8]	Pemberton S G ,Frey R W.Ichnology of storm-influenced shallow marinesequence：Cardium Fm.(U.Cret.) at Seabe,Alberta〔A〕.In： Stott D F,Glass D J, eds.The Mesozoic of Middle North America〔C〕.Canadian Society of Petroleum Geologists Memoir，1984，9：281～304
[9]	Pemberton S G.Ichnology and event stratigraphy：the use of traces fossils in recognizing tempestites.In：Applications of ichnology to petroleum exploration〔R〕.SEPM Core Workshop No.17,Calgary.1992.85～118
[10]	Seilacher A,Aigner T.Storm deposition at the bed,facies,and basin scale：the geologic perspective〔A〕. In：Eins ele G，Ricken W ,Seilacher A, eds.Cycles and events in stratigraphy〔C〕. Springer -Verlag,Berlin：1991.249～267
[11]	吴贤涛，胡斌，王冠中等.豫西焦作地区上石炭统浅海碳酸盐岩中的风暴沉积〔J〕.沉积学报，1987，5(4)：1～13
[12]	Frey R W, Seilacher A.Uniformity in marine invertebrate ichnology〔J〕. Lethaia,1980，13：183～207
[13]	Einsele G,Seilacher A.Distinction of tempestites and turbidites〔A〕. In： Einsele G,Ricken W, Seilacher A,eds.Cycles and events in stratigraphy 〔C〕.Springer -Verlag,Berlin.1991.377～382
[14]	Seilacher A.Paleontological on turbidite sedimentation and erosion〔J〕.Journal of Geology,1962，70：227～234
[15]	晋慧娟，李育慈.浙西上奥陶统于潜组Spirodesmos遗迹组合的环境意义〔J〕.地质科学，1998，33(3)：282～289
[16]	晋慧娟，李育慈.准噶尔盆地西北缘石炭纪生物成因的沉积构造研究〔J〕.科学通报，1998，43(1)：1888～1891
[17]	张国成，李继亮.东喀拉昆仑北坡三叠纪复理石中遗迹化石及地质意义〔J〕.地质科学，1998，33(3)：257～266

Paleoenviromental Significance of Trace Fossils in Tempestite of Qilang Fm.(Middle Ordovician)of Northwestern Tarim Basin in China

Abstract

References

Proportional views

通讯作者: 陈斌, bchen63@163.com

Article Metrics

Proportional views

Related