四川龙门山甘溪泥盆纪生态地层、层序地层与海平面变化  

DEVONIAN ECOSTRATIGRAPHY, SEQUENCE STRATIGRAPHY AND SEA-LEVEL CHANGES IN GANXI, LONGMEN MOUNTAIN AREA, SICHUAN

作　　者：鲜思远[1] 陈继荣[1] 万正权[1] 

机构地区：[1]成都地质矿产研究所

出　　处：《沉积与特提斯地质》1995年第6期1-47,共47页Sedimentary Geology and Tethyan Geology

基　　金：""八五"期间地质矿产部重要基础研究项目;"四川龙门河山泥盆系区域层型剖面"课题

摘　　要：龙门山甘溪剖面是我同泥盆系重要典型部面之一，倍受中外同行关注．本文着重对生态地层、事件地层、层序地层进行研究、为研究全球海平面变化提供区域背景资料．龙门山甘溪剖面含十分丰富的底栖生物化石，从洛赫柯大阶－弗拉斯阶自下而上可识别出２４个腕足动物群落，另外还建立了若干礁复体群落和浮游群落本文对以上群落的特征、性质、分异度、成分、底栖组合及其与沉积环境的关系作了分析和讨沦，并识别了１１个海进海遇事件（生物的或非生物的）本区泥盆系是加里东构造旋回后的第一个沉积盖层，属海平面主体上升和海侵同步条件下的旋回超覆地层，由砂质海岸环境向碳酸盐台地环境推进，构成了区内泥盆纪沉积层序序列的组合特征根据海平面的变化及其相旋回的变迁，划分出６个三级沉积层序；６个沉积层序代表６次海平面的相对升降周期，大致相当于Ｖａｉｌ，Ｐ、Ｒ．（１９７７）划分的三级地层旋回的海平面变化周期（延续时限１—１２Ｍａ），包括４个较大的海平面上升周期与与２个较大的海平面下降周期，即洛赫柯夫期、布拉格晚期至埃姆斯早期．吉维中期及弗拉斯早、中期的海平面上升期与艾费尔期中晚期至法门期的海平面下隆期上述沉积层序特征和平面变化，说明区内泥盆纪台缘断陷盆地的形成经历了由?The Ganxi section in the Longmen Mountain area, Sichuan is a key Devonian section in China. The study is intended to examine the ecostratigraphy, sequence stratigraphy and event stratigraphy for the purpose of delineating the sea-level changes in the study area during Devonian time and providing the regional background data for the study of the global sea-level changes. The Ganxi section abounds in benthic fossils which may be categorized into twenty-four brachiopod communities in the ascending order from the Lochkovian to Frasnian strata. They are: 1. Lingula community, 2. Strophochonetes-Howellella Community, and 3. Orientospirifer- Howellella Community in the Lochkovian-Pragian strata, 4. Strophochonetes-Orientospirifer Community, 5. Howittia-Athyrisina Community, 6. Rostrospirifer,r-Athyrisina Community, 7. Dicoelostrophia-Rostrospirifer Community, 8. Euryspirifer Community, 9. Otospirtifer Xiejiawanensis Community, 10. 'Vagrania ' -Parachonetes Community, 11. Mesodouvillina- Megastrophia Community, 12. 'Otospirifer ' -Athyisina Community, 13. Otospirifer- Lttanquenlla Community, 14. Dexquamatia-Chuanostrophia Community, and 15. Neocoelia Community in the Emsian strata; 16.Zdimir Community and 17. Atrypids-Schizophoria Community in the Eifelian strata: 18. Stringocephahts Community, 19. Independatrvpa- Uncintthts Community, and 20. Leiorhynchus-Emantlella Community in the Giuetian strata; 21. Zhonghuacoelia-Leiorhuvynchus Community, 22, Leiorhynchus Community, 23. Schizophoria- Gvpidula-,Auypa Community, and 24. Cyrtospirifer Community in the Frasnian strata. In addition, a number of compound reefal com.munities and planktonic communities have been established as well. The characteristics, diversities, compositions, benthic associations and their bearings on sedimentary environments are discussed in the present paper. The brachiopod fossils were less developed, with a very low diversity and benthic associations of BAI and BA2 during the Lochkovian stage. Till the Emsian stage, the brachiopods flourished unpre

关 键 词：龙门山 泥盆纪 生态群落 生物事件 沉积层序 海平面变化 

分 类 号：P534.44[天文地球—古生物学与地层学] P731.23[天文地球—地质学]