西秦岭造山带泥盆纪沉积地质学和动力沉积学研究:西秦岭南带泥盆纪裂陷槽盆地、摩天岭地体沉积特征和盆地格局

SEDIMENTARY GEOLOGY AND DYNAMIC SEDIMENT-OLOGY OF THE DEVONIAN STRATA IN THE WEST QINLING OROGENIC BELT: SEDIMENTARY CHARACT-ERISTICS AND FRAMEWORK OF THE DEVONIAN RIFT TROUGH AND MOTIANLING TERRANE IN THE SOUTHERN BELT OF THE WEST QINLING OROGENIC BELT

关键词:  秦岭造山带  泥盆系  沉积地质学  裂陷槽盆地

Key words:  Qinling orogenic belt  Devonian  sedimentary geology  rift trough

摘要:

南秦岭裂陷槽位于中秦岭微板块和摩天岭地体之间。本文根据裂陷槽盆地三河口群和摩天岭地体泥盆系沉积学研究,结合火山作用和生物古地理的研究,探讨该区泥盆纪的盆地格局。三河口群以深水盆地和陆棚沉积为主,内夹拉斑玄武岩和硷性玄武岩,岩石化学和稀土元素的分配型式都反映其处于裂陷槽盆地背景。生物古地理分异也指示裂陷槽盆地的存在。摩天岭地体泥盆系为滨岸-陆棚碎屑岩和陆棚-缓坡碳酸盐沉积,其为扬子板块北部大陆边缘的一部分。

Abstract:

The southern Qinling rift trough is installed between the Qinling mieroplate and Mo-tianling terrane. The stress in this article is put on the stratigraphy,sedimentology,volcan-ism and palaeobiogeography of the Devonian strata in the rift trough and Motianling ter-rane,as well as their depositional systems and basin framework. The Devonian Sanhekou Group in the rift trough consists of metamudstone,silty mudstone and thin-to thick-bed-ded lime mudstone in deep-water basin and shelf environments interstratified with tholeiite and alkali basalt. The chemical analysis and REE distribution patterns of tholeiite and al-kali basalt indicate the existance of the rift trough during Devonian time. The Devonian strata in the Motianling terrane are made up of terrigenous nearshore and shelf deposition-al system,and carbonate ramp and shelf depositional systems. The terrane is interpreted as part of the northern continental margin of the Yangtze plate.