摘要
在南华系钻孔编录与野外剖面观察实测的基础上,结合近年来报道的同位素年龄对渝东南与黔东地区南华系进行了梳理,并对其沉积环境进行了讨论。其中铁丝坳组沉积环境为地堑盆地冰内水道,由数个退积型副层序构成低位体系域沉积。大塘坡组整体为间冰期沉积,一段为二级层序的海侵体系域沉积,见滑塌变形沉积构造,由一系列向上变深的退积型副层序组成;二、三段对应高位体系域,碳质、泥质逐渐减少,砂质含量逐渐增多,发育同沉积变形构造,由一系列向上变浅的进积型副层序组构成。南沱组为冰水沉积,发育滑塌褶皱、滑塌断层,局部见滑塌角砾。大量滑塌构造的发现为研究区南华纪发育一系列北东向的地堑盆地提供了较好的佐证。沉积环境的横向对比表明,研究区存在一个北西向南东倾斜的海底缓坡,为锰矿的沉积提供了良好的储集场所。
This paper discusses the sedimentary environment of Nanhua System on the basis of substantial and detailed drilling catalogs and observations of sections which are part of the Nanhua System,by checking up the stratum in the southeast of Chongqing and east of Guizhou combining with isotopic age reported in recent years.The depositional environment of Tiesi′ao Formatiom is inner ice tunnel of graben basin,trough cross-bedding and tabular cross bedding have been found in Tiesi′ao Formatiom,which is the LST.Most of dropstones which is the sign of glacial deposition have been destroyed.The first period of Datangpo Formatiom is transgressive system tract constituted by a series of retrograding sequence and slump deformed structures have been found in it.The carbonaceous and shale reduced gradually upwards in second and third period of Datangpo Formatiom which is HST composed by a series of retrogradation type parasequence set shallowing upward.Slump folds,slump faults and breccia have been found in Nantuo Formation which is glaciofluvial deposit.Plenty of slump bedding found in this area is the evidence of series of northeastwards pregraben basin in Nanhua System.Contradistinction of the regional sedimentary environment indicate that gentle slope which is leaning to the south east widespread in Nanhua System.The specific environment provides a good space for the enrichment of manganese.
出处
《地质科技情报》
CAS
CSCD
北大核心
2015年第2期27-35,共9页
Geological Science and Technology Information
基金
中国地质调查局项目(12120113050300
12120113049100
1212011220412)
国土资源部公益性行业科研专项(201411051)
关键词
南华系
沉积环境
体系域
缓坡
Nanhua System
sedimentary environment
sedimentary structures
gentle slope
