摘要
四、汝阳群、洛峪群陆源碎屑沉积环境 汝阳群、洛峪群及其相当地层,除本区西南部外,以陆源碎屑沉积为主。这些陆源碎屑沉积均不含任何可资确定沉积环境的化石。因而,确定沉积环境只能主要依据:(1)自生矿物,作为浅海相沉积标志的海绿石常见于白草坪组、北大尖组、三教堂组和马鞍山组,嵩山地区马鞍山组内有钙磷酸盐小透镜体;(2)沉积构造组合及其垂向序列;(3)岩石的结构特征。
The spatial distribution of the Ruyang Group and its equivalents,as the Xionger Group,was also obviously controlled by the faults along the basin boundaries.The Euyang Group consists mainly of terrigenous clastic rocks including deltaic,littoral,tidal flat and shallow-marine facies.During the late Buyang age,the carbonate platform developed in the southwestern part of the study basin.The paleoslope inclined from north towards south,and was at a right angle to the strike of facies belts.The depocen-ter extending in NE-NNE direction ran more or less parallel to the basin axis(Fig.4 and 5).During the deposition of the Luoyu Group and its equivalents,a significant change of the basin configuration took place,and both the basin axis and the depo-center were turned to E-W direction.The sedimentary filling was mainly of littoral and shallow-marine terrigenous clasts,but the carbonaceous mudstones and cherts of the relatively deep-water origin were deposited in the southwestern part of the basin(Fig.6).The results of the lighofacies and paleogeographic studies show that the terrigenous clastic materials of both the Ruyang and Luoyu Groups were supplied from the source of the ancient land north of the basin.According to the genetic model of the origin and development of aulacogens proposed by P.Hoffman,J.F.Dewey and K.Burke(1974),the evolution of the Henan-Shanxi basin is discussed in this paper.The Henan-Shanxi Aulacogen was developed from the abandoned arm of a three-armed radial rift system.In its graben stage,at first the Xionger volcanic rocks of the shoshonitic series accumulated,and then the filling of the terrigenous clastic and carbonate deposits of the Ruyang Group followed.During the Luoyu age,the mantle plume died out,and subcrustal contraction and collapse of the graben occurred,thus the Henan-Shanxi Aulacogen came to its downwarp stage.Judging from the genetic relationship between the Henan-Shanxi Aulacogen and the Qinling Geosyncline,the authors believe that the"Qinling Axis"was a block separated from the North China Platform due to the spreading of the active arms of the triple junction.This idea would go far toward clarifying the Proterozoic history of the Qinling Geosyncline.
作者
孙枢
陈志明
王清晨
Sun Shu;Chen Zhiming;Wang Qingehen(Institute of Geology,Academia Sinica,Beijing)
出处
《地质科学》
1982年第1期5-12,共8页
Chinese Journal of Geology(Scientia Geologica Sinica)
