内蒙古乌拉特前旗佘太镇中上奥陶统岩石学特征及其沉积环境  

PETROLOGICAL CHARACTERISTICS AND SEDIMENTARY ENVIRONMENTS OF THE MIDDLE-UPPER ORDOVICIAN IN SHETAI TOWN OF URAD FRONT BANNER, INNER MONGOLIA

作　　者：张秀莲[1] 王英华[1] 潘荣胜 

机构地区：[1]北京大学地质系

出　　处：《地质学报》1991年第2期154-165,T001,共13页Acta Geologica Sinica

摘　　要：华北地台腹地大多数地区都缺失晚奥陶世地层,佘太镇白彦花山剖面则是近年来新建立的华北地台最北缘的一个上奥陶统标准剖面,该剖面的建立直接涉及到华北地台北界的确定和对地台演化历史的认识。该区中奥陶统岩石类型及沉积环境与地台腹地显著不同,后者几乎全部为地台型沉积,而该区则多次出现斜坡沉积。本文重点讨论了该区上奥陶统地层的岩石学特征及其沉积环境,为该剖面的建立提供了进一步的理论支持,并填补了这方面的空白。Ordovician strata are widespread in the North-China platform, but the Upper Ordovician is absent in most of the platform. Therefore it had been considered for quite a long time that the platform is devoid of Upper Ordovician strata. The Baiyanhuashan section at Shetai Town is a type section of the Upper Ordovician established in recent years on the northernmost margin of the North-China platform. The detailed study of petrography and lithofacies palaeogeography in this paper indicates that the strata at Baiyanhuashan are greatly different from the Middle Ordovician strata of the hinterland of the platform not only in palaeontologic groups but also in petrographic types and palaeoenvironments. The latter are dominated by micritic limestone and penecontemporaneous dolomite formed chiefly in supratidal and subtidal low-energy zones, whereas the former are composed mainly of grain or grain-bearing limestone and late-penecontemporaneous dolomite deposited primarily in intertidal, subtidal low-energy and high-energy zones and open sea environment. The conclusions drawn in this paper provide a further theoretical support to the establishment of the Upper Ordovician standard section.

关 键 词：岩石学特征 地层 晚奥陶世 内蒙古 

分 类 号：P534.42[天文地球—古生物学与地层学]