摘要
通过系统分析贺兰山地区三叠系的沉积特征,结合研究区盆地构造属性以及物源研究的最新成果,以探究贺兰山地区三叠世盆地演化的具体过程。研究后认为,研究区纸坊组相较于石千峰组物源供给充足、降水充沛,普遍发育辫状河沉积,荒草滩一带存在辫状河三角洲沉积,延长组一段至三段总体发育冲积扇和辫状河沉积,至延长组四段、五段,则以辫状河三角洲和湖相沉积为主。根据三叠系沉积相空间展布特征可知,研究区纸坊组、延长组一段至三段沉积相自西北向东南连续相变,此时与鄂尔多斯盆地完全连通;延长组四段、五段沉积相空间展布格局发生明显变化,且与鄂尔多斯盆地在东南大水沟一带连通,总体呈半连通态势。充足的物源供给、充沛的降雨以及盆地早期快速沉降是上三叠统延长组形成巨厚沉积的必要条件。从中三叠统纸坊组红层的逐渐减少到上三叠统充沛的降雨反映了整个贺兰山地区乃至华北板块西部古气候条件的快速变化,反映了古亚洲洋闭合对区域古地理、古气候的显著影响。
The specific process of the evolution of the Triassic basin in the Helanshan area has long been controversial.The temporal and spatial evolution of sedimentary features is an important means to solve this problem.However,the degree of sedimentary evolution is relatively low.Based on the systematic analysis of the sedimentary characteristics of the Triassic in Helan Mountains and the latest research results of basin tectonic properties and provenance in the study area,it is considered that in the depositional period of the Zhifang Formation,which was dominated by braided river sediments,the provenance supply and precipitation is more abundant than that of the Shiqianfeng Formation in the study area.Alluvial fan and braided river deposits are generally developed in the First to Third sections of Yanchang Formation,and Braided River Delta and lacustrine deposits are dominant in the Fourth and Fifth sections of Yanchang Formation.According to the spatial distribution characteristics of Triassic sedimentary facies,it is considered that the sedimentary facies of Zhifang Formation and the First to Third sections of Yanchang Formation changed continuously from northwest to southeast.At this time,the Helanshan Basin was completely connected with the Ordos Basin.The spatial distribution of sedimentary facies of the Fourth and Fifth sections of Yanchang Formation has changed obviously,it issemi-connected with the Ordos Basin in the southeastern Dashuigou area.Adequate source supply,abundant rainfall and rapid basin subsidence are the necessary conditions for the formation of thick deposits in the Yanchang Formation of the Upper Triassic.From the transform of gradual decrease of red beds in the Middle Triassic Zhifang Formation to the abundant rainfall in the Upper Triassic,we consider the paleoclimate conditions in the Helan Mountains,even in the western part of the North China Plate have changed sharply.
作者
李蒙
李文厚
赵红格
任战利
王星
段玉良
LI Meng;LI Wenhou;ZHAO Hongge;REN Zhanli;WANG Xing;DUAN Yuliang(Depertment of Geology/State Key Laboratory of Continental Dynamics,Northwest University,Xi′an 710069,China;Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266071,China)
出处
《西北大学学报（自然科学版）》
CAS
CSCD
北大核心
2019年第5期745-754,共10页
Journal of Northwest University（Natural Science Edition）
基金
西北大学大陆动力学国家重点实验室科技部专项项目(BJ08133-14,BJ081334-2)
国家自然科学基金资助项目(41330315,40902032)
国家科技油气重大专项项目(2011ZX05023-001-002)
中国地质调查局矿产资源调查评价项目(121201011000150014)
关键词
贺兰山
三叠纪
沉积演化
Helan Mountain
Triassic
sedimentary evolution
