重庆石柱-彭水地区下寒武统石龙洞组沉积特征  

Sedimentary characteristics of Shilongdong Formation of Lower Cambrian in Shizhu-Pengshui area of Chongqing

作　　者：何幼斌[1] 蒋蕾 顾志翔[1] 罗慈航 张欣茹 HE Youbin;JIANG Lei*;GU Zhixiang;LUO Cihang;ZHANG Xinru(School of Geosciences,Yangtze University,Wuhan 430100,Hubei)

机构地区：[1]长江大学地球科学学院,湖北武汉430100

出　　处：《长江大学学报（自然科学版）》2023年第1期1-12,共12页Journal of Yangtze University(Natural Science Edition)

基　　金：国家自然科学基金项目“中上扬子地区中二叠世缺氧环境成因模式研究”(41402089);湖北省高校2019年省级大学生创新创业训练计划项目(s201910489034)。

摘　　要：基于野外剖面观察、实测以及室内薄片鉴定和地球化学测试分析资料,对重庆石柱石流村至彭水板凳沟地区下寒武统石龙洞组的岩性特征、沉积相类型及其演化进行了研究。研究结果显示:石龙洞组主要为一套浅水碳酸盐岩沉积,在垂向上自下而上有3个由白云岩-石灰岩构成的岩性组合,自西向东岩性由白云岩为主逐渐变化为以石灰岩为主。研究区沉积期古地貌、古盐度及海平面相对升降变化等共同控制了碳酸盐岩差异发育,整体处于海相环境,以贫氧-缺氧为主。西北区水体深度相对较浅,其周缘发育条带状台缘滩阻碍了海水的正常循环,为局限台地环境,古盐度较高,在干热气候条件下,有利于白云岩的发育。东南区更为临近广海,水体深度相对较大,水体循环受到的影响相对较小,水体古盐度正常,整体处于开阔台地环境,因此以石灰岩为主,白云岩不发育。Based on field section observation, actual measurement, indoor thin section identification and geochemical test analysis data, the lithological characteristics, sedimentary phase types and their evolution of the Lower Cambrian Shilongdong Formation in Shizhu-Pengshui area of Chongqing were investigated.The results show that the Shilongdong Formation, mainly a set of shallow-water carbonate deposits, constitutes three lithologic assemblages of dolomite-limestone from bottom to top in the vertical direction, and the lithology gradually changes from dolomite to limestone from west to east.The paleomorphology, paleosalinity and the relative rise and fall of sea level during the sedimentary period in the study area jointly control the differential development of carbonate rocks.The overall is in a marine environment, donimated by poverty-anoxia.The water depth in the northwest area is relatively shallow, and the development of striped terrace beaches on its periphery hinders the normal circulation of seawater. It is a confined terrace environment with high paleosalinity, which is favorable for the development of dolomite under the dry and hot climate conditions.The southeastern area is closer to the open sea, with relatively large water depth and relatively little influence on water circulation. The water paleosalinity is normal, and the whole area is in the open platform environment.Therefore, limestone is the main part, while dolomite does not develop.

关 键 词：重庆石柱-彭水地区 石龙洞组 岩石学特征 海平面变化 沉积相 

分 类 号：P618.13[天文地球—矿床学]