川东石炭系碳酸盐岩沉积环境探讨  

DISCUSSION ON THE SEDIMENTARY ENVIRONMENT OF CARBONIFEROUS CARBONATE ROCKS IN EAST SICHUAN

作　　者：钱峥[1] 

机构地区：[1]石油大学资源科学系

出　　处：《天然气工业》1999年第4期19-22,共4页Natural Gas Industry

基　　金：国家"九五"攻关项目

摘　　要：依据岩石学、古生物及地球化学沉积相标志的研究，川东石炭系沉积环境的演变经历了蒸发膏湖—咸化泻湖—陆表海三个主要阶段。川东地区早石炭世末期，受中国南方发生较大规模海退的影响，黄龙组沉积早期（Ｃ２ｈｌ１）受古高地的阻隔，发育膏湖沉积：由于干旱炎热的气候，水体蒸发量大于注入量，水体循环较差，沉积了大面积的白云岩和石膏沉积。黄龙组沉积中期（Ｃ２ｈｌ２）以咸化泻湖沉积为特点，以白云岩沉积为主，表现为多个自下而上由粒屑云岩—粉微晶云岩—干裂角砾云岩组成的向上变浅序列的叠合，具明显的旋回性，反映了高能浅滩与间歇性暴露地表交替出现的结果。黄龙组晚期（Ｃ２ｈｌ３）海平面上升，江南古陆没入海平面之下，扬子准地台形成陆表海环境，属开阔台地环境的浅水沉积，石灰岩类普遍发育，以有孔虫、红藻、珊瑚、腕足、苔藓等为主组成的生屑灰岩大量出现，表明沉积水体较为通畅。Through studying the sedimentary facies marks of petrology,paleontology and geochemistry,it is shown that the evolution of the sedimentary environment of Carboniferous carbonate rocks in east Sichuan has gone through three main stages:evaporate gypsum lake,saline lagoon and epicontinental sea.In the early depositional stage of Huanglong formations(C2hl1),the gypsum lake deposition has developed due to the separation of palaeotopographic high and the influence of the largescale regression in South China in the end of early Carboniferous epoch in east Sichuan and an extensivearea dolomite and gypsum sediments have deposited.Because the climate was dry and scorching,the quantity of evaporative water was greater than that of pouring water and the water circulation was bad.In the middle depositional stage of Huanglong formation (C2hl2) (mainly are saline lagoon and dolomite deposits),there were several suprapositions of the successions,which are composed of allochemical dolomite,microcrystal dolomite and desiccationbrecciated dolomite from bottom to top and shallows upward,having a obvious cyclicity and reflecting a result of the alternate appearance of highenergy bank and surface's intermittent exposition in air.In the late depositional stage of Huanglong formation(C2hl3),the Jiangnan old land has been inundated under sea level due to sea level raising and the Yangzi Paraplatform has become an epeiricsea environment,belonging in the shallow water deposit of open platform environment.The limestone is developed widespreadly and there is a large number of the bioclastic limestones composed of foraminifera,red algae,coral,brachiopoda and bryophyte,etc., which shows that the water body deposited is unobstructed and the salinity is normal.

关 键 词：石炭系 碳酸盐岩 沉积环境 川东地区 

分 类 号：P588.245[天文地球—岩石学] P534.45[天文地球—地质学]