川中地区下寒武统沧浪铺组下段碳氧同位素特征及其地质意义  

Carbon and oxygen isotope characteristics of Lower Cambrian Canglangpu Formation in central Sichuan and their geological significance

作　　者：马腾霄 和源 朱利东[1] 杨文光[1] 曹志超 罗紫云 严威 周刚[2] 龙虹宇 黄茂轩 陈曦 钱红杉 MA Tengxiao;HE Yuan;ZHU Lidong;YANG Wenguang;CAO Zhichao;LUO Ziyun;YAN Wei;ZHOU Gang;LONG Hongyu;HUANG Maoxuan;CHEN Xi;QIAN Hongshan(Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;Research Institute of Petroleum Exploration and Development,PetroChina Southwest Oilfield Company,Chengdu 610041,China;College of Earth Science,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学沉积地质研究院,成都610059 [2]中国石油西南油气田分公司勘探开发研究院,成都610041 [3]成都理工大学地球科学学院,成都610059

出　　处：《成都理工大学学报（自然科学版）》2023年第2期187-199,共13页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国石油西南油气田公司勘探开发研究院科技项目(JS2021-077)。

摘　　要：探讨川中地区早寒武世沧浪铺早期古海洋环境特征。对川中地区沧浪铺组钻井资料、镜下薄片以及65个碳酸盐岩样品的碳、氧同位素进行了测试分析。剔除无效数据后,结果表明,沧浪铺早期δ13 C V-PBD值为-3.4‰~-0.4‰,平均值为-1.4‰;δ18 O V-PBD值为-10.0‰~-5.9‰,平均值为-8.2‰。纵向上,碳同位素值整体呈负漂移,具有先升高后降低的趋势,且底部及中上部变化幅度较小,顶部波动范围大。古海洋环境分析结果显示川中地区沧浪铺组下段古海水平均盐度为33.6‰,古海水盐度在沧浪铺早期较低,晚期较高,与海平面波动明显有关,盐度指数和盐度低值可能由陆相淡水混入导致。古海水温度为11.6~29.6℃,平均为21.3℃。沧浪铺组下段沉积早期温度相对较高,晚期温度波动频繁,且有明显降低的趋势。Based on the drilling data of Lower Cambrian Canglangpu Formation in central Sichuan,combined with the study of microscopic thin section identification and carbon and oxygen isotope analysis of 65 carbonate samples,the characteristics of early Cambrian Canglangpu palaeo-ocean environment in central Sichuan are discussed.After eliminating invalid data,theδ13 C V-PBD values of the early Canglangpu episode in central Sichuan range from-3.4‰to-0.4‰,with an average of-1.4‰,theδ18 O V-PBD values ranges from-10.0‰to-5.9‰,with an average of-8.2‰.Longitudinally,carbon isotope values showed a negative drift,with a trend of first increasing and then decreasing,and the variation range of the bottom and middle and upper parts was small,while the fluctuation range of the top was large.The paleo-marine environment analysis shows that the average salinity of the lower member of Canglangpu Formation in central Sichuan is 33.6‰.As a result of sea level fluctuation,the salinity of the sea water is lower in the early Canglangpu Formation and higher in the late Canglangpu Formation and the low salinity index and salinity number is likely to be resulted from the mixing of continental freshwater.Seawater temperature ranges from 11.6℃to 29.6℃,with an average of 21.3℃.The temperature of the lower member of Canglangpu Formation was relatively high in the early stage,and fluctuated frequently in the late stage,with an obvious tendency to decrease.

关 键 词：四川盆地 沧浪铺组 碳氧同位素 古海洋环境 

分 类 号：P597[天文地球—地球化学]