四川盆地川中地区须家河组沉积和成岩环境分析  

Xujiahe Formation in Central Sichuan Area

作　　者：肖迪 蔡娉婷 XIAO Di;CAI Pingting(College of Earth Sciences,East China Institute of Technology,330013,Nanchang,PRC)

机构地区：[1]东华理工大学地球科学学院,南昌330013

出　　处：《江西科学》2023年第2期254-260,共7页Jiangxi Science

基　　金：国家自然科学青年基金项目(41402085);环境重点实验室开放基金项目(NRE1403)。

摘　　要：以四川盆地川中须家河组为研究对象,通过扫描电镜、X-衍射、碳氧同位素和流体包裹体分析,对须家河组砂岩沉积和成岩环境进行研究。结果表明:须家河组砂岩以方解石为主要碳酸盐胶结物,含少量白云石。碳氧同位素均为负值:δ^(13)C值分布于-8.1‰~-0.8‰;δ^(18)O值分布于-17.6‰~-10.3‰。古盐度Z值分布范围为101.0~120.5。碳氧同位素值计算古温度为72℃~124℃,平均值101℃;流体包裹体均一温度范围为60~140℃,与碳氧同位素计算的古温度基本吻合。较高的古地温可促进致密化,提高生烃能力。须家河组砂岩为陆相沉积,随着沉积作用的进行,沉积初期到中期水体呈具咸化趋势,晚期盐度明显下降。古盐度的变化反映须家河组砂岩沉积初—中期气候较干旱,晚期气候较温湿。Taking the Xujiahe Formation in central Sichuan Basin as the research object,the sedimentary and diagenetic environment of the Xujiahe Formation sandstone was studied by scanning electron microscopy,X-ray diffraction,carbon and oxygen isotope and fluid inclusion analysis.The results show that the carbonate cement of the Xujiahe Formation sandstone is mainly calcite,with a small amount of dolomite.Both carbon and oxygen isotopes are negative:Theδ^(13)C value is distributed between-8.1‰and-0.8‰;Theδ^(18)O value is distributed between-17.6‰and-10.3‰.The distribution range of paleosalinity Z value is 101.0~120.5.The calculated paleotemperature of carbon and oxygen isotope values is 72℃~124℃,with an average of 101℃;The homogenization temperature of fluid inclusions ranges from 60℃to 140℃,which is basically consistent with the paleotemperature calculated by carbon and oxygen isotopes.Higher paleotemperature can promote densification and improve hydrocarbon generation capacity.The sedimentary environment of Xujiahe Formation sandstone is continental sedimentation.With the progress of sedimentation,the water body has a salty tendency from the initial to the middle of sedimentation,and the salinity in the late period decreases significantly.The change of paleosalinity reflects that the climate of Xujiahe Formation sandstones was dry in the early to middle stages of sedimentation,and warm and wet in the late stages.

关 键 词：碳酸盐胶结物 碳氧同位素 须家河组 成岩作用 沉积环境 

分 类 号：P588.2[天文地球—岩石学]