摘要
本文选取官地矿太原组8煤层顶板灰岩及方解石脉为研究对象,开展了稀土元素和碳、氧、锶同位素以及流体包裹体分析测试,并探讨方解石脉成因和地质意义。结果表明,方解石脉有两种类型,两类脉中的方解石的矿物学特征无明显差别,第一类脉中方解石富集轻稀土,第二类富集中稀土;二者的C、O同位素组成与灰岩一致。富集中稀土的方解石的^(86)Sr/^(87)Sr值(0.7101)略高于富集轻稀土方解石(0.7093),且含有高成熟度液态烃包裹体,因此可认为富Sr和含烃类流体与灰岩发生水-岩反应,灰岩溶解和CO_(2)去气作用共同导致方解石脉形成;二者的盐水包裹体的盐度为16%~22%NaCl_(cqv),表现出高盐度特征;包裹体均一温度为70~80、100~110和130~140℃。结合地层埋藏史,可以认为太原组地层在三叠纪有3阶段油气充注:早-中三叠世,低成熟度液态烃形成并早期注入;中三叠世,有机质进入成熟阶段,开始生烃、排烃,局部成藏;晚三叠世,有机质进入高成熟阶段,该时期是煤成烃的主要成藏期。
In this paper, the calcite veins and limestones in roof of the 8coal bed in the Taiyuan Formation of the Guandi coal mine have been selected as the research objects for analyzing carbon, oxygen, and strontium isotopes, contents of rare earth elements, and microthermometric data of fluid inclusions of the calcite veins in order to discuss the genesis and geological significances of those calcite veins. The results show that there are two types of calcite veins with no obviously mineralogical difference.The first type of calcite veins is enriched in LREE, but the second type of calcite veins is enriched in MREE. The C and O isotopic compositions of these two types of calcite veins are generally consistent with those of limestones. The average^(86)Sr/^(87)Sr value of the MREE-enriched calcite veins(0.7101) is slightly higher than that of the LREE-enriched calcite veins(0.7093). In addition, the MREE-enriched calcite veins contain high-maturity liquid hydrocarbon inclusions. Therefore, it is believed that the calcite veins were formed by the dissolution and CO_(2)degassing of limestone resulted from the water-rock interaction of the Sr-rich and hydrocarbon-bearing fluids and limestone. The salinities of saline aqueous inclusions mainly range from 16% to 22% NaCl_(cqv), showing high salinity characteristics for inclusion fluids. The homogenization temperatures of fluid inclusions vary from 70 to 80 ℃, from 100 to 110 ℃, and from 130 to 140 ℃. Combined with the burial history of the stratum, it can be considered that three stages of oil and gas charging had occurred in the Taiyuan Formation in the Triassic. In the Early-Middle Triassic, the low-maturity liquid hydrocarbons were formed and injected into the Taiyuan Formation. In the Middle Triassic, the generation, expulsion, local accumulation of hydrocarbons occurred because organic matters were evolved to the mature stage. In the Late Triassic, the main accumulation of hydrocarbons occurred because organic matters were evolved to the high maturity stage. The La
作者
王位
高键
孙蓓蕾
刘超
曾凡桂
WANG Wei;GAO Jian;SUN Bei-lei;LIU Chao;ZENG Fan-gui(Department of Earth Science&Engineering,Taiyuan University of Technology,Tai-yuan 030024,China;Key Lab.of Geology of Coal and Coal Measure Gas,Shanxi Province,Taiyuan 030024,China;SINOPEC Petroleum Exploration and Production Research Institute,Beijing 100083,China)
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2022年第3期645-656,共12页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
国家自然科学基金资助项目(41872177,42002137)
山西省科技重大专项课题(20191102001)。
