阜新盆地中北部新生代辉绿岩侵入特征及其对烃源岩的影响  

The intrusion characteristics of Cenozoic diabase in the middle and northern Fuxin basin and its influence on source rocks

作　　者：吴彦佳 贾建亮[1] 秦建义 王晓明 WU Yanjian;JIA Jianliang;QIN Jianyi;WANG Xiaoming(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;2107 Exploration Team,Northeast Bureau of Coal Geology,Fuxin,Liaoning 123000,China)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]东北煤田地质局107勘探队,辽宁阜新123000

出　　处：《地质学报》2022年第3期1026-1040,共15页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41772114);中央级公益性科研院所基本科研业务费专项(编号J1901-33,J1803)联合资助成果。

摘　　要：阜新盆地中北部白垩纪沉积地层中侵入岩广泛发育。该区域侵入岩岩石学特征和空间展布规律与其形成时代,以及侵入岩带来的异常高温对烃源岩生烃演化的影响仍不明确。本文通过岩石学、地球物理测井、有机地球化学、同位素年代学等方法,探讨阜新盆地中北部新生代辉绿岩侵入特征及其油气地质意义。结果表明,研究区内侵入岩主要为辉绿岩,其主要矿物为基性斜长石和辉石。辉绿岩具有典型辉绿结构,具有低自然伽马与声波时差、高电阻率与密度的测井响应特征,其产状主要为岩墙与岩床。钻井资料显示,辉绿岩侵入体具有盆地东部侵入深且规模大、西部侵入浅且规模小的特征;平面分布上与北东向的主要断裂紧密相关,呈3个北东向断续相连的分散条带。该区腰吐呼噜的辉绿岩磷灰石U-Pb同位素定年结果为33.75±1.83 Ma,指示时代为古近纪渐新世初期。此外,辉绿岩侵入带来的异常高温可以显著降低烃源岩生烃埋深,促使烃源岩成熟度大幅提高(R;最高可达2.32%),从而促进烃源岩生烃与排烃进程。一般而言,辉绿岩热效应对其上部(0.8-1.7倍)和下部围岩(0.9-1.5倍)的影响范围呈现一定的差异性。因此,阜新盆地内广泛发育的辉绿岩是古近纪始新世区域性的拉张伸展构造背景下岩浆活动的产物,其对烃源岩二次生烃具有重要的影响。Intrusive rocks are widely distributed in Cretaceous sedimentary strata of the central and northern Fuxin basin. The petrological characteristics and spatial distribution of intrusive rocks in this area and their formation age, as well as the influence of the abnormal high temperature brought by intrusive rocks on the hydrocarbon generation and evolution of source rocks are still unclear. Petrology, geophysical logging, organic geochemistry, isotope chronology methods are used in this study to explore the intrusive characteristics of Cenozoic diabase and its petroleum geological significance in the central and northern Fuxin basin. The results show that the intrusive rocks in this study area are mainly diabase, and the main minerals are basic plagioclase and pyroxene, which have typical ophitic textures. Diabase has the logging response characteristics of low gamma and acoustic time difference, high resistivity and density, and its spatial distribution forms are mainly dykes and sills. Drilling data show that the diabase intrusion has the characteristics of deep intrusion and large thickness in the east but shallow intrusion and smaller thickness in the west. The plane distribution is closely related to the main northeast-trending faults, and presents three scattered intermittently connected northeast-trending bands. Apatite U-Pb isotope dating of a diabase sample in the Yaotuhulu area of Fuxin basin, yields an age of 33.75±1.83 Ma indicating the period of the early Paleogene Oligocene. In addition, the abnormally high temperature brought about by diabase intrusion can significantly reduce the hydrocarbon generation depth of source rocks, and promote the maturity of source rocks(R;up to 2.32%), thereby promoting the hydrocarbon generation potential of source rocks and reducing their organic matter abundance. In general, the diabase have thermal aureole thicknesses on the upper surrounding sediments of 0.8-1.7 times its own intrusive thickness, and the influence range of the lower surrounding sediments is about 0

关 键 词：阜新盆地 辉绿岩 渐新世 异常高温 生烃演化 

分 类 号：P618.13[天文地球—矿床学]