摘要
基于岩心、岩石薄片观察,结合X射线荧光分析、微区原位主微量和稀土元素、碳氧锶同位素组成、流体包裹体等测试分析及盆地模拟,对准噶尔盆地玛湖凹陷东斜坡石炭系玄武岩方解石脉特征及成因进行研究。结果表明研究区脉体发育3期方解石充填:第Ⅰ期贫锰,稀土元素配分曲线平坦,强负铈异常,弱—中等负铕异常,碳同位素组成偏轻,表明其形成受到大气淡水影响;第Ⅱ期富锰和轻稀土,具有弱正铈异常和轻微正铕异常,碳同位素组成相对较重而锶同位素比值较低,表明深部成岩流体对其形成有一定影响;第Ⅲ期富铁和锰,稀土元素配分曲线与第Ⅱ期相似但铈异常和铕异常波动较大。第Ⅰ、Ⅱ期形成于距今约250~260 Ma的浅埋藏环境,对应于二叠纪末期晚海西运动;第Ⅲ期很可能形成于晚三叠世印支运动。研究认为不整合面附近玄武岩裂缝中的方解石沉淀主要与大气淡水淋滤上覆下二叠统风城组碳酸盐矿物有关,较早地破坏了石炭系风化壳储集层,但是在充填程度较弱或后期溶蚀作用较强的位置仍可发育相对优质储集层,如风城组缺失的构造高部位、垂向上距离风城组较远的位置以及靠近湖盆内部的古潜山等地区。图16表1参40。
The characteristics and genesis of the calcite veins in Carboniferous basalt in the east slope of Mahu Sag,Junggar Basin are investigated based on observation of cores and thin sections;analyses of X-ray fluorescence,in situ major,trace and rare earth elements(REE),carbon,oxygen and strontium isotopes,fluid inclusions,as well as basin modeling.There are three stages of calcite fillings.The stage Ⅰ calcite is characterized by low Mn content,flat REE pattern,strong negative Ce anomaly,weak to moderate negative Eu anomaly,and light carbon isotopic composition,indicating the formation of the calcite was affected by meteoric water.The stage Ⅱ calcite shows higher Mn and light REE contents,weak positive Ce anomaly and slight positive Eu anomaly,and a little heavier carbon isotopic composition and slightly lower strontium isotope ratio than the stage Ⅰ calcite,suggesting that deep diagenetic fluids affected the formation of the stage Ⅱ calcite to some extent.The stage Ⅲ calcite is rich in iron and manganese and has REE pattern similar to that of the stage Ⅱ calcite,but the cerium and europium enomalies vary significantly.The stage Ⅰ and Ⅱ calcites were formed in shallow diagenetic environment at approximately 250–260 Ma,corresponding to Late Hercynian orogeny at Late Permian.The stage Ⅲ calcite was probably formed in the Indo-China movement during Late Triassic.It is believed that the precipitation of calcite in basalt fractures near unconformity was related to leaching and dissolution of carbonates in the overlying Lower Permian Fengcheng Formation by meteoric water,which destructed the Carboniferous weathering crust reservoirs in early stage.Relatively high quality reservoirs could be developed in positions with weak filling and strong late dissolution,such as structural high parts with Fengcheng Formation missing,distant strata from Fengcheng Formation vertically,buried hills inside lake basin,etc.
作者
夏鲁
操应长
卞保力
刘海磊
王晓雪
赵一伟
燕苗苗
XIA Lu;CAO Yingchang;BIAN Baoli;LIU Hailei;WANG Xiaoxue;ZHAO Yiwei;YAN Miaomiao(Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,China;Research Institute of Petroleum Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay 834000,China;Research Institute of Petroleum Exploration and Development,PetroChina Tarim Oilfield Company,Korla 841000,China)
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2021年第4期745-755,共11页
Petroleum Exploration and Development
基金
国家自然科学基金委油气成藏机理创新研究群体(41821002)
中国石油天然气股份有限公司重大科技专项《准噶尔盆地油藏富集规律及勘探技术研究与应用》(2017E-0401)
博士后科学基金面上项目(2019M662465)。
作者简介
第一作者:夏鲁(1985-),男,山东滕州人,博士,中国石油大学(华东)地球科学与技术学院在站博士后,主要从事致密砂岩油气藏及储集层地质学研究。地址:山东省青岛市黄岛区长江西路66号,中国石油大学工科楼C座,邮政编码:266580。E-mail:xialu999@126.com;联系作者:操应长(1969-),男,安徽潜山人,博士,中国石油大学(华东)地球科学与技术学院教授,主要从事沉积学与油气储集层地质学方面的教学和科研工作。地址:山东省青岛市黄岛区长江西路66号,中国石油大学地球科学与技术学院,邮政编码:266580。E-mail:caoych@upc.edu.cn。
