准噶尔盆地玛湖凹陷二叠系风城组碱湖沉积特征与古环境演化  

Alkaline-lacustrine deposition and Paleoenvironmental evolution in Permian Fengcheng Formation at the Mahu Sag, Junggar Basin, NW China

作　　者：张志杰[1] 袁选俊[1] 汪梦诗 周川闽[1] 唐勇[2] 陈星渝 林敏捷 成大伟 ZHANG Zhijie;YUAN Xuanjun;WANG Mengshi;ZHOU Chuanmin;TANG Yong;CHEN Xingyu;LIN Minjie;CHENG Dawei(Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;Petrochina Xinjiang Oilfield Company,Karamay 834000,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油新疆油田公司,新疆克拉玛依834000 [3]北京大学地球与空间科学学院,北京100871

出　　处：《石油勘探与开发》2018年第6期972-984,共13页Petroleum Exploration and Development

基　　金：国家油气重大专项"岩性地层油气藏成藏规律;关键技术及目标评价"(2017ZX05001);中国石油天然气股份有限公司科技项目"多类型湖盆沉积体系分布与岩相古地理分析"(2016B-0302)

摘　　要：基于岩心及薄片观察、地球化学及元素分析、测井电性响应特征、岩相类型及展布等研究,揭示准噶尔盆地玛湖凹陷下二叠统风城组的碱湖沉积特征及其演化模式。结果表明,风城组主要发育6种岩相类型,其中含碱性矿物岩相主要发育在风二段,富有机质泥岩岩相广泛分布于风一段上部和风三段下部,常与白云岩及云质岩类岩相呈互层产出。风城组古环境演化主要受火山活动和古气候控制,可以划分为5个阶段。第1阶段(风城组一段沉积前期)火山活动强烈,气候较干旱,火山碎屑岩-沉火山碎屑岩发育;第2阶段(风城组一段沉积后期)火山活动减弱,气候较湿润,富有机质泥岩发育,形成风城组主要烃源岩;第3阶段(风城组二段沉积早期)气候转向干热、湖盆开始萎缩,盐度逐渐升高,白云岩及云质岩类发育;第4阶段(风城组二段沉积后期)气候持续干热、湖平面低、盐度高,天然碱等特殊碱性矿物析出,标志着碱湖的最终形成;第5阶段(风城组三段沉积期)气候再次转为湿润,湖平面升高,湖盆开始淡化,以陆源碎屑岩、云质岩类沉积为主。Alkaline-lacustrine deposition and its evolution model in Permian Fengcheng Formation at the Mahu Sag,Junggar Basin were investigated through core and thin-section observation,geochemical and elemental analysis,logging response and lithofacies identification.Six lithofacies are developed in the Fengcheng Formation.The Feng 2 Member(P1f2)is dominated by lithofacies with alkaline minerals,while the upper part of the Feng 1 Member(P1f1)and the lower part of the Feng 3 Member(P1f3)are primarily organic-rich mudstones that are interbedded with dolomite and dolomitic rock.Paleoenvironment evolution of Fengcheng Formation can be divided into 5 stages,which was controlled by volcanic activity and paleoclimate.The first stage(the early phase of P1f1)was characterized by intensive volcanic activity and arid climate,developing pyroclastics and sedimentary volcaniclastic rocks.The secondary stage(the later phase of P1f1)had weak volcanic activity and humid climate that contributed to the development of organic-rich mudstone,forming primary source rock in the Fengcheng Formation.The increasing arid climate at the third stage(the early phase of P1f2)resulted in shrinking of lake basin and increasing of salinity,giving rise to dolomite and dolomitic rocks.The continuous aird climate,low lake level and high salinity at the fourth stage(the later phase of P1f2)generated special alkaline minerals,e.g.,trona,indicating the formation of alkaline-lacustrine.The humid climate made lake level rise and desalted lake water,therefore,the fifth stage(P1f3)dominated by the deposition of terrigenous clastic rocks and dolomitic rocks.

关 键 词：准噶尔盆地 二叠系风城组 沉积特征 古环境恢复 碱湖沉积 岩相 玛湖凹陷 

分 类 号：TE122[石油与天然气工程—油气勘探]