The distribution of the Lower Cambrian source rocks in the Tarim Basin has long been an exploration problem in oil and gas exploration of the Tarim Basin.Based on the analysis of the regional tectonic settings,stratigraphic correlation,structural interpretation and restoration of the ancient tectonic were studied using the outcrops,new drillings and seismic data.And the Neoproterozoic prototype basins,the palaeotectonic and the tectonic-sedimentary environment were discussed to restrain the distribution of the Lower Cambrian source rocks in the Tarim basin.The study shows that the Keping and Yecheng regions in the western margin of the Tarim basin experienced an evolution series of basin from intra-continental faulting to initial passive continental margin during Neoproterozoic,while the Kuruktag area in the northeastern Tarim basin is characterized by rift and post-rift depression.The seismic reflection features further reveal that the similar basin-forming occurred in the Tarim basin.The Nanhua faulting is characterized obviously by the horst and graben while the depression stage was dominated by a uniform subsidence since the Sinian period.The Keping movement in late Sinian resulted in uplifting of the Tarim basin,and this laid the foundation for the formation of structural paleogeomorphology of the Tarim Basin before Cambrian deposition.Therefore,the Tarim basin is generally characterized by "high in west and south,and low in east and north",which controls the formation and distribution of hydrocarbon source rocks in lower Cambrian.The large-scale thickening of the middle to lower Cambrian in the terrace of western Tarim is likely related to inherited subsidence,which provided a favorable sedimentary environment for development of carbonatic continental shelf hydrocarbon of the Yurtusi Formation.Deep water continental shelf-basin facies muddy source rocks of the Xishanbrake to Xidashan formations not only deposited in the Manjiaer depression but also occur in the Awat depression.Although most areas in the central uplift belt are unfavorable for formation of high quality source rocks,it can not be ruled out that the lower Cambrian lagoonal-facies source rocks occur locally in this area.Different from the high carbonatic source rocks in the north of the Tarim basin,deep-water muddy hydrocarbon source rocks with high content of clastic rocks was developed in a tectonic-sedimentary environment characterized by the reformed boundary in the southern margin of the Tarim basin.%下寒武统优质烃源岩的分布一直是塔里木盆地油气勘探的难点问题.在区域构造演化背景分析基础上,利用露头和新的钻井、地震资料,通过地层对比、构造解释和古地貌恢复,探讨了塔里木新元古代盆地原型、古构造及下寒武统烃源岩发育的构造背景.研究认为塔里木盆地西缘的柯坪和叶城地区,新元古代经历了陆内断陷到初始被动大陆边缘的盆地演化序列,而在塔东北的库鲁克塔格地区,主要以裂谷及其衰退期的拗陷为特征.地震反射特征进一步显示在塔里木陆内也具有相似的成盆作用,南华纪断陷具有清楚的垒、堑结构,震旦纪以后以拗陷阶段的均衡沉降为主.发生在晚震旦世末的柯坪运动造成全区抬升,奠定了塔里木盆地寒武系沉积前的构造古地貌,总体表现为西高东低,南高北低,控制了下寒武统烃源岩的形成、分布.塔西台地内中—下寒武统出现大面积增厚,可能与晚震旦世以后继承性的沉降作用有关,形成有利于玉尔吐斯组类型的碳酸盐质陆棚相烃源发育的沉积环境.而西山布拉克—西大山组类型的深水陆棚—盆地相的泥质烃源岩不仅在满加尔坳陷内发育,还可能在阿瓦提坳陷内分布.尽管中央隆起带大部分地区不利于优质烃源岩发育,但不能排除局部地区仍可能存在下寒武统泻湖相烃源岩.与盆地北部高碳酸盐岩含量的烃源岩不同,塔里木南缘改造边界附近具有形成高碎屑岩含量的深水泥质烃源岩的构造—沉积环境.
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