塔西南坳陷古新世初期广泛发育厚层蒸发岩沉积。阿尔塔什组蒸发岩为断续海侵环境下的产物，依据海侵范围扩大时蒸发岩系地层中出现的多套泥岩、泥灰岩沉积为标志，选取了坳陷内8口钻孔剖面进行沉积韵律划分及沉积旋回的识别和对比，在古新世阿尔塔什组沉积期共识别出4期次级蒸发岩沉积旋回，每个旋回基本呈现蒸发岩－泥灰岩的岩性变化，这种沉积韵律的交替转变可能与4次小规模的海侵－海退事件密切相关。钻孔剖面对比结果显出，次级沉积旋回在各钻孔中的发育情况有所不同：研究区西部钻孔多发育完整的4期沉积旋回，至 Ks101井附近识别出3期，麦盖提斜坡只圈定出Ⅱ3、Ⅱ4期旋回，普遍缺失了前两期沉积旋回。在沉积旋回发育状况及厚度方面同样显示出东西向差异。研究表明，坳陷内蒸发岩沉积分布具有自西向东拓展的趋势，其沉积中心逐渐由西昆仑山前的 Wx1、Wb1井一带迁移至坳陷东部麦盖提斜坡的 Tc2井附近。前陆盆地基底形态和海侵－海退旋回的综合作用是造成这种变化的主要原因。最后，结合各钻孔位置及蒸发岩分布迁移特征，指出阿尔塔什期海侵过程具有阶段性，海域分布范围自西昆仑山前向东南逐渐扩展，最终遍及整个塔西南坳陷。%Evaporites with a large thickness were formed widely in the southwestern Tarim Depression during early Paleocene period.The evaporites of the Aertashi Formation were the products of intermittent transgression environment.In this study,8 drilling holes were chosen to identify and compare sedimentary cycles of evaporites.Four secondary cycles of evaporites were found.The rhythms characteristics of every cycle vary alternatively from evaporites to marl rock and this change of sedimentary rhythm was closely related with four minor transgressive-regressive events.The comparative results of the drilling holes are:The developmental condition of secondary sedimentary cycles of each drilling holes was different.4 secondary cycles of evaporites were developed completely in the western basin,and it reduced to 3 stages in the region of Ks101 drilling hole.In the Markit Slope Belt,only two stages were be delineated,missing the first two stages of secondary sedimentary cycles.The same obvious differentiation embodies in the sedimentary cycles growth degree and the thickness of sedimentary.Analysis result shows that,with the eastern expansion trend of the evaporites sediments,the depocenter moved gradually from Wx1、Wb1 drilling holes in front of Xikunlun Mountain to Tc2 drilling hole in the Markit Slope Belt.Two main controlling mechanisms may be considered for the alternation of evaporites sediments:the shape of foreland basin basement and the transgressive-regressive events.In the end,according to distribution and migration of evaporites deposition,combined with the drilling position,the phased distribution range of transgressive process occurred out in the sedimentary period of Aertashi Formation:the process of sea invasion moved from the front of Xikunlun Mountain to southeastern of the basin,and finally extended to the whole depression.
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