塔里木地区寒武纪岩相古地理及沉积演化

Lithofacies palaeogeography and sedimentary evolution of the Cambrian in Tarim area

以露头和钻井资料为基础,以地震资料为依托,以"统"为编图单元,分5个步骤完成塔里木地区寒武纪岩相古地理图的编制:①等时地层格架建立、②沉积地质学分析、③地震资料沉积地质特征解释、④地层厚度图分析和⑤综合分析。新的图件揭示了寒武纪塔里木地区的古地理格局:塔西台地位于中西部,是一个大型台地;罗西台地位于东部罗西1井区,规模要小得多;两个台地之间是塔东欠补偿盆地。这种古地理格局在寒武纪伸展构造背景下继承性发展。不同相带的碳酸盐沉积速率、相对海平面变化和古气候条件控制了碳酸盐岩台地内部沉积环境的分异,这也是中寒武纪形成大面积分布的膏盐岩沉积的主要原因。

Based on the outcrops,drilling wells and seismic data,the lithofacies palaeogeography maps of the Cambrian in Tarim area were compiled with 5 steps of ①stratigraphic framework establishment,② sedimentation geology analyses,③interpretation of sedimentary characters of seismic data,④analyses of stratigraphic thickness maps and ⑤comprehensive analyses.These new maps show the distribution of the palaeogeographic units in each stage of the Cambrian：Taxi Platform,a large-scale platform,located in the central and western parts of the Tarim area,while Luoxi Platform,more smaller than the former one,located in the eastern part of the Tarim area.Between the 2 platforms,there was a starved basin which was named Tadong Basin.In the Cambrian,these palaeogeographic units had developed inheritively under the sustained stretching tectonic setting.The deposition rate,palaeoclimate and relative changes of sea level controlled the differentiation of sedimentary environments in carbonate platform,and also caused the formation of widespread gypsum and salt rock in the Middle Cambrian.