乌什城南剖面沉积相类型及特征

Types and Characteristics of Sedimentary Facies in the Southern Section of Wushi

摘要: 乌什凹陷是塔里木盆地西北缘重要的勘探区域目标之一。针对塔里木盆地乌什凹陷沉积特征差异较大的问题，文章通过研究乌什凹陷石炭系沉积相类型及特征，通过野外露头剖面观察、薄片鉴定等方法，综合研究了乌什城南地区石炭系海相和海陆过渡相地层的沉积相类型和特征，分析了石炭系的沉积，揭示了沉积相类型及特征。乌什城南剖面早石炭世时期蒙达勒克组主要为扇三角洲沉积；早石炭世晚期，乌什组底部发育潮坪相沉积，中上部为五套泻湖相夹辫状河三角洲相沉积，库鲁组发育扇三角洲相沉积；晚石炭世早期索格当他乌组自下而上发育滨岸–陆堋–扇三角洲相沉积。暗色泥岩和滩坝砂体、辫状河三角洲砂体在纵向上往往构成了良好的生储盖组合，表明乌什西地区石炭系具有良好的油气潜力。

Abstract: Wushi sag is one of the important exploration targets in the northwest margin of the Tarim Basin. In view of the large differences in sedimentary characteristics in Wushi Depression, Tarim Basin, this paper comprehensively studies the sedimentary facies types and characteristics of the Carboniferous Marine facies and Marine and continental transition strata in the southern section of Wushi by means of field outcrop profile observation and thin section identification, analyzes the deposition of Carboniferous, and reveals the types and characteristics of sedimentary facies. The early Carboniferous Mondalek Formation in the southern section of Wushi is mainly a fan delta deposit. In the late Early Carboniferous period, the bottom of the Wushi Formation developed tidal flat facies, the middle and upper part of the Wushi Formation developed braided river delta facies, and the Kulu Formation developed fan delta facies. Shore-continental p-fan delta facies deposits developed from bottom to bottom in the early Late Carboniferous Sogedangtawu Formation. Dark mudstone, beach bar sand body and braided river delta sand body often form a good combination of source reservoir and cover in the longitudinal direction, indicating that the carboniferous system has good oil and gas potential in the Wushi area.