Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education,China University of Geosciences(Wuhan),Wuhan　 430074,China

以三塘湖盆地条湖凹陷为研究对象，围绕西山窑组地层的层序地层细分与聚煤规律研究这一关键问题，充分运用含煤岩系层序地层学等理论方法，探讨三塘湖盆地条湖凹陷内西山窑组含煤岩系地层聚煤规律。综合三塘湖盆地条湖凹陷内的钻井、测井和地震等资料，运用层序地层学方法进行高精度地层划分对比，将其划分为3个三级层序(SQ1，SQ2，SQ3)，根据地层叠置样式及岩相变化特征进一步在三级层序内部识别出低位体系域(LST)、湖扩体系域(EST)以及高位体系域(HST);在构建的层序格架内部分析其古地理发育特征和演化过程，识别出辫状河、辫状河三角洲及湖泊等沉积相类型;盆缘到盆中心之间的滨浅湖-三角洲平原环境过渡区域是泥炭发育的最佳场所，其中在三角洲前缘及三角洲平原的接触界面处有范围性的厚层煤发育;可容纳空间变化速率与泥炭堆积速率之间的平衡对煤层形成具有重要控制作用，湖扩体系域的早期和晚期成煤厚度大范围广，而高位体系域时期则相对较薄连续性差;在此基础上，建立了条湖凹陷西山窑组的聚煤模式，聚煤中心主要发育于湖扩体系域早期和晚期的湖泊和三角洲过渡部分。系统开展本次研究不但能够进一步了解西山窑期凹陷及全盆的古地理环境，还对该地区煤炭资源评价和勘探开发提供借鉴。

Taking Tiaohu sag of Santanghu Basin as the research subject,this paper focuses on key problems of se- quence stratigraphy subdivision and coal accumulation. Meanwhile it makes full use of the theoretical methods such as sequence stratigraphy of coal-bearing strata to discuss the coal accumulation of the Xishanyao formation. Detailed stra- tigraphic analyses of data from boreholes for the Xishanyao formation have been conducted in Tiaohu sag of Santanghu Basin and it is divided into three third-order sequences. Lowstand systems tract (LST),lake transgressive systems tract (EST),highstand systems tract (HST) are subdivided by the stacking patterns of stra-tigraphy,changes in lithology and lithofacies. A series of sequence-specific paleogeographic maps have been con-structed based on the contours of li- thological parameters. The paleogeographic units include braided river,braided river delta and lacustrine sedimentary system facies. The preferred sites of coal accumulation is the transition region between braided river delta and lacus- trine from the margin to the center. Furthermore,there are a range of thick coal seams at the contact interface between the delta front and the delta plains. The coal-accumulation features in sequence stratigraphic framework are clarified. Through analyzing coal seam change features,coal-rich zone,the accommodation rate in relation to peat production would have controlled on coal formation and preservation. During initial and late lake transgressive systems tract depo- sition,coal seams are thick and continuous while only thin,discontinuous and scattered coal seams are formed in the highstand system tract. The comprehensive coal-accumulation model is established based on the researches mentioned and the major coal seams are accumu-lated in the transition of the lake to the delta of the early and late EST. The re- sults will not only provide a se-quence stratigraphical model and paleoenvironmental framework for understand of the whole Santanghu Basin for this interval,but also are of practical significance for after coal resources exploration in San- tanghu Basin.

ZHANG Liwei,YAN Detian, LIU Wenhui, et al. Sequence strata and coal accumulation of Xishanyao Formation in Tiaohu sag of Santanghu Basin,Sinkiang[J]. Journal of China Coal Society,2019,44(2):545-556.