新疆莎车盆地早古新世沉积环境演化初探

新疆莎车盆地古新世断续海侵环境下发育阿尔塔什组巨厚的石膏岩，古新世早期盐湖沉积范围位于西昆仑及南天山山前，伴随着后期海侵范围的进一步扩大，盐湖沉积范围覆盖整个莎车盆地。论文通过对西昆仑及南天山山前5口石油钻井剖面中阿尔塔什组含盐系地层开展钻孔岩屑地球化学分析，认为古新世早期盐湖中钾、钠、钙、镁、硫酸根变化趋势基本符合盐湖蒸发浓缩趋势。盐湖受海水断续注入的影响，古新世早期至少经历了2次浓缩期和1次浓缩趋势，及至少3期卤水淡化，暗示阿尔塔什组发育早期盐湖至少经历了3次不同时期的海侵过程。西昆仑及南天山山前2个含盐系剖面露头中石膏硫同位素确定古新世早期莎车盆地经历了从海相至海陆交互相蒸发岩沉积环境的转变。其中西昆仑山前中段的阿尔塔什地区为海相蒸发岩沉积环境，该时期盐湖经历了3次海侵，与钻井岩屑地球化学分析结果相一致；莎车盆地西北部的大山口地区，经历了海陆交互相 海相 海陆交互相 海相的沉积环境转变，该区海陆交互相含盐系地层发育可能受南天山山前较高古地势控制或山区淡水补给盐湖的影响，而西昆仑山前中段的海相蒸发岩环境，反映出莎车前陆盆地阿尔塔什地区古地势低于大山口地区，造成沉积环境差异。

Preliminary study on evolution of sedimentary environment in Early Paleocene in the Yarkand basin, Xinjiang

?Large-thickness gypsum of Aertashen Formation is developed in intermittent marine transgressive environment in the Yarkand Basin in Paleocene, Xinjiang. The sedimentary range of saline lake is located in the West Kunlun and south Tianshan piedmonts in the early Paleocene, and gradually expanded to the whole basin accompanied large-scale transgression in later period. The cuttings, from 5 drilling holes'' evaporite profiles located in the west kunlun and south tianshan piedmonts, are analyzed by geochemical method to reveal that the evolution process of saline lake in potassium, magnesium, sodium, calcium and sulfate radical changing trend in line with evaporation and concentration trend of saline lake the early Paleocene. The saline lake, affected by intermittent transgression environment, undergoes at least 2 concentrated stages and 1 enrichment trend of potassium in the early Paleocene, and the intervals of concentrated stages represent at least 3 times in different transgressive phases. Sulfur isotopes analysis on gypsum from outcrops in West kunlun and south Tianshan piedmonts reveal that from the marine to terrestrial sedimentary environment in Yarkand Basin in the early Paleocene. The Aertashen area, located in middle of west kunlun piedmont, is a marine sedimentary environment, which reflects the saline lake has experienced 3 times expanded marine transgression, and be consistent with drilling cuttings geochemical analysis results. The Dashan area in the northwest region of Yarkand Basin has experienced changes on paralic - marine - paralic - marine environment, may be affected by ancient terrain or fresh water supplies, but the Aertashen area, in the middle part of West kunlun piedmont, is marine evaporative sedimentary environment. This reflects lower ancient terrain than Dashankou area controlled by tectonic background of the foreland basin, resulting in differences in sedimentary environment.