Based on field outcrop observations in the north Tarim Basin and thin-section observations of typical drilling wells, we accurately established a sedimentary model and finely characterized the spatiotemporal distribution patterns of high-energy mound and shoal facies. The results show that a carbonate ramp is developed in Xiaoerbulake Formation in Tarim Basin. The types of sedimentary facies include mixed tidal flat, inner-ramp (dolomite-flat, lagoon and shoal), middle-ramp (inner zone, outer zone, microbial mounds, and shoal) and outer ramp-basins. By characterizing the spatiotemporal distribution of sedimentary facies within the isochronous stratigraphic framework, an internal depression and distally steepening carbonate ramp model was established. The high-energy mound and shoal facies deposits with high-quality reservoirs are mainly affected by the original paleogeomorphy and fluctuation of relative sea level. The middle-ramp shoals are developed in Tazhong area, the middle-ramp mounds and shoals are developed in Bachu area and Keping area, and the middle-ramp shoals are developed in the high paleogeomorphy of Lunnan area.

Tarim Basin, Lower Cambrian, Xiaoerbulake Formation, sequence stratigraphic framework, sedimentary facies, sedimentary model

依据塔里木盆地北部野外露头和典型钻井样品的薄片观察, 准确地建立肖尔布拉克组沉积模式, 精细地刻画高能丘滩相的时空分布规律。结合前人研究成果, 经过综合分析认为, 塔里木盆地下寒武统肖尔布拉克组具有碳酸盐岩缓坡沉积的特征, 发育混积潮坪、内缓坡(云坪、潟湖与浅滩)、中缓坡(内带、外带、洼地、微生物丘和浅滩)、外缓坡–盆地等沉积相和岩相类型。通过精细地刻画等时层序地层格架内不同地区沉积相的时空展布特征, 建立“盆地中部低洼、东部远端变陡”的碳酸盐岩缓坡沉积模式, 有利于优质储层发育的高能微生物丘和浅滩主要受原始古地貌和相对海平面升降影响, 塔中地区发育内缓坡浅滩, 巴楚地区和柯坪地区发育中缓坡微生物丘或浅滩, 轮南地区高部位发育中缓坡浅滩。