塔西北下寒武统风暴活动特征及其沉积学响应

在塔西北阿克苏露头区发育多套类型不同的下寒武统肖尔布拉克组风暴岩,它们宏观上与微生物丘混生或共生,微观上可见不同类型的微生物结构,但与此相关的研究甚少。以露头观察和室内鉴定为基础,在苏盖特布拉克地区和昆盖阔坦地区划分出4类8种各具特色的微生物丘—风暴岩沉积序列,并归纳总结了塔西北地区下寒武统肖尔布拉克组风暴沉积模式,认为其发育位置和沉积特征主要受控于“三面”,包括平均海平面(MSL)、正常浪基面(FWB)和风暴浪基面(SWB);“四期”,包括平静期、高峰期、衰减期与停息期;“五流态”,包括风暴涡流、风暴下部回流(包括风暴碎屑流和风暴浊流)沉积与风暴上部回流(包括风暴漫流和风暴潮流)。另外古风暴中心的发育位置也可影响风暴沉积特征。最后在前人研究的基础上,对“贫乏骨骼的风暴海”的形成条件进行探讨。

Storm Activity Characteristics and Their Sedimentary Responses for the Xiaoerbulak Formation,Lower Cambrian,NW Tarim Basin

Several different types of tempestites are found in the Xiaoerbulak Formation, Aksu area, Tarim Basin. Tempestites and bioherms have a symbiotic relationship or macroscopic mix growth pattern, with various types of microbial composition in microcosmic aspects. However, little research has performed on this phenomenon. Based on outcrop section observations and thin section identifications, 4 classes and 8 types of bioherm-tempestite sedimentary successions are recognized in the Sugaitblak and Yutixi areas, and the sedimentary model is established. As a result, corresponding locations and characteristics are mainly controlled by "three bases", including mean sea level, fair wave base, and storm wave base, "four stages", including quiet stage, strong stage, weakening stage, and dying-out stage, and "five flow regime", including storm eddy, lower storm back-flow (split into storm turbidity currents and storm debris flow), and upper storm back-flow (split into storm overflow and storm tide). The position of the ancient storm center can also affect the storm deposit characteristics. At last, based on previous research, the origin of the stormy sea with the scarcity of metazoan skeletons is discussed.