Abstract:

The regions of huge amount of hydrocarbon mainly develop in passive continental margin, active continental margin and continental rifts in the global，while the northern margin of the Jiangnan-Xuefeng uplif has the different tectonic settings of the slopes about intracontinental depression and paleo-uplift margin. We explore the major factors and destruction mechanisms of marine hydrocarbon enrichment of the study area, and compare to the main reasons about the development of hydrocarbon enrichment zones (regions) all over the world, and try to build the related patterns of marine hydrocarbon enrichment and destruction. We attempt to explain a new marine enrichment unit in intercontinent block, which is a superimposed slope zone of intracontinental depression and paleo-uplift margin and similar to the northern margin of the Jiangnan-Xuefeng uplift. We suggest two main controlling factors for the massive accumulation. One is two sets of high-quality hydrocarbon source rocks of the Lower Cambrian and Lower Silurian. The other is two stages of favorable space-time matching relation for accumulation on the middle-late Caledonian cycle and the early of Late Indosinian-Early Yanshannian cyle. During the two key destruction stages of the late Caledonian cycle and the late of the Late Indosinian-Early Yanshannian cycle, marine accumulation were destroyed by uplifting and denudation, fault opening and magmatic activity. Our results suggests the spactial-temperal matching superimposed slope zone is a favorable accumulation area, but also an active transformation area for hydrocarbon.

Key words: Jiangnan-Xuefeng uplift, Yangtze block, marine strata, hydrocarbon accumulation, superimposed slope zone