Paleo-environment of the Late Triassic-Early Jurassic in the land area next to the southern East China Sea Shelf

The research area, the land next to the southern East China Sea Shelf Basin, includes both the southeastern part of Fujian Province and the northeastern part of Guangdong Province. Based on field geological survey, microscopic observation and geochemical testing, the paleo-environment of the Late Triassic-Early Jurassic deposits of the area is carefully investigated. It is revealed that the sediments are deposited in a deep water anaerobic environment during late Triassic-Early Jurassic, when the region was dominated by warm and humid climate in the southeastern part of Guangdong Province. During Late Triassic, the southern part of the land area gradually became shallower northwards. Consequently, the southern part of the study area was dominated by a assemblage of coast, shallow shelf and deep shelf, while the northern part dominated by a marine-land transitional environment under the affect of transgression. In early Jurassic, the southern part of the region became an outer shelf with great water depth, and the northern part become marine-continental transitional and sometimes continental environment alone. Based on the paleo-environment research of the adjacent land area with the same geotectonic background, it is concluded that the Mesozoic paleo-environment varied southwards from continent to marine in the southern part of the East China Sea Shelf Basin. The paleo-geographic pattern is helpful to study the Mesozoic petroleum geology in the region.