Provenance Analysis of 3rd Member of Oligocene Lingshui Formation in the Yacheng 13-1 Gasfield, Qiongdongnan Basin

Abstract：Provenance system analysis is one of the key means for determining the genetic type, spatial distribution and evolution of the reservoir. In this paper, Based on an integrated analysis of palaeogeomorphology, heavy minerals, composition and structure of debris and dip log data, the authors systematically studied the provenance of 3rd Member of Oligocene Lingshui Formation in Yacheng 13-1 Gasfield within Qiongdongnan Basin and revealed that the provenance system of the study area was derived from the northwest during the deposition of 3rd Member of Lingshui Formation. The clastic sediments are mainly lithic feldspathic quartzite and feldspathic quartzite with high content of quartz. An analysis of heavy mineral assemblages shows that the rock types of the source area were mainly acidic magmatic rocks, metamorphic rocks and reworked sedimentary rocks. Because of the moderate distance from the source area to the study area and the existence of some slopes between them, the source area was likely to produce large debris by mechanical crushing and this type of mother rock might have been the inherent factor responsible for the formation of braided channel delta sandstone and sedimentary characteristics in 3rd Member of Lingshui Formation in the study area.