Provenance and depositional facies controlling on the Upper Paleozoic excellent natural gas-reservoir in northern Ordos basin, China.

he age spectrum of detrital zircons in the He 8 and Shan 1 sandstones of the Upper Paleozoic from Ordos basin is constructed, and provenance and parent rocks for the Upper Paleozoic natural gas-reservoir in Ordos basin is studied in the first time, using LA-ICP-MS techniques of in situ U-Pb dating, accompanied with heavy and detrital mineral analysis and detrital mineral cathodoluminescence measurement, as well as comparative study of isotopic chronology of the parent rocks in provenance. Types of sandstones, detrital minerals and cements, pore types and reservoir quality of the different three sandstone types and their horizontal distribution characteristics are elucidated in this study, based upon robust core observation and description and depositional facies investigation, identification and quantitative statistics from sandstone thin sections under microscope, analysis of grain size, porosity and permeability, and capillary pressure measurement. Furthermore, provenance and parent rock chronology, impact of parent rock features, depositional facies, sedimentation and hydrodynamic condition on formation of excellent gas-reservoir and on reservoir quality evolution is also discussed in the paper. This study may answer to problem of provenance and parent rocks for the Upper Paleozoic, and understand controlling parameters for formation and evolution of excellent gas-reservoirs in Ordos basin. It is important to thoroughly examine deposition and tectonic evolution in northern part of the Ordos basin, and to predict prospect natural gas-rich area and promote exploration and development for hydrocarbon resources in the Ordos basin.