Lithology and U–Pb Geochronology of Basement of Cenozoic Yitong Basin in Northeastern China: Implication for Basin Architecture and New Horizon of Deep Natural Gas Exploration

Abstract

The lithology and formation age of basement rocks are significant for the understanding of the nature of basin architecture, evolution and the potential of hydrocarbons of a basin. In this study, the basement lithology of the Cenozoic Yitong Basin is investigated through the petrological analysis of cores, cuttings, and thin sections. The results suggest that the basement rocks of the Yitong Basin are mostly composed of unique igneous rocks that are different from nearby basins’ sedimentary and metamorphic basement. The igneous rocks are dominated by intrusive monzonite granite and alkali feldspar granite. Additionally, U–Pb zircon geochronology of basement samples by LA-ICP-MS and the geological interpretation of apparent resistivity data indicate that the igneous basement in major part of the basin was mainly formed by a lateral intrusion of granite into the Permian sedimentary stratum in the Yanshanian period from 177 to 170 Ma. The results also reveal the two-layer basin architecture with coal-bearing Carboniferous–Permian strata below the igneous basement covered with Tertiary sediments, thus providing a new geologic horizon for deep natural gas exploration in the older coal-bearing sedimentary rocks beneath the current igneous basement.