The effect of Tibetan uplift on the formation and preservation of Tertiary lacustrine source-rocks in eastern China

Abstract

The Cenozoic continental sedimentary basins in eastern China are rich in lacustrine source rocks. Based on their paleogeographic location and fossils, these basins can be grouped into ‘inland’ and ‘near-shore’ basins. Before the collision of India and Eurasia about 45 million years ago, the inland basins were dominated by arid climates that were unfavorable for the substantial preservation of oil source rocks. In contrast, the contemporary near-shore basins experienced alternating arid and humid climates, probably induced by sea level changes, which produced conditions that favoured the formation and preservation of oil source rocks. With the rise of the Tibetan Plateau, the Asian monsoon was initiated or significantly intensified in the Late Eocene. This, in turn, changed the arid climates in the inland basins to humid or to alternating arid and humid, providing ideal conditions for the formation and preservation of lacustrine source rocks in the inland basins. The evidence suggests that Tibetan uplift played a crucial role in the generation and preservation of the Cenozoic lacustrine source rocks in eastern China.