Linda A. Hinnov
Professor of Geology
Department of Atmospheric, Oceanic and Earth Sciences
George Mason University

Eocene-Oligocene Jianghan Basin, central China:

The Upper Eocene-Lower Oligocene Qianjiang Formation of the Jianghan Basin, central China consists of a 4700-m-thick lacustrine succession that includes 1800 m of halite-mudstone cycles. Professor Chunju Huang of China University of Geosciences (Wuhan) has identified eight third-order depositional sequences based on pinch-out and onlap stratigraphic patterns in seismic data and well logs. The basin cycled repeatedly between saline and freshwater lake systems, caused by availability of accommodation space controlled by a combination of climate change, tectonic subsidence and sediment supply (Huang and Hinnov, 2014).

The halite-mudstone cycles occurred at Milankovitch timescales and show strong influence from the Earth's astronomical variations. Moreover, there is evidence for more pronounced and extended episodes of "aridity" and "humidity" that appear to be linked with oceanic events of "warming" and "cooling". The timing of these land-ocean events is currently under investigation (Huang and Hinnov, in preparation).

Stratigraphic column summarizing lithostratigraphy, depositional systems, source-reservoir-seal associations, stratigraphic units, and third-order depositional sequences in the Qianjiang depression, Jianghan Basin, China. (From Huang and Hinnov, 2014.)