Lake Qinghai is the largest interior plateau lake in North China, and is sensitive to climate change and the environmental effects of Tibetan Plateau uplift. An almost continuous 626 m long sediment core have been obtained from an in-filled part of the southern lake basin, which documents both the age of the origin of the lake and the evolution of the East Asian monsoon during the Late Cenozoic. The article presents a high-resolution magnetostratigraphy work which provides a chronology back to about 5.1 million years ago. Analysis of lithofacies and depositional environments reveal that the change from eolian to lacustrine facies occurred ~4.63 million years ago, corresponding to a shift from an arid/semi-arid to a more humid climate, which resulted in the origin of Lake Qinghai. Changes in sediment lithology and mean grain-size indicate that the lake level fluctuated considerably, superimposed on a long-term trend from higher to lower levels in response to variations in the East Asian Monsoon. This archive is a significant additional source of information on regional and global environmental change, complementing the existing records from North China which are mainly based on analysis of loess deposits. This study is extremely important, because long, continuous, terrestrial lacustrine sedimentary records are extremely rare.
Restraining bend tectonics in the Santa Cruz Mountains, California, imaged using 10Be concentrations in riv
|Contact: Kea Giles|
Geological Society of America