Abstract
Abstract. The Weihe Basin, enclosed by the Chinese Loess Plateau to the north and the Qinling Mountains to the south, is an outstanding, world-class continental site for obtaining high-resolution multi-proxy records that reflect environmental changes spanning most of the Cenozoic. Previous geophysical and sedimentary studies indicate that the basin hosts 6000–8000 m thick fluvial–lacustrine sedimentary successions spanning the Eocene to Holocene. This sedimentary record provides an excellent and unique archive to decipher long-term tectonic–climate interactions related to the uplift of the Tibetan Plateau, the onset/evolution of the Asian monsoon, and the development of the biogeography of East Asia. Owing to its location at the interface of the opposing westerly and Asian monsoon circulation systems, the Weihe Basin also holds enormous promise for providing a record of changes in these circulation systems in response to very different boundary conditions since the Eocene. To develop an international scientific drilling programme in the Weihe Basin, the Institute of Earth Environment, Chinese Academy of Sciences, organized a dedicated workshop with 55 participants from eight countries. The workshop was held in Xi'an, China, from 15 to 18 October 2019. Workshop participants conceived the key scientific objectives of the envisaged Weihe Basin Drilling Project (WBDP) and discussed technical and logistical aspects as well as the scope of the scientific collaboration in preparation for a full drilling proposal for submission to the International Continental Scientific Drilling Program (ICDP). Workshop participants mutually agreed to design a two-phase scientific drilling programme that will in a first phase target the upper 3000 m and in a second phase the entire up to 7500 m thick sedimentary infill of the basin. For the purpose of the 7500 m deep borehole, the world's only drill rig for ultra-deep scientific drilling on land, Crust 1, which previously recovered the entire continental Cretaceous sediments in the Songliao Basin, will be deployed in the WBDP.
Highlights
The Earth has experienced remarkable climate and environmental changes during the last 65 million years
Against the backdrop of global cooling during the Cenozoic, the salient trend in Asia was the development of the coupled monsoon–arid environment system at tectonic timescales, which was largely driven by a reorganization of atmospheric circulation systems in response to the India–Asia collision and the subsequent uplift of the Tibetan Plateau, and the global cooling (Kutzbach et al, 1993; Ramstein et al, 1997, An et al, 2001; An, 2014; Lu et al, 2010)
To date a continuous Cenozoic record capturing both the effects of global climate change and regional tectonics on Asian climate has yet to be recovered. Such a record is critical for enhancing our knowledge about when and how the Asian monsoon originated while at the same time enabling assessment of the mechanism of tectonic–climate interactions through the entire Cenozoic era
Summary
The Earth has experienced remarkable climate and environmental changes during the last 65 million years. Due to the stepwise growth of the northern Tibetan Plateau during the late Cenozoic, a series of tectonic basins were developed in the surrounding areas, such as the Tarim Basin (Sun et al, 2009; Liu et al, 2014), Qaidam Basin (Yin et al, 2008; Zhang et al, 2012), Xining Basin (Fang et al, 2019), Linxia Basin (Fang et al, 2003), and Lanzhou Basin (Yue et al, 2001) Thick deposits of these basins provide direct evidence of a Cenozoic drying history of inland Asia (Dupont-Nivet et al, 2007; Wang et al, 2012; Liu et al, 2014; Li et al, 2014). Owing to its continuity in sediment deposition, the Weihe Basin is ideally suited to producing a critically important record capable of elucidating the effect of global-scale climate and regional-scale tectonics on the evolution of the major atmospheric circulation systems in Asia and the response of eco-environmental systems to high atmospheric greenhouse gas concentrations during several critical warm periods Owing to its eastern location, the sedimentary record of the Weihe Basin holds promise for identifying potential imprints of major uplift and exhumation events of the Tibetan Plateau, which played significant roles in the formation and evolution of the Asian monsoon–arid environmental systems (An et al, 2001, 2015)
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