Weihe Basin Drilling Project (WBDP): Cenozoic tectonic-monsoon interactions

Earth’s climate underwent dramatic cooling throughout much of the Cenozoic, which has been linked to continental drift, mountain building, and the formation and expansion of ice-sheets in Antarctica and the Arctic. In particular, the India-Asia collision and uplift of the Tibetan Plateau (TP) have been posited as critical events responsible for increasing the rates of physical and chemical weathering on land, thereby decreasing the CO2 concentration of the atmosphere. The uplift of the TP ultimately led to the onset of the complexly coupled monsoon-arid environmental system in East Asia. Global-scale studies of Cenozoic deep-sea sediments and Quaternary ice cores indicate that, superimposed to the long-term cooling trend, climate variability at orbital-to-centennial time-scales is primarily induced by changing solar insolation and irradiance, and strongly modulated by complex internal land-air-ocean interactions. From the continental perspective, however, both the dynamics and impacts of long-term climate evolution and short-term climate variability remain poorly constrained due to the paucity of continuous terrestrial sequences spanning the entire Cenozoic.
The Weihe Basin is located in the monsoon-sensitive region to the north of the Qinling Mountains, a landform that constitutes the geographic and climatic boundary between northern and southern China. In the depocentre of this basin, a predominantly lacustrine sedimentary sequence with a thickness of >7 km, provides an unprecedented opportunity for: (1) reconstructing tectonic-to-millennial-scale climate changes from the Eocene to the present; (2) elucidating basin-mountain coupling processes; (3) assessing the effects of Cenozoic tectonic-climate interactions on the onset and evolution of the Asian paleomonsoon; and (4) investigating climatic/environmental impacts on the evolution of microbial communities. Importantly also, (5) sedimentary filling of the Weihe Basin can potentially yield unique high-resolution records of continental climate variability during high atmospheric CO2 periods of the Eocene, mid-Miocene, and Late Pliocene, and thus serve an analog for Earth’s near future climate.
The Weihe Basin Drilling Project (WBDP) proposes a two-phase drilling strategy to recover a complete as possible Cenozoic terrestrial sedimentary record from the eastern Weihe Basin depocenter. In the first phase (applied for here) we aim at producing a 3-km-long pilot sedimentary record (WBDP-1) to test the best suitable analytical approach and to reconstruct orbital-to-millennial-scale climate variability since the Late Miocene. In the second phase our aim is to produce a 7.5-km-long sedimentary record (WBDP-2) spanning the entire Cenozoic sedimentary infill of the Weihe Basin. The regional geological framework is well characterized through numerous exploration boreholes and detailed multichannel seismic reflection surveys. Scientific drilling operations will be accompanied by downhole logging, as well as on- and off-site analyses of the retrieved cores. The WBDP-1 borehole is expected to yield a world-class paleoclimate record for the last ~10 Ma and lead to fundamental advances in our understanding of multi-timescale climate variability and tectonic-climate monsoon linkages. The project will also enhance public awareness of human adaptation to Earth’s changing environment.