Geology of the Asian Monsoons: A deep-time perspective

Map of the monsoonsWhen did the modern (monsoonal) Asian atmospheric circulation start?

Context: The Asian Monsoon is primarily driven by continent-ocean thermal contrasts, and frequent meteorological extreme events emphasize that it is affected by recent climate change responding to increasing atmospheric level of carbon dioxide (pCO2). The medium to longer-term effects of changes in the monsoonal system control precipitation and aridification in continental Asia and, in the past, shaped Eurasian paleoenvironments and biotic evolution. The Asian monsoons have long been thought to have originated ~23 Myr ago, driven by regional uplift. However, my recent work has shown that the monsoons are more ancient than previously thought and were possibly active with patterns similar to today during the high pCO2 Eocene Greenhouse episode. These studies open a vast array of new questions: (1) How did these early monsoons evolve through the Eocene? (2) How did they react to the numerous, short-term hyperthermal and hypothermal pCO2 events that ruled this period? This research project proposes to address these issues by focusing on different key sedimentary records in the Eocene monsoonal realm. Key sections in China and Myanmar are dated through U/Pb geochronology and investigated with respect to different geochemical and mineralogical paleoclimatic proxies, such as elemental Geochemistry, clay Mineralogy, stable and clumped isotope analyses. This project aims to document the Eocene evolution of rainfall amount, temperature and pCO2 in Asia, with a particular focus on the hyperthermal episodes. The resulting findings will document the short- and long-term variations of the Asian monsoons during the Eocene and in light of Global Change are expected to furnish the basis for a substantial advance in our understanding of monsoonal forcing factors in a warmer world.

In the team: Virginia Littell (Master’s student).dsc_0222

Collaborators: Guillaume Dupont-Nivet, Niels Meijer (Postdam Universität, Germany), Hemmo Abels (TU Delft, The Netherlands), Huasheng Huang, Carina Hoorn (Vrije Universiteit Amsterdam, The Netherlands) Paul Kapp, Alex Pullen (University of Arizona, USA), Dario de Franceschi, Anaïs Boura (Muséum National d’Histoire Naturelle, Paris, France), Kate Huntington, Gerard Roe (University of Washington, USA).