Seminar

Knowledge of pre-Quaternary warm climates is highly important for understanding global changes that we will face in the future. The Miocene epoch, ~23-5 million years ago (Ma), is one of the substantially warm periods in Earth’s climate history that could provide clues to future climatic changes and impacts. However, important issues including environmental and topographic evolution on the Tibetan Plateau and ventilation changes in the ocean remain poorly resolved. In this study, via the utilization of multiple biomarkers, we revealed 1) detailed lake evolution in the Qaidam and Lunpola Basins on the Tibetan Plateau during the Miocene. Results indicate that global climatic conditions might have controlled the lake status during the period, whereas tectonic activities might have also contributed to the long-term demise; 2) occurrence of the marine biomarker Group III alkenone in the Qaidam Basin during the mid-Miocene. It appears to be plausible that seawater occasionally intruded into the basin during the mid-Miocene, indicative of a lowland basin floor close to sea-level height; 3) contrasting ventilation changes in global oceans across the mid-Miocene climate transition. The improvement of ventilation in low-latitude oceans might have resulted from a reduced thermal gradient associated with global cooling, whereas reduced ventilation in mid- to high-latitude oceans appears to be linked to a more sluggish meridional overturning circulation.

Additional information: Mr LIANG Yu, yuliang7@connect.hku.hk