Extreme weathering/erosion during the Miocene Climatic Optimum: Evidence from sediment record in the South China Sea

• Published in: Geophysical Research Letters
• Main Authors: Wan, Shiming, Kurschner, Wolfram M., Clift, Peter D., Li, Anchun, Li, Tiegang
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Atmospheric Carbon-dioxide; Late Cenozoic Uplift; Himalayan Erosion; 20 Ma; Evolution; Burial; Rates; Asia; Vegetation; Paleosols; Geosciences; Multidisciplinary; Antarc*; Antarctic; Ice Sheet
• Online Access: http://ir.qdio.ac.cn/handle/337002/3701; https://doi.org/10.1029/2009GL040279

Investigating the interplay between continental weathering and erosion, climate, and atmospheric CO(2) concentrations is significant in understanding the mechanisms that force the Cenozoic global cooling and predicting the future climatic and environmental response to increasing temperature and CO(2) levels. The Miocene represents an ideal test case as it encompasses two distinct extreme climate periods, the Miocene Climatic Optimum (MCO) with the warmest time since 35 Ma in Earth's history and the transition to the Late Cenozoic icehouse mode with the establishment of the east Antarctic ice sheet. However the precise role of continental weathering during this period of major climate change is poorly understood. Here we show changes in the rates of Miocene continental chemical weathering and physical erosion, which we tracked using the chemical index of alteration ( CIA) and mass accumulation rate ( MAR) respectively from Ocean Drilling Program (ODP) Site 1146 and 1148 in the South China Sea. We found significantly increased CIA values and terrigenous MARs during the MCO (ca. 17-15 Ma) compared to earlier and later periods suggests extreme continental weathering and erosion at that time. Similar high rates were revealed in the early-middle Miocene of Asia, the European Alps, and offshore Angola. This suggests that rapid sedimentation during the MCO was a global erosion event triggered by climate rather than regional tectonic activity. The close coherence of our records with high temperature, strong precipitation, increased burial of organic carbon and elevated atmospheric CO(2) concentration during the MCO argues for long-term, close coupling between continental silicate weathering, erosion, climate and atmospheric CO(2) during the Miocene. Citation: Wan, S., W. M. Kurschner, P. D. Clift, A. Li, and T. Li (2009), Extreme weathering/ erosion during the Miocene Climatic Optimum: Evidence from sediment record in the South China Sea, Geophys. Res. Lett., 36, L19706, doi:10.1029/2009GL040279. Investigating the ...