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

• Published in: Geophysical research letters Vol. 36; no. 19; pp. L19706 - n/a
• Main Authors: Wan, Shiming, Kürschner, Wolfram M., Clift, Peter D., Li, Anchun, Li, Tiegang
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.10.2009; Blackwell Publishing Ltd; John Wiley & Sons, Inc
• Subjects: atmospheric CO2; Atmospherics; Biogeosciences; Carbon; Carbon cycling; Carbon dioxide; China; Climate; Earth sciences; Earth, ocean, space; Erosion; Erosion and weathering; Exact sciences and technology; Geobiology; Geochemistry; Geological time; Information Related to Geologic Time; Miocene Climatic Optimum; Neogene; Optimization; Planetary Sciences; Planetology; Planets; Sedimentary geochemistry; Sedimentary geology; Sedimentation; Solid Surface Planets; Weathering; Alps; South China Sea; Angola; West Pacific; Asia; Europe; Africa; polar regions; Antarctica; Pacific Ocean; Central Africa; Antarctic ice sheet; ISEW, South China Sea; ASE, Angola; atmospheric CO 2; Miocene Climatic Optimum; weathering; Neogene; chemical weathering; upper Tertiary; global; Earth; Mars; Accumulation rate; burial; temperature; tectonics; Cenozoic; climate change; atmospheric precipitation; Tertiary; Regional scope; concentration; climate; trajectory; high temperature; sedimentation; offshore; extreme value; erosion; Ocean Drilling Program; cooling; Miocene; Phanerozoic; middle Miocene
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2009GL040279

Investigating the interplay between continental weathering and erosion, climate, and atmospheric CO2 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 CO2 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 CO2 concentration during the MCO argues for long‐term, close coupling between continental silicate weathering, erosion, climate and atmospheric CO2 during the Miocene.