کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5783568 | 1637957 | 2017 | 70 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands: A sink for atmospheric CO2
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
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چکیده انگلیسی
Atmospheric CO2 and global climate are closely coupled. Since 800Â ka CO2 concentrations have been up to 50% higher during interglacial compared to glacial periods. Because of its dependence on temperature, humidity, and erosion rates, chemical weathering of exposed silicate minerals was suggested to have dampened these cyclic variations of atmospheric composition. Cooler and drier conditions and lower non-glacial erosion rates suppressed in situ chemical weathering rates during glacial periods. However, using systematic variations in major element geochemistry, Sr-Nd isotopes and clay mineral records from Ocean Drilling Program Sites 1143 and 1144 in the South China Sea spanning the last 1.1Â Ma, we show that sediment deposited during glacial periods was more weathered than sediment delivered during interglacials. We attribute this to subaerial exposure and weathering of unconsolidated shelf sediments during glacial sealevel lowstands. Our estimates suggest that enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands can account for â¼9% of the carbon dioxide removed from the atmosphere during the glacial and thus represent a significant part of the observed glacial-interglacial variation of â¼80Â ppmv. As a result, if similar magnitudes can be identified in other tropical shelf-slope systems, the effects of increased sediment exposure and subsequent silicate weathering during lowstands could have potentially enhanced the drawdown of atmospheric CO2 during cold stages of the Quaternary. This in turn would have caused an intensification of glacial cycles.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 200, 1 March 2017, Pages 123-144
Journal: Geochimica et Cosmochimica Acta - Volume 200, 1 March 2017, Pages 123-144
نویسندگان
Shiming Wan, Peter D. Clift, Debo Zhao, Niels Hovius, Guy Munhoven, Christian France-Lanord, Yinxi Wang, Zhifang Xiong, Jie Huang, Zhaojie Yu, Jin Zhang, Wentao Ma, Guoliang Zhang, Anchun Li, Tiegang Li,