10Be/9Be constrain of varying weathering rate since 5 Ma: evidence from a Co-rich ferromanganese crust in the western Pacific

• 作者: Li-Feng Cui Ying Hu Ke-Jun Dong Sheng Xu Cong-Qiang Liu Hai-Bin Wu
• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: SHORT COMMUNICATIONS
• 页码范围: 664-666
• 页数: 3页
• 语种: 英文

摘要

The most significant events since the Cenozoic were the cooling of global climate and decreasing CO2 concentrations in the atmosphere [1].The link of these events has often been attributed to the removal of CO2 by increased uplift and erosion of plateau/mountains, and thus consequent increases in silicate weathering [2] and organic carbon burial [3]. Recently, many studies of the late Cenozoic weathering rate have resulted in two completely different views: a significant increase versus long-term stable rates.Sedimentary records suggest that global weathering rates have been enhanced with the worldwide erosion rates accelerating by a factor of 2-10 since the Miocene with the plateau/mountain uplift and global cooling [2,4-6].However, these studies, which emphasise a major influence of tectonic uplift and glaciation on the global weathering rates, have been challenged by records of global oceanic 10Be/9Be ratios.Considered as a powerful proxy of continental weathering flux, the oceanic 10Be/9Be ratios were found to be nearly constant over the last ～12 Ma [7,8], suggesting that the tectonic uplift and global cooling would have no profound effect on global weathering rates.Apparently, a constant weathering flux, which was deduced by the relatively low resolution analysis, cannot exclusively explain why the simultaneous decrease in the partial pressure of CO2 occurred or why weathering flux remained constant even with the tectonic uplift and global climate cooling [9].Thus, these views arise in questions as to whether an increase in global weathering rate actually occurred during the late Cenozoic.Therefore, such discrepancy leads to uncertainty concerning the hypothesized global weathering rate controlled by either tectonic uplift or climatic changes.