[U-02] 人新世・第四紀の気候および水循環

[U02-05] Stalagmite-inferred silicate weathering in southern China from 142 to 114 thousand years ago

★Invited Papers

Meng Zhang¹、Xiuyang Jiang^2,3、*Chuan-Chou Shen^4,5、Fengtai Tong^6,7、Yang-Yang Wang¹、Yilin Xiao¹ (1.School of Earth and Space Sciences, University of Science and Technology of China, Hefei, People’s Republic of China、2.College of Geography Science, Fujian Normal University, Fuzhou, People’s Republic of China、3.Institute of Geography, Fujian Normal University, Fuzhou, People’s Republic of China、4.Department of Geosciences, National Taiwan University, Taipei, Taiwan, Republic of China、5.Research Center for Future Earth, National Taiwan University, Taipei, Taiwan, Republic of China、6.International Center for Isotope Effects Research, Nanjing University, Nanjing, People’s Republic of China、7.School of Earth, Sciences and Engineering, Nanjing University, Nanjing, People’s Republic of China)

キーワード：Silicate weathering, Asian monsoon, Penultimate deglaciation, Stalagmite lithium isotope record

Terrestrial silicate weathering is one of the most geological processes on land. Studies showed strong monsoonal intensity during interglacial periods may enhance weathering compared to glacial periods; while others argued little glacial-interglacial variation. This ongoing debate lies the poorly understood links between silicate weathering and monsoon evolution during deglaciation. Here, we present stalagmite lithium isotopic records from southern China during 142-114 thousand years ago (ka) to investigate silicate weathering dynamics through the penultimate deglaciation. Our results show a sharp decline in weathering at 136 ka, coinciding with the beginning of a weakened 6-kyr Asian monsoon interval (WMI). Surprisingly, weathering subsequently intensified during this weak monsoonal phase, and then increased from 129 ka and reached its summit at 120 ka within the period of marine isotope stage 5e at ~129-117 ka. We propose that the decoupled enhancement of weathering during the WMI was likely driven by insolation-induced temperature rise, while the continuous intensification of weathering during MIS 5e resulted from both elevated precipitation and temperature. These findings indicate a complicated response of the silicate weathering process response to deglaciation than previously thought. Additional proxy records are required for an in-depth understanding of glacial-interglacial silicate weathering processes.