Changes in chemical weathering regime of shelf sediments of the East China Sea controlled by sea-level and climatic changes since the last deglaciation
Kai Lan , Xiting Liu , Anchun Li , Fangjian Xu , Peijun Qiao , Houjie Wang
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引用次数: 0
Abstract
Chemical weathering of shelf sediments is important in driving the global elemental cycle and climate to maintain the earth’s habitability. However, the response mechanism between chemical weathering of shelf sediments and climate and sea-level changes is still unclear. This study focuses on core ECMZ located in the mud area of the East China Sea (ECS) inner shelf. The results indicate that the mechanisms controlling chemical weathering in the sediment of the ECS inner shelf differ at different timescales. On the orbital time scale, the Chemical Index of Alteration (CIA) indicates that the intensity of chemical weathering in sediments during the deglacial period was significantly higher than that during the Holocene. This was caused by shelf exposure during low sea-level periods when the sediments were fully exposed and the residence time in the weathering zone was long, leading the shelf sediments to undergo consistent and complete weathering under supply-limited conditions. In comparison, during cold events on the millennium-centennial time scale, such as Younger Dryas, 8.2 ka, and 4.2 ka, chemical weathering was weaker (lower CIA values) due to accelerated erosion as a result of lower temperatures and higher precipitation, which shortened the rocks’ residence in the weathering zone, resulting in the control of chemical weathering shifted from supply factors to kinetic ones, such as temperature and precipitation. Our findings suggest that on the orbital time scale, glacial shelf exposure could enhance chemical weathering, thereby reducing atmospheric CO2; on the millennium-centennial time scale, chemical weathering could rapidly respond to abrupt climate events.
期刊介绍:
Journal of Asian Earth Sciences has an open access mirror journal Journal of Asian Earth Sciences: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review.
The Journal of Asian Earth Sciences is an international interdisciplinary journal devoted to all aspects of research related to the solid Earth Sciences of Asia. The Journal publishes high quality, peer-reviewed scientific papers on the regional geology, tectonics, geochemistry and geophysics of Asia. It will be devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be included. Papers must have international appeal and should present work of more than local significance.
The scope includes deep processes of the Asian continent and its adjacent oceans; seismology and earthquakes; orogeny, magmatism, metamorphism and volcanism; growth, deformation and destruction of the Asian crust; crust-mantle interaction; evolution of life (early life, biostratigraphy, biogeography and mass-extinction); fluids, fluxes and reservoirs of mineral and energy resources; surface processes (weathering, erosion, transport and deposition of sediments) and resulting geomorphology; and the response of the Earth to global climate change as viewed within the Asian continent and surrounding oceans.