Enhancements of Himalayan and Tibetan Erosion and the Produced Organic Carbon Burial in Distal Tropical Marginal Seas During the Quaternary Glacial Periods: An Integration of Sedimentary Records

Abstract

The Himalayan and Tibetan highlands (mountains), with high rates of physical erosion, are extreme settings for earth surface processes, generating one of the largest recent terrigenous detritus and organic carbon discharges to the ocean. However, their significance with respect to the global carbon and climate cycles during the Quaternary is still unclear, especially in quantitative terms. Here, we present comprehensive records of continental erosion and weathering, terrestrial supply, marine productivity, and organic carbon burial in the distal Arabian Sea, Bay of Bengal, and southern South China Sea since ∼700 ka over orbital timescales. These records exhibit periodicities corresponding to sea level and Indian summer monsoon intensity changes. During glacial periods, the enhanced highland surface erosion and activation of deep-sea channels significantly increased inputs of terrigenous detritus, nutrients, and organic carbon into the Arabian Sea and Bay of Bengal, whereas strengthened continental shelf surface weathering and organic matter preservation occurred in the South China Sea. Conclusively, our integrative proxies in the study area demonstrate, for the first time, pronounced glacial burial pulses of organic carbon (∼1.12 × 10 12 mol/yr), dominantly originating from the highland surface erosion and marine productivity. Together with the increased silicate weathering on the exposed tropical continental shelves and in the tropical volcanic arcs, the enhanced burial flux of organic carbon in the tropical marginal seas, therefore, highlights the large contributions that tropical regions can make within the glacial-interglacial carbon inventory of the ocean and atmosphere and thus cause significant negative feedback on the global climate. Plain Language Summary Anthropogenic emissions of the greenhouse gas CO 2 are significantly changing the global climate and environment, resulting in a warmer state for which there is no historical analog. Marine records hold valuable lessons for the future of our warming world, as marine sediments are an important reservoir of the global organic carbon and then modulate release of CO 2 into the atmosphere. Currently, the major river systems originating from the Himalaya and Tibetan Plateau discharge ∼25% of the global fluvial sediment flux to the ocean, acting as an important source of continental organic carbon at tectonic and current timescales. Our integrative mineralogicalgeochemical study demonstrates the enhanced highland (mountain) erosion and activation of deep-sea channels, increased supplies of the produced materials, strengthened marine productivity, and effective preservation of organic carbon in the deep Arabian Sea and Bay of Bengal during cold periods. In contrast, strengthened chemical decomposition of silicates on the exposed continental shelf was coeval with increased organic carbon storage in the deep South China Sea. The study area contributed ∼1/4 of the current global marine burial flux of organic carbon during sea-level lowstands and thus represents a ...

Geochronology and geochemistry of the Late Jurassic-Early Cretaceous Sangxiu Formation volcanic rocks of the Chegu region, Southern Tibet

“…Vlad Constantin Manea, National Autonomous University of Mexico, Mexico terrigenous detritus and organic carbon that are transported to the oceanic environment, which may exert a discernible impact on global climate change (Xu et al, 2021;Jiang et al, 2023). The Sangxiu Formation is widespread in central segments of the Tethyan Himalayas.…”

Persistent increase in carbon burial in the Gulf of Mannar, during the Meghalayan Age: Influence of primary productivity and better preservation

“…A consistent increase in C org throughout the Meghalayan Age was attributed to increased sedimentation and better preservation under a more reducing environment (Nagoji & Tiwari, 2017). Interestingly, an altogether different pattern with higher C org accumulation during the cold glacials and stadials as compared to low accumulation during the warmer interglacials and interstadials in the neighbouring Bay of Bengal was attributed to intense winter-monsoon-induced increased marine primary production during the colder intervals (Weber et al 2018; Xu et al 2021).…”

Contrasting Sensitivity of Weathering Proxies to Quaternary Climate and Sea‐Level Fluctuations on the Southern Slope of the South China Sea

“…Moreover, continental margins are characterized by rapid sediment accumulation, such that high‐resolution records of past weathering and erosion can potentially be obtained by deciphering the geochemical and mineralogical signatures within these sedimentary successions. Hence, these regions are of great strategic value for research into continent‐ocean interactions and paleoclimate variations over millennial and orbital timescales (Wan et al., 2017; Xu et al., 2021). However, a detailed understanding of the controls on sediment transport, deposition, and burial in these complex environments is a prerequisite for interpreting these sedimentary records and recognizing their implications for the global carbon cycle (Wan et al., 2012; Xu et al., 2018).…”

“…Climate fluctuations during Quaternary glacial-interglacial cycles have significantly influenced the flux and composition of terrigenous sediment supplied to continental shelves, slopes, and deep sea basins, modulated both by changes in precipitation and runoff and by sea level fluctuations (Griffiths et al, 2009;Steinke et al, 2008). For example, studies based on clay mineralogy and sediment geochemistry in the tropical marginal seas (e.g., Arabian Sea, Bay of Bengal, and South China Sea) have revealed increases in terrigenous detrital input, organic carbon burial, and marine productivity during glacial periods, which were linked to the exposure of continental shelves (Xu et al, 2020(Xu et al, , 2021. Because of the association of different terrigenous minerals with different sedimentary grain size fractions (Bao et al, 2019), definitive evidence to test such a sea level hypothesis could be obtained through targeted mineralogical investigations which would enable attribution to hydrodynamic sorting.…”

“…successions. Hence, these regions are of great strategic value for research into continent-ocean interactions and paleoclimate variations over millennial and orbital timescales (Wan et al, 2017;Xu et al, 2021). However, a detailed understanding of the controls on sediment transport, deposition, and burial in these complex environments is a prerequisite for interpreting these sedimentary records and recognizing their implications for the global carbon cycle (Wan et al, 2012;Xu et al, 2018).…”