Bathyal records of enhanced silicate erosion and weathering on the exposed Luzon shelf during glacial lowstands and their significance for atmospheric CO2 sink
Bathyal records of enhanced silicate erosion and weathering on the exposed Luzon shelf during glacial lowstands and their significance for atmospheric CO2 sink
复制标题
冰川低位期间暴露的吕宋陆架上硅酸盐侵蚀和风化增强的深海记录及其对大气二氧化碳汇的意义
DOI：
10.1016/j.chemgeo.2017.11.027
复制
发表时间：
2018
期刊：
影响因子：
3.9
通讯作者：
Dhongil Lim
中科院分区：
文献类型：
--
作者：
Zhaokai Xu;Tiegang Li;Peter D. Clift;Shiming Wan;Xiaohua Qiu;Dhongil Lim
我们提出了位于菲律宾西部大陆坡的国际海洋全球变化研究核心 MD06-3052 的质量积累率、Sr-Nd 同位素以及硅质碎屑沉积物部分的主要和微量元素的新高分辨率多代理数据集。我们将新数据与已发布的同一核心的颗粒尺寸和海面温度以及赤道太平洋海平面和东亚夏季季风降水相结合，以便以高分辨率限制吕宋岛物理侵蚀和化学风化强度以及沉积物从源到汇过程的变化。我们评估了距今 156 kyr 以来弧硅酸盐化学风化在调节全球大气二氧化碳方面的潜在重要性。 Sr-Nd 同位素显示，硅质碎屑沉积物主要源自吕宋岛暴露的火山岩 (~ 68–100%)，亚洲尘埃的贡献较小 (~ 0–32%)。不同的指数表明，海洋同位素阶段（MIS）6（距今130-156 kyr）以及MIS 3和MIS 2后期（距今14-40 kyr）发生了更强的物理侵蚀和化学风化。在这两个寒冷时期，海平面低位和与之相关的菲律宾海西部大陆架的显着暴露应该有利于暴露陆架上松散沉积物的物理侵蚀和化学风化。此外，我们注意到在这些寒冷时期吕宋岛的化学风化强度与全球大气二氧化碳浓度之间具有相对较好的一致性。我们认为，第四纪冰川海平面低位期间吕宋岛和其他热带弧（赤道20°以内）硅酸盐化学风化作用的加强可能会显着促进冰河时期大气二氧化碳浓度的降低。我们估计，最终由硅酸盐风化封存的所有大气二氧化碳中，有很大一部分，高达约 16%（即约 8 ppmv），可以通过仅相当于全球放热排水面积约 1% 的区域进行处理。
We present a new high-resolution multiproxy data set of mass accumulation rates, Sr-Nd isotopes, as well as major and trace elements for the siliciclastic sediment fraction from International Marine Global Change Study Core MD06-3052, located on the continental slope of the western Philippine Sea. We integrate our new data with published grain sizes and sea surface temperatures from the same core, as well as with Equatorial Pacific sea level, and East Asian summer monsoon precipitation, in order to constrain at high-resolution changes in physical erosion and chemical weathering intensities on Luzon, and sediment source-to-sink processes. We assess the potential significance of chemical weathering of arc silicates in regulating global atmospheric CO2since 156 kyr BP. Sr-Nd isotopes show that the siliciclastic sediments were dominantly sourced from volcanic rocks exposed on Luzon (~ 68–100%), with a lesser contribution from Asian dust (~ 0–32%). Different indices indicate that stronger physical erosion and chemical weathering occurred during Marine Isotope Stage (MIS) 6 (130–156 kyr BP), as well as in the latter stage of MIS 3 and MIS 2 (14–40 kyr BP). The large sea-level lowstands and associated significant exposure of continental shelf in the western Philippine Sea during these two cold periods should favor physical erosion and chemical weathering of unconsolidated sediments on the exposed shelf. Furthermore, we notice the relatively good coherence between chemical weathering intensities on Luzon and global atmospheric CO2concentrations over these cold intervals. We suggest that strengthening of chemical weathering of silicates on Luzon and other tropical arcs (within 20° of the Equator) during the Quaternary glacial sea-level lowstands may significantly contribute to the lowering of atmospheric CO2concentrations during ice ages. We estimate that a significant fraction, up to ~ 16% (i.e., ~ 8 ppmv), of all atmospheric CO2ultimately sequestered by silicate weathering may be processed through an area corresponding to only ~ 1% of the exorheic drainage area worldwide.