亚洲主要河流的沉积地球化学示踪研究进展

发源于喜马拉雅—青藏高原的亚洲几条大河的河流地球化学研究揭示了高原隆升、流域风化剥蚀、大气CO2消耗和亚洲季风气候变化之间的耦合关系。研究认为南亚主要河流流域的化学风化对全球大气CO2消耗和海洋化学通量变化贡献较大，河流沉积地球化学研究反映的高原阶段性隆升过程、流域剥蚀速率以及亚洲季风演化信息也明显比东亚主要河流的记录清晰；尤其是最近几年运用河流碎屑单矿物化学和年代学方法来示踪流域构造演化、沉积物从源到汇过程以及河流演化历史等，取得了许多重要的研究成果。比较而言，我国的河流在元素地球化学和水化学组成方面虽然开展了大量基础研究工作，但目前急需进一步提炼科学目标，与国际性的研究计划结合，综合多学科的研究力量，在研究思路和关键方法上需要突破和深入，加强研究的广度和深度。长江更可以作为一个突破口和研究平台，来开展深入的沉积地球化学示踪研究。

Advances in Sedimentary Geochemistry and Tracing Applications of Asian Rivers

In the past decades one of the research highlights of earth system science and global changes is Tibetan Plateau uplift and the corresponding global climate changes during the Cenozoic. The mega-rivers originated from the Himalayan-Tibetan Plateau transport huge amount of particulate and dissolved matters eroded from the plateau and its surrounding regions into the marginal seas of Asia and, therefore, exert a great control on source to sink process of terrigenous materials. Geochemical tracing studies of these rivers provided important constraints on the uplift history of the Tibetan Plateau, weathering intensity and atmospheric CO2 sink in the drainage basins, and chemical flux change of global ocean. Furthermore, sedimentary geochemical studies in the estuaries, based upon the bulk geochemical proxy idices and mineral chemistry and age spectrum of zircon, monazite and apatite, reconstructed the growth cycles of the upper continental crust exposed to weathering and deciphered the evolution history of these rivers. Comparatively, geochemical tracing studies on Chinese rivers were triggered about ten years ago and mostly focused on elemental geochemistry of the Changjiang and Huanghe. Recent research work suggested that the silicate weathering rate and the corresponding CO2 sink in the Huanghe drainage basin are lower than those in the south Asian river basins. Nevertheless, more work are needed in order to better understand the contributions of chemical weathering in Chinese river basins to global climate change. Among Chinese major rivers, the Changjiang which has complex drainage patterns and source rock compositions, deserves more research attentions from multi-discipline and using various research methods. The development history and the sedimentary response of the Changjiang to the Tibetan Plateau uplift and East Asian monsoon evolution should be considered first in the future study.