The influence of climate and topography on chemical weathering of granitic regoliths in the monsoon region of China  

作　　者：Hairuo Mao Zhiqi Zhao Lifeng Cui Congqiang Liu 

机构地区：[1]State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry, Chinese Academy of Sciences,Guiyang 550081, China [2]University of Chinese Academy of Sciences, Beijing 100049,China

出　　处：《Acta Geochimica》2018年第5期758-768,共11页地球化学学报（英文）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41210004;41661144042; 41603018);National Basic Research Program(973project)of China(2013CB956401)

摘　　要：Exploring the relationship between weathering and erosion is essential for understanding the evolution of landscapes and formation of soil under the influence of climate, tectonics, and topography. We measured the bulk chemistry of regoliths and calculated their weathering rates and intensity in three locations in China: Inner Mongolia in the mid-temperate semi-humid zone; Jiangxi Province, in the mid-subtropical humid zone; and Hainan Province, in the tropical humid zone. These profiles exhibited increased weathering with increasing temperature and precipitation.The low-gradient profile exhibited stronger weathering of saprolite than of soil, whereas the high-gradient profile showed a more constant weathering pattern. The regolith in the cold climate was the product of easily weatherable minerals, whereas weathering of K-feldspar and even secondary minerals occurred in hot and humid climates. The weathering of subtropical profiles was both supply-and kinetic-limited, controlled by weathering and erosion. The tropical profile experienced supply-limited weathering,indicating slow erosion and an intense weathering profile;the mid-temperate profile was not classifiable due to weak erosion and weathering. Long-term weathering fluxes of these profiles show that Si, Na, and K(or Mg) represent thebulk of the mass lost through weathering. This study underscores that weathering of granitic regolith is controlled by both climatic conditions and landscape.Exploring the relationship between weathering and erosion is essential for understanding the evolution of landscapes and formation of soil under the influence of climate, tectonics, and topography. We measured the bulk chemistry of regoliths and calculated their weathering rates and intensity in three locations in China： Inner Mongolia in the mid-temperate semi-humid zone; Jiangxi Province, in the mid-subtropical humid zone; and Hainan Province, in the tropical humid zone. These profiles exhibited increased weathering with increasing temperature and precipitation. The low-gradient profile exhibited stronger weathering of saprolite than of soil, whereas the high-gradient profile showed a more constant weathering pattern. The regolith in the cold climate was the product of easily weatherable minerals, whereas weathering of K-feldspar and even sec- ondary minerals occurred in hot and humid climates. The weathering of subtropical profiles was both supply- and kinetic-limited, controlled by weathering and erosion. The tropical profile experienced supply-limited weathering, indicating slow erosion and an intense weathering profile; the mid-temperate profile was not classifiable due to weak erosion and weathering. Long-term weathering fluxes of these profiles show that Si, Na, and K （or Mg） represent the bulk of the mass lost through weathering. This study underscores that weathering of granitic regolith is con- trolled by both climatic conditions and landscape.

关 键 词：Granitic regolith Chemical weathering Supply-limited weathering Kinetic-limited weathering 

分 类 号：P588.121[天文地球—岩石学] P512.1[天文地球—地质学]