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chemical weathering in Malay Peninsula and North Borneo:Clay mineralogy and element geochemistry of river surface sediments

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Science China Earth Sciences 2011年第2期54卷 272-282页

作者： WANG Hao LIU ZhiFei Edlic SATHIAMURTHY Christophe COLIN LI JianRu ZHAO YuLong State Key Laboratory of Marine Geology Tongji University Shanghai 200092 China Institute of Oceanography University Malaysia Terengganu Kuala Terengganu 21030 Malaysia Laboratoire IDES Bat. 504 UMR 8148 CNRS Universite de Paris XI Orsay 91405 France

weathering products of silicate rocks are particularly useful for evaluating the continental chemical weathering on the Earth's surface and its *** mineralogy and major-element geochemistry of surface sediment samples collected in major rivers of Malay Peninsula and North Borneo in the tropical Southeast Asian region are used to study the present chemical weathering process and its controlling factors of tropical *** results indicate that the clay mineral assemblage in Malay Peninsula consists dominantly of kaolinite(average 80%) and minor illite(average 17%),almost without chlorite and smectite,whereas in North Borneo it consists mainly of illite and chlorite,with minor amounts of kaolinite(average 14%) and no *** contents of illite and chlorite in both Northwest and Northeast Borneo are 84% and 87%,***-element geochemical results of both bulk and clay-fraction sediments show intensive chemical weathering degree for both ***,the chemical weathering degree is gradually strengthened from Northeast Borneo,Northwest Borneo,to Malay Peninsula,and it is extremely intensive in Malay *** results indicate that,in the tropical Southeast Asian region exampled by Malay Peninsula and Borneo,climatic condition of tropical warm temperature and East Asian monsoon rainfall is the first-order controlling factor on the chemical weathering,resulting in intensive chemical weathering throughout tropical areas,and tectonic activity and lithology of parent rocks are subordinate factors,which still have an important impact on the weathering products,forming completely different clay mineral assemblages between Malay Peninsula and Borneo.

关键词： clay minerals major elements fluvial sediments chemical weathering Malay Peninsula Borneo

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chemical weathering processes in the Chinese Loess Plateau

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Geoscience Frontiers 2024年第5期15卷 197-209页

作者： Ningpan Chai Zhiqi Zhao Xiaoke Li Jun Xiao Zhangdong Jin School of Earth Science and Resources Chang’an UniversityXi’an 710054China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China Xi’an Institute for Innovative Earth Environment Research Xi’an 710061China

Covered by erodible loess and affected by significant seasonal climate variations,chemical weathering in the Chinese Loess Plateau(abbreviated as CLP)has important effects on the hydrochemistry of the Yellow River and the global carbon ***,chemical weathering processes in the CLP are still *** on 296 river water samples in the CLP in the different seasons,hydrochemistry,weathering processes,and their controlling factors were *** waters in the CLP exhibited slightly alkalinity(pH=8.4±0.5)with much high total dissolved solids(TDS)values(691±813 mg/L).The water types of river water in the CLP were primarily SO_(4)^(2-)-Cl^(-)-Na^(+),HCO_(3)^(-)-Ca^(2+)-Mg^(2+),and SO_(4)^(2-)-Cl^(-)-Ca^(2+)-Mg^(2+).According to the forward model,evaporite dissolution has the largest contribution(55.1%±0.2%)to riverine solutes in the CLP,then followed by carbonate weathering(35.6%±0.2%)and silicate weathering(6.5%±0.1%).For spatio-temporal variations,the contribution of evaporite dissolution in the CLP decreased from northwest to southeast with higher proportion in the dry season,carbonate weathering increased from northwest to southeast with a higher proportion in the wet season,and silicate weathering showed minor spatio-temporal ***^(2+)and Mg^(2+)were affected by carbonate precipitation and/or incongruent calcite dissolution,and about 50%of samples exhibited cation exchange *** physical erosion rate in the CLP,which was 372±293 t·km^(-2)·yr^(-1),varied greatly and was greater than those of other worldwide *** weathering rates in the CLP showed an increasing trend *** the wet season,high runoff led to the release of evaporite and carbonate from loess,while the interfacial reaction kinetic limited the increase of the silicate weathering *** CO_(2)consumption budget by carbonate weathering(6.1×10^(10)mol/yr)and silicate weathering(1.6×10^(10)mol/yr)in the CLP accounted for 0.29%and 0.08%of the global carb

关键词： chemical weathering Chinese Loess Plateau Spatio-temporal variations CO_(2)budget Physical erosion

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Mobility of rhenium and selenium during chemical weathering and their implication for petrogenic organic carbon oxidation

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Science China Earth Sciences 2024年第3期67卷 740-750页

作者： Yuhong ZHANG Jin WANG Yuanxin QU Chao ZHU Zhangdong JIN State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China University of Chinese Academy of Sciences Beijing 100049China Xi'an Institute for Innovative Earth Environment Research Xi'an 710061China Institute of Global Environmental Change Xi'an Jiaotong UniversityXi'an 710049China

The oxidative weathering of petrogenic organic carbon(OC_(petro)) is an important source of carbon dioxide(CO_(2)) into the atmosphere on geological timescales and significantly influences the carbon cycle and global climate change. However, at present, a robust proxy to assess OC_(petro)oxidation is lacking. Riverine rhenium(Re) has emerged as a potential proxy to trace OC_(petro)oxidation, but little is known about Re sources and its relationship with OC_(petro)oxidation. To better understand the robustness of this proxy, we analyzed a shale weathering profile from the early Cambrian Shuijingtuo Formation in Chengkou County, Chongqing City, to address the mobility of Re and selenium(Se) and their relationship with the oxidation of OC_(petro)by analyses of the elemental variation and sequential extraction. The results showed that the chemical index of alteration(CIA)increases from the fresh bedrock to the weathered sections, indicating enhanced weathering intensity. Based on the sequential extraction and mass transfer coefficients(τ), Re and Se mainly exist in the organic phase of shale and are paired lost with OC_(petro) during weathering, with no obvious correlation with sulfide minerals. Furthermore, the different proportions of Re and Se loss with OC_(petro) loss can be attributed to their different geochemical behaviors during weathering. Our study supports Re as a robust proxy to trace OC_(petro) oxidation, whereas Se is the potential one. In the future, combined studies on various sedimentary rock profiles with catchment basins are needed to determine the sources of riverine Re and Se and their relationships with OC_(petro) oxidation.

关键词： Rhenium and selenium Shale Mobility OC_(petro) chemical weathering

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Rock chemical weathering by sulfuric acid: pathway, method and prospect

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Acta Geochimica 2017年第3期36卷 474-478页

作者： Dong Zhang Zhiqi Zhao School of Resource and Environment Henan Polytechnic University State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences

To investigate the role of sulfuric acid-based carbonate weathering in global CO_2 sequestration of climate changes, we systematically discussed the pathway of sulfuric acid in rock chemical weathering and its feedback mechanism for global warming. We showed the methods used to determine the accurate amount of sulfate flux,accounting for the sulfuric acid resulted from sulfide oxidation. Finally, we pointed out some prospects for further detailed work on the exact calculation of the sulfate fluxes for the CO_2 net-release.

关键词： chemical weathering Sulfuric acid Global climate change Sulfate isotope

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Weak chemical weathering during the Little Ice Age recorded by lake sediments

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Science China Earth Sciences 2001年第7期44卷 652-658页

作者：金章东王苏民沈吉张恩楼季峻峰李福春 1. Lake Sediment and Environment Laboratory Nanjing Institute of Geography & Limnology Chinese Academy of Sciences 210008 Nanjing China 2. Department of Earth Sciences Nanjing University 210093 Nanjing China

Low magnetic susceptibility, low Sr content and hence high Rb/Sr ratio in the lake sediment sequence indicate a weak chemical weathering process under arid and cold climate of the Little Ice Age in a single closed lake watershed. According to different geochemical behavior between rubidium and strontium in earth surface processes, variation of Rb/Sr ratios in the lake sediment sequence can be used as an effective geochemical proxy with definite climatic significance of chemical weathering in watershed. Unlike chemical weathering process in tropic zone and modern temperate-humid climate, concordant changes in both Sr content and magnetic susceptibility with δ18O values of Dunde ice core suggest that the weak chemical weathering was controlled by air temperature during the Little Ice Age maximum. After the Little Ice Age, chemical weathering intensity was controlled also gradually by precipitation with increasing in temperature.

关键词： closed lake Rb/Sr ratio chemical weathering the Little Ice Age

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Sr isotope evolution during chemical weathering of granites——impact of relative weathering rates of minerals

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Science China Earth Sciences 2001年第8期44卷 726-734页

作者：马英军刘丛强 1. Institute of Geology and Geophysics Chinese Academy of Sciences 100029 Beijing China 2. Institute of Geochemistry Chinese Academy of Sciences 550002 Guiyang China

The Sr isotopic systematics in the weathering profiles of biotite granite and granite porphyry in southern Jiangxi Province were investigated. The results showed that during the chemical weathering of granites, remarked fractionation occurred between Rb and Sr. During the early stages of chemical weathering of granites, the released Sr/Si and Sr/Ca ratios are larger than those of the parent rocks, and the leaching rate of Sr is higher than those of Si, Ca, K, Rb, etc. Dynamic variations in relative weathering rates of the main Sr-contributing minerals led to fluctuation with time in 87Sr/86Sr ratios of inherent and released Sr in the weathering crust of granite. Successive weathering of biotite, plagioclase and K-feldspar made 87Sr/86Sr ratios in the weathering residues show such a fluctuation trend as to decrease first, increase, and then decrease again till they maintain stable. This work further indicates that when Sr isotopes are used to trace biogeochemical processes on both the catchment and global scales, one must seriously take account of the prefer-ential release of Sr from dissolving solid phase and the fluctuation of 87Sr/86Sr ratios caused by the variations of relative weathering rates of Sr-contributing minerals.

关键词： Sr isotope chemical weathering weathering rate non-stoichiometry granite.

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

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Acta Geochimica 2018年第5期37卷 758-768页

作者： Hairuo Mao Zhiqi Zhao Lifeng Cui Congqiang Liu State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081 China University of Chinese Academy of Sciences Beijing 100049China

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 *** 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.

关键词： Granitic regolith chemical weathering Supply-limited weathering Kinetic-limited weathering

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Hydrogeochemistry of River Water in the Upper Reaches of the Datong River Basin,China:Implications of Anthropogenic Inputs and chemical weathering

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Acta Geologica Sinica(English Edition) 2021年第3期95卷 962-975页

作者： WANG Zhenxing LI Xiangquan HOU Xinwei Institute of Hydrogeology and Environmental Geology Chinese Academy of Geological SciencesShijiazhuang 050061China Key Laboratory of Groundwater Sciences and Engineering Ministry of Natural ResourcesShijiazhuang 050061China

This research investigated anthropogenic inputs and chemical weathering in the upper reaches of the Datong River Basin,a tributary of the upper Yellow River,NW *** approaches were applied to data from 52 water and 12 soil samples from the Muli,Jiangcang,and Mole basins to estimate the chemical component concentrations and to analyze hydrochemical characteristics,distribution patterns,and origins in this coal mining-affected river *** mining has enhanced the weathering of the lithosphere in the study *** total dissolved solids in the river range from 145.4 to 701.9 mg/L,which is higher than the global average for *** concentration spatial distributions increase around mining *** geochemistry is mainly controlled by coal mining activity,carbonate weathering,and silicate weathering,with variances of 33.4%,26.2%,and 21.3%,***^(2+),Mg^(2+),and HCO_(3)^(-)are mainly due to the dissolution of carbonate minerals(calcite>dolomite);Si and K+are mainly from potassium(sodium)feldspar weathering;and Na+and SO_(4)^(2-)mainly from coal mine production.A conceptual model of the river water ion origins from the study area is presented and management implications for improving the adverse effects of coal mining are *** results provide an important standard reference for water resource and environmental management in the study region.

关键词： water chemistry chemical weathering major ions coal mining Datong River NE Tibet Plateau

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chemical weathering intensity and element migration features of the Xiashu loess profile in Zhenjiang, Jiangsu Province

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Journal of Geographical Sciences 2008年第3期18卷 341-352页

作者： CHEN Yingyong LI Xusheng HAN Zhiyong YANG Shouye WANG Yongbo YANG Dayuan School of Geographic and Oceanographic Sciences Nanjing University Nanjing 210093 China State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment CAS Xi＇an 710075 China State Key Laboratory of Marine Geology Tongji University Shanghai 200092 China

The chemical weathering intensity and element migration features of the Xiashu loess profile in Zhenjiang are studied in this paper.（1）The Xiashu loess profile underwent moderate chemical *** seems that the precipitation is a more important factor than the temperature in controlling the process of the chemical weathering.（2）The major elements such as Si,K,Na,Ca,Mg,Mn and P were migrated and leached,while the elements Fe and Ti were slightly *** migration features of the major elements reveal that the Xiashu loess finished the primary process of chemical weathering characterized by leaching of Ca and Na,and almost reached the secondary process characterized by leaching of *** the elements Sr and Ga,other trace elements such as Th,Ba,Cu,Zn,Co,Ni,Cr and V were *** might be caused by both the biogeochemical process and the adsorption of trace elements by clay mineral and organic materials.（3）The difference of element migration down the Xiashu loess profile reveals that the climate was warm and wet at the early-middle stage of the middle *** the end of the middle Pleistocene,it became dry and *** the early stage of the Late Pleistocene,the paleoclimate became warm and wet *** a whole,the paleoclimate generally became drier and cooler in this region from the beginning of the middle Pleistocene.

关键词： Xiashu loess chemical weathering element migration Zhenjiang

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chemical weathering in the upper reaches of Xijiang River draining the Yunnan-Guizhou Plateau,Southwest China

Chemical weathering in the upper reaches of Xijiang River dr...

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中国科学院地质与地球物理研究所2007学术年会

作者： Zhifang Xu~a,Cong-Qiang Liu~(b,*) a Institute of Geology and Geophysics,Chinese Academy of Sciences,P.O.BOX 9825,Beijing 100029,China b The State Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guizhou 550002,China

chemical and strontium isotopic compositions of Nanpanjiang River and Beipanjiang River in the upper reaches of Xijiang River draining the Yunnan-Guizhou Plateau,Southwest China,were measured with a main purpose to understand the rock weathering and associated CO consumption rates in the karstic landform-dominated *** chemical ion composition of the river water is characterized by dominance of Ca,Mg and HCO,and SO,which account for more than 90%of total ion ***/Sr ratios of Nanpanjiang River water range between 0.7080 and 0.7140,while those of most Beipanjiang River water,vary within a limited range from 0.7075 to 0.7085. weathering,of carbonate rocks dominate chemistry of major ions especially in the water of Beipanjiang River,whereas weathering of silicate minerals in the upper reaches of Nanpanjiang River basin is obvious in addition to carbonate weathering, mainly according to the Sr isotopic composition of the river *** of the stoichiometry of the river water show that the water chemistry is controlled by carbonate dissolution not only by carbonic but also by sulfuric acid,and indicate that sulfuric acid plays an important role in carbonate *** sulfate in river water is mainly from atmospheric input by coal-combustion industries and from oxidation of sulfide minerals during weathering of coal-containing strata and coal mining in the *** chemical weathering rates of silicate and carbonate and associated CO consumption rates by both carbonic and sulfuric acid and by only carbonic acid are respectively *** results show that chemical weathering rates of carbonate and silicate weathering in Beipanjiang River basin are higher than those of Nanpanjiang River basin,showing linkages of geology and geography in the catchment to crustal *** involvement of sulfuric acid in carbonate weathering greatly enhances the carbonate weathering but lowers the CO consumption rates,indicating that sulfide acid is a

关键词： Yunnan-Guizhou Plateau River water geochemistry Strontium isotope chemical weathering CO2 consumption rate

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