Rapid natural acid weathering, physical erosion, and debris-flow hazards in scar areas developed on hydrothermally-altered rocks along the Red River Valley near Questa, New Mexico, USA     

Geoffrey S. Plumlee Kirk R. Vincent Steve Ludington Philip L. Verplanck D. Kirk Nordstrom 《中国地球化学学报》2006,25(B08):231-232

Prominent erosional scars on hillslopes along the Red River Valley have steep, denuded slopes and associated down-gradient debris fans. The scars developed naturally on stockwork-veined, quartz-sericite-pyrite （QSP）-altered volcanic rocks proximal to porphyry-Mo deposits, including those mined at the Molycorp＇s Questa mine. Downcutting of the Red River, following development of the Rio Grande rift to the west, initiated scar formation. Mineralized rocks in the scars were decomposed chemically （by pyrite oxidation and acid weathering） and physically （by freeze-thaw action and volume expansion from secondary gypsum formation） to produce a weathered veneer of sand- to pebble-size fragments of unweathered rock in a matrix of secondary gypsum, clays, and jarosite. Unoxidized QSP-altered bedrock crops out in steep scar gully bottoms, indicating that the weathered veneer is at most 3-30 m thick. Acidic （pH 2.6 to 4.4）, metal-rich waters develop in the weathered veneer and near-surface bedrock of the scars. Carbonates in the unweathered, QSP-altered bedrock are sufficient to neutralize acid in deeper ground waters, which have near-neutral pH （5.7 to 7.6） and lower metal contents. The scars grow along steep headwalls by slope failure of the weathered veneer.  相似文献   

The erosion-weathering link： New insights from the sediment geochemistry of Himalayan small catchments？     

A. Joshua West Gideon M. Henderson Michael J. Bickle 《中国地球化学学报》2006,25(B08):272-272

The causal links between physical erosion and chemical weathering remain poorly constrained, despite their importance for understanding landscape evolution, nutrient supply for ecosystem development, and the quantitative impact of tectonic uplift on the long-term carbon cycle and Earth＇s climate. This is partly because weathering processes are particularly complicated at high erosion rates, where there are a variety of controlling parameters. The Himalayas provide an ideal natural laboratory for studying weathering processes across an environmental gradient undergoing rapid erosion. We have previously used solute budgets to determine weathering rates in small catchments in the High Himalayas and Middle Hills of central Nepal. In-situ weathering rates are highest in the warmer Middle Hills, while the total riverine budgets suggest that much of the weathering of High Himalayan material must occur after erosion, during transport through the Ganges Plain （West et al., 2002）. Here, we will present new data on the geochemistry of the solid phase （soils and sediments） from these small Himalayan catchments, including time constraints from U-series analysis. This will provide information about the residence time of material in the weathering environment, and its relation to weathering rates.  相似文献   

黑龙江森林沼泽区地球化学亚景观类型划分   总被引：6，自引：0，他引：6  

耿卫华  杨乃峰  马晓阳 《物探与化探》2006,30(4):293-297

森林沼泽景观区条件复杂,亚景观类型众多,长期以来一直缺少大面积区域性的地球化学景观研究工作。根据黑龙江森林沼泽区的特点,从研究森林沼泽区风化作用的主要形式和影响因素出发,对黑龙江森林沼泽区亚景观类型进行了划分。  相似文献   

焦作煤田石炭-二叠纪泥质岩地球化学特征及古环境意义   总被引：2，自引：0，他引：2  

付亚飞  邵龙义  张亮  郭双庆  石彪  侯海海  闫晗  宋建军 《沉积学报》2018,36(2):415-426

泥质岩的地球化学特征蕴含了大量地质信息,在物源和沉积环境分析中的应用十分广泛。利用X射线荧光光谱仪和电感耦合等离子体质谱仪（ICP-MS）对华北板块南缘焦作煤田石炭-二叠纪泥质岩样品进行常量元素、微量元素（包括稀土元素）进行分析,并据此讨论泥质岩的物源性质、物源区岩石风化作用强度及当时古环境特征。研究区泥质岩的高Al₂O₃/TiO₂值及低Cr/Zr和K₂O/Al₂O₃值特征,以及泥质岩Zr-TiO₂和Th/Co-La/Sc源岩判别图、Ni-Cr图和（Gd/Yb）_N-Eu/Eu*图等的判别分析结果,都揭示了研究区泥质岩物源主要为后太古宙长英质岩石;Al₂O₃-CaO*+Na₂O-K₂O（A-CN-K）图和较高的黏土矿物成分反映了泥质岩源区受到钾交代作用的影响,致使CIA（化学蚀变指数）值被低估;高CIW（化学风化指数）值和Al₂O₃-CaO*-Na₂O（A-C-N）判别图分析结果表明泥质岩物源区母岩在石炭-二叠纪经历了强烈的风化作用;Sr/Ba和B/Ga比值变化指示本溪组沉积时期到太原组沉积早期为海相为主的沉积环境,太原组沉积中期到山西组沉积早期为海陆过渡相为主的沉积环境,山西组沉积中期到上石盒子组沉积时期为陆相沉积环境。  相似文献   

大河影响下的陆架边缘海沉积有机碳的再矿化作用   总被引：8，自引：5，他引：3  

姚鹏  郭志刚  于志刚 《海洋学报》2014,36(2):23-32

大河影响下的陆架边缘海(RiOMars)是陆源有机碳的主要沉积汇,是陆海相互作用最重要的区域,在全球碳的生物地球化学循环中发挥着重要作用。受到RiOMars系统内频繁的物理和生物等改造作用的影响,该区沉积的有机碳并没有得到很好地保存而被永久埋藏,而是发生了显著的再矿化分解。本文首先对目前常用的基于O2消耗速率和CO2产生速率的两类测定RiOMars系统沉积有机碳再矿化速率的方法进行了介绍,分析了各自的优缺点和适用性,进而从碳的形态转化、表层沉积物混合均匀、形成次氧化的氧化还原条件、有机碳保存效率低、发生反风化作用和微生物发挥着重要作用等几个方面对RiOMars系统沉积物发生再矿化作用时的主要过程和特征进行了剖析,以期深入认识边缘海的再矿化作用及其对边缘海碳汇的影响。  相似文献   

蒙脱石、高岭石和伊利石X射线衍射定量分析     

王琦  马龙  黄康俊  雷志远  谢淑云 《贵州地质》2021,38(1):71-78

黏土矿物的组成和含量变化与其形成时的气候、环境密切相关,是重建古环境演化的有效代用指标,因此黏土矿物定性尤其是定量分析显得尤为重要.然而,常用的定量分析方法不能直接应用,且定量分析软件在使用过程中存在误差传导效应.为此,本研究基于X射线衍射分析,针对常见的黏土矿物(蒙脱石、高岭石和伊利石),建立了两种简便的定量分析方法...  相似文献