Consulta: subjectFacets:"Chemical weathering"
Registros recuperados: 4
Data/hora: 27/07/2024 02:02:08

Climatic and tectonic controls on weathering in south China and Indochina Peninsula: Clay mineralogical and geochemical investigations from the Pearl, Red, and Mekong drainage basins
Provedor de dados: 5
Autores: Liu, Zhifei; Colin, Christophe; Huang, Wei; Le, Khanh Phon; Tong, Shengqi; Chen, Zhong; Trentesaux, Alain.
Results of clay mineralogy, major element geochemistry, and Sr and Nd isotopes in 93 argillaceous samples collected from drainage basins of the Pearl, Red, and Mekong rivers reveal different degrees of chemical weathering in Southeast Asia despite similar climate conditions across these regions. The kaolinite/illite ratio, illite chemistry index, and illite crystallinity can be used as indicators of chemical weathering intensity. These mineralogical proxies combined with the K(2)O/(Na(2)O + CaO) molar ratio, chemical index of alteration (CIA), and weathering trends observed from major element results indicate intensive silicate weathering in the Pearl River basin, moderate to intensive in the Mekong River basin, and moderate in the Red River basin....
Tipo: Text
Palavras-chave: Clay minerals; Major elements; Chemical weathering; Pearl River; Red River; Mekong River.
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00235/34613/32949.pdf

Link between Indian monsoon rainfall and physical erosion in the Himalayan system during the Holocene
Provedor de dados: 5
Autores: Joussain, Ronan; Liu, Zhifei; Colin, Christophe; Duchamp-alphonse, Stephanie; Yu, Zhaojie; Moreno, Eva; Fournier, Lea; Zaragosi, Sebastien; Dapoigny, Arnaud; Meynadier, Laure; Bassinot, Franck.
Mineralogical and geochemical analyses conducted on cores located on the active channel-levee system of the northern Bengal Fan are used to establish changes in the weathering pattern and the sediment transport of the Himalayan system, and evaluate the effect of Indian summer monsoon rainfall during the Holocene. Our data indicate that during the Holocene, sediments from the northern Bengal Fan originate mainly from the G-B river system without any significant changes in the relative contribution of these rivers. From 9.8 to around 6 ka, relatively low smectite/(illite+chlorite) ratios and relatively high K/Si* ratios indicate high physical denudation rates of the Himalayan highlands together with a rapid transfer of the detrital material to the Bengal...
Tipo: Text
Palavras-chave: Bengal Fan; Chemical weathering; Sr and Nd isotopic compositions; Physical erosion; Clay mineralogy.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00393/50416/51143.pdf

Sedimentation and pedogenic features in a clay deposit in Quadrilátero Ferrífero, Minas Gerais, Brazil
Provedor de dados: 42
Autores: Santos,Maria-do-Carmo; Varajão,Angélica F.D.C.
The clay deposit of Caxambu Hill occurs in a NW/SE oriented graben originated by syntectonic sedimentation during Cenozoic. Four facies were identified (fragmentary, nodular, massive and friable) and their differentiation is related to gravity mass-flow processes. The fragmentary facies is composed of extraclast fragments of the local Paleoproterozoic basement and sand size quartz-grains dispersed in a kaolinite-muscovite-goethitehematite matrix. The nodular facies is constituted by lithorelictal and pedorelictal nodules dispersed in a similar matrix as in the fragmentary facies. The massive facies is characterized by quartz grains dispersed in a kaolinite, hematite and goethite matrix with minor amounts of muscovite. The friable facies differs from the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Kaolinite; Lithofacies; Micromorphology; Gravity mass flow; Chemical weathering.
Ano: 2004
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652004000100013

Some topics on geochemistry of weathering: a review
Provedor de dados: 42
Autores: Formoso,Milton L.L.
Weathering is a complex process comprising physical disaggregation, chemical and biological decomposition of rocks and minerals transforming complex structure minerals in simpler ones. Hydrolysis of silicates is perhaps the most important process but associated certainly to biological weathering. It is discussed the role ofwaters: activities/concentrations of chemical species, pH, Eh, importance of complexes. Weathering is not only a destructive process. It can concentrate chemical species and form mineral deposits (kaolin, bauxite, Fe, Mn, P, Nb, Au). Weathering studies are important in pedology, engineering geology, hydrogeology, paleoclimatology and ecology. The use of stonemeal is based upon the study of rock weathering.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Chemical weathering; Hydrolysis of silicates; Biological weathering; Physicochemical parameters of weathering.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652006000400014