منابع مشابه
Geochemistry and dynamics of calcrete genesis in semi-arid regions
Calcretes are the calcite crusts widely developed at the Earth's surface in semi-arid regions (e.g., Goudie, 1983; Nahon, 1991; Wright and Tucker, 1991 ). Thickness of calcretes is tens of centimeters to a few meters, and increases downslope. Calcretes pseudomorphically replace all underlying silicate rocks. Parent rock structure and bulk volume are preserved. In the lower part of calcrete prof...
متن کاملSources of strontium and calcium in desert soil and calcrete
The carbon-cycle significance of soil carbonate fluxes is subject to large uncertainties because it is not clear precisely how much calcium is derived from atmospheric sources compared with that from the chemical weathering of silicate minerals. In the petrocalcic horizon (calcrete) of a Pleistocene soil from the USDA–SCS Desert Project area near Las Cruces, NM, approximately 1.5 g Ca=cm3 has b...
متن کاملModes of Speciation in Subterranean Diving Beetles from a Single Calcrete Aquifer in Central Western Australia
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متن کاملFan-surface dynamics and biogenic calcrete development: Interactions during ultimate phases of fan evolution in the semiarid SE Spain (Murcia)
Pleistocene alluvial fan surfaces of the Campo de Cartagena-Mar Menor Basin (Murcia, SE Spain) are capped by thick mature calcretes. Calcrete profiles consist mainly of six different horizons: prismatic, chalky, nodular, massive, laminar and coated-gravels. Petrographic study of the calcretes has shown the occurrence of features such as alveolar septal structures, calcified filaments, coated gr...
متن کاملInvestigation of blind massive sulphide deposit signatures in the calcrete layers as a geochemical barrier: A case study of Areachap, Kantienpan and Copperton deposits
The trace element contents on the surface originated from mineralization would depend to the thickness of the calcrete layer above the ore deposit on the surface. A very thick layer of calcrete may not allow for much dispersion of the elements of interest in the surface. These elements may be concentrated in non-magnetic and magnetic part of calcrete. Based on the current research, mineralogica...
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ژورنال
عنوان ژورنال: Geological Magazine
سال: 1902
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800181646