نتایج جستجو برای: calcic horizons and thus
تعداد نتایج: 16834445 فیلتر نتایج به سال:
Understanding the development of calcic and petrocalcic horizons is important for palaeoclimate reconstruction. The micromorphology and geochemistry of Quaternary calcic and petrocalcic horizons formed in the area around Coimbatore, Tamil Nadu are discussed. The calcic horizons represent the Bk horizons that occur as thick complex profiles ( 300 cm thick) in the foothill regions while the lamin...
Recent studies of soil–landscape relationships in northeastern Patagonia identified fibrous-clay minerals in calcic and petrocalcic horizons developed on old fluvio-glacial plains called “Rodados Patagónicos” (RP). The objectives of this study were: i) to evaluate the occurrence of fibrous-clay minerals in the arid soil environment, and ii) to establish the relationship between the soil propert...
Clay mineralogy of paleosols provides more information about Quaternary climatic changes and paleoenvironmental conditions. Clay minerals of an alluvial fan in eastern Isfahan were studied, using x-ray diffraction analysis. Studied paleosols are located on old Qf1 and Qf2 geomorphic surfaces. Qf1 geomorphic surface is older and topographically higher than Qf2. The results of clay mineralogy sho...
The chemical, morphological and mineralogical properties of two Enon sandy loam (fine, mixed, thermic Ultic Hapludalfs) soilsaprolite profiles, one formed on gabbro and the other on metagabbro, are compared. Clay skins are scarce and stress cutans common in the argillic horizons of these soils. Iron-manganese concretions are concentrated in soil horizons immediately above the argillic horizons....
in this study argillic horizons in calcareous soils of a semiarid region, with xeric and mesic soil moisture and temperature regimes, in the west of urmia lake were studied. thus, a toposequence in different physiographic positions including piedmont plains, plateau, hills and mountains was investigated. in each land type, three soil profiles were dug and described and their morphological prope...
Although various episodes of wet Quaternary climates have been suggested in studies of the Negev Desert, here we demonstrate that Reg soils, developed on flat alluvial surfaces and sensitive to minor changes in precipitation, indicate that the southern Negev has been permanently hyperarid at least since the middle Pleistocene. The wetter episodes were restricted to the northern Negev, currently...
The rarity of Devonian tetrapods and the absence of tetrapods during the first 14 million years of the Mississippian (Romer’s Gap) have inspired hypotheses of fish-tetrapod evolutionary transition as an escape from difficult habitats such as deserts or stagnant waters. These hypotheses and Romer’s Gap are tested here using depth to calcic horizon in paleosols of the northern Appalachians as a p...
soils of the arid–semiarid karaj basin in north-central iran have formed on alluvium-colluvium derived from mixed calcareous-gypsiferous marls of miocene and basic igneous rocks of holocene age. in order to characterize and classify the soils and to determine the soil-landscape relationship in the area, sixteen pedons located on different physiographic positions have been described, sampled and...
Comparing the ability of ST and WRB systems to describe soils with clay-enriched horizons was the aim of the present research. In arid and semi-arid regions of Iran, two study sites were considered. Three pedons at each study site were selected, described and sampled. Soils were classified based on ST (2014) and WRB (2015) systems. The micro-morphological investigations were done to confir...
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