In this paper, a set of physical, geochemical and mineralogical indicators are proposed for the correlation of soil age. The parameters studied allowed the highlighting of trends in soil aging as well as the relating of these trends to specific soil forming processes. Soil aging was marked by a progressive increase in clay content and a decrease in silt/clay ratio, a slight reduction in the CEC...

INTRODUCTION Polymer/clay nanocomposites, in which nanosized silicate plates of clay are uniformly dispersed in the polymer matrix, provide enhanced mechanical and thermal properties compared to conventional composites. Not all polymer and clay combinations will form nanocomposites: the compatibility and interfacial properties between polymer matrix and clay layers significantly influence the e...

Abstraet--A method for the determination of the cations of Na, K, Mg and Ca adsorbed on clay minerals mixed with CaCO3 and MgCO3 is described. An ethanolic solution of LiC1-CsC1 is used to displace the exchangeable cations. Blank determinations performed using either a second ethanolic leach or a second LiC1-CsC1 leach, are used to correct for carbonate dissolution. Details of the methods devel...

Northwest Africa (NWA) 5790 is the most recently discovered member of the nakhlite group. Its mineralogy differs from the other nakhlites with a high abundance mesostasis (38.1 3.6 vol%) and scarcity of olivine (4.0 2.2 vol%). Furthermore, zoning of augite phenocrysts, and other petrographic and chemical characteristics suggest that NWA 5790 samples the chilled margin of its parent lava flow/si...

To assess the environmental perturbation induced by the impact event that marks the Cretaceous–Tertiary (K–T) boundary, concentrations and isotopic compositions of bulk organic carbon were determined in sedimentary rocks that span the terrestrial K–T boundary at DogieCreek,Montana, and Brownie Butte,Wyoming in theWestern Interior of the United States. The boundary clays at both sites are not bo...

[1] The carbonate saturation profile of the oceans shoaled markedly during a transient global warming event known as the Paleocene-Eocene thermal maximum (PETM) (circa 55 Ma). The rapid release of large quantities of carbon into the ocean-atmosphere system is believed to have triggered this intense episode of dissolution along with a negative carbon isotope excursion (CIE). The brevity (120–220...

We conducted a modified Bureau Commun Reference (BCR) sequential extraction on a basaltic soil (phono-tephrite) from Mt. Meru in Northern Tanzania in order to determine the relative contribution of water soluble, carbonate and exchangeable, oxide and organic fractions to the bulk composition of the soil. Elemental compositions were determined by ICP-MS and corrected for loss on ignition. Relati...

the micromorphology of pedogenic carbonate features in calcareous soils of arid and semiarid regions of kohgilouye province, southwestern iran, has been studied to determine their genesis and distribution in different climatic regions. eight representative pedons (from a total number of 24 pedons) were studied in aridic-ustic (minimum rainfall), ustic and xeric (maximum rainfall) soil moisture ...

the effect of 0, 2, and 5 mm of citric, malic and oxalic acids on phosphorus (p) sorption was evaluated. in the collected soils, the level of total calcium carbonate stood in the range of 4-28%, clay content at 33-56% and the amount of organic matter recorded within 0.6-2.7%. the results indicated that the addition of organic acids causes reduction in p sorption. citric acid in most soils, was ...