Past and current geochemical conditions influence silicon isotope signatures of pedogenic clay minerals at the soil profile scale, Ethiopia
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چکیده
منابع مشابه
construction and validation of the translation teacher competency test and the scale of students’ perceptions of translation teachers
the major purpose of this study was to develop the translation teacher competency test (ttct) and examine its construct and predictive validity. the present study was conducted in two phases: a qualitative phase as well as a quantitative phase. in the first phase of the study, the author attempted to find out the major areas of competency required for an academic translation teacher. the second...
Thermodynamics of Clay Minerals on Mars: Insight into the Geochemical Environment of Early Mars
Introduction: The Mars Express OMEGA imaging spectrometer recently identified clay minerals (nontronite and montmorillonite) in several outcrops of Noachian age [1]. Clay minerals usually result from long term alteration of primary minerals by liquid water and on Earth are usually the products of weathering processes. The presence of clay minerals suggests a primary environment completely diffe...
متن کاملCalculation of site-specific carbon-isotope fractionation in pedogenic oxide minerals.
Ab initio molecular dynamics and quantum chemistry techniques are used to calculate the structure, vibrational frequencies, and carbon-isotope fractionation factors of the carbon dioxide component [CO(2)(m)] of soil (oxy)hydroxide minerals goethite, diaspore, and gibbsite. We have identified two possible pathways of incorporation of CO(2)(m) into (oxy)hydroxide crystal structures: one in which ...
متن کاملClay Minerals and Catalysis
More than half a century ago, Irish physicist John Desmond Bernal and Swiss geochemist Victor M. Goldschmidt independently proposed that clay minerals may have played an important role in prebiotic synthesis (Bernal 1949; Goldschmidt 1952). I concur that mineral catalysis must have had a central role in prebiotic synthesis because most uncatalyzed reactions start from simple precursors like hyd...
متن کاملThe origin and formation of clay minerals in soils" past, present and future perspectives
It has long been recognized that the minerals in the clay (<2 gm) fractions of soils play a crucial role in determining their major physical and chemical properties, and inevitably, questions concerning the origin and formation of these minerals have assumed some prominence in soil science research. This review considers some important aspects of these questions and is confined to clay minerals...
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ژورنال
عنوان ژورنال: Chemical Geology
سال: 2019
ISSN: 0009-2541
DOI: 10.1016/j.chemgeo.2019.06.013