Geochemistry and Biomarker Analysis of the Bentonites from Esquivias (Toledo, Spain)



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García-Rivas, Javier and Suárez, Mercedes and Torres, Trinidad and Sánchez-Palencia, Yolanda and García Romero, Emilia and Ortiz, J.E. (2018) Geochemistry and Biomarker Analysis of the Bentonites from Esquivias (Toledo, Spain). Minerals, 8 (7). p. 291. ISSN 2075-163X

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The Tajo Basin is one of the richest in Mg-clays known around the world. Mg-bentonites, kwon as pink clays and green clays, alter in the Intermediate Unit of the Miocene sediments. In this work, a new approach to the genesis of these bentonites is performed by studying for the first time the biomarkers present in these clays in relation to the mineralogy and geochemistry, as well as using discriminatory criteria between green and pink clays. Samples were collected at a quarry of Mg-bentonites, in the proximities of Esquivias (Toledo, Spain). Mineralogical characterization and semi-quantification (X-ray diffraction (XRD)) allowed a well-defined classification according to the mineralogical content of the samples to be established, differentiating four associations. Geochemical analyses are clearly linked to the mineralogy and provide criteria to differentiate the genesis of the materials studied. In this regard, green clays are interpreted as having a more detrital character than pink clays, which present a more authigenic character. Biomarkers (n-alkanes and n-alkanoic acids) were studied, not showing a clear link with the mineralogy as in the case of the geochemistry, but providing interesting information about the origin and degradation of the organic matter. Pink clays have higher contents in biomarkers than green clays, providing a discriminative criterion.

Item Type:Article
Uncontrolled Keywords:bentonite; saponite; authigenic clays; geochemistry; biomarker analysis
Subjects:Sciences > Geology > Soil science
Sciences > Geology > Geochemistry
Sciences > Geology > Mineralogy
ID Code:49848
Deposited On:30 Oct 2018 17:28
Last Modified:11 Dec 2018 08:46

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