Per citar aquest document: http://ddd.uab.cat/record/86048
Chemostratigraphy of the Pliensbachian, Puesto Araya Formation (Neuquén Basin, Argentina)
Valencio, S.A. (Instituto de Geocronología y Geología Isotópica (INGEIS))
Cagnoni, M.C. (Instituto de Geocronología y Geología Isotópica (INGEIS))
Ramos, A.M. (Instituto de Geocronología y Geología Isotópica (INGEIS))
Riccardi, A.C. (Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo)
Panarello, H.O. (Instituto de Geocronología y Geología Isotópica (INGEIS))

Data: 2005
Resum: In a preliminary attempt to establish an isotope stratigraphy, strontium, carbon and oxygen isotope ratios were determined from marine biogenic carbonates of Pliensbachian age, in the context of scheme of local ammonite Zones correlatable to the European Standard Zonation. Two sections, rio Atuel and arroyo Serrucho, of the mainly siliciclastic Puesto Araya Formation, Neuquen Basin, south-western Mendoza, Argentina, were studied. Specimens of the bivalve genera Weyla Bhom and Gryphaea Lamarck were selected for the isotopic determinations because of their low-Mg calcite original mineralogy and widespread presence. Scanning electron microscopy, X-ray diffraction and X-ray fluorescence spectrometry techniques were used to control the good degree of preservation of most of the biogenic material, as evidenced by pristine fabrics, 100% calcite composition and Sr, Mn and Fe concentrations. Although strontium isotope ratios are slightly scattered, it is possible to compare them with those of the Early Jurassic seawater reference curve. Carbon isotope signals show two relative maxima, correlatable with those recorded for the upper part of the Ibex Zone and the middle part of the Margaritatus Zone in various European sections, indicating the possible global significance of these events. d18O values were found to be unreliable for isotope stratigraphy, as they are largely depleted in comparison to those of coeval unaltered marine carbonates.
Drets: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l’obra i la creació d’obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l’obra original i es reconegui l’autoria de l’obra original. Creative Commons
Llengua: Anglès.
Document: article ; recerca ; publishedVersion
Matèria: Chemostratigraphy ; Ammonite Zonation ; Bivalve shells ; Pliensbachian
Publicat a: Geologica acta, Vol. 3, Núm. 2 (2005) , p. 147-154, ISSN 1696-5728

Adreça alternativa: http://www.raco.cat/index.php/GeologicaActa/article/view/82369
DOI: 10.1344/105.000001403


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