INVESTIGADORES
ARIZA Juan Pablo
artículos
Título:
The E-MORB like geochemical features of the Early Paleozoic mafic-ultramafic belt of the Cuyania terrane, western Argentina
Autor/es:
FLORENCIA BOEDO; GRACIELA VUJOVICH; SUSANNE KAY; JUAN ARIZA; SOFIA PEREZ
Revista:
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2013 vol. 48 p. 73 - 84
ISSN:
0895-9811
Resumen:
The Argentine Precordillera is located in the central western region of Argentina, within the Central
Andes. Throughout its westernmost sector, mafic and ultramafic bodies including serpentinites, mafic
granulites, basaltic dikes/sills and pillow lavas are associated with metasedimentary rocks deposited in a
deep marine and slope environment. These magmatic units, which are known as the Precordillera
ultramafic-mafic belt, are considered to have a range of Early Paleozoic age based on published UePb
zircon ages and fossil fauna. The entire sequence shows the effects of complex polyphase Paleozoic
deformation and was subjected to a low grade metamorphism considered to be of middle-late Devonian
age. The chemistry of the Peñasco and Cortaderas mafic dikes and sills in the southern part of this belt,
which are largely plagioclase þ clinopyroxene-bearing tholeiitic basalts, is the focus of this study. These
volcanic rocks all have E-MORB-like major and trace element and εNd (þ6.0 to þ9.3) signatures with
similarities to those previously reported throughout the belt. The new descriptions and major and traceelement
analyses presented here confirm the similarity of the E-MORB-like chemistry of the Early
Paleozoic mafic rocks along the entire belt, which spans some 500 km in length. There is a general
consensus that these units are exposed as a consequence of the collision of the Chilenia terrane against
the Gondwana margin during the middle to late Devonian, but the details of timing, the origins of the
continental blocks and the nature of the collision are still debated. The results presented support the
western Precordillera basaltic dikes/sills as having formed in the early stages of oceanic rifting along the
Gondwana (Precordillera) continental margin with their E-MORB-like character reflecting mixing of
depleted and enriched mantle and continental lithospheric sources.