INVESTIGADORES
GREGORI Daniel Alfredo
artículos
Título:
New Evidence on the Nature of the Frontal Cordillera Ophiolitic Belt- Argentina
Autor/es:
DANIEL ALFREDO GREGORI; BJERG, E.
Revista:
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: New York; Año: 1997 vol. 10 p. 147 - 155
ISSN:
0895-9811
Resumen:
New petrographic and chemical data of volcanic rocks from the Metales
Belt, Rio de las Tunas area, in the Frontal Cordillera of Argentina are
presented. The rocks display a broadly basaltic composition. Two
varieties of basaltic dikes can be differentiated. One group, whose
mineralogy comprise essentially tremolite-actinolite, plagioclase,
pyroxene and limited amounts of olivine as the main phases, display
metamorphic textures. The other group show porphyritic textures
consisting of zoned plagioclase and K-feldspar. Zoned orthopyroxenes are
scarce. Chemically, the rocks are similar to the Caradocian basaltic
rocks (the ofiolitas famatinianas) from the Precordillera, San Juan
Province. REE chondrite-normalised patterns and overall abundances,
along with other petrologic and geochemical similarities, suggest a
common mode of origin for both groups of basaltic rocks. Their
geochemical and petrographical characateristics are consistent with a
continental-scale extension environment during Eopalaeozoic times that
could include an oceanic rift in an early stage of development, a
transitional ridge segment or oceanic intraplate magmas, similar to
those erupted in oceanic islands