Tectonomagmatic origin of Precambrian rocks of Mexico and Argentina inferred from multi-dimensional discriminant-function based discrimination diagrams |
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| Institution: | 1. Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile;2. ARC Centre of Excellence in Ore Deposits, School of Earth Sciences, University of Tasmania, Hobart, Australia;3. Departamento de Matemáticas, Universidad Católica del Norte, Antofagasta, Chile;1. Instituto de Geociências, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil;2. Universidade Estadual do Rio Grande do Sul, 90010-191 Porto Alegre, RS, Brazil;3. Instituto de Geociências, Universidade Federal do Rio de Janeiro, 21949-900 Rio de Janeiro, RJ, Brazil;1. Departamento de Geologia, Universidade Federal do Espírito Santo, Alto Universitário, s/n, Alegre 29500-000, ES, Brazil;2. Departamento de Geologia, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, s/n, Ouro Preto 35400-000, MG, Brazil;3. Retired by IRD (Institut de recherche pour le développement), France;1. XR-GEOMAP, R. Durand Av. N 397, Grand Bourg, Salta, Argentina;2. Universidad Nacional de Río Negro, Av. Roca 1242, 8332 General Roca, Río Negro, Argentina;3. University of Saskatchewan, Department of Geological Sciences, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada;4. Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina;1. Department of Geology, University of Delhi, Delhi, India;2. Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima, Japan |
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| Abstract: | Several new multi-dimensional tectonomagmatic discrimination diagrams employing log-ratio variables of chemical elements and probability based procedure have been developed during the last 10 years for basic-ultrabasic, intermediate and acid igneous rocks. There are numerous studies on extensive evaluations of these newly developed diagrams which have indicated their successful application to know the original tectonic setting of younger and older as well as sea-water and hydrothermally altered volcanic rocks. In the present study, these diagrams were applied to Precambrian rocks of Mexico (southern and north-eastern) and Argentina. The study indicated the original tectonic setting of Precambrian rocks from the Oaxaca Complex of southern Mexico as follows: (1) dominant rift (within-plate) setting for rocks of 1117–988 Ma age; (2) dominant rift and less-dominant arc setting for rocks of 1157–1130 Ma age; and (3) a combined tectonic setting of collision and rift for Etla Granitoid Pluton (917 Ma age). The diagrams have indicated the original tectonic setting of the Precambrian rocks from the north-eastern Mexico as: (1) a dominant arc tectonic setting for the rocks of 988 Ma age; and (2) an arc and collision setting for the rocks of 1200–1157 Ma age. Similarly, the diagrams have indicated the dominant original tectonic setting for the Precambrian rocks from Argentina as: (1) with-in plate (continental rift-ocean island) and continental rift (CR) setting for the rocks of 800 Ma and 845 Ma age, respectively; and (2) an arc setting for the rocks of 1174–1169 Ma and of 1212–1188 Ma age. The inferred tectonic setting for these Precambrian rocks are, in general, in accordance to the tectonic setting reported in the literature, though there are some inconsistence inference of tectonic settings by some of the diagrams. The present study confirms the importance of these newly developed discriminant-function based diagrams in inferring the original tectonic setting of Precambrian rocks. |
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| Keywords: | Tectonomagmatic diagrams Tectonic setting Arc Rifting Collision Within-plate |
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