Keywords
El Vapor creek
mylonitic rocks
Grenvillian orogeny
Colombia
How to Cite
Abstract
In the El Vapor creek (Puerto Berrio-Antioquia), mylonitic rocks were identified. The geochemical data for the mylonites revea] high SiO2 content (65.7 to 80.9 wt %) and a peraluminous character. A Rb-Sr isochron for these mylonites yielded an age of 894 ± 36 Ma, with an initial 87Sr/86Sr ratio of ca. 0.71785. This date is interpreted here as a metamorphic resetting age in response to the Grenvillian orogeny. The high initial ratio suggests a long crustal residence period. This interpretation is confirmed with TDM model a ges of 1757 and 1829 Ma and zircon evaporation age of 1.1 Ga.
References
Alvarez, J. 1981. Determinación de edad Rb/Sr en rocas del Macizo de Garzón. Cordillera Oriental de Colombia. Geología Norandina. Bogotá, 4: 31-38.
Alvarez, J. & Linares, E. 1984. Una edad K/Ar del Macizo de Garzón. departamento del Huila (Colombia). Geología Norandina, Bogotá. 9: 31-38.
Botero A. G. 1940. Geología sobre el Ordoviciano de Antioquia. Mineria, Medellín, 17(99): 8249-8256.
Bell, T. & Hammond, R. L. 1984. On the internal geometry of mylonite zones. Journal of Geology, 92: 667-686.
DePaolo, D. J. 1981. Neodymium isotopes in The Colorado Front Range and crust-mantle evolution in the Proterozoic, Nature. 291:193-196.
DePaolo, D. J. & Wasserburg, G. J. 1976. Nd isotopic variations and petrogenetic models, Geophysical Research Letters, 3(5): 249-252.
Feininger, T. 1970. The Palestina fault. Geological Society of American Bulletin, 81(4): 1201-1216.
Feininger, T., Barrero, D. & Castro, N. 1972. Geología de parte de los departamentos de Antioquia y Caldas (Sub-zona II-B). Boletín Geológico, Bogotá. 20(2):1-173.
Harrison, J. V. 1930. The Magdalena Valley. C.R. 15th International Geological Congress, Petroria, South Africa, 2: 399-409.
Kober B. 1986. Whole-grain evaporation for 207Pb/Pb-age-investigations on single zircons using a double-filament thermal ion source. Contributions to Mineralogy and Petrology, 93: 482-490.
Kroonenberg, S. B. 1982. A grenvillian granulite belt in the Colombian Andes and its relation to the Guiana Shield. Geol. Mijnbouw, 61:325-333.
MacDonald, W. D. & Hurley, P. M. 1969. Precambrian gneisses from northern Colombia, South America. Geological Society of America Bulletin, 80: 1867-1872.
Maniar, P. D. & Piccoli, P. M. 1989. Tectonic discrimination of Granitoids. Geological Society of America Bulletin. 101: 635-643.
O'Connor, J. T. 1965. A classification of quartz-rich igneous rocks based on feldspar ratios. U. S. Geological Survey special Paper. 525B: 79-84.
Ordóñez, C. O. 1997. O Pré-Cambriano na parte norte da Cordilheira Central dos Andes colombianos (Dissertação de Mestrado). Universidade de Brasília, Instituto de Geociências. Brasília-Bra- sil, 99p.
Ordóñez, C. O., Pimentel, M. M., Moraes, R., Viana, M., Angel, P. & Restrepo, J. J. 1996. Ocurrencia de rocas cizalladas en la región de Puerto Berrio - Antioquia. - VII Congreso Colombiano de Gen- logía, Libro de resúmenes, Bogotá.
Priem, H. N. A., Kroonenberg, S. B., Boelrijk, N. A. 1. M., & Hebeda, E. H. 1989. Rb-Sr and K-Ar evidence for the presence of a 1.6 Gabasement underlying the 1.2 Ga Garzón-Santa Marta granulite belt in the Colombia Andes. Precambrian Research, 42: 315-324.
Restrepo, J. J. & Toussaint, J. F. 1988 Terranes and continental accretion in the Colombian Andes. Episodes, 11(3): 189-193.
Restrepo-Pace, P. A., Ruiz J., Gehrels, G. & Cosca, M. 1997. Geochronological and Nd isotopic data of Grenville-age rocks in the Colombian Andes: new constraints for Late Proterozoic-Early Paleozoic paleocontinental reconstructions of the Americas. Earth and Planetary Science Letters, 150: 427-441.
Ruiz, J., Patchett, J. P. & Ortega, F. G. 1988. Proterozoic and Phanerozoic basement terranes of Mexico from Nd isotopes studies. Geological Society of America Bulletin, 100: 274-281.
Steiger, R. H. & Jäger, E. 1977. Subcomission on gechronology: conven- tion on the use of decay constaints in geo and cosmochronology. Earth and Planetary Sciences Letters, 36: 359-362.
Toussaint, J. F. & Restrepo J. J. 1994. The Colombian Andes during Cretaceous times. In: Cretaceous tectonics of the Andes. Ed. Vieweg & Sohn. Wiesbaden: 61-100.
Tschanz, C., Marvin, R., Cruz, J., Mehnert, H. & Cebula, G. 1974, Geologic evolution of the Sierra Nevada de Santa Marta, Northeastern Colombia. Geological Society of America Bulletin, 87: 481-495.
Vesga, C. J. & Barrero D. 1978. Edades K/Ar en rocas igneas y metamórficas de la Cordillera Central de Colombia y su implicación geológica. II Congreso Colombiano de Geológia, libro de resúmenes, Bogotá.
Ward, E. D., Goldsmith, R., Cruz, B. J. & Restrepo, A. H. 1973. Geología de los cuadrangulos H-12 Bucaramanga y H-13 Pamplona. Boletín Geológico, Bogotá, 21(1-3): 1-132.
Wise, D. U., Dunn, D. E., Engelder, J. T., Geiser, P. A., Hatcher. R. D., Kish, S. A., Odom, A., L. & Schamel, S. (1984). Fault-related rocks:suggestions for terminology. Geology, 12: 391-394.
Yañez, P., Ruiz, J., Patchett, J. P., Ortega, F. G. & Gehrels, G. 1991. Isotopic studies of the Acatlan Complex, southern Mexico: implications for Paleozoic north america tectonics. Geological Society of America Bulletin, 103: 817-828.
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