Abstract

MORENO SANCHEZ, Mario; GOMEZ CRUZ, Arley de Jesús  and  CASTILLO GONZALEZ, Hardany. PALAEOZOIC'S FOSSILS IN THE NORTHERN OF THE CORDILLERA CENTRAL AND DISCUSSION ABOUT GEOLOGIC SIGNIFICANCE. Bol. cienc. tierra [online]. 2008, n.22, pp.39-47. ISSN 0120-3630.

The age and origin of metamorphic core of the Central Mountain Chain (Cajamarca Complex, sensu lato) remain like one of the great riddles of the Colombian Geology. The isotopic data available show a wide dispersion between the ages of Neoproterozoic and early Mesozoic, in contrast to the age predevonian of metamorphic basement of the Eastern Mountain Chain and Precambrian of some sectors upper Magdalena valley. Although it has been suggested that this block is from exotic origin, the diversity of rocks and their difficult structural relationships have prevented build a sound geological history with the evolution of structural contiguous blocks. The available biostratigraphical data are low or they are not much broadcasted. Here is made a brief account of some fossiliferous localities located at east of the north part of the Central Mountain Chain. We emphasize occurrences of lowgrade metamorphism in sequences of rocks situated between Rovira (Tolima) and San Carlos (Antioquia). Palynomorphs of Devonian age are reported for the Amoyá Formation (near Ortega, Tolima), Crinoids of Carbonífera age (?) in the crystalline limestone of Cajamarca Complex (near Ibague), and a remainder of a possible fish found in quartzite Cajamarca Complex near San Carlos (Antioquia). In addition, there is information still unconfirmed about fossils of early Paleozoic age in rocks of very low degree of metamorphism in Santa Teresa (Tolima) and Aquitania (Antioquia). The data suggest that the basement of the Central Mountain Chain at east of the OtúPericos fault has more affinity with the land of Central Mountain Chain and Magdalena valley.

Keywords : Mountain range central; Palaeozoic; Colombia.

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