Abstract

GONZALEZ-PRECIADO, Angélica Julieth; DURAN-GONZALEZ, Sofía  and  MARINO-MARTINEZ, Jorge Eliecer. Hydrothermal evidence in igneous intrusions in Pajarito, on the East flank of the Eastern Cordillera (Colombia). Bol. geol. [online]. 2021, vol.43, n.3, pp.87-105.  Epub Apr 01, 2022. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v43n3-2021004.

In the locality of Pajarito (Boyacá Department - Colombia), in an area of 48 km2 and on the eastern flank of the Eastern Cordillera, a series of mafic intrusive bodies emerge, that are regionally oriented in a NS direction and are hosted in sedimentary rocks of Lower Cretaceous age. Six intrusions were studied of these bodies: five laminar bodies, defined as Intrusion 1 to Intrusion 5, and a sixth larger body defined as Main Igneous Body or ‘CIP’ (by its acronym in Spanish). These rocks are dominated by phaneritic to porphyritic textures, with crystals of: pyroxene and plagioclase, and are found intruding pelites that, in the area of contact with the intrusives, vary to metalimolites and argillites. The field and petrographic data suggest that these intrusions were altered by the action of hydrothermal solutions that generated as a consequence of chemical exchange, replacement textures and two paragenetic associations: the sericite - pyrite - calcite paragenesis, related to a pH between neutral to slightly acid; and calcite - chlorite - epidote - actinolite paragenesis associated with areas of neutral to basic pH. Similarly, hydrothermal solutions could be related to a hypothetical mineralization, as a product of the process of leaching and enrichment of metallic elements from their passage through igneous bodies, and their consequent precipitation in a geochemical trap.

Keywords : Petrography; Hydrothermal alteration; Intrusions; Igneous body; Pajarito.

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