Abstract

TORO TORO, Luz Mary; HINCAPIE JARAMILLO, Gustavo  and  OSSA MEZA, César Augusto. PETROLOGY AND GEOCHEMISTRY OF THE METAGABBRO OF RIO OLIVARES NNW SECTOR OF MANIZALES (CALDAS). bol.geol. [online]. 2010, vol.32, n.2, pp.73-84. ISSN 0120-0283.

The Río Olivares Metagabbro is a body of igneous intrusive rocks that outcrops along the Río Olivares at N-NW of the Manizales city (department of Caldas, Colombia). This igneous body is defined by series of centimeter to metric-sized faulted slivers within the western sector of Quebradagrande Complex. Petrographic analyses show rocks with cumulus and isotropic gabbroic textures. The primary minerals are: calcium plagioclase and clinopyroxene, secondary minerals are: amphibole, chlorite, epidote, plagioclase and less quartz, carbonate and occasionally opaque minerals. According to geochemical distribution of major elements, those rocks were generated from fractional crystallization of unique magma showing a typical tendency of tholeiitic series. Taking into account the behavior of trace elements in geotectonic discrimination diagrams, they were generated in an ocean floor setting and their sources coming from an N-MORB segment in the upper mantle. REE patterns normalized with respect to chondrite, show relatively homogeneous patterns, flats and enriched up to 10 times compared to the typical N-MORB. These rocks are part of the oceanic basement of the Early Cretaceous Quebradagrande Complex, and they are affected by mylonitization and ocean floor metamorphism.

Keywords : Manizales; metagabbros; N-MORB.

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