Abstract

MANOSALVA-SANCHEZ, Sandra Rocío et al. PETROGENETIC STUDY of METAMORPHIC ROCKS OF THE FLORESTA MASSIF, EASTERN CORDILLERA, COLOMBIAN ANDES. bol.geol. [online]. 2017, vol.39, n.1, pp.83-103. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v39n1-2017004.

In the Eastern Cordillera of Colombia a series of ancient massifs of metamorphic rocks of Precambrian-Paleozoic age occur, which from south to north are: Garzón, Quetame, Floresta and Santander, whose study and geological understanding constitutes an essential part of the geological evolution of Colombia. The core of the Floresta Massif consists of metamorphic rocks (Busbanzá´s Phyllites and Schists Formation) of pelitic and semipelitic protoliths of pre-Ordovician age, which were affected by a first event of regional orogenic metamorphism average P/T (Pressure/Temperature), where phyllites, schists and paraneis were developed, from the greenschist facies to the amphibolite facies and the Ordovician (471±22 Ma) for a second event of contact metamorphism, related to a series of granitic intrusions syntectonic (Otengá Stock), which developed hornfels, pyroxene facies hornfelsa. Floresta Massif forms an anticlinal structure, buzante to the southwest and elongated north, extending towards the Massif de Santander, which is limited laterally by the Boyacá and Soapaga fault systems to the northwest and southeast, respectively. The igneous and metamorphic core is highly eroded in the central part and is unconformably covered on its edges by conglomerates, sandstones and mudstones from Devonian to Cretaceous age. Studies by several authors always relate the occurrence of cordierite in the metapelitic units; however, in this study, the analisis of mineral chemistry (WDX) by electron microprobe reveals that what was being defined as cordierite corresponds to orthoclases associated with albites (pertitic textures), thus changing both the mineral assemblages and the conditions of metamorphism.

Keywords : Metapelites; metamorphism; Busbanzá Phyllites and Schists; Floresta Massif; Colombia.

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