Abstract

RODRIGUEZ, Lyna M  and  SANCHEZ, John J.. Morphometry, stratigraphy, petrography, and geochemistry of El Morro scoria cone, La Argentina municipality (Huila, Colombia). bol.geol. [online]. 2018, vol.40, n.3, pp.49-65. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v40n3-2018003.

This work is a contribution to the geological knowledge of El Morro eruptive center (CEM), located in the State of Huila (Colombia), by means of the morphometric analysis of the edifice, stratigraphic survey of pyroclastic deposits, and petrographic and geochemical analysis of juvenile clasts. The pyroclastic deposits were characterized in terms of the geometry of the layers, textural and granulometric variations, mineralogy, and whole-rock chemistry. The CEM is a simple and well-preserved scoria cone, and thus it is considered young.

It is a mafic eruptive center, composed by pyroclastic deposits, grouped in three distinguishable accumulation packages at the outcrop scale by their normal-to-reverse variable grading. The mostly juvenile clasts that make up the stratigraphic packages vary in size between ash and bomb. The petrography and geochemistry of the CEM clasts indicate the emission of a basaltic magma. From the morphometric relationships and the discrimination diagrams for the geotectonic environment, it was concluded that the fragments analyzed suggest affinity with continental arc basalts and their formation environment is associated to subduction.

Keywords : El Morro scoria cone; stratigraphy; geochemistry; morphometry; petrography.

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