Abstract

RUEDA-GUTIERREZ, Jesús Bernardo. New evidences of magmatism in the Paipa geothermal system, Boyacá, Colombia. Bol. geol. [online]. 2020, vol.42, n.3, pp.51-79.  Epub Aug 31, 2020. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v42n3-2020002.

The domes of the geothermal area of Paipa were characterized in three sectors. The Alto Los Volcanes is formed by two zones where four elevations are evident that protrude from the surface, with strongly weathered outcrops but with evident volcanic textures demarcated by big potassium feldspar crystals in a white matrix. In Quebrada Honda there is a domic structure dominated by feldspar megacrystals while the Alto Los Godos is formed by five domes with porphyritic texture and feldspar crystals. Petrographically similar characteristics are present in the three sectors, with the presence of potassium feldspar (sanidine/anortoclase) + plagioclase (albite) + amphibole (hornblende) + biotite. Variable amounts of kaolinite are shown especially for some feldspar replacements and as veins. Chemically, the domes are classified as rhyolites/trachidacites, with a chemical signature of subcalcaline magmas of calcoalkaline series rich in potassium typical of volcanic arcs. The REE shows an enrichment of the LREE with averages of (La/Sm)N between 5.944 and 14.726 respect to the HREE with values of (Gd/Yb)N between 0.626 and 2.318 and with an important positive anomaly of EuN/(SmN*GdN)1/2 between 1.321 and 3.84. Data Ar-Ar in amphibole and feldspar, gave as a result for the sector of Alto Los Volcanes and Quebrada Honda ages of 1.76 and 1.8 Ma respectively, on the other hand, for the Alto Los Godos were recorded for three domes ages of 2.8, 2.7 and 2.6 Ma. Evidences of intrusive bodies that have not emerged were identified in the north and south of the work area based on the geomorphology and geophysical results of other authors. The cartography in these sectors did not show volcanic lithology, the geomorphology and some relationships with the geophysics acquired in the area, allow us to suppose that they are intrusions without superficial expressions increasing the possibilities of heat contribution to the geothermal system.

Keywords : Rhyolitic domes; Paipa’s Volcanism; Paipa’s geothermal system.

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