Low Temperature Illitization through Illite-Dioctahedral Vermiculite Mixed Layers in a Tropical Saline Lake Rich in Hydrothermal Fluids (Sochagota Lake, Colombia)
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MDPI
Materia
Sochagota Lake Hydrothermal inputs Illite–dioctahedral vermiculite mixed layers Illitization
Date
2021Referencia bibliográfica
Cifuentes, G.R.; Jiménez-Millán, J.; Quevedo, C.P.; Nieto, F.; Cuadros, J.; Jiménez-Espinosa, R. Low Temperature Illitization through Illite-Dioctahedral Vermiculite Mixed Layers in a Tropical Saline Lake Rich in Hydrothermal Fluids (Sochagota Lake, Colombia). Minerals 2021, 11, 523. https://doi.org/10.3390/min 11050523
Sponsorship
Spanish research project PGC2018-094573-B-I00 - the MCIU-AEI-FEDER; RNM-325 of the Junta de Andalucía (Spain); Asociación Universitaria Iberoamericana de Posgrado (AUIP) and the Universidad de Boyacá; Colombian Research groups Gestión Ambiental COL0005468; Gestión de Recursos Hídricos COL0005477Abstract
In this investigation, we showed that high salinity promoted by hydrothermal inputs,
reducing conditions of sediments with high content in organic matter, and the occurrence of an
appropriate clay mineral precursor provide a suitable framework for low-temperature illitization
processes. We studied the sedimentary illitization process that occurs in carbonaceous sediments from
a lake with saline waters (Sochagota Lake, Colombia) located at a tropical latitude. Water isotopic
composition suggests that high salinity was produced by hydrothermal contribution. Materials accumulated in the Sochagota Lake’s southern entrance are organic matter-poor sediments that contain
detrital kaolinite and quartz. On the other hand, materials formed at the central segment and near
the lake exit (north portion) are enriched in organic matter and characterized by the crystallization
of Fe-sulfides. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high
resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray spectrometry
(EDX) data allowed for the identification of illite and illite-dioctahedral vermiculite mixed layers
(I-DV), which are absent in the southern sediments. High humidity and temperate climate caused
the formation of small-sized metastable intermediates of I-DV particles by the weathering of the
source rocks in the Sochagota Lake Basin. These particles were deposited in the low-energy lake
environments (middle and north part). The interaction of these sediments enriched in organic matter
with the saline waters of the lake enriched in hydrothermal K caused a reducing environment that
favored Fe mobilization processes and its incorporation to I-DV mixed layers that acted as mineral
precursor for fast low temperature illitization, revealing that in geothermal areas clays in lakes favor
a hydrothermal K uptake.