Clay mineral transformations in anthropic organic matter-rich sediments under saline water environment. Effect on the detrital mineral assemblages in the Upper Chicamocha River Basin, Colombia

Low Temperature Illitization through Illite-Dioctahedral Vermiculite Mixed Layers in a Tropical Saline Lake Rich in Hydrothermal Fluids (Sochagota Lake, Colombia)

“…The Sochagota Lake accumulates saline waters of hydrothermal origin [24]. These waters are periodically discharged through the north exit of the dam into the Chicamocha River (flowing from east to west), in which basin the Sochagota Lake is included (Figure 2) [25,26]. The climate of the area can be classified as Cfb by the Köppen system, corresponding to a climate of subtropical highland (height, 2496 m) under oceanic conditions.…”

“…The small map represents the regional context of the global area, i.e., situation of the Paipa province (Boyaca region) in Colombia. Modified from [25].…”

“…From the geological perspective, the Sochagota Lake belongs to an important geothermal area that develops hydrothermal systems associated to volcanoes of the Andean Cordillera intruding cretaceous sediments rich in silicates (Figure 2). The most important outcrops as a source of sediments to the lake are rocks from the following formations: (a) Plaeners Formation (Cretaceous), made of intensely deformed radiolarites; (b) Los Pinos Formation (Cretaceous), formed by siltstones and quartz sandstone beds; (c) Labor-Tierna Formation (Cretaceous), made of coarse to fine-grained quartz sandstones; (d) Guaduas Formation (Maastrichtian-Paleocene), with clays and siltstones that include abundant intercalations of quartz sandstones; other siliceous cretaceous formations such as (e) Conejo Formation, (f) Churuvita Formation, (g) Une Formation, and (h) Tibasosa Formation; (i) Bogotá Formation (Late Paleocene-Early Eocene), consisting of quartz sandstones, siltstones and clays; (j) Tilatá Formation (Pliocene-Pleistocene) that discordantly overlies the Cretaceous and Paleogene materials and is predominantly made of quartz-rich sandy levels with beds of siltstones and clays; (k) Quaternary deposits of sands, silts, clays, and conglomerates overlying the Tilatá Formation corresponding to the most recent alluvial, lacustrine, and fluvio-lacustrine activity also deposited in the Chicamocha River Basin, mainly made of kaolinite and quartz [25,26]. The southern part of the Sochagota Lake basin is occupied by the Pliocene-Pleistocene acid pyroclastic deposits of the Paipa volcano (l in Figure 2) [20].…”

“…Kaolinite is the prevalent clay from the floodplains of the global Chicamocha River Basin and the Sochagota Lake Basin [25]. In fact, the Sochagota Lake drains to the Chicamocha River [15,25].…”

“…Kaolinite is the prevalent clay from the floodplains of the global Chicamocha River Basin and the Sochagota Lake Basin [25]. In fact, the Sochagota Lake drains to the Chicamocha River [15,25]. FESEM and HRTEM images as well as the sharp XRD peaks of the Sochagota Lake sediments clearly indicate that kaolinite is the main detrital mineral of the clay assemblage, especially in the zones of higher hydraulic energy, such as the southern part of the lake characterized by the presence of sediments enriched in coarse grain size fraction due to the prevalence of transport for the fine size fraction enriched in I-DV.…”