Karst drainage of lake Chakanbacán and its relation to Icaiche Formation

• Published in: Boletín de la Sociedad Geológica Mexicana 2021-01, Vol.73 (1), p.1-11
• Main Authors: Leal-Bautista, Rosa M., Perry, Eugene C., Alvarado-Flores, Jesús, Alzate-Gavira, Liliana, Domínguez-Maldonado, Jorge A., Tapia-Tussell, Raúl
• Format: Article
• Language: English
• Subjects: Geology; Geosciences, Multidisciplinary; HIDROGEOLOGÍA / HYDROGEOLOGY
• ISSN: 1405-3322
• DOI: 10.18268/BSGM2021v73n1a021020

Sudden drainage of Lake Chakanbacán (also known as Om or Chakambacab) occurred naturally and without warning between 19 and 21 August, 2018. Lake Chakanbacán, located in southern Quintana Roo, 16.5 Km WNW of Nicolás Bravo, Quintana Roo is part of the western edge of the composite Morocoy-Nuevo Becak polje. Slumping associated with lake drainage has opened up fractures on the west bank of the lake, exposing gypsum of the Icaiche Formation. This occurrence establishes the western lake bank as the easternmost known outcrop of Icaiche gypsum in the area. Drainage of Lake Chakanbacán appears to be part of a karst process that proceeds by rapid dissolution and selective removal of layers of gypsum of the Icaiche Formation beneath the lake bed. Thus, the August 2018 lake drainage may demonstrate, in real-time, an ongoing weathering process responsible for a major regional geomorphic feature: the numerous internally drained karst depressions (poljes) up to >100km long in Campeche and southern Quintana Roo. It has been proposed that these poljes are collapse features resulting from removal in solution of gypsum of the Icaiche Formation. They occur both within and adjacent to a large area where the Icaiche Formation crops out, and, notably, over an estimated 10000 km² or more within that formation where massive beds of gypsum are present on the surface or beneath a thin protective cap of rock resistant to chemical weathering. El repentino colapso del lago Chakanbacán (también conocido como Om o Chakambacab) ocurrió de forma natural y sin previo aviso entre el 19 y el 21 de agosto de 2018. El Lago Chakanbacán, situado al sur de Quintana Roo, 16.5 Km WNW de Nicolás Bravo, Quintana Roo es parte del borde occidental del polje Morocoy-Nuevo Becak. El desplome asociado con el drenaje del lago ha abierto fracturas en la orilla oeste del lago, exponiendo el yeso de la Formación Icaiche. Esta ocurrencia establece la orilla occidental del lago como el afloramiento más oriental conocido del yeso de Icaiche en la zona. El drenaje del lago Chakanbacán parece ser parte de un proceso kárstico que ocurre por rápida disolución y eliminación selectiva de capas de yeso de la Formación Icaiche bajo el lecho del lago. Por lo tanto, el colapso del lago en agosto de 2018 puede demostrar, en tiempo real, un importante proceso de karstificación continuo responsable de una característica geomórologica regional: las numerosas depresiones kársticas drenadas internamente (poljes) de hasta > 100