Active sinking at the bottom of the Rincón de Parangueo Maar (Guanajuato, México) and its probable relation with subsidence faults at Salamanca and Celaya

Abstract

Rincon de Parangueo is a Quaternary maar that had a perennial lake until the 1980s. The lake was gradually desiccated as a consequence of drawdown in the Salamanca-Valle de Santiago regional aquifer and now functions as a playa-lake. In contrast with the features observed in other crater-lakes in the region (La Alberca, Cíntora, and San Nicolás), which also dried up at the same time, the bottom of the Rincón crater displays clear evidence of active deformation associated with mass movement of lake sediments towards the depocenter inside the crater. The most conspicuous topographic feature is a 10 -12 m high scarp parallel to the former lake coast. The scarp is produced by an annular shaped normal fault system, down towards the depocenter. Evidence of active mass movement is observed along the topographic scarp. Rotational slides associated with rollover anticlines and local grabens produced by antithetic faults are common on the eastern and northern parts of the scarp. Planar slides with open folds at their base occur at western part of the lake basin.Evaporites (trona, thermonatrite, eitelite, halite, and silvite) are abundant in the playa-lake sediments. Their presence makes us believe that a mass removal process is acting as a consequence of salt dissolution and infiltration of the brine towards the aquifer. This process, probably in conjunction with lake sediment compaction and/or diatreme subsidence, may explain the significantly higher fault displacement rate observed inside the crater ( ≈ 50 cm/year ) in comparison with active faults elsewhere in the Salamanca-Valle de Santiago aquifer ( ≈ 6 cm/year ).Keywords: drawdown, maar, evaporite, stromatolite, landslide. Resumen

Petrology and geochemistry of the Valle de Santiago lower-crust xenoliths: Young tectonothermal processes beneath the central Trans-Mexican volcanic belt

“…1). These spectacular maars have attracted geoscientists for more than a century, who have studied them from the simplest morphological aspects (e.g., Ordóñez, 1900Ordóñez, , 1906 to their environmental attributes (Park, 2005;Armienta et al, 2008;Kienel et al, 2009;Aranda-Gómez et al, 2013) and their petrologic, geochronological, geochemical, and volcanological features (cf. Cano-Cruz and Carrasco-Núñez, 2009).…”

“…The quest to understand how this continental crust has influenced the composition and evolution of the Trans-Mexican volcanic belt magmas in the last 20 m.y. is also a major subject of debate, and many rather contrasting views have been advanced, including those that confer a fundamental importance Petrology and geochemistry of the Valle de Santiago lower-crust xenoliths: Young tectonothermal processes beneath the central Trans-Mexican volcanic belt www.gsapubs.org | Volume 6 | Number 5 | LITHOSPHERE to crustal contamination (e.g., Kudo et al, 1985;McBirney et al, 1987;Verma, 1999Verma, , 2000Verma, , 2001Verma and Hasenaka, 2004;Chesley et al, 2002;Cebriá et al, 2011), and others that minimize that role (e.g., Luhr and Carmichael, 1985;Wallace and Carmichael, 1999;Martínez-Serrano et al, 2004;Gómez-Tuena et al, 2006, 2013Straub et al, 2011). However, relevant data on the structure and composition of the crystalline basement (granitic and metamorphic rocks) beneath the Valle de Santiago volcanic field based on geological outcrops (e.g., Centeno-García, 2005), gravity and seismicity (Campillo et al, 1996;Molina-Garza and Urrutia-Fucugauchi, 1993;Urrutia-Fucugauchi and Flores-Ruiz, 1996), and rare deep-seated xenoliths or megacrysts (Righter and Carmichael, 1993;Aguirre-Díaz et al, 2002;Urrutia-Fucugauchi and Uribe-Cifuentes, 1999;Ortega-Gutiérrez et al, 2008a) are rather inconclusive, in contrast to the abundant and well-studied lower crust and mantle xenoliths that occur in many places of northern Mexico (Nimz et al, 1986;Ruiz et al, 1988;Hayob et al, 1989;Pier et al, 1989;Rudnick and Cameron, 1991;Schaaf et al, 1994;Aranda-Gómez and Luhr, 1996).…”

Application of InSAR and Gravimetry for Land Subsidence Hazard Zoning in Aguascalientes, Mexico

“…Many studies have reported the occurrence of land subsidence and its effects [3][4][5][6][7][8][9][10]. Studies dealing with monitoring and detecting subsidence are numerous [11][12][13][14][15][16][17], as well as works addressed to land subsidence modeling for calculating the expected magnitudes and rates of subsidence for different scenarios [18][19][20][21][22][23].…”

Physical experiments of land subsidence within a maar crater: insights for porosity variations and fracture localization

“…Rincón de Parangueo was one of four maar craters nearby the locality of Valle de Santiago village that used to have a perennial lake and nowadays is partially occupied by a brine lake. During the 1980's progressive desiccation began as a consequence of water overdraft from the regional aquifer that used to feed the lake (Escolero-Fuentes and Alcocer-Duran, 2004; Aranda- Gómez et al, 2013). Detailed geologic mapping in the sediments of the lake bed shows clear evidence of rapid active subsidence contemporaneous to desiccation (ArandaGómez et al, 2010(ArandaGómez et al, , 2013Aranda-Gómez and CarrascoNuñez, 2014;Cerca et al, 2014).…”

“…Water withdrawal in the aquifer system adjacent to the volcanic field has been pointed out as the cause for deformation and desiccation of the lake since the 1980's decade (Escolero-Fuentes and Alcocer-Duran, 2004;Aranda-Gómez et al, 2013;and references therein). Fragmentation of the country rock due to diatreme formation is likely to be contained within the maar-diatreme and less likely to propagate down to deeper levels into the feeder dike.…”