Structural evidence of enhanced active subsidence at the bottom of a maar: Rincón de Parangueo, México
José Jorge Aranda-Gómez, Mariano Cerca, Luis Rocha-Treviño, Jaime Jesús Carrera-Hernández, Gilles Levresse, Jesús Pacheco, Vsevolod Yutsis, Jorge Arturo Arzate-Flores, Elizabeth Chacón, Hugo Beraldi-Campesi, 2017. "Structural evidence of enhanced active subsidence at the bottom of a maar: Rincón de Parangueo, México", Monogenetic Volcanism, K. Németh, G. Carrasco-Núñez, J. J. Aranda-Gómez, I. E. M. Smith
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Rincón de Parangueo is a Quaternary maar that has been recently desiccated. The crater was partially occupied by a soda lake, and near the shoreline microbialites have formed. Evaporites (mainly trona and halite) precipitated as the water level dropped. Active subsidence of the lake floor (c. 24 m since 1980) produced countless structures close to the lakeshore, where deformation is extensional. Closer to the depocentre, in the western half of the basin, gliding/spreading produced folds and mud-injection domes. The most remarkable structure throughout the basin is a monocline that forms a ring-like, nearly continuous scarp, approximately 15 m high, which in the eastern half of the basin was produced as a fault-propagation fold developed above the buried diatreme–country rock boundary. A more diffuse (wider) monocline, locally associated with compressive structures, occurs in the western half of the basin. These structures are interpreted as having developed above a gently inclined, irregular lake sediment–country rock (andesite) interphase. The monocline was modified by high-angle extensional faults/fractures with large heaves/apertures. In the eastern half of the basin, there is a second (outer) scarp, approximately 13 m high, formed by a high-angle, listric, normal fault. Rollover antiforms occur in the hanging wall of this structure. Rincón is an example of centripetal gravitational gliding/spreading.