The Icaiche Formation, Per During Weathering of Quintana Roo)
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Boletín de la Sociedad Geológica Mexicana / 2019 / 1 The Icaiche Formation: Major contributor to the stratigraphy, hydrogeochemistry and geomorphology of the northern Yucatán Peninsula, Mexico Eugene C. Perry, Gudalupe Velazquez-Oliman, Rosa M. Leal-Bautista, Nicholas P. Dunning ABSTRACT Eugene C. Perry ABSTRACT RESUMEN Northern Illinois University, Geology and En- vironmental Geosciences, Emeritus, DeKalb, The Paleogene-Eocene Icaiche Formation, which La Formación Icaiche Paleoceno-Eoceno aflora en la zona sur Illinois 60115, USA. contains bedded gypsum deposits that cover an de los estados mexicanos de Yucatán, Campeche y Quintana estimated minimum area of 10000 km2, is located Roo. Abarca más de 10000 km2 y se caracteriza por capas Gudalupe Velazquez-Oliman in the southern parts of the Mexican states Yucatan, de depósitos de yeso. Esta formación ha sido poco estudiada ya Centro de Innovación e Investigación para el Campeche and Quintana Roo. The formation has que el afloramiento se presenta en un área con limitado acceso, Desarrollo Sustentable, Javier Rojo Gómez, been little studied because it crops out in an area limitada población y reducida actividad económica. Estas Mza. 9, Lote 1, Local F, Puerto Morelos, Quin- with limited access, few people, and little economic circunstancias están directamente relacionadas con la presencia tana Roo. C.P. 77580, Mexico. activity. Low population density is a consequence de sulfato disuelto en el agua subterránea, consecuencia de la of the sulfate-contaminated water that is produced erosión y disolución de los depósitos de yeso de la Formación during weathering and dissolution of the gypsum que afectan las condiciones químicas del agua útil, generando Rosa M. Leal-Bautista deposits in the formation. The Icaiche Formation poco interés de la población por establecerse en esta zona. [email protected] occupies a considerable part of the physiographic La Formación Icaiche ocupa una zona considerable del área Centro de Investigación Científica de Yucatán, area known as the Elevated Interior Region (EIR) fisiográfica conocida como Región Interior Elevada (Elevated A.C., Unidad de Ciencias del Agua, Calle 8, of the Yucatán Peninsula, which encompasses a Interior Region [EIR]) de la Península de Yucatán, la cual No. 39, Mza. 29, SM 64, Cancún, Quintana terrain that the Maya occupied with varying success incluye terrenos ocupados por los Mayas, con cierto éxito por casi for almost two millennia and finally almost com- Roo C.P. 77524, Mexico. dos mil años y que fueron finalmente abandonados para el 950 pletely abandoned by about 950 CE. During their CE. Estudios arqueológicos han señalado que las condiciones tenure, the Maya survived and at times prospered Nicholas P. Dunning de apogeo en esta región se dieron cuando los mayas usaron y in this region of unpalatable groundwater by using adaptaron las depresiones kársticas de la zona, denominadas University of Cincinnati, Geography Depart- and adapting natural depressions (called bajos) for “bajos”, como los principales suministros de agua. Incluso el ment, 401 Braunstein Hall, 2600 Clifton Ave. water supply and, somewhat later, by using abun- aprovechamiento de los sedimentos arcillosos de la zona permitió Cincinnati, OH, 45221, USA. dant impermeable local clays in construction of la construcción de sistemas de almacenamiento y de transporte dams and ingenious systems for water storage and del agua. Sin embargo, esto no fue constante debido a la alta transport. Because of the relatively high solubility solubilidad del yeso que predomina en los afloramientos de la of gypsum, the Icaiche Formation has had an Formación Icaiche. Esta formación tiene influencia en las carac- outsize influence on hydrologic and geomorphic terísticas de permeabilidad de la zona y en las características features and groundwater geochemistry beyond hidrogeológicas y geomorfológicas tanto en superficie como en las where it crops out and into parts of the Yucatán secciones no afloradas de la Formación. Sin embargo, su impor- Peninsula where it is present in the subsurface, par- ticularly those places where it encounters flowing tancia no ha sido reconocida ni la hidrogeoquímica que puede groundwater. In this study, we propose that gypsum presentar los flujos subterráneos en la Península de Yucatán. dissolution, followed by collapse of overlying rock, En este trabajo se propone que la disolución del sulfato de calcio was important in: 1) the formation of poljes (large, (yeso) seguida por los procesos de colapsos kársticos generaron: partly or completely enclosed karst basins with flat 1) la formación de poljes (depresiones kársticas elongadas que floors and interior drainage) along the east and se presentan como valles cerrados) que aparecen en las márgenes west margins of the EIR; 2) the development of este y oeste de la EIR; 2) la formación de geoformas kársticas deep karst in north central Yucatán state; and 3) profundas que se presentan en la zona norte-central del estado de the formation of irregular terrains, extensive brec- Yucatán; y 3) la formación de las irregularidades (extensive ciation of rock, and highly varying water quality in brecciation of rock), así como la variación hidrogeoquímica the area at the eastern margin of the EIR (between de los flujos subterráneos en la margen este de la EIR (entre Lake Chichancanab and Felipe Carrillo Puerto, Lago Chicancanab y la Formación Felipe Carrillo Puerto en Quintana Roo). Argillaceous sediment released Quintana Roo. Así mismo, se sugiere que los sedimentos arci- during weathering of the Icaiche Formation, per- llosos formados durante los procesos de erosión de la Formación haps mixed with siliceous components of impact Icaiche y su posible mezcla con depósitos de sílice del impacto deposits from the Chicxulub Impact may have del Chixchulub pudieron afectar la permeabilidad de las rocas affected the permeability of post-Eocene marine sedimentarias de origen marino del post-Eoceno, posiblemente sedimentary rocks, perhaps including local facies incluyendo las facies locales de la Formación Felipe Carrillo of the Carrillo Puerto Formation, formed on the Puerto que se presentan en el margen sureste de la Península. southeast margin of the Peninsula. The resulting Lo anterior resultó en un material con baja permeabilidad para BOL. SOC. GEOL. MEX. 2019 rocks have markedly lower permeability than rocks la zona sur de la parte mexicana de la península de Yucatán VOL. 71 NO. 3 of the more northerly lowlands of the Mexican por- comparada con la zona norte cuya permeabilidad permite la P. ### ‒ ### tion of the Yucatán Peninsula that host a pervasive presencia del lente de agua dulce que se superpone a la intrusión http://dx.doi.org/10.18268/BSGM2019v71n3a# fresh water lens overlying a saline intrusion. salina. Keywords: Yucatan Peninsula, gyp- Palabras clave: Península de Yucatán, Manuscript received: Corrected manuscript received: sum, stratigraphy, hydrogeochemistry, yeso, estratigrafía, hidrogeoquímica, Manuscript accepted: karst. carst. The Icaiche Formation: stratigraphy, hydrogeochemistry and geomorphology 2 / Boletín de la Sociedad Geológica Mexicana / 2019 1. Introduction Bonet who made an extensive field study of the area between 1958 and 1960 (Butterlin and Bonet, The little-studied Icaiche Formation crops out in 1960). Lacking identifiable fossils for correlation, southern Campeche, southern Quintana Roo, and they used the presence of bedded evaporite as the INTRODUCTION / STRATIGRAPHIC RELATIONS southernmost Yucatán state, Mexico. It is worth defining characteristic of the Icaiche Formation. noting that rocks equivalent or similar to those of The importance of this characteristic will be the Icaiche Formation exist in northern Guate- emphasized here. The outcrop boundaries of the mala and northern Belize, but these have not been Icaiche Formation within Mexico, shown in Fig- formally correlated. ure 1, conform to those in the map of the Estados This paper examines ways in which gypsum and de Campeche, Quintana Roo y Yucatán, 2007 (SGM, probably argillaceous material of that formation 2017). Note that it is probable that Icaiche rocks may have exerted an outsize influence on the continue south into Belize and Guatemala (Flores, present hydrogeology and geomorphology of the 1952). Mexican portion of the Yucatán Peninsula, includ- The Icaiche Formation consists of Paleocene-lower ing all parts of the three states where the Icaiche Eocene lagoonal rocks whose detailed stratigraphy Formation is present either at the surface or in is indeterminate because recrystallization has the subsurface (Figure 1). This inclusive region is made fossil correlation difficult. Despite poor henceforth referred to simply as “Yucatán” unless exposure, it is possible to use the quarry symbols that word is qualified to indicate the state of on the map of SGM (2017) to define an outcrop Yucatán. Exposure of Icaiche Formation rocks is area of about 10000 km2, which is centered on sparse, and the contact relations with other forma- Xpujil, Campeche to approximate the minimum tions (Figure 1) are incompletely known because area of surface exposure of Paleocene-Eocene of thick tropical vegetation, intense weathering, bedded gypsum within Yucatán. This area is and limited road access. Furthermore, gypsum shown by the rectangle labelled “Outcrop Area abundance can be obscured because its dissolution of Gypsum Member” in Figure 1. We shall refer can produce a blanket of unconsolidated overbur- to these gypsum beds informally as the gypsum den by