Water stable isotopes (δ2H and δ18O) in the Yucatán Peninsula, Mexico

Cejudo, Eduardo; González, Gilberto Acosta; Leal‐Bautista, Rosa María; Medina, Héctor E.

doi:10.24850/j-tyca-2022-02-10

Cited by 4 publications

(3 citation statements)

References 30 publications

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“…Since it was proposed that Hells Bells are growing within a 1–2 m thick pelagic redoxcline in the lowermost portion of the freshwater lens 2 , the stable oxygen isotope record measured in Hells Bells calcite mainly depends on the isotopic composition of the meteoric groundwater (freshwater lens). The freshwater’s isotopy is dependent on (1) the isotopic composition of precipitation, since groundwater on the YP is a long-term integrator of precipitation and infiltration 26 , and (2) to a lesser extent on molecular viscous diffusion between the saline groundwater (δ 18 O = − 0.3 to 1.3‰ 26 ) and the freshwater lens (δ 18 O = − 8.8 to 6.8‰ 26 ). A three-year monitoring of drip- and groundwater in the Rio Secreto Cave near Playa del Carmen about 30 km south of our study area (e.g., El Zapote, Fig.…”

Section: Discussionmentioning

confidence: 99%

Mid- to late Holocene sea-level rise recorded in Hells Bells 234U/238U ratio and geochemical composition

Schorndorf

Frank

Ritter³

et al. 2023

Sci Rep

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Hells Bells are underwater secondary carbonates discovered in sinkholes (cenotes) southeast of Cancun on the north-eastern Yucatán peninsula, Mexico. These authigenic calcite precipitates, reaching a length of up to 4 m, most likely grow in the pelagic redoxcline. Here we report on detailed 230Th/U-dating and in-depth geochemical and stable isotope analyses of specimens from cenotes El Zapote, Maravilla and Tortugas. Hells Bells developed since at least ~ 8000 years ago, with active growth until present day. Initial (234U/238U) activity ratios (δ234U0) in Hells Bells calcite decreas from 55 to 15‰ as sea level converges toward its present state. The temporal evolution of the geochemistry and isotope composition of Hells Bells calcites thus appears to be closely linked to sea-level rise and reflects changing hydrological conditions (desalinization) of the aquifer. We suggest that decelerated leaching of excess 234U from the previously unsaturated bedrock traces Holocene relative sea-level rise. Considering this proxy, the resulting mean sea-level reconstruction contains half as much scatter, i.e. improves by a factor of two, when compared to previously published work for the period between 8 and 4 ky BP.

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Section: Discussionmentioning

confidence: 99%

Mid- to late Holocene sea-level rise recorded in Hells Bells 234U/238U ratio and geochemical composition

Schorndorf

Frank

Ritter³

et al. 2023

Sci Rep

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“…Adicionalmente, los isótopos estables (δ 2 H y δ 18 O) de la DAS son similares al agua subterránea de la región a una distancia de entre 1.5 y 3 km de la costa. El valor de δ 18 O alrededor de -4 ‰ indica relativa estabilidad en las características del agua subterránea en la zona (Cejudo et al 2022), el ligero incremento a -2.5 ‰ en abril 2020 sugiere mezcla de masas de agua de diferente composición isotópica, lo más probable es que sea agua de mar (Gat 2010). La resistividad real obtenida de las secciones geoléctricas, hacen suponer la existencia de una matriz de arena o caliza, saturada entre 2.5 y 7 m de profundidad con agua salobre (Zamora-Luria et al 2019), y completamente saturada con agua salada por debajo de esta profundidad; una lente de agua dulce libre de aproximadamente 2.5 m de espesor y la presencia de zonas de baja resistividad que se asocian a recarga (24 a 27 m en el eje horizontal).…”

Section: Discussionunclassified

Caracterización hidroquímica y geofísica de una descarga de agua subterránea en Quintana Roo, México

Cejudo

Acosta‐González

Ortega-Camacho³

et al. 2022

Ecosist. Recur. Agropec.

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Las descargas de agua subterránea (DAS) aportan información para entender la hidrogeología local de una región. Este estudio describe de manera integral una DAS en la zona costera de Quintana Roo, cuantificando la descarga volumétrica y describiendo la hidroquímica y la geofísica del sitio para contribuir al conocimiento del acuífero kárstico costero en Quintana Roo. La DAS descrita es una cavidad ovalada con un área aproximada de 0.0507 m2 donde mensualmente se cuantificaron elementos mayores, silicatos, metales e isótopos estables del agua (δ2H y δ18O). Con estos últimos se calculó el aporte de la precipitación en la descarga instantánea, además se realizaron tomografías de resistividad eléctrica para identificar zonas saturadas y zonas de flujo. La alcalinidad, silicatos, sodio y cloruros disminuyen y el potencial redox aumentan con la precipitación pluvial, que evidencian la recarga. El mayor aporte del agua de mar se observa cuando el flujo volumétrico de la DAS es bajo, por lo que el agua es de tipo clorurada sódico potásica. Domina el aporte de agua subterránea, el agua de mar contribuye entre 2 y 16% del flujo volumétrico. La contribución de la precipitación pluvial es de entre 1% y 15% y no se observa de manera inmediata. La geofísica apunta a un lente de agua dulce libre de aproximadamente 2.5 m de espesor y zonas de recarga, así como la existencia de pequeños canales de conducción por donde fluye el agua subterránea. Los resultados capturan eventos locales y regionales de recarga del acuífero.

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“…The dissolved CO 2 in the redoxcline is fueled by organic matter decomposition in the anoxic saline groundwater mass and host rock dissolution buffering the acid produced in microbial organic matter decay via sulphate reduction [2]. Consequently, changes in δ 13 The stable oxygen isotope record measured in Hells Bells calcite mainly depends on the isotopic composition of the freshwater, which is dependent on (i) the isotopic composition of precipitation, since groundwater on the YP is a long-term integrator of precipitation and in ltration [22], and (ii) to a lesser extent on molecular viscous diffusion between the saline groundwater (δ 18 O = ~ 0‰) and the freshwater lens. A three-year monitoring of drip-and groundwater in the Rio Secreto Cave near Playa del Carmen about 30 km south of our study area (e.g., El Zapote, Fig.…”

Section: Stable Carbon and Oxygen Isotopesmentioning

confidence: 99%

Mid- to late Holocene sea-level rise recorded in Hells Bells 234U/238U ratio and geochemical composition

Schorndorf¹,

Frank²,

Ritter³

et al. 2023

Preprint

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Hells Bells are underwater secondary carbonates discovered in sinkholes (cenotes) southeast of Cancun on the north-eastern Yucatán peninsula, Mexico. These authigenic calcite precipitates, reaching a length of up to 4 m, most likely grow in the pelagic redoxcline. Here we report on detailed 230Th/U-dating and in-depth geochemical and stable isotope analyses of specimens from cenotes El Zapote, Maravilla and Tortugas. Hells Bells developed since at least ~ 8 thousand years ago, with active growth until present day. Initial (234U/238U) activity ratios (δ234U0) in Hells Bells calcite decreases from 55 to 15‰ as sea level converges toward its present state. The temporal evolution of the geochemistry and isotope composition of Hells Bells calcites thus appears to be closely linked to sea-level rise and reflects changing hydrological conditions (desalinization) of the aquifer. We suggest that decelerated leaching of excess 234U from the previously unsaturated bedrock traces Holocene relative sea-level rise. Considering this proxy the resulting mean sea-level reconstruction contains half as much scatter, i.e. improves by a factor of two, if compared to previously published work for the period between 8 and 4 ky BP.

show abstract

Water stable isotopes (δ2H and δ18O) in the Yucatán Peninsula, Mexico

Cited by 4 publications

References 30 publications

Mid- to late Holocene sea-level rise recorded in Hells Bells 234U/238U ratio and geochemical composition

Mid- to late Holocene sea-level rise recorded in Hells Bells 234U/238U ratio and geochemical composition

Caracterización hidroquímica y geofísica de una descarga de agua subterránea en Quintana Roo, México

Mid- to late Holocene sea-level rise recorded in Hells Bells 234U/238U ratio and geochemical composition

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