New determination of gypsum isotope fractionation factor

Gypsum is a low temperature mineral of relevance for the understanding of evaporitic and late hydrotermal scenarios. Gypsum deposits are spread all over the geological record and their crystals may contain important information about the history of the seas

Unraveling the sulfate sources of (giant) gypsum crystals using gypsum isotope fractionation factors.

We combine newly determined isotope fractionation factors of gypsum precipitated in the laboratory with the isotopic compositions of natural anhydrite and gypsum to unravel the sulfate sources of the giant selenite crystals in the Naica mine (Chihuahua, Mexico). Gypsum was precipitated in the laboratory from CaSO4-NaCl-H2O solutions across a broad temperature range to establish the isotopic fractionation behavior of the sulfate molecule between the solid and dissolved phase. Oxygen isotopes show a significant fractionation dependence on temperature, with the solid phase more depleted in light isotopes with decreasing temperature. Sulfur isotopes display only a weak but similar dependence on temperature. At high salinity (4.5 M NaCl) no temperature dependence was found for the isotope composition. Based on this fractionation behavior, we attempt to elucidate the origin of the sulfate source(s) responsible for the formation of the (giant) gypsum crystals in the Naica mine. Detailed analysis of the isotopic composition of anhydrite, gypsum, and water samples strongly suggests that different types of anhydrite (of hypogenic and sedimentary origin) were dissolved to form these unique gypsum formations. The homogeneous isotopic composition of most gypsum crystals analyzed reveals an effective hydrodynamic mixing and a slow kinetics of precipitation fed by solutions of calcium sulfate from different anhydrite sources

New determination of gypsum isotope fractionation factor

Gypsum is a low temperature mineral of relevance for the understanding of evaporitic and late hydrotermal scenarios. Gypsum deposits are spread all over the geological record and their crystals may contain important information about the history of the seas

Unraveling the sulfate sources of (Giant) gypsum crystals using gypsum isotope fractionation factors

We combine newly determined isotope fractionation factors of gypsum precipitated in the laboratory with the isotopic compositions of natural anhydrite and gypsum to unravel the sulfate sources of the giant selenite crystals in the Naica mine (Chihuahua, Mexico). Gypsum was precipitated in the laboratory from CaSO-NaCl-HO solutions across a broad temperature range to establish the isotopic fractionation behavior of the sulfate molecule between the solid and dissolved phase. Oxygen isotopes show a significant fractionation dependence on temperature, with the solid phase more depleted in light isotopes with decreasing temperature. Sulfur isotopes display only a weak but similar dependence on temperature. At high salinity (4.5M NaCl) no temperature dependence was found for the isotope composition. Based on this fractionation behavior, we attempt to elucidate the origin of the sulfate source(s) responsible for the formation of the (giant) gypsum crystals in the Naica mine. Detailed analysis of the isotopic composition of anhydrite, gypsum, and water samples strongly suggests that different types of anhydrite (of hypogenic and sedimentary origin) were dissolved to form these unique gypsum formations. The homogeneous isotopic composition of most gypsum crystals analyzed reveals an effective hydrodynamic mixing and a slow kinetics of precipitation fed by solutions of calciumsulfate from different anhydrite sources.This work has been carried out within the framework of project CGL2010-16882 of the Spanish Ministerio de Economía y Competitividad and cofunded with Fondo Europeo de Desarrollo Regional. A. E. S. Van Driessche is grateful for FWO grant 1523115N. We acknowledge C. Ayora (Consejo Superior de Investigaciones Científicas) and C. Johnson (US Geological Survey) for useful insights on the manuscript and S. Bottrell and an anonymous reviewer for their constructive review. M. Ossorio acknowledges the Junta para la Ampliación de Estudios–Predoc fellowship

Nueva interpretación del Passet de Segària y La Penya de l'Àguila en el contexto de las guerras civiles romanas

Estudio sobre un conjunto de yacimientos situados sobre promontorios en la costa norte alicantina. En la historiografía anterior se habían identificado como pequeños poblados iberos ocupados entre los siglos II y I a.C., contemporáneos por tanto de la conquista de Hispania. Ahora sin embargo se han reinterpretado como fortines romanos de las guerras civiles sertorianas.Proyectos I+D HAR2009-11334 y HAR2012-32754, financiados por los Ministerios de Ciencia e Innovación y de Economía y Competitividad, respectivamente

Nueva interpretación del Passet de Segària y La Penya de l'Àguila en el contexto de las guerras civiles romanas

Estudio sobre un conjunto de yacimientos situados sobre promontorios en la costa norte alicantina. En la historiografía anterior se habían identificado como pequeños poblados iberos ocupados entre los siglos II y I a.C., contemporáneos por tanto de la conquista de Hispania. Ahora sin embargo se han reinterpretado como fortines romanos de las guerras civiles sertorianas.Proyectos I+D HAR2009-11334 y HAR2012-32754, financiados por los Ministerios de Ciencia e Innovación y de Economía y Competitividad, respectivamente