Gypsum crystal morphologies in lake sediments for paleoclimate reconstructionsa case study in Fuente de Piedra playa-lake (Málaga)
- Lucia Martegani 1
- Fernando Gázquez 1
- Claudia Voigt 1
- Alejandro Jiménez Bonilla 2
- Miguel Rodríguez Rodríguez 2
- Klaus Reicherter 3
- 1 Department of Biology and Geology, University of Almería, Spain.
- 2 Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, Seville, Spain.
- 3 Institute of Neotectonics & Natural Hazards, RWTH Aachen University, Germany.
ISSN: 0213-683X
Year of publication: 2024
Issue: 76
Pages: 11-14
Type: Article
More publications in: Geogaceta
Abstract
Gypsum (CaSO4∙2H2O) is one of the most common evaporitic minerals on Earth. Its crystals exhibit diverse morphologies that can offer insights into their depositional environment. In this study, we analyzed the morphologies of gypsum deposits in a 14 m sedimentary sequence from Fuente de Piedra playa-lake (Málaga, Spain) to link the gypsum morphological variations and the lake sedimentary facies to changes in the past lake level. Precipitation of primary prismatic crystals prevailed during lake highstand periods. In contrast, lenticular gypsum crystals are consistently present throughout the entire core and do not seem to correlate to specific lake levels. An exception are macro-lenticular crystals, which seem to be associated with dry periods and high salinity water. Subrounded gypsum grains, eroded from former primary crystals, are also abundant along the sequence and usually concentrate in facies corresponding to stages of lake agitation during highstand periods. The absence of gypsum during lowstand periods can be attributed to relatively high contents of dissolved organic matter or, more likely, to reduced interaction between the lake and the saline groundwater aquifer beneath. Our results suggest that the occurrence of some gypsum morphologies can be used to infer paleo-lake levels.