Search results for "Gypsum"

The geochemical riddle of “low-salinity gypsum” deposits

2022

International audience; Gypsum makes up about one fifth of giant salt deposits formed by evaporation of seawater throughout Earth’s history. Although thermodynamic calculations and precipitation experiments predict that gypsum precipitates when the salinity of evaporating seawater attains about 110 g kg-1, gypsum deposits of the Mediterranean Salt Giant often bear the geochemical signature of precipitation from less saline water masses. Addressing this geochemical riddle is important because marine gypsum deposition and continental gypsum erosion affect the global carbon cycle. We investigated gypsum deposits formed in the marginal basins of the Mediterranean Sea during the Messinian Salini…

Reconstruction of the environmental evolution of a Sicilian saltmarsh (Italy)

2013

The present study deals with the reconstruction of the environmental evolution of a Trapani saltmarsh (southwestern Sicily, Italy) by combining different analytical approaches such as metal content evaluation, low-field nuclear magnetic resonance (NMR) relaxometry, and benthic foraminifera identification. A 41 cm core was collected in the sediments of a Trapani saltmarsh (southwestern Sicily, Italy) at a water depth of about 50 cm. Different time intervals were recognized, each characterized by peculiar features that testify different environmental conditions. In particular, the bottom layers of the sediment core (41–28 cm) comprised the lowest amount of mud fraction, only some selected met…

Gypsum and giant canes in the Sicilian traditional architecture

2014

Giant cane is a natural, eco-friendly and low-cost product that is very common in the Mediterranean area. As far as the Sicilian tradition is concerned, it has been combined with gypsum, a material with the same qualities. Reeds and gypsum have been used as a traditional composite material that is able to join and improve their peculiarities of lightness and insulation, and to utilize the bearing skill of the hardiest reeds and the fire protection and moulding skills of gypsum. This combination of poor and easy-to-find materials has been used very frequently in Sicilian traditional constructions. It is possible to see roofs with inclined floors; some wooden floors with reeds and gypsum used…

Peculiar wall channels connected to fault breccia in the Grotta di Entella gypsum cave (Western Sicily, Italy)

2010

The "Paleorisorgenza" of the Monte Conca karst system (Campofranco - CL)

2009

New Knowledge on the Monte Conca gypsum karst system (Central-Western Sicily).

2009

New knowledge on the Monte Conca gypsum karst system (Central-western Sicily, Italy)

2011

The Monte Conca karst system is located in Central-Western Sicily, where Messinian evaporites are widespread. Here, the evaporites lie on lower Messinian-middle Serravallian clayey-marly-sandy deposits and are overlain locally by Pliocene marly limestones. These successions are affected by E-W, and to a lesser degree N-S and NW-SE, high-angle faults that have also produced lateral contacts between the gypsum units and the clayey-marly deposits. The cave passages reachaltogether about 2.4 km in lengthand 130 m in depth, and the system consists of a sink cave, a resurgence and a relict resurgence. At large scale it is characterized by superimposed levels of sub-horizontal galleries connected …

Sistemi costruttivi tradizionali in gesso nell’architettura siciliana

2020

Chalks outcrops characterize all the central-western territory in Sicily. They are different in types and extension and tangibly mark the presence of the well-known sulphurus chalky series. In the same areas it is possible to see several traditional buildings built, even in their structures, using gypsum, an material which is unusual in other contexts. In some cases the chalk outcrop makes up even the base of a building. This text describes different kinds of walls, floors, vaults and flooring where gypsum is the main material.

Authigenic phase formation and microbial activity control Zr, Hf, and rare earth element distributions in deep-sea brine sediments

2014

Abstract. Sediments collected from hypersaline and anoxic deep-sea basins in the eastern Mediterranean (Thetis, Kryos, Medee, and Tyro) were characterised in terms of their mineralogical composition, the distributions of rare earth elements (REE), Zr, and Hf and their content of microbial DNA. We identified two major mineralogical fractions: one fraction of detritic origin was composed of quartz, gypsum, and low-Mg calcite bioclasts (with 0 < Mg < 0.07%) and another fraction of authigenic origin constituted of halite, dolomite, high-Mg calcite (with a Mg content of up to 22%) and rare bischofite and showed a textural evidence of microbial assemblages. We found that in the Medee and Ty…

Electronic microdiffraction study of structural modifications resulting from the dehydration of gypsum. Prediction of the microstructure of resulting…

2001

Abstract Endothermic decomposition reactions (solid 1→solid 2+gas) generally affect only part of the inter-atomic bonds of the solid 1 structure. In consequence, the morphology and external dimensions of particles remain unchanged (the particles of solid 2 are referred to as pseudomorphs of those of solid 1). The gas release normally leads to a decrease of the molar volume of the precursor solid, resulting in cracking and formation of intra-particle porosity. This work deals with such a reaction: the dehydration of gypsum into sub-hydrated and anhydrous phases. Ultrathin (010) gypsum cleaved plates have been dehydrated under controlled conditions and studied by electron microdiffraction. Al…