Vol.:(0123456789) 1 3 Carbonates and Evaporites https://doi.org/10.1007/s13146-019-00516-0 ORIGINAL ARTICLE Messinian twinned selenite from the Catanzaro Trough, Calabria, Southern Italy: field, petrographic and fluid inclusion perspectives A. Costanzo 1  · M. Cipriani 2  · M. Feely 1  · G. Cianflone 3  · R. Dominici 2,3 Accepted: 2 July 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Field, petrographic and fluid inclusions (FIs) studies are used to investigate the formation of Miocene twinned selenite crystals from the Catanzaro Trough (Calabria, Southern Italy). The selenite was formed during the Messinian salinity crisis (MSC) (~ 6 Ma) and is classified into three facies: giant selenite, banded selenite and massive curvilinear selenite. Petro- graphic studies revealed the presence of alternating growth intervals (i.e. cloudy and clear intervals) in the selenite crystals that are occasionally separated by transition zones (intermediate interval). The giant selenite facies has cloudy intervals rich in primary FIs and organic matter; transition zones with lower abundances of FIs and organic matter have been observed, while clear zones are devoid of FIs. The banded selenite facies has cloudy and clear zones and relatively low abundances of organic matter. The massive selenite facies has cloudy zones with abundant primary FIs and organic matter and clear zones with low abundances of FIs and organic matter. These transition zones may have formed in response to daily or seasonal climate change oscillations, which in turn triggered alternations in selenite growth rates, in tandem with variations in biologi- cal activity and salinities. Microthermometric analyses have highlighted a salinity range between 0.18 and 11.34 eq. wt% NaCl. This indicates that the selenite precipitated from brines with a significant proportion of nonmarine waters. This study helps to place the Calabrian selenite into the interpretive framework of the MSC. The results of this study will contribute to a better understanding of the sedimentary processes active during the Messinian evolution of the northeastern sector of the Catanzaro Trough. Keywords Evaporites · Fluid inclusions · Selenite · Organic matter · Catanzaro Trough Introduction During the Messinian stage (5.96–5.33 Ma—Hsü et al. 1977; Krijgsman et al. 1999; Lugli et al. 2015), a catastrophic and unique event had been occurred in the Mediterranean basin and is known as the Messinian salinity crisis (MSC) (Fau- quette et al. 2006). This event caused the deposition of kilo- metric-scale evaporite units. Over the years, the origin of the MSC has been subject of much scientific debate focussed on the following genetic models: deep desiccated basin model (Hsü et al. 1973); shallow water desiccated basin model (Nesteroff 1973) and deep non-desiccated basin model (Selli 1973). In the early 90s, a series of studies proposed funda- mental modifications to the “deep desiccated basin model” (Suc and Bessais 1990; Benson et al. 1991; Gautier et al. 1994; Butler et al. 1995; Clauzon et al. 1996; Riding et al. 1998; Krijgsman et al. 1999; Rouchy and Caruso 2006). In 2008, the Mediterranean Sciences Commission (CIESM) have proposed a new desiccated (marginal basin) and non- desiccated (deep basin) model that was then discussed by several authors, e.g. Lugli et al. (2015) and Roveri et al. (2016). To date, after more than 40 years of studies, the origin of the MSC is still a matter of much scientific debate. Detailed studies of evaporite formations around the Medi- terranean area are essential for understanding the deposi- tional processes operating in the sedimentary basins and for reconstructing their paleo-environments since their genesis is related to regional and climatic events (Warren 2016). Recent studies have shown that by integrating facies analyses * A. Costanzo alessandra.costanzo@nuigalway.ie 1 Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Galway, Ireland 2 Department of Biology, Ecology and Earth Science, University of Calabria, Rende, Italy 3 E3-EalCUBO (Environment, Earth and Engineering) Start-up, University of Calabria, Rende, Italy