Palaeoenvironments of the Mediterranean Basin at the Messinian hypersaline/hyposaline transition: evidence from natural radioactivity and microfacies of post-evaporitic successions of the Adriatic sub-basin

Abstract

At the end of the Messinian salinity crisis, changes in the\ud palaeoceanography and palaeoclimate induced a transition\ud from hypersaline to hyposaline conditions in the Mediterranean\ud water body. Detailed investigation of natural radioactivity and\ud microfacies analyses of two early post-evaporitic Messinian\ud sections show that the transition occurred in poorly oxygenated\ud and well-stratified water masses. These transitional\ud deposits, which mainly consist of marls and CaCO3-rich\ud horizons, are generally well laminated and totally barren\ud in benthic and planktonic fauna. The presence of barite, small\ud (5–8 lm) authigenic framboidal pyrite, and high values of U\ud indicate persistent anoxic conditions during the early postevaporitic\ud Messinian stage in the Adriatic sub-basin of the\ud Mediterranean Sea. The presence of post-evaporitic welllaminated\ud barren deposits from both Mediterranean borderland\ud sections and ODP sites suggests that these anoxic\ud conditions extended to other sub-basins of the Mediterranean\ud region

Subsurface seepage dynamics and flow types in a Messinian paleoseep system (Maiella Mts., Central Italy)

“…Similar to the major authigenic components of the Flowmobilized Sediments, also the flow-textured sediments in which they are included (flow-mobilized pelites) show a very similar δ 13 C signature Supplemental material Table SM1c), suggesting that also their minor carbonate fraction mostly precipitated as a result of similar processes of organic matter degradation. Such processes are consistent with both the anoxic environment settled during the lower postevaporitic phase of the Messinian Salinity Crisis (Sampalmieri et al, 2010) and the high flow rates, which prevented the microbial oxidation of methane from taking place. A few traces of strictly methanederived facies nonetheless also exist within the feeder channels, in the form of botryoidal aragonite.…”

“…1c, 2a) rest above ramp limestones and marls (Bolognano Formation) and are well known from both wells and outcrop data (Di Napoli Alliata, 1964;Crescenti et al, 1969Crescenti et al, , 2002Crescenti, 1975;Patacca et al, 1992;Cipollari et al, 1999;Cosentino et al, 2005Cosentino et al, , 2013Sampalmieri et al, 2008Sampalmieri et al, , 2010. In the NW Maiella sector they include pre-evaporitic euxinic blue clays, Lower Evaporites, Resedimented Lower Evaporites, and the lower-to-upper postevaporitic pelitic marls (Fig.…”

“…2a). Resedimented Lower Evaporites, together with marls and clayey marls associated with the "Brecciated Limestones" unit (sensu Iadanza et al, 2013), rest above the MES and constitute the lower post-evaporitic portion (p-ev1; Sampalmieri et al, 2008Sampalmieri et al, , 2010Cosentino et al, 2013). The upper post-evaporitic succession (p-ev2) in turn unconformably overlies the p-ev1 deposits through a younger erosional surface (MES2, Cipollari et al, 2013), and in the Maiella area it documents the occurrence of the late Messinian Lago-Mare oligohaline event (Cipollari et al, 1999;Gliozzi et al, 2002;Crescenti et al, 2002;Cosentino et al, 2005Grossi et al, 2008), correlatable to the Loxocorniculina djaffarovi zone (Carbonnel, 1978;Grossi et al, 2011).…”

Deep-seated hydrocarbons in the seep “Brecciated Limestones” of the Maiella area (Adriatic foreland basin): Evaporitic sealing and oil re-mobilization effects linked to the drawdown of the Messinian Salinity Crisis

“…The MSC, which was responsible for the deposition of the "Primary Lower Gypsum" and the post-evaporitic Lago-Mare succession in the area (Bonarelli, 1951;Di Napoli Alliata, 1964;Crescenti et al, 1969a, b;Catenacci, 1974;Clermontè and Geisler, 1977;Patacca et al, 1992;Cipollari et al, 1999Cipollari et al, , 2003Gliozzi et al, 2002;Crescenti et al, 2002;Centamore and Nisio, 2003;Cosentino et al, 2005Cosentino et al, , 2011Cosentino et al, , 2013Sampalmieri et al, 2008;Sampalmieri et al, 2010;Iadanza et al, 2013;Schildgen et al, 2014), was followed by the Early Pliocene flooding event that marked the end of the crisis and was responsible for the deposition of bathyal clays (MPL1-lower MPL2 biozones; Cipollari et al, 2003).…”

“…are extensively eroded by the MES and followed by a thin, discontinuous gypsarenite level and barren laminated sediments hosting the lower portion of the hydrocarbon-derived "Brecciated Limestones" (p-ev1; Fig. 2) (Sampalmieri et al, 2010;Cosentino et al, 2013;Iadanza et al, 2013). Laminated sediments that include the first occurrences of Paratethyan-affinity ostracoda (Grossi and Gliozzi, pers.…”