Geologia dei Gessi di Brisighella e Rontana

L’area di Brisighella rappresenta un eccellente laboratorio naturale per comprendere la prima fase della crisi di salinità, lo straordinario evento geologico che nel Messiniano (Miocene superiore), tra 5.970.000 e 5.600.000 di anni fa, ha trasformato il bacino del Mediterraneo in una gigantesca salina inospitale per la maggior parte delle forme di vita. La crisi di salinità messiniana ha prodotto 16 strati di selenite della Vena del Gesso (Gessi Inferiori Primari) con cristalli lunghi fino a due metri che contengono fossilizzati al loro interno filamenti di cianobatteri. Appena terminata la deposizione del gesso l’area è stata coinvolta da importati eventi tettonici che hanno innescato enormi frane sottomarine provocando lo smembramento della formazione gessosa e la deposizione dei Gessi Inferiori Risedimentati. Abstract The Brisighella area is an excellent natural laboratory for understanding the first phase of the salinity crisis, the dramatic geological event that has turned the Mediterranean Sea into a giant salina inhospitable to most life forms during the Messinian (Upper Miocene), between 5.97 million and 5.6 million years ago. The Messinian salinity crisis has produced 16 layers of selenite Vena del Gesso (Primary Lower Gypsum) with crystals up to two meters tall containing fossilized filaments of cyanobacteria. As soon as the deposition of gypsum finished, the area has been affected by tectonic events that have triggered massive submarine landslides causing the dismantlement of the gypsum formation and the deposition of the Resedimented Lower Gypsum unit

High-frequency cyclicity in the Mediterranean Messinian evaporites: evidence for solar-lunar climate forcing

The deposition of varved sedimentary sequences is usually controlled by climate conditions. The study of two Late Miocene evaporite successions (one halite and the other gypsum) consisting of annual varves has been carried out to reconstruct the paleoclimatic and paleoenvironmental conditions existing during the acme of the Messinian salinity crisis, ~ 6 Ma, when thick evaporite deposits accumulated on the floor of the Mediterranean basin. Spectral analyses of these varved evaporitic successions reveal significant periodicity peaks at around 3-5, 9, 11-13, 20-27 and 50-100 yr. A comparison with modern precipitation data in the western Mediterranean shows that during the acme of the Messinian salinity crisis the climate was not in a permanent evaporitic stage, but in a dynamic situation where evaporite deposition was controlled by quasi-periodic climate oscillations with similarity to modern analogs including Quasi-Biennial Oscillation, El Ni\~no Southern Oscillation, and decadal to secular lunar- and solar-induced cycles. Particularly we found a significant quasi-decadal oscillation with a prominent 9-year peak that is commonly found also in modern temperature records and is present in the contemporary Atlantic Multidecadal Oscillation (AMO) index and Pacific Decadal Oscillation (PDO) index. These cyclicities are common to both ancient and modern climate records because they can be associated with solar and solar-lunar tidal cycles.Comment: 13 pages, 10 figures, 1 Tabl

The deep record of the Messinian salinity crisis: Evidence of a non-desiccated Mediterranean Sea

This research is focused on a complete reexamination of the evaporite facies present in all the cores that cut through the topmost deposits of the Messinian salinity crisis lying below the floor of the Mediterranean Sea (DSDP Legs 13 and 42A, ODP Legs 107 and 161). This review suggests that the uppermost evaporite units in both western and eastern deep Mediterranean basins consist mainly of clastic (gypsrudite, gypsarenite and gypsiltite) and fully subaqueous deposits (laminar gypsum, selenite and cumulate halite) that are partially affected by burial anhydritization and tectonic induced recrystallization. No unequivocal evidence of shallow water or even supratidal (sabkha) deposition is in evidence, suggesting that at the very last phase of the salinity crisis the Mediterranean Sea did not experience desiccation, but that deposition took place under permanent subaqueous conditions

Survival to amputation in pre-antibiotic era: a case study from a Longobard necropolis (6th-8th centuries AD)

The Longobard necropolis of Povegliano Veronese dates from the 6th to the 8th centuries AD. Among the 164 tombs excavated, the skeleton of an older male shows a well-healed amputated right forearm. The orientation of the forearm fracture suggests an angled cut by a single blow. Reasons why a forearm might be amputated include combat, medical intervention, and judicial punishment. As with other amputation cases reported in literature, this one exhibits both healing and osteoblastic response. We argue that the forelimb stump morphology suggests the use of a prosthesis. Moreover, dental modification of RI2 shows considerable wear and smoothing of the occlusal surface, which points to dental use in attaching the prosthesis to the limb. Other indications of how this individual adjusted to his amputated condition includes a slight change in the orientation of the right glenoid fossa surface, and thinning of right humeral cortical bone. This is a remarkable example in which an older male survived the loss of a forelimb in pre-antibiotic era. We link archaeological remains found in the tomb (buckle and knife) with the biological evidence to show how a combined bioarchaeological approach can provide a clearer interpretation of the life history of an individual

How dry was the Mediterranean during the Messinian salinity crisis?

The Messinian salinity crisis (MSC; 5.97\u20135.33 Ma) is an enigmatic episode of paleoceanographic change, when kilometers-thick evaporite units were deposited in the Mediterranean basin. It is generally accepted that during the MSC interval there was a dry climate in the Mediterranean region. It is difficult to assess how dry the climate was during the MSC because a modern analogue, in size and duration, is absent. Here we reconstruct hydrological changes in the Mediterranean basin during the three main MSC stages using excellently preserved biomarkers. We used the hydrogen isotopic composition of the long chain n-alkanes (\u3b4Dn-alkanes) to reconstruct the hydrological changes on the land adjacent to the Mediterranean Sea. Additionally, the \u3b4D of long-chain alkenones (\u3b4Dalkenones) is used to observe changes in the Mediterranean Sea water source. The \u3b4Dn-alkanes recorded during the deposition of Primary Lower Gypsum (stage 1) in Monte Tondo indicate a \u3b4D of the precipitation comparable to the present-day Mediterranean implying a similar hydrologic regime (indicated by experiments modelling the Miocene-Pliocene transition). Elevated \u3b4Dalkenones values from halite unit (stage 2) of the Realmonte mine are associated with kainite and giant polygons, consistent with presumably high evaporative conditions during halite deposition. The \u3b4Dn-alkanes recorded during the deposition of Upper Gypsum (stage 3) in Eraclea Minoa indicate a \u3b4Dprecipitation typical for much drier settings, similar to the Red Sea region. The relative contribution of the different alkenones from Eraclea Minoa is similar to the one observed in present-day marine settings suggesting that, during stage 3, connections to the open Ocean were likely maintained. However, the \u3b4Dalkenones records during deposition of the evaporites in Eraclea Minoa are similar to those synchronously registered in the Black Sea implying that a similar hydrologic regime, characterized by extended drought, covered large areas of southeastern Europe. Based on the \u3b4Dalkenones similarity and the Paratethys type of \ub4Lago Mare\ub4 fauna in the Mediterranean we speculate that the surface water during stage 3 was, at times, derived from the Black Sea

Paleo‐thermal constraints on the origin of native diagenetic sulfur in the Messinian evaporites : The Northern Apennines foreland basin case study (Italy)

This work has benefited from the equipment and frame-work of the COMP- HUB Initiative (University of Parma), funded by the Department of Excellence programme of the Italian Ministry for Education, University and Research (MIUR, 2018- 2022). This work has benefited from University of Roma Tre MIUR funds for the Department of Excellence. This work has benefited from the University of Parma FIL2016- 2018 responsible Professor Marco Roveri, University of Parma FIL2016- 2018 responsible Professor Vinicio Manzi, MIUR PhD scholarship 2016- 2019. Platte River Associates, Inc is kindly acknowledged for providing BasinMod2D® software for research purposes. Massimo Rossi (ENI S.p.A., Milano, Italy) is kindly acknowledged for his review of the manuscriptPeer reviewedPublisher PD

The Messinian salinity crisis in Cyprus: a further step towards a new stratigraphic framework for Eastern Mediterranean

A revised stratigraphic framework for the Messinian succession of Cyprus is proposed demonstrating that the three-stage model for the Messinian salinity crisis recently established for the Western Mediterranean also applies to the Eastern Mediterranean, at least for its marginal basins. This analysis is based on a multidisciplinary study of the Messinian evaporites and associated deposits exposed in the Polemi, Pissouri, Maroni/Psematismenos and Mesaoria basins. Here, we document for the first time that the base of the unit usually referred to the 'Lower Evaporites' in Cyprus does not actually correspond to the onset of the Messinian salinity crisis. The basal surface of this unit rather corresponds to a regional-scale unconformity, locally associated with an angular discordance, and is related to the erosion and resedimentation of primary evaporites deposited during the first stage of the Messinian salinity crisis. This evidence suggests that the 'Lower Evaporites' of the southern basins of Cyprus actually belong to the second stage of the Messinian salinity crisis; they can be thus ascribed to the Resedimented Lower Gypsum unit that was deposited between 5.6 and 5.5\ua0Ma and is possibly coeval to the halite deposited in the northern Mesaoria basin. Primary, in situ evaporites of the first stage of the Messinian salinity crisis were not preserved in Cyprus basins. Conversely, shallow-water primary evaporites deposited during the third stage of the Messinian salinity crisis are well preserved; these deposits can be regarded as the equivalent of the Upper Gypsum of Sicily. Our study documents that the Messinian stratigraphy shows many similarities between the Western and Eastern Mediterranean marginal basins, implying a common and likely coeval development of the Messinian salinity crisis. This could be reflected also in intermediate and deep-water basins; we infer that the Lower Evaporites seismic unit in the deep Eastern Mediterranean basins could well be mainly composed of clastic evaporites and that its base could correspond to the Messinian erosional surface

The Messinian salinity crisis: open problems and possible implications for Mediterranean petroleum systems

Abstract: A general agreement on what actually happened during the Messinian salinity crisis (MSC) has been reached in the minds of most geologists but, in the deepest settings of the Mediterranean Basin, the picture is still far from being finalized and several different scenarios for the crisis have been proposed, with different significant implications for hydrocarbon exploration. The currently accepted MSC paradigm of the ‘shallow-water deep-basin’ model, which implies high-amplitude sea-level oscillations (> 1500 m) of the Mediterranean up to its desiccation, is usually considered as fact. As a consequence, it is on this model that the implications of the MSC events on the Mediterranean petroleum systems are commonly based. In fact, an alternative, deep-water, non-desiccated scenario of the MSC is possible: it (i) implies the permanence of a large water body in the Mediterranean throughout the entire Messinian salinity crisis, but with strongly reduced Atlantic connections; and (ii) envisages a genetic link between Messinian erosion of the Mediterranean margins and deep brine development. In this work, we focus on the strong implications of an assessment of the petroleum systems of the Mediterranean and adjoining areas (e.g. the Black Sea Basin) that can be based on such a non-desiccated MSC scenario. In particular, the near-full basin model delivers a more realistic definition of Messinian source-rock generation and distribution, as well as of the magnitude of water-unloading processes and their effects on hydrocarbon accumulation