Cretaceous ammonites from Fuerteventura, Canary Islands

Mesozoic deep-water sediments occurring on the island of Fuerteventura were deposited near the continent-ocean boundary adjacent to the African margin. During Tertiary times, they were uplifted and intruded by ultramafic, mafic and alkaline plutons and dykes and are now exposed as part of the ‘Basal Complex' of the island. These sediments reflect more or less continuous hemipelagic and turbiditic deposition during most of Jurassic and Cretaceous times. Two ammonites, described in this paper, document a Valanginian to Hauterivian age for part of the Lower Cretaceous siliciclastic turbidites, and a latest Albian to early Cenomanian age for part of the Upper Cretaceous hemipelagic limestone

Presentazione di una nuova teoria sulla valutazione del rischio e concetto di utilità, ovvero traduzione, con breve introduzione, del saggio (1738) Specimen Theoriae Novae de Mensura Sortis di Daniel Bernoulli

Come noto nella teoria delle decisioni il valore atteso di una particolare scelta non può essere sempre preso come criterio per determinare la decisione ottimale dal punto di vista razionale. Daniel Bernoulli in una fortunata memoria scritta nel 1731 e contenuta nel volume dei Commentarii Academiae Scientiarum Imperialis Petropolitanae pubblicato nel 1738, per primo suggerì di utilizzare in luogo del valore atteso un valore morale o utilità attesa che una persona è disposta a spendere e che dipende dal patrimonio che possiede. La proposta di Bernoulli ha avuto grandi influenza ed eco, fino ai nostri giorni, in davvero molte discipline e diversi settori di ricerca. In particolare la prospettiva aperta dal saggio è alla base del cosiddetto approccio utilitarista, sia in filosofia che in politica ed economia, per il quale ogni decisione individuale dovrebbe essere ispirata dalla necessità di massimizzare la propria utilità attesa e l’insieme delle decisioni individuali dovrebbe andare nella direzione della massimizzazione del benessere collettivo. Senza inoltrarci qui in una discussione di questi od altri importanti aspetti, riassumiamo prima brevemente l’idea di Bernoulli ed il contesto in cui fu concepita e presentiamo poi la traduzione integrale del suo articolo dall’originale latino

Miocene shallow-water limestones from São Nicolau (Cabo Verde): Caribbean-type benthic fauna and time constraints for volcanism

Shallow-water limestones of presumed Late Cretaceous and Eocene age, interbedded with basaltic lavas, were described by earlier authors from São Nicolau in the northwestern part of the Cabo Verde archipelago. If confirmed, these ages would imply late Mesozoic shallow-marine and subaerial volcanic activity in the Cabo Verde archipelago, and document a geological history very different from that known so far from other Cabo Verde Islands, from which no subaerial volcanic activity before the mid-Cenozoic is known. Our re-investigation of the foraminiferal fauna indicates a Late Miocene age for the presumed Late Cretaceous and Eocene limestones. The hypothesis of a long-lived hot spot, active by the Early Cretaceous, and of a major island-building stage in the Cabo Verde Islands during this period, is therefore not supported by the present bio- or chronostratigraphic dat

Volcanic ash layers in the Upper Cretaceous of the Central Apennines and a numerical age for the early Campanian

At Montagna della Maiella and at Gola del Furlo (central Apennines) two discrete layers of bentonic clay are intercalated within the pelagic (Furlo) and turbiditic/pelagic limestones (Maiella) of the Upper Cretaceous basinal succession of the Umbrian basin (Scaglia facies). The bentonite layers are dated by planktonic foraminifera to the Globotruncanita elevata zone, early Campanian, and by calcareous nannofossils to the Aspidolithus parcus zone (CC 18); they fall into the reversed interval of chron 33. Detailed correlation shows the layers to be of exactly the same age. The upper layer is dated by U/Pb on magmatic zircons to 81.67±0.21Ma, an age compatible with the Cretaceous time-scale of Obradovich. The mineralogy of the bentonitic clays is almost pure montmorillonite and contrasts sharply with the clay mineral assemblage of the enclosing pelagic and turbiditic limestones, which is dominated by soil-derived smectite and illite in different proportions. The bentonite seams are interpreted as the submarine alteration products of wind-borne volcanic ashes. They can be followed with only minor changes in thickness over 200km and must be derived from distant volcanic sources and related to extreme volcanic events. A possible source area is present in the Dinarides where Upper Cretaceous subduction-related magmatic rocks are widesprea

The Alpine-Carpathian-Dinaridic orogenic system: correlation and evolution of tectonic units

A correlation of tectonic units of the Alpine-Carpathian-Dinaridic system of orogens, including the substrate of the Pannonian and Transylvanian basins, is presented in the form of a map. Combined with a series of crustal-scale cross sections this correlation of tectonic units yields a clearer picture of the three-dimensional architecture of this system of orogens that owes its considerable complexity to multiple overprinting of earlier by younger deformations. The synthesis advanced here indicates that none of the branches of the Alpine Tethys and Neotethys extended eastward into the Dobrogea Orogen. Instead, the main branch of the Alpine Tethys linked up with the Meliata-Maliac-Vardar branch of the Neotethys into the area of the present-day Inner Dinarides. More easterly and subsidiary branches of the Alpine Tethys separated Tisza completely, and Dacia partially, from the European continent. Remnants of the Triassic parts of Neotethys (Meliata-Maliac) are preserved only as ophiolitic mélanges present below obducted Jurassic Neotethyan (Vardar) ophiolites. The opening of the Alpine Tethys was largely contemporaneous with the Latest Jurassic to Early Cretaceous obduction of parts of the Jurassic Vardar ophiolites. Closure of the Meliata-Maliac Ocean in the Alps and West Carpathians led to Cretaceous-age orogeny associated with an eclogitic overprint of the adjacent continental margin. The Triassic Meliata-Maliac and Jurassic Western and Eastern Vardar ophiolites were derived from one single branch of Neotethys: the Meliata-Maliac-Vardar Ocean. Complex geometries resulting from out-of-sequence thrusting during Cretaceous and Cenozoic orogenic phases underlay a variety of multi-ocean hypotheses, that were advanced in the literature and that we regard as incompatible with the field evidence. The present-day configuration of tectonic units suggests that a former connection between ophiolitic units in West Carpathians and Dinarides was disrupted by substantial Miocene-age dislocations along the Mid-Hungarian Fault Zone, hiding a former lateral change in subduction polarity between West Carpathians and Dinarides. The SW-facing Dinaridic Orogen, mainly structured in Cretaceous and Palaeogene times, was juxtaposed with the Tisza and Dacia Mega-Units along a NW-dipping suture (Sava Zone) in latest Cretaceous to Palaeogene times. The Dacia Mega-Unit (East and South Carpathian Orogen, including the Carpatho-Balkan Orogen and the Biharia nappe system of the Apuseni Mountains), was essentially consolidated by E-facing nappe stacking during an Early Cretaceous orogeny, while the adjacent Tisza Mega-Unit formed by NW-directed thrusting (in present-day coordinates) in Late Cretaceous times. The polyphase and multi-directional Cretaceous to Neogene deformation history of the Dinarides was preceded by the obduction of Vardar ophiolites onto to the Adriatic margin (Western Vardar Ophiolitic Unit) and parts of the European margin (Eastern Vardar Ophiolitic Unit) during Late Jurassic to Early Cretaceous time