http://hdl.handle.net/2122/235 Search the Channel search http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/4526 Title: The Bajo Segura Basin (SE Spain): implications for the Messinian Salinity Crisis in the Mediterranean margins <br/> <br/>Authors: Soria, J. M.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Caracuel, J. E.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Corbí, H.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Lancis, C.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Tent-Manclús, J. E.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain; Yébenes, A.; Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, Apdo. Correos 99, 03080 Alicante, Spain <br/> <br/>Abstract: The analysis of the Messinian and Pliocene stratigraphy of the Bajo Segura Basin (a marginal basin of the western Mediterranean) has revealed three synthems deposited in a high sea-level context: T-MI (late Tortonian-Messinian), MII (Messinian), and P (early Pliocene), bounded by two lowstand erosional surfaces (intra-Messinian and end-Messinian unconformities). With respect to the salinity crisis, we propose the following series of events: 1) pre-evaporitic or pre-crisis phase (T-MI synthem); 2) first sea-level fall and subaerial exposure (intra-Messinian unconformity), possibly related to the precipitation of the Lower Evaporites; 3) syn-evaporitic phase (MII synthem), recorded both by selenitic gypsum (Upper Evaporites) as well as by lagoon deposits (Lago-Mare); 4) second sea-level fall and subaerial exposure (end-Messinian unconformity), characterized by deeply incised palaeovalleys; and 5) postevaporitic or post-crisis phase (P synthem), which coincides with the definitive restoration of open marine conditions in the basin. A combined biostratigraphic and magnetostratigraphic study revealed that all the events linked to the salinity crisis (from the end of the pre-evaporitic phase to the beginning of the post-evaporitic phase) occurred within the chron C3r (c. 5.9-5.2 Ma). http://hdl.handle.net/2122/4463 Title: Paleomagnetic investigations on the Pleistocene lacustrine sequence of Piànico-Sèllere (northern Italy) <br/> <br/>Authors: Scardia, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia; Muttoni, G.; Universita' di Milano <br/> <br/>Abstract: The Piànico-Sèllere is a lacustrine succession from northern Italy that records a sequence of climatic transitions across two Pleistocene glacial stages. The intervening interglacial stage is represented by well-preserved varves with calcitic (summer) and clastic (winter) laminae. There is a tight coupling between climate-driven lithologic changes and magnetic susceptibility variations, and stable paleomagnetic components were retrieved from all investigated lithologies including the largely diamagnetic calcite varves. These components were used to delineate a sequence of magnetic polarity reversals that was interpreted as a record of excursions of the Earth’s magnetic field. Comparison of the magnetostratigraphic results with previously published data allows discussion of two possible models which have generated controversy regarding the age of the Piànico Formation. The data indicates that the Piànico Formation magnetostratigraphy correlates to geomagnetic field excursions across the Brunhes/Matuyama transition, and consequently the Piànico interglacial correlates to marine isotope stage 19. This correlation option is substantially consistent with K-Ar radiometric age estimates recently obtained from a tepha layer interbedded in the Piànico Formation. The alternative option, considering the Piànico interglacial correlative to marine isotope stage 11 within the Brunhes Chron as supported by tephrochronological dating reported in the literature, is not supported by the magnetostratigraphic results. http://hdl.handle.net/2122/4438 Title: Characterization and astronomically calibrated age of the first occurrence of Turborotalia frontosa in the Gorrondatxe section, a prospective Lutetian GSSP: implications for the Eocene time scale <br/> <br/>Authors: Payros, A.; Department of Stratigraphy and Palaeontology, Faculty of Science and Technology, University of the Basque Country, PO Box 644, E-48080 Bilbao, Spain; Orue-Etxebarria, J.; Department of Stratigraphy and Palaeontology, Faculty of Science and Technology, University of the Basque Country, PO Box 644, E-48080 Bilbao, Spain; Bernaola, G.; Departamento de Ingeniería Minera y Metalúrgica y Ciencias de los Materiales, Escuela Universitaria de Ingeniería Técnica de Minas y Obras Públicas, University of the Basque Country, Beurko Muinoa s/n, E-48901 Barakaldo, Spain; Apellaniz, E.; Department of Stratigraphy and Palaeontology, Faculty of Science and Technology, University of the Basque Country, PO Box 644, E-48080 Bilbao, Spain; Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Tosquella, J.; Department of Geodynamics and Palaeontology, Faculty of Experimental Sciences, University of Huelva, Campus del Carmen, Avenida de las Fuerzas Armadas s/n, E-21071 Huelva, Spain; Caballero, F.; Department of Stratigraphy and Palaeontology, Faculty of Science and Technology, University of the Basque Country, PO Box 644, E-48080 Bilbao, Spain <br/> <br/>Abstract: The Gorrondatxe section, a prospective Lutetian Global Stratotype Section and Point (GSSP), has recently been used as the master reference section to reassess the correlation between Eocene magnetostratigraphic and calcareous planktonic biostratigraphic scales. However, the exact calibration of some events remained ill defined, as they were thought to be missing in Gorrondatxe due to a fault. The most important missing events were the first occurrence of the planktonic foraminifera Turborotalia frontosa and the C22n/C21r chron boundary. Either might be a reliable correlation criterion for the Ypresian/Lutetian boundary, as both approach the age of the original Lutetian Stratotype. New studies allowed the identification of the former event 9 m above the Gorrondatxe fault, within magnetic polarity Chron C21r and calcareous nannofossil Zone CP12a. Distinctive test features that characterize the most primitive morphotype of T. frontosa are described. Despite the high turbidite content, recurrent pelagic limestone–marl couplets and bundles occur, whose formation was driven by precession and eccentricity astronomical cycles. The first occurrence of T. frontosa was found 27 couplets and 5.5 bundles (60 m) below the first occurrence of the calcareous nannofossil Blackites inflatus, which is dated at 48 Ma. Hence, the age of the first occurrence of T. frontosa is estimated at 48.55 Ma, confirming that it is the most suitable planktonic foraminiferal correlation criterion for the Ypresian/Lutetian boundary. These results show that the stratigraphic interval missing due to the Gorrondatxe fault cannot be greater than a few metres and reinforce the value of this section as a prospective Lutetian GSSP. http://hdl.handle.net/2122/4130 Title: ‘‘Earliest Zanclean age for the Colombacci and uppermost Di Tetto formations of the « latest Messinian » northern Apennines: New palaeoenvironmental data from the Maccarone section (Marche Province, Italy)’’ by Popescu et al. (2007) Geobios 40 (359–373) <br/> <br/>Authors: Roveri, M.; Dipartimento di Scienze della Terra, Università di Parma, Via G.P. Usberti, 157/A, 43100 Parma, Italy; Bertini, A.; Dipartimento di Scienze della Terra, Università di Firenze, Via La Pira 4, 50121 Firenze, Italy; Cipollari, P.; Dipartimento di Scienze Geologiche, Università Roma-Tre, L.go S. Leonardo Murialdo 1, 00146 Roma, Italy; Cosentino, D.; Dipartimento di Scienze Geologiche, Università Roma-Tre, L.go S. Leonardo Murialdo 1, 00146 Roma, Italy; Di Stefano, A.; Dipartimento di Scienze Geologiche, Università di Catania, Corso Italia 55, 95129 Catania, Italy; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Gennari, R.; Dipartimento di Scienze della Terra, Università di Parma, Via G.P. Usberti, 157/A, 43100 Parma, Italy; Gliozzi, E.; Dipartimento di Scienze Geologiche, Università Roma-Tre, L.go S. Leonardo Murialdo 1, 00146 Roma, Italy; Grossi, F.; Dipartimento di Scienze Geologiche, Università Roma-Tre, L.go S. Leonardo Murialdo 1, 00146 Roma, Italy; Iaccarino, S.; Dipartimento di Scienze della Terra, Università di Parma, Via G.P. Usberti, 157/A, 43100 Parma, Italy; Lugli, S.; Dipartimento di Scienze della Terra, Università di Modena e Reggio Emilia, Piazza S. Eufemia 19, 41100 Modena, Italy; Manzi, V.; Dipartimento di Scienze della Terra, Università di Parma, Via G.P. Usberti, 157/A, 43100 Parma, Italy <br/> <br/>Abstract: Two possible alternative interpretations of the claimed Zanclean age (Popescu et al., 2007) of two historical lithostratigraphic units of the Northern Apennines, usually referred to as Late Messinian in age and recording the so called Lagomare final event of the Messinian salinity crisis (MSC), are here discussed. The wrong age attribution of the Colombacci and "tetto" Fms. is ruled out based on data from the Maccarone and other sections showing that the Colombacci-Argille Azzurre Fm. boundary is basin wide synchronous and coincident with the Miocene-Pliocene boundary as far as it has been formally defined in the Eraclea Minoa GSSP. Alternatively, the opportunity of emending the Zanclean GSSP to a stratigraphically lower horizon recording the first evidence of marine influences in the Mediterranean following the MSC peak, seems not suitable, as (1) the marine signature of uppermost Messinian deposits is weak and still controversial and (2) no significant bio- and magnetostratigraphic events, well chronologically defined and recognizable at a global scale appear to be available to such a purpose.