Datos paleomagnéticos del sustrato rocoso de la isla de Livingston (Península Antártica): implicaciones tectónicas en la evolución neógena

Se presentan resultados paleomagnéticos de la Fo rmación Miers Bluff y de los diques terciarios y andesitas de la Isla de Livingston (Islas Shetland del Sur, Península A n t á rtica). La mayoría de las rocas estudiadas son portadoras de magnetización estable, que reside en una fase de baja coercividad, probablemente Ti-Magnetita. La restitución tectónica progresiva de las direcciones de magnetización remanente característica revela que la magnetización en las turbiditas de la Fm. Miers Bluff fue adquirida después del plegamiento. Las direcciones medias de los diques y de la Fm. Miers Bluff no ofrecen una diferencia significativa, sugiriendo una misma edad para la magnetización. Se propone que el origen de la misma es una remagnetización de edad terciaria. Asimismo, la posición de los polos paleomagnéticos obtenidos sugiere un basculamiento tectónico que estaría relacionado con la apertura y extensión en el Estrecho de Bransfield.We report paleomagnetic results from the Miers Bluff Formation and Tertiary dykes and andesites in Livingston Island (South Shetland Islands, Antarctic Peninsula). Most of the samples carry stable magnetization, residing in a low coercivity phase, most likely (Ti)magnetite. Progressive untilting of the Characteristic Remanent Magnetization directions reveals that the magnetization of the turbidites (Miers Bluff Fm.) is post-folding. Miers Bluff and the dyke mean directions do not show any significant difference, suggesting the same magnetization age. Thus, a local Cenozoic remagnetization is proposed. Also, the paleomagnetic poles suggest a tectonic tilting that would explain the observed discrepancies between the produced paleopoles and the APWP for the Antarctic Peninsula

Integrated multi-stratigraphic study of the Coll de Terrers late Permian-Early Triassic continental succession from the Catalan Pyrenees (NE Iberian Peninsula): A geologic reference record for equatorial Pangaea

The most severe biotic crisis on Earth history occurred during the Permian-Triassic (PT) transition around 252 Ma. Whereas in the marine realm such extinction event is well-constrained, in terrestrial settings it is still poorly known, mainly due to the lack of suitable complete sections. This is utterly the case along the Western Tethys region, located at Pangaea's equator, where terrestrial successions are typically build-up of red beds often characterised by a significant erosive gap at the base of the Triassic strata. Henceforth, documenting potentially complete terrestrial successions along the PT transition becomes fundamental. Here, we document the exceptional Coll de Terrers area from the Catalan Pyrenees (NE Iberian Peninsula), for which a multidisciplinary research is conducted along the PT transition. The red-bed succession, located in a long E-W extended narrow rift system known as Pyrenean Basin, resulted from a continuous sedimentary deposition evolving from meandering (lower Upper Red Unit) to playa-lake/ephemeral lacustrine (upper Upper Red Unit) and again to meandering settings (Buntsandstein facies). Sedimentary continuity is suggested by preliminary cyclostratigraphic analysis that warrants further analysis. Our combined sedimentological, mineralogical and geochemical data infer a humid-semiarid-humid climatic trend across the studied succession. The uppermost Permian strata, deposited under an orbitally controlled monsoonal regime, yields a relatively diverse ichnoassemblage mainly composed of tetrapod footprints and arthropod trace fossils. Such fossils indicate appropriate life conditions and water presence in levels that also display desiccation structures. These levels alternate with barren intervals formed under dry conditions, being thus indicative of strong seasonality. All these features are correlated with those reported elsewhere in Gondwana and Laurasia, and suggest that the Permian-Triassic boundary might be recorded somewhere around the Buntsandstein base. Consequently, Coll de Terrers and the whole Catalan Pyrenees become key regions to investigate in detail the Permian extinction event and the Triassic ecosystems recovery

Preliminary integrated magnetostratigraphic and biostratigraphic correlation in the Miocene Lorca Basin (Murcia, SE Spain).

The Lorca basin is one of the Neogene basins OS South Eastern Spain. The infilling Tortonian-Messinian deposits are mainly composed OS marls and reach up to 1,200 m in thickness. A biostratigraphic survey OS these deposits, assisted by the determination OS the magnetic polarity reversal pattern Sor most OS these deposits (900 m), has enabled the Tortonian-Messinian chronostratigraphy to be precised. The close sampling space for biostratigraphic determination has enabled the accurate location OS Sour main biostratigraphic events than can be correlated with charactenstic events of the Mediterranean biostratigraphic Zones. In addition, the location OS the TortonianNessinian boundary has been accurately placed at some 150 m below the main gypsurn unit outcropping in the basin. The integrated bio-magnetostratigraphic data fiom the studied section allows a tentative interpretation OS the identified magnetozones. Thus, a correlation to the Geomagnetic Polarity Time Scale is presented for more than 900 m of pre-evaporite Miocene stratigraphic succession fiom the Lorca basin. Moreover, about 15' OS anticlockwise rotation has been detected. Its significance is evaluated in the basin geodynamic framework

Correlation of the Thanetian-Ilerdian turnover of larger foraminifera and the Paleocene-Eocene thermal maximum : confirming evidence from the Campo area (Pyrenees, Spain)

It has long been known that a major larger foraminifera turnover (LFT) occurred at the boundary between the Thanetian and Ilerdian stages, but its possible correlation with the Paleocene-Eocene thermal maximum (PETM) was unsuspected until the work of Baceta (1996), and has been controversial ever since. After summarizing the history of this controversy, we present information from three new sections that conclusively resolve the issue, all of them placed less than 2 km to the east of the classical Campo section in the southern Pyrenees. In these three sections, an up to 7 meter-thick intercalation of continental deposits rich in pedogenic carbonate nodules is sandwiched between uppermost Thanetian and lowermost Ilerdian shallow marine carbonates. The d13C composition of 42 pedogenic nodules collected from two of these sections (San Martín and La Cinglera) ranges between -11.4 and -14.3‰ and averages -12.9‰, values that conclusively represent the PETM and for the first time are recorded in sections where the LFT is clearly represented. Further, a high-resolution lithological correlation between Campo and the three new sections across the P-E interval unquestionably demonstrates that the lowermost marine beds with autochthonous specimens of Alveolina vredenburgi (a tell-tale of the LFT) are laterally interfingered -and are therefore coeval- with the nodule-bearing PETM continental deposits. On the basis of the new evidence, the temporal coincidence of the PETM and the LFT can no longer be doubted

Correlation of the Thanetian-Ilerdian turnover of larger foraminifera and the Paleocene-Eocene thermal maximum: confirming evidence from the Campo area (Pyrenees, Spain)

It has long been known that a major larger foraminifera turnover (LFT) occurred at the boundary between the Thanetian and Ilerdian stages, but its possible correlation with the Paleocene-Eocene thermal maximum (PETM) was unsuspected until the work of Baceta (1996), and has been controversial ever since. After summarizing the history of this controversy, we present information from three new sections that conclusively resolve the issue, all of them placed less than 2 km to the east of the classical Campo section in the southern Pyrenees. In these three sections, an up to 7 meter-thick intercalation of continental deposits rich in pedogenic carbonate nodules is sandwiched between uppermost Thanetian and lowermost Ilerdian shallow marine carbonates. The d13C composition of 42 pedogenic nodules collected from two of these sections (San Martín and La Cinglera) ranges between –11.4 and -14.3‰ and averages –12.9‰, values that conclusively represent the PETM and for the first time are recorded in sections where the LFT is clearly represented. Further, a high-resolution lithological correlation between Campo and the three new sections across the P-E interval unquestionably demonstrates that the lowermost marine beds with autochthonous specimens of Alveolina vredenburgi (a tell-tale of the LFT) are laterally interfingered –and are therefore coeval- with the nodule-bearing PETM continental deposits. On the basis of the new evidence, the temporal coincidence of the PETM and the LFT can no longer be doubted

The upper Maastrichtian dinosaur fossil record from the southern Pyrenees and its contribution to the topic of the Cretaceous–Palaeogene mass extinction event

In the present paper, the fossil record of the archosaurs (dinosaurs, crocodylomorphs and pterosaurs) of the southern Pyrenees before the Cretaceous–Palaeogene (K–Pg) transition is revised. On the basis of this fossil record, a well-dated succession of dinosaurs and other archosaurs is established within polarity magnetochrons C30 and C29r. Almost 150 sites with dinosaur remains have been identified, containing hadrosauroid ornithopods, titanosaur sauropods and theropods, as well as egg sites and tracks. Fossil remains of dinosaurs and other archosaurs are abundant in C29r, disappearing abruptly near the top of the “Lower Red Garumnian” unit of the Tremp Formation. Thus this should be located very close to, or coinciding with the K–Pg boundary. These data suggest that the disappearance of the dinosaurs and other archosaurs was geologically abrupt in the southern Pyrenees, but to date there is no incontrovertible evidence of the presence of the impact level that marks the Cretaceous–Palaeogene boundary. Interestingly, what is highlighted in the southern Pyrenees is that the vertebrate-rich upper Maastrichtian continental sites were replaced by similar sedimentological facies characterized by the virtual absence not only of dinosaurs but also of any vertebrate remain throughout the lower Palaeocene. This could mean that the Danian terrestrial ecosystems of the southern Pyrenees took longer than other areas of the world to recover their biodiversity after the K−Pg extinction event.Fil: Canudo, José I.. Universidad de Zaragoza. Facultad de Ciencias; EspañaFil: Oms, Oriol. Universitat Autònoma de Barcelona; EspañaFil: Vila, Bernat. Universidad de Zaragoza. Facultad de Ciencias; EspañaFil: Galobart, Àngel. Institut Català de Paleontologia Miquel Crusafont; España. Museu de la Conca Dellà; EspañaFil: Fondevilla, Víctor. Universitat Autònoma de Barcelona; EspañaFil: Puértolas Pascual, Eduardo. Universidad de Zaragoza. Facultad de Ciencias; EspañaFil: Garcia Sellés, Albert. Institut Català de Paleontologia Miquel Crusafont; EspañaFil: Cruzado Caballero, Penélope. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Dinarès Turell, Jaume. Istituto Nazionale di Geofisica e Vulcanologia; ItaliaFil: Vicens, Enric. Universitat Autònoma de Barcelona; EspañaFil: Castanera, Diego. Universidad de Zaragoza. Facultad de Ciencias; EspañaFil: Company, Julio. Universidad Politécnica de Valencia; EspañaFil: Burrel, Laura. Universitat Autònoma de Barcelona; EspañaFil: Estrada, Rita. Universitat Autònoma de Barcelona; EspañaFil: Marmi, Josep. Institut Català de Paleontologia Miquel Crusafont; EspañaFil: Blanco, Alejandro. Institut Català de Paleontologia Miquel Crusafont; Españ

The upper Maastrichtian dinosaur fossil record from the southern Pyrenees and its contribution to the topic of the Cretaceous Palaeogene mass extinction event

In the present paper, the fossil record of the archosaurs (dinosaurs, crocodylomorphs and pterosaurs) of the southern Pyrenees before the CretaceousePalaeogene (KePg) transition is revised. On the basis of this fossil record, a well-dated succession of dinosaurs and other archosaurs is established within polarity magnetochrons C30 and C29r. Almost 150 sites with dinosaur remains have been identified, containing hadrosauroid ornithopods, titanosaur sauropods and theropods, as well as egg sites and tracks. Fossil remains of dinosaurs and other archosaurs are abundant in C29r, disappearing abruptly near the top of the Lower Red Garumnian unit of the Tremp Formation. Thus this should be located very close to, or coinciding with the KePg boundary. These data suggest that the disappearance of the dinosaurs and other archosaurs was geologically abrupt in the southern Pyrenees, but to date there is no incontrovertible evidence of the presence of the impact level that marks the CretaceousePalaeogene boundary. Interestingly, what is highlighted in the southern Pyrenees is that the vertebrate-rich upper Maastrichtian continental sites were replaced by similar sedimentological facies characterized by the virtual absence not only of dinosaurs but also of any vertebrate remain throughout the lower Palaeocene. This could mean that the Danian terrestrial ecosystems of the southern Pyrenees took longer than other areas of the world to recover their biodiversity after the K Pg extinction event.This paper is a tribute to Prof. Nieves Lopez Martinez (deceased in 2010); some of the research included here was conducted under her guidance. This paper forms part of the projects CGL2014-53548-P, CGL2011-25581, CGL2011-30069-C02-01,02/BTE, subsidized by the Spanish Ministerio de Economia y Competitividad, the European Regional Development Fund, and the European Social Fund. Moreover, the Generalitat de Catalunya, the University of Zaragoza and the Government of Aragon, ("Grupos Consolidados" and "Direccion General de Patrimonio Cultural") funded the fieldwork. B. Vila acknowledges support from the Ministerio de Economia y Competitividad (Subprograma Juan de la Cierva MICINN-JDC, 2011). E. Puertolas is supported by the program Formacion del Profesorado Universitario (FPU) subsidized by the Spanish Ministerio de Educacion, Cultura y Deportes. V. Fondevilla is supported by the program Formacion del Personal Investigador (FPI, BES-2012-052366), subsidized by the Spanish Ministerio de Economia y Competitividad. A. Blanco is supported by a FI AGAUR grant from the DGR of the Generalitat de Catalunya (2013FI_B 01059). We thank David E. Fastovsky (Universitat Wien) and Hugues Alexandre Blain (Institut de Paleoecologia Humana i Evolucio Social) for their comments on the original manuscript during the peer-review process. Rupert Glasgow revised the English of the text.Canudo, JI.; Oms, O.; Vila, B.; Galobart, Á.; Fondevilla, V.; Puertolas-Pascual, E.; Sellés, AG.... (2015). The upper Maastrichtian dinosaur fossil record from the southern Pyrenees and its contribution to the topic of the Cretaceous Palaeogene mass extinction event. Cretaceous Research. 57:540-551. doi:10.1016/j.cretres.2015.06.013S5405515