Literatura académica sobre el tema "Basque-Cantabrian Basin"

The Basque-Cantabrian junction corresponds to an inverted rift accommodation zone at the limit between the former hyperextended Pyrenean and Cantabrian rift segments. The recognition of an inherited rift segment boundary allows to investigate the reactivation associated with large-scale rift segmentation in an orogenic system. We use criteria from published field observations and seismic data to propose a new map of rift domains for the Basque-Cantabrian junction. We also provide balanced cross-sections that allow to define the along-strike architecture associated with segmentation during rifting and subsequent Alpine reactivation. Based on these results, this study aims to characterize and identify reactivated and newly formed structures during inversion of two rift segments and its intermitted segment boundary. It also aims to describe the timing of thin-skinned and thick-skinned deformation associated with the inversion of segmented rift systems. During convergence, two phases have been recognized within the rift segment (eastern Mauléon basin). The Late Cretaceous to Paleocene underthrusting/subduction phase was mostly governed by thin-skinned deformation that reactivated the former hyperextended domains and the supra-salt sedimentary cover. The Eocene to Miocene collisional phase, controlled by thick-skinned deformation that took place once necking domains collided and formed an orogenic wedge. At the rift segment boundary, the underthrusting/subduction phase was already controlled by thick-skinned deformation due to the formation of shortcutting thrust faults at the termination of overlapping V-shaped rift segments. This led to the formation of a proto-wedge composed of the Basque massifs. We suggest that this proto-wedge is responsible for the preservation of pre-Alpine structures in the Basque massifs and for the emplacement of subcontinental mantle rocks at a crustal level beneath the western Mauléon basin. These results argue for a first order cylindrical orogenic architecture from the Central Pyrenean segment to the Cantabrian segment (up to the Santander transfer zone) despite rift segmentation. They also highlight the control of 3D rift-inheritance for the initial phase of orogenic evolution and for the local architecture of mountain belts.

Abstract The northern margin of the Basque-Cantabrian Basin was analysed combining stratigraphic and structural data from both surface and subsurface together with reflectance of vitrinite data from oil wells. The use of cross-section balancing techniques in addition to thermal modelling enabled us to reconstruct the tectonic, burial and thermal evolutions of the basin margin as well as those of the Landes High to the N in two different periods. The section restoration at the end of the Cretaceous shows a northern basin margin structure influenced by evaporites related to south-dipping normal faults. The reconstruction in middle Eocene times yielded up to 1 800 m of Paleocene-middle Eocene deposits on top of the basin margin. Subsequent tectonic inversion related to the Pyrenean compression led to the north-directed thrusting of basement units and to the formation of thrust slices or inverted folds in the cover along the northern margin of the basin. Tectonic subsidence analysis together with maturity data provided evidence that oil was generated in the basin during the late syn-rift and post-rift stages in the Late Cretaceous and became overmature during the period of incipient inversion after 55 Ma. In the autochthonous Landes High, the oil was generated after the tectonic inversion period 37 Ma.

This contribution presents the analysis of a data set that was put together in the PhD thesis of Jordi Miró which is part of the OROGEN Project. The Basque – Cantabrian Pyrenees, that are the focus of this report, have been extensively studied over the last years. Several open debates in the Earth Science community aroused from this realm regarding the formation and reactivation of rift domains and formation of fold and thrust belts. This report summarizes the main tectonic models proposed to explain both the extension and reactivation history over this area and compile a series of data to consider for further discussions and interpretations. This report includes a thematic map of the Basque – Cantabrian Pyrenees showing an analysis of the tectono-stratigraphic evolution of the area. The map covers an area of more than 33 000 km2 and is a graphic representation of the geology of the region based on a large geodatabase including previous published maps and field observations. A composite reflection seismic line crossing the entire Basque – Cantabrian Pyrenees from the Ebro foreland basin to the offshore Landes High is also presented. This section enables to present a continuous dataset along the entire area with the projection of few drill holes, which are presented with the stratigraphic logs following the same tectono-stratigraphic legend obtained from the previous analysis. The main goal of this data report is to provide a coherent and complete dataset to the community, which enables to propose, discuss and test some of the new concepts related to the formation and reactivation of rifted margins. This data report is complementary to the contributions of Lescoutre and Manatschal (2020) and Cadenas et al. (in prep) that are part of the same special volume.

The Paleogene experienced the most profound climatic shift of the past 65 million years of Earth history, Earth’s climate changing from a ‘greenhouse’ in the early Paleocene, to an ‘icehouse’ in the Oligocene. This transition resulted in significant re-organization of oceanic circulation, marine communities, and biogeochemical cycles. Particularly, climate changes occurred during the Eocene are forced (or thought to be forced) by variations of orbital parameters, especially by precession (21ky) and eccentricity (100ky), which can be detected by biotic proxies, like planktonic foraminifera, calcareous nannofossils and dinoflagellates (e.g., variation in their diversity, abundance and size), in hemipelagic and shallow waters. The high abundance of calcareous nannofossils in pelagic marine sediments, makes this group one of the most useful tools to perform biostratigraphic, paleoecologic and paleoclimatic studies. Calcareous nannofossils, showing high evolutionary rate, result to be a good biostratigraphic marker, particularly for Cenozoic, when they reach high diversification. In this PhD thesis, I investigate the relationships between orbital parameters and the variation of calcareous nannofossil abundances, expressed in eccentricity cycles of three different stratigraphic successions in the Basque-Cantabrian Basin (Spain): the Sopelana (early Ypresian), the Gorrondatxe (upper Ypresian) and the Oyambre sections (upper Lutetian). Most of the studies applying such an approach, are focused on the Neogene and Quaternary, and only few studies have been carried out in older Cretaceous and Jurassic records. Up to now, no detailed studies have been performed with the aim to investigate precession and eccentricity cycles and their forcing on calcareous nannofossil aassemblages during the Eocene. The three analyzed sections are constituted by rhythmic alternations of marls and limestones. A depositional-sedimentological model has been previously proposed for the three studied sections, on the base of geochemical proxies variation (CaCO3 content, Oxygen and Carbon isotopes). For the Oyambre and Gorrondatxe sections, a detailed biostratigraphy was already present, and the role of orbital forcing on sedimentation had been already highlighted by previous studies, while, for the Sopelana section there was a lack of this information. Concerning the Sopelana section (Chapter 2), before analysing the influence of precession and eccentricity forcing on calcareous nannofossil abundances, I provide a detailed nannofossil biostratigraphy, and, by means of spectral analysis on CaCO3 record, I highlight the role of the precession cycle in driving the deposition of marl-limestone couplets, and the effect of the eccentricity cycles on the sedimentation of bundles (each of which is composed by five marl- limestone couplets). The variation of calcareous nannofossil abundances induced by orbital forcing has been investigated in Chapter 3. The statistical analyses (implemented with Principal Component Analysis and Cluster methods), based on the variation of calcareous nannofossil abundances, carried out in the Sopelana, Oyambre and Gorrondatxe sections, confirm the previous sedimentological models, adding new information regarding the sedimentary environments during the Eocene in the Basque-Cantabrian Basin. The performed analyses indicate that the major calcareous nannofossil assemblages variations occur at the maximum eccentricity, in correspondence of which we observe a decrease in oligotrophic and stable environments taxa and an increase in eutrophic and low salinity taxa. These observations confirm that the maximum eccentricity corresponds to the maximum seasonality, leading to an increase in nutrients supply from continents and a higher water mixing (upwelling). A further work has been performed in the framework of the studies for the definition of the GSSP, considering that for the Paleogene two GSSPs are still pending (i.e., the base of Bartonian, middle Eocene, and the Priabonian, middle-upper Eocene). In our work, we focus on the definition of the Bartonian Stage. In Chapter 4, I report the results of a multidisciplinary study based on calcareous nannofossil, dinoflagellate, larger and smaller benthic foraminifera and magnetostratigraphy to assess potential correlations and placements for the Lutetian/Bartonian boundary. The Bartonian unit stratotype is located at the Barton coastal section (Hampshire Basin, UK). In this work, I study the parastratotype section, located 7 km away at Alum Bay, since it shows a better exposure. Basing on the obtained results, the Alum bay section is within the nannoplankton Zones CNE14 and CNE15. The Base of Rhombodinium draco, (dinoflagellate), an important and correlatable event in the Tethys domain, is recognized within the section, which also coincides with the acme of N. prestwichianus (formerly indicated as the base of the Bartonian Stage in the Barton area), both of which are correlated with nannoplankton Zone NP16, spanning the upper Lutetian and lower Bartonian. The palaeomagnetic correlation with calcareous nannofossil data allows to assign the normal Chron at the base of the section to C19n, considered an approximation for the base of the Bartonian Stage according to the Geological Time Scale. The remaining portion of the section correlates to C18n and C18r. All analyses, therefore, support that the section is lower Bartonian in age, with the palaeomagnetic data indicating that the first 5 m of the section also contains the Upper Lutetian.