106 research outputs found

    Further evidence for a relatively high sea level during the penultimate interglacial: open-system U-series ages from La Marina (Alicante, East Spain)

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    The elevation and timing of high sea stands during Oxygen Isotope Stage (OIS) 7 are not as well constraíned as those of OIS 5e. Conflictíng values are reported from Medíterranean coastlines, and fossil dating is inaccurate because of ubiquitous open U-series systems. New morphostratigraphic data from La Marina (eastem Spain) supported by open-system U-series coral ages shed light on the maximum sea level duríng OIS 7. Fossil corals (Cladocora Caespitosa) underlying an OIS 5e marine unít yielded U-series ages from 178 ± (0 to 208 ± 1) ka (± 20σ n=7) with an outlier al 240 ± 18 ka. Mean open-system limit ages of 170 ± 10 (minimum age after correction for 234Th-230Th uptake) and 237 ± 20 ka (maximum ase after correction for 238U - 234U uptake) were calculated to have a probable age closer to the minimum value, for an assignment of OlS 7a or 7c. The occurrence of a warn-water "Senegalese" fauna (Strombus bubonius) in OIS5e and OIS 7 marine units confirms the arrival of tropical species to the Mediterranean before the last interglacial periodo Morpho-sedimentological and neotectonic studies suggest that the maximum paleo-sea level during OIS 7c or 7a was a few melers below that of OlS Se

    High resolution seismic stratigraphic analysis: An integrated approach to the subsurface geology of the SE Persian Gulf

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    Papers included in this dissertation: Paper 1: Farzadi, P. 2006a. The development of Middle Cretaceous carbonate platforms, Persian Gulf, Iran: Constraints from seismic stratigraphy, well and biostratigraphy. Petroleum Geoscience, 12, 59-68. Paper 2: Farzadi, P. 2006b. Seismic facies analysis based on 3D multi-attribute volume classification, Dariyan Formation, SE Persian Gulf. Journal of Petroleum Geology,29/2, 159-174. Paper 3: Farzadi, P. & Hesthammer, J. (Submitted 2006). Diagnosis of the Upper Cretaceous paleokarst and turbidite systems from the Iranian Persian Gulf using volume-based multiple seismic attribute analysis and pattern recognition. N.B.: Originally accepted for publication in the AAPG Bulletin, later rejected because the US government prohibits the publication of papers using Iranian government datasets. The manuscript has been re-submitted to Petroleum Geoscience. Paper 4: Farzadi, P. & Alaei, B. (Submitted 2006). Stratigraphic architecture of the Zagros Basin: towards an objective comparison of the Fold-Thrust Belt and Foreland provinces. Submitted to the Journal of Petroleum Geology; under consideration for a thematic issue. Presentation (at international meeting and on web): Farzadi, P. 2005. Stratal geometries of the Cretaceous carbonate systems: application of multiple volumes attributes analysis to 3-D seismic data from the Persian Gulf. At: Middle to Far East Carbonate Reservoirs: Exploration, Development and Exploitation. PESGB Carbonate conference, 15th & 16th Nov. 2005 London

    Crustal types and Tertiary tectonic evolution of the Alborán sea, western Mediterranean

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    Multichannel seismic reflection images across the transition between the east Alborán and the Algero-Balearic basins show how crustal thickness decreases from about 5 s two-way traveltime (TWTT, ∼15 km thick) in the west (east Alborán basin) to ∼2 s TWTT typical of oceanic crust (∼6 km thick) in the east (Algero-Balearic basin). We have differentiated three different crustal domains in this transition, mainly on the basis of crustal thickness and seismic signature. Boundaries between the three crustal domains are transitional and lack evidence for major faults. Tilted blocks related to extension are very scarce and all sampled basement outcrops are volcanic, suggesting a strong relationship between magmatism and crustal structure. Stratigraphic correlation of lithoseismic units with sedimentary units of southeastern Betic basins indicates that sediments onlap igneous basement approximately at 12 Ma in the eastern area and at 8 Ma in the western area. Linking seismic crustal structure with magmatic geochemical evidence suggests that the three differentiated crustal domains may represent, from west to east, thin continental crust modified by arc magmatism, magmatic-arc crust, and oceanic crust. Middle to late Miocene arc and oceanic crust formation in the east Alborán and Algero-Balearic basins, respectively, occurred during westward migration of the Gibraltar accretionary wedge and shortening in the Betic-Rif foreland basins. Arc magmatism and associated backarc oceanic crust formation were related to early to middle Miocene subduction and rollback of the Flysch Trough oceanic basement. Subduction of this narrow slab beneath the Alborán basin was coeval with collision of the Alborán domain with the Iberian and African passive margins and subsequent subcontinental-lithosphere edge delamination along the Betic-Rif margins

    Continuité ou discontinuité de sémentation marine mio-pliocène en Méditerranée occidentale. L'example du bassin de vera (Espagne méridionale) Continuity Or Discontinuity of Io-Pliocene Marine Sedimentation in the Western Mediterranean. Example of the Vera Basin (Southern Spain)

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    L'étude du bassin néogène de Vera apporte des données fort instructives pour l'interprétation du a phénomène Mio-Pliocène » en Méditerranée occidentale. a) Au point de vue biostratigraphique La coupe de Cuevas del Almanzora permet d'observer, pour la première fois en Méditerranée, une succession continue de foraminifères planctoniques du Messinien au Pliocène inférieur. Les biozones à G. acostaensis, G. humerosa-G. duterérei, G. mediterranea-G. conomiozea et G. margaritae se succèdent sans hiatus évolutif. b) Au point de vue géodynamique Le bassin de Vera montre une grande variété dans les modalités du passage Miocène-Pliocène, depuis des discordances à la périphérie du bassin jusqu'à une sédimentation vaseuse continue en son centre. L'étude des profils sismiques offshore montre de nombreux exemples comparables, en relation avec le comportement structural du substratum fragmenté en horst et graben mobiles. Des mouvements tectoniques distensifs ont eu lieu à la limite Miocène-Pliocène. Ils ont eu pour résultat un approfondissement relatif des bassins méditerranéens mais ceci ne représente qu'un épisode parmi d'autres d'un processus de distension inauguré au Miocène supérieur et qui s'est prolongé jusqu'au début du Quaternaire. II semble prudent en tous cas, de ne pas exagérer cet approfondissement de la mer au Pliocène. c) Au point de vue paléogéographique L'exemple du bassin de Vera prouve la pérennité des conditions marines durant le Messinien du moins dans certaines parties de la Méditerranée. Ceci implique naturellement des liaisons continues avec l'Atlantique, et exclut un dessèchement général du bassin méditerranéen durant les temps messiniens. La paléogéographie de la zone bétique durant le Miocène supérieur est caractérisée par une extrême compartimentation du domaine marin constitué de bassins subsidents, communiquant par des seuils. Cette compartimentation s'accentue durant le Messinien, favorisant la naissance de milieux confinés, propices à une sédimentation évaporitique subaquatique. Finalement, on insistera : sur la diversité de la paléogéographie messinienne en Méditerranée occidentale où existent ensemble, toujours sous contrôle tectonique, des sillons marins et des bassins marins évaporitiques à tendance euxinique, des lagunes évaporitiques, des régions à dépôts continentaux sans évaporites. <br> I) In the internai zone of the wastern Betic Ranges, the Neogene consists of two cuite different complexes - An early Neogene complex of Early ta Middle Miocene age, always much tectonized. Because of the dislocations and successive erosions it underwent, it is rather seldom preserved ; - A lote Neogene complex corresponding to the lote Miocene and the Pliocene is clearly exposed in several basins. Though it is rather strongly folded, its paleogeographic pattern remains clear. An important compressive orogenic phase thus occurred between the Serravalian and the Tortonian. It was followed by an extension phase that was no less important and, from Upper Miocene times onwards, announces a new period in the paleogeographic history of this part of fhe western Mediterranean area. 2) The Turre and Cuevas del Almanzora sections yield the most complete succession of the lote Neogene in the Vera Basin. In short, the stratigraphic sequence lying unconformably on the pre-Neogene or tectonized early Neogene substratum is as follows, from bottom to top - A conglomeratic phic rocks. continental complex, reddish in color, with blocks of metamor- The lateral presence of marine interbedding with G. acostaensis makes it possible to date it as Tortonian (Tortonian I with G. acostaensis without G. pseudomiocenica) ; - Angular unconformity; - Littoral conglomerates, turbidite marls and detrital contain a Tortonian microfauna (Tortonian II with G. miocenica) ; - Gray marls with turbidite interbedding. The planktonic foraminiferal assemblage of the G. humerosa-G. dutertrei zone which occurs at the base quickly becomes richer with the appearance of G. mediterranea and G. conomiozea, which define the base of the Messinian. The Cuevas del Almanzora section shows a continuous sedimentation going from Messinian to Pliocene marls. The latter are clearly characterized by the G. margaritae and G. puncticulata biozones
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