Benedict Preu
University of Bremen
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Featured researches published by Benedict Preu.
Geology | 2014
F.J. Hernández-Molina; Estefanía Llave; Benedict Preu; Gemma Ercilla; A. Fontan; Miguel Bruno; Nuno Serra; J.J. Gomiz; Rachel Brackenridge; Francisco Javier Sierro; Dorrik A. V. Stow; M. García; C. Juan; N. Sandoval; A. Arnáiz
We characterize the eastern Gulf of Cadiz, proximal to the Strait of Gibraltar, using a multidisciplinary approach that combines oceanographic, morphosedimentary, and stratigraphic studies. Two terraces (upper and lower) were identified along the middle slope. They are composed of several associated morphologic elements, including two large erosive channels, which allow us to determine a new and more detailed understanding of the Mediterranean Outflow Water (MOW) pathway and its deceleration upon exiting the Strait of Gibraltar. There is evidence for along-slope circulation and additional secondary circulation oblique to the main flow. The present upper core of the MOW flows along the upper terrace and the lower core flows along the lower terrace. However, the lower terrace shows larger and better defined erosive features on the seafloor than does the upper terrace; we attribute this to a denser, deeper, and faster MOW circulation that prevailed during past cold climates. Development of the present features started ca. 3.8–3.9 Ma, but the present morphology was not established until the late Pliocene–early Quaternary (3.2 to older than 2.0 Ma), when the MOW was enhanced, coeval with global cooling, a sea-level fall, and an increase in thermohaline circulation. We propose a direct link between the MOW and the Atlantic Meridional Overturning Circulation and therefore between the MOW and both the Northern Hemisphere and global climate. Our results have enabled a better understanding of a major overflow related to an oceanic gateway, and are of broad interest to geologists, climatologists, oceanographers, and petroleum geologists.
Geo-marine Letters | 2015
Lara F. Pérez; F. Javier Hernández-Molina; Federico Damián Esteban; Alejandro Tassone; Alberto R. Piola; Andrés Maldonado; Benedict Preu; Roberto A. Violante; Emanuele Lodolo
The aim of the present study was to characterise the morpho-sedimentary features and main stratigraphic stacking pattern off the Tierra del Fuego continental margin, the north-western sector of the Scotia Sea abyssal plain (Yaghan Basin) and the Malvinas/Falkland depression, based on single- and multi-channel seismic profiles. Distinct contourite features were identified within the sedimentary record from the Middle Miocene onwards. Each major drift developed in a water depth range coincident with a particular water mass, contourite terraces on top of some of these drifts being associated with interfaces between water masses. Two major palaeoceanographic changes were identified. One took place in the Middle Miocene with the onset of Antarctic Intermediate Water flow and the enhancement of Circumpolar Deep Water (CDW) flow, coevally with the onset of Weddell Sea Deep Water flow in the Scotia Sea. Another palaeoceanographic change occurred on the abyssal plain of the Yaghan Basin in the Late Miocene as a consequence of the onset of Southeast Pacific Deep Water flow and its complex interaction with the lower branch of the CDW. Interestingly, these two periods of change in bottom currents are coincident with regional tectonic episodes, as well as climate and Antarctic ice sheet oscillations. The results convincingly demonstrate that the identification of contourite features on the present-day seafloor and within the sedimentary record is the key for decoding the circulation of water masses in the past. Nevertheless, further detailed studies, especially the recovery of drill cores, are necessary to establish a more robust chronology of the evolutionary stages at the transition between the western Scotia Sea and the southern South Atlantic Ocean.
Geo-marine Letters | 2014
Fei Ai; Michael Strasser; Benedict Preu; Till J J Hanebuth; Sebastian Krastel; Achim J Kopf
Submarine landslides are common along the Uruguayan and Argentinean continental margin, but size, type and frequency of events differ significantly between distinct settings. Previous studies have proposed sedimentary and oceanographic processes as factors controlling slope instability, but also episodic earthquakes have been postulated as possible triggers. However, quantitative geotechnical slope stability evaluations for this region and, for that matter, elsewhere in the South Atlantic realm are lacking. This study quantitatively assesses continental slope stability for various scenarios including overpressure and earthquake activity, based on sedimentological and geotechnical analyses on three up to 36 m long cores collected on the Uruguayan slope, characterized by muddy contourite deposits and a locus of landslides (up to 2 km3), and in a canyon-dominated area on the northern Argentinean slope characterized by sandy contourite deposits. The results of shear and consolidation tests reveal that these distinct lithologies govern different stability conditions and failure modes. The slope sectors are stable under present-day conditions (factor of safety >5), implying that additional triggers would be required to initiate failure. In the canyon area, current-induced oversteepening of weaker sandy contourite deposits would account for frequent, small-scale slope instabilities. By contrast, static vs. seismic slope stability calculations reveal that a peak ground acceleration of at least 2 m/s2 would be required to cause failure of mechanically stronger muddy contourite deposits. This implies that, also along the western South Atlantic passive margin, submarine landslides on open gentle slopes require episodic large earthquakes as ultimate trigger, as previously postulated for other, northern hemisphere passive margins.
Krastel, S., Lehr, J., Winkelmann, D., Schwenk, T., Preu, B., Strasser, M., Wynn, R. B., Georgiopoulou, A. and Hanebuth, T. J. J. (2014) Mass Wasting Along Atlantic Continental Margins: A Comparison Between NW-Africa and the de la Plata River Region (Northern Argentina and Uruguay) Submarine Mass Movements and Their Consequences. Advances in Natural and Technological Hazards Research (37). Springer International Publishing, Cham, pp. 459-469. ISBN 978-3-319-00971-1 DOI 10.1007/978-3-319-00972-8_41 <http://dx.doi.org/10.1007/978-3-319-00972-8_41>. | 2014
Sebastian Krastel; J Lehr; Daniel Winkelmann; Tilmann Schwenk; Benedict Preu; Michael Strasser; Russell B. Wynn; Aggeliki Georgiopoulou; Till J J Hanebuth
The passive continental margins of the Atlantic Ocean are characterized by thick sedimentary successions, which might become unstable resulting in landslides of various sizes. The type of mass-wasting differs between individual margin sections but the reasons for these differences are not well understood. The NW-African continental margin is characterized by several large-scale but infrequent landslides, while the continental margin in the de la Plata River region (northern Argentina and Uruguay) shows widespread small-scale mass transport deposits. These different styles of mass wasting can be explained by different oceanographic and sedimentary settings. The margin off Northwest Africa is characterized by high primary productivity caused by oceanic upwelling as well as locally focused aeolian input resulting in relatively high sedimentation rates. This setting leads to sediment instabilities arising primarily from underconsolidation of deposited sediments and widespread weak layers. In contrast, the modern ocean margin off Uruguay and northern Argentina is characterized by strong contour currents and a high amount of fluvial sediment resulting in widespread contouritic deposits. These contourites are potentially unstable leading to smaller but more frequent landslides.
Deep Sea Research Part I: Oceanographic Research Papers, 75 . pp. 157-174. | 2013
Benedict Preu; F. Javier Hernández-Molina; Roberto A. Violante; Alberto R. Piola; C. Marcelo Paterlini; Tilmann Schwenk; Ines Voigt; Sebastian Krastel; V. Spiess
Geo-marine Letters | 2011
Sebastian Krastel; Gerold Wefer; Till J J Hanebuth; Andrew A. Antobreh; Tim Freudenthal; Benedict Preu; Tilmann Schwenk; Michael Strasser; Roberto Violante; Daniel Winkelmann
Marine Geology | 2012
Benedict Preu; Tilmann Schwenk; F. Javier Hernández-Molina; Roberto A. Violante; M. Paterlini; Sebastian Krastel; Juan Tomasini; Volkhard Spieß
Marine Geology | 2013
Ines Voigt; Ruediger Henrich; Benedict Preu; Alberto R. Piola; Till J J Hanebuth; Tilmann Schwenk; Cristiano Mazur Chiessi
Geo-marine Letters | 2011
Benedict Preu; Volkhard Spieß; Tilmann Schwenk; Ralph R. Schneider
Marine Geology | 2016
F. Javier Hernández-Molina; Matías Soto; Alberto R. Piola; Juan Tomasini; Benedict Preu; Phil Thompson; Gianluca Badalini; Adam Creaser; Roberto A. Violante; Ethel Morales; M. Paterlini; Héctor de Santa Ana