ALBERT

Description: Between 08.08.2003 and 02.09.2003, bathymetric data was acquired offshore Guatemala and Costa Rica during the R/V SONNE cruise SO173/2. The expedition comprised geophysical and biological research objectives. One aim was the acquisition of geophysical data for a better understanding of recent and long-term evolution of the Middle America Landbridge and mass flux into the subduction system. Moreover, the cruise was also dedicated to studying the sensory systems of mesopelagic fish, cephalopods, crustaceans and teleosts by using trawl gear and morphometric studies. Bathymetric mapping with the multibeam echosounder (MBES) SIMRAD EM120 was utilized to obtain a full coverage bathymetric map along the El Salvador and Guatemalan continental slope and to complete previous maps by filling gaps along the continental slope and oceanic plate of Nicaragua. Further geophysical instruments, such as the sub-bottom profiler PARASOUND, magnetometer, a dredge and seismic instrumentation, and biological equipment including trawling gear and lab instrumentation, complemented the research equipment. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Description of the data source: During the SO173/2 cruise, the hull-mounted multibeam echosounder (MBES) SIMRAD EM120 was utilized to perform bathymetric mapping. It allows to conduct surveys in water depths of up to 11,000 m. Two transducer arrays transmit successive frequency coded acoustic signals (11.25 to 12.6 kHz). Data acquisition is based on successive emission-reception cycles of the signal. While the emission beam has a dimension of 150° across and 2° along track, the reception is obtained from 191 overlapping beams with widths of 2° across and 20° along track. The beam footprint has a dimension of 2° by 2°. The beam spacing can be set to equidistant or equiangular. For further information on the system, consult: https://www.km.kongsberg.com/ Depth is estimated from each beam by using the two-way travel time and the beam angle known from each beam, and taking into account the ray bending due to refraction in the water column by sound speed variations. Combining phase and amplitude is used to provide measurement accuracy practically independent of the beam pointing angle. During the SO173 cruise, the EM120 was used continuously. At the beginning of the cruise, a sound velocity profile was measured to a depth of 2000 m. Responsible person during this cruise / PI: Wilhelm Weinrebe (wweinrebe@ifm-geomar.de) Chief Scientist: Wilhelm Weinrebe (wweinrebe@ifm-geomar.de) CR: http://oceanrep.geomar.de/13407/1/Geomar-Report-116.pdf CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2003/20040060.htm This dataset was published as part of: Geersen, Jacob (2019): Collated bathymetric data from convergent margins that experienced tsunami earthquakes. PANGAEA, https://doi.org/10.1594/PANGAEA.899049

Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 16 (2015): 4261–4274, doi:10.1002/2015GC006100.

Description: We present results of marine MT acquisition in the Alboran sea that also incorporates previously acquired land MT from southern Spain into our analysis. The marine data show complex MT response functions with strong distortion due to seafloor topography and the coastline, but inclusion of high resolution topography and bathymetry and a seismically defined sediment unit into a 3-D inversion model has allowed us to image the structure in the underlying mantle. The resulting resistivity model is broadly consistent with a geodynamic scenario that includes subduction of an eastward trending plate beneath Gibraltar, which plunges nearly vertically beneath the Alboran. Our model contains three primary features of interest: a resistive body beneath the central Alboran, which extends to a depth of ∼150 km. At this depth, the mantle resistivity decreases to values of ∼100 Ohm-m, slightly higher than those seen in typical asthenosphere at the same depth. This transition suggests a change in slab properties with depth, perhaps reflecting a change in the nature of the seafloor subducted in the past. Two conductive features in our model suggest the presence of fluids released by the subducting slab or a small amount of partial melt in the upper mantle (or both). Of these, the one in the center of the Alboran basin, in the uppermost-mantle (20–30 km depth) beneath Neogene volcanics and west of the termination of the Nekkor Fault, is consistent with geochemical models, which infer highly thinned lithosphere and shallow melting in order to explain the petrology of seafloor volcanics.

Description: NSF Grant Number: EAR080-9074; Spanish National Projects Grant Number: CTM2009-07039-E/MAR, CTM2011-30400-C02-02

Description: 2016-06-19

Description: © The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Tectonophysics 689 (2016): 25-39, doi:10.1016/j.tecto.2016.03.009.

Description: The Palomares continental margin is located in the southeastern part of Spain. The margin main structure was formed during Miocene times, and it is currently part of the wide deformation zone characterizing the region between the Iberian and African plates, where no well-defined plate boundary occurs. The convergence between these two plates is here accommodated by several structures, including the left lateral strike-slip Palomares Fault. The region is characterized by sparse, low to moderate magnitude (Mw 〈 5.2) shallow instrumental earthquakes, although large historical events have also occurred. To understand the recent tectonic history of the margin we analyze new high-resolution multibeam bathymetry data and re-processed three multichannel seismic reflection profiles crossing the main structures. The analysis of seafloor morphology and associated subsurface structure provides new insights of the active tectonic features of the area. In contrast to other segments of the southeastern Iberian margin, the Palomares margin contains numerous large and comparatively closely spaced canyons with heads that reach near the coast. The margin relief is also characterized by the presence of three prominent igneous submarine ridges that include the Aguilas, Abubacer and Maimonides highs. Erosive processes evidenced by a number of scars, slope failures, gullies and canyon incisions shape the present-day relief of the Palomares margin. Seismic images reveal the deep structure distinguishing between Miocene structures related to the formation of the margin and currently active features, some of which may reactivate inherited structures. The structure of the margin started with an extensional phase accompanied by volcanic accretion during the Serravallian, followed by a compressional pulse that started during the Latemost Tortonian. Nowadays, tectonic activity offshore is subdued and limited to few, minor faults, in comparison with the activity recorded onshore. The deep Algero-Balearic Basin is affected by surficial processes, associated to halokinesis of Messinian evaporites.

Description: The authors acknowledge the support from the Spanish Ministry of Economy and Competitiveness through the Complementary Action ESF TopoEurope TOPOMED (CGL2008-03474-E/BTE), National Projects SHAKE (CGL2011-30005-C02-02) and INSIGHT (CTM2015-70155-R), and the EU-COST Action FLOWS (ES 1301).

Description: 2017-03-18