Seismic stratigraphy and tectonic history of the Iberia abyssal plain

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doi: 10.2973/odp.proc.sr.149.245.1996
Author(s): Wilson, R. C. L.; Sawyer, Dale S.; Whitmarsh, Robert B.; Zerong, J.; Carbonell, J.
Author Affiliation(s): Primary:
Open University, Department of Earth Sciences, Milton Keynes, United Kingdom
Other:
Rice University, United States
Ocean Drilling Program, United States
Université Pierre et Marie Curie, France
Dalhousie University, Canada
Universidad de Granada, Spain
Université de Nantes, France
Florida State University, United States
Universidade de Aveiro, Portugal
INTERGEOS, Netherlands
University of Waterloo, Canada
Lamont-Doherty Earth Observatory, United States
University of Tokyo, Japan
GEOMAR, Federal Republic of Germany
University of Leicester, United Kingdom
University of Texas at El Paso, United States
University of Michigan, United States
Universität Kiel, Federal Republic of Germany
Cornell University, United States
California State University, United States
Iowa State University, United States
University of Maryland System, United States
Open University, United Kingdom
University of California, United States
Institute of Oceanographic Sciences, United Kingdom
Institute of Earth Sciences, Spain
Volume Title: Proceedings of the Ocean Drilling Program; scientific results, Iberia abyssal plain; covering Leg 149 of the cruises of the Drilling Vessel JOIDES Resolution; Balboa Harbor, Panama, to Lisbon, Portugal; sites 897-901, 10 March-25 May 1993
Volume Author(s): Whitmarsh, Robert B.; Sawyer, Dale S.; Klaus, Adam; Beslier, Marie-Odile; Collins, Eric S.; Comas, María Carmen; Cornen, Guy; de Kaenel, Eric; Pinheiro, Luis de Menezes; Gervais, Elisabeth; Gibson, Ian L.; Harry, Dennis L.; Hobart, Michael A.; Kanamatsu, Toshiya; Krawcyzk, Charlotte M.; Liu, Li; Lofts, Jeremy C.; Marsaglia, Kathleen M.; Meyers, Philip A.; Milkert, Doris; Milliken, Kitty L.; Morgan, Julia K.; Ramirez, Pedro; Seifert, Karl E.; Shaw, Timothy J.; Wilson, Chris; Yin, Chuan; Zhao, Xixi
Source: Proceedings of the Ocean Drilling Program; scientific results, Iberia abyssal plain; covering Leg 149 of the cruises of the Drilling Vessel JOIDES Resolution; Balboa Harbor, Panama, to Lisbon, Portugal; sites 897-901, 10 March-25 May 1993, Robert B. Whitmarsh, Dale S. Sawyer, Adam Klaus, Marie-Odile Beslier, Eric S. Collins, María Carmen Comas, Guy Cornen, Eric de Kaenel, Luis de Menezes Pinheiro, Elisabeth Gervais, Ian L. Gibson, Dennis L. Harry, Michael A. Hobart, Toshiya Kanamatsu, Charlotte M. Krawcyzk, Li Liu, Jeremy C. Lofts, Kathleen M. Marsaglia, Philip A. Meyers, Doris Milkert, Kitty L. Milliken, Julia K. Morgan, Pedro Ramirez, Karl E. Seifert, Timothy J. Shaw, Chris Wilson, Chuan Yin and Xixi Zhao. Proceedings of the Ocean Drilling Program, Scientific Results, Vol.149, p.617-633. Publisher: Texas A&M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 0884-5891
Note: In English. 30 refs.; illus., incl. sketch maps, sects., 1 table, strat. cols.
Summary: This paper presents an interpretation of seismic reflection profiles acquired in the southeastern part of the Iberia Abyssal Plain using lithostratigraphic and biostratigraphic information obtained from ODP Leg 149 and DSDP Site 398. Six seismic units are recognized; Units 1 to 5 span the lower Albian to Holocene, but some doubt exists concerning the age of Unit 6; it is probably Valanginian to Aptian in age. Only seismic Units 1 and 2 are not deformed significantly by a previously identified Neogene compressional episode. Unit 2 onlaps the folds, and Unit 1 truncates them in places and oversteps Unit 2 toward the fold crests. The boundary between Units 2 and 3 coincides with the late/middle Miocene boundary and so constrains the main compressional event to a very short period of time. Undulatory and inclined reflections in Units 1-3 indicate significant sediment transport by contour currents since the middle Eocene. Depressions between acoustic basement highs were filled by sediments equivalent to Units 4-6, commencing in the Early Cretaceous (probably during the Valanginian). The sedimentary fill shows simple onlapping relationships with the flanks of basement highs, most of which were completely sediment covered by Eocene time. Applying accepted criteria for the recognition of synrift packages on seismic sections, we found no unequivocal examples of synrift intervals in the study area or on previously published seismic sections from the deep Galicia Margin. Therefore, we conclude that the rift episode affecting the western Iberian Margin, from the Iberia Abyssal Plain northward, occurred over a very short interval, and/or that depositional rates were very low, so that synrift sedimentary sequences did not accumulate to produce a seismically resolvable thickness. The results of this study strongly suggest that rifting on the southeastern margin of the Iberia Abyssal Plain occurred at the latest before the Hauterivian, probably early in the Valanginian and after the Tithonian. We suggest that the synrift episode beneath the deep Galicia Margin postdates Tithonian-Berriasian shallow-water carbonates and predates Valanginian siliciclastic sediments that infill the basement topography created during rifting. Unfortunately, almost no in situ sediments were obtained from Leg 149 sites that would have enabled paleodepth estimates to be made for the Cretaceous. Therefore, it was not possible to quantify tectonically driven postrift subsidence. However, using digitized versions of the interpreted seismic lines, smoothed total tectonic subsidence (TTS) plots along these lines were produced, from which crustal thickness and extension factors (β) were determined. TTS of up to 6 km is consistent with the subsidence of either normal oceanic crust formed ≥100 Ma or continental crust thinned by β of between 5 and 7 at 135 Ma).
Year of Publication: 1996
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; 16 Structural Geology; 20 Geophysics, Applied; Albian; Atlantic Ocean; Biostratigraphy; Cenozoic; Correlation; Cretaceous; DSDP Site 398; Deep Sea Drilling Project; Europe; Geophysical methods; Geophysical surveys; IPOD; Iberian Peninsula; Iberian abyssal plain; Leg 149; Leg 47; Lithofacies; Lithostratigraphy; Lower Cretaceous; Mesozoic; Miocene; Neogene; North Atlantic; Northeast Atlantic; Ocean Drilling Program; Reflection methods; Seismic migration; Seismic stratigraphy; Southern Europe; Subsidence; Surveys; Tectonics; Tectonostratigraphic units; Tertiary
Coordinates: N403000 N410000 W0113000 W0123000
N405736 N405736 W0104306 W0104306
Record ID: 2007088120
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