georefid:2008-039739SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=10.1144/SP282.32007-01-01publicationgeorefid:2008-039739doi:10.1144/SP282.3Hopper, J. R.Texas A&M University, Department of Geology and Geophysics, College Station, TX, United StatesauthorFunck, T.Universite Louis Pasteur, FranceauthorTucholke, B. E.Universidade de Aveiro, PortugalauthorGeological Society of London, London, United KingdompublisherdocumentHardcopyIn: Karner, G. D. (editor), Manatschal, G. (editor), Pinheiro, L. M. (editor), Imaging, mapping and modelling continental lithosphere extension and breakup28247-61Seismic reflection and refraction data from the Flemish Cap margin off Newfoundland reveal the large-scale structure of a magma-starved rifted margin. There is little evidence for significant extensional deformation of the Flemish Cap, consistent with the hypothesis that it behaved as a microplate throughout the Mesozoic. The seismic data highlight important asymmetries at a variety of scales that developed during the final stages of continental breakup and the onset of oceanic sea-floor spreading. In strong contrast to the conjugate Galicia Bank margin, Flemish Cap shows: (1) an abrupt necking profile in continental crust, thinning from 30 km thick to 3 km thick over a distance of 80 km, and a narrow, less than 20 km-wide, zone of extremely thin continental crust; (2) no clear evidence for horizontal detachment structures beneath continental crust similar to the "S" reflection; and (3) evidence for at least a 60 km-wide zone of anomalously thin oceanic crust that began accreting to the margin shortly after continental crustal separation. The oceanic crust averages only 3-4 km thick and in places is as thin as 1.3 km thick, although seismic layer 3 is missing where this occurs. The data suggest that there are large spatial and temporal variations in the available melt supply following continental breakup as oceanic sea-floor spreading becomes established. In addition, wide-angle data show that anomalously slow mantle P-wave velocities appear approximately where continental crust has thinned to 6-8 km thick, indicating that low-degree serpentinization begins where the entire crust has become embrittled.completedSolid-earth geophysicsApplied geophysicsAtlantic OceanbasaltsbasementCanadacontinental margincrustcrustal thinningEastern CanadaFlemish CapGalicia Bankgeophysical methodsgeophysical profilesgeophysical surveysigneous rocksLeg 103magnetic anomaliesmantlemappingmetasomatismmid-ocean ridge basaltsNewfoundlandNewfoundland and LabradorNorth AtlanticNortheast AtlanticNorthwest AtlanticOcean Drilling ProgramODP Site 639plate tectonicsriftingSCREECHsea-floor spreadingseismic methodsseismic profilesserpentinizationsurveysunconformitiesvelocity structurevolcanic rocksurn:org.iodp:exp:103urnlargerWorkCitationcampaignurn:org.iodp:exp:103:site:639urnlargerWorkCitationstudyurn:org.iodp:exp:103urnlargerWorkCitationcampaignEnglishgeoscientificInformation-50.0000-40.000040.000048.0000