How does the continental crust thin in a hyper-extended rifted margin; insights from the Iberia margin

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http://abstractsearch.agu.org/meetings/2011/FM/T21A-2297.html
Author(s): Sutra, E.; Manatschal, G.
Author Affiliation(s): Primary:
Institut de Physique du Globe de Strasbourg, EOST, Strasbourg, France
Volume Title: AGU 2011 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2011; American Geophysical Union 2011 fall meeting, San Francisco, CA, Dec. 5-9, 2011. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: During the last twenty years the knowledge of rifted margins was strongly challenged by new observations in particular related to ODP drilling and seismic refraction surveys. The discovery of hyper-thinned continental crust and exhumed mantle in deep water rifted margins results in two fundamental questions: How does the crust thin and what controls extreme crustal thinning and mantle exhumation? Reflection and refraction seismic lines indicate that distinct domains in rifted margins are separated by structures that cut decoupling levels in the crust and eventually transfer deformation to mantle levels. This evolution from decoupled to coupled deformation on a crustal level may explain the crustal architecture of magma-poor rifted margins. A comparison of seismic sections across the Iberia rifted margin shows that decoupled extension was distributed in the North and more localized in the South. In contrast coupled extension resulted in similar structures and width of the extended domain along the whole margin. Based on drill hole data the transition from decoupled to coupled deformation occurred during the Tithonian (±145 Ma). A delay or retardation of subsidence observed over the hyper-extended coupled domain may indicate that crustal thinning had to occur simultaneously with lithospheric necking and may be controlled by deeper mantle processes. Based on our observations we suggest that the decoupled deformation affecting the crust seems to be mainly controlled by crustal structure and rheology, both of which are dependent on inheritance. In contrast the coupled deformation cuts the entire crust and occurs in a completely embrittled crust and is therefore much less dependent on the initial structure of the margin.
Year of Publication: 2011
Research Program: ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Continental crust; Continental margin; Coupling; Crust; Crustal thinning; Decoupling; Deformation; Europe; Exhumation; Geophysical methods; Iberian Peninsula; Jurassic; Lithosphere; Mantle; Mesozoic; Ocean Drilling Program; Plate tectonics; Refraction methods; Rheology; Rifting; Seismic methods; Southern Europe; Tithonian; Upper Jurassic
Record ID: 2015077198
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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