The role of detachment faulting in the formation of an ocean-continent transition: insights from the Iberia Abyssal Plain

Manatschal, G., Froitzheim, N., Rubenach, M., and Turrin, B.D. (2001) The role of detachment faulting in the formation of an ocean-continent transition: insights from the Iberia Abyssal Plain. Geological Society Special Publication, 187. pp. 405-428.

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The Iberia Abyssal Plain segment of the West Iberia margin was drilled during Ocean Drilling Program Legs 149 and 173 and has been extensively studied geophysically. We present new microstructural investigations and new age data. These, together with observed distribution of upper- and lower-crustal and mantle rocks along the ocean-continent transition suggest the existence of three detachment faults, one of which was previously unrecognized. This information, together with a simple kinematic inversion of the reinterpreted seismic section Lusigal 12, allows discussion of the kinematic evolution of detachment faulting in terms of the temporal sequence of faulting, offset along individual faults, and thinning of the crust during faulting. Our study shows that the detachment structures recognized in the seismic profile became active only during a final stage of rifting when the crust was already considerably thinned to c. 12 km. The total amount of extension accommodated by the detachment faults is of the order of 32.6 km corresponding to a ß factor of about two. During rifting, the mode of deformation changed oceanwards. Initial listric faulting led to asymmetric basins, accommodating low amounts of extension, and was followed by a situation in which the footwall was pulled out from underneath a relatively stable hanging wall accommodating high amounts of extension. Deformation along the latter faults resulted in a conveyor-belt type sediment accumulation in which the exhumed footwall rocks were exposed, eroded and redeposited along the same active fault system.

Item ID: 13219
Item Type: Article (Research - C1)
ISSN: 0305-8719
Date Deposited: 24 Dec 2010 00:02
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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