American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 730334 bytes)    Cited by

TECTONICS, VOL. 22, NO. 2, 1010, doi:10.1029/2002TC001410, 2003

Décollement depth versus accretionary prism dimension in the Apennines and the Barbados

Sabina Bigi

Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza,” Rome, Italy


Federica Lenci

Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza,” Rome, Italy


Carlo Doglioni

Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza,” Rome, Italy


J. Casey Moore

Earth Sciences Department, University of California, Santa Cruz, California, USA


Eugenio Carminati

Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza,” Rome, Italy


Davide Scrocca

Istituto di Geologia Ambientale e Geoingegneria, Consiglio Nazionale delle Ricerche (CNR), Rome, Italy


Abstract

Along representative cross sections of the Apennines and the Northern Barbados accretionary prisms, we measured the area, the décollement depth, the angle α of the upper envelope and the angle β of the dip of the regional monocline. The continental sections of the Apennines accretionary prism have a deeper décollement than the oceanic sections of the Northern Barbados, 6–10 km depth and <1 km depth, respectively, because the sediment pile is thinner on the incoming Barbados plate and its denser oceanic structure is more easily subducted. Considering the frontal 50 km, the Apennines have an average cross-sectional area of 500 km2 and the Northern Barbados Ridge of 100 km2. The total area is a function of the depth of the décollement plane. Therefore, at a given amount of subduction, the deeper the décollement depth is, the bigger the area of the wedge will result, assuming negligible compaction and erosion. As a consequence, the larger area/volume and higher elevation of the Apennines with respect to the Barbados is determined by the Apenninic deeper décollement. Despite these differences, the geometry of both décollements is, in some cases, comparable, in particular, close to the boundary between the crystalline crust and the sediment pile, where the main density and strength contrasts are concentrated. Variations in depth of the décollement occur moving along strike in both accretionary prisms. The geometry of the prisms is further controlled by the different values of α and β, their sum, and the distance of the accretionary prism relative to the subduction hinge.

Published 10 April 2003.

Index Terms: 8099 Structural Geology: General or miscellaneous; 8150 Tectonophysics: Plate boundary—general (3040); 8122 Tectonophysics: Dynamics, gravity and tectonics.

Read Full Article (file size: 730334 bytes)    Cited by

Citation: Bigi, S., F. Lenci, C. Doglioni, J. C. Moore, E. Carminati, and D. Scrocca (2003), Décollement depth versus accretionary prism dimension in the Apennines and the Barbados, Tectonics, 22(2), 1010, doi:10.1029/2002TC001410.