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

Read Full Article (file size: 1200802 bytes)    Cited by

TECTONICS, VOL. 22, NO. 3, 1023, doi:10.1029/2002TC001386, 2003

Tectonic erosion of the Peruvian forearc, Lima Basin, by subduction and Nazca Ridge collision

Peter D. Clift

Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA


Ingo Pecher

Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand


Nina Kukowski

GeoForschungsZentrum Potsdam, Potsdam, Germany


Andrea Hampel

GeoForschungsZentrum Potsdam, Potsdam, Germany


Abstract

Subsidence of Lima Basin, part of the Peruvian forearc, is controlled by tectonic erosion by the subducting Nazca plate. Multichannel seismic reflection data coupled with age and paleowater depth constraints derived from Ocean Drilling Program (ODP) coring now allow the rates of erosion to be reconstructed through time. In trenchward locations the forearc has experienced limited recent relative uplift (700–850 m) likely due to preferential basal erosion under the center of Lima Basin. Long-term subsidence driven by basal tectonic erosion dominates and is fastest closest to the trench. Since 47 Ma (Eocene) up to 148 km of the plate margin have been lost at an average rate of up to 3.1 km myr−1. Appoximately 110 km of that total appears to be lost since 11 Ma, implying much faster average rates of trench retreat (10 km myr−1) since collision of the Nazca Ridge with the Lima Basin at 11 Ma. Although there is no clear subsidence event at ODP Site 679 during the time at which Nazca Ridge was subducting beneath this part of the forearc (4–11 Ma), the more trenchward ODP Sites 682 and 688 show significant deepening after 11 Ma indicating that subduction of the ridge accelerates tectonic erosion. Long-term rates of crustal erosion in the region of Lima Basin are greater than estimates of regional arc magmatic productivity, implying that such margins are net sinks of continental crust.

Received 18 March 2002; accepted 27 February 2003; published 4 June 2003.

Index Terms: 3025 Marine Geology and Geophysics: Marine seismics (0935); 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 8015 Structural Geology: Local crustal structure; 0935 Exploration Geophysics: Seismic methods (3025).

Read Full Article (file size: 1200802 bytes)    Cited by

Citation: Clift, P. D., I. Pecher, N. Kukowski, and A. Hampel (2003), Tectonic erosion of the Peruvian forearc, Lima Basin, by subduction and Nazca Ridge collision, Tectonics, 22(3), 1023, doi:10.1029/2002TC001386.