Constraining the timing and geographical extent of accretion of oceanic crust in Ecuador; a combined 40Ar/39Ar and fission-track approach.

• Autores: R.A. Spikings, D. Seward, W. Winkler, R. Handler
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 4, 2002 (Ejemplar dedicado a: INTERNATIONAL WORKSHOP ON FISSION TRACK ANALISIS: THEORY AND APPLICATIONS), págs. 147-150
• Idioma: inglés
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• Resumen

  • White mica and biotite 40Ar/39Ar and zircon and apatite fission-track data from several traverses across the Eastern Cordillera and Amotape Complex of Ecuador in the northern Andes record distinct along-strike differences in the timing of post-Campanian accelerated crustal cooling. These data record rapid cooling rates of up to - 30- 20°C/My during - 70 - 55 Ma and - 43 - 30 Ma along the entire contemporaneous continental margin of Ecuador, which coincide with the accretion of the oceanic Pallatanga and Macuchi terranes respectively onto NWSouth America. Both ofthese geological provinces originated at the southern parts o f the leading and trailing boundaries of the Caribbean Plateau and accreted onto the margin during the approximately northeastward migration of the Plateau. Higher topography and elevated cooling rates of- 50°C/My at - 15 Ma and since - 9 Ma are restricted to the region north of l °30 'S within the Eastern Cordillera, which is situated above the postulated subductedflat-slab section of the aseismic Carnegie Ridge. Plate convergence rate calculations suggest the Carnegie Ridge collided with the Ecuador Trench at - 15 Ma, which caused the pre-existing coastal provinces to displace to the northeast, subsequently driving compression and uplift in northern Ecuador.