HEAT-FLOW DENSITY ACROSS THE CENTRAL ANDEAN SUBDUCTION ZONE

Citation
M. Springer et A. Forster, HEAT-FLOW DENSITY ACROSS THE CENTRAL ANDEAN SUBDUCTION ZONE, Tectonophysics, 291(1-4), 1998, pp. 123-139
Citations number
70
Categorie Soggetti
Geochemitry & Geophysics
Journal title
ISSN journal
00401951
Volume
291
Issue
1-4
Year of publication
1998
Pages
123 - 139
Database
ISI
SICI code
0040-1951(1998)291:1-4<123:HDATCA>2.0.ZU;2-V
Abstract
New and revised heat-flow density determinations for the Central Andes in Chile and Bolivia between 60 degrees and 75 degrees W and between 15 degrees and 30 degrees S are presented. Heat flow was determined fr om temperature logs obtained from fourteen boreholes in northern Chile and from a large Bottom-Hole Temperature (BHT) data set in Bolivia. T hermal data were corrected for perturbations resulting from drilling, topography, and fluid circulation, and effects of porosity and tempera ture were considered in adjusting thermal conductivity for in-situ con ditions. Thus, the 74 reliable heat-how values available were used to interpret heat flow in the context of lithospheric conditions. The hea t flow in the Andean orogen shows a strong dependence on the different tectono-morphologic units. Clusters of heat-how values projected onto a W-E profile reflect significant changes from the Nazca Plate in the west to the Chaco Basin in the east. Heat-flow density is low (20 mW/ m(2)) in the area of the Coastal Cordillera and high (50-180 mW/m(2)) in the active magmatic are and the Altiplano. The back-are region is c haracterized by a comparably high heat how (80 mW/m(2)) whereas the An dean foreland has a heat flow of 40 mW/m(2), which is slightly lower t han the heat how in the adjacent Brazilian Shield farther east. The Ce ntral Andean subduction zone shows a heat-flow pattern similar to the active margin of the North American continent, but differs in the subd uction parameters. Consequently, this results in different lithospheri c thermal conditions. (C) 1998 Elsevier Science B.V. All rights reserv ed.