HR: 0800h
AN: T41A-09    [Abstracts]
TI: Crustal thickness estimates of Northwestern South America and their relation to the presence of batholithic bodies of economy interest
AU: * Hernandez, O
EM: ohernandezp@unal.edu.co
AF: Universidad Nacional de Colombia, Geosciences Department, Ed. Manuel Ancizar, Of 313, Ciudad Universitaria, Bogota, D.C 06, Colombia
AU: von Frese, R R
EM: vonfrese@osu.edu
AF: The Ohio State University, School of Earth Sciences, 125 South Oval Mall, 375 Mendenhall Lab., Columbus, OH 43210, United States
AU: Potts, L M
EM: lpotts@njit.edu
AF: New Jersey Institute of Technology, University heights, Newark, NJ 07102, United States
AB: A new model for the crustal evolution of northwestern South America (−8 S to 23.5 N, −90 W to −58.5 W) was developed from gravity derived MOHO depth estimates and tectonic features interpreted from correlative geopotential anomalies and seismic data. Crustal thickness estimates provide important constraints on the distribution of volcanic and seismic hazards, and mineral and energy deposits. Crustal thickness estimates were obtained by inversion of the compensated terrain gravity effects (CTGE) and compared against theoretical Airy MOHO and compiled seismic MOHO estimates. The thickness of the continental crust varies from 35 km to 55 km and shows that the mountain ranges are partially compensated by continental roots. The volumetric proportions of erupted rock types and geochemical characteristics likely are strongly correlated with the thickness and chemical characteristics of the crust through which the rising magmas travel. Crustal thicknesses from 45 to 55 km at the continent are related to the presence of andesitic batholiths of economic interest. Major deposits of base and precious metals of the Andean Mountains are related to intermediate to felsic intrusions. Porphyry copper-molybdenum deposits coincide with Mesozoic - Cenozoic orogenic belts and calc- alkaline volcanism. Major batholiths in the Central Andes, are related to gravity-inferred crustal thicknesses between 55 km to 60 km. Therefore, these results suggest that exploration of mineral deposits associated with batholithic intrusions in the Andes Mountains can be extended to crustal thicknesses from 45 km to 60 km.
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 5109 Magnetic and electrical properties (0925)
DE: 7205 Continental crust (1219)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8000 STRUCTURAL GEOLOGY
SC: Tectonophysics [T]
MN: 2007 Joint Assembly