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Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies

Hernandez, Orlando
http://rave.ohiolink.edu/etdc/view?acc_num=osu1158512351

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Geological Sciences.
Northwestern South America is one of the most populated regions of the Americas with more than 80 million people concentrated along the Andes Mountains. This region includes a complex mosaic of tectonic plates that have produced devastating earthquakes, tsunamis, volcanic eruptions and landslides in the last decades. The region's economic development has also seriously suffered because the region is poorly explored for natural resources. To more effectively assess the tectonic hazards and mineral and energy resources of this region, we must improve our understanding of the tectonic setting that produced them. This research develops tectonic models for northwestern South America from satellite, airborne and surface gravity and magnetic data integrated with global digital topography, seismic, and GPS plate velocity data. Reliable crustal thickness estimates were obtained by inverse modeling of the magnetic anomalies and terrain compensated gravity anomalies. Correlated positive Terrain Gravity Effects (TGE) and Free Air Gravity Anomalies (FAGA) suggest that the crust-mantle interface under the northwestern Andes is closer to the surface than expected, indicating that these mountains are not isostatically compensated. Correlated negative FAGA anomalies observed along western South America and the Greater and Lesser Antilles islands are associated with isostatically disturbed mantle displaced by subducting oceanic plates. Subtracting TGE from the terrain-correlated FAGA (TCFAGA) yield compensated terrain gravity effect (CTGE) anomalies that characterize the Andes Mountains with deep roots of low density crust displacing denser underlying mantle and thickening the local crust. FAGA and TGE correlate at all levels of compensation, but the correlations are especially strong where the compensation is less than 100%. Correlated first vertical derivative FAGA (FVD(FAGA)) and differentially reduced-to-pole total field (DRTP) magnetic anomalies show crustal thickness variations and states of magneto-isostatic compensation. Continental crustal thickness estimates for the region are in the range from roughly 34 km to 55 km, conforming well to regional seismic constraints. Inversely correlated FVD(FAGA) and DRTP magnetic anomalies suggest thickness variations in the lower crust and thermal effects in terms of the Curie isotherm. Directly correlated FVD(FAGA) and DRTP magnetic anomalies indicate thickness variations of the upper crust due to the formation of recent topography.
Ralph von Frese (Advisor)
198 p.
Geology; Geophysics
Northwestern Andes; Isostasy; Gravity; Magnetics; Tectonics; South America; Seismicity

Recommended Citations

Citations

  • Hernandez, O. (2006). Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1158512351

    APA Style (7th edition)

  • Hernandez, Orlando. Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1158512351.

    MLA Style (8th edition)

  • Hernandez, Orlando. "Tectonic analysis of northwestern South America from integrated satellite, airborne and surface potential field anomalies." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1158512351

    Chicago Manual of Style (17th edition)

osu1158512351
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© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.