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Trans-Andean Geophysical Profile, Southern Colombia

1973; Geological Society of America; Volume: 84; Issue: 9 Linguagem: Inglês

10.1130/0016-7606(1973)84 2.0.co;2

1943-2674

James E. Case, JERRY BARNES, GABRIEL PARÍS Q., Humberto González I., ALVARO VIÑA,

Environmental and Ecological Studies

Research Article| September 01, 1973 Trans-Andean Geophysical Profile, Southern Colombia J. E. CASE; J. E. CASE 1U.S. Geological Survey, Corpus Christi, Texas 78411 Search for other works by this author on: GSW Google Scholar JERRY BARNES; JERRY BARNES 2Humble Oil and Refining Company, Midland, Texas 79701 Search for other works by this author on: GSW Google Scholar GABRIEL PARÍS Q.; GABRIEL PARÍS Q. 3INGEOMINAS, Carrera 9a, No. 5-62, Popayán, Colombia Search for other works by this author on: GSW Google Scholar HUMBERTO GONZÁLEZ I.; HUMBERTO GONZÁLEZ I. 4INGEOMINAS, Apartado Aéreo 4865, Bogotá, D.E., Colombia Search for other works by this author on: GSW Google Scholar ALVARO VIÑA ALVARO VIÑA 4INGEOMINAS, Apartado Aéreo 4865, Bogotá, D.E., Colombia Search for other works by this author on: GSW Google Scholar Author and Article Information J. E. CASE 1U.S. Geological Survey, Corpus Christi, Texas 78411 JERRY BARNES 2Humble Oil and Refining Company, Midland, Texas 79701 GABRIEL PARÍS Q. 3INGEOMINAS, Carrera 9a, No. 5-62, Popayán, Colombia HUMBERTO GONZÁLEZ I. 4INGEOMINAS, Apartado Aéreo 4865, Bogotá, D.E., Colombia ALVARO VIÑA 4INGEOMINAS, Apartado Aéreo 4865, Bogotá, D.E., Colombia Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1973) 84 (9): 2895–2904. https://doi.org/10.1130/0016-7606(1973)84 2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation J. E. CASE, JERRY BARNES, GABRIEL PARÍS Q., HUMBERTO GONZÁLEZ I., ALVARO VIÑA; Trans-Andean Geophysical Profile, Southern Colombia. GSA Bulletin 1973;; 84 (9): 2895–2904. doi: https://doi.org/10.1130/0016-7606(1973)84 2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Negative Bouguer anomalies (−80 mgals) near the Pacific coast of southern Colombia define the position of the Tertiary Bolívar trough. Values increase eastward to a huge positive anomaly (+75 mgals) over Mesozoic "eugeosynclinal" rocks of the western Andes. This anomaly is part of the West Colombian gravity high, which extends from Panamá into western Ecuador and is caused by shallow mafic crust. Bouguer anomalies are strongly negative (−220 mgals) over pre-Mesozoic(?) metamorphic rocks, Mesozoic(?) granitic bodies, and Tertiary to Holocene volcanic rocks of the central Andes between Pasto and Ipiales. The steep gravity gradient between the West Colombian gravity high and the negative anomaly of the central Andes represents the transition between mafic crust to the west and continental crust to the east. This zone parallels the Romeral-Cauca megashear system. East of the Andes, Bouguer anomalies range from −50 to −120 mgals over a Mesozoic-Tertiary basin of the Putumayo district, indicating that the crust there is thinner or denser than it is beneath the central Andes.Models derived from gravity data suggest that the crust is about 45 km thick under the south-central Colombian Andes. If this is correct, the crust must thicken southward along the strike of the Andes, as thicknesses of 70 km have been reported in the Andes of southern Perú, Bolivia, and northern Chile by Lomnitz (1962) and James (1971a). Such differing crustal thicknesses may reflect different intensities of tectonic activity, greater crustal thickness indicating more intense or rapid growth of the volcano-plutonic arc or foreshortening of an existing crustal section. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.