No. Registros Solicitud 1 5614 colombia

AB - ABSTRACT: A very prolific association of foraminifera, represented by 17 different species between benthonic and planktonic forms, has been identified by a detailed analysis of the Umir Formation (La Julia Creek Section, Middle Magdalena Valley). The presence of Ammobaculites colombianus Cushman and Hedberg with Rugoglobigerina macrocephala Bronnimann in the lower part of the sedimentary sequence, Umir Formation, is reported for the first time. This finding allows to assign a Maastrichtian age to this unit (at least to the lower part) instead of Campanian-Maastrichtian as it had been previously attempted. Lack of foraminifera with stratigraphical value in the upper part of the sedimentary sequence did not allow to identify the presence of the latest Maastrichtian and the lower most Paleocene record in the Umir Formation. Both a morphological description and a taxonomical and stratigraphical discussion are given for each of the reported species.

DE - DESCRIPTORS: Ammobaculites-; authigenic-minerals; benthonic-taxa; biostratigraphy-; Campanian-; Cenozoic-; Colombia-; Cretaceous-; description-; Foraminifera-; Invertebrata-; La-Julia-Creek; lithostratigraphy-; Lituolacea-; Maestrichtian-; Magdalena-Valley; Mesozoic-; microfossils-; Paleocene-; paleoenvironment-; Paleogene-; Protista-; Senonian-; South-America; taxonomy-; Tertiary-; Textulariina-; Umir-Formation; Upper-Cretaceous

CC - CATEGORY CODES: 10-Invertebrate-paleontology; 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 58; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027051

UD - UPDATE CODE: 200309

Registro 445 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Comentarios acerca de la evolucion geologica del Alto Catatumbo

Translated Title: Comments on the geologic evolution of the upper Catatumbo River basin.

AU - AUTHORS: Galvis-Vergara-Jaime; Rodriguez-Sierra-Gloria

AF - AUTHOR AFFILIATION: Carrera 16 A-31, Santafe de Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 95-107. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: This paper presents a brief analysis of the magmatism in the upper basin of the Catatumbo river, with special reference to a magmatic event whose deposits have characteristics which suggest that it took place during the Cenozoic. A resume of the tectonics of the upper Catatumbo basin, and its relations and geological similarities with the Bucaramanga region are also included.

DE - DESCRIPTORS: Algodonal-River-basin; Andes-; Bucaramanga-Colombia; Catatumbo-River-basin; Cenozoic-; Eastern-Cordillera; erosion-features; gneisses-; igneous-rocks; intrusions-; landform-evolution; lava-; magmatism-; metamorphic-rocks; Northern-Andes; pillow-lava; pyroclastics-; South-America; tectonics-; Tejo-River-basin; volcanic-rocks

CC - CATEGORY CODES: 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N080000; N083000; LONG: W0724500; W0731500.

IL - ILLUSTRATION: Refs: 4; illus. incl. geol. sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027050

UD - UPDATE CODE: 200309

Registro 446 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Edad y origen del "complejo metasedimentario Aranzazu-Manizales" en los alrededores de Manizales (Departamento de Caldas, Colombia)

Translated Title: Age and origin of the metasedimentary Aranzazu-Manizales Complex near Manizales, Caldas Department, Colombia.

AU - AUTHORS: Gomez-Cruz-Arley-de-J; Moreno-Sanchez-Mario; Pardo-Trujillo-Andres

AF - AUTHOR AFFILIATION: Universidad de Caldas, Facultad de Geologia, Manizales, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 83-93. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: On the western flank of the Central Cordillera (Colombia), near Manizales, Lozano et al. (1975) named the Mesozoic rocks as the "Complejo Metasedimentario Aranzazu-Manizales". Detailed studies of this unit allow us to determinate two metasedimentary sequences with typical characteristics. The first crops out to the east of Manizales (Caldas); it is composed by siliciclastic rocks with continental components (quartzites and schists) and abundant deformed fossils of Brachiopods (?), Gastropods, Pelecypods and Cephalopods, of which the genus Oxytropidoceras sp. (det. Etayo-Serna) allows us to assign a partial mid-Albian age. The facial characteristics suggest deposition on a continental margin, influenced by currents in submarine canyons or submarine fans with a continental source of sediments. The second sequence crops out to the west in faulted contacts, characterized by plutonic and oceanic affinity volcanic rock fragments. This facies may have been the result of sedimentation on a submarine fan influenced by volcanic activity and turbidity currents near high scarps. In this work, this unit is correlated with the Quebradagrande Formation (sensu Botero 1963).

DE - DESCRIPTORS: Abejorral-Formation; Andes-; biostratigraphy-; Caldas-Colombia; Central-Cordillera; Colombia-; correlation-; intrusions-; lithostratigraphy-; Manizales-Colombia; Mesozoic-; metamorphic-rocks; metasedimentary-rocks; Northern-Andes; paleoenvironment-; quartzites-; Quebradagrande-Formation; schists-; siliciclastics-; South-America

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N050000; N053000; LONG: W0751500; W0754500.

IL - ILLUSTRATION: Refs: 14; illus. incl. strat. cols., geol. sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027049

UD - UPDATE CODE: 200309

Registro 447 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Sobre la edad de la secuencia metasedimentaria que encaja las mineralizaciones auriferas vetiformes en la region del Taraira (Vaupes)

Translated Title: Age of the metasedimentary host rock sequence of auriferous vein mineralization in the Taraira region, Vaupes.

AU - AUTHORS: Carrillo-Victor-M

AF - AUTHOR AFFILIATION: Departamento MINERALCO, Santafe de Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 73-83. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: The metasedimentary sequence hosting the lode gold mineralizations in the Taraira (Vaupes) region, has been correlated or compared with stratigraphic units o sequences from other countries with ages ranging from from 2.600 to 2.000 My. Recent works carried out by MINERALCO S.A., suggest the possibility that the age of this sequence be more recent than the previously considered age: Precambrian, less than 1.200 My.

DE - DESCRIPTORS: absolute-age; Amazonas-Colombia; Colombia-; dates-; gold-ores; host-rocks; La-Pedrera-Formation; lithostratigraphy-; metal-ores; metamorphic-rocks; metasedimentary-rocks; mineral-deposits,-genesis; mineralization-; Piraparana-Formation; Precambrian-; Roraima-Formation; Sierra-de-Machado; South-America; Taraira-Colombia; Vaupes-Colombia; veins-

CC - CATEGORY CODES: 27A-Economic-geology,-geology-of-ore-deposits; 03-Geochronology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: S010000; N023000; LONG: W0720000; W0743000.

IL - ILLUSTRATION: Refs: 12; illus. incl. strat. cols., sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027048

UD - UPDATE CODE: 200309

Registro 448 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Estructuras anulares en la Cordillera Oriental de Colombia y su relacion a fenomenos diapiricos

Translated Title: Anular structures in the Eastern Cordillera of Colombia and their relation with diapirism phenomena.

AU - AUTHORS: Galvis-Jaime; Cortes-Ricardo; de-la-Espriella-Ricardo

AF - AUTHOR AFFILIATION: Carrera 16 A-31, 3er. Piso, Santafe de Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 59-72. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: There is a wide area, in the Cordillera Oriental of Colombia, which presents very special geographic and geologic characteristics. In the same zone there are some very well defined types of mineralization, which do not appear in the rest of the country. The tectonics of the zone presents not well explained particularities. The zone extends from Villarrica (Tolima) (southern part) to Mesa de Los Santos and Sierra del Cocuy piedmont (north); and from the Borde Llanero fault to the east, to Bituima and Salina faults to the west.

DE - DESCRIPTORS: Andes-; Aptian-; Borde-Llanero-Fault; chemically-precipitated-rocks; chlorides-; Colombia-; correlation-; Cretaceous-; diapirism-; Eastern-Cordillera; evaporites-; Fomeque-Member; gneisses-; granites-; gypsum-; halides-; halite-; igneous-rocks; lead-ores; lithostratigraphy-; Lower-Cretaceous; Magdalena-Valley; Mesozoic-; metal-ores; metamorphic-rocks; mineral-deposits,-genesis; mineralization-; Northern-Andes; plutonic-rocks; Precambrian-; salt-domes; sedimentary-rocks; Sierra-del-Cocuy; South-America; structural-controls; sulfates-; sulfur-; sulfur-deposits; Tolima-Colombia; Villeta-Formation; zinc-ores

CC - CATEGORY CODES: 26A-Economic-geology,-general,-deposits

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 12; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027047

UD - UPDATE CODE: 200309

Registro 449 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Contribucion al conocimiento de la estratigrafia de las rocas sedimentarias de Monte Frio (Jurasico Inferior, Valle Superior del Magdalena-Colombia)

Translated Title: Stratigraphy of sedimentary rocks of Monte Frio, Lower Jurassic, upper Magdalena Valley, Colombia.

AU - AUTHORS: Rodriguez-P-Miguel-Angel; Garcia-Gabriel-Rodriguez; Viana-R-Ricardo-Leon

AF - AUTHOR AFFILIATION: INGEOMINAS, Regional Alto Magdalena, COL, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 45-57. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: The "Rocas Sedimentarias de Monte Frio" represent the record of a marine sedimentological event with high subaerial volcanic influence in the Upper Magdalena Valley. Recent detailed studies of this unit, which crops out at the Monte Frio area, close to the town of Natagaima (Tolima), have allowed to determine the lithological conformation, the thickness and the relations with the adjacent units; these characteristics are described in this paper. The sequence of the "Rocas Sedimentarias de Monte Frio", 423,5 m thick, is subdivided into 6 segments to detail its conformation; in general, the succession consists of intercalations of micritic limestones, very fine grained sandstones, siltstones, mudstones, chert, tuffs and occasionally intraformational conglomerates; the predominant color of the rocks is black and dark gray. The lower contact is covered in the area, and the upper part is concordant and transitional with the volcanic red beds of the Saldana Formation. The depositional environment was variable from shallow marine to subaerial with a high volcanic and tectonic influence which caused instability in the depositional basin. The presence of Liassic ostracodes and conchostraca in the "Rocas Sedimentarias de Monte Frio" locates its stratigraphy over the Payande Formation and the Chicala Member; although it is not discarded that in this sequence can be included some parts of both of these units. It is recommended to consider the Chicala Member and the "Rocas Sedimentarias de Monte Frio" within the Payande Formation to make easier the differentiation from the Saldana Formation.

DE - DESCRIPTORS: carbonate-rocks; Chicala-Member; Colombia-; Jurassic-; limestone-; lithostratigraphy-; Lower-Jurassic; Magdalena-Valley; Mesozoic-; micrite-; Natagaima-Colombia; paleoenvironment-; Payande-Formation; Saldana-Formation; sedimentary-rocks; South-America; Tolima-Colombia

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 16; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027046

UD - UPDATE CODE: 200309

Registro 450 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Los pliegues de la Barrera de Guataqui-Girardot; Producto de un despegue de la cobertera Cretacica de la Cordillera Oriental?

Translated Title: Folds of the Guataqui-Girardot Barrier; a product of a Cretaceous detachment in the Eastern Cordillera?.

AU - AUTHORS: Kammer-Andreas; Mojica-Jairo

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Santa Fe de Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 33-43. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: In this paper the folds of the so-called barrier of Guataqui-Girardot are interpreted as detachment folds. In a first step, depths of a decollement horizon are calculated, using the classical excess-area method. These results are discussed in the light of a deformational scenario, which includes 1) uplift of the internal parts of the Eastern Cordillera and 2) a gravity-driven gliding of the Cretaceous cover toward its bordering depressions, giving rise to a partial tectonic denudation. It is concluded that, with respect to this scenario and in order to carry out a satisfactory retro-deformation by balanced areas, distributed shear and internal deformation should be allowed for as further parameters in the decollement calculations.

DE - DESCRIPTORS: Andes-; basement-; Colombia-; Cretaceous-; decollement-; deformation-; detachment-faults; Eastern-Cordillera; faults-; flexure-folds; folds-; geometry-; Guataqui-Barrier; Hilo-Formation; Jerusalen-Syncline; Limba-Anticline; Magdalena-Valley; Mesozoic-; Olini-Group; shear-; South-America; synclines-; tectonics-

CC - CATEGORY CODES: 16-Structural-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N043000; N050000; LONG: W0750000; W0753000.

IL - ILLUSTRATION: Refs: 17; illus. incl. sects., geol. sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027045

UD - UPDATE CODE: 200309

Registro 451 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Fotointerpretacion y observaciones de campo del flujo de escombros de Noviembre 13 de 1985 en Armero (Tolima, Colombia)

Translated Title: Photointerpretation and field observations of the debris flows of November 13, 1985 in Armero; Tolima, Colombia.

AU - AUTHORS: Ujueta-Guillermo; Mojica-Jairo

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Santafe de Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 19; Pages 5-20. 1995.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1995.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1995

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: The photointerpretation, using aerial photographs recorded from the Armero's Debris Flow, few days after it took place, are in agreement with survivors' reports, indicate that the event occurred in three principal pulses, each one with different hydrodynamic characteristics, as has been observed in other places of the world. In the first place there was a preceding muddy flow that only affected the shallower places such as the closer ones to the Lagunilla River; the first pulse was an extremely dense flow supersatured with solids with a variable and relatively low velocity that resulted in a continuous debris sheet that covered the flat lands with a thickness of up to 3 meters height and a radius of 2.5 km. The push and advance of this flow which included the biggest blocks was the responsible of the destruction of Armero. The effect of this flow was differential, as in higher zones the debris flow did not demolish houses and was injected though doors and windows. The high density of this flow was one of the main reasons that it did not affect some streets with high slopes. The second pulse consisted of high velocity turbulent running water, loaded with pebbles and gravels, which generated a high erosion capacity that stripped off the former fan, providing a terrace aspect and producing new distributary water channels. The third pulse was a low level water flow with a high concentration of gravel, sand and mud, which took place for several hours. It was concluded, from the photointerpretation, that the Armero's Debris Flow according to its hydrodynamic characteristics, reached the flatter topography and overflowed the Lagunilla's riverbed at different places.

DE - DESCRIPTORS: Andes-; Armero-Colombia; Central-Cordillera; Colombia-; damage-; debris-flows; erosion-features; eruptions-; floods-; fluvial-environment; geologic-hazards; geologic-maps; hydrodynamics-; interpretation-; Lagunilla-River; maps-; mass-movements; meltwater-; Nevado-del-Ruiz; Northern-Andes; photogeology-; preferential-flow; remote-sensing; South-America; terraces-; Tolima-Colombia; urban-environment; volcanoes-

CC - CATEGORY CODES: 22-Environmental-geology; 23-Geomorphology

DT - DOCUMENT TYPE: Serial; Map

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N045300; N050000; LONG: W0750000; W0753000.

MS - MAP SCALE: 1:75,000

MP - MAP TYPE: geologic-maps

IL - ILLUSTRATION: Refs: 9; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027044

UD - UPDATE CODE: 200309

Registro 452 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Sismotectonica de Colombia; deformacion continental activa y subduccion

Translated Title: Seismotectonics of Colombia; active continental deformation and subduction.

AU - AUTHORS: Taboada-A; Dimate-C; Fuenzalida-A

AF - AUTHOR AFFILIATION: Univ. Los Andes, Bogota, Colombia

SO - SOURCE: Fisica de la Tierra. 10; Pages 111-147. 1998.

PB - PUBLISHER: Editorial de la Universidad Complutense. Madrid, Spain. 1998.

CP - COUNTRY OF PUBLICATION: Spain

PY - PUBLICATION YEAR: 1998

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

DE - DESCRIPTORS: active-faults; active-margins; Andes-; Caribbean-Plate; Caribbean-region; catalogs-; Colombia-; earthquakes-; faults-; gravity-platforms; inversion-tectonics; marine-installations; Nazca-Plate; plate-convergence; plate-tectonics; seismicity-; seismotectonics-; South-America; subduction-zones; tectonics-

CC - CATEGORY CODES: 19-Seismology; 18-Solid-earth-geophysics

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 49; block diags., 1 table, geol. sketch maps.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from Instituto Geologico y Minero de Espana, Madrid, Spain

IS - ISSN: 0214-4557

AN - ACCESSION NUMBER: 2003-026113

UD - UPDATE CODE: 200309

Registro 453 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Geochronology and geochemistry of Grenvillian igneous suites in the northern Oaxacan Complex, southern Mexico; tectonic implications.

AU - AUTHORS: Keppie-J-Duncan; Dostal-J; Cameron-K-L; Solari-L-A; Ortega-Gutierrez-F; Lopez-R

AF - AUTHOR AFFILIATION: Saint Mary's University, Department of Geology, Halifax, NS, Canada

SO - SOURCE: Precambrian Research. 120; 3-4, Pages 365-389. 2003.

PB - PUBLISHER: Elsevier. Amsterdam, International. 2003.

CP - COUNTRY OF PUBLICATION: International

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: Chemical and U-Pb isotopic analyses of metaigneous rocks in the northern Oaxacan Complex in southern Mexico indicate that they form part of two granitic-gabbroic suites intruded at approximately 1157-1130 and approximately 1012 Ma, which were metamorphosed under granulite facies conditions between approximately 1004 and 980 Ma. Although the older suite has both within-plate and arc geochemical signatures, the arc characteristics (enrichment of La and Ce relative to Nb, Ta, and Th) are inferred to result from crustal contamination, a conclusion consistent with their negative epsilon (sub Nd) signatures. The younger suite is spatially associated with anorthosites (from which we were unable to acquire a protolith age), suggesting that collectively it forms part of anorthosite-mangerite-charnockite-granite (AMCG) suites. The tholeiitic nature of the mafic rocks along with the within-plate character of the felsic rocks suggests that they were intruded during extension related to either farfield backarc rifting, rifting above a slab window, or anorogenic intercontinental rifting. Potentially correlative AMCG suites are widespread in Mexico, the Grenville Province of eastern Canada and northeastern USA, and the Andean massifs of Colombia, however, Pb isotopic data most closely resemble those in South America. These data are consistent with published hypotheses that suggest Oaxaquia represents an exotic terrane derived from Amazonia.

DE - DESCRIPTORS: absolute-age; Brazil-; Brazilian-Shield; chemical-composition; chemical-ratios; correlation-; dates-; facies-; gabbros-; geochemistry-; granites-; granulite-facies; Grenvillian-Orogeny; igneous-rocks; major-elements; metamorphic-rocks; Mexico-; mineral-composition; nesosilicates-; Oaxacan-Complex; orthosilicates-; plate-tectonics; plutonic-rocks; Precambrian-; Proterozoic-; silicates-; South-America; trace-elements; U-Pb; upper-Precambrian; X-ray-fluorescence; zircon-