No. Registros Solicitud 1 5614 colombia
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DE - DESCRIPTORS: Andes-; Antilles-; Bolivia-; Caribbean-region; case-studies; Colombia-; data-acquisition; data-handling; data-processing; faults-; geophysical-methods; geophysical-profiles; geophysical-surveys; Latin-America; Lesser-Antilles; overthrust-faults; petroleum-; petroleum-exploration; seismic-methods; seismic-profiles; South-America; surveys-; Trinidad-; Trinidad-and-Tobago; vertical-seismic-profiles; West-Indies CC - CATEGORY CODES: 20-Applied-geophysics; 29A-Economic-geology,-geology-of-energy-sources DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic IL - ILLUSTRATION: sects. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States IS - ISSN: 1052-3812 AN - ACCESSION NUMBER: 1996-020652 UD - UPDATE CODE: 199608 Registro 4982 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: Posicion sistematica de un reptil marino con base en los restos fosiles encontrados en capas del Cretacico superior en Yaguara (Huila) Translated Title: Systematic position of a marine reptile based on other fossils encountered in the Upper Cretaceous beds in Yaguara, Huila. AU - AUTHORS: Paramo-Maria-Euridice AF - AUTHOR AFFILIATION: Apartado 250703, Santafe de Bogota, Colombia SO - SOURCE: Revista de la Academia Colombiana de Ciencias Exactas, Fisicas y Naturales. 19; 72, Pages 63-80. 1994. PB - PUBLISHER: Academia Colombiana de Ciencias Exactas, Fisicas y Naturales. Bogota, Colombia. 1994. CP - COUNTRY OF PUBLICATION: Colombia PY - PUBLICATION YEAR: 1994 LA - LANGUAGE: Spanish LS - LANGUAGE OF SUMMARY: English DE - DESCRIPTORS: bones-; Chordata-; Colombia-; Cretaceous-; Diapsida-; Huila-Colombia; Lacertilia-; Lepidosauria-; Magdalena-Valley; Mesozoic-; Mosasauridae-; new-taxa; Reptilia-; South-America; Squamata-; taxonomy-; Tetrapoda-; Turonian-; Upper-Cretaceous; Vertebrata-; Villeta-Formation; Yaguara-Colombia; Yaguarasaurus-columianus CC - CATEGORY CODES: 11-Vertebrate-paleontology DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 26; illus. incl. strat. cols., 3 plates, 2 tables, geol. sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IS - ISSN: 0370-3908 CO - CODEN: RCCFAO AN - ACCESSION NUMBER: 1996-024631 UD - UPDATE CODE: 199609 Registro 4983 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: Modelo de desplazamiento entre la Cordillera oriental de Colombia y los Andes de Merida Translated Title: Model of displacement between the Eastern Cordillera of Colombia and the Andes of Merida. AU - AUTHORS: Ujueta-L-Guillermo AF - AUTHOR AFFILIATION: Universidad Nacional, Departamento de Geociencias, Santafe de Bogota, Colombia SO - SOURCE: Revista de la Academia Colombiana de Ciencias Exactas, Fisicas y Naturales. 19; 72, Pages 95-105. 1994. PB - PUBLISHER: Academia Colombiana de Ciencias Exactas, Fisicas y Naturales. Bogota, Colombia. 1994. CP - COUNTRY OF PUBLICATION: Colombia PY - PUBLICATION YEAR: 1994 LA - LANGUAGE: Spanish LS - LANGUAGE OF SUMMARY: English DE - DESCRIPTORS: Andes-; Colombia-; displacements-; Eastern-Cordillera; faults-; landform-evolution; lateral-faults; left-lateral-faults; lineaments-; Merida-Venezuela; models-; orientation-; seismicity-; South-America; strike-slip-faults; tectonics-; Venezuela- CC - CATEGORY CODES: 16-Structural-geology DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 17; illus. incl. 1 plate, geol. sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IS - ISSN: 0370-3908 CO - CODEN: RCCFAO AN - ACCESSION NUMBER: 1996-024632 UD - UPDATE CODE: 199609 Registro 4984 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: A new look at the closure of the Isthmus of Panama and the initiation of the great American interchange. AU - AUTHORS: Campbell-K-E AF - AUTHOR AFFILIATION: Natural History Museum of Los Angeles County, Los Angeles, CA, United States BK - BOOK TITLE: In: Society of Vertebrate Paleontology, Fifty-fourth annual meeting; abstracts of papers. BA - BOOK AUTHORS: Padian-Kevin (chairperson) SO - SOURCE: Journal of Vertebrate Paleontology. 14; 3, Suppl., Pages 19. 1994. PB - PUBLISHER: University of Oklahoma. Norman, OK, United States. 1994. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1994 CN - CONFERENCE INFORMATION: Society of Vertebrate Paleontology, Fifty-fourth annual meeting. Seattle, WA, United States. Oct. 19-22, 1994. LA - LANGUAGE: English DE - DESCRIPTORS: biogeography-; Central-America; Chordata-; closure-; Colombia-; islands-; land-bridges; migration-; North-America; paleogeography-; Panama-; South-America; suture-zones; uplifts-; Vertebrata- CC - CATEGORY CODES: 12-Stratigraphy DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IS - ISSN: 0272-4634 AN - ACCESSION NUMBER: 1996-024794 UD - UPDATE CODE: 199609 Registro 4985 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: New material of the Cretaceous turtle Desmatochelys lowi. AU - AUTHORS: Irby-Grace-V; Elliott-David-K; Hutchison-J-Howard AF - AUTHOR AFFILIATION: Museum of Northern Arizona, Department of Geology, Flagstaff, AZ, United States BK - BOOK TITLE: In: Society of Vertebrate Paleontology, Fifty-fourth annual meeting; abstracts of papers. BA - BOOK AUTHORS: Padian-Kevin (chairperson) SO - SOURCE: Journal of Vertebrate Paleontology. 14; 3, Suppl., Pages 31. 1994. PB - PUBLISHER: University of Oklahoma. Norman, OK, United States. 1994. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1994 CN - CONFERENCE INFORMATION: Society of Vertebrate Paleontology, Fifty-fourth annual meeting. Seattle, WA, United States. Oct. 19-22, 1994. LA - LANGUAGE: English DE - DESCRIPTORS: Anapsida-; Arizona-; Black-Mesa; Cenomanian-; Chelonia-; Chordata-; Colombia-; Cretaceous-; cyclothems-; Desmatochelyidae-; Desmatochelys-; Desmatochelys-lowi; Greenhorn-Limestone; jaws-; Mancos-Shale; Mesozoic-; North-America; northern-Arizona; planar-bedding-structures; Reptilia-; sea-level-changes; sedimentary-structures; skulls-; South-America; Tetrapoda-; transgression-; Turonian-; United-States; Upper-Cretaceous; Vertebrata-; Western-Interior; Western-Interior-Seaway CC - CATEGORY CODES: 11-Vertebrate-paleontology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IS - ISSN: 0272-4634 AN - ACCESSION NUMBER: 1996-024869 UD - UPDATE CODE: 199609 Registro 4986 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: Mammalian paleontology, paleobotany and geochronology of the Miocene intermontain basins of southern Ecuador. AU - AUTHORS: Madden-R-H; Burnham-R; Swisher-C-C III; Carlini-A-A; Walton-A-H AF - AUTHOR AFFILIATION: Duke University Medical Center, Department of Biological Anthropology and Anatomy, Durham, NC, United States BK - BOOK TITLE: In: Society of Vertebrate Paleontology, Fifty-fourth annual meeting; abstracts of papers. BA - BOOK AUTHORS: Padian-Kevin (chairperson) SO - SOURCE: Journal of Vertebrate Paleontology. 14; 3, Suppl., Pages 35. 1994. PB - PUBLISHER: University of Oklahoma. Norman, OK, United States. 1994. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1994 CN - CONFERENCE INFORMATION: Society of Vertebrate Paleontology, Fifty-fourth annual meeting. Seattle, WA, United States. Oct. 19-22, 1994. LA - LANGUAGE: English DE - DESCRIPTORS: absolute-age; Andean-Orogeny; Ayancay-Group; Biblian-Formation; biostratigraphy-; C-14; carbon-; Catamayo-Basin; Cenozoic-; Chordata-; Cingulata-; Colombia-; Cuence-Basin; Ecuador-; faunal-list; Giron-Basin; isotopes-; La-Venta-Formation; Loma-Blanca-Formation; Mammalia-; Mangan-Formation; Miocene-; Nabon-Basin; Neogene-; Oligocene-; Paleogene-; Pisces-; Plantae-; preservation-; radioactive-isotopes; South-America; southern-Ecuador; Tertiary-; Tetrapoda-; Toxodontidae-; Vertebrata- CC - CATEGORY CODES: 08-General-paleontology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IS - ISSN: 0272-4634 AN - ACCESSION NUMBER: 1996-024895 UD - UPDATE CODE: 199609 Registro 4987 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: Northern South America. AU - AUTHORS: Donovan-Stephen-K AF - AUTHOR AFFILIATION: University of the West Indies, Department of Geology, Kingston, Jamaica BK - BOOK TITLE: In: Caribbean geology; an introduction. BA - BOOK AUTHORS: Donovan-Stephen-K (editor); Jackson-Trevor-A (editor) SO - SOURCE: Pages 229-247. 1994. PB - PUBLISHER: University of the West Indies Publisher's Association. Kingston, Jamaica. 1994. CP - COUNTRY OF PUBLICATION: Jamaica PY - PUBLICATION YEAR: 1994 LA - LANGUAGE: English DE - DESCRIPTORS: basins-; Caribbean-region; Cenozoic-; Colombia-; evolution-; Guyana-Shield; mountains-; physiographic-provinces; South-America; tectonics-; tectonostratigraphic-units; Venezuela- CC - CATEGORY CODES: 12-Stratigraphy; 16-Structural-geology DT - DOCUMENT TYPE: Book BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 89; illus. incl. geol. sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IB - ISBN: 976-41-0033-3 AN - ACCESSION NUMBER: 1996-025734 UD - UPDATE CODE: 199609 Registro 4988 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: Gas monitoring at active volcanoes. AU - AUTHORS: Stix-John; Heiligmann-Martin; Morrow-William-H; Hickson-Cathie AF - AUTHOR AFFILIATION: Universite de Montreal, Departement de Geologie, Montreal, PQ, Canada BK - BOOK TITLE: In: Geological Association of Canada; Mineralogical Association of Canada; annual meeting; program with abstracts--Association Geologique du Canada; Association Mineralogique du Canada; reunion annuelle; programme et resumes. BA - BOOK AUTHORS: Anonymous SO - SOURCE: Program with Abstracts - Geological Association of Canada; Mineralogical Association of Canada; Canadian Geophysical Union, Joint Annual Meeting. 19; Pages 107. 1994. PB - PUBLISHER: Geological Association of Canada. Waterloo, ON, Canada. 1994. CP - COUNTRY OF PUBLICATION: Canada PY - PUBLICATION YEAR: 1994 CN - CONFERENCE INFORMATION: Geological Association of Canada; Mineralogical Association of Canada; annual meeting--Association Geologique du Canada; Association Mineralogique du Canada; reunion annuelle. Waterloo, ON, Canada. May 16-18, 1994. LA - LANGUAGE: English DE - DESCRIPTORS: Andes-; carbon-dioxide; carbon-monoxide; Colombia-; degassing-; eruptions-; faults-; Galeras-; gases-; infrared-spectra; leaching-; monitoring-; noble-gases; patterns-; quantitative-analysis; radon-; remote-sensing; samplers-; sampling-; soil-gases; solubility-; South-America; spectra-; volcanoes-; volcanology- CC - CATEGORY CODES: 24-Quaternary-geology; 02A-General-geochemistry DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IS - ISSN: 0701-8738 CO - CODEN: PAACD6 AN - ACCESSION NUMBER: 1996-030139 UD - UPDATE CODE: 199610 Registro 4989 de 5614 - GeoRef Disc 4: 1993-1996 TI - TITLE: A suggested improvement to the mortar bar method of evaluation of the alkali-aggregate reaction. AU - AUTHORS: Mejia-Vallejo-Maria-del-Pilar; Hoyos-Patino-Fabian; Valencia-Julian-Vidal AF - AUTHOR AFFILIATION: Universidad Nacional, Medellin, Colombia BK - BOOK TITLE: In: Proceedings; Seventh international congress; International Association of Engineering Geology--Comptes-rendus; Septieme Congress International; Association Internationale de Geologie de l'Ingenieur. BA - BOOK AUTHORS: Oliveira-R (editor); Rodrigues-L-F (editor); Coelho-A-G (editor); Cunha-A-P (editor) SO - SOURCE: Congres International - Association International de Geologie de l'Ingenieur = International Congress - International Association of Engineering Geology. 7, Vol. V; Pages 3279-3283. 1994. PB - PUBLISHER: [publisher varies]. [location varies], International. 1994. RP - RESEARCH PROGRAM: IGC (International Geological Congress) CP - COUNTRY OF PUBLICATION: International PY - PUBLICATION YEAR: 1994 CN - CONFERENCE INFORMATION: Seventh international congress; International Association of Engineering Geology. Lisbon, Portugal. Sept. 5-9, 1994. LA - LANGUAGE: English LS - LANGUAGE OF SUMMARY: French DE - DESCRIPTORS: aggregate-; Colombia-; concrete-; construction-materials; evaluation-; mortar-bar-method; Pereira-Colombia; South-America; structures- CC - CATEGORY CODES: 30-Engineering-geology DT - DOCUMENT TYPE: Serial; Conference-Document BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 1; illus. incl. 4 tables. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. IB - ISBN: 90-5410-508-9 CO - CODEN: #01720 AN - ACCESSION NUMBER: 1996-042975 UD - UPDATE CODE: 199615 Registro 4990 de 5614 - GeoRef Disc 4: 1993-1996 BK - BOOK TITLE: Integrated approach to seismic event location; 2, Sources of location uncertainty for teleseismic and local network data. BA - BOOK AUTHORS: Frohlich-C CA - CORPORATE AUTHOR: University of Texas at Austin, Institute for Geophysics, Austin, TX, United States, performer NT - NOTES: Contract F19628-91-K-0026; Project 2309 PB - PUBLISHER: Pages: 58. 1994. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1994 LA - LANGUAGE: English AB - ABSTRACT: The locations of seismic events determined from travel times by independent agencies differ for at least three reasons, including differences in picking of or availability of the phases, effects produced by individual structural peculiarities of each station, and systematic mislocations caused by the choice of the travel time model used for relocation. The present study evaluates earthquake locations for events in thin geographically diverse regions chosen to represent a broad spectrum of location problems. These are: Macquarie Ridge; Bucaramanga, Colombia; and Efate, Vanuatu. The evaluation methods include a comparison of locations reported by different agencies, an analysis of the sources of the variance of travel-time residuals, and a determination of the volume of groups of events thought to originate from a common source region. For the data analyzed it appears that station-dependent effects are a more significant source of location differences than are effects related to picking phase arrivals or choice of velocity model. Also, this study finds many situations where it seems inappropriate to utilize the strategy of minimizing travel time variance to improve location quality. Seismic event location, Seismic strain, Seismic discrimination. DE - DESCRIPTORS: Bucaramanga-Colombia; Colombia-; discriminant-analysis; earthquakes-; epicenters-; focus-; instruments-; Macquarie-Ridge; Melanesia-; models-; Oceania-; seismic-networks; seismographs-; South-America; statistical-analysis; teleseismic-signals; traveltime-residuals; Vanuatu-; velocity- CC - CATEGORY CODES: 19-Seismology DT - DOCUMENT TYPE: Report BL - BIB LEVEL: Monograph NN - ANNOTATION: Final report, July 1, 1991-Feb. 28, 1994. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. Reference includes data from NTIS database, National Technical Information Service, Springfield, VA, United States AV - AVAILABILITY: National Technical Information Service, (703)605-6000, order number AD-A284 579/0NEG, Springfield, VA, United States AN - ACCESSION NUMBER: 1996-047296 UD - UPDATE CODE: 199616 Registro 4991 de 5614 - GeoRef Disc 4: 1993-1996 BK - BOOK TITLE: Seismic stratigraphy of the southern offshore Guajira Basin, Colombia. BA - BOOK AUTHORS: Hosie-Alfredo CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1994 DG - DEGREE GRANTED: Master's DI - DEGREE GRANTING INSTITUTION: University of Oklahoma. Norman, OK, United States. Pages: 141. 1994. LA - LANGUAGE: English AB - ABSTRACT: The Offshore Guajira Basin is an important hydrocarbon bearing province of northeastern Colombia. The geology of this area is complex and not well studied. Part of the complexity is due to the Cuiza wrench fault system, a fault system active since the Eocene. A seismic stratigraphic study of the Offshore Guajira Basin was conducted incorporating some 1,200 kilometers of reflection seismic dam. Thirteen defined sequences were evaluated using: A) Nine boreholes to constrain the lithology, fluids, and paleontological ages and environment of the sequences; B) Reflector configurations to define seismic facies; C) Characterization of the clastic wedges into the delta-type tendency; D) Seismic attributes to define the hydrocarbon indicators; and finally, E) Integrated data to describe the geohistory of the basin. The internal architecture of the basin is illustrated by structure maps, isochron maps, and cross sections between the boreholes. The geology of the study area has been profoundly influenced by the evolution of the Cuiza dextral wrench fault system. The north block of the Cuiza fault, the Cuiza Ridge, has continuously uplifted and tilted northward since the Middle Oligocene. On the western side of the Cuiza Ridge, the Dorado uplift was active from the Oligocene to the Late Middle Miocene, as evidenced by the lap-out of these sequences against the structure. Uplift of the East Cuiza Ridge occurred during the formation of the Late Middle Miocene unconformity that removed all the Miocene sequences from the top of structure. Between the Cuiza fault and the Chuchupa uplift, the narrow structural Cuiza Trough developed. South of the Trough, the Chuhupa uplift remained active until the Late Middle Miocene. Until this time only a thin portion of the Early Miocene sequence was deposited on top of the structure. The area south of the fault tilted to the west and experienced erosion during the Middle Middle Miocene. The environment from the Eocene to the Early Middle Miocene was littoral to inner sublittoral. During the Middle Miocene a period of rapid subsidence is inferred based on the predominantly thick sequences with a bathyal paleoenvironmental signature. During the Upper Miocene to the Holocene, the environments were predominantly outer to inner sublittoral. The continuous uplift of the northern block of the Cuiza Fault influenced the distribution of sediments by acting as a barrier for the coarse clastic sediments from the south. Three clastic wedges are defined using the seismic facies maps. The deltas are characterized as high energy wave dominated deltas that prograded westward. Three periods of carbonate deposition are identified which occurred during the Eocene, Early Middle Miocene and the Pliocene-Pleistocene. The seismic attributes are constrained on the Chuchupa gas field in order to determine possible hydrocarbon indicators (HDI's). A dim spot was recognized over the Early Miocene sand reservoir over the Chuchupa uplift. Additional potential (DH's were observed elsewhere. DE - DESCRIPTORS: basin-analysis; Cenozoic-; Chuchupa-Field; clastic-wedges; Colombia-; Cuiza-Fault; Eocene-; faults-; geophysical-methods; geophysical-surveys; Guajira-Basin; hydrocarbon-indicators; northeastern-Colombia; offshore-; Paleogene-; petroleum-; reflection-methods; sedimentation-; seismic-methods; seismic-stratigraphy; South-America; surveys-; Tertiary-; uplifts- CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources; 12-Stratigraphy; 20-Applied-geophysics DT - DOCUMENT TYPE: Thesis-or-Dissertation BL - BIB LEVEL: Monograph IL - ILLUSTRATION: Refs: 42; illus. incl. 10 tables. RF - REFERENCE SOURCE: GeoRef, Copyright 2000, American Geological Institute. AN - ACCESSION NUMBER: 1996-065550 UD - UPDATE CODE: 199620 Registro 4992 de 5614 - GeoRef Disc 4: 1993-1996 BK - BOOK TITLE: Structural and sedimentary evolution of the Irra Basin, northern Colombian Andes. BA - BOOK AUTHORS: Sierra-Gloria-Maria CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1994 DG - DEGREE GRANTED: Master's DI - DEGREE GRANTING INSTITUTION: SUNY at Binghamton. Binghamton, NY, United States. Pages: 102. 1994. LA - LANGUAGE: English AB - ABSTRACT: The Irra basin in central Colombia is one of a number of sedimentary basins that developed since middle Tertiary and have been controlled by the N-S Cauca and Romeral fault systems. Studies were carried out to investigate the stratigraphy, sedimentary facies and source area of the sediments and structures of this basin and to relate them to its tectonic evolution. The initial sediments filling the basin correlated with the Oligocene-Miocene Amaga Formation, unconformably lie on Pre-Tertiary basic volcanic and metamorphic rocks and consist of sandstones, conglomerates and shales with some thin coal beds. In Late Miocene time, andesitic-dacitic magmas intruded the Amaga Formation; these intrusions remain today as massive and resistant bodies cropping out in the surrounding less resistant sedimentary units. From the Late Miocene to Pleistocene, a sequence of fluvial, epiclastic and pyroclastic deposits, subdivided in this work as units A, B, and C jointly define the Irra Formation, and were deposited unconformably over the older sedimentary rocks. Unit C is dominated by a compositionally uniform sequence of polymict conglomerates intercalated with sub-lithoarenites and small amounts of feldsphatic lithoarenites that together represent alluvial fan deposits; unit B is characterized by monolithic conglomerates containing andesitic fragments set in a plagioclase, hornblende, bypiramidal quartz-rich matrix interbedded with tuffs and lapillistones representing debris flows, hyperconcentrated flood-flows and pyroclastic flows; Unit A consists of tuffs, lapillistone, and conglomerates interpreted to be the result of air-falls and debris flows. Unit B and C are in part laterally correlative, but locally unit B is younger than unit C. Unit A is younger than both units B and C and lies unconformably and disconformably on them. Evidence from the Irra basin indicates that: 1- Sedimentary rocks of the Irra Formation are associated with both uplifting and volcanic activity in the Central Cordillera to the east: 2- the Romeral fault system has had at least two senses of slip since late Miocene to Pleistocene; right lateral movement initially allowed the Irra basin to form as a pull-apart basin, and left-lateral slip later compressed the sedimentary rocks producing folding and thrusting. Paleomagnetic studies suggest that the left lateral slip component of the Romeral system was smaller than the earlier right-lateral component as the net effect produced a rotation of about 15 degrees clockwise. Anisotropy of magnetic susceptibility (AMS) reveals that the rock fabrics are tectonically controlled, being closely related to foliation plot; these secondary magnetic fabrics, although not visible in outcrop or hand men, clearly overprint and obscure the expected primary flow fabrics. Yüklə 20,82 Mb. Dostları ilə paylaş:
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