No. Registros Solicitud 1 5614 colombia
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CC - CATEGORY CODES: 02C-Geochemistry-of-rocks,-soils,-and-sediments; 05A-Igneous-and-metamorphic-petrology DT - DOCUMENT TYPE: Book; Conference-Document BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 11 RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique, Vandoeuvre-les-Nancy, France AN - ACCESSION NUMBER: 2003-035494 UD - UPDATE CODE: 200312 Registro 378 de 5614 - GeoRef : 2002-2004/12 TI - TITLE: A deterministic geometric representation of temporal rainfall; sensitivity analysis for a storm in Boston. AU - AUTHORS: Obregon-N; Sivakumar-B; Puente-C-E AF - AUTHOR AFFILIATION: Universidad Javeriana, Department of Civil Engineering, Bogota, Colombia SO - SOURCE: Journal of Hydrology. 269; 3-4, Pages 224-235. 2002. PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 2002. CP - COUNTRY OF PUBLICATION: Netherlands PY - PUBLICATION YEAR: 2002 LA - LANGUAGE: English AB - ABSTRACT: In an earlier study, Puente and Obregon [Water Resour. Res. 32 (1996) 2825] reported on the usage of a deterministic fractal-multifractal (FM) methodology to faithfully describe an 8.3 h high-resolution rainfall time series in Boston, gathered every 15 s and made of 1990 points, as the derived distribution of a classical multifractal measure via a fractal interpolating function. This work further studies the robustness of the FM methodology via an exhaustive sensitivity analysis aimed at obtaining even better FM descriptions for the Boston storm. This is carried out by varying a host of pertinent attributes that include usage of: (a) alternative objective functions for the inverse problem based on cumulative distributions of the records and of their derivatives; (b) a genetic algorithm in order to find the best FM parameters; (c) fractal interpolating functions passing by 3, 4 and 5 points, considering all relevant parameter-combination cases separately; and (d) two scales of aggregation, i.e. records with 199 and 1990 bins. The analysis indicates that previous results may indeed be improved when cumulative distributions of the records, rather than the records themselves, are employed in the FM parameter search, especially for representations based on 4 and 5 interpolating points and at the highest data resolution. DE - DESCRIPTORS: Boston-Massachusetts; chaos-; data-processing; digital-simulation; fractals-; geometry-; hydrology-; interpolation-; Massachusetts-; models-; multifractals-; numerical-models; rainfall-; sensitivity-analysis; storms-; Suffolk-County-Massachusetts; temporal-distribution; United-States CC - CATEGORY CODES: 21-Hydrogeology DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic MC - MAP COORDINATES: LAT: N422000; N422000; LONG: W0710500; W0710500. IL - ILLUSTRATION: Refs: 19; illus. incl. 1 table. RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands IS - ISSN: 0022-1694 CO - CODEN: JHYDA7 AN - ACCESSION NUMBER: 2003-035274 UD - UPDATE CODE: 200311 Registro 379 de 5614 - GeoRef : 2002-2004/12 TI - TITLE: The 19 January 1995 Tauramena (Colombia) earthquake; geometry and stress regime. AU - AUTHORS: Dimate-Cristina; Rivera-Luis; Taboada-Alfredo; Delouis-Bertrand; Osorio-Alonso; Jimenez-Eduardo; Fuenzalida-Andres; Cisternas-Armando; Gomez-Isabel AF - AUTHOR AFFILIATION: INGEOMINAS, Bogota, Colombia SO - SOURCE: Tectonophysics. 363; 3-4, Pages 159-180. 2003. PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 2003. CP - COUNTRY OF PUBLICATION: Netherlands PY - PUBLICATION YEAR: 2003 LA - LANGUAGE: English AB - ABSTRACT: The Tauramena (Colombia) earthquake, M (sub w) = 6.5, occurred on January 19, 1995, in the Andean Eastern Cordillera foothill region, the so-called Piedemonte Llanero. The Harvard CMT focal mechanism indicates an almost pure reverse fault rupture. There was no surface faulting associated with this earthquake. This event was located at the northern tip of a zone, about 90 km in length, with relatively low microseismic activity along the central segment of the Piedemonte Llanero in Colombia. A field expedition to the epicentral area was organized and a temporary portable network was installed for 1 month to register aftershock activity. More than 800 events were recorded during this period. A subset of the best located aftershocks (319 events) shows epicenters extended over an area of 800 km (super 2) , and suggests two antithetic planes on which most of the activity was concentrated. The main event and a subset of 41 aftershocks occurred before the installation of the portable network but were recorded by the Colombian National Seismic Network and were relocated. They show an epicentral distribution similar to that of the subsequent events. Based on geologic information, aftershock locations, and focal mechanisms, we built a model for the Tauramena earthquake. Our results indicate that the Tauramena earthquake was produced by reverse faulting along a steep-dipping plane (dip approximately 50 degrees NW) associated with the Guaicaramo System. The fault plane cuts through basement rocks and folded Mesozoic and Cenozoic sedimentary rocks. Distribution of aftershocks in depth, suggesting the presence of splay reverse faults and a backthrust, is consistent with the hypothesis that the Guaicaramo Fault System was an old Mesozoic normal fault, reactivated during the Andean compression as a reverse fault. Stress tensor inversion of P-wave first motion polarities was performed, and focal mechanisms for the best recorded aftershocks were calculated. We found a well-defined sub-horizontal principal compression axis oriented in the NW-SE direction. The predominant reverse faulting for the Tauramena earthquake and the stability of sigma (sub 1) suggest that the tectonics in the central segment of the Eastern Cordillera Frontal Fault System is dominated by a compressive regime orthogonal to the cordillera, the controlling processes being probably the Caribbean subduction and the Choco Block collision. DE - DESCRIPTORS: active-faults; aftershocks-; Andes-; body-waves; earthquakes-; Eastern-Cordillera; elastic-waves; epicenters-; fault-planes; faults-; field-studies; focal-mechanism; geometry-; Guaicaramo-Fault; inversion-tectonics; moment-tensors; normal-faults; P-waves; reactivation-; reverse-faults; rupture-; seismic-networks; seismic-waves; seismicity-; seismotectonics-; South-America; stress-; Tauramena-earthquake-1995; tectonics- CC - CATEGORY CODES: 19-Seismology DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic MC - MAP COORDINATES: LAT: N044200; N051800; LONG: W0724200; W0731200. NN - ANNOTATION: Includes appendix. IL - ILLUSTRATION: Refs: 42; illus. incl. sects., 1 table, sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands IS - ISSN: 0040-1951 CO - CODEN: TCTOAM AN - ACCESSION NUMBER: 2003-035218 UD - UPDATE CODE: 200311 Registro 380 de 5614 - GeoRef : 2002-2004/12 TI - TITLE: Application of tetracyclic polyprenoids as indicators of input from fresh-brackish water environments. AU - AUTHORS: Holba-A-G; Dzou-L-I; Wood-G-D; Ellis-L; Adam-P; Schaeffer-P; Albrecht-P; Greene-T; Hughes-W-B AF - AUTHOR AFFILIATION: Phillips Petroleum Company, Bartlesville, OK, United States SO - SOURCE: Organic Geochemistry. 34; 3, Pages 441-469. 2003. PB - PUBLISHER: Pergamon. Oxford-New York, International. 2003. CP - COUNTRY OF PUBLICATION: International PY - PUBLICATION YEAR: 2003 LA - LANGUAGE: English AB - ABSTRACT: C (sub 30) tetracyclic polyprenoids (TPP) are most prominently observed in samples derived from low salinity, i.e. fresh to brackish lacustrine environments, and are generally present in low levels in samples derived from saline, i.e., marine and saline lacustrine, environments. A near-shore facies of the Chonta Formation, Peru, that has no marine palynomorphs but abundant Chlorococcalean (Green) algal nonmarine palynomorphs, has high levels of TPP, suggesting Green algae (or Chlorophyta) are a possible source for the TPP compounds. The ratio between a C (sub 30) TPP compound and 27-norcholestanes is useful for assessing this nonmarine algal input. Moderate elevations of TPP, above what is common in marine derived samples, were found in ostensibly marine source rocks and oils from certain basins of western and northern South America (Middle Magdalena, Colombia; Maracaibo, Venezuela; and Trinidad basins). This is likely due to transport from the nonmarine to the marine environment because of an influx of fresh water into the near-shore marine environment. Alternatively, oils from these basins may have inputs from near-shore shallow marine algae with chemistry similar to that found in lacustrine settings. The TPP ratio, in conjunction with other environmental indicators such as 4-methyl steranes or hopane/sterane ratio, is useful for differentiating marine and nonmarine influences in pre-salt oils and source rocks of West Africa. The TPP ratio, used with other environmental indicators (gammacerane, C (sub 29) steranes, C (sub 30) steranes) and age diagnostic biomarkers (dinosteranes, 4-methylsteranes), can be useful in differentiating among nonmarine source facies. For example, in the Turpan-Hami basin, China, Permian saline lacustrine and Jurassic lacustrine deltaic facies can be discriminated. DE - DESCRIPTORS: Africa-; algae-; Antilles-; applications-; Argentina-; Asia-; biochemistry-; biomarkers-; brackish-water-environment; carbon-; Caribbean-region; Central-Africa; China-; Chlorophyta-; Chonta-Formation; Colombia-; Congo-; Coniacian-; Cretaceous-; Cuyo-Basin; Far-East; fresh-water-environment; Gabon-; geochemistry-; Hami-Basin; Jurassic-; Lesser-Antilles; Llanos-; Madre-de-Dios-Basin; Maracaibo-Basin; Maranon-Basin; Mesozoic-; microfossils-; Middle-Magdalena-Basin; Neuquen-Basin; organic-carbon; Oriente-Basin; palynomorphs-; Peru-; Plantae-; polyprenoids-; Putumayo-Basin; Santonian-; sea-level-changes; Senonian-; South-America; transgression-; Trinidad-; Trinidad-and-Tobago; Turpan-Basin; Ucayali-Basin; Upper-Cretaceous; Venezuela-; West-Africa; West-Indies; Xinjiang-China CC - CATEGORY CODES: 02A-General-geochemistry DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic NN - ANNOTATION: Includes two appendices. IL - ILLUSTRATION: Refs: 82; illus. incl. 5 tables, sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands IS - ISSN: 0146-6380 AN - ACCESSION NUMBER: 2003-035099 UD - UPDATE CODE: 200311 Registro 381 de 5614 - GeoRef : 2002-2004/12 BK - BOOK TITLE: Analyse multi-aleas et risques naturels dans le departement du Choco (nord-ouest de la Colombie) Translated Title: Multiple hazards and natural risk assessment in the Choco Department, northwestern Colombia. BA - BOOK AUTHORS: Mosquera-Machado-Silvia-del-Carmen SO - SOURCE: Terre and Environnement. 37; 2002. PB - PUBLISHER: Universite de Geneve, Section des Sciences de la Terre. Geneva, Switzerland. Pages: 159. 2002. CP - COUNTRY OF PUBLICATION: Switzerland PY - PUBLICATION YEAR: 2002 DG - DEGREE GRANTED: Doctoral DI - DEGREE GRANTING INSTITUTION: University of Geneva. Geneva, Switzerland. LA - LANGUAGE: French LS - LANGUAGE OF SUMMARY: English; Spanish DE - DESCRIPTORS: Choco-Colombia; Colombia-; earthquakes-; environmental-effects; floods-; geodynamics-; geologic-hazards; human-activity; hydrology-; mapping-; northwestern-Colombia; numerical-models; relief-; risk-assessment; seismic-risk; seismic-zoning; slope-stability; South-America CC - CATEGORY CODES: 22-Environmental-geology; 30-Engineering-geology DT - DOCUMENT TYPE: Serial; Thesis-or-Dissertation BL - BIB LEVEL: Monograph MC - MAP COORDINATES: LAT: N040000; N090000; LONG: W0754500; W0780000. IL - ILLUSTRATION: Refs: 52; illus. incl. 36 tables, sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. IS - ISSN: 1423-5773 AN - ACCESSION NUMBER: 2003-035051 UD - UPDATE CODE: 200311 Registro 382 de 5614 - GeoRef : 2002-2004/12 TI - TITLE: Transpressional tectonics of northern South America. AU - AUTHORS: Audemard-Felipe AF - AUTHOR AFFILIATION: PDVSA Exploracion, Caracas, Venezuela BK - BOOK TITLE: In: Geological Society of America, 2002 annual meeting. BA - BOOK AUTHORS: Anonymous SO - SOURCE: Abstracts with Programs - Geological Society of America. 34; 6, Pages 76. 2002. PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 2002. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 2002 CN - CONFERENCE INFORMATION: Geological Society of America, 2002 annual meeting. Denver, CO, United States. Oct. 27-30, 2002. LA - LANGUAGE: English AB - ABSTRACT: Along the northern margin of Venezuela from Colombia to Trinidad, lies an east-west range, (1,000X150 miles) which has been interpreted as an "Orogenic Float" developed by the interaction between oceanic crusts and the South-America's passive margin during late Cretaceous to Neogene times from west to east. These two distinct subduction zones play important roles in the geodynamic context: the "B" subduction of Lesser Antilles (west polarity) and coeval "B" Colombo-Venezuelan subduction (south polarity). Following, some examples that illustrate atypical structural styles formed in these domains: - The Barbados Accretionary Prism evolves over oceanic crust to the east and progressively rides continental crust towards the south. The prism is currently being disrupted by gravitational tectonics associated with the Orinoco Delta edifice. - The south vergent Mid-Miocene Serrania del Interior shows differential uplift due to remobilization of Miocene shales along its leading edge. - Orogenic collapse of the igneous-metamorphic "Caribbean allochthonous belt" and transpression superimposed to the Neogene sequence are caused by a transfer system between the two "B" subduction zones. - The Falcon anticlinorium resulted from partial inversion of a Neogene flexural basin, as opposed to the prevalent pull-apart model. It is actually overthrusted to the north, following the Present-day Colombo-Venezuelan Accretionary Prism. - Comments will be made on both the geodynamic setting of wrench tectonic models, e.g. the Bocono and Oca lineaments and "opposing" northwest vergence of the Merida and Perija folded belts. Implications for exploration will be discussed for all these structural styles. DE - DESCRIPTORS: accretionary-wedges; allochthons-; Andes-; Antilles-; Bocono-Lineament; Caribbean-region; Cenozoic-; Colombia-; Cretaceous-; crust-; Falcon-Anticlinorium; flexure-; geodynamics-; gravity-sliding; Lesser-Antilles; Mesozoic-; Neogene-; northern-South-America; Oca-Lineament; oceanic-crust; orogeny-; passive-margins; plate-tectonics; Serrania-del-Interior; Sierra-de-Perija; South-America; subduction-; subduction-zones; tectonics-; Tertiary-; transpression-; Trinidad-; Trinidad-and-Tobago; Upper-Cretaceous; Venezuela-; West-Indies CC - CATEGORY CODES: 16-Structural-geology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States IS - ISSN: 0016-7592 CO - CODEN: GAAPBC AN - ACCESSION NUMBER: 2003-035040 UD - UPDATE CODE: 200311 Registro 383 de 5614 - GeoRef : 2002-2004/12 TI - TITLE: Diversity in thrust-related hydrocarbon traps; not bad, just different. AU - AUTHORS: Kluth-Charles-Frederick; Richards-Kenneth; Phelps-James; Kveton-Kevin; Narr-Wayne AF - AUTHOR AFFILIATION: Kluth and Associates, Littleton, CO, United States BK - BOOK TITLE: In: Geological Society of America, 2002 annual meeting. BA - BOOK AUTHORS: Anonymous SO - SOURCE: Abstracts with Programs - Geological Society of America. 34; 6, Pages 76. 2002. PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 2002. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 2002 CN - CONFERENCE INFORMATION: Geological Society of America, 2002 annual meeting. Denver, CO, United States. Oct. 27-30, 2002. LA - LANGUAGE: English AB - ABSTRACT: Thrust structures form traps for hydrocarbons throughout the world. Many of the characteristics common to thrust belt structures were initially described in the North America. These relationships were then applied elsewhere, because "rules" of structural geometry are powerful interpretation guides where data is poor or sparse. Geometry of structural traps is largely controlled by the thickness and mechanical properties of the decollement zone, and by the mechanical stratigraphy of the hanging wall rocks. Pre-existing structure can also play a role. These factors are different in thrust belts around the world, so it is not surprising that structural geometries and histories are different than the "rules" developed in North America. In Papua New Guinea, the Darai Limestone is high in the section, underlain by thick shale units. The result is large, asymmetric detachment folds. In Bangladesh and Azerbaijan, the entire, thick section is mixed clastics and shortening takes place by symmetrical detachment folds. In Colombia, the hanging wall rocks are thick sections of metasediments that are equivalents of thinner, unmetamorphosed rocks in the footwall. These relationships form by thrust inversion of earlier rift basins. In deep water of passive margins, presence of a salt layer or overpressured shale controls geometry of thrust structures. The role of salt units in determining the width and thickness of thrust belts in cordilleran belts is well documented. The blind application of "rules" is not considered prudent. The recognition of the influence of the structural factors is critical to better predictive models of trap conditions and a better assessment of risk. DE - DESCRIPTORS: Asia-; Australasia-; Azerbaijan-; Bangladesh-; Colombia-; Commonwealth-of-Independent-States; controls-; crustal-shortening; Darai-Limestone; decollement-; Europe-; faults-; foot-wall; geometry-; hanging-wall; Indian-Peninsula; mechanical-properties; North-America; overpressure-; Papua-New-Guinea; passive-margins; petroleum-; plate-tectonics; risk-assessment; South-America; structural-traps; thickness-; thrust-faults; traps- CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources; 16-Structural-geology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States IS - ISSN: 0016-7592 CO - CODEN: GAAPBC AN - ACCESSION NUMBER: 2003-035039 UD - UPDATE CODE: 200311 Registro 384 de 5614 - GeoRef : 2002-2004/12 TI - TITLE: Submillennium-scale migrations of the rainforest-savanna boundary in Colombia; (super 14) C wiggle-matching and pollen analysis of core Las Margaritas. AU - AUTHORS: Wille-Michael; Hooghiemstra-Henry; van-Geel-Bas; Behling-Hermann; de-Jong-Arie; van-der-Borg-Klaas AF - AUTHOR AFFILIATION: University of Amsterdam, Department of Palynology and Paleo/Actuo-ecology, Amsterdam, Netherlands SO - SOURCE: Palaeogeography, Palaeoclimatology, Palaeoecology. 193; 2, Pages 201-223. 2003. PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 2003. CP - COUNTRY OF PUBLICATION: Netherlands PY - PUBLICATION YEAR: 2003 LA - LANGUAGE: English AB - ABSTRACT: We present the 11 150-cal-yr-long pollen record Laguna Las Margaritas (3 degrees 23'N, 73 degrees 26'W; 290 m altitude), located at a site sensitive to climatic change near the transition from the Amazonian rainforest to the savanna of the Llanos Orientales in Colombia. In the 10-m-long core nine AMS (super 14) C bulk samples show ages from 9760+ or -60 to 854+ or -36 BP and provide initial time control. Thirty-one additional AMS (super 14) C samples of selected macrofossils provide time control from 6250 to 4050 cal BP; for this interval precise time control was obtained by (super 14) C wiggle-match dating. From 11 150 to 9100 cal BP, grass savanna dominated the landscape while gallery forest along the drainage system was poorly developed. Water availability was lower than today and the length of the dry season longer. From 9100 to 7330 cal BP gallery forest expanded pointing to wetter conditions. From 7330 to 5430 cal BP savanna was increasingly replaced by forest, but with alternating abundance of both vegetation types. From 5430 to 2500 cal BP forest and wooded savanna dominated the western Llanos Orientales suggesting high precipitation rates. Expansion of Mauritia palm forest at 2500 cal BP reflects increasing water availability and stagnant water environments. Increasing savanna between 2500 and 1000 cal BP may represent a combined natural and anthropogenic signal. Development from open savanna to forest during the Middle Holocene is synchronous with a decreasing caloric seasonality, and a southward migration of the Intertropical Convergence Zone, suggesting that the large-scale climatic and vegetational change in the Colombian savannas is precession-forced. High-frequent migration of the savanna-rainforest boundary started around 6000 cal BP and continued at least to 3000 cal BP. Precipitation regimes in northwest and northeast South America seem opposite: dry conditions in the Colombian savanna area seem to reflect a La Nina setting of the climate system; wet conditions reflect an El Nino setting. Delta (super 14) C fluctuations reflect changes of solar activity and we tested the hypothesis that Delta (super 14) C fluctuations correspond to climatic and vegetational change. For the interval 6250 to 4050 cal BP, we applied (super 14) C wiggle-match dating (WMD), i.e. matching a series of radiocarbon ages in (super 14) C BP from the sediment, with the dendrochronology-based calibration curve, and we also wiggle-matched the pollen record vs. the Delta (super 14) C record. In this first attempt in a neotropical ecosystem, we could not find unambiguous support that changes in solar activity did trigger climatic and vegetational change in the savannas of the Llanos Orientales. DE - DESCRIPTORS: absolute-age; atmospheric-precipitation; C-14; carbon-; Cenozoic-; climate-change; Colombia-; cores-; dates-; ecosystems-; El-Nino-Southern-Oscillation; forests-; Holocene-; human-activity; isotopes-; Laguna-Las-Margaritas; lake-sediments; Llanos-; miospores-; paleoclimatology-; paleoecology-; paleohydrology-; palynomorphs-; pollen-; pollen-analysis; pollen-diagrams; Quaternary-; radioactive-isotopes; rain-forests; savannas-; seasonal-variations; sediments-; South-America; terrestrial-environment; vegetation- CC - CATEGORY CODES: 24-Quaternary-geology; 03-Geochronology DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic MC - MAP COORDINATES: LAT: N032300; N032300; LONG: W0732600; W0732600. IL - ILLUSTRATION: Refs: 61; illus. incl. charts, 2 tables, sketch map. Yüklə 20,82 Mb. Dostları ilə paylaş:
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