No. Registros Solicitud 1 5614 colombia
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CN - CONFERENCE INFORMATION: IX RPP; reuniao de paleobotanicos e palinologos. Guarulhos, Brazil. Dec. 9-12, 1997. LA - LANGUAGE: English DE - DESCRIPTORS: Brazil-; Cenozoic-; Colombia-; cores-; ecology-; ecosystems-; grasslands-; Holocene-; lake-sediments; Llanos-; Llanos-Orientales; miospores-; paleoclimatology-; paleoecology-; palynomorphs-; pollen-; pollen-analysis; Quaternary-; savannas-; sediments-; South-America; tropical-environment; upper-Quaternary; vegetation- CC - CATEGORY CODES: 24-Quaternary-geology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. IS - ISSN: 1413-3210 AN - ACCESSION NUMBER: 1999-069248 UD - UPDATE CODE: 199924 Registro 5477 de 5614 - GeoRef 1997-2001 BK - BOOK TITLE: Proceedings of the Ocean Drilling Program; Initial reports; Caribbean ocean history and the Cretaceous/ Tertiary boundary event; covering Leg 165 of the cruises of the Drilling Vessel JOIDES Resolution, Miami, Florida, to San Juan, Puerto Rico, sites 998-1002, 19 December 1995-17 February 1996. BA - BOOK AUTHORS: Sigurdsson-Haraldur; Leckie-R-Mark; Acton-Gary-D; Abrams-Lewis-J; Bralower-Timothy-J; Carey-Steven-N; Chaisson-William-P; Cotillon-Pierre; Cunningham-Andrew-D; D-Hondt-Steven-L; Droxler-Andre-W; Galbrun-Bruno; Gonzalez-Juan; Haug-Gerald; Kameo-Koji; King-John; Lind-Ida-L; Louvel-Veronique; Lyons-Timothy-W; Murray-Richard-W; Mutti-Maria; Myers-Greg; Pearce-Richard-B; Pearson-D-Graham; Peterson-Larry-C; Roehl-Ursula; Miller-Christine-M (editor); Maddox-Eva-M (editor) BF - BOOK AUTHOR AFFILIATION: University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, United States; University of Massachusetts, United States; Texas A&M University Research Park, United States; University of Puerto Rico, Puerto Rico; University of North Carolina, United States; Paleontological Research Institution, United States; Universite Lyon I, France; Rice University, United States; Universite Pierre et Marie Curie, France; GEOMAR, Federal Republic of Germany; Teikoku Oil Company, Japan; Danmarks Tekniske Universitet, Denmark; Institut Mediterraneen de Technologie, France; University of Missouri, Colombia, United States; Boston University, United States; Swiss Federal Institute of Technology, Switzerland; Columbia University, United States; University of Southampton, United Kingdom; Durham University, United Kingdom; University of Miami, United States; Bremen University, Federal Republic of Germany SO - SOURCE: Proceedings of the Ocean Drilling Program, Part A: Initial Reports. 165; 1997. PB - PUBLISHER: Texas A & M University, Ocean Drilling Program. College Station, TX, United States. Pages: 862. 1997. RP - RESEARCH PROGRAM: ODP (Ocean Drilling Program) CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 LA - LANGUAGE: English DE - DESCRIPTORS: Atlantic-Ocean; Caribbean-Sea; Cenozoic-; Cretaceous-; K-T-boundary; Leg-165; lower-Paleocene; Mesozoic-; North-Atlantic; Ocean-Drilling-Program; Paleocene-; Paleogene-; stratigraphic-boundary; Tertiary-; Upper-Cretaceous CC - CATEGORY CODES: 12-Stratigraphy DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Monograph MC - MAP COORDINATES: LAT: N103000; N193000; LONG: W0650000; W0830000. RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. IS - ISSN: 0884-5883 AN - ACCESSION NUMBER: 1999-067368 UD - UPDATE CODE: 199923 Registro 5478 de 5614 - GeoRef 1997-2001 TI - TITLE: Jurassic lava flow and volcaniclastic sequences from western Pangea and the Mesozoic rifting (Mexico and Northern Andes). AU - AUTHORS: Silva-Romo-Gilberto; Mendoza-Rosales-C; Hernandez-Rivero-M-P; Arellano-Gil-J AF - AUTHOR AFFILIATION: Universidad Nacional Autonoma de Mexico, Earth Science Engineering Division, Mexico City, Mexico BK - BOOK TITLE: In: Geological Society of America, South-Central Section, 31st annual meeting and Rocky Mountain Section, 50th annual meeting. BA - BOOK AUTHORS: Anonymous SO - SOURCE: Abstracts with Programs - Geological Society of America. 29; 2, Pages 46. 1997. PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 1997. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 CN - CONFERENCE INFORMATION: Geological Society of America, South-Central Section, 31st annual meeting and Rocky Mountain Section, 50th annual meeting. El Paso, TX, United States. March 20-21, 1997. LA - LANGUAGE: English DE - DESCRIPTORS: Andes-; Colombia-; Jurassic-; lava-flows; Mesozoic-; Mexico-; Northern-Andes; Pangaea-; rifting-; Sierra-de-Puebla; South-America; Tenexcate-Formation; volcaniclastics- CC - CATEGORY CODES: 05A-Igneous-and-metamorphic-petrology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. IS - ISSN: 0016-7592 CO - CODEN: GAAPBC AN - ACCESSION NUMBER: 1999-055968 UD - UPDATE CODE: 199919 Registro 5479 de 5614 - GeoRef 1997-2001 TI - TITLE: Evaluacion de imagenes de satelite SAR ERS-1 y spot-landsat en la cartografia de movimientos en masa Translated Title: Evaluation of SAR ERS-1 and SPOT-Landsat images for mapping mass movements. AU - AUTHORS: Vargas-Cuervo-G AF - AUTHOR AFFILIATION: INGEOMINAS, Ingenieria Geoambiental, Santafe de Bogota, Colombia BK - BOOK TITLE: In: The use and applications of ERS in Latin America--Uso y applicaciones de ERS en America Latina. CA - CORPORATE AUTHOR: European Space Agency, Paris, FRA; Pontificia Universidad Catolica de Chile, Santiago, Chile; Universidad Catolica de Valparaiso, Valparaiso, CHL; Germany, Deutsche Forschungsanstalt fuer Luft- und Raumfahrt, Cologne, Federal Republic of Germany; Spot Image, Toulouse, France SO - SOURCE: ESA SP. European Space Agency Special Publication. 405; Pages 109-118. 1997. PB - PUBLISHER: European Space Agency. Paris, International. 1997. CP - COUNTRY OF PUBLICATION: International PY - PUBLICATION YEAR: 1997 CN - CONFERENCE INFORMATION: International seminar on The use and applications of ERS in Latin America. Vina del Mar, Chile. Nov. 25-29, 1996. LA - LANGUAGE: Spanish LS - LANGUAGE OF SUMMARY: English AB - ABSTRACT: In order to evaluate the satellite image potential in mass movement mapping, methods were developed to compare morphodynamic maps obtained from: 1) stereoscope pair of Spot xs-Landsat TM image interpretation, 2) stereoscope pair of radar ERS-1 image interpretation, 3) field work based upon aerial photographs. The test area is located in the Colombian Eastern Cordillera in the high part of the Rio Chicamocha basin. From 458 mass movements, field mapped, 256 were identified using the stereoscope pair of Spot-Landsat. In addition, 43 non-identified mass movements were recognized and mapped using the stereoscope pair of Spot-Landsat and 7 using the ERS1 radar images. This work emphasizes the importance of field work in elaborating morphodynamic maps as well as it establishes satellite images to complement them; furthermore, it shows the advantages and failures of each method as a work tool. DE - DESCRIPTORS: Andes-; Colombia-; Eastern-Cordillera; ERS-1; imagery-; Landsat-; mapping-; mass-movements; radar-methods; remote-sensing; SAR-; satellite-methods; South-America; SPOT-; thematic-mapper CC - CATEGORY CODES: 23-Geomorphology; 20-Applied-geophysics DT - DOCUMENT TYPE: Serial; Conference-Document BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 6 RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique, Vandoeuvre-les-Nancy, France IS - ISSN: 0379-6566 IB - ISBN: 92-9092-303-2 AN - ACCESSION NUMBER: 1999-052972 UD - UPDATE CODE: 199918 Registro 5480 de 5614 - GeoRef 1997-2001 TI - TITLE: Glacier fluctuations in the eastern Andes of Colombia (South America) during the last 45,000 radiocarbon years. AU - AUTHORS: Helmens-K-F; Rutter-N-W; Kuhry-P AF - AUTHOR AFFILIATION: University of Lethbridge, Department of Geography, Lethbridge, AB, Canada BK - BOOK TITLE: In: Fluctuations of local glaciers 30-8 ka BP. BA - BOOK AUTHORS: Clapperton-Chalmers-M (editor) SO - SOURCE: Quaternary International. 38-39; Pages 39-48. 1997. PB - PUBLISHER: Pergamon. Oxford, United Kingdom. 1997. RP - RESEARCH PROGRAM: IGCP (International Geological Correlation Programme) CP - COUNTRY OF PUBLICATION: United-Kingdom PY - PUBLICATION YEAR: 1997 CN - CONFERENCE INFORMATION: Fluctuations of local glaciers 30-8 ka BP. Aberdeen, United Kingdom. May 21, 1994. LA - LANGUAGE: English DE - DESCRIPTORS: absolute-age; Andes-; C-14; carbon-; Cenozoic-; Colombia-; dates-; Eastern-Cordillera; fluctuations-; glacial-features; glaciation-; Holocene-; IGCP-; isotopes-; lacustrine-environment; lake-sediments; landforms-; moraines-; paleoclimatology-; peat-; Pleistocene-; Quaternary-; radioactive-isotopes; sediments-; Sierra-Nevada-del-Cocuy; South-America; variations- CC - CATEGORY CODES: 24-Quaternary-geology DT - DOCUMENT TYPE: Serial; Conference-Document BL - BIB LEVEL: Analytic NN - ANNOTATION: IGCP Project No. 253. IL - ILLUSTRATION: Refs: 22; illus. incl. sects., 3 tables, sketch maps. RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. IS - ISSN: 1040-6182 AN - ACCESSION NUMBER: 1999-051095 UD - UPDATE CODE: 199918 Registro 5481 de 5614 - GeoRef 1997-2001 BK - BOOK TITLE: Facies analysis of the upper Eocene La Paz Formation, and regional evaluation of the post-middle Eocene stratigraphy, northern middle Magdalena Valley basin, Colombia. BA - BOOK AUTHORS: Suarez-R-Mario-A CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 DG - DEGREE GRANTED: Master's DI - DEGREE GRANTING INSTITUTION: University of Colorado. Boulder, CO, United States. Pages: 88. 1997. LA - LANGUAGE: English AB - ABSTRACT: The La Paz Formation is upper Eocene in age and is the primary petroleum reservoir in the Provincia Field, located in the eastern foothills of the northern Middle Magdalena Valley Basin. The average thickness of the La Paz reservoir is 800 feet in the Provincia field. A facies analysis of this unit was conducted using 332 feet of core, which were calibrated with well logs, core petrophysical data, and used for well log facies associations predictions in 6 wells. Four facies associations are recognized and represent deposition in braided trunk channel, minor channel (distributary or crevasse), crevasse splay and floodplain subenvironments. The minor channel and crevasse splay deposits comprise avulsion deposits. The avulsion deposits are volumetrically important and comprise nearly half of the reservoir (49.1%). Recognition of significant avulsion deposits in this study suggests that channel avulsion and preservation of thick avulsion sequences may be common in braided stream settings and are not exclusively characteristic of meandering systems. The best reservoir facies in the La Paz Formation are subarkosic sandstones (porosity 16.7%, permeability 409.2 md), deposited in braided trunk channels and comprise 30.6% of the total reservoir thickness. Sandstone facies in the avulsion deposits have poor reservoir quality (porosity 12.9%, permeability 29 md) and act as fluid flow retardants (or lateral plugs). Floodplain deposits comprising 20.3% of the reservoir are impermeable and are the main vertical barriers. Based on the depositional model, a 2-D reservoir zonation was constructed for the La Paz reservoir. Six flow units were defined, ranging from 50 to 140 feet in thickness, each separated by floodplain deposits. Within the flow units, interbedded avulsion deposits and trunk channel deposits produce high reservoir heterogeneity. Understanding all of the depositional elements in this type of fluvial system has helped to create realistic reservoir characterization that could be applied to reservoir simulation models. The regional distribution of the post-middle Eocene units and the exploration potential of the La Paz Formation throughout the northern Middle Magdalena Valley Basin, has been evaluated using a chronostratigraphic framework. This was constructed from regional dip seismic profiles through the basin tied to well logs. The post-middle Eocene section of the northern Middle Magdalena Valley Basin is composed of six unconformity-bounded units (approximately 2nd order sequences) informally called "tectonosequences", because these units were caused mainly by tectonic activity in the basin. A younger tectonosequence 7 (Pliocene-Pleistocene) is recognized in the southern part of the basin but is not present in the study area (northern part of the basin) due to erosion. The unconformities that bound each tectonosequence developed during the accretion of Western Cordillera, the eastern migration of the Nazca and Caribbean Plates, and the collision of the Choco Block with the northwestern Colombian margin. The three oldest tectonosequences (upper Eocene-lower middle Miocene) were deposited in a foreland basin with sediment supply from the Central Cordillera and partially from the Santander massif, whereas the three youngest (upper middle Miocene-upper upper Miocene) were deposited in an intermontane basin with sediment supply from the Central Cordillera to the west and Eastern Cordillera and Santander massif to the east. The oldest tectonosequence (upper Eocene), comprises the La Paz and Esmeraldas formations. The La Paz Formation is the most important regional reservoir in the northern part and eastern foothills of the Middle Magdalena Valley Basin and has the greatest future exploration potential. The La Paz Formation is diachronous, being late Eocene in age in the western sector of the basin but only earliest late Eocene in age in the eastern sector. On the western margin of the basin, the La Paz Formation was deposited in alluvial fan systems, grading toward the east to braided fluvial deposits. In most of the central part of the basin, the La Paz Formation was not deposited because of the presence of the Sogamoso paleohigh. Onlapping reflections of La Paz Formation age are recognized on seismic profiles in the area of this paleotopographic feature. The Esmeraldas Formation both overlies the La Paz Formation and also laterally interfingers with it (across time lines). The Esmeraldas Formation is also a diachronous unit and is latest Eocene in age in the western part of the basin but spans most of the late Eocene in the eastern part of the basin. The results of the regional analysis conducted in this study suggest that the La Paz Formation could be involved in potential structural prospects related to reverse faulting in the eastern foothills of the northern Middle Magdalena Valley Basin. The drilling depths to the La Paz Formation in these prospects would range from 12,000 to 14,000 feet. DE - DESCRIPTORS: avulsion-; Cenozoic-; channels-; Colombia-; cores-; depositional-environment; Eocene-; floodplains-; fluvial-features; heterogeneity-; La-Paz-Formation; lithofacies-; Magdalena-Valley; middle-Eocene; oil-and-gas-fields; Paleogene-; permeability-; petroleum-; petroleum-exploration; porosity-; Provincia-Field; reservoir-rocks; South-America; stratigraphy-; structural-controls; Tertiary-; thickness-; unconformities-; upper-Eocene; well-logs CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources DT - DOCUMENT TYPE: Thesis-or-Dissertation BL - BIB LEVEL: Monograph IL - ILLUSTRATION: Refs: 42; illus. RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. AN - ACCESSION NUMBER: 1999-038150 UD - UPDATE CODE: 199913 Registro 5482 de 5614 - GeoRef 1997-2001 TI - TITLE: Lg-wave propagation in the South American Continent. AU - AUTHORS: Rial-J-R; Ritzwoller-M-H AF - AUTHOR AFFILIATION: University of North Carolina, Geology Department, Chapel Hill, NC, United States BK - BOOK TITLE: In: Seismological Society of America, Eastern Section, 68th annual meeting; program and abstracts. BA - BOOK AUTHORS: Anonymous SO - SOURCE: Seismological Research Letters. 68; 5, Pages 821. 1997. PB - PUBLISHER: Seismological Society of America, Eastern Section. [Berkeley, CA], United States. 1997. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 CN - CONFERENCE INFORMATION: Seismological Society of America, Eastern Section, 68th annual meeting. Chapel Hill, NC, United States. Oct. 6-8, 1996. LA - LANGUAGE: English DE - DESCRIPTORS: Chile-; Colombia-; earthquakes-; elastic-waves; Lg-waves; Peru-; propagation-; seismic-networks; seismic-waves; seismicity-; South-America; surface-waves CC - CATEGORY CODES: 19-Seismology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. IS - ISSN: 0895-0695 CO - CODEN: #02565 AN - ACCESSION NUMBER: 1999-019377 UD - UPDATE CODE: 199907 Registro 5483 de 5614 - GeoRef 1997-2001 TI - TITLE: Structural framework, styles and evolution of the Eastern Cordillera, Colombia. AU - AUTHORS: Schelling-Daniel-D; Allen-Richardson-B; Schamel-Steven AF - AUTHOR AFFILIATION: University of Utah, Energy & Geoscience Institute, Salt Lake City, UT, United States BK - BOOK TITLE: In: Geological Society of America, 1997 annual meeting. BA - BOOK AUTHORS: Anonymous SO - SOURCE: Abstracts with Programs - Geological Society of America. 29; 6, Pages 225. 1997. PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 1997. CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 CN - CONFERENCE INFORMATION: Geological Society of America, 1997 annual meeting. Salt Lake City, UT, United States. Oct. 20-23, 1997. LA - LANGUAGE: English DE - DESCRIPTORS: Andes-; balanced-cross-sections; basement-tectonics; block-structures; Cobardes-Arcabuco-Uplift; Colombia-; contraction-; cross-sections; crustal-shortening; deformation-; Eastern-Cordillera; faults-; fold-and-thrust-belts; grabens-; half-grabens; hanging-wall; Llanos-; Magdalena-Valley; normal-faults; Quetame-Massif-Cocuy-Uplift; Sabana-de-Bogota; South-America; systems-; tectonics-; thin-skinned-tectonics; thrust-faults; Villeta-Portones-Uplift CC - CATEGORY CODES: 16-Structural-geology DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document BL - BIB LEVEL: Analytic RF - REFERENCE SOURCE: GeoRef, Copyright 2002, 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: 1999-005303 UD - UPDATE CODE: 199903 Registro 5484 de 5614 - GeoRef 1997-2001 TI - TITLE: New and less known Barremian-Albian Ammonites from Colombia. AU - AUTHORS: Kakabadze-Mikhail-V; Hoedemaeker-Philip-J AF - AUTHOR AFFILIATION: Academy of Sciences, Geological Institute, Tbilisi, Georgian Republic SO - SOURCE: Scripta Geologica. 114; Pages 57-117. 1997. PB - PUBLISHER: Rijksmuseum van Geologie en Mineralogie. Leiden, Netherlands. 1997. CP - COUNTRY OF PUBLICATION: Netherlands PY - PUBLICATION YEAR: 1997 LA - LANGUAGE: English DE - DESCRIPTORS: Albian-; Ammonoidea-; assemblages-; Barremian-; Cephalopoda-; Colombia-; Cretaceous-; Criceratites-; faunal-provinces; Invertebrata-; Lower-Cretaceous; measurement-; Mesozoic-; Mollusca-; morphology-; new-taxa; preservation-; South-America; taxonomy-; Tetrabranchiata- CC - CATEGORY CODES: 10-Invertebrate-paleontology DT - DOCUMENT TYPE: Serial BL - BIB LEVEL: Analytic IL - ILLUSTRATION: Refs: 52; illus. incl. 16 plates. RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. IS - ISSN: 0375-7587 CO - CODEN: SCGLA5 AN - ACCESSION NUMBER: 1998-073000 UD - UPDATE CODE: 199824 Registro 5485 de 5614 - GeoRef 1997-2001 BK - BOOK TITLE: Thermomechanical modeling of the Llanos Basin, Colombia, South America. BA - BOOK AUTHORS: Cardozo-Nestor CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 DG - DEGREE GRANTED: Master's DI - DEGREE GRANTING INSTITUTION: Ohio University, Athens. Athens, OH, United States. Pages: 158. 1997. LA - LANGUAGE: English AB - ABSTRACT: A thermomechanical model was implemented to approximate the evolution of the Llanos Basin, located at the eastern side of the Colombian Andes. The model consists of two finite element codes that estimate the deformation of a lithospheric elastic plate and its cooling and contraction. The initial geometry and thermal state of the plate are defined by a uniform extension model (McKenzie, 1978). Additional constraints include the lithospheric rheology and density parameters, the decompacted sediment properties for the time under consideration, and the history of topography of the loads from paleogeographic interpretations and palinspastic restorations (Cooper et al., 1995). The model results support the hypothesis that the Llanos Basin subsidence was mainly controlled by the flexural deformation of a thermally stable lithosphere. With an elastic thickness of 70 km, the evolution of the Llanos Basin and the adjacent orogens was well replicated. Minor limitations of the model can be explained by changes in sea level and activity along the Cusiana and Guaicaramo faults. For the Colombian Andes, the results show that there is little coupling between the Eastern and the Central Cordilleras. DE - DESCRIPTORS: Andes-; basin-analysis; Colombia-; deformation-; density-; elastic-properties; flexure-; lithosphere-; Llanos-; models-; rheology-; South-America; subsidence-; thermomechanical-properties; thickness- CC - CATEGORY CODES: 16-Structural-geology DT - DOCUMENT TYPE: Thesis-or-Dissertation BL - BIB LEVEL: Monograph IL - ILLUSTRATION: Refs: 51; illus. RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. AN - ACCESSION NUMBER: 1998-069590 UD - UPDATE CODE: 199824 Registro 5486 de 5614 - GeoRef 1997-2001 BK - BOOK TITLE: Geochemical and isotopic record of climate fluctuations during the middle to late Pleistocene in lacustrine deposits from the Sabana de Bogota Basin, Colombia. BA - BOOK AUTHORS: Mora-P-German CP - COUNTRY OF PUBLICATION: United-States PY - PUBLICATION YEAR: 1997 DG - DEGREE GRANTED: Master's DI - DEGREE GRANTING INSTITUTION: Indiana University, Bloomington. Bloomington, IN, United States. Pages: 43. 1997. LA - LANGUAGE: English AB - ABSTRACT: Continuous lacustrine deposits in the Sabana de Bogota basin (Colombia) record cyclic climatic variations during the Pleistocene. The Funza-II core, drilled in this intermontane basin, provides an opportunity to assess the influence of glacial/interglacial climate changes on equatorial South America. Previous studies on pollen in massive clays and muds of the Funza-II core showed oscillations of the Andean forest line closely coupled to orbital patterns in marine oxygen-isotope records. The biogeochemical response to climate is investigated by analyzing organic carbon (Corg) and sulfur contents, and the carbon isotopic composition of organic matter (delta (super 13) Corg) in the first 120 m ( approximately 28 to 550 ka) of the Funza-II core. Biogeochemical parameters in the Funza-II record exhibit a strong cyclicity characterized by high amplitude variation in the sub-Milankovitch band. There is strong covariance in the Corg and pollen records. Decreases in Corg and S tend to occur in glacial intervals and are usually associated with a pronounced shift to isotopic values characteristic of C (sub 4) grassland. Despite the high variability in the delta (super 13) Corg record, a roughly linear decrease in delta (super 13) Corg values is observed with depth. In the lower part of the study interval, these data suggest inputs predominantly from C (sub 3) plants in interglacial intervals. Contributions from lacustrine algae to the bulk organic matter are also indicated. The cumulative records indicate that the relative contribution of terrestrial and lacustrine organic matter varied cyclically with two to six cycles in each major interglacial interval. Yüklə 20,82 Mb. Dostları ilə paylaş:
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