No. Registros Solicitud 1 5614 colombia

BL - BIB LEVEL: Analytic

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States

IS - ISSN: 0094-0038

CO - CODEN: APGAB2

AN - ACCESSION NUMBER: 2003-023664

UD - UPDATE CODE: 200308

Registro 463 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: The Cusiana Field, Llanos foothills, Colombia; lessons learned from the rapid development of a giant oil field.

AU - AUTHORS: Warren-Edward-A; Mitchell-A; Estrada-C; Merrill-R-C; Leel-W; Hervochon-J; Pulido-O

AF - AUTHOR AFFILIATION: BPX Colombia, Bogota, Colombia

BK - BOOK TITLE: In: American Association of Petroleum Geologists 2001 annual meeting.

BA - BOOK AUTHORS: Anonymous

SO - SOURCE: Annual Meeting Expanded Abstracts - American Association of Petroleum Geologists. 2001; Pages 210-211. 2001.

PB - PUBLISHER: American Association of Petroleum Geologists and Society of Economic Paleontologists and Mineralogists. Tulsa, OK, United States. 2001.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 2001

CN - CONFERENCE INFORMATION: American Association of Petroleum Geologists 2001 annual meeting. Denver, CO, United States. June 3-6, 2001.

LA - LANGUAGE: English

AB - ABSTRACT: The Cusiana Field is a giant oilfield located in the Llanos Foothills of Colombia and comprises three sandstone reservoirs: Eocene Mirador, Paleocene Barco and Cretaceous Guadalupe. All contain light, compositionally variable oil with associated gas. Discovered in 1992, the Cusiana Field was sanctioned for fast-track development in 1993 and, despite the security problems of the country, was successfully brought on to production in 1995 when the 1.2 bcfd gas re-injection facility started-up. Peak production of 310 mbopd was achieved in 1998. 400 million barrels of production, 72 wells and a 3D seismic survey later have yielded surprises, experience and learning relevant to complex development projects elsewhere. Initially, poor reservoir communication and early water and gas breakthrough into producers were considered serious risks. Detailed sedimentological descriptions were made and a long-term test, coupled with aggressive static and dynamic pressure monitoring, was initiated. Last described in 1995, subsequent experience has shown that a simpler reservoir description resulting from the integration of high-resolution biostratigraphy, sedimentology, geochemistry and fracture studies with pressure and tracer data has been more successful in describing fluid movement than the earlier sedimentological-based descriptions and has greatly simplified the task of modelling the dynamic reservoir behavior. The structural complexity revealed by well and 3D seismic data is greater than original interpretations, resulting in a better quality original oil-in-place estimate associated with a complex frontal imbricate and multiple oil-water contacts. Among the lessons learned to date is that long-term-testing is very useful for demonstrating fieldwide connectivity but it can lead to difficulty in unequivocal identification of original oil-water-contacts. The greatest development challenges are not necessarily those originally predicted during the appraisal phase so a balanced technical program is likely to be more successful than one focused at perceived, but not necessarily critical, issues.

DE - DESCRIPTORS: Barco-Formation; biostratigraphy-; Cenozoic-; clastic-rocks; Colombia-; Cretaceous-; Cusiana-Field; development-; Eocene-; fractures-; geochemistry-; geophysical-methods; geophysical-surveys; giant-fields; Guadalupe-Formation; history-; Llanos-; Mesozoic-; Mirador-Formation; monitoring-; natural-gas; oil-and-gas-fields; oil-wells; oil-water-interface; Paleocene-; Paleogene-; petroleum-; production-; sandstone-; sedimentary-rocks; seismic-methods; South-America; surveys-; Tertiary-; testing-; three-dimensional-models; water-

CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources

DT - DOCUMENT TYPE: Abstract; Serial; Conference-Document

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N050000; N052000; LONG: W0723000; W0725000.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States

IS - ISSN: 0094-0038

CO - CODEN: APGAB2

AN - ACCESSION NUMBER: 2003-023632

UD - UPDATE CODE: 200308

Registro 464 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: 2-D thermal and kinematic modeling of the Cordillera Oriental, Colombia.

AU - AUTHORS: Toro-Jaime; Lecornec-Lance-Sophie; Bordas-le-Floch-Nathalie; Roure-Francois; Sassi-William

AF - AUTHOR AFFILIATION: West Virginia University, Morgantown, WV, United States

BK - BOOK TITLE: In: American Association of Petroleum Geologists 2001 annual meeting.

BA - BOOK AUTHORS: Anonymous

SO - SOURCE: Annual Meeting Expanded Abstracts - American Association of Petroleum Geologists. 2001; Pages 201. 2001.

PB - PUBLISHER: American Association of Petroleum Geologists and Society of Economic Paleontologists and Mineralogists. Tulsa, OK, United States. 2001.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 2001

CN - CONFERENCE INFORMATION: American Association of Petroleum Geologists 2001 annual meeting. Denver, CO, United States. June 3-6, 2001.

LA - LANGUAGE: English

AB - ABSTRACT: We modeled the kinematic evolution of two regional-scale transects through the Cordillera Oriental fold-and-thrust belt and then calculated the conductive thermal state of key steps of the kinematic history using THRUSTPACK 4.0. The models were constrained by well, seismic, apatite fission track, and thermal maturity data provided by the members of the SUBTRAP consortium managed by IFP. The main compressional structures in the Cordillera are controlled by Jurassic-Early normal faults of the Bogota Basin and the paleo-Magdalena Basin. The thermal evolution is strongly influence by the location of Mesozoic extensional basins. Although shortening started in the Latest Cretaceous, the bulk of the deformation took place during the Miocene to Recent Andean phase. Rocks in different structural positions within the thrust belt follow different time-temperature paths. The internal part of the Cordillera had high heat flow, with peak sedimentary burial and peak maturation during the Paleocene to Oligocene flexural phase followed by Andean uplift and denudation. In contrast, the Llanos Foothills are characterized by continued flexural subsidence and syntectonic sedimentation up to the present time. Thermal maturation results from the combination of syntectonic sedimentation and tectonic burial. Finally, the thermal regime of the western flank of the Cordillera is cooler than the interior of the range while the structural history is more complex. Along our transect an active kitchen is located in the west-vergent thrust belt of the Cordillera Oriental. In the Magdalena Valley there are be local kitchens only where a thick stratigraphic section is preserved.

DE - DESCRIPTORS: Andes-; Bogota-Basin; Cenozoic-; Colombia-; compression-tectonics; Cretaceous-; crustal-shortening; denudation-; Eastern-Cordillera; extension-tectonics; faults-; flexure-; fold-and-thrust-belts; heat-flow; kinematics-; Llanos-; Magdalena-Basin; Magdalena-Valley; maturity-; Mesozoic-; Miocene-; models-; Neogene-; normal-faults; sedimentation-; South-America; structural-controls; tectonics-; Tertiary-; THRUSTPACK-4.0; two-dimensional-models; uplifts-; Upper-Cretaceous

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 American Association of Petroleum Geologists, Tulsa, OK, United States

IS - ISSN: 0094-0038

CO - CODEN: APGAB2

AN - ACCESSION NUMBER: 2003-023599

UD - UPDATE CODE: 200308

Registro 465 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Evolution of the Cretaceous organic facies in Colombia; implications for oil composition.

AU - AUTHORS: Ramon-J-C; Dzou-L-I; Hughes-W-B; Holba-A-G

AF - AUTHOR AFFILIATION: ARCO International Oil and Gas Company, Plano, TX, United States

SO - SOURCE: Journal of South American Earth Sciences. 14; 1, Pages 31-50. 2001.

PB - PUBLISHER: Pergamon. Oxford, United Kingdom. 2001.

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 2001

LA - LANGUAGE: English

DE - DESCRIPTORS: chemical-composition; Colombia-; Cretaceous-; diagenesis-; lithofacies-; Magdalena-Colombia; Mesozoic-; organic-compounds; petroleum-; sedimentary-rocks; source-rocks; South-America

CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources; 02C-Geochemistry-of-rocks,-soils,-and-sediments

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N074200; N112300; LONG: W0730000; W0745500.

IL - ILLUSTRATION: Refs: 46; illus. incl. 3 tables, geol. sketch map.

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

IS - ISSN: 0895-9811

AN - ACCESSION NUMBER: 2003-023238

UD - UPDATE CODE: 200308

Registro 466 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: The "Eje Cafetero" earthquake, Colombia, of January 25, 1999.

AU - AUTHORS: Restrepo-J-I; Cowan-H-A

AF - AUTHOR AFFILIATION: University of Canterbury, Department of Civil Engineering, Christchurch, New Zealand

SO - SOURCE: Bulletin of the New Zealand National Society for Earthquake Engineering. 33; 1, Pages 1-29. 2000.

PB - PUBLISHER: New Zealand National Society for Earthquake Engineering. Wellington, New Zealand. 2000.

CP - COUNTRY OF PUBLICATION: New-Zealand

PY - PUBLICATION YEAR: 2000

LA - LANGUAGE: English

AB - ABSTRACT: A moderate shallow earthquake struck the west central region of Colombia on 25 January 1999. The earthquake caused damage of approximately NZ $3.7 billion (US $1.9 billion), 1,230 deaths. About 200,000 people were made homeless. The level of damage and losses can be attributed to the shallow focus of the earthquake and its proximity to the major towns, together with topographical effects and soft soil conditions, which amplified the ground motions in some areas. The lack of a well coordinated, national emergency response strategy, and the severe impact of the event on the organisations and key individuals responsible for managing the emergency response in the affected area, impaired the emergency response in the aftermath. This paper summarises the main findings of a reconnaissance team to the region organised by the New Zealand Society for Earthquake Engineering.

DE - DESCRIPTORS: Colombia-; damage-; earthquakes-; Eje-Cafetero-earthquake-1999; emergency-response; geologic-hazards; ground-motion; shallow-focus-earthquakes; soil-mechanics; South-America; strength-; strong-motion; topography-

CC - CATEGORY CODES: 30-Engineering-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 26; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data supplied by Institute of Geological and Nuclear Sciences (SIRIS), Lower Hutt, New Zealand

IS - ISSN: 0110-0718

CO - CODEN: #50290

AN - ACCESSION NUMBER: 2003-022965

UD - UPDATE CODE: 200308

Registro 467 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Accreted fragments of the Late Cretaceous Caribbean-Colombian Plateau in Ecuador.

AU - AUTHORS: Mamberti-Marc; Lapierre-Henriette; Bosch-Delphine; Jaillard-Etienne; Ethien-Raynald; Hernandez-Jean; Polve-Mireille

AF - AUTHOR AFFILIATION: Universite de Lausanne, IMP, Lausanne, Switzerland

SO - SOURCE: Lithos. 66; 3-4, Pages 173-199. 2003.

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

CP - COUNTRY OF PUBLICATION: International

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: The eastern part of the Western Cordillera of Ecuador includes fragments of an Early Cretaceous ( nearly equal 123 Ma) oceanic plateau accreted around 85-80 Ma (San Juan-unit). West of this unit and in fault contact with it, another oceanic plateau sequence (Guaranda unit) is marked by the occurrence of picrites, ankaramites, basalts, dolerites and shallow level gabbros. A comparable unit is also exposed in northwestern coastal Ecuador (Pedernales unit). Picrites have LREE-depleted patterns, high epsilon Nd (sub i) and very low Pb isotopic ratios, suggesting that they were derived from an extremely depleted source. In contrast, the ankaramites and Mg-rich basalts are LREE-enriched and have radiogenic Pb isotopic compositions similar to the Galapagos HIMU component; their epsilon Nd (sub i) are slightly lower than those of the picrites. Basalts, dolerites and gabbros differ from the picrites and ankaramites by flat rare earth element (REE) patterns and lower epsilon Nd; their Pb isotopic compositions are intermediate between those of the picrites and ankaramites. The ankaramites, Mg-rich basalts, and picrites differ from the lavas from the San Juan-Multitud Unit by higher Pb ratios and lower epsilon Nd (sub i) . The Ecuadorian and Gorgona 88-86 Ma picrites are geochemically similar. The Ecuadorian ankaramites and Mg-rich basalts share with the 92-86 Ma Mg-rich basalts of the Caribbean-Colombian Oceanic Plateau (CCOP) similar trace element and Nd and Pb isotopic chemistry. This suggests that the Pedernales and Guaranda units belong to the Late Cretaceous CCOP. The geochemical diversity of the Guaranda and Pedernales rocks illustrates the heterogeneity of the CCOP plume source and suggests a multi-stage model for the emplacement of these rocks. Stratigraphic and geological relations strongly suggest that the Guaranda unit was accreted in the late Maastrichtian ( nearly equal 68-65 Ma).

DE - DESCRIPTORS: accreting-plate-boundary; accretion-; alkaline-earth-metals; Andes-; basalts-; Caribbean-Plate; Caribbean-region; Central-America; chemical-composition; Colombia-; Cretaceous-; crust-; diabase-; Ecuador-; gabbros-; Guaranda-Unit; igneous-rocks; isotope-ratios; lead-; major-elements; Mesozoic-; metals-; models-; neodymium-; oceanic-crust; Pedernales-Unit; picrite-; plate-tectonics; plutonic-rocks; rare-earths; San-Juan-Unit; sedimentary-rocks; South-America; spectra-; stratigraphic-units; strontium-; tectonostratigraphic-units; trace-elements; volcanic-rocks; Western-Cordillera; X-ray-fluorescence-spectra

CC - CATEGORY CODES: 18-Solid-earth-geophysics

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: S030000; N010000; LONG: W0780000; W0810000.

IL - ILLUSTRATION: Refs: 59; illus. incl. sect., 3 tables, geol. sketch maps.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

IS - ISSN: 0024-4937

CO - CODEN: LITHAN

AN - ACCESSION NUMBER: 2003-022390

UD - UPDATE CODE: 200308

Registro 468 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Late-glacial and Holocene history of the dry forest area in the South Colombian Cauca Valley.

AU - AUTHORS: Berrio-Juan-Carlos; Hooghiemstra-Henry; Marchant-Robert; Rangel-Orlando

AF - AUTHOR AFFILIATION: University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics (IBED), Amsterdam, Netherlands

SO - SOURCE: JQS. Journal of Quaternary Science. 17; 7, Pages 667-682. 2002.

PB - PUBLISHER: John Wiley and Sons for the Quaternary Research Association. Chichester, United Kingdom. 2002.

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 2002

LA - LANGUAGE: English

AB - ABSTRACT: Two sedimentary cores with pollen, charcoal and radiocarbon data are presented. These records document the Late-glacial and Holocene dry forest vegetation, fire and environmental history of the southern Cauca Valley in Colombia (1020 m). Core Quilichao-1 (640 cm; 3 degrees 6'N, 76 degrees 31'W) represents the periods of 13 150-7720 (super 14) C yr BP and, following a hiatus, from 2880 (super 14) C yr BP to modern. Core La Teta-2 (250 cm; 3 degrees 5'N, 76 degrees 32'W) provides a continuous record from 8700 (super 14) C yr BP to modern. Around 13150 (super 14) C yr BP core Quilichao-1 shows an active Late-glacial drainage system and presence of dry forest. From 11465 to 10520 (super 14) C yr BP dry forest consists mainly of Crotalaria, Moraceae/Urticaceae, Melastomataceae/Combretaceae, Piper and low stature trees, such as Acalypha, Alchornea, Cecropia and Celtis. At higher elevation Andean forest comprising Alnus, Hedyosmum, Quercus and Myrica was common. After 10520 (super 14) C yr BP the floral composition of dry forest changed, with extensive open grass vegetation indicative of dry climatic conditions. This event may coincide with the change to cool and dry conditions in the second part of the El Abra stadial, an equivalent to the Younger Dryas. From 8850 (super 14) C yr BP the record from La Teta indicates dry climatic conditions relative to the present, these prevailing up to 2880 (super 14) C yr BP at Quilichao and to 2720 (super 14) C yr BP at La Teta. Severe dryness reached maxima at 7500 (super 14) C yr BP and 4300 (super 14) C yr BP, when dry forest reached maximum expansion. Dry forest was gradually replaced by grassy vegetation, reaching maximum expansion around 2300 (super 14) C yr BP. After 2300 (super 14) C yr BP grassy vegetation remains abundant. Presence of crop taxa (a.o. Zea mays), disturbance indicators (Cecropia) and an increase in charcoal point to the presence of pre-Columbian people since 2300 (super 14) C yr BP. After 950 (super 14) C yr BP, expansion of secondary forest taxa may indicate depopulation and abandonment of previously cultivated land. After 400 (super 14) C yr BP, possibly related to the Spanish conquest, secondary forest expanded and charcoal concentrations increased, possibly indicating further reduction of cultivated land. During the past century, Heliotropium and Didymopanax became abundant in an increasingly degraded landscape. Abstract Copyright (2002), Wiley Periodicals, Inc.

DE - DESCRIPTORS: absolute-age; accelerator-mass-spectra; basins-; C-14; carbon-; Cauca-Valley; Cenozoic-; charcoal-; Colombia-; cores-; dates-; ecosystems-; floral-list; forests-; glacial-environment; Holocene-; human-activity; isotopes-; mass-spectra; miospores-; paleoclimatology-; paleoecology-; palynomorphs-; Plantae-; Pleistocene-; pollen-; pollen-diagrams; Quaternary-; radioactive-isotopes; refugia-; sedimentary-basins; South-America; spectra-; terrestrial-environment; trees-; upper-Pleistocene; upper-Weichselian; vegetation-; Weichselian-; Younger-Dryas

CC - CATEGORY CODES: 24-Quaternary-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N030600; N030600; LONG: W0763100; W0763100.

LAT: N030500; N030500; LONG: W0763200; W0763200.

IL - ILLUSTRATION: Refs: 50; illus. incl. sects., 2 tables, sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2003, American Geological Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom

IS - ISSN: 0267-8179

AN - ACCESSION NUMBER: 2003-022274

UD - UPDATE CODE: 200308

Registro 469 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Evolution of the Archaean crust by delamination and shallow subduction.

AU - AUTHORS: Foley-Stephen-F; Buhre-Stephan; Jacob-Dorrit-E

AF - AUTHOR AFFILIATION: Universitaet Greifswald, Institut fuer Geologische Wissenschaften, Greifswald, Federal Republic of Germany

SO - SOURCE: Nature (London). 421; 6920, Pages 249-252. 2003.

PB - PUBLISHER: Macmillan Journals. London, United Kingdom. 2003.

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

DE - DESCRIPTORS: Archean-; basalts-; Colombia-; crust-; cumulates-; delamination-; eclogite-; experimental-studies; feldspar-group; framework-silicates; gabbros-; geochemistry-; Gorgona-Island; granulites-; heat-flow; high-pressure; igneous-rocks; lava-; lower-crust; mantle-; metamorphic-rocks; metamorphism-; mid-ocean-ridge-basalts; mid-ocean-ridges; mineral-assemblages; ocean-floors; oceanic-crust; picrite-; plagioclase-; plate-tectonics; plutonic-rocks; Precambrian-; pressure-; pyroxenite-; shallow-depth; silicates-; slabs-; South-America; subduction-; transformations-; ultramafics-; upper-mantle; volcanic-rocks

CC - CATEGORY CODES: 18-Solid-earth-geophysics; 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N030000; N030000; LONG: W0781900; W0781900.

IL - ILLUSTRATION: Refs: 30; illus. incl. 1 table.

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

IS - ISSN: 0028-0836

CO - CODEN: NATUAS

AN - ACCESSION NUMBER: 2003-021771

UD - UPDATE CODE: 200307

Registro 470 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Controls on architecture of the Late Cretaceous to Cenozoic southern Middle Magdalena Valley Basin, Colombia.

AU - AUTHORS: Gomez-Elias; Jordan-Teresa-E; Allmendinger-Richard-W; Hegarty-Kerry; Kelley-Shari; Heizler-Matthew

AF - AUTHOR AFFILIATION: Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY, United States

SO - SOURCE: Geological Society of America Bulletin. 115; 2, Pages 131-147. 2003.

PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 2003.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: The Maastrichtian-Cenozoic southern Middle Magdalena Valley Basin of Colombia contains a unique record of unconformities, strata, and structure, from which we extract the histories of exhumation of the Central Cordillera, to the west, and evolution of the Eastern Cordillera fold-and-thrust belt, to the east. This study integrates field-based analyses of stratigraphy, laboratory analyses of provenance, fission-track thermochronology, vitrinite-reflectance data, volcanic-ash geochronology, and studies of synorogenic geometries and structure displayed in seismic data. A major unconformity, the Middle Magdalena Valley unconformity, formed by eastward migration of Central Cordillera uplift during Late Cretaceous to early Eocene time, which transformed a Maastrichtian marine basin into a Paleocene depositional piedmont area. This transformation is recorded by a coarsening-upward sequence of marine shales to alluvial-fan conglomerates, which was partly eroded during further early Eocene propagation of Central Cordillera deformation. Cessation of this phase of uplift led to formation of a pediment surface, the Middle Magdalena Valley unconformity, which was buried by westward-onlapping middle Eocene to Neogene alluvial deposits. Middle Eocene to Neogene facies, paleoflow, and unconformities were controlled by Eastern Cordillera deformation. In the Eastern Cordillera foothills, growth strata and thermal history reveal two phases of folding of middle Eocene-Oligocene and late Miocene ages, prior to intense Pliocene-Pleistocene uplift. Two unconformities of early late Miocene and Pliocene-Pleistocene ages occur to the west of the Eastern Cordillera and record flexural tilting related to episodes of Eastern Cordillera loading.