No. Registros Solicitud 1 5614 colombia

SO - SOURCE: Geologia Colombiana. 27; Pages 27-49. 2002.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 2002.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 2002

LA - LANGUAGE: English

LS - LANGUAGE OF SUMMARY: Spanish

AB - ABSTRACT: The Barremian to Maastrichtian interval of the sedimentary succession from the Cretaceous Colombian Basin is divided in stratigraphic sequences and in several allostratigraphic units, which include the Fomeque, Une, and Chipaque Alloformations, the Guadalupe Allogroup, and the lower part of the Guaduas Alloformation. The division is based on the recognition of regional surfaces of sedimentological discontinuity, corresponding mainly to Transgressive Surfaces (TS) located at the base of Transgressive Systems Tracts (TST), and Regressive Surfaces (RS) coincident with Sequence Boundaries (SB) and located at the base of Regressive Systems Tracts (RST). The proposed allostratigraphic units are composed of facies belts, which extend across the whole basin and include laterally adjacent and essentially synchronous lithostratigraphic units. The base of the Fomeque Alloformation is located on the Transgressive Surface (TS) at the Hauterivian/Barremian boundary. The base of the Une Alloformation is located on the Regressive Surface (RS) at the Aptian/Albian boundary. The base of the Chipaque Alloformation on the Transgressive Surface (TS) at the Cenomanian/Turonian boundary, and the base of the Guadalupe Allogroup on the Regressive Surface (RS) at the Santonian/Campanian boundary. The Une Alloformation is subdivided in allomembers, using the Transgressive Surface (TS) at the Lower Albian/Middle Albian boundary and the Regressive Surface (RS) at the Albian/Cenomanian boundary. In the same way, the Guadalupe Allogroup is subdivided in the Lower, Middle, and Upper Guadalupe Alloformations, using the Transgressive Surface (TS) at the Lower Campanian/Upper Campanian boundary and the Regressive Surface (RS) at the Campanian/Maastrichtian boundary. The succession is capped by the lower part of the Guaduas Alloformation, which is located over the Transgressive Surface (TS) at the Lower Maastrichtian/Upper Maastrichtian boundary.

DE - DESCRIPTORS: allostratigraphy-; Ammonoidea-; Andes-; assemblages-; back-arc-basins; Barremian-; basins-; biostratigraphy-; biozones-; Bivalvia-; carbonate-rocks; Cephalopoda-; Chipaque-Formation; classification-; Colombia-; Colombian-Basin; Cretaceous-; depositional-environment; Fomeque-Formation; Foraminifera-; Guadalupe-Formation; Guadalupe-Group; Guaduas-Formation; ichnofossils-; Invertebrata-; limestone-; lithostratigraphy-; Lower-Cretaceous; Maestrichtian-; Mesozoic-; micrite-; microfossils-; mineral-composition; Mollusca-; paleogeography-; petroleum-; petroleum-exploration; Protista-; regression-; sea-level-changes; sedimentary-basins; sedimentary-rocks; sedimentary-structures; sedimentology-; Senonian-; sequence-stratigraphy; South-America; stratigraphic-boundary; stratigraphic-units; tectonics-; Tetrabranchiata-; transgression-; traps-; Une-Formation; Upper-Cretaceous; Villeta-Group

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N030000; N060000; LONG: W0730000; W0770000.

IL - ILLUSTRATION: Refs: 65; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2004-043421

UD - UPDATE CODE: 200412

Registro 104 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: A proposal on the classification of systems tracts; application to the allostratigraphy and sequence stratigraphy of the Cretaceous Colombian Basin; Part 1, Berriasian to Hauterivian.

AU - AUTHORS: Guerrero-Javier

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Grupo de Investigaciones en Estratigrafia, Sedimentologia y Paleontologia, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 27; Pages 3-25. 2002.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 2002.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 2002

LA - LANGUAGE: English

LS - LANGUAGE OF SUMMARY: Spanish

AB - ABSTRACT: The systems tracts produced during relative sea level change cycles are subdivided in four instead of the three originally proposed by Exxon researchers. The new systems tract is named here Regressive Systems Tract (RST) and results from recognizing strata deposited in an interval of time during which relative sea level is falling. Because of these, the strata deposited during a sea level cycle are composed of progradational (RST), low aggradational, (LST), retrogradational (TST), and high aggradational (HST). The sequence boundary (SB) is placed at the base of the RST, at the horizon (Regressive Surface, RS) where relatively fast sea level fall is initiated. The base of the Lowstand Systems Tract is the Lowstand Surface (LS) reached at lowest sea level after a prolonged interval of sea level fall, and after which sea level stays low during a given interval of time. The base of the TST continues to be the Transgressive Surface (TS), as well as the base of the HST continues to be the Maximum Flooding Surface (MFS). This subdivision of systems tracts in distinct packages of strata with more precise boundaries has been applied to the Cretaceous succession from Colombia. The systems tracts are used not only to subdivide sequences, but also to separate allostratigraphic units that can be identified in the whole basin, by identifying notorious boundaries and different patterns of sedimentation of strata above and below. The allostratigraphic units in which the predominantly marine succession of the Cretaceous Colombian Basin has been subdivided include the Caqueza, Villeta, and Guadalupe Allogroups. The Tithonian/Berriasian to Hauterivian Caqueza Allogroup is subdivided into the Buenavista, Macanal, and Alto de Caqueza Alloformations. The Barremian to Santonian Villeta Allogroup is composed of the Fomeque, Une, and Chipaque Alloformations. The Campanian and Early Maastrichtian Guadalupe Allogroup is subdivided into the Lower, Middle, and Upper Guadalupe Alloformations. These are finally capped by the Late Maastrichtian lower part of the Guaduas Alloformation. Each allostratigraphic unit is composed of several lithostratigraphic units laterally adjacent and essentially synchronous, but with different types of lithology, due to lateral facies changes within a given time interval. These lithostratigraphic units deposited during evolution of the Cretaceous Colombian Basin, including valid and formally named members, formations, and groups, are discussed and compared so that a framework of correlation and exploration can be established.

DE - DESCRIPTORS: allostratigraphy-; Alto-de-Caqueza-Formation; Ammonoidea-; Andes-; assemblages-; back-arc-basins; basins-; Berriasian-; biostratigraphy-; biozones-; Bivalvia-; Buenavista-Formation; Caqueza-Group; Cephalopoda-; Chipaque-Formation; classification-; Colombia-; Colombian-Basin; Cretaceous-; depositional-environment; Fomeque-Formation; Foraminifera-; Guadalupe-Formation; Guadalupe-Group; Guaduas-Formation; Hauterivian-; Invertebrata-; lithostratigraphy-; Lower-Cretaceous; Macanal-Formation; Mesozoic-; microfossils-; Mollusca-; paleoenvironment-; paleogeography-; petroleum-; petroleum-exploration; progradation-; Protista-; retrogradation-; sea-level-changes; sedimentary-basins; sedimentary-rocks; sedimentation-; sedimentology-; sequence-stratigraphy; South-America; stratigraphic-units; tectonics-; Tetrabranchiata-; unconformities-; Une-Formation; Villeta-Group

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N030000; N060000; LONG: W0730000; W0770000.

IL - ILLUSTRATION: Refs: 50; illus. incl. sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute.

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2004-043420

UD - UPDATE CODE: 200412

Registro 105 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Pollen representation and successional vegetation change on the sandstone plateau of Araracuara, Colombian Amazonia.

AU - AUTHORS: Berrio-Juan-C; Arbelaez-Maria-V; Duivenvoorden-Joost-F; Cleef-Antoine-M; Hooghiemstra-Henry

AF - AUTHOR AFFILIATION: Universiteit van Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Amsterdam, Netherlands

SO - SOURCE: Review of Palaeobotany and Palynology. 126; 3-4, Pages 163-181. 2003.

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

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: The floral composition of the vegetation on the sandstone plateaus near Araracuara (Colombian Amazonas) was studied on the basis of 92 vegetation relevees. We compared the vegetation data with samples of the modern pollen rain in the 18 relevees that had non-barren pollen samples. By using the association index of Davis [Rev. Palaeobot. Palynol. 40 (1984) 295-315] and correspondence analysis, we evaluated to which degree pollen spectra reflect the actual vegetation. Rain forest taxa appeared overrepresented in the pollen rain on the sandstone plateau. Poaceae, Xyris, Cyperaceae, and Melastomataceae showed highest correspondence between pollen rain and measured vegetation cover, whereas Bonnetia, Bromeliaceae, and Ochnaceae showed an intermediate level of accuracy. Pollen analysis of a 25-cm sediment core, reflecting vegetation changes on the Araracuara sandstone plateau during the latest Holocene cm, showed a transition from open Rapateaceae-dominated vegetation to a Bonnetia martiana-dominated scrub. Successional stages in the pollen record were interpreted as discrete vegetation communities in the field, all occurring at present day as part of a mosaic-like vegetation. The pollen record included a substantial number of genera and families in which C (sub 4) and CAM physiological pathways are common.

DE - DESCRIPTORS: Amazonas-Colombia; Araracuara-Plateau; Cenozoic-; Colombia-; cores-; correspondence-analysis; floral-list; Holocene-; microfossils-; miospores-; modern-analogs; paleoenvironment-; palynomorphs-; plateaus-; pollen-; quantitative-analysis; Quaternary-; sediments-; South-America; statistical-analysis; succession-; upper-Holocene; vegetation-

CC - CATEGORY CODES: 24-Quaternary-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: S010000; S000000; LONG: W0720000; W0730000.

IL - ILLUSTRATION: Refs: 57; illus. incl. 2 tables, geol. sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

IS - ISSN: 0034-6667

CO - CODEN: RPPYAX

AN - ACCESSION NUMBER: 2004-042941

UD - UPDATE CODE: 200412

Registro 106 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Rb-Sr and Sm-Nd isotopic study of the Puqui Complex, Colombian Andes.

AU - AUTHORS: Ordonez-Carmona-Oswaldo; Pimentel-Marcio-M

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Recursos Minerales, Medellin, Colombia

SO - SOURCE: Journal of South American Earth Sciences. 15; 2, Pages 173-182. 2002.

PB - PUBLISHER: Pergamon. Oxford, United Kingdom. 2002.

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 2002

LA - LANGUAGE: English

LS - LANGUAGE OF SUMMARY: Spanish

AB - ABSTRACT: The Puqui Complex is exposed in the northwestern part of the Colombian Central Cordillera and consists of a complex association of metamorphic rocks (amphibolite facies gneisses, migmatites, granulites, and amphibolites) intruded by the Puqui Tonalite, a large and mostly undeformed intrusion. The Puqui Tonalite is calc-alkaline and displays a mild peraluminous character, whereas the gneissic country rocks are strongly peraluminous (and interpreted as derived from a sedimentary protolith). A peculiar feature of this tonalitic body is the common presence of garnet (up to 7% modal proportion in some localities). The Rb-Sr data for the Puqui Gneiss yielded an isochron age of 306+ or -11 Ma with a high initial (super 87) Sr/ (super 86) Sr ratio (ca. 0.70980). This is interpreted as the result of Late Paleozoic metamorphic resetting of the Rb-Sr isotopic system of the sedimentary/metasedimentary protolith. This metamorphic event is also recognized in other parts of the Colombian Andes. Sm-Nd garnet-whole rock ages, however, indicate that these rocks have also been involved in a much younger metamorphic event, between ca. 140 and 120 Ma. Sm-Nd model ages reveal a Precambrian age for the source of the original sediments (T (sub DM) model ages are in the range 1.33-1.53 Ga). The Puqui Tonalite was emplaced at ca. 248+ or -17 Ma (whole-rock Rb-Sr isochron) with an initial (super 87) Sr/ (super 86) Sr ratio of ca. 0.70748, which suggests some contribution from older sialic material in the original magma. This is confirmed by the Sm-Nd isotopic data, which show epsilon (sub Nd(248)) between -5 and -6.15 and T (sub DM) model ages between 1.17 and 2.13 Ga. These results suggest that the original tonalitic magma is strongly contaminated by the Puqui Gneiss. These preliminary Nd-Sr isotopic data suggest the presence of Precambrian crustal material in this part of the Colombian Central Cordillera. We also postulate that the Puqui Gneisses derived from Precambrian peraluminous crustal sources served as the contaminant of the tonalitic magma.

DE - DESCRIPTORS: absolute-age; Andes-; Central-Cordillera; chemical-composition; Colombia-; dates-; garnet-group; gneisses-; metamorphic-core-complexes; metamorphic-rocks; nesosilicates-; orogenic-belts; orthosilicates-; Paleozoic-; Puqui-Complex; Rb-Sr; silicates-; Sm-Nd; South-America; tectonics-; upper-Paleozoic; whole-rock

CC - CATEGORY CODES: 03-Geochronology; 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 26; illus. incl. 5 tables, sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

IS - ISSN: 0895-9811

AN - ACCESSION NUMBER: 2004-042527

UD - UPDATE CODE: 200412

Registro 107 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Wide plate margin deformation, southern Central America and northwestern South America, CASA GPS observations.

AU - AUTHORS: Trenkamp-Robert; Kellogg-James-N; Freymueller-Jeffrey-T; Mora-Hector-P

AF - AUTHOR AFFILIATION: University of South Carolina, Department of Geological Sciences, Columbia, SC, United States

SO - SOURCE: Journal of South American Earth Sciences. 15; 2, Pages 157-171. 2002.

PB - PUBLISHER: Pergamon. Oxford, United Kingdom. 2002.

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 2002

LA - LANGUAGE: English

AB - ABSTRACT: Global positioning system data from southern Central America and northwestern South America were collected during 1991, 1994, 1996, and 1998 in Costa Rica, Panama, Ecuador, Colombia, and Venezuela. These data reveal wide plate boundary deformation and escape tectonics occurring along an approximately 1400 km length of the North Andes, locking of the subducting Nazca plate and strain accumulation in the Ecuador-Colombia forearc, ongoing collision of the Panama arc and Colombia, and convergence of the Caribbean plate with Panama and South America. Elastic modeling of observed horizontal displacements in the Ecuador forearc is consistent with partial locking (50%) in the subduction zone and partial transfer of motion to the overriding South American plate. The deformation is hypothesized to reflect elastic recoverable strain accumulation associated with the historic seismicity of the area and active faulting associated with permanent shortening of 6 mm/a. Deformation associated with the Panama-Colombia collision is consistent with elastic strain accumulation on a fully locked Atrato-Uraba Fault Zone suture.

DE - DESCRIPTORS: Andes-; Caribbean-region; Central-America; Colombia-; continental-crust; Costa-Rica; crust-; deformation-; earthquakes-; Ecuador-; Global-Positioning-System; Northern-Andes; oblique-orientation; Panama-; plate-boundaries; plate-collision; plate-tectonics; remote-sensing; satellite-methods; South-America; subduction-; Venezuela-

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 96; illus. incl. 2 tables, sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

IS - ISSN: 0895-9811

AN - ACCESSION NUMBER: 2004-042526

UD - UPDATE CODE: 200412

Registro 108 de 5614 - GeoRef : 2002-2004/12

BK - BOOK TITLE: Geometry and kinematics of the central Middle Magdalena Basin, Colombia.

BA - BOOK AUTHORS: Aristizabal-John-Jairo

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 2002

DG - DEGREE GRANTED: Master's

DI - DEGREE GRANTING INSTITUTION: Colorado State University. Fort Collins, CO, United States. Pages: 108. 2002.

LA - LANGUAGE: English

AB - ABSTRACT: The complex evolution of the Middle Magdalena Basin, located between the Central and Eastern Cordilleras of Colombia, includes extension during the early Jurassic and two major contractile events during the Cenozoic. The basin was developed into a foreland basin in the Late Cretaceous-Early Tertiary and evolved into a regional piggy-back basin in the Middle Tertiary. This evolution resulted in a variety of structural styles that varied through time and space. Such variety cannot be explained in a single restorable cross-section or a single fault-related fold model. To document the structural styles in the Middle Magdalena Basin, five structural cross-sections were constructed and restored at two stages in order to study the structural configuration prior to the two major contractile events. 152 wells, 1200 km of seismic reflection profiles, and surface data were used to construct the structural cross-sections. These sections were balanced in 2D and combined into a 3D model. Section restorations in combination with the 3D model reveal the presence of two opposite-directed triangle zones. In the western margin of the basin, an Early Tertiary eastward-directed triangle zone in Cretaceous sediments was followed by a Late Oligocene westward-directed triangle zone in the east. Data suggest that both triangle zones were truncated by out-of-sequence, high-angle faulting in the Late Miocene. Current data suggest that the Middle Magdalena Basin and Eastern Cordillera belong to a major dextral transpressive system. The system appears to be bordered by the Guaicaramo and Palestina faults, where strain is probably partitioned into dextral strike slip and strike-perpendicular shortening. Many structures in the Middle Magdalena Basin are probably backlimb tightening expressions of the Guaicaramo Fault, the master fault responsible for the uplift of the Eastern Cordillera. Both oblique movements and backlimb tightening can explain the presence of high-angle faults in the area. The results of this research include a better characterization of the structural styles of the central Middle Magdalena basin, the timing of those styles, the genesis of low- and high-angle faults, an alternative interpretation of the Middle Magdalena Basin and Eastern Cordillera as a dextral transpressive system, and a new hypothesis for structures in the western foothills of the Eastern Cordillera as backlimb-tightening structures. From the oil exploration perspective, these results suggest a suite of different exploration opportunities related to duplexes, subthrust areas, and stratigraphic plays.

DE - DESCRIPTORS: Andes-; basins-; Cenozoic-; Central-Cordillera; Colombia-; Eastern-Cordillera; faults-; folds-; foreland-basins; geometry-; geophysical-methods; geophysical-profiles; geophysical-surveys; Guaicaramo-Fault; kinematics-; Mesozoic-; Middle-Magdalena-Basin; petroleum-; petroleum-exploration; seismic-methods; seismic-profiles; South-America; strain-; surveys-; tectonics-; Tertiary-; three-dimensional-models; transpression-; triangle-zones

CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources; 16-Structural-geology; 20-Applied-geophysics

DT - DOCUMENT TYPE: Thesis-or-Dissertation

BL - BIB LEVEL: Monograph

IL - ILLUSTRATION: Refs: 134

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute.

AN - ACCESSION NUMBER: 2004-042006

UD - UPDATE CODE: 200412

Registro 109 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: A new Karsteniceras from the Barremian (Lower Cretaceous) of Columbia.

AU - AUTHORS: Vasicek-Zdenek; Hoedemaeker-Philip-J

AF - AUTHOR AFFILIATION: VSB-Technical University of Ostrava, Ostrava-Poruba, Czech Republic

SO - SOURCE: Scripta Geologica. 125; Pages 141-143. 2003.

PB - PUBLISHER: Rijksmuseum van Geologie en Mineralogie. Leiden, Netherlands. 2003.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

DE - DESCRIPTORS: Ammonoidea-; Barremian-; Boachianitidae-; Cephalopoda-; Colombia-; Cretaceous-; Invertebrata-; Karsteniceras-aequicostatum; Lower-Cretaceous; Mesozoic-; Mollusca-; morphology-; new-taxa; South-America; taxonomy-; Tetrabranchiata-; Villa-de-Leyva-Colombia

CC - CATEGORY CODES: 10-Invertebrate-paleontology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 12; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute.

IS - ISSN: 0375-7587

CO - CODEN: SCGLA5

AN - ACCESSION NUMBER: 2004-041902

UD - UPDATE CODE: 200412

Registro 110 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Crustal-scale cross-section of the U. S. Cordillera, California and beyond, its tectonic significance, and speculations on the Andean Orogeny.

AU - AUTHORS: Moores-E-M; Wakabayashi-J; Unruh-J-R

AF - AUTHOR AFFILIATION: University of California at Davis, Department of Geology, Davis, CA, United States

BK - BOOK TITLE: In: The lithosphere of western North America and its geophysical characterization.

BA - BOOK AUTHORS: Klemperer-Simon-L (editor); Ernst-W-Gary (editor)

SO - SOURCE: International Book Series. 7; Pages 191-212. 2003.

PB - PUBLISHER: Bellwether Publishing for the Geological Society of America. Columbia, MD, United States. 2003.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 2003

CN - CONFERENCE INFORMATION: The lithosphere of western North America and its geophysical characterization. Stanford, CA, United States. Dec. 8-9, 2001.

LA - LANGUAGE: English

AB - ABSTRACT: A cross-section across northern California from the San Andreas fault to central Nevada exhibits both major east- and west-vergent structures. East-vergent structures include crustal wedging and fault-propagation folds in the Coast Ranges, emplacement of the Great Valley ophiolitic basement over Sierran basement rocks, early east-vergent structures in the latter, displacement along the eastern margin of the Sierra Nevada batholith, and thrust faults in western Nevada. West-vergent structures include faults within the Franciscan complex and "retrocharriage" structures in the Sierra Nevada. A model of evolution of the U.S. Pacific margin emphasizes the role of ophiolites, island arc-continental margin collisions, and subduction of a large oceanic plateau. Early Mesozoic subduction along the Pacific margin of North America was modified by a 165-176 Ma collision of a major intra-oceanic arc/ophiolite complex. A complex SW Pacific-like set of small plates and their boundaries at various times may have been present in southern California between 115 and 40 Ma. Subduction of an oceanic plateau about 85-65 Ma (remnants in the Franciscan) produced east-vergent tectonic wedging in the Coast Ranges, possible thrusting along the eastern Sierra Nevada batholith margin, and development of rocky Mountain Laramide structures. The "Laramide orogeny" is herein redefined to include all late Cretaceous-Early Tertiary (75-45 Ma) fold-thrust structures from the Pacific Coast to the Rocky Mountains. A speculative model for collisional involvement in the Andean orogeny is also presented, based upon timing of the onset of the Andean orogeny, the presence of oceanic terranes along the western margin of the Andes, and the presence along part of the length of the chain of a remnant marginal basin.