No. Registros Solicitud 1 5614 colombia



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SO - SOURCE: Special Paper - Geological Society of America. 332; Pages 191-202. 1999.

PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 1999.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: carbonate-platforms; carbonate-rocks; chemically-precipitated-rocks; chert-; clastic-rocks; Colombia-; continental-margin; Cretaceous-; hemipelagic-environment; La-Frontera-Formation; limestone-; lithofacies-; Magdalena-Valley; marine-environment; Mesozoic-; northern-South-America; paleo-oceanography; paleobiology-; passive-margins; petroleum-; plate-tectonics; productivity-; red-beds; sea-level-changes; sedimentary-rocks; shale-; source-rocks; South-America; South-American-Plate; upwelling-; Venezuela-; Villeta-Group

CC - CATEGORY CODES: 12-Stratigraphy; 18-Solid-earth-geophysics

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 35; illus. incl. sect., strat. cols., sketch maps.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.

IS - ISSN: 0072-1077

IB - ISBN: 0-8137-2332-9

CO - CODEN: GSAPAZ

AN - ACCESSION NUMBER: 1999-061562

UD - UPDATE CODE: 199921

Registro 5333 de 5614 - GeoRef 1997-2001

TI - TITLE: Dual dynamic programing; a note on implementation.

AU - AUTHORS: Velasquez-Jesus; Restrepo-Pedro-J; Campo-Rafael

AF - AUTHOR AFFILIATION: DecisionWare, Bogota, Colombia

SO - SOURCE: Water Resources Research. 35; 7, Pages 2269-2271. 1999.

PB - PUBLISHER: American Geophysical Union. Washington, DC, United States. 1999.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: algorithms-; critical-review; dual-dynamic-programing; equations-; hydrology-; reservoirs-; surface-water

CC - CATEGORY CODES: 21-Hydrogeology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 6

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.

IS - ISSN: 0043-1397

CO - CODEN: WRERAQ

AN - ACCESSION NUMBER: 1999-059143

UD - UPDATE CODE: 199920

Registro 5334 de 5614 - GeoRef 1997-2001

TI - TITLE: The complex frequencies of long-period seismic events as probes of fluid composition beneath volcanoes.

AU - AUTHORS: Kumagai-Hiroyuki; Chouet-Bernard-A

AF - AUTHOR AFFILIATION: U. S. Geological Survey, Menlo Park, CA, United States

SO - SOURCE: Geophysical Journal International. 138; 2, Pages F7-F12. 1999.

PB - PUBLISHER: Blackwell Scientific. Oxford, United Kingdom. 1999.

RP - RESEARCH PROGRAM: USGSOP (Non-USGS publications with USGS authors)

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: Alaska-; Andes-; anelasticity-; Asia-; basalts-; carbon-dioxide; chemical-composition; Colombia-; cracks-; earthquake-prediction; East-Pacific-Ocean-Islands; Far-East; fluid-phase; frequency-; Galeras-; gaseous-phase; Hawaii-; Hawaii-County-Hawaii; Hawaii-Island; igneous-rocks; Japan-; Kilauea-; Kusatsu-Shirane; magma-chambers; magmas-; models-; Oceania-; Polynesia-; precursors-; Q-; Redoubt-; seismicity-; seismograms-; Sompi-method; South-America; Southern-Alaska; time-factor; United-States; volcanic-rocks; volcanoes-; waveforms-

CC - CATEGORY CODES: 19-Seismology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 21; illus.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.

IS - ISSN: 0956-540X

AN - ACCESSION NUMBER: 1999-057766

UD - UPDATE CODE: 199919

Registro 5335 de 5614 - GeoRef 1997-2001

TI - TITLE: Application of new diterpane biomarkers to source, biodegradation and mixing effects on central Llanos Basin oils, Colombia.

AU - AUTHORS: Dzou-Leon-I; Holba-Albert-G; Ramon-Juan-C; Moldowan-J-Michael; Zinniker-David

AF - AUTHOR AFFILIATION: ARCO Exploration and Production Technology, Plano, TX, United States

SO - SOURCE: Organic Geochemistry. 30; 7, Pages 515-534. 1999.

PB - PUBLISHER: Pergamon. Oxford-New York, International. 1999.

CP - COUNTRY OF PUBLICATION: International

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: aliphatic-hydrocarbons; alkanes-; aromatic-hydrocarbons; asphalt-; biodegradation-; biomarkers-; bitumens-; C-13-C-12; carbon-; Cenozoic-; Colombia-; Cretaceous-; diterpanes-; effects-; Eocene-; gas-chromatograms; hydrocarbons-; isotope-ratios; isotopes-; La-Luna-Formation; Llanos-; mass-spectra; Mesozoic-; Mirador-Formation; mixing-; norhopanes-; oleananes-; organic-compounds; Paleogene-; petroleum-; phytane-; pristane-; saturated-hydrocarbons; source-rocks; South-America; spectra-; stable-isotopes; sulfur-; Tertiary-; triterpanes-; Upper-Cretaceous

CC - CATEGORY CODES: 29A-Economic-geology,-geology-of-energy-sources; 02D-Isotope-geochemistry

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 27; illus. incl. strat. col., 2 tables, sketch maps.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.

IS - ISSN: 0146-6380

AN - ACCESSION NUMBER: 1999-055406

UD - UPDATE CODE: 199919

Registro 5336 de 5614 - GeoRef 1997-2001

TI - TITLE: Tectonic architecture of the Subandean fold and thrust belt; structural style variations and occurrence of hydrocarbon traps.

AU - AUTHORS: Dengo-Carlos-A

AF - AUTHOR AFFILIATION: Exxon Exploration Company, Houston, TX, United States

SO - SOURCE: Bulletin of the South Texas Geological Society. 39; 5, Pages 7. 1999.

PB - PUBLISHER: South Texas Geological Society. San Antonio, TX, United States. 1999.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: accretion-; Andes-; basement-tectonics; Cenozoic-; chemically-precipitated-rocks; Colombia-; compression-tectonics; decollement-; deformation-; evaporites-; faults-; fold-and-thrust-belts; genesis-; maturity-; Miocene-; Neogene-; petroleum-; petroleum-accumulation; Quaternary-; reactivation-; reverse-faults; sedimentary-rocks; segmentation-; source-rocks; South-America; structural-traps; subduction-; tectonics-; Tertiary-; thin-skinned-tectonics; transpression-; traps-; uplifts-; Venezuela-

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

DT - DOCUMENT TYPE: Abstract; Serial

BL - BIB LEVEL: Analytic

NN - ANNOTATION: Presented at the South Tex. Geol. Soc. Jan. meeting, San Antonio, TX, Jan. 13, 1999.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.

IS - ISSN: 0561-077X

CO - CODEN: BSTGAE

AN - ACCESSION NUMBER: 1999-054686

UD - UPDATE CODE: 199919

Registro 5337 de 5614 - GeoRef 1997-2001

TI - TITLE: Oceanic plateau and island arcs of southwestern Ecuador; their place in the geodynamic evolution of northwestern South America.

AU - AUTHORS: Reynaud-Cedric; Jaillard-Etienne; Lapierre-Henriette; Mamberti-Marc; Mascle-Georges-H

AF - AUTHOR AFFILIATION: Universite Joseph Fourier, Institut Dolomieu, Grenoble, France

SO - SOURCE: Tectonophysics. 307; 3-4, Pages 235-254. 1999.

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1999.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

AB - ABSTRACT: Coastal Ecuador is made up of an oceanic igneous basement overlain by Upper Cretaceous to Lower Paleocene ( nearly equal 98-60 Ma) volcaniclastic and volcanic rocks of island-arc affinities. The igneous basement, known as the Pinon Formation, locally dated at 123 Ma, consists of olivine-free basalts and dolerites. Relative to N-MORB, both types of rocks exhibit high concentrations in Nb (0.3-10.75 ppm), Ta (0.03-0.67 ppm), Th (0.11-1.44 ppm), light and medium rare earth elements, and low Zr (22-105 ppm) and Hf (0.59-2.8 ppm) contents, thus showing oceanic plateau basalts affinities. Most of these oceanic plateau basalts tholeiites display rather homogeneous epsilon (sub Nd(T = 123 Ma)) ratios ( approximately +7), with the exception of two rocks with higher (+10) and lower (+4.5) epsilon (sub Nd(T = 123 Ma)) , respectively. All these basalts plot, with one exception, within the ocean island basalts field. Their ( (super 87) Sr/ (super 86) Sr) (sub i) ratios are highly variable (0.7032-0.7048), probably due to hydrothermal oceanic alteration or assimilation of altered oceanic crust. The rocks of the Pinon Formation are geochemically similar to the oceanic plateau tholeiites from Nauru and Ontong Java Plateaus and to the Upper Cretaceous (92-88 Ma) Caribbean Oceanic Plateau lavas. The basalts and dolerites of the Upper Cretaceous-Lower Paleocene island arcs show calc-alkaline affinities. The epsilon (sub Nd) ratios (+6.1 to +7.1) of these arc-rocks are very homogenous and fall within the range of intra-oceanic island-arc lavas. The Upper Cretaceous-Lower Paleocene calc-alkaline and tholeiitic rocks from coastal Ecuador share similar high epsilon (sub Nd) ratios to Cretaceous intra-oceanic arc rocks from north, central and South America and from the Greater Antilles. Since the Pinon oceanic plateau tholeiites are locally overlain by early-Late Cretaceous sediments ( approximately 98-83 Ma) and yielded locally an Early Cretaceous age, they do not belong to the Late Cretaceous Caribbean Oceanic Plateau. The basement of coastal Ecuador is interpreted as an accreted fragment of an overthickened and buoyant oceanic plateau. The different tectonic units of coastal Ecuador cannot be easily correlated with those of western Colombia, excepted the Late Cretaceous San Lorenzo and Ricaurte island arcs. It is suggested that northwestern South America consists of longitudinally discontinuous terranes, built by repeated accretionary events and significant longitudinal displacement of these terranes.

DE - DESCRIPTORS: accretion-; alkaline-earth-metals; basalts-; basement-; calc-alkalic-composition; Cenozoic-; chemical-composition; coastal-environment; concentration-; Cretaceous-; crust-; diabase-; Ecuador-; geochemistry-; geodynamics-; hydrothermal-alteration; igneous-rocks; island-arcs; isotope-ratios; isotopes-; lithogeochemistry-; lower-Paleocene; Mesozoic-; metals-; metasomatism-; mid-ocean-ridge-basalts; Nd-144-Nd-143; neodymium-; oceanic-crust; Paleocene-; Paleogene-; Pinon-Formation; plate-tectonics; plutonic-rocks; rare-earths; South-America; southwestern-Ecuador; Sr-87-Sr-86; stable-isotopes; strontium-; terranes-; Tertiary-; tholeiitic-basalt; trace-elements; Upper-Cretaceous; volcanic-rocks

CC - CATEGORY CODES: 02C-Geochemistry-of-rocks,-soils,-and-sediments; 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: S020000; S000000; LONG: W0800000; W0810000.

IL - ILLUSTRATION: Refs: 77; illus. incl. 3 tables, geol. sketch maps.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

IS - ISSN: 0040-1951

CO - CODEN: TCTOAM

AN - ACCESSION NUMBER: 1999-049887

UD - UPDATE CODE: 199917

Registro 5338 de 5614 - GeoRef 1997-2001

TI - TITLE: Emeralds in the Eastern Cordillera of Colombia; two tectonic settings for one mineralization.

AU - AUTHORS: Branquet-Yannick; Laumonier-Bernard; Cheilletz-Alain; Giuliani-Gaston

AF - AUTHOR AFFILIATION: Centre National de la Recherche Scientifique, Centre de Recherches Petrographiques et Geochimiques, Vandoeuvre-Les-Nancy, France

SO - SOURCE: Geology (Boulder). 27; 7, Pages 597-600. 1999.

PB - PUBLISHER: Geological Society of America (GSA). Boulder, CO, United States. 1999.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

AB - ABSTRACT: Colombian emeralds are formed through a hydrothermal-sedimentary process. On the western side of the Eastern Cordillera, the deposits are linked by tear faults and associated thrusts developed during a compressive tectonic phase that occurred at the time of the Eocene-Oligocene boundary, prior to the major uplift of the Cordillera during the Andean phase (middle Miocene). On the eastern side of the Cordillera, emerald mineralization occurred earlier, at the time of the Cretaceous-Tertiary boundary, during a thin-skinned extensional tectonic event linked to evaporite dissolution. This event predates the Andean phase, during which this part of the chain was folded and thrust over the Llanos foreland.

DE - DESCRIPTORS: Andes-; Cenozoic-; Colombia-; compression-tectonics; Eastern-Cordillera; emerald-; Eocene-; extension-tectonics; faults-; folds-; gems-; Llanos-; lower-Oligocene; mineral-deposits,-genesis; mineralization-; Oligocene-; Paleogene-; ring-silicates; silicates-; solution-; South-America; structural-controls; tear-faults; tectonics-; Tertiary-; thin-skinned-tectonics; thrust-faults; uplifts-; upper-Eocene

CC - CATEGORY CODES: 28A-Economic-geology,-geology-of-nonmetal-deposits; 16-Structural-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 13; sects., strat. cols., sketch maps.

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: 0091-7613

CO - CODEN: GLGYBA

AN - ACCESSION NUMBER: 1999-049823

UD - UPDATE CODE: 199917

Registro 5339 de 5614 - GeoRef 1997-2001

TI - TITLE: Robert Lee Sprinkel, Jr. (1907-1998).

AU - AUTHORS: Beaumont-Kay-Sprinkel

SO - SOURCE: AAPG Bulletin. 83; 6, Pages 1026. 1999.

PB - PUBLISHER: American Association of Petroleum Geologists. Tulsa, OK, United States. 1999.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1999



LA - LANGUAGE: English

AB - ABSTRACT: Robert Lee Sprinkel, Jr., a longtime member of AAPG and a distinguished minerals and petroleum engineer and geologist, died April 3, 1998 in Denver, Colorado at the age of 90. He was born on October 11, 1907, in Kinta, Indian Territory (Oklahoma), was schooled in Muskogee, Oklahoma through high school, and graduated from the University of California at Berkeley in 1930 with a degree in mining engineering. He was commissioned in the U.S. Army Reserve in 1929, rising to the rank of lieutenant colonel before his retirement in 1972. After graduation from the University of California, Bob went to work for his former Berkeley professor, Andrew Lawson, doing the geological soundings for the San Francisco-Oakland Bay Bridge. In 1987, on the occasion of the 50th anniversary of the Bay Bridge, Bob was honored as a Bay Bridge Pioneer. Following his work on the Bay Bridge, Bob worked as a hydrologist with C&H Sugar Refinery in Crockett, California. In 1932, Bob married Marian Boyles, a classmate from Berkeley. The following year the newlyweds went to the Philippines, where Bob worked as a mining engineer with the Big Wedge Mining Company in Baguio. Their first child, Robert Lee Sprinkel III, was born in Baguio on April 13, 1935. Returning to the United States in late 1935, Bob worked for the city of San Francisco on a water-table project at Fleischhacker Zoo. He joined Shell Oil Company as a geologist in Los Angeles in 1938, the year their daughter, Kay Marianne, was born on June 19. Bob was with Shell Oil until 1952, except for his time on active duty during World War II. Bob left for active duty in 1942 and was deployed to England, France, and Belgium. He was part of Operation Overlord, the D-Day invasion of France in June 1944. During the war, he commanded an ordnance battalion, achieving the rank of captain. He was separated from active duty in March 1946, and returned to Sacramento. Afterward, Shell moved him to Ventura and then to Long Beach. In 1952, he joined the Northern Pacific Railway in their oil development department in Billings, Montana, working in the Williston Basin oil fields. He joined Seaboard Oil in 1955, remaining in Billings until 1956, when he moved to Denver with Texaco. From 1962 to 1965, Bob and Marian lived in Bogota, Colombia, where he was chief geologist for Colombia and northern Ecuador for Texaco. They returned to Denver, and Bob continued to work with Texaco until his retirement in 1973. Retirement was too confining for Bob, and in 1974 he began 20 years of consulting in the energy industry, including work with his son in England in the minerals business. He worked with Pace and Cameron Engineers in Denver, and often served as an expert witness in minerals- related legal matters. In 1993, Bob and daughter Kay made a memorable pilgrimage to Normandy, where he revisited the memories and beaches of the 1944 landing at Omaha Beach. The following year he was severely injured in an automobile accident, and his health declined after that incident. Bob was a registered engineer and a member of the AAPG, Reserve Officers Association, Petroleum Pioneers, Rocky Mountain Petroleum Geologists, Colorado Mining Association, Sigma Phi Epsilon Fraternity, Society of Mining Engineers, Society of Petroleum Engineers, American Institute of Professional Geologists, and Montana Geological Association. Survivors include his wife of 65 years, Marian; his daughter, Kay Sprinkel Beaumont of San Francisco; his son, Robert III of Rutland, England; a sister, Beatrice Sprinkel of San Francisco; 11 grandchildren, and 13 great-grandchildren. Memorial contributions may be made to Yellowstone Boys and Girls Ranch, Billings, Montana, or to the AAPG scholarship fund.

DE - DESCRIPTORS: biography-; petroleum-; Sprinkel,-Robert-Lee,-Jr.

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: portr.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States

IS - ISSN: 0149-1423

CO - CODEN: AABUD2

AN - ACCESSION NUMBER: 1999-049629

UD - UPDATE CODE: 199917

Registro 5340 de 5614 - GeoRef 1997-2001

TI - TITLE: Implications of (super 187) Os isotopic heterogeneities in a mantle plume; evidence from Gorgona Island and Curacao.

AU - AUTHORS: Walker-Richard-J; Storey-Michael; Kerr-Andrew-C; Tarney-John; Arndt-Nicholas-T

AF - AUTHOR AFFILIATION: University of Maryland, Isotope Geochemistry Laboratory, College Park, MD, United States

SO - SOURCE: Geochimica et Cosmochimica Acta. 63; 5, Pages 713-728. 1999.

PB - PUBLISHER: Pergamon. Oxford, International. 1999.

CP - COUNTRY OF PUBLICATION: International

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: absolute-age; Antilles-; basalts-; Caribbean-region; Colombia-; Cretaceous-; crust-; Curacao-; dates-; East-Pacific; enrichment-; Gorgona-Island; heterogeneity-; igneous-rocks; isochrons-; isotope-ratios; isotopes-; large-igneous-provinces; lead-; Lesser-Antilles; mafic-composition; mantle-; mantle-plumes; Mesozoic-; metals-; Nd-144-Nd-143; neodymium-; Netherlands-Antilles; oceanic-crust; Os-188-Os-187; osmium-; Pacific-Ocean; Pb-206-Pb-204; platinum-group; radioactive-isotopes; rare-earths; Re-Os; South-America; stable-isotopes; tholeiitic-basalt; ultramafic-composition; Upper-Cretaceous; volcanic-rocks; volcanism-; West-Indies

CC - CATEGORY CODES: 02D-Isotope-geochemistry; 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N120800; N122800; LONG: W0684500; W0690800.

LAT: N030000; N030000; LONG: W0781500; W0781500.

IL - ILLUSTRATION: Refs: 74; illus. incl. 2 tables, geol. sketch map.

RF - REFERENCE SOURCE: GeoRef, Copyright 2002, American Geological Institute.

IS - ISSN: 0016-7037

CO - CODEN: GCACAK

AN - ACCESSION NUMBER: 1999-046861

UD - UPDATE CODE: 199916

Registro 5341 de 5614 - GeoRef 1997-2001

TI - TITLE: Tectonic segmentation of the North Andean margin; impact of the Carnegie Ridge collision.

AU - AUTHORS: Gutscher-M-A; Malavieille-J; Lallemand-S; Collot-J-Y

AF - AUTHOR AFFILIATION: Universite Montpellier II, Laboratoire de Geophysique et Tectonique, Montpellier, France

SO - SOURCE: Earth and Planetary Science Letters. 168; 3-4, Pages 255-270. 1999.

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1999.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

AB - ABSTRACT: The North Andean convergent margin is a region of intense crustal deformation, with six great subduction earthquakes M (sub w) > or =7.8 this century. The regional pattern of seismicity and volcanism shows a high degree of segmentation along strike of the Andes. Segments of steep slab subduction alternate with aseismic regions and segments of flat slab subduction. This segmentation is related to heterogeneity on the subducting Nazca Plate. In particular, the influence of the Carnegie Ridge collision is investigated. Four distinct seismotectonic regions can be distinguished: Region 1 - from 6 degrees N to 2.5 degrees N with steep ESE-dipping subduction and a narrow volcanic arc; Region 2 - from 2.5 degrees N to 1 degrees S showing an intermediate-depth seismic gap and a broad volcanic arc; Region 3 - from 1 degrees S to 2 degrees S with steep NE-dipping subduction, and a narrow volcanic arc; Region 4 - south of 2 degrees S with flat subduction and no modern volcanic arc. The Carnegie Ridge has been colliding with the margin since at least 2 Ma based on examination of the basement uplift signal along trench-parallel transects. The subducted prolongation of Carnegie Ridge may extend up to 500 km from the trench as suggested by the seismic gap and the perturbed, broad volcanic arc. These findings conflict with previous tectonic models suggesting that the Carnegie Ridge entered the trench at 1 Ma. Furthermore, the anomalous geochemical (adakitic) signature of the volcanoes in the broad Ecuador volcanic arc and the seismicity pattern are proposed to be caused by lithospheric tears separating the buoyant, shallowly subducting Carnegie Ridge from segments of steep subduction in Regions 1 and 3. It is further suggested that Carnegie Ridge supports a local "flat slab"' segment similar to that observed in Peru. The impact of the Carnegie Ridge collision on the upper plate causes transpressional deformation, extending inboard to beyond the volcanic arc with a modern level of seismicity comparable to the San Andreas fault system. The pattern of instrumental and historical seismicity indicates (1) great earthquakes on the northern and southern flanks of the colliding ridge, (2) a slight reduction in observed seismicity at the trench-ridge intersection, (3) increased stress far into the continent, and (4) a NNE displacement of the N. Andes block, to be further effects of the collision.

DE - DESCRIPTORS: Andes-; Carnegie-Ridge; classification-; Colombia-; continental-margin; crust-; earthquakes-; East-Pacific; Ecuador-; fault-planes; faults-; lithosphere-; mid-ocean-ridges; Northern-Andes; Pacific-Ocean; plate-collision; plate-convergence; plate-tectonics; segmentation-; seismicity-; seismotectonics-; slabs-; South-America; subduction-; tectonics-; transpression-


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