No. Registros Solicitud 1 5614 colombia

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011500; N011500; LONG: W0772500; W0772500.

IL - ILLUSTRATION: Refs: 47; illus. incl. 4 tables, sketch map.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 1997-052435

UD - UPDATE CODE: 199717

Registro 5604 de 5614 - GeoRef 1997-2001

TI - TITLE: Geochemistry and petrology of the Galeras volcanic complex, Colombia.

AU - AUTHORS: Calvache-V-Marta-Lucia; Williams-Stanley-N

AF - AUTHOR AFFILIATION: INGEOMINAS, Pasto, Colombia

BK - BOOK TITLE: In: Galeras Volcano, Colombia; interdisciplinary study of a Decade Volcano.

BA - BOOK AUTHORS: Stix-John (editor); Calvache-V-Marta-Lucia (editor); Williams-Stanley-N (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 77; 1-4, Pages 21-38. 1997.

NT - NOTES: Special issue

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1997.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

AB - ABSTRACT: The Galeras Volcanic Complex (GVC) has erupted lavas and pyroclastic flows, ranging from basaltic andesites to dacites, during the last million years. The chemical composition of the volcanic products has been fairly constant, characterized by calc-alkaline, high-silica, medium-potassium andesites. Variations from basaltic andesites to dacites have occurred during individual stages, but overall, composition and petrographic characteristics are quite constant. The Guaca cinder cone is the exception, being more alkaline, rather than calc-alkaline. The trace-element and REE contents of the GVC samples suggest that sediments or fluids from the subducted sediments are involved in the generation of the magmas at the source region. Although high Sr and Ba contents are also present in the upper continental crust, the high B levels are consistent with the contribution of sediment-related elements. Small degrees of partial melting of a hydrated mantle wedge are consistent with the observed distribution of REE, plus the addition of highly soluble elements from the subducted sediments. Crystal fractionation at depths of about 36 km (approximately 12 kbar) of a hydrated tholeiitic basalt melt can produce andesites and basaltic andesites having a phase assemblage of amphibole, plagioclase, clinopyroxene, magnetite, ilmenite and apatite. The magma then re-equilibrates at higher levels, reaching levels as shallow as 10 km (about 2.5 to 3 kbar) and crystallizing orthopyroxene and large amounts of plagioclase. At these shallow levels, amphibole is no longer stable and re-equilibrates to oxides, pyroxene and plagioclase. The melts become saturated with respect to most volatiles by depressurization and crystallization. In the GVC, we observe that it is not necessary to have large volumes of highly differentiated magma to cause caldera-forming eruptions.

DE - DESCRIPTORS: Andes-; calderas-; chemical-composition; Colombia-; eruptions-; Galeras-; Galeras-volcanic-complex; geochemistry-; igneous-rocks; lava-flows; melts-; pyroclastics-; South-America; volcanic-features; volcanic-rocks; volcanism-; volcanoes-

CC - CATEGORY CODES: 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011500; N011500; LONG: W0772500; W0772500.

IL - ILLUSTRATION: Refs: 46; illus. incl. 6 tables.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 1997-052434

UD - UPDATE CODE: 199717

Registro 5605 de 5614 - GeoRef 1997-2001

TI - TITLE: Stratigraphy and chronology of the Galeras volcanic complex, Colombia.

AU - AUTHORS: Calvache-V-Marta-Lucia; Cortes-Jimenez-Gloria-Patricia; Williams-Stanley-N

AF - AUTHOR AFFILIATION: INGEOMINAS, Pasto, Colombia

BK - BOOK TITLE: In: Galeras Volcano, Colombia; interdisciplinary study of a Decade Volcano.

BA - BOOK AUTHORS: Stix-John (editor); Calvache-V-Marta-Lucia (editor); Williams-Stanley-N (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 77; 1-4, Pages 5-19. 1997.

NT - NOTES: Special issue

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1997.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

AB - ABSTRACT: An understanding of the evolution of the Galeras volcanic complex (GVC) is critical for assessing and refining hazards and eruption forecasting for the current reactivation of Galeras volcano. Detailed field geology and dating by (super 14) C and (super 40) Ar- (super 39) Ar methods help establish a comprehensive stratigraphic framework, defining six different stages in the evolution of the Galeras volcanic complex. The two oldest stages, Cariaco and Pamba, represent the westernmost activity of the complex. The next stage, Coba Negra, had a caldera-forming eruption that occurred about 560 ka ago. The Coba Negra edifice, which was partially destroyed by this eruption, had a total volume of about 70 km (super 3) . The volume of pyroclastic flow deposits related to caldera formation is about 16 km (super 3) . The caldera, which has been partially destroyed, was about 5 km in diameter. The next constructional stage, Jenoy, had an edifice volume of about 64 km (super 3) . The caldera-forming event that ended this stage took place sometime between 150 and 40 ka ago. Deposits from these eruptions are found in the northeastern and southeastern slopes of the complex and have a volume of approximately 2 km (super 3) . The center of the Jenoy caldera was located east-southeast from the center of the previous Coba Negra caldera, probably along the rim of the former caldera. The diameter of the Jenoy caldera was about 4 km. A summit collapse, probably not eruption-related, occurred between 12 and 5 ka ago, during the Urcunina stage. Hydrothermally altered rocks which are found in the scar of the collapse suggest that it may have been related to instabilities created by the circulation of hydrothermal fluids in addition to a very steep slope in the western part of the edifice. The approximately 4 km (super 3) missing from the top of the volcano agrees very well with approximately 3 km (super 3) of avalanche deposits found near the town of Consaca 12 km west of the present-day summit. The system at the GVC has produced large, hazardous eruptions, although in the most recent years (less than 5 ka) the eruptions have been of small scale.

DE - DESCRIPTORS: absolute-age; age-; Andes-; Ar-Ar; argon-; C-14; calderas-; carbon-; Cenozoic-; Colombia-; dates-; eruptions-; Galeras-; Holocene-; interpretation-; isotope-ratios; isotopes-; noble-gases; Quaternary-; radioactive-isotopes; South-America; stable-isotopes; volcanic-features; volcanism-; volcanoes-

CC - CATEGORY CODES: 24-Quaternary-geology; 03-Geochronology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011500; N011500; LONG: W0772500; W0772500.

IL - ILLUSTRATION: Refs: 37; illus. incl. 1 table, sketch maps.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 1997-052433

UD - UPDATE CODE: 199717

Registro 5606 de 5614 - GeoRef 1997-2001

TI - TITLE: Galeras Volcano, Colombia; interdisciplinary study of a Decade Volcano; preface.

AU - AUTHORS: Stix-John; Calvache-V-Marta-Lucia; Williams-Stanley-N

AF - AUTHOR AFFILIATION: Universite de Montreal, Montreal, PQ, Canada

BK - BOOK TITLE: In: Galeras Volcano, Colombia; interdisciplinary study of a Decade Volcano.

BA - BOOK AUTHORS: Stix-John (editor); Calvache-V-Marta-Lucia (editor); Williams-Stanley-N (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 77; 1-4, Pages 1-4. 1997.

NT - NOTES: Special issue

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1997.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

DE - DESCRIPTORS: Andes-; Colombia-; earthquakes-; Galeras-; geochemistry-; South-America; volcanic-earthquakes; volcanism-; volcanoes-

CC - CATEGORY CODES: 24-Quaternary-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011500; N011500; LONG: W0772500; W0772500.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 1997-052432

UD - UPDATE CODE: 199717

Registro 5607 de 5614 - GeoRef 1997-2001

BK - BOOK TITLE: Galeras Volcano, Colombia; interdisciplinary study of a Decade Volcano.

BA - BOOK AUTHORS: Stix-John (editor); Calvache-V-Marta-Lucia (editor); Williams-Stanley-N (editor)

BF - BOOK AUTHOR AFFILIATION: Universite de Montreal, Departement de Geologie, Montreal, PQ, Canada; INGEOMINAS, Pasto, Colombia; Arizona State University, Tempe, AZ, United States

SO - SOURCE: Journal of Volcanology and Geothermal Research. 77; 1-4, 1997.

NT - NOTES: Special issue

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. Pages: 338. 1997.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

DE - DESCRIPTORS: Andes-; Colombia-; eruptions-; Galeras-; interpretation-; lava-; South-America; volcanoes-

CC - CATEGORY CODES: 24-Quaternary-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Monograph

NN - ANNOTATION: Individual papers are cited separately.

IL - ILLUSTRATION: illus. incl. tables.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 1997-052431

UD - UPDATE CODE: 199717

Registro 5608 de 5614 - GeoRef 1997-2001

TI - TITLE: Water balance and nutrient inputs in bulk precipitation in tropical montane cloud forest in Panama.

AU - AUTHORS: Cavelier-Jaime; Jaramillo-Maria; Solis-Daniel; de-Leon-Doris

AF - AUTHOR AFFILIATION: Universidad de los Andes, Departamento de Ciencias Biologicas, Bogota, Colombia

SO - SOURCE: Journal of Hydrology. 193; 1-4, Pages 83-96. 1997.

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1997.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

AB - ABSTRACT: The hydrological balance and nutrient inputs in water were measured in a lower montane rain forest (1200m) in Panama. Rainfall and throughfall were measured daily between July 1988 and July 1989 using a standard rain gauge and 50 longitudinal PVC collectors, respectively. Stemflow was measured daily between November 1990 and December 1991 in nine trees varying from 16 to 54cm diameter at breast height (dbh), using tygon collars. Rainfall and throughfall water samples were collected every 15 days between January and October 1989 for chemical analyses (pH, conductivity, NO (sub 3) (super -) , NO (sub 2) (super -) , NH (sub 4) (super +) , PO (sub 4) (super 3-) , SO (sub 4) (super 2-) , Ca (super 2+) , Cl (super -) , Mg (super 2+) , K (super +) , Mn, Fe and Si). Bulk precipitation was 3510 mm. Interception was 37.2%, net precipitation was 62.8%, of which, throughfall was 62.4% and stemflow was 0.4%. The probability distribution of throughfall as a proportion of bulk precipitation, showed that 82% of the total variability is lower than a bulk precipitation value of 1.0 and that there are higher values in this mountain forest than in a lowland rain forest in Brazil were this value was also calculated, suggesting that the canopy of this montane forest is more heterogeneous. In only 6 of 140 of the rain events, was net precipitation higher than bulk precipitation, suggesting that direct inputs of cloud water by fog interception, is not an important water source for this forest. Interception at Fortuna is the highest value yet reported for a tropical montane rain forest; it maybe attributed to a very tall canopy (20-30 m) and abundant epiphyte load. Nutrient inputs in water varied from 0.70 kg ha (super -1) per year of PO (sub 4) -P to 34.5 kg ha (super -1) per year of Cl. Leaching varied from 1.45 kg ha (super -1) per year for PO (sub 4) -P to 49.71 kg ha (super -1) per year of K. Net absorption by the canopy was measured for S (-7.0 kg ha (super -1) per year SO (sub 4) -S) while for N the total annual input was about the same as the annual throughfall. Annual fluxes of calcium, sodium and potassium in bulk precipitation in the Fortuna forest were in the upper range of values reported for other tropical montane sites, perhaps owing to the proximity to the Caribbean Sea. Nutrient inputs of N, P and K in throughfall are consistent with inputs of throughfall relative to other nutrient pathways in tropical and temperate forests.

DE - DESCRIPTORS: atmospheric-precipitation; Central-America; Central-Cordillera; ecology-; ecosystems-; forests-; Fortuna-Basin; hydrology-; measurement-; mountains-; nutrients-; Panama-; Plantae-; rain-forests; rainfall-; tropical-environment; water-balance

CC - CATEGORY CODES: 21-Hydrogeology; 22-Environmental-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N084300; N084300; LONG: W0821400; W0821400.

IL - ILLUSTRATION: Refs: 46; illus. incl. 4 tables.

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

IS - ISSN: 0022-1694

CO - CODEN: JHYDA7

AN - ACCESSION NUMBER: 1997-051720

UD - UPDATE CODE: 199717

Registro 5609 de 5614 - GeoRef 1997-2001

TI - TITLE: Responses of leaf anatomy to light environment in the tree fern Cyathea caracasana (Cyatheaceae) and its application to some ancient seed ferns.

AU - AUTHORS: Arens-Nan-Crystal

AF - AUTHOR AFFILIATION: Harvard University, Botanical Museum, Cambridge, MA, United States

SO - SOURCE: Palaios. 12; 1, Pages 84-94. 1997.

PB - PUBLISHER: Society of Economic Paleontologists and Mineralogists. Tulsa, OK, United States. 1997.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

DE - DESCRIPTORS: Alethopteris-; anatomy-; applications-; biometry-; Carboniferous-; Cenozoic-; classification-; Colombia-; Cyathea-; Cyathea-caracasana; ecology-; effects-; Europe-; Filicopsida-; Gymnospermae-; Holocene-; interpretation-; leaves-; living-taxa; morphology-; Neuropteris-; North-America; paleoecology-; Paleozoic-; Plantae-; Pteridophyta-; Pteridospermae-; Quaternary-; South-America; Spermatophyta-; statistical-analysis; tissues-; tropical-environment; ultrastructure-; Upper-Carboniferous; Westphalian-

CC - CATEGORY CODES: 09-Paleobotany

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 84; illus. incl. 4 tables.

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

IS - ISSN: 0883-1351

AN - ACCESSION NUMBER: 1997-048694

UD - UPDATE CODE: 199716

Registro 5610 de 5614 - GeoRef 1997-2001

TI - TITLE: Organic facies variations, source rock potential, and sea level changes in Cretaceous black shales of the Quebrada Ocal, upper Magdalena Valley, Colombia.

AU - AUTHORS: Mann-Ute; Stein-Ruediger

AF - AUTHOR AFFILIATION: Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Federal Republic of Germany

SO - SOURCE: AAPG Bulletin. 81; 4, Pages 556-576. 1997.

PB - PUBLISHER: American Association of Petroleum Geologists. Tulsa, OK, United States. 1997.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

AB - ABSTRACT: A 290-m-thick middle Cretaceous black shale sequence in the upper Magdalena Valley, a present-day intramontane basin located between the Central and Eastern cordilleras of Colombia, was investigated with organic-geochemical and microscopic analyses. As a result of the investigation, we were able to (1) differentiate four organic facies types, (2) estimate their source rock potential, and (3) integrate these facies into a sequence stratigraphic framework. The four organic facies types were type C, BC, B, and D. Type C contains a distinct terrigenous organic matter component in lowstand or highstand deposits. Organic facies type BC is characterized by an increase and a better preservation of marine organic matter. BC belongs to the lower part of the transgressive systems tract. Sediments of organic facies type B have the highest amount of marine organic matter due to excellent preservation under anoxic conditions. The absence of bioturbation and the enrichment of trace metals are further implications for deposition under anoxic conditions. Facies type B is found in the upper part of the transgressive systems tract and contains the best petroleum source rock potential. Facies B occurrence coincides with sea level highstand and correlates especially with a maximum flooding in northern South America during the Turonian. Organic facies type D is also related to highstand deposits, but shows a high rate of reworking and degradation of organic matter.

DE - DESCRIPTORS: black-shale; carbon-; chemical-composition; clastic-rocks; Colombia-; Cretaceous-; degradation-; fluvial-environment; Hondita-Formation; hydrogen-; lagoonal-environment; lithofacies-; Magdalena-Valley; marine-environment; Mesozoic-; Middle-Cretaceous; organic-carbon; organic-compounds; organic-materials; oxygen-; paleoenvironment-; petroleum-; Quebrada-Ocal; regression-; sea-level-changes; sedimentary-rocks; sequence-stratigraphy; shelf-environment; slope-environment; source-rocks; South-America; sulfur-; thickness-; transgression-

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

IL - ILLUSTRATION: Refs: 51; illus. incl. chart, strat. cols., 3 tables, sketch maps.

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: 1997-036282

UD - UPDATE CODE: 199712

Registro 5611 de 5614 - GeoRef 1997-2001

TI - TITLE: The Llanos Basin, Colombia; in search of greater stratigraphic resolution.

AU - AUTHORS: Duque-Caro-H

AF - AUTHOR AFFILIATION: Duque-Caro & Cia, Bogota, Colombia

SO - SOURCE: Journal of Petroleum Geology. 20; 1, Pages 96-99. 1997.

PB - PUBLISHER: Scientific Press. Beaconsfield, United Kingdom. 1997.

CP - COUNTRY OF PUBLICATION: United-Kingdom

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

DE - DESCRIPTORS: Andes-; biostratigraphy-; Cenozoic-; chronostratigraphy-; Colombia-; correlation-; eastern-Colombia; Eastern-Cordillera; lithostratigraphy-; Llanos-; Macarena-Range; microfossils-; nomenclature-; palynomorphs-; South-America; Tertiary-

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 10; chart, sketch map.

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

IS - ISSN: 0141-6421

AN - ACCESSION NUMBER: 1997-036085

UD - UPDATE CODE: 199712

Registro 5612 de 5614 - GeoRef 1997-2001

TI - TITLE: Ball clay development in the Americas.

AU - AUTHORS: Deems-Tom-F; Vincent-Tony

AF - AUTHOR AFFILIATION: United Ball Clays, 7003 Chadwick Drive, Brentwood, TN, United States

SO - SOURCE: Mining Engineering. 49; 2, Pages 30-33. 1997.

PB - PUBLISHER: Society for Mining, Metallurgy, and Exploration. Littleton, CO, United States. 1997.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

DE - DESCRIPTORS: Argentina-; Brazil-; Cenozoic-; clays-; Colombia-; history-; mining-; mining-geology; Mississippi-Embayment; Northern-Hemisphere; open-pit-mining; plasticity-; South-America; surface-mining; Tennessee-; Tertiary-; United-States; Venezuela-; western-Tennessee

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 5; illus.

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

IS - ISSN: 0026-5187

CO - CODEN: MIENAB

AN - ACCESSION NUMBER: 1997-033064

UD - UPDATE CODE: 199711

Registro 5613 de 5614 - GeoRef 1997-2001

TI - TITLE: Dynamic melting in plume heads; the formation of Gorgona komatiites and basalts.

AU - AUTHORS: Arndt-Nicholas-T; Kerr-Andrew-C; Tarney-John

AF - AUTHOR AFFILIATION: Universite de Rennes, Geosciences, Rennes, France

SO - SOURCE: Earth and Planetary Science Letters. 146; 1-2, Pages 289-301. 1997.

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. 1997.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

AB - ABSTRACT: The small Pacific island of Gorgona, off the coast of Colombia, is well known for its spectacular spinifex-textured komatiites. These high-Mg liquids, which have been linked to a late Cretaceous deep mantle plume, are part of a volcanic series with a wide range of trace-element compositions, from moderately enriched basalts (La/Sm (sub N) approximately 1.5) to extremely depleted ultramafic tuffs and picrites (La/Sm (sub N) approximately 0.2). Neither fractional crystallization, nor partial melting of a homogeneous mantle source, can account for this large variation: the source must have been chemically heterogeneous. Low (super 143) Nd/ (super 144) Nd in the more enriched basalts indicates some initial source heterogeneity but most of the variation in magma compositions is believed to result from dynamic melting during the ascent of a plume. Modelling of major- and trace-element compositions suggests that ultramafic magmas formed at approximately 60-100 km depth, and that the melt extraction that gave rise to their depleted sources started at still greater depths. The ultra-depleted lavas represent magmas derived directly from the hottest, most depleted parts of the plume; the more abundant moderately depleted basalts are interpreted as the products of pooling of liquids from throughout the melting region.

DE - DESCRIPTORS: basalts-; Colombia-; Cretaceous-; East-Pacific-Ocean-Islands; geochemistry-; Gorgona-Island; igneous-rocks; isotope-ratios; isotopes-; komatiite-; lithogeochemistry-; mafic-magmas; magmas-; magmatic-differentiation; major-elements; mantle-plumes; melting-; Mesozoic-; metals-; Nd-144-Nd-143; neodymium-; plutonic-rocks; rare-earths; South-America; spinifex-texture; stable-isotopes; textures-; trace-elements; ultramafics-; volcanic-rocks

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N030000; N030000; LONG: W0781500; W0781500.

IL - ILLUSTRATION: Refs: 45; illus. incl. 2 tables.

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

IS - ISSN: 0012-821X

CO - CODEN: EPSLA2

AN - ACCESSION NUMBER: 1997-022063

UD - UPDATE CODE: 199708

Registro 5614 de 5614 - GeoRef 1997-2001

TI - TITLE: Generation and expulsion of petroleum and gas from Almond Formation coal, greater Green River basin, Wyoming.

AU - AUTHORS: Garcia-Gonzalez-Mario; Surdam-Ronald-C; Lee-Milton-L

AF - AUTHOR AFFILIATION: Universidad Industrial de Santander, Bucaramanga, Colombia

SO - SOURCE: AAPG Bulletin. 81; 1, Pages 62-81. 1997.

PB - PUBLISHER: American Association of Petroleum Geologists. Tulsa, OK, United States. 1997.

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 1997

LA - LANGUAGE: English

AB - ABSTRACT: Petrographic and geochemical studies of coal from the Almond Formation in the greater Green River basin demonstrate that the coal contains important volumes of stored liquid petroleum, as well as methane. Modeling indicates that at the basin center, most of the oil generated in the coal has been thermally cracked to gas, whereas at the basin flank the oil-to-gas reaction has barely proceeded. Several new concepts are presented about the mechanism of petroleum generation in coal based on (1) natural maturation trends gleaned from examination of Almond coal samples from different burial depths and (2) similar maturation trends observed in hydrous pyrolysis experiments using immature Almond coal samples. These new concepts show that the oil in the coal was generated during the alteration of desmocollinite and liptinite macerals to exsudatinite (waxy oil) and inertinite solid residue; that the waxy oil was initially stored in porous structures and subsequently in vesicles as the coal matured under increasing temperature; that primary migration of the oil occurred as the generation of a sufficient volume of exsudatinite microfractured the vitrinite-semifusinite vesicles, interconnecting vesicles, and pores; and that the thermal cracking of exsudatinite generated a sufficient volume of gas to fracture the vesiculated coal as pore pressure increased and allowed migration of hydrocarbons out of the coal.

DE - DESCRIPTORS: Almond-Formation; carbon-; chromatograms-; clastic-rocks; coal-; Cretaceous-; desmocollinite-; exinite-; exsudatinite-; gas-chromatograms; genesis-; geochemistry-; Green-River-basin; inertinite-; macerals-; maturity-; Mesozoic-; migration-; models-; natural-gas; NMR-spectra; organic-residues; petrography-; petroleum-; porosity-; pyrolysis-; rank-; reflectance-; sedimentary-rocks; shale-; spectra-; United-States; Upper-Cretaceous; vitrinite-; wells-; Wyoming-

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 23; illus. incl. 6 tables, sketch map.

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: 1997-016972