No. Registros Solicitud 1 5614 colombia

CO - CODEN: #00291

AN - ACCESSION NUMBER: 2004-066936

UD - UPDATE CODE: 200420

Registro 52 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: The interandean arid track and the origins of neotropical aridity; brief review.

AU - AUTHORS: Ochsenius-Claudio

BK - BOOK TITLE: In: The neotropical aridity; the search for the origins of South American xerophylous worlds and their amazing landscapes; a selected collection of papers from a geological time perspective.

BA - BOOK AUTHORS: Ochsenius-Claudio

SO - SOURCE: Geowissenschaftliche Beitraege. 10; Pages 67-95. 1999.

PB - PUBLISHER: Carl-Christian Ochsenius - Stiftung (CCOS). Singen, Federal Republic of Germany. 1999.

CP - COUNTRY OF PUBLICATION: Federal-Republic-of-Germany

PY - PUBLICATION YEAR: 1999

LA - LANGUAGE: English

DE - DESCRIPTORS: Andes-; arid-environment; biogeography-; Cenozoic-; Colombia-; Cretaceous-; Ecuador-; endemic-taxa; floral-list; landform-description; Mesozoic-; mountains-; paleogeography-; South-America; terrestrial-environment; Tertiary-; tropical-environment; Venezuela-

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: sects., geol. sketch maps.

RF - REFERENCE SOURCE: GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe, Hanover, Germany

IB - ISBN: 956-7383-03-0

CO - CODEN: #05762

AN - ACCESSION NUMBER: 2004-066392

UD - UPDATE CODE: 200420

Registro 53 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Provenance of a late Proterozoic-Early Cambrian basin, Sierras de Cordoba, Argentina.

AU - AUTHORS: Schwartz-Joshua-J; Gromet-L-Peter

AF - AUTHOR AFFILIATION: Brown University, Department of Geological Sciences, Providence, RI, United States

SO - SOURCE: Precambrian Research. 129; 1-2, Pages 1-21. 2004.

PB - PUBLISHER: Elsevier. Amsterdam, International. 2004.

CP - COUNTRY OF PUBLICATION: International

PY - PUBLICATION YEAR: 2004

LA - LANGUAGE: English

AB - ABSTRACT: Detrital zircons in metasedimentary rocks of Cambrian or older age in the Sierras de Cordoba provide information on sources of continental detritus on the western paleo-margin of Gondwana. Analysis of single zircon grains indicates dominant populations of Neoproterozoic ( approximately 600-700 Ma) and Mesoproterozoic (950-1050 Ma) age, and a limited presence of Paleoproterozoic ( approximately 1900 Ma) zircon. Additional constraints on provenance are provided by the Pb isotopic compositions of peraluminous granites derived from the metasedimentary section. These compositions fall within the distinctive (super 207) Pb-rich Gondwana provinces and therefore appear to rule out a Laurentian source such as the Argentine Precordillera. We interpret the sources of the Neoproterozoic and Paleoproterozoic zircons to be Gondwanan, most likely derived from the cratonic regions of South America and/or the once contiguous cratons of southwestern Africa. The Mesoproterozoic population constitutes more than half the analyzed grains and could be derived from approximately 1.0 Ga rocks exposed along the western margin of the Amazon craton (e.g. Sunsas belt, Colombian Andes) and/or its rifted equivalents (e.g. Arequipa Massif). We conclude that the metasedimentary rocks in the Sierras de Cordoba and related rocks to the north in the Puncoviscana Formation developed marginal to Gondwana when much of the locally exposed crust was composed of Mesoproterozoic rocks, although these rocks are now sparingly exposed. The most likely sources for Mesoproterozoic sediment are the Arequipa-Antofalla terrane, the Borborema Province and the Kalahari craton, all of which were proximal to the Sierras Pampeanas in late Neoproterozoic reconstructions. Additional constraints on the relative paleogeographic locations of the Arequipa-Antofalla terrane, the Kalahari craton and the Puncoviscana trough in the late Neoproterozoic are needed to distinguish among these potential sources.

DE - DESCRIPTORS: absolute-age; Andes-; Arequipa-Massif; Arequipa-Antofalla-Terrane; Argentina-; Borborema-; Brazil-; Cambrian-; Colombia-; dates-; granites-; igneous-rocks; ion-probe-data; isotope-ratios; isotopes-; Kalahari-Craton; lead-; Lower-Cambrian; mass-spectra; Mesoproterozoic-; metals-; metamorphic-rocks; metasedimentary-rocks; Nd-144-Nd-143; neodymium-; Neoproterozoic-; nesosilicates-; orthosilicates-; paleogeography-; Paleozoic-; Pampean-Mountains; Pb-206-Pb-204; Pb-207-Pb-206; Pb-208-Pb-206; plutonic-rocks; Precambrian-; Precordillera-; Proterozoic-; provenance-; Puncoviscana-Formation; radioactive-isotopes; rare-earths; reconstruction-; Rodinia-; SHRIMP-data; Sierras-de-Cordoba; silicates-; South-America; spectra-; stable-isotopes; Sunsas-Belt; tectonics-; U-Pb; upper-Precambrian; zircon-

CC - CATEGORY CODES: 16-Structural-geology; 03-Geochronology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

IL - ILLUSTRATION: Refs: 110; illus. incl. 3 tables, sketch map.

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

IS - ISSN: 0301-9268

CO - CODEN: PCBRBY

AN - ACCESSION NUMBER: 2004-065571

UD - UPDATE CODE: 200419

Registro 54 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Parameterization of multichromatic tornillo signals observed at Galeras Volcano (Colombia).

AU - AUTHORS: Seidl-Dieter; Hellweg-Margaret

AF - AUTHOR AFFILIATION: Bundesanstalt fuer Geowissenschaften und Rohstoffe, Seismologisches Zentralobservatorium Graefenberg, Erlangen, Federal Republic of Germany

BK - BOOK TITLE: In: Understanding volcanoes through multiparameter measurements and their interpretation; in memory of Bruno Martinelli.

BA - BOOK AUTHORS: Hellweg-Peggy (editor); Calvache-Marta (editor); Falsaperla-Susanna (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 125; 1-2, Pages 171-189. 2003.

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

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: In the past decade several of the ash eruptions at Galeras Volcano, Colombia, have been preceded by tornillos. These unusual tremor wavelets have quasi-sinusoidal waveforms with screw-like envelope profiles and can last up to several minutes. A swarm of tornillos occurred at Galeras Volcano between 8 December 1999 and 12 February 2000. These tornillos appear to be more complex than those previously recorded with the broadband instruments or with the short-period network of the Observatorio Vulcanologico y Sismologico in Pasto. They are multichromatic with a varying number of narrow spectral peaks between 1 and 20 Hz. We describe a procedure for parameterizing the tornillo signals in the time and frequency domains to determine signal parameters. In addition to wavelets like the tornillos, the procedure can be applied to random signals such as volcanic tremor. We derive distribution and correlation functions for the signal parameters determined from the swarm. These provide, along with the signal signature, constraints for modelling variations of the source process. From these observations we derive qualitative conclusions about the characteristics of differential equations which describe the underlying processes and excitation mechanisms as forced or self-excited oscillators.

DE - DESCRIPTORS: Andes-; Colombia-; earthquakes-; factors-; frequency-; Galeras-; histograms-; models-; oscillations-; seismicity-; seismograms-; signals-; simulation-; South-America; southwestern-Colombia; spectral-analysis; statistical-analysis; swarms-; synthetic-seismograms; tornillos-; Van-der-Pol-equation; volcanic-earthquakes; volcanism-; volcanoes-

CC - CATEGORY CODES: 24-Quaternary-geology; 19-Seismology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011300; N011300; LONG: W0772200; W0772200.

IL - ILLUSTRATION: Refs: 27; illus. incl. 2 tables.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 2004-065551

UD - UPDATE CODE: 200419

Registro 55 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Tornillos beneath Tongariro Volcano, New Zealand.

AU - AUTHORS: Hagerty-Mike; Benites-Rafael

AF - AUTHOR AFFILIATION: Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand

BK - BOOK TITLE: In: Understanding volcanoes through multiparameter measurements and their interpretation; in memory of Bruno Martinelli.

BA - BOOK AUTHORS: Hellweg-Peggy (editor); Calvache-Marta (editor); Falsaperla-Susanna (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 125; 1-2, Pages 151-169. 2003.

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

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: Unusual low-frequency seismic events have recently begun to occur beneath Tongariro Volcano, New Zealand. Because the seismic waveforms appear similar to waveforms called tornillos, which have been recorded at Galeras Volcano in Colombia and have been found to precede small to medium-sized ash eruptions there by several weeks to months, we are monitoring them closely. At Tongariro, these events are characterised by small-amplitude, monochromatic or multichromatic waveforms that decay slowly with time, features that suggest a source involving magmatic or hydrothermal fluids within a zone surrounded by hard rock. The frequency content of monochromatic events is typically between 1 and 3 Hz and is often found to be peaked at f = 1.2 Hz. Event durations range from about 10 to 80 s; the appearance of the shorter-duration events is identical to so-called LP or long-period events; the LPs and tornillos appear to be co-located so that the only difference between LPs and tornillos is the extended duration of the latter. These events have been identified in the seismograms of the permanent monitoring station KAVZ since at least January, 2001, occurring at a rate of about one per month. During June-August, 2001, the rate of occurrence gradually increased, peaking in September, 2001, at several events per day. We deployed two broadband and several short-period seismometers at close distances to the expected source location. The resulting seismograms show a complex mixture of seismic waves, originating from shallow depth beneath the area of the Te Maari Craters, located approximately 0.5 km from the nearest station. The close range, broadband records reveal some interesting details about the tornillo source. The tornillo waveform is found to consist of two parts: a low-frequency (f approximately 1.2 Hz) part and a higher-frequency (f>3 Hz) part. The high-frequency energy travels at body wave speeds (c approximately 3.0 km/s) while the low-frequency energy travels at the speed of shear or surface waves in the shallow crust (c approximately 1 km/s). Interestingly, for some events, the low-frequency waves arrive before the high-frequency body waves at the closest station. This, and comparison with several LP events, suggests a spatial separation of the high- and low-frequency sources, with the low-frequency energy originating at shallow depth and acting as a trigger for the release of tectonic stress at greater depth, in the form of high-frequency body waves.

DE - DESCRIPTORS: Australasia-; earthquakes-; elastic-waves; frequency-; genesis-; kinematics-; long-period-waves; monitoring-; New-Zealand; North-Island; Q-; seismicity-; seismograms-; Tongariro-; tornillos-; volcanic-earthquakes; volcanism-; volcanoes-; waveforms-

CC - CATEGORY CODES: 24-Quaternary-geology; 19-Seismology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: S391200; S391200; LONG: E1753600; E1753600.

IL - ILLUSTRATION: Refs: 25; illus. incl. sect.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 2004-065550

UD - UPDATE CODE: 200419

Registro 56 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Continuous gas monitoring at Galeras Volcano, Colombia; first evidence.

AU - AUTHORS: Faber-E; Moran-C; Poggenburg-J; Garzon-G; Teschner-M

AF - AUTHOR AFFILIATION: Federal Institute for Geosciences and Natural Resources, Hanover, Federal Republic of Germany

BK - BOOK TITLE: In: Understanding volcanoes through multiparameter measurements and their interpretation; in memory of Bruno Martinelli.

BA - BOOK AUTHORS: Hellweg-Peggy (editor); Calvache-Marta (editor); Falsaperla-Susanna (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 125; 1-2, Pages 13-23. 2003.

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

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: This paper describes a system of instruments for continuously monitoring fumarolic gases which is installed at Galeras Volcano, Colombia. Several parameters such as the concentration of CO (sub 2) and Rn in the fumarolic emissions, as well as the temperature of the gases and their pressure are measured every 6 s. We report variations in these parameters which were observed during a short flurry of seismic activity at the volcano. At this stage, it is uncertain whether the changes in the parameters are directly associated with volcanic processes. From the data presented here, we can conclude that ambient air can enter the fumarolic vent system. In consequence, the fumarole may be influenced by the direction and strength of the wind.

DE - DESCRIPTORS: Andes-; carbon-dioxide; Colombia-; concentration-; effects-; fumaroles-; Galeras-; gases-; geochemistry-; instruments-; isotopes-; measurement-; monitoring-; noble-gases; oscillations-; pressure-; radioactive-isotopes; radon-; Rn-222; South-America; southwestern-Colombia; systems-; temperature-; variations-; volcanism-; volcanoes-; winds-

CC - CATEGORY CODES: 24-Quaternary-geology; 02D-Isotope-geochemistry

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011300; N011300; LONG: W0772200; W0772200.

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

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 2004-065542

UD - UPDATE CODE: 200419

Registro 57 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: The multiparameter station at Galeras Volcano (Colombia); concept and realization.

AU - AUTHORS: Seidl-Dieter; Hellweg-Margaret; Calvache-Marta; Gomez-Diego; Ortega-Adriana; Torres-Roberto; Boeker-Franz; Buttkus-Burkhard; Faber-Eckhard; Greinwald-Siegfried

AF - AUTHOR AFFILIATION: Bundesanstalt fuer Geowissenschaften und Rohstoffe, Seismologisches Zentralobservatorium Graefenberg, Erlangen, Federal Republic of Germany

BK - BOOK TITLE: In: Understanding volcanoes through multiparameter measurements and their interpretation; in memory of Bruno Martinelli.

BA - BOOK AUTHORS: Hellweg-Peggy (editor); Calvache-Marta (editor); Falsaperla-Susanna (editor)

SO - SOURCE: Journal of Volcanology and Geothermal Research. 125; 1-2, Pages 1-12. 2003.

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

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

AB - ABSTRACT: Volcanoes are complex systems, in which the interaction of many different physical and chemical factors and processes contribute to changes in activity. In the past 40 years, our ability to observe and quantify short-term changes in a volcano's activity has improved due to the installation of seismometers and tiltmeters and the continuous records they provide. However, due to instrumental limitations, the observations have mainly been used phenomenologically, to draw inferences about possible changes on the basis of previous experience. Since 1995, the Bundesanstalt fur Geowissenschaften und Rohstoffe (BGR) and the Instituto de Investigacion e Informacion Geocientifica, Minero-Ambiental y Nuclear (INGEOMINAS) have been working to develop and deploy a multiparameter (MP) station on Galeras Volcano, Colombia. This station is designed to concurrently measure various geophysical and geochemical parameters. It includes three broadband seismometers at the crater rim, as well as a more remotely located, broadband seismic reference. At other locations in the crater or on the rim, electromagnetic probes, an infrasound sensor and a weather station are operating. The data from these sensors are digitized at each site with 24-bit digitizers and transmitted by spread-spectrum radio, via repeater when necessary, to the Observatorio Vulcanologico y Sismologico (OVP) in the city of Pasto. There they are received and displayed on a networked personal computer and recorded continuously. The data flow into the routine analysis procedures of the OVP and the continuous data are archived on CD. In addition to the other sensors, a system of specially developed sensors continuously monitors the chemistry and physics of the gases at fumaroles on the active cone. The data from this system are also transmitted in realtime to OVP and recorded. The continuous recordings of the MP station are supplemented by regular thermographic measurements of the surface temperature in the crater using an infrared camera. Joint analysis and interpretation of the data streams from the many sensors of the MP station will improve our understanding of the physical processes occurring in Galeras Volcano.

DE - DESCRIPTORS: acoustical-waves; airborne-methods; Andes-; Colombia-; data-acquisition; data-management; data-processing; digital-data; electromagnetic-field; Galeras-; information-management; infrared-spectra; infrasound-; instruments-; international-cooperation; measurement-; monitoring-; observations-; observatories-; remote-sensing; resistivity-; seismic-networks; seismicity-; South-America; southwestern-Colombia; spectra-; systems-; telemetry-; thermal-anomalies; volcanoes-; waveforms-

CC - CATEGORY CODES: 24-Quaternary-geology; 20-Applied-geophysics

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N011300; N011300; LONG: W0772200; W0772200.

IL - ILLUSTRATION: Refs: 20; illus. incl. sects., sketch map.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 2004-065541

UD - UPDATE CODE: 200419

Registro 58 de 5614 - GeoRef : 2002-2004/12

BK - BOOK TITLE: Understanding volcanoes through multiparameter measurements and their interpretation; in memory of Bruno Martinelli.

BA - BOOK AUTHORS: Hellweg-Peggy (editor); Calvache-Marta (editor); Falsaperla-Susanna (editor)

BF - BOOK AUTHOR AFFILIATION: University of California at Berkeley, Berkeley Seismological Laboratory, Berkeley, CA, United States; Observatorio Vulcanologico de Pasto, Colombia; Istituto Nazionale di Geofisica e Vulcanologia, Italy

SO - SOURCE: Journal of Volcanology and Geothermal Research. 125; 1-2, 2003.

PB - PUBLISHER: Elsevier. Amsterdam, Netherlands. Pages: 189. 2003.

CP - COUNTRY OF PUBLICATION: Netherlands

PY - PUBLICATION YEAR: 2003

LA - LANGUAGE: English

DE - DESCRIPTORS: interpretation-; measurement-; monitoring-; volcanism-; 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. sects., tables, geol. sketch maps.

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

IS - ISSN: 0377-0273

CO - CODEN: JVGRDQ

AN - ACCESSION NUMBER: 2004-065540

UD - UPDATE CODE: 200419

Registro 59 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Temperature and salinity changes in the Caribbean Sea during glacial/ interglacial intervals as inferred from elemental and isotopic data.

AU - AUTHORS: Mora-German; Martinez-Ignacio

AF - AUTHOR AFFILIATION: Iowa State University, Department of Geological and Atmospheric Sciences, Ames, IA, United States

BK - BOOK TITLE: In: Geological Society of America, 2003 annual meeting.

BA - BOOK AUTHORS: Anonymous

SO - SOURCE: Abstracts with Programs - Geological Society of America. 35; 6, Pages 540. 2003.

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

RP - RESEARCH PROGRAM: ODP (Ocean Drilling Program)

CP - COUNTRY OF PUBLICATION: United-States

PY - PUBLICATION YEAR: 2003

CN - CONFERENCE INFORMATION: Geological Society of America, 2003 annual meeting. Seattle, WA, United States. Nov. 2-5, 2003.

LA - LANGUAGE: English

AB - ABSTRACT: The tropics play a critical role in controlling global climate as large amounts of energy and moisture are exported from low latitudes to temperate regions. Consequently it is important to understand tropical climate variations to assess possible global teleconnections. Here we investigate the possibility of using a marine core from the Caribbean Sea to assess changes in the hydrological balance of the region. For this purpose, we study the upper 20 m of ODP Site 999A from the Colombia Basin. Specimens of planktonic foraminifera (G. sacculifer and Neogloboquadrina dutertrei) were manually picked out of sediment samples, and their oxygen-isotopic composition was determined. The studied foraminiferal tests exhibit oxygen isotope values that fluctuate from +1.4 per mil to -0.8 per mil. Based on a comparison of the obtained isotopic values with the standard oxygen-isotope stages for the Quaternary, we conclude that the studied interval encompasses the last approximately 400,000 years. Additional chronostratigraphic control was provided by the relative abundance of Globorotalia menardii, G. inflata, and G. truncatulinoides. In parallel to the oxygen isotope analyses, magnesium/calcium (Mg/Ca) ratios were determined on foraminiferal tests to determine past changes in temperature and salinity of surface waters in the Caribbean Sea. Mg/Ca ratios range from 8.0 mmol/mol to 2.9 mmol/mol. Using published temperature calibrations, the obtained Mg/Ca ratios indicate that sea-surface temperatures have varied by up to 5˚ degrees C during the last 400,000 years. Because the oxygen-isotopic composition of foraminifera depends on that of seawater and temperature, the obtained Mg/Ca ratios can be used to assess the temperature-dependant isotope effect. Consequently the down-core residuals of oxygen isotope ratios of foraminifera reflect the variability in the oxygen isotopic composition of seawater through time. Residuals of isotope values for the studied core indicate significant changes in the isotopic composition of seawater that we correlate with the intensity of evaporation at the site. Since evaporation in the Caribbean Sea is closely coupled with the passage of the Inter-tropical Convergence Zone (ITCZ), we conclude that fluctuations in the intensity or zonality of the ITCZ exert a significant control on the amount of energy and moisture exported to mid-latitudes.