No. Registros Solicitud 1 5614 colombia

Registro 425 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: La geologia y la geofisica en Colombia; Desarrollo, estado actual y perspectivas

Translated Title: Geology and geophysics in Colombia; development, present conditions and future trends.

AU - AUTHORS: Briceno-Luis-A; Mojica-Jairo

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 161-198. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English; German

AB - ABSTRACT: Based on their own experience, opinions from other colleagues, the results of a specially designed poll, and a broad bibliographic consult, the authors have elaborated a synthesis of the historical development, present state, and perspectives of the Geology and Geophysics in Colombia. Particularly, this study has to deal with different aspects related to: 1) technical, professional and graduate qualification; 2) financial support and limitations in doing geological and geophysical research, and its type and quality of the work that presently is going on, at the different institutions; 3) publications, libraries, basic instrumentation and equipment; 4) professional associations and control organisms; 5)trends and development perspectives for the geosciences in the near future; conclusions and recommendations.

DE - DESCRIPTORS: academic-institutions; Colombia-; education-; financing-; geology-; geophysics-; practice-; publications-; research-; South-America

CC - CATEGORY CODES: 15-Miscellaneous

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

NN - ANNOTATION: Includes appendix.

IL - ILLUSTRATION: Refs: 54; illus. incl. 4 tables.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027098

UD - UPDATE CODE: 200309

Registro 426 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Cambios temporales en algunos elementos meteorologicos, a diferentes altitudes y en la zona central de Colombia, asociados a la erupcion del Volcan Nevado del Ruiz ocurrida el 13 de noviembre de 1985 y altura de la nube de ceniza

Translated Title: Temporary variations of some meteorological elements at different elevations associated with the 13 November 1985 Nevado del Ruiz volcanic eruption, and elevation of the ash cloud, central Colombia.

AU - AUTHORS: Eslava-R-Jesus-A

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Santafe de Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 151-160. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: Temporal variations of some meteorological elements occurred at different altitudes, are determinate for the central part of Colombia, like consequence of the eruptive event from Nevado del Ruiz volcano on November 13 of 1985. The changes of the values of the elements that characterize the tropopause are quantified. Also, are discuss the different hypothesis about the maximum rise of the both column and ashes cloud, formed by the pyroclastic material from the eruptive event.

DE - DESCRIPTORS: ash-clouds; atmosphere-; atmospheric-pressure; Colombia-; eruptions-; igneous-rocks; moisture-; Nevado-del-Ruiz; pyroclastics-; South-America; temperature-; Tolima-Colombia; troposphere-; volcanic-rocks; volcanoes-; wind-transport

CC - CATEGORY CODES: 24-Quaternary-geology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N045300; N045300; LONG: W0752200; W0752200.

IL - ILLUSTRATION: Refs: 17; illus. incl. sect., 8 tables, geol. sketch map.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027097

UD - UPDATE CODE: 200309

Registro 427 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Nuevas manifestaciones igneas basicas en el flanco occidental de la Cordillera Oriental, Colombia

Translated Title: New basic igneous rock occurrences in the western flank of the Eastern Cordillera, Colombia.

AU - AUTHORS: Moreno-Murillo-Juan-Manuel; Concha-Perdomo-Ana-Elena

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 143-150. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: New basic igneous rocks generally dykes and sills are described and located on the central part, western flank of the Eastern cordillera. According to the preliminary results of the petrographic and chemical analyses of major elements, these rocks correspond with the similar gabbroic rocks reported at the southern part of the study area.

DE - DESCRIPTORS: Albian-; Andes-; Aptian-; Boyaca-Colombia; chemical-composition; Colombia-; Coniacian-; Cretaceous-; Cundinamarca-Colombia; dikes-; Eastern-Cordillera; gabbros-; geochemistry-; igneous-rocks; intrusions-; Lower-Cretaceous; Mesozoic-; plutonic-rocks; Senonian-; sills-; South-America; Turonian-; Upper-Cretaceous

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N050500; N055000; LONG: W0735000; W0743000.

IL - ILLUSTRATION: Refs: 14; illus. incl. 2 tables, geol. sketch maps.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027096

UD - UPDATE CODE: 200309

Registro 428 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Caracterizacion y clasificacion geoquimica de las Rocas volcanicas de Providencia en el Caribe colombiano

Translated Title: Geochemical characterization and classification of volcanic rocks in Providencia Island, Caribbean Sea, Colombia.

AU - AUTHORS: Concha-Ana-Elena; Macia-Carlos

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 137-142. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: The characterization and geochemical classification of the volcanites present at the Providencia Island in the Colombian Caribbean are presented in this summary. The volcanic rocks cropping out in Providencia indicate mainly a sub-alkaline character; some of them show an alkaline trend series. The subalkalines present two well defined trends, one rich in K and the other "normal". These rocks were classified as aluminic basalts (high Al), potassium aluminic basalts, shoshonitic basalts, potassic basaltic andesites, andesites, dacites, potassic dacites and rhyolites.

DE - DESCRIPTORS: alkalic-composition; aluminum-; andesites-; Atlantic-Ocean; basalts-; Caribbean-Sea; Cenozoic-; Colombia-; dacites-; igneous-rocks; metals-; middle-Miocene; Miocene-; Neogene-; North-Atlantic; potassic-composition; Providencia-Island; rhyolites-; shoshonite-; South-America; spectra-; Tertiary-; volcanic-rocks; X-ray-fluorescence-spectra

CC - CATEGORY CODES: 02C-Geochemistry-of-rocks,-soils,-and-sediments

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N132000; N132200; LONG: W0812100; W0812300.

IL - ILLUSTRATION: Refs: 13; illus.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027095

UD - UPDATE CODE: 200309

Registro 429 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Los sedimentos precambricos del Guainia y el origen de las ocurrencias auriferas en el Borde occidental del Escudo de Guayanas

Translated Title: Precambrian sediments of the Guainia Department and the origin of auriferous occurrences on the western margin of the Guyana Shield.

AU - AUTHORS: Galvis-Vergara-Jaime

AF - AUTHOR AFFILIATION: Consultant, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 119-136. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: This paper contains petrographic and field observations about the lithologic units observed in the Caranacoa and Naquen Ranges, situated in Guainia Department, Colombia. It is postulated a hypothesis about the gold occurrences known in those ranges. Such hypothesis proposes a gold precipitation from chemically reducing brines caused by oxygen expelled by anaerobic organisms.

DE - DESCRIPTORS: biogenic-processes; Caranacoa-Hills; clastic-rocks; Colombia-; conglomerate-; gold-ores; granites-; graphite-; Guainia-Colombia; Guyana-Shield; igneous-rocks; metal-ores; metamorphic-rocks; metamorphism-; metasedimentary-rocks; metavolcanic-rocks; migmatization-; mineral-deposits,-genesis; Naquen-Hills; native-elements; plutonic-rocks; Precambrian-; precipitation-; ring-silicates; sandstone-; sedimentary-rocks; silicates-; slates-; South-America; tourmaline-

CC - CATEGORY CODES: 27A-Economic-geology,-geology-of-ore-deposits; 05A-Igneous-and-metamorphic-petrology

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N013000; N015000; LONG: W0684500; W0691500.

IL - ILLUSTRATION: Refs: 12; illus. incl. 13 plates, geol. sketch maps.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027094

UD - UPDATE CODE: 200309

Registro 430 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Los foraminiferos y minerales autigenicos de la Formacion Umir (Seccion Quebrada La Julia, Valle Medio del Magdalena); registro de una Laguna costera a finales del Cretacico Superior (Maestrichtiano)

Translated Title: Foraminifera and authigenic minerals of the Umir Formation (La Julia Gorge section, Middle Magdalena Valley); record of a coastal lagoon at the end of the Upper Cretaceous (Maastrichtian).

AU - AUTHORS: Tchegliakova-Nadejda

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 107-117. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: The fact of finding a plenty microfaunistic assemblage that is represented chiefly by foraminifera and ostracodes, calcareous algae and fish's teeth in smaller number with a rich and diverse association of authigenic minerals that are along the Umir Formation (Quebrada La Julia Section, Middle Magdalena Valley, Colombia) allowed the establishment of an unstable ecosystem. It is characterized by environmental stress which is reflected on the strong fluctuations of the oxygenation of sedimentation depths, low pH, an unstable equilibrium in the primary organic productivity and the remarkable presence of opportunistic forms during the whole time this unit was deposited (Maastrichtian). These features resemble an environment of coastal lagoon. In conclusion, the Umir Formation represents the final record of great cretaceous depositional marine cycle (at least in the basin of Middle Magdalena Valley). This is reflected in the overlapping of the continental facies over marine facies. These facts, allowing the continental environments to be predicted, would predominate during the Tertiary in the study zone.

DE - DESCRIPTORS: algae-; Arthropoda-; authigenic-minerals; calcareous-algae; Chordata-; Colombia-; Cretaceous-; Crustacea-; Foraminifera-; Invertebrata-; La-Julia-Gorge; Mandibulata-; marine-environment; Mesozoic-; microfossils-; Middle-Magdalena-Valley; Ostracoda-; paleoenvironment-; Pisces-; Plantae-; Protista-; Santander-Colombia; South-America; teeth-; terrestrial-environment; Umir-Formation; Upper-Cretaceous; Vertebrata-

CC - CATEGORY CODES: 12-Stratigraphy

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N071500; N074500; LONG: W0730000; W0740000.

IL - ILLUSTRATION: Refs: 54; illus. incl. block diag., strat. col., 1 plate, geol. sketch map.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027093

UD - UPDATE CODE: 200309

Registro 431 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Arcos y lineamientos de direccion Noroeste-Sureste en las Cuencas subandinas de Venezuela y Colombia

Translated Title: Northwest-southeast trending arches and lineaments in the Andean piedmont basins of Venezuela and Colombia.

AU - AUTHORS: Ujueta-L-Guillermo

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 95-106. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: From some time back, various structural characteristics identified in the Llanos Orientales and Barinas-Apure basins known as arcs are found to be approximately perpendicular to the Eastern Cordillera of Colombia and the Venezuelan Andes. Such arcs were identified by means of magnetic and seismic data as well as stratigraphic data from the various oil wells drilled. Recently, as a result of the pooling of data from different sources and disciplines, the presence of deep-seated ancestral (Proterozoic?) Northwest-Southeast trending fractures was determined. These fractures have been reactivated in different epochs, are referred to as lineaments of which eleven are known in the Eastern Cordillera of Colombia in the Girardot-Cucuta sector and four in the Merida Andes. These lineaments have lengths that vary between 400 and 1,200 km being spaced every 40 to 50 km in Colombia and multiples of this in Venezuela. The observed lineaments represent the surficial traces of the edges of crustal blocks whose differential displacements have defined the tectonic and sedimentological development of the Andean Cordillera as well as the sub-andean basins. In these last basins, the aforementioned blocks roughly coincide with the recognized and accepted position and orientation of the so-called arcs. It is believed that there is a direct connection between the fractures present in the Guayanan Craton and those structures that appear in the Andean chain as well as the series of uplifted or downthrown blocks (horsts and grabens) of Northwest-Southeast trend in the Colombian and Venezuelan Subandean basins. It is then proposed that the so-called arcs are none others than the edges of the uplifted blocks defined by the NW-SE lineaments. This proposal would then become an important tool for hydrocarbon prospection.

DE - DESCRIPTORS: Andes-; Andes-de-Merida; Arauca-Santa-Barbara-Arch; arches-; Barinas-Apure-Basin; basins-; Cenozoic-; Colombia-; Eastern-Cordillera; Eastern-Plain-Basin; Eastern-Venezuela-Basin; El-Baul-Arch; Eocene-; faults-; grabens-; Guyana-Shield; horsts-; Jurassic-; lineaments-; Merida-Arch; Mesozoic-; Paleogene-; Paleozoic-; Permian-; petroleum-; petroleum-exploration; piedmonts-; Putumayo-Basin; South-America; structural-traps; systems-; tectonics-; Tertiary-; traps-; Triassic-; uplifts-; Vaupes-Guaviare-Arch; Venezuela-

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N070000; N090000; LONG: W0710000; W0730000.

IL - ILLUSTRATION: Refs: 28; illus. incl. block diag., sect., geol. sketch maps.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027092

UD - UPDATE CODE: 200309

Registro 432 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Lineamientos de direccion Noroeste-Sureste en los Andes venezolanos

Translated Title: Northwest-southeast trending lineaments in the Andes of Venezuela.

AU - AUTHORS: Ujueta-L-Guillermo

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 75-93. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: Five regional type structural elements perpendicular to the main trend of the Venezuelan Andes have been recognised and are being referred to as the: Depresion de Cucuta o Tachira Lineament, Caparo Lineament, Western Maracaibo Lake Lineament, Eastern Maracaibo Lake Lineament and Depresion de Barquisimeto Lineament. These lineaments are characteristically rectilinear, reasonably parallel to each other, and can be traced over hundreds of kilometers. They cut through both the Maracaibo Lake and Barinas-Apure basins up to the surface where they are recognized as geomorphological anomalies. Within the Andean Ranges and out on the Guayanan Craton they are evident by the alignment of topographic depressions as well as their control over the drainage patterns. Apart from all the above, where the lineaments intersect, a wide variety of geological anomalies are found such as: thickenings and pinch-outs to as much as complete disappearance of rock outcrops, fault and fold truncation, structural displacement, thickness and/or facial changes; all of which aid in tracing out the lineaments. Magnetic data mostly in the Barinas-Apure basin have also shown the presence of structural highs cut off by NW-SE trending faults and some NW-SE trending morphostructural characteristics coincide with the gravimetric contouring. Magmatic activity cannot, at the present time, be directly related to these lineaments. It is, nevertheless, thought that the various intrusive and extrusive events occurring in different epochs in the Baul massif are connected to the Depresion de Barquisimeto Lineament. The above lineaments are not clearly defined, simple unilinear structures, but rather they are zones that contain one or more of the aforementioned aligned characteristics. It is believed that they are major fracture zones delimiting major basement blocks along which complex and varied displacements have occurred. Apart from vertical displacements, those recognized lineaments also show strike displacements. Repetitive movement along the proposed lineaments have given rise to unconformities as well as the facial and thickness changes there found. Said lineaments appear to have been active since well before the end of the Paleozoic, through the Mesozoic and Cenozoic right up to the Holocene. The Eastern Maracaibo Lake Lineament is directly related to important known oil fields. As a result these lineaments may well become an initially useful tool in petroleum and gas prospection by means of the search for stratigraphic and structural traps along their length.

DE - DESCRIPTORS: Andes-; Barquisimeto-Depression-Lineament; Caparo-Lineament; Cenozoic-; Colombia-; Cucuta-Depression-Lineament; East-Maracaibo-Lake-Lineament; Eastern-Cordillera; facies-; faults-; folds-; geophysical-surveys; Guyana-Shield; Lake-Maracaibo; lineaments-; Mesozoic-; natural-gas; oil-and-gas-fields; Paleozoic-; petroleum-; petroleum-exploration; South-America; structural-traps; surveys-; tectonics-; thickness-; traps-; Venezuela-; West-Maracaibo-Lake-Lineament

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

DT - DOCUMENT TYPE: Serial

BL - BIB LEVEL: Analytic

MC - MAP COORDINATES: LAT: N080000; N090000; LONG: W0700000; W0710000.

IL - ILLUSTRATION: Refs: 20; geol. sketch maps.

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

IS - ISSN: 0072-0992

CO - CODEN: GECBA7

AN - ACCESSION NUMBER: 2003-027091

UD - UPDATE CODE: 200309

Registro 433 de 5614 - GeoRef : 2002-2004/12

TI - TITLE: Lineamientos Muzo, Tunja y Paipa en los Departamentos de Boyaca y Casanare, Colombia

Translated Title: The Muzo, Tunja and Paipa lineaments in the Boyaca and Casanare departments, Colombia.

AU - AUTHORS: Ujueta-L-Guillermo

AF - AUTHOR AFFILIATION: Universidad Nacional de Colombia, Departamento de Geociencias, Bogota, Colombia

SO - SOURCE: Geologia Colombiana. 18; Pages 65-73. 1993.

PB - PUBLISHER: Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Geociencias. Bogota, Colombia. 1993.

CP - COUNTRY OF PUBLICATION: Colombia

PY - PUBLICATION YEAR: 1993

LA - LANGUAGE: Spanish

LS - LANGUAGE OF SUMMARY: English

AB - ABSTRACT: The Muzo, Tunja and Paipa lineaments are important Northwest-Southeast trending tectonic elements found in the Bogota-Sogamoso sector of the Eastern Cordillera of Colombia. They are superficially expressed as notorious alignments of topographic lows that exert a strong influence on drainage as well as being directly related to the appearance and delimitation of the high plains found in this part of the cordillera. The best evidence towards the structural control exerted by these NW-SE structures is the rupture and displacement of those structures parallel to the general trend of the cordillera. Examples of these are the truncation or distortion of individual folds or faults or the displacement of groups of folds and faults. Several volcanic centers, lesser intrusions and high temperature hot springs are found along the proposed lineaments. In connection with the former, at aligned intervals are found mainly emerald occurrences as well as non-economic copper, iron, fluoride, lead and zinc deposits. Their occurrence is such that they may be directly related to the circulation of hydrothermal fluids that gave rise to such deposits. The nature of these reasonably parallel lineaments regularly spaced every 40 to 50 km, repeatedly reactivated and with lengths of hundreds of kilometers such as those here considered is important in the tectonic history not only of the Eastern Cordillera but also of the Subandean basin of the Llanos Orientales and even of the Guayanan Craton itself.