Boletin de Geologia最新文献

{"title":"Petrografía, geoquímica y geocronología U/Pb en circones de rocas ígneas y metamórficas a lo largo del Río Cuiarí en el sur del Departamento de Guainía, Colombia","authors":"Amed Bonilla, Thomas Cramer, Marc Poujol, H. Cano, J. Franco, Zeze Amaya","doi":"10.18273/REVBOL.V41N1-2019003","DOIUrl":"https://doi.org/10.18273/REVBOL.V41N1-2019003","url":null,"abstract":"espanolPara avanzar en la comprension de la Provincia Geocronologica Rio Negro-Juruena (1,55-1,8 Ga) del Craton Amazonico en el suroriente colombiano se analizaron rocas metamorficas, igneas y meta-sedimentarias aflorantes alrededor del Rio Cuiari en el sur del Departamento de Guainia, zona limitrofe Colombia-Brasil. Con base en observaciones de campo, analisis mineralogicos, geoquimicos y edades LA-ICP-MS U/Pb en circones se identifico en el area un basamento Estateriano (formando aqui el Complejo Mitu) compuesto de granitoides tipo S, principalmente monzograniticos y en menor proporcion cuarzo-monzoniticos a granodioriticos, calcoalcalinos, meta a peraluminosos, con caracteristicas de granitos sin-colisionales a pos-orogenicos con edades U/ Pb de cristalizacion entre 1760 y 1800 Ma. Adicionalmente afloran intrusivos graniticos mas alcalinos de textura porfiritica con fenocristales ovoides de feldespato potasico y una edad de cristalizacion U/Pb en circones de ~1750 Ma (probablemente asociado a la Suite Intrusiva Tiquie definida en Brasil). Sobre este basamento Estateriano fue depositada una secuencia sedimentaria (que pertenece al Grupo Tunui) entre 1750 y 1600 Ma descritas como metarenitas y cuarcitas con turmalina, probablemente como miembro superior del Grupo Tunui que fue afectado por metasomatismo relacionado con la intrusion de un granito porfiritico de dos micas con una edad de cristalizacion entre 1550 y 1600 Ma (asociado a la Suite Intrusiva Rio Icana). Circones heredados con edades del Complejo Mitu ~1780 Ma en este intrusivo sugieren un origen del magma por fusion parcial de material cratonico en presencia de suficiente agua y presion no demasiada alta para una temperatura de fusion relativamente baja que permitieron formar un magma enriquecido en fluidos y elementos incompatibles como Rb y K. Paragneises con edades en circones detriticos mas jovenes entre 1000-1800 Ma, cierran el ciclon geologico precambrico reconocible en esta area de Colombia con un potencial mineralizante y desarrollo tectonico y paleogeografico todavia por determinar en detalleorms the Mitu Complex. EnglishIn order to archive a better understanding of the Rio Negro-Juruena Geochronological Province (1.55-1.8 Ga) of the Amazonian Craton in SE-Colombia, we performed analyses of metamorphic, igneous and metasedimentary rocks outcropping in vicinity of the Cuiari-River in the south of Guainia Department, near the Brazilian border. Based on field observations, mineralogical, geochemical and U/Pb LA-ICP-MS analysis in zircons, we could identify in the study area a Statherian basement which fS-type granitoides, mainly monzogranitic to a lesser amount of quartz-monzodioritic to granodioritic, with calc-alkalic meta to peraluminosos, syncollisional to post orogenic characteristics and with U/Pb crystallization ages between 1760 to 1800 Ma. Additionally, in the study area more alkalic granitic intrusions with ovoidal K-feldspar phenocrysts forming a porphyritic texture ou","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47835828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Campo Volcánico Monogenético Villamaría-Termales, Cordillera Central, Andes colombianos (Parte II): Características composicionales","authors":"Pablo Osorio, Luis Alvaro Botero-Gómez, Hugo Murcia, C. Borrero, Jeny Alejandra Grajales","doi":"10.18273/REVBOL.V40N3-2018006","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N3-2018006","url":null,"abstract":"The Villamaría-Termales Monogenetic Volcanic Field (VTMVF) consists of at least 14 monogenetic volcanoes that are aligned along the Villamaria-Termales Fault System (VTFS; western flank of the Central Cordillera of Colombia). Petrography and geochemical data allowed to define the compositional features of this volcanic field. The petrographic analysis shows that: pyroxene + amphibole + plagioclase, is the common mineral association for all the volcanoes from the VTMVF. The presence of other mineral phases such as: olivine and quartz in some volcanoes established the only difference between the whole field. Geochemical data shows a great compositional variety in the VTMVF represented by the SiO2 content between ~56 and ~69 wt.%, and an adakitic signature represented by low Y content (10 19 ppm) and HREE values as well as high Sr content (>518 ppm). Comparing these characteristics with those from the polygenetic Nevado del Ruiz Volcanic Complex (NRVC), it is possible to suggest a genetic relationship between both and a likely common magmatic reservoir.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45767984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Los volcanes de Colombia y su representación en diversos contextos","authors":"John J. Sánchez, Luisa M. Calvache","doi":"10.18273/REVBOL.V40N3-2018007","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N3-2018007","url":null,"abstract":"There are an important number of volcanoes in Colombia, which, for centuries, have been viewed as symbols but not as hazards, and this has demonstrated to be troublesome in times of crisis. Observations of different ways of representation of the concept of volcano in Colombia are reported. More than 228 observations were compiled during field outings and by means of systematic queries using search engines and electronic mail during the period 2010-2017, keeping graphic evidence of all cases. It was found that 19 volcanoes (both active and inactive) have been represented in 28 contexts in 71 localities mainly surrounding the influence areas of volcanism. Representations may have variable spatial character: local, regional or national; or may exhibit varying temporal nature: ephemeral, such as the cases of murals, commercial signs and logos, or last for centuries because they are included in the symbols of administrative units as in the case of coats of arms of municipalities and provinces. Representations are important because they reflect sense of belonging of the communities towards their environment, imprint the concept of volcano in the collective imagination, and might influence the perception of volcanic hazards and the decision-making process during times of volcanic crisis.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":"1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41916624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experiencias de socialización acerca de amenazas volcánicas en instituciones educativas del municipio de Cumbal (Nariño, Colombia)","authors":"Hermes G. Cuaical, Geólogo Independiente., John J. Sánchez","doi":"10.18273/revbol.v40n3-2018008","DOIUrl":"https://doi.org/10.18273/revbol.v40n3-2018008","url":null,"abstract":"With the aim of providing direct information about volcanoes and their hazards, several activities to promote awareness were accomplished targeting children in eight public schools ascribed to the Municipality of Cumbal (State of Nariño in southwestern Colombia). Activities included talks, practical exercises and outings, and used audiovisual aids with information on various volcanoes around the world, such as photographs of volcanic deposits from the region and scientific products like geologic maps and stratigraphic columns. Additionally, an educational video was produced by one of the authors (HGC, who was born in the Municipality of Cumbal and belongs to the Pastos ethnic group) in which a number of aspects of volcano science are explained using simple terms that were accessible to the audiences. The scientific knowledge was of interest to the easy-going students and their instructors despite the strong ethnic-pedagogical tradition in these institutions where instructors teach that everything around is sacred and mystical. The need to widen the coverage is acknowledged as well as the importance of keeping continuity of the activities and strengthening basic concepts to improve both assimilation of knowledge on volcanoes and their hazards and the impact from the activities of various institutions that work toward mitigating the effects of volcanic activity.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46088353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morfometría de las estructuras asociadas a la Cadena Volcánica de Los Coconucos (CVLC), Colombia","authors":"Wveimar Samacá, John J. Sánchez","doi":"10.18273/REVBOL.V40N3-2018001","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N3-2018001","url":null,"abstract":"The Coconucos Volcanic Chain (CVLC-from its acronym in Spanish) is made up by 14 volcanic centers (nine composite volcanoes and five monogenetic volcanoes) oriented along the Coconucos Lineament. Two more centers, maar-type volcanoes, are also located to the SW, in the vicinity of the CVLC. To study the development of these volcanic centers, the ellipticity ( e i ) and irregularity ( i i ) morphometric parameters as well as the base-to-height H/W B for composite volcanoes and the height-of-cone to width-of-cone H co /W co ratios for monogenetic centers, were evaluated. The values for morphometric parameters and dimensional ratios vary as follows: 1.27< e i <3.24; 1.12< i i <1.53; 0.04< H/W B <0.24 and 0.02< H co /W co <0.34. Graphs of morphometric parameters ordered according to the spatial position of the volcanic centers allowed identification of partial tendencies in the evolution of composite volcanoes and patterns in the state of preservation for monogenetic centers: e i increases to the SE; i i decreases to the SE; H/W B increases to the SE and H co /W co increases to the NE. Together, these values and patterns suggest not only variability of endogenous and exogenous processes that affect the shapes of volcanoes, but also possible cycles of constructive activity and affectation of morphology and morphometry of the volcanic structures.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45705125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morfometría, estratigrafía, petrografía y geoquímica del cono de escoria El Morro, municipio La Argentina(Huila, Colombia)","authors":"L. Rodríguez, John J. Sánchez","doi":"10.18273/REVBOL.V40N3-2018003","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N3-2018003","url":null,"abstract":"This work is a contribution to the geological knowledge of El Morro eruptive center (CEM), located in the State of Huila (Colombia), by means of the morphometric analysis of the edifice, stratigraphic survey of pyroclastic deposits, and petrographic and geochemical analysis of juvenile clasts. The pyroclastic deposits were characterized in terms of the geometry of the layers, textural and granulometric variations, mineralogy, and whole-rock chemistry. The CEM is a simple and well-preserved scoria cone, and thus it is considered young. It is a mafic eruptive center, composed by pyroclastic deposits, grouped in three distinguishable accumulation packages at the outcrop scale by their normal-to-reverse variable grading. The mostly juvenile clasts that make up the stratigraphic packages vary in size between ash and bomb. The petrography and geochemistry of the CEM clasts indicate the emission of a basaltic magma. From the morphometric relationships and the discrimination diagrams for the geotectonic environment, it was concluded that the fragments analyzed suggest affinity with continental arc basalts and their formation environment is associated to subduction.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45950456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogénesis y condiciones de cristalización del domo intracratérico del volcán Cerro Bravo, Colombia","authors":"C. Pinzón, J. F. Echeverri, Hugo Murcia, Dayana Schonwalder-Ángel","doi":"10.18273/revbol.v40n3-2018004","DOIUrl":"https://doi.org/10.18273/revbol.v40n3-2018004","url":null,"abstract":"Cerro Bravo is a composite volcano located in the Central Cordillera of Colombia. Throughout its 50 ka of evolution, this volcano has been characterised by having successive explosive to effusive phases. At present, the crater hosts a dome that represents the last eruptive phase of the last eruption. The dome has a typical mineralogy of andesite-dacite rocks with plagioclase, amphibole and pyroxene crystals. The amphibole composition allow us to constrain the melt crystallisation conditions at 1 to 3.5 kba, 800 to 950°C, -5.3 to -6.8 fO2, and 5.1 to 6.8 H2O wt.%, while the piroxene composition at 914 ±97°C y 18,5 ±9,2 Kba. Based on these results and the mineralogical configuration, it is possible to establish a crystallisation history as follows: Augite and enstatite were the first formed minerals (>20 – 30 km). After that, the magma ascended up to a magma chamber located between 4.6 and 13.2 km from the surface where the amphibole crystallisation started (pargasite at the base of the chamber and edenite and magnesiohornblende at the top). The drop in temperature and pressure also promoted the crystallisation of labradorite that transitionally changed to andesine. Plagioclase microlites in the groundmass are evidence of the last crystallisation phase close the surface, as a result of magmatic decompression. This study shows the crystalisation conditions that represent the last eruptive phase of the last eruption of the Cerro Bravo volcano.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43852725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estratigrafía del cráter y morfología del volcán Cerro Machín, Colombia","authors":"Daniel Alberto Piedrahita, C. Aguilar-Casallas, E. Arango-Palacio, Hugo Murcia, Johana Gómez-Arango","doi":"10.18273/REVBOL.V40N3-2018002","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N3-2018002","url":null,"abstract":"The Cerro Machín Volcano (CMV) is located on the eastern flank of the Central Cordillera of Colombia, 17 km west of the city of Ibagué (Tolima). The CMV, a dacitic Holocene volcano, has evidence of multiple considerable eruptions (VEI 5). The inner walls of the crater display a sequence of dilute pyroclastic density currents (PDC) deposits, which contain characteristics of basal surge deposits. The presence of accidental lithics indicates that the basement of the volcano was involved in the magmatic fragmentation process. It is, thus possible to suggest that water-magma interaction played an important role in the dynamics of the last eruptive event, which formed the deposits that molded the crater. On the other hand, a morphological analysis revealed that the crater is 2.4 km in diameter, has an opening which faces the southwestern sector, and carries a dome of 490 m in height. Thus, it is interpreted that the growing dome destroyed the crater during its emplacement. Although the CMV is undoubtedly a polygenetic volcano (six eruptions in the last 5000 years), the sedimentological and morphological characteristics of the crater deposits suggest a monogenetic tuff cone structure. In conclusion, the CMV should be defined as a “composite volcano with tuff cone morphology”.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45070381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Campo Volcánico Monogenético Villamaría-Termales, Cordillera Central, Andes colombianos (Parte I): Características morfológicas y relaciones temporales","authors":"Luis Alvaro Botero-Gómez, Pablo Osorio, Hugo Murcia, C. Borrero, Jeny Alejandra Grajales","doi":"10.18273/REVBOL.V40N3-2018005","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N3-2018005","url":null,"abstract":"The Villamaría-Termales Monogenetic Volcanic Field (VTMVF) is located in the middle of the Central Cordillera of Colombia. It is part of the San Diego Cerro Machín Volcano Tectonic Province (SCVTP), and is related to the Nevado del Ruiz Volcanic Complex (NRVC). The VTMVF is composed of at least 14 monogenetic volcanoes; 12 of them are conical and subconical (domes), one is massif (dome), and one is irregular (lava flow). Based on the morphometric and geomorphological analysis reported in this study, we define the VTMVF as a volcanic field affected by a variety of geomorphological and glacial processes. This field occupies an area of 114.5 km2, where the Villamaría-Termales fault system controlled the volcanic dispersion. These volcanic centers have an age range between 1.8 Ma and <38,000 years (Calabrian-Late Pleistocene). The morphometric analysis as volume and separation and grouping indexes allowed us to define the spatial relationship (i.e. distance between the volcanoes and their geoforms) between the volcanic centers that make up the VTMVF.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46674591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Caracterización preliminar de las arenas asfálticas de Picacho, municipio de Pesca (Boyacá, Colombia)","authors":"O. Gómez-Rojas, Á. G. Borrego, Carlos Perea-Solano, Oswaldo Alfonso Sánchez-Morales, Hither Fernando Flórez-Molano","doi":"10.18273/REVBOL.V40N2-2018005","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N2-2018005","url":null,"abstract":"espanolEn Colombia las arenas asfalticas las explotan para la pavimentacion de vias terciarias, un ejemplo de esto son las areniscas asfalticas de la Formacion Picacho, ubicadas en el municipio de Pesca, Boyaca. Este estudio tiene como objetivo una caracterizacion de las arenas asfalticas con el fin de tener una informacion preliminar sobre su variacion en composicion global entre dos frentes de explotacion (minas La Emilia y Santa Teresa) con vistas a su posible potencial como fuente de hidrocarburos no convencionales. Los metodos comprenden analisis elementales, fisico mecanico, SARA y pirolisis. Los resultados determinan que la unidad esta compuesta por areniscas siliceas. Los porcentajes de azufre son bajos en casi todas las muestras, excepto una que alcanza 5%, la gravedad API determina que los crudos presentan un valor de 22,4 y 9,2 indicando que son crudos medios y extra pesados, las fracciones de crudo reflejan una mayor proporcion de resinas y asfaltenos, la pirolisis indica un elevado contenido en volatiles que destila a temperaturas por debajo de 500oC. EnglishThe tar sands are mined in Colombia for paving the local roads. An example of this use is the tar sands of the Picacho Formation, located in the municipality of Pesca, Boyaca. The objective of this study is providing a preliminary bulk characterization to evaluate this resource as a possible source of unconventional hydrocarbons in this area. The study is limited to two fronts of exploitation named the La Emilia and Santa Teresa mines. The methods used comprise elemental analysis, physico-mechanical test, SARA and pyrolysis. The results determine that the unit is composed of siliceous sandstones. The percentages of sulfur are low in most of the samples, except one that reaches 5%, the API gravity between 22.4 and 9.2 indicates that they range between medium and extra heavy crude, the oil fractional composition reflects a higher proportion of resins and asphaltenes, the pyrolysis indicates a high volatile content that completely distill at temperatures below 500oC.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44841916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}