Cadernos do Laboratorio Xeoloxico de Laxe最新文献

{"title":"Variabilidad en la micro-dosimetría beta del sedimento como principal causa de dispersión en la datación OSL de los depósitos fluviales costeros fini-pleistocenos conservados en la Cuenca del Río Mero (A Coruña, Galicia, España)","authors":"Carlos Arce-Chamorro, J. Sanjurjo-Sánchez","doi":"10.17979/CADLAXE.2020.42.0.7308","DOIUrl":"https://doi.org/10.17979/CADLAXE.2020.42.0.7308","url":null,"abstract":"En este trabajo se han estudiado las dosis equivalentes (De) obtenidas de la señal OSL del cuarzo, para depósitos fluviales del Pleistoceno Superior de la cuenca del río Mero (A Coruña, Galicia, España) y conservados en el margen costero de la Ría de A Coruña (NO Península Ibérica). Estas De muestran distribuciones con una dispersión mayor a la esperada, obteniéndose porcentajes de sobre-dispersión elevados (OD>20%). Estos valores suelen asociarse al blanqueamiento incompleto de la señal OSL, debido al transporte de los granos de cuarzo en un medio turbio, debido una caga finos en supresión. No obstante, los gráficos y test de bondad de ajuste describen distribuciones normales, simétricas y centradas en la media. Tampoco indican evidencias de dos o más poblaciones de alícuotas conformadas por dos clases de granos de cuarzo agrupadas: (i) un grupo donde la señal de los granos ha sido bien blanqueada antes del último episodio de deposición y enterramiento y (ii) otro grupo que muestran señal heredada (residual). Sin embargo, los experimentos de Dose Recovery realizados indican que la dispersión se debe a factores extrínsecos y no intrínsecos al tipo de cuarzo estudiado. Por ello, se han analizado las concentraciones de radioisótopos en las muestras y la concentración de potasio en diferentes granulometrías, para estimar si el origen de la sobre-dispersión es la micro-dosimetria causada por el 40K del potasio, dada las bajas tasas de radiación y dosis anual medidas en las muestras. Los resultados obtenidos muestran que esta es la causa más probable de la dispersión, no encontrándose evidencias de blanqueamiento parcial.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77383139","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":"Geotourism from Fuente de Cibeles of Madrid. History, Building Stones and Quarries","authors":"D. Freire-Lista","doi":"10.17979/CADLAXE.2020.42.0.7286","DOIUrl":"https://doi.org/10.17979/CADLAXE.2020.42.0.7286","url":null,"abstract":"Fuente de Cibeles of Madrid (Spain) represents Cybele goddess sitting on a carriage drawn by two lions. This sculptural set was carved in Montesclaros (Toledo-Spain) marble between 1777 and 1782. The sculptural set has experienced some modifications throughout its history. Two zoomorphic water-spouts carved in Colmenar de Oreja limestone, one in the shape of a dragon and another one in the shape of a bear, were installed in 1798. In 1895, the fountain changed of location, and two putti of Carrara marble were installed on the back of the fountain, expanding the rocky surface promontory on which the sculptural set stands. Two tiered basins made of granite were added in 1968, when the fountain acquired its current form.A geotouristic route was created based on Fuente de Cibeles and its main building stone, Montesclaros marble. An exhaustive description of the fountain was made, and its construction history was reviewed to elaborate the route. In this way, alternatives that diversify the conventional tourist options of the city of Madrid are presented. In addition, scientific data on historical quarries and the marble that forms part of the emblematic fountain is provided.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84871007","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":"Palaeoenvironmental data from fluvial deposits associated to ancient fishing weirs in the Miño river, NW Iberia","authors":"J. Sanjurjo-Sánchez, Carlos Arce-Chamorro, V. Barrientos, Ana Goy-Diz","doi":"10.17979/CADLAXE.2020.42.0.7284","DOIUrl":"https://doi.org/10.17979/CADLAXE.2020.42.0.7284","url":null,"abstract":"Fluvial sediments provide environmental records of the Quaternary. In some cases, fluvial deposits are caused by anthropogenic processes that cause changes in the water regime of some river stretches. This is the case of dams. It has been reported that some dams or partial damming systems existed in the past, at least from some thousands of years ago. Such dams were used for fishing purposes and are referred as fishing weirs. In a recently published work it has been demonstrated that a fluvial thick deposit was caused by a damming system in a river of NW Iberia (River Miño, Pontevedra). Optically stimulated luminescence (OSL) provided the burial age of such fluvial deposit, showing a 1300-year-old fluvial record. The sedimentation rates of the record did not match with known climate fluctuations in the area. In this work, the sedimentation phases of such record are identified, and the detrital and organic matter content is studied to assess any change occurred in the environmental and fluvial conditions during the deposition period of the record that ranges from 814±134 to 1837±11 AD.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76179631","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":"Are corestones due to weathering and/or tectonism? Problems and suggestions","authors":"C. Twidale, J. R. Vidal Romaní","doi":"10.17979/CADLAXE.2020.42.0.7268","DOIUrl":"https://doi.org/10.17979/CADLAXE.2020.42.0.7268","url":null,"abstract":"Many of the so-called corestones have been developed from rocky blocks that have been apparently affected by subsurface physicochemical weathering that results in lamination, granulation, and eventually a puggy or stiff clay. The truth is that weathering takes advantage of a previous deformation structure and does not create it by weathering.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80360092","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 derrubios estratificados holocenos de Praón (Picos de Europa, Montañas Cantábricas)","authors":"J. Ruiz-Fernández, C. García-Hernández, S. Fernández","doi":"10.17979/cadlaxe.2019.41.0.5811","DOIUrl":"https://doi.org/10.17979/cadlaxe.2019.41.0.5811","url":null,"abstract":"En este artículo se estudian los derrubios estratificados y cementados presentes en Praón, un sector de la baja montaña de los Picos de Europa. La realización de trabajo de campo sistemático ha permitido establecer el contexto geomorfológico en el que están insertos los derrubios estudiados, caracterizándolos desde el punto de vista sedimentológico. Se han obtenido dos edades 14C en restos de gasterópodos insertos a 4 metros (10.775 ± 325 años cal BP) y a 1,7 metros (5.175 ± 135 años cal BP) de profundidad, infiriendo las condiciones de precipitación del cemento carbonatado a partir de la realización de análisis isotópicos. Estas condiciones habrían sido más frías para la muestra más antigua y mucho más cálidas para la más reciente. Los resultados de este trabajo evidencian que, derrubios estratificados como los estudiados, los cuales son abundantes en el área de los Picos de Europa, podrían haberse originado en condiciones climáticas diversas y no necesariamente de frío extremo, ni exclusivas de ambientes periglaciares sensu stricto, no teniendo tampoco por qué corresponderse, desde el punto cronológico, con el Tardiglaciar (en cronologías de 14 a 10 ka), el periodo frío al que tradicionalmente han sido adscritos de forma relativa en las Montañas Cantábricas.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74927664","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":"La importancia de los tanques naturales (mega gnammas) en la preservación de fósiles de la megafauna cuaternaria en el Noreste de Brasil","authors":"Felipe Rodrigues Waldherr, Hermínio Ismael De Araújo-Júnior, Sérgio Wilians De Oliveira Rodrigues, Celso Lira Ximenes","doi":"10.17979/cadlaxe.2019.41.1.5819","DOIUrl":"https://doi.org/10.17979/cadlaxe.2019.41.1.5819","url":null,"abstract":"Los tanques (mega gnammas) de origen natural excavados en roca constituyen formas de tamaño medio muy frecuentes en los relieves graníticos del Noreste de Brasil. El estudio de los sedimentos acumulados en el interior de esos tanques naturales se ha convertido en una fuente de datos de gran interés para el conocimiento de la paleontología cuaternaria de Brasil. Este tipo de cavidades habituales en zonas de sustrato granítico, una vez expuestas en superficie han actuado como depocentros locales para los flujos de agua y sus sedimentos asociados, a veces fosilíferos, lo que ha convertido estas concavidades en auténticas tanatocenosis. El estudio sistemático de las acumulaciones fosilíferas se ha convertido así en la principal herramienta para reconstruir las condiciones paleoambientales y paleoecológicas durante parte del período Cuaternario en la Región Intertropical Brasileña.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87316336","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":"The granite-related, high-tonnage Sn-Li deposit of Argemela, central Portugal","authors":"C. Inverno, Paulo J. V. Ferraz, M. Moreira, Fernanda Guimar˜aes, A. Filipe","doi":"10.17979/CADLAXE.2019.41.0.5823","DOIUrl":"https://doi.org/10.17979/CADLAXE.2019.41.0.5823","url":null,"abstract":"The Argemela Sn-Li quartz vein stockwork, east of the Panasqueira tungsten mine, is hosted in Cambrian slates and greywacke. An underlying Variscan granitic cupola is inferred from spotted slates and albitic microgranite dykes, the last including a thick modified albitic microgranite, enriched in F and Li, exposed some 500 m away, on the hill top. Inferred resources for shallowest deposit portion are 20.1 million tonnes (Mt) at 0.1-0.2% Sn, 0.2% Li and 0.1% (estimate) Rb, but the 650-m vertical-extent of the deposit suggests a resource of >200 Mt (with identical grades). The hydrothermal paragenetic sequence is amblygonite-montebrasite (mostly montebrasite) (Stage I)–quartz I-II–cassiterite (with columbite-tantalite inclusions)─arsenopyrite I─carbonate I-white mica I ─chlorite I–fluorite–apatite–rutile (Stage II)– white mica II–molybdenite– tourmaline– carbonate II-quartz III–arsenopyrite II–sphalerite–stannite–chalcopyrite–pyrite– pyrrhotite-chlorite II (Stage III)–covellite– vivianite–goethite/lepidocrocite (Stage IV). Amblygonite-montebrasite is the main Li carrier; Sn is evenly distributed between cassiterite and stannite; Rb is mostly in white mica (with 0.25-1.23 wt % Rb2O in the hill-top albitic microgranite). Primary aqueous, 1-3 um-wide fluid inclusions in the deposit in quartz I, carbonate I, apatite and cassiterite growth zones yield overall salinities and homogenisation temperatures of 7.2-19.1 wt % NaCl equiv. and 290-360ºC, respectively. The trace concentrations (electronic microprobe analysis) in quartz vein cassiterite reach 1.95 wt % Nb, 0.39 wt % Fe, 0.13 wt % Ti, and low/negligible values of Sb, Zn, As, Ag and Bi showing its granite-hydrothermal affiliation. Fe-poor and Fe-rich sphalerite (lower-intermediate and upper deposit parts) contain 1.0-1.6 and 7.9-9.4 wt % Fe, 64.3-66.0 and 55.9-57.2 wt % Zn, 0.4-0.5 and 0.9-1.1 wt % Cd, respectively. The sphalerite-stannite geothermometer yields temperatures of 245-297ºC. Following higher temperature amblygonite-montebrasite deposition (Stage I), hydrothermal fluids (aCl-=0.25 m), related to the hidden granitic cupola, at a mean pressure-corrected (50 MPa) temperature of 350ºC, were responsible for Stage II minerals deposition. Calculated cassiterite deposition from Sn chloride complexes occurred likewise, from probable magmatic-hydrothermal fluids, at fO2 = 10-34 -10-32 atm and pH=3.5-4. Cassiterite deposition mechanisms were oxidation, mixing, neutralisation, possible aCl- increase, and cooling. Later Fe-poor sphalerite (+kesterite/ferrokesterite) and Fe-rich sphalerite (+stannite) deposited at higher and lower fS2, respectively, the latter probably at a higher fO2 (Stage III). The uniqueness of Argemela system with abundant amblygonite-montebrasite in hydrothermal quartz tin veins may be related to an extreme fractionated F-, Li- and P-rich granitic magma. After the emplacement of the granite/albitic microgranite dykes, an emerging pegmatitic fluid was unable, possibly due to insuf","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90036943","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":"International adaptation of the hydrologic rational method: floods study in the North Portugal region","authors":"A. Vázquez-Rodríguez","doi":"10.17979/cadlaxe.2019.41.0.5810","DOIUrl":"https://doi.org/10.17979/cadlaxe.2019.41.0.5810","url":null,"abstract":"Floods have a big capacity of create great social and economic losses in a short time interval. Spain and other countries have this problem in their territories. These can have different origins, being the rivers overflowing the more common cause. There are different approaches of these phenomena studies, and the modified Témez rational method is the referenced one in Spain, which with the GIS and hydrological simulation programs can create the flooding areas cartography, key information in the floods hazard management. But, is this method only valid for Spain, or is it applicable to other countries? The answer is that its adaptation to other countries is possible, always that the relevant modifications are made.In the Iberian Peninsula, Portugal is a country that has the flooding problem too. Because this country has a similar geological and geographical conditions to the western Spain, and the floods effects are similar in the Portuguese territories, the adaptation to this country it´s relatively simple.The aim of this work is the study of floods dynamics in Portugal, adapting the modified Témez rational method. This method will be applied in the Âncora river, in North Portugal region fluvial system because the geological and geographical conditions are similar to the west of Spain ones.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83351463","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 de la roca soporte de los petroglifos de Campo Lameiro (Pontevedra)","authors":"B. Silva, P. Sanmartín, Beatriz Prieto","doi":"10.17979/cadlaxe.2019.41.0.5821","DOIUrl":"https://doi.org/10.17979/cadlaxe.2019.41.0.5821","url":null,"abstract":"Entre los años 2005-2008 se llevó a cabo un proyecto de investigación para analizar las causas del deterioro de los petroglifos de Campo Lameiro (Pontevedra). La roca soporte de los grabados se caracterizó como un granito de dos micas de grano medio-fino y textura granuda equigranular alotriomorfa. Presenta una intensa fisuración a todos los niveles lo que le confiere una elevada porosidad y gran capacidad de absorción de agua. En campo se observa una densa red de diaclasas, sin embargo un estudio específico reveló que esto no supone riesgo de pérdida masiva de roca que pueda afectar a las superficies que poseen grabados. Los análisis mineralógicos y geoquímicos pusieron de manifiesto que el granito experimentó procesos de hidrólisis y de solubilización-precipitación del hierro, lo que indica que es el agua el principal agente de alteración en el material lítico.","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82686625","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":"Determinación de campos areales de precipitación y evapotranspiración en la margen izquierda de la cuenca del Paraná en territorio de Argentina. I: polígonos de Thiessen y kriging","authors":"Rosana del Carmen Hämmerly, M. París, Antonio Paz González","doi":"10.17979/cadlaxe.2019.41.1.5818","DOIUrl":"https://doi.org/10.17979/cadlaxe.2019.41.1.5818","url":null,"abstract":"La precipitación (P) y la evapotranspiración potencial (ETP) son términos de la ecuación del balance hídrico que se miden en estaciones locales; sin embargo el uso de modelos de estimación de caudal requiere datos de los mismos a escala de cuenca. En este trabajo se presentan los resultados de la estimación de la precipitación y la evapotranspiración, interpolados mediante polígonos de Thiessen y la técnica geoestadística de kriging en aquellas subcuencas de la margen izquierda del Río Paraná, en territorio argentino que disponen de registros de caudal. Se estudiaron doce cuencas ubicadas en las provincias de Misiones, Corrientes y Entre Ríos, y se usaron las series de datos meteorológicas disponibles dentro de las mismas y en su periferia, en un periodo común de tiempo, entre 1970 y 2010. Previa a la obtención de la precipitación media areal se completan los datos mensuales faltantes. A partir de dicha información se pudo ponderar la aportación espacial de cada sitio de medida. Los datos medidos mensuales de precipitación y ETP presentaron dependencia espacial que fue descrita por semivariogramas de tipo lineal y gaussiano, respectivamente. En comparación con los polígonos de Thiessen, el krigeado o kriging ordinario proporciona estimaciones areales inferiores de precipitación en 11 de las 12 cuencas estudiadas, observándose las mayores diferencias en la provincia de Misiones. Se concluye que no se evidencia una mejor estimación de campos de precipitación y de ETP como resultado del incremento de la complejidad del método usado para la obtención de los mismos","PeriodicalId":35856,"journal":{"name":"Cadernos do Laboratorio Xeoloxico de Laxe","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89192092","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}