Estudios Geologicos-Madrid最新文献

{"title":"Nuevo registro de la biota ediacárica en la Arenisca de Jodhpur (Supergrupo de Marwar), Rajasthan occidental, India","authors":"V. S. Parihar","doi":"10.3989/egeol.43590.563","DOIUrl":"https://doi.org/10.3989/egeol.43590.563","url":null,"abstract":"In western Rajasthan, India, the Jodhpur Sandstone of the Marwar Supergroup has yielded a new Ediacaran fossil assemblage comprising macroscopic well-preserved specimens of Aspidella, Hiemalora , large Ediacaran discs, Tirasiana disciformis, Medusinites asteroides, Anfesta -like Ediacaran body fossils and microbial mat structures ( Arumberia banksi, Kinneyia mat structures, wrinkle mat structures and other mat structures). The fossil record allows suggesting a broad correlation with the Fermuse Formation, Newfoundland, South Australia, White Sea of Russia and Norway, and regionally correlated with the Bhander Group of Vindhyan Supergroup and Krol Group of Lesser Himalaya.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"33 1","pages":"108"},"PeriodicalIF":0.7,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76659190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sesgo tafonómico en los datos de distribución de Cloudina en Siberia","authors":"G. Markov, V. Rogov, G. A. Karlova, D. Grazhdankin","doi":"10.3989/egeol.43590.559","DOIUrl":"https://doi.org/10.3989/egeol.43590.559","url":null,"abstract":"Cloudina -morph fossils in Siberia have been traditionally regarded as a taphonomic mode of Anabarites tests inserted one into another under specific hydrodynamic conditions. Clusters of telescoped conical tests are ubiquitous in the Kessyusa Group and coeval strata across Siberia and not all of them can be easily interpreted as a result of simple mechanical stacking. It remains to be confirmed whether any of these clusters actually represents a life association of a Cloudina -morph structure.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"207 1","pages":"104"},"PeriodicalIF":0.7,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74579747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fauna ediacárica del Grupo de Jodhpur (Supergrupo de Marwar) en la ciudad de Jodhpur, al oeste de Rajasthan, India: Implicación para la selección de posibles sitios geopatrimoniales","authors":"S. Mathur, Sudhanshu Sharma, S. K. Singh, S. C. Mathur","doi":"10.3989/egeol.43595.560","DOIUrl":"https://doi.org/10.3989/egeol.43595.560","url":null,"abstract":"The Ediacaran fossil record of the Jodhpur Group in the surroundings of Jodhpur city, western Rajasthan, is revised. Their best exposures are considered as potential Geoheritage sites. A specific protection from quarrying is envisaged.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"657 1","pages":"105"},"PeriodicalIF":0.7,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76276496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisión de la edad del Grupo de Asha en los Urales meridionales","authors":"A. Kolesnikov, N. I. Bobkov","doi":"10.3989/egeol.43590.558","DOIUrl":"https://doi.org/10.3989/egeol.43590.558","url":null,"abstract":"The Asha Group of the South Urals, initially erected by Albert Olli as Palaeozoic sedimentary complex, more than half a century ago was considered as a key section for the Vendian (Ediacaran) of the western slope of the South Urals. However, the ca. 1700 m-thick terrigenous sedimentary sequence is characterised by unusual low biodiversity of Ediacaran macrofossils, which might be explained by relatively young age of the Asha Group and possible mass extinction event in the end of Ediacaran Period. The relatively young age was confirmed by the U-Pb zircon date of 547.6±3.8 Ma obtained from the tuff in the lower part of the Basa Formation as well as finding of ichnospecies Didymaulichnus tirasensis in the upper part of Zigan formation. However, in 2018 it has been documented there the mass appearing of D. tirasensis in the lowermost part of the Basa Formation. Therefore, the Vendian (Ediacaran) age of the Asha Group of the South Urals can be revisited in favour to terminal Ediacaran- Cambrian or even early Cambrian.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"14 1","pages":"103"},"PeriodicalIF":0.7,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89474226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluación de la Formación ediacárica de Doushantuo: mejora de la correlación estratigráfica de las pizarras negras de Doushantuo superior a partir del contenido en mercurio","authors":"M. Nolan, S. Xiao, Benjamin C Gill, D. Jones, C. Zhou","doi":"10.3989/egeol.43595.562","DOIUrl":"https://doi.org/10.3989/egeol.43595.562","url":null,"abstract":"Mercury enrichments in the black shale unit of the Ediacaran Doushantuo Formation are, likely the result of volcanic input or anoxia-driven mercury deposition. If the Hg enrichments are volcanic in origin, or are due to synchronous regional anoxia, then the patterns of Hg enrichment are consistent with the conventional correlation of these units, with the tripartite units equivalent to Member IV black shales. Additionally comparing redox proxy data from the intervals of Hg enrichment could indicate if the enrichments are due to comparable changes in redox conditions, or increased Hg input under differing redox conditions, consistent with volcanic input.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"10 1","pages":"107"},"PeriodicalIF":0.7,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75451073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"El sector más occidental de la Formación de Los Navalucillos, Cámbrico inferior: microbialitas en yacimientos mareales de la Zona Centroibérica, Monte de Toledo, España","authors":"S. Menéndez, M. Rodríguez-Martínez, E. Moreno-Eiris, A. Perejón","doi":"10.3989/egeol.43589.561","DOIUrl":"https://doi.org/10.3989/egeol.43589.561","url":null,"abstract":"In the Central Iberian Zone of the Iberian Massif, the Los Navalucillos Formation, interpreted as tidal and shallow-marine carbonate deposits, contains a significant archaeocyathan faunal assemblage. Two new characteristic exposures are described here from the westernmost outcrops of the formation, close to La Nava de Ricomalillo area: (i) La Estrella, where the rocks are strongly affected by contact metamorphism due to the nearby plutonic complex; and (ii) the Finca Higueruela succession, without calcimicrobial-archaeocyathan boundstones, although different microbialites as stromatolites and oncolites are conspicuous.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"17 1","pages":"106"},"PeriodicalIF":0.7,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88886060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reevaluación de la tafonomía de las asociaciones conservadas in situ de Cloudina en la Formación de Tagatiya Guazu, Grupo ediacárico de Itapucumi, Paraguay","authors":"L. Inglez, L. Warren, J. Okubo, M. G. Simões","doi":"10.3989/egeol.43595.555","DOIUrl":"https://doi.org/10.3989/egeol.43595.555","url":null,"abstract":"The fossil assemblage from the Tagatiya Guazu Formation (Ediacaran Itapucumi Group, Paraguay) represents a unique opportunity to investigate paleoecological parameters and contribute with taxonomic information regarding Cloudina associations in SW Gondwana.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"16 1","pages":"100"},"PeriodicalIF":0.7,"publicationDate":"2019-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75123495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisión sistemática del trilobite oryctocefálido Protoryctocephalus arcticus Geyer & Peel, 2011 del Cámbrico inferior (Piso 4) de Balang, China meridional","authors":"J. Esteve, Y. Zhao, X. Yang","doi":"10.3989/egeol.43586.553","DOIUrl":"https://doi.org/10.3989/egeol.43586.553","url":null,"abstract":"The oryctocephalid trilobites from the traditional ‘lower-middle Cambrian’ represent key tools for international correlation. The trilobite zones in South China around the Cambrian Series 2-Miaolingian are made using oryctocephalids. One of the trilobite zones suggested is based on Protoryctocephalus arcticus. Protoryctocephalus from the Balang area in South China was described as Protoryctocephalus wuxunensis , also from the Cambrian Series 2 of South China. However, Protoryctocephalus from Balang shows different morphological features such as different glabellar shape, presence of a transglabellar S1 and more segments in the trunk. These features match with Protoryctocephalus arcticus from the Cambrian Series 2 of Greenland.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"70 1","pages":"098"},"PeriodicalIF":0.7,"publicationDate":"2019-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73989544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WHEN LIFE GOT HARD: AN ENVIRONMENTAL DRIVER FOR METAZOAN BIOMINERALIZATION","authors":"A. J. Kaufman, Les Kriesfeld, P. Vickers-Rich, G. Narbonne","doi":"10.1130/abs/2019am-336386","DOIUrl":"https://doi.org/10.1130/abs/2019am-336386","url":null,"abstract":"espanolLa repentina aparicion de metazoos biomineralizados en las facies calcareas del Miembro de Pockenbank (Namibia) parece reflejar un rapido cambio en el estado redox, la concentracion de calcio y la alcalinidad del oceano. La combinacion de una importante innovacion biologica con el final de una profunda excursion de isotopos de carbono respalda la idea de que la anomalia Shuram fue un fenomeno tectonico y oceanografico, en contraposicion a una “conspiracion” diagenetica mundial. La concordancia temporal de estos profundos acontecimientos, tal como se conservan en los estratos de Namibia meridional puede considerarse, por tanto, como marcadores geologicos excepcionales para la base del Ediacarico terminal. EnglishThe sudden appearance of biomineralized metazoans in limestone facies of the Pockenbank Member (Namibia) appears to reflect a rapid change of redox state, calcium concentration and alkalinity of the ocean. The coupling of a major biological innovation with the end of a profound carbon isotope excursion supports the view that the Shuram was a tectonic and oceanographic phenomenon, as opposed to a global diagenetic conspiracy. The temporal concordance of these profound events as preserved in strata from southern Namibia may thus be considered as exceptional geological markers for the base of the terminal Ediacaran.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"19 1","pages":"10"},"PeriodicalIF":0.7,"publicationDate":"2019-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80318826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The large eruption 4.2 ka cal BP in Cerro Blanco, Central Volcanic Zone, Andes: Insights to the Holocene eruptive deposits in the southern Puna and adjacent regions","authors":"J. Fernández-Turiel, F. Perez‐Torrado, A. Rodríguez-González, J. Saavedra, J. Carracedo, M. Rejas, A. Lobo, M. Osterrieth, J. Carrizo, G. Esteban, J. Gallardo, N. Ratto","doi":"10.13039/501100007757","DOIUrl":"https://doi.org/10.13039/501100007757","url":null,"abstract":"espanolLa erupcion del Complejo Volcanico Cerro Blanco en el sur de la Puna, noroeste de Argentina (4410–4150 a BP) se investigo para obtener nueva informacion sobre estratigrafia, geomorfologia, volcanologia fisica, dataciones por radiocarbono, petrografia y geoquimica. La caracterizacion de los productos en relacion a la evolucion de la caldera de Cerro Blanco permitio estimar la distribucion de los depositos de ceniza de la fase paroxismica Plineana de la erupcion. Estos novedosos resultados evidencian una gran erupcion explosiva riolitica que genero depositos cineriticos en un area de aproximadamente 500.000 km2, acumulando > 100 km3 de tefra (volumen total). Este ultimo valor supera el umbral inferior del Indice de Explosividad Volcanica (IEV) de 7. Los depositos de caida de ceniza cubrieron la region, llegando a mas de 400 km desde el Complejo Volcanico de Cerro Blanco, y los potentes depositos de flujos piroclasticos rellenaron los valles vecinos alcanzando una distancia de 35 km. Esta erupcion es la mas grande documentada durante los ultimos cinco milenios en la Zona Volcanica Central de los Andes y es probablemente una de las mayores erupciones explosivas holocenas del mundo. Ademas, se han identificado otras dos erupciones rioliticas en la region procedentes de otros dos centros eruptivos: una durante el Holoceno temprano y otra en el Holoceno tardio. La identificacion y caracterizacion de estos grandes eventos volcanicos proporcionan nuevas guias para los registros geologicos y arqueologicos regionales del Holoceno, siendo marcadores cronostratigraficos de aplicacion a una extensa area geografica de America del Sur. EnglishThe eruption of the Cerro Blanco Volcanic Complex, in the southern Puna, NW Argentina dated at 4410–4150 a cal BP, was investigated to produce new information on stratigraphy, geomorphology, physical volcanology, radiocarbon dating, petrography, and geochemistry. Identification of pre–, syn–, and post–caldera products allowed us to estimate the distribution of the Plinian fallout during the paroxysmal syn–caldera phase of the eruption. The new results provide evidence for a major rhyolitic explosive eruption that spread volcanic deposits over an area of ~500,000 km2, accumulating > 100 km3 of tephra (bulk volume). This last value exceeds the lower threshold of Volcanic Explosive Index (VEI) of 7. Ash-fall deposits mantled the region at distances > 400 km from source and thick pyroclastic-flow deposits filled neighbouring valleys up to 35 km away. This eruption is the largest documented during the past five millennia in the Central Volcanic Zone of the Andes, and is probably one of the largest Holocene explosive eruptions in the world. We have also identified two additional rhyolitic eruptions in the region from two other eruptive sources: one during the Early–Holocene and another in the Late–Holocene. The identification and characterisation of these significant volcanic events provide new constraints into regional Ho","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"32 1","pages":"88"},"PeriodicalIF":0.7,"publicationDate":"2019-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75164846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}