Estudios Geologicos-Madrid最新文献

{"title":"Registro fósil y distribución de Anadenathera en Argentina desde el Mioceno hasta la actualidad","authors":"L. Fernandez-Pacella","doi":"10.3989/EGEOL.41834.343","DOIUrl":"https://doi.org/10.3989/EGEOL.41834.343","url":null,"abstract":"Currently Fabaceae, is one of the dominant families of the Seasonally Dry Tropical Forests or Neotropical seasonal dry forests. Anadenanthera which integrates the family, has wide geographical distribution in South America and the West Indies, but in Argentina it`s only present Anadenantera colubrina var. cebil in the north and their records are represented from the Miocene to the present through palynomorphs and mineralized woods. The main objective of this work is to contribute to the understanding in the context of the history of Anadenanthera during the Neogene and Quaternary in Argentina, on the basis of the review and integration of the paleobotanical history, geological and climatic available that have affected the genre in the country. Studied fossil materials come from different geological formations of Argentina: Chenque Formation (Miocene), Parana Formation (Middle Miocene), San Jose Formation (Middle Miocene), Ituzaingo Formation (Pliocene) and Ibera (Holocene). The material found on the Chenque Formation is referred to Polyadopollenites coincides with the described material for the Middle Miocene of the central-eastern Argentina and the Pliocene of northeast Argentina. On the other hand in Parana and Ituzaingo Formation studied sample of mineralized woods of Anadenantheroxylon villaurquisense , finally the sample found in Holocene of Ibera Corrientes Province corresponds to Anadenanthera colubrina var. macrocarpa . With these data it can be concluded that Anadenathera had a wide geographical record in Miocene and Holocene of Argentina, it was found in sediments from the lower Miocene of Patagonia by integrating a Subtropical Paleoflora. From the Middle-Upper Miocene integrated the vegetation in northeast Argentine constituting xerophiles forests. Their last record is equivalent to the Middle Holocene of sediments from Ibera integrating the regional vegetation and indicating an open vegetation characteristics of dry environments. Finally it`s noteworthy that the spatial and temporal succession of Anadenanthera in Argentina, would have been intimately associated with tectonic and climatic events occurred during the Neogene and Quaternary.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2015-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82225737","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":"Experimentos de disolución de CaCO 3 en foraminíferos bentónicos aglutinados del Paleoceno-Eoceno en Zumaya (Cuenca Vasco-Cantábrica, España)","authors":"G. Arreguín-Rodríguez, L. Alegret","doi":"10.3989/EGEOL.41758.330","DOIUrl":"https://doi.org/10.3989/EGEOL.41758.330","url":null,"abstract":"The largest extinction of deep-sea benthic foraminifera in the Cenozoic occurred during the Paleocene-Eocene Thermal Maximum event (PETM, ~55.8 Ma). Much has been speculated about the causes of such extinction, and proposed mechanisms include changes in productivity and/or oxygenation of bottom waters, metabolic changes and in the composition of the food supply to the seafloor, or the ocean acidification related to the massive input of isotopically light carbon into the ocean-atmosphere system, among others. \u0000Here we analyse ocean acidification as a potential triggering mechanism of the extinctions. The early Eocene at the Zumaya section (Basque-Cantabrian Basin) is marked by a 4 m-thick interval with a very low CaCO 3 content. In order to analyse whether CaCO 3 dissolution had a direct effect on the extinctions across the PETM, we car-ried out dissolution experiments on various species of agglutinated benthic foraminifera from Zumaya. In general, agglutinated species that do not disappear in the interval of most intense dissolution at Zumaya were not -or only slightly- affected by our dissolution experiments, since they do not have calcareous particles or cement. However, some species that went extinct or locally disappeared during the early Eocene, such as Dorothia cylindracea, Spiroplectammina spectabilis and Haplophragmoides cf. walteri , are resistant to dissolution. These results sug-gest that, in addition to ocean acidification, other factors must have contributed to the destabilization of benthic foraminiferal assemblages.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2015-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77658318","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":"Biocronología de la Terraza Compleja de Butarque del río Manzanares en el Estanque de Tormentas al sur de Madrid (España)","authors":"C. Laplana, E. Herráez, J. Y. S. D. L. Terreros, S. Bárez, Susana Rubio-Jara, Joaquín Panera, I. Rus, A. Pérez-González","doi":"10.3989/EGEOL.41808.338","DOIUrl":"https://doi.org/10.3989/EGEOL.41808.338","url":null,"abstract":"Due to the construction of the Stormwater Tank in Villaverde (Madrid), two new Pleistocene vertebrate bearing sites were discovered within the sediments of the Complex Terrace of Butarque (TCB, in Spanish), called H-02 and H-03. Termoluminiscence (TL) dates placed the first site at the Late Pleistocene, more precisely at the end of the MIS 5. An older age within the Middle Pleistocene was obtained for H-03 (Dominguez-Alonso et al. , 2009). In this work, we evaluate the agreement between the TL dates and the estimated ages resulting from the biochronological interpretation of the fossil mammal assemblages recovered in both sites. Whereas for H-03 there is consistency between the TL dating and the age estimated based on biocronological criteria, this is not the case for H-02. At this site, the presence of Microtus brecciensis points to an older age than the proposal based on TL, within the Middle Pleistocene. On the other hand, comparison of some biometric features between the H-02 and Aridos 1 populations of the last species allows to establish a younger age for the first site with regard to the second one. Taking into account the available dates for Aridos 1, which placed this site at the end of the MIS 11 (Panera et al. , 2011), the age of H-02 must therefore be included in the last quarter of the Middle Pleistocene. In summary, TL dates for the H-02 site and, perhaps, some others obtained for the Stormwater Tank in Villaverde, seem to be minimum estimations of the age of the sediments, and do not represent their real age.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2015-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75329312","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":"Caracterización mineralógica y geoquímica de minerales hidratados de ambientes subterráneos: implicaciones para la exploración planetaria","authors":"Fernando Gázquez, F. Rull, José María Calaforra, G. Venegas, José Antonio Carbonero Manrique, A. Sanz, Jesús Medina, A. Catalá-Espí, A. Sansano, R. Navarro, Paolo Forti, J. D. Waele, J. Martínez-Frías","doi":"10.3989/EGEOL.41688.314","DOIUrl":"https://doi.org/10.3989/EGEOL.41688.314","url":null,"abstract":"The recent discovery of hydrated sulfates on the Martian surface suggests that widespread wet conditions were present during its early geological history. Upon this discovery, a growing interest has emerged in the study of this group of minerals from terrestrial environments as potential Martian analogs. Here, we evaluate the potential of various analytical techniques involved in current and future mission to Mars for detecting hydrated minerals from caves and mines of Spain and the mining district of Iglesias-Carbonia (Sardinia, Italy). Minerals were analyzed by Raman spectroscopy, which will be included in the payload of the ESA’s 2018 ExoMars mission. On the other hand, IR spectroscopy, also included in the ExoMars mission, as well as LIBS spectroscopy and a combined XRD-XRF analyzer, both onboard the Curiosity rover of NASA’s MSL mission, were utilized. Hydrated sulfates (gypsum, epsomite, jarosite and glaucocerinite), silicates (hemimorphite) and carbonates (hydrozincite and hydromagnesite) were characterized. Most of these minerals have also been detected on the Martian surface. The mechanisms involved in the genesis of these minerals and the potential analogies with the minerogenesis on Mars are discussed. The Raman-LIBS combination appears to be the most powerful tool for detecting hydrated minerals in Martian conditions. This technology will probably be considered to be onboard of further planetary missions.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81606833","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":"Análisis espectral de materiales geológicos en la Cordillera Volcánica Central de Costa Rica y su relación con la detección remota de anomalías","authors":"J. G. Rejas, J. Martínez-Frías, R. Martínez, Miguel Marchamalo, J. Bonatti","doi":"10.3989/EGEOL.41711.313","DOIUrl":"https://doi.org/10.3989/EGEOL.41711.313","url":null,"abstract":"The aim of this work is the comparative study of methods for calculating spectral anomalies from imaging spectrometry in several test areas of the Central Volcanic Range (CVR) of Costa Rica. In the detection of anomalous responses it is assumed no prior knowledge of the targets, so that the pixels are automatically separated according to their spectral information significantly differentiated with respect to a background to be estimated, either globally for the full scene, either locally by image segmentation techniques. \u0000We used spectral ranges of visible-near infrared (VNIR), shortwave infrared (SWIR) and thermal (TIR) data cubes hiperepectrales from HyMAP airborne sensors and MASTER. We have designed experiments on natural scenes of the CVC, and semi-urban of different complexity, analyzing the behavior of the standard RX (Reed & Xiaoli, 1990) anomaly detector and different approaches based on imaging and dimensionality reduction. In this paper we propose a new technique for anomaly detection in hyperspectral data called DAFT (Detector de Anomalias de Fondo Termico), as a Projection Pursuit (Malpica et al. , 2008) variant, based on dimensionality reduction by projecting anomalies or targets with unknown spectral signature to the background, in a range thermal spectrum wavelengths. We discuss the results considering their implications on geological processes, as well as their use as terrestrial analogs for planetary exploration.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81797978","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":"De los dioses a los hombres: Un recorrido histórico del descubrimiento de los elementos químicos","authors":"I. González","doi":"10.3989/EGEOL.41718.316","DOIUrl":"https://doi.org/10.3989/EGEOL.41718.316","url":null,"abstract":"To achieve the apparently simple Periodic Table of the Elements has implied tremendous efforts over thousands of years. In this paper we present a brief history of the discovery of the chemical elements from prehistory to the present day, revealing the controversies that arose on the way and claiming the important work performed by alchemists in the advancement of knowledge. This is especially important if we consider that alchemy had a period of existence of many thousands of years, while the “Chemistry”, officially established as a science in the eighteenth century, has operated as such for only a few hundred years. Even so, if we consider the progress of discovery and isolation of chemical elements throughout history, it can be observed that the number of elements identified is achieved mainly in the nineteenth and twentieth centuries, reflecting the development of instrumental techniques, that facilitated this task.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88173448","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 granito de Pedregal (Portugal): caracterización petrográfica y geoquímica de un granitoide peculiar","authors":"J. A. Ferreira, M. A. Ribeiro, H. Martins","doi":"10.3989/EGEOL.41730.321","DOIUrl":"https://doi.org/10.3989/EGEOL.41730.321","url":null,"abstract":"The Pedregal granite outcrops in the Central Iberian Zone, northern Portugal, in the eastern border of a synorogenic variscan granite-migmatite complex sub-concordant with the regional metamorphic structures. It is a granitoid (ca. 3 km 2 ) with an elongated NW-SE shape intruded in staurolite-micaschist and banded gneiss-migmatite rocks, with local igneous breccias in the contact. The country rocks belong to a metapelitic and metasammitic sequence of Edicarian-Cambrian age, known as the “Complexo Xisto-Grauvaquico” (CXG) which shows a main regional foliation with a NW-SE to NNW-SSE direction. The Pedregal granite is peraluminous (its A/CNK parameter ranges from 1.18 to 1.62), with a magnesian and alkali to alkali-calcic signature. The peculiar features of the granite are high contents of Zr (389 to 435 ppm) and a LREE flat pattern, which are uncommon characteristics for granitic rocks, as well as the corroded shape of the biotite, and the large amount of secondary muscovite. These peculiar features distinguish it from the adjacent synorogenic granites. \u0000The field, petrographical and chemical features of the Pedregal granite are in accordance with a second phase of partial melting of a residuum, depleted by melt segregation during a first melting episode with the involvement of peritectic garnet and abundant residual biotite with LREE- and Zr-bearing accessory minerals. Besides, the intrusive character of the granite, and the presence of metasedimentary xenoliths point out to a secondary diatexite.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87651001","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":"Composición del circón de granitos variscos del Norte de Portugal","authors":"H. Martins, J. Abreu","doi":"10.3989/EGEOL.41729.318","DOIUrl":"https://doi.org/10.3989/EGEOL.41729.318","url":null,"abstract":"A group of slightly peraluminous Variscan plutons in Northern Portugal were selected from the study of zircon composition. The selected plutons are: the Vila Pouca de Aguiar and the Lavadores-Madalena plutons with I-type affinities and the Vieira do Minho pluton, an l-S transitional type. Zircon occurs as euhedral to subhedral crystals and exhibit finely concentric oscillatory magmatic zoning mainly related to variations of Hf, Y, U and Th concentrations. Most zircon crystals show the dominant “xenotime” substitution. The zircon crystals have Zr/Hf ratio in the range of 21 to 52, with no significant differences between the different granites. These values are in the same range of other peraluminous granites and are in accordance with a crustal signature of zircon. Moreover, the range of Zr/Hf values in zircon crystals overlaps with that of crustal sources and consequently to the potential protoliths proposed in the genesis of the Vieira do Minho and the Vila Pouca de Aguiar plutons, namely meta-igneous crustal sources at different levels. Although zircon from the Lavadores-Madalena pluton has a compositional range similar to the other plutons, an origin by hibridisation has been proposed. However, similar zircon chemistry between this pluton and Vila Pouca de Aguiar and Vieira do Minho plutons could also suggest a similar crustal source.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90081809","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 los modelos hidrogeoquímicos de génesis de tobas calcáreas","authors":"S. Ordóñez, D. Benavente","doi":"10.3989/EGEOL.41753.325","DOIUrl":"https://doi.org/10.3989/EGEOL.41753.325","url":null,"abstract":"The calcareous tufa deposits in fresh waters are widely represented in the Iberian Peninsula, mostly related to springs from carbonate aquifers. Most studies on the geochemical modelling of the genesis of calcareous tufa consider the meteoric water percolating through the limestone aquifer is enriched in CO₂ by existing microbiological activity in soil. The new equilibrium with atmospheric CO₂ in springs and/or metabolic activity of microorganisms determines a rich variety of facies of calcareous tufa. The resulting water has a calcium bicarbonate nature. However, the hydrochemical modelling has not completely been addressed and the boundary conditions have not been taken into account in tufa systems in which soils present low CO₂ concentrations or when the nature of waters are Ca-Mg-SO₄-HCO₃. \u0000In this paper, hydrochemical results from two important examples of genesis of calcareous tufa are presented: Jucar river (Valdeganga - Presa de la Central Hidroelectrica del Bosque) and Guadiana Alto river (Ruidera pools). These results are also compared with other kart spring waters recently studied in the area. The water nature of Jucar river and Ruidera aquifers shows clearly a Ca-Mg-SO₄-HCO₃ facies. The hydrochemical interpretation cannot exclusively be explained using the CO₂–H₂O– calcite system, which has widely been used in studies of precipitation rates and paleoclimatic records of calcareous tufa or Karstification reactions of limestone aquifers. In this review, we evaluate the dedolomitization and gypsum dissolution, which are independent of partial pressure of CO₂, and kinetics and sustainability of processes in terms of genesis of tufa systems. We also consider other CO₂-dependent reactions such as the calcification gypsum and dissolution and precipitation of calcite by mixing waters. This explains the nature of waters from dolomite-gypsum aquifers and also their great generator potential of tufa systems, and refuses the interpretation based exclusively on the presence of humic acid-rich soils, not very common in arid and semi-arid areas. Finally, we examine mixing waters in multi-layered or compartmentalized seasonally aquifers, which can produce waters that develop calcareous tufa.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88212453","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":"Composición isotópica (δ¹⁸ O y δD) de espeleotemas silíceos en las cuevas volcánicas de Algar do Carvão y Branca Opala (Isla Terceira, Azores, Portugal)","authors":"D. Daza, M. Bustillo, C. Recio, M. R. Carvalho, J. Nunes","doi":"10.3989/EGEOL.41717.315","DOIUrl":"https://doi.org/10.3989/EGEOL.41717.315","url":null,"abstract":"The volcanic caves of Algar do Carvao (a pit with a complex genesis) and of Branca Opala (a lava-tube cave), differ from other caves on the island of Terceira by having speleothems composed only by opal. This kind of speleothems, in volcanic caves, suggests that the silica origin can be related to hydrothermal activity. The objective of this study is to determine the speleothem isotopic composition in δ¹⁸O SMOW and δD SMOW to determine their geochemical signature and conditions of formation. \u0000The studied samples from Algar do Carvao pit are stalactites and flowstones/gours that have been formed in subaerial conditions, while those from the Branca Opala lava tube have been defined as underwater silica stromatolites. \u0000dD data of speleothems from both caves are relatively similar (−102.0 ± 10.5‰ in Branca Opala and −103.7 ± 11.1‰ in Algar do Carvao) and it can be assumed that the fluids involved in the silica deposition may be similar. Moreover the δ¹⁸O SMOW data show that the Algar do Carvao speleothems have higher values (δ¹⁸O SMOW 39,4 ± 0,3‰), relatively to the Branca Opala stromatolites (δ¹⁸O SMOW 35,2 ± 0,8‰). The diagenesis that affected the opal A may explain, in part, the observed differences. However, other genetic factors are also influencing such as the fact that Algar do Carvao stalactites are formed in sub aerial conditions, under the influence of evaporation processes, while Branca Opala speleothems were formed in underwater conditions. However, it is also possible, that the water that originated the Branca Opala speleothems was 10,7 °C warmer than the water that formed the Algar do Carvao stalactites.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76932728","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}