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Bijeesh KOZHIKKODAN VEETTIL Ulisses FRANZ BREMER Atilio EFRAIN BICA GRONDONA Sergio FLORENCIO DE SOUZA 《山地科学学报》2014,11(2):398-406
Recent changes occurred in terminus of the debris-covered Bilafond Glacier in the Karakoram Range in the Himalayas, Northern Pakistan was investigated in this research. Landsat MSS, TM and ETM＋ images were used for this study. Digital elevation models derived from ASTER GDEM and SRTM were also utilized. Visible, infrared and thermal infrared channels were utilized in order to get accurate glacier change maps. Three methods were tried to map this debris-covered glacier in this research. The glacier has been mapped successfully and the changes in the glacier terminus from 1978 to 2011 have been calculated. Manual, semi-automatic and thermal methods were found to give similar results. It was found that the glacier has undergone serious ablation during this period despite of the fact that many of the larger glaciers in the Hindu Kush and Karakoram mountain regions in the Upper Indus Basin were reported to be expanding. The terminus has been moved back about 600 meters during this period and there was an abrupt change in the glacier terminus during 1990-2002. We propose that debris thickness is not the only factor that influences the glacier ablation but the altitude of the debris-covered glacier as well. Many glaciers in the Karakoram region reported to be expanding were having higher altitudes compared to the study area. 相似文献
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Bijeesh Kozhikkodan Veettil Éder Leandro Bayer Maier Ulisses Franz Bremer Sergio Florencio de Souza 《Climate Dynamics》2014,43(12):3439-3448
This paper describes the application of remote sensing in monitoring the fluctuations in one of the mountain glaciers in the Ecuadorean Andes during the past few decades using ASTER, EO-1 ALI, Landsat MSS, TM and ETM + images. Satellite images were used to calculate the snow line altitudes (SLAs) during the period 1979–2013. Cotopaxi ice covered volcano was studied as representative of Ecuadorian glaciers in the eastern cordillera. Precipitation and air temperature data from various gauging stations within the range of 30 km from the study site and monthly discharge and water level data from a gauging station were also utilized in this study. Anomalies in precipitation and temperature were found to be slightly different in the Cotopaxi region compared to nearby Antizana in the same cordillera and Chimborazo region in the western cordillera. An attempt to correlate the El Niño—southern oscillation phenomenon with the glacier fluctuations in Ecuadorian Andes was done successfully. Cold and warm regimes of Pacific Decadal Oscillation is also considered. The calculated glacier fluctuations obtained were similar to that performed on the nearby Antizana 15 in the eastern cordillera during 1995–2002. Precipitation and temperature anomalies were similar with Antizana 15. It is evident from the research that SLAs were highly fluctuated between the period of occurrence of El Niño and La Niña events. It is also seen that the glacier fluctuations show a negative mass balance trend in during the warm regime of Pacific Decadal Oscillation during the past three decades. Glaciated areas were advanced during the La Nina events in the cold regime of PDO during 1998–2002. 相似文献
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Color removal was evaluated in anaerobic assays using synthetic (SE) and real (RE) effluents containing the dye Direct Black 22 (DB22). The focus was on the individual influence of two electron donors (EDs), sucrose and ethanol; and their combination with two redox mediators (RMs), lawsone and riboflavin. In addition to SE assays, the EDs were combined with sulfate which was present in the RE. Distinct behavior was observed with both assays. In the case of SE, using the EDs sucrose and ethanol resulted in DB22 removal efficiency of 93 and 83%, respectively; but only 27% in the control. The respective removal rates were 27.8‐ and 4.4‐fold higher than that of the control. Using the EDs with the RM lawsone resulted in color removal higher than that with riboflavin. Interestingly, in the ethanol + sulfate assay, late release of the last was observed, possibly due to the desulfonation reaction of the aromatic structures during the DB22 molecule breakdown. In the case of RE, no improvement was observed with either EDs; and some combinations with the RMs even resulted in decreased color removal. Therefore, the used EDs and RMs showed positive effect on color removal in SEs; but unexpectedly not in REs. 相似文献
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Hubert Miller Christopher Adams Florencio G. Aceñolaza Alejandro J. Toselli 《International Journal of Earth Sciences》2011,100(2-3):619-629
The evolution of the provenance areas for Late Neoproterozoic, Cambrian and Early Ordovician sedimentary and meta-sedimentary rocks of north central and northwest Argentina is discussed using 123 maximum ages of detrital zircons from 42 samples from this and previously published studies. Most detrital zircon ages fall into two groups: 1,200–900 Ma and 670–545 Ma. These ages are essentially identical for the non- to very low grade metamorphic late Neoproterozoic to Early Cambrian Puncoviscana Formation and the low to high grade metamorphic rocks of Eastern Sierras Pampeanas. Hence, both units are related to similar provenance areas at the same time of sedimentation. The time span from zircon crystallization in the Earth’s crust to exhumation and erosion may be very long. This is important when determining maximum ages of sedimentary rocks. Variation of zircon maxima may also be influenced by concurrent sedimentary cover of proposed provenance areas. For the late Mesoproterozoic to early Neoproterozoic zircon age group, an active mountain range of the southwest Brazilian Sunsás orogen is the most probable provenance area. The younger, late Neoproterozoic zircons are related to the continuously developing mountains of the Brasiliano orogen of southwest and south central Brazil. Young zircons, up to 514 Ma, from fossil-bearing Puncoviscana and Suncho Formation outcrops are related to late Early Cambrian volcanism contemporaneous with sedimentation. This situation continues through the Late Cambrian to the Early Ordovician, but the Sunsás orogen provenance diminishes as possible Río de la Plata craton origins become important. 相似文献
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Abstract: We present results tending to characterize the new records of invertebrates from the Yacoraite Formation (Maastrichtian-Danian). The fossils reported come from two stratigraphic sections exposed in the surroundings of Maimará and Jueya, province of Jujuy, northwestern Argentina. The selection was based on geological and paleontological evidence. The recovered fossils include gastropods and invertebrate fossil traces, including Planolites, Skolithos and Gastrochanoelites ichnogenus. As result of our review, we discussed the possibility of assigning the analyzed gastropods to the family Zygopleuridae (gene. et. sp. indet.), as an approximation to the taxonomic resolution of this fossil fauna. The trace fossils were assigned to the archetypical Glossifungites ichnofacies. The study of the fossil assemblage allowed us to define a shallow depositional environment, characteristic of a marine context with high-energy conditions. 相似文献
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Mikel A. Marquiegui Florencio Aguirrezabalaga 《Estuarine, Coastal and Shelf Science》2009,84(4):598-604
The colonization process by macrobenthic infauna after the completion of managed realignment on the fertile plain of Jaitzubia, along the Bidasoa estuary, is assessed here. The benthic invertebrate fauna was sampled annually for three years in the newly recovered intertidal areas. The results show a rapid colonization process. Six months after the completion of the restoration works, all the stations exhibited a large number of small opportunistic benthic species, as well as some large individuals of Hediste diversicolor, that dominated the biomass of the community. One year later, a new stage of development or succession towards the settlement of the Scrobicularia plana–Cerastoderma edule community was observed, showing a reduction of both abundance and species richness, and an increase in biomass, mainly due to the presence of individuals of S. plana (which were absent previously). The following year, a further reduction in the abundance and number of species was observed, as well as an increase in biomass, but on this occasion S. plana was the main contributor to community biomass. Evidence of the importance of passive or active dispersion in the adult stage of the species H. diversicolor and S. plana in the recovery process was also observed. 相似文献
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The hypothesis of exotic terranes in Perú, Bolivia, Argentina and Chile generated discussions on the mode of transfer and extent of accretional events that may have occurred in the southern Andes during the Late Proterozoic–Early Paleozoic. Initially, a tectogenesis based on autochthonous mobile fold belts was discussed. Following ideas emphasised the fragmentation of the supercontinent Rodinia, Laurentia moving along the West Gondwana border and colliding with the Gondwana western margin. The most important effect of this Laurentia/Gondwana relationship was attributed to the Argentine Precordillera (or Cuyania) terrane splitting off from Laurentia and docking to Gondwana in the Early Paleozoic. In this study, the most cited arguments for this Laurentia/Precordillera relationship are discussed, emphasising paleontological considerations. It is shown that these arguments do not exclude a close original vicinity of the Precordillera terrane to Gondwana.The Precordillera terrane is suggested to be part of a hypothetical platform, which developed between South America, Africa and Antarctica (SAFRAN platform), and which was displaced to its actual position by transcurrent faults. The collisional events in the Sierras Pampeanas ensued from strike–slip movements and were responsible for the S and I type transpressional magmatism along the Pampean and Famatinian terranes. The final result of this continent-parallel movement of terrane slices is similar to that of a terrane split off from Laurentia, but the first-named way of formation easier explains the general continuity of plate convergence at the western border of Gondwana than the Laurentia/Precordillera connection does. 相似文献
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Pavel JeŽek Dipl.-Geol. Dr. Arne P. Willner Prof. Dr. Florencio G. AceÑolaza Prof. Dr. Hubert Miller 《International Journal of Earth Sciences》1985,74(3):573-584
During the Late Precambrian to Early Cambrian a large basin with a homogeneous psammitic-pelitic sediment fill existed in the area of the NW-Argentine Andes. It is now exposed in different tectonic levels. This basin of meridional elongation was situated on a stable continental margin at the western edge of the Brazilian shield. It was underlain by segmented older continental crust. According to the modal and chemical composition of the greywackes and subgreywackes a predominant metasedimentary source may be supposed. Four clastic facies types indicate a transport by gravity currents within a submarine fan system, while massive red pelites represent cut-off periods, and rare carbonates deposition on rises. The gravity currents derived from easterly directions. The sedimentation age is proved by a rich ichnofauna and some medusoid impressions.
Zusammenfassung Im Jungpräkambrium bis Unterkambrium existierte im Bereich der NW-argentinischen Anden ein ausgedehnter Trog mit homogener psammitisch-pelitischer Füllung, die heute in verschiedenen Gebirgsstockwerken aufgeschlossen ist. Dieses Becken lag an einem stabilen Kontinentalrand im Westen des Brasilianischen Schildes und war von segmentierter älterer, kontinentaler Kruste unterlagert. Nach der modalen und chemischen Zusammensetzung der Grauwacken und Subgrauwacken sind überwiegend metasedimentäre Herkunftsgesteine anzunehmen. Vier klastische Faziestypen lassen auf Transport durch Trübeströme in submarine Fächer schließen, während mächtige Rotpelite Ruhezeiten und die seltenen Karbonate Ablagerungen auf Schwellen anzeigen. Die Schüttungen stammen aus östlichen Richtungen. Das Sedimentationsalter ist durch eine reichhaltige Ichnofauna und einige Medusenabdrücke dokumentiert.
Résumén Durante el Precámbrico superior hasta el Cámbrico inferior en los Andes del NW Argentino se extendía una larga cuenca rellena de sedimentos psamo-pelíticos homogéneos, que hoy afloran en distintos pisos tectónicos. Esta cuenca de elongación meridional estaba situada en un margen continental estable al lado occidental del escudo brasileño, sobre corteza continental segmentada más antigua. Según su composición modal y química, las grauvacas y subgrauvacas derivaron predominantemente de rocas metasedimentarias. Cuatro tipos de facies clásticas indican su transporte en corrientes de gravedad, provenientes del este, y sedimentación en conos submarinos. Pelitas rojas macizas representan períodos de sedimentación pelágica, mientras que los escasos carbonatos se depositaron en dorsales. Una icnofauna amplia y algunas impresiones de medusoides documentan la edad de sedimentación.
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