ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2018-05-07
    Description: Dada la importancia que revisten los suelos en los procesos que ocurren en la zona crítica (zona de interacción entre agua, suelo, aire, organismos), en este trabajo presentamos la distribución temporal y espacial de una secuencia de paleosuelos arcillosos con carbonatos secundarios (capas de caliches y carbonatos diseminados) en el sector nororiental de la Cuenca de México, particularmente en el valle de Teotihuacán. El propósito de este trabajo consiste en reconstruir la distribución temporal y espacial de la cubierta de suelos del pasado para entender su relación con la estructura actual de suelos y sedimentos en este sector semiárido de la cuenca de México. Con esta información, determinar la participación de estos materiales en la Zona Crítica (ZC). Para ello, se ha llevado a cabo un transecto de dirección norte-sur, que inicia en las elevaciones del Cerro Gordo, cruza el valle de Teotihuacán y termina en la Sierra Patlachique, describiendo perfiles de suelo en diferentes posiciones geomorfológicas. El marco cronológico se ha establecido con base en fechamientos de radiocarbono realizados en las capas de caliches. De acuerdo a la cronología, al tipo y grado de pedogénesis, y a los procesos de sedimentación, se han reconocido cuatro unidades. La primera unidad, denominada Paleosuelos del Pleistoceno, fase I (50000 – 20000 años AP), está compuesta de paleosuelos arcillosos, los cuales son Luvisoles crómicos y estágnicos, dependiendo de su posición en el paisaje. Estos paleosuelos muestran tanto carbonatos secundarios diseminados y en fracturas, como capas de caliches. En la segunda unidad, Paleosuelos del Pleistoceno, fase II (20000 –10000 años AP), dominan los sedimentos sobre los suelos; únicamente en el fondo del Valle, se han encontrado Gleysoles cortados por canales aluviales. La unidad, Paleosuelos del Holoceno, fase I (10000 a 1000 años AP) se caracteriza por presentar suelos poligenéticos (Vertisoles), fuertemente modificados por los procesos antrópicos, durante las diversas fases de ocupación pre-hispánica. La última unidad, Suelos del Holoceno, fase II, abarca el último milenio, en donde se destacan procesos de erosión e inestabilidad del paisaje. La tendencia principal en la distribución espacial de los paleosuelos es la siguiente: las unidades antiguas (Luvisoles, capas de caliches y Vertisoles) están sepultadas profundamente en el fondo del valle. Sin embargo, en los taludes y elevaciones montañosas, pueden aparecer cerca o directamente sobre la superficie, siendo incorporados en el manto de suelos actual. Las interrelaciones entre los diferentes paleosuelos a lo largo del transecto estudiado, junto con las observaciones micromorfológicas, apoyan la hipótesis de una relación evolutiva entre los Luvisoles pleistocénicos y los Vertisoles del Holoceno. Consideramos que estas diferentes unidades repercuten en los procesos hidrológicos en el valle y que las capas de caliche formadas en los ambientes pleistocénicos pueden afectar la geoquímica del agua subterránea así como sus firmas isotópicas.
    Description: As soils are important elements for the processes involved in the critical zone (the zone of interaction between water, soil, air, and organisms), in this work we present the temporal and spatial distribution of a clayey-paleosol sequence with secondary carbonates (layers of caliche and disseminated carbonates) in the northeast sector of the Mexico Basin, particularly in the Teotihuacan Valley. The goal of this paper is the temporal and spatial reconstruction of the past soil cover to understand its relationship with the present day soils and sediments in this semiarid sector of the Mexico Basin. With this information the involvement of these materials in the critical zone could be determined. To comply with these objectives, a north-south transect was carried out, starting in the Cerro Gordo, crossing the Teotihuacan valley and ending in the Sierra Patlachique, describing soil profiles located in different geomorphological positions. The chronological framework has been established with radiocarbon dates of the caliche layers. According to this chronology, the type and degree of pedogenesis, as well as the sedimentation processes, four units have been recognized. The first unit is named the Pleistocene Paleosols, phase I (50000 – 20000 years BP), and is composed of clayey paleosols, chromic and stagnic Luvisols, depending on their position in the landscape. These paleosols contain pedogenic carbonates, disseminated and in fractures, and caliche layers. In the second unit, the Pleistocene Paleosols, phase II (20000 –10000 years BP), sediments predominate over soils; only in the valley floor some Gleysols are found to be cut by alluvial channels. The unit, Paleosols of the Holocene Paleosols unit, phase I (10000 to 1000 years BP), is characterized by polygenetic soils (Vertisols) strongly modified by anthropic processes during distinct phases of pre-hispanic occupation. The last unit, the Holocene Soils, phase II, covers the last millennium when erosional processes and unstable landscape dominate. The paleosols (Luvisols, caliche layers, and Vertisols) are deeply buried at the bottom of the valley. However, on the slopes and hilltop positions, they can appear close to or directly on the surface, being incorporated in the present day soil mantle. Spatial interrelations of different paleosols along the studied transect together with micromorphological observations support the hypothesis of an evolutionary link between the Pleistocene Luvisols and the Holocene Vertisols. We propose that these different units are involved in the hydrological processes in the valley and that the caliche layers, formed in the Pleistocene environments, can affect the geochemistry of the groundwater as well as its isotopic signatures.
    Keywords: paleosuelos; Teotihuacán; caliches; Luvisoles; Vertisoles; cuenca de México; paleosols; Teotihuacan; caliches; Luvisols; Vertisols; Basin of Mexico
    Language: Spanish
    Type: article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2017-06-10
    Description: The route of the field trip described in this excursion guide follows a section through Germany from North to South, from the area of the Northern glaciation, to the Alpine glacial advances. It includes several places of historical importance, where milestones in Quaternary research have been achieved in the past, as well as new interesting sites where results of recent research is presented.
    Description: excursionGuide
    Keywords: V 000 ; VCA 520 ; Geologische Wissenschaften ; Quartärgeologie ; coastal evolution; Rügen ; Geopark Mecklenburg Ice Age Landscape ; tourism ; quaternary ; Halle ; Main ; sedimentology ; landslide ; natural hazards ; danube ; rhine ; pleistocene ; holocene ; geology
    Language: English
    Type: anthology , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2015-06-01
    Description: PurposeThis paper reports on extremely thick and massive duricrusts in soils of two basins in the Alentejo (southern Portugal). Since different types of duricrusts (calcretes, silcretes and palycretes) have been reported from other regions in the Mediterranean, the purpose of this study was to identify the cementing agents in the duricrusts and to compare their composition in the two basins. Moreover, the study aimed at identifying the processes involved in duricrust formation, and especially the role of topography and lateral water and element transport in the landscape, and drawing conclusions about environmental conditions and time of duricrust formation.Materials and methodsAfter studying an extensive number of road cuts in the field and mapping soil patterns in parts of the two basins by manual augering, ten pedons were selected for detailed description and sampling. Thin sections were analysed under a petrographic microscope, focusing on the micromorphology and optical properties of the cementing materials. Selected samples were studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy to reconfirm the optical identification. The laboratory analyses included pH, carbonate contents, and X-ray diffraction analysis.Results and discussionThe duricrusts in the eastern Sado basin are indurated by silica. Combination of XRD and thin section analysis allowed to identify opal-CT as a major component, while opal-A is present to a lesser extent, and chalcedony is very rare. The cementing materials of the duricrusts in the Oriola basin are palygorskite and calcite, which may occur alone or in combination within a soil profile.ConclusionsThe thick duricrusts formed in the basins through precipitation of calcite, palygorskite and silica from lateral water flows, which ran from the Serra de Portel into the basins, during short moist seasons in a generally warm, semi-arid climate with strong evapotranspiration. Lithology of the upper catchment areas (element sources) and topography control the spatial distribution of the different duricrusts. Their formation took place mainly during the Pliocene. Palygorskite transformation to smectite in the upper parts of the palycretes indicates that palygorskite is unstable in the present (more humid, typical Mediterranean) climate. This study demonstrates the potential role of lateral water and element transport in landscapes that need to be considered in pedological studies and concepts, and the use of mineral indicators of past climates such as palygorskite and the ageing stage of silica precipitations as tools for reconstructing environmental conditions and possible time of duricrust formation. ©2015 Springer-Verlag Berlin Heidelberg
    Print ISSN: 1439-0108
    Electronic ISSN: 1614-7480
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2018-10-31
    Print ISSN: 0033-5894
    Electronic ISSN: 1096-0287
    Topics: Geography , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉〈p〉The appearances of palaeosurfaces intercalated into palaeo-dune fields on Fuerteventura are multifaceted. Although reddened layers in these dune sediments might suggest that strong soil-formation processes have taken place, the combination of aridity and parent material, namely biogenic carbonate sand of shelf origin, reveals that strong soil formation seems unlikely. These sediments rather represent de- and recalcification processes only. Solely in the case of admixed material of volcanic origin and dust deposits further soil-forming processes seem to be possible. Hematite-rich Saharan dust contributes to reddish colouration of the palaeosurfaces. In addition, CaCO〈span〉3〈/span〉-coated iron particles appear to be ingredients of dust being leached after deposition and transformed to hematite. Overall, we propose much weaker soil-forming processes during the Pleistocene than previously postulated. Our findings support the relevance of local environments. Carbonate sands of shelf origin hinder strong soil formation and the reddish layers separating dune generations are palaeosurfaces, which mainly consist of Saharan dust. After deposition of allochthonous material, these layers are overprinted by weak soil-forming processes. The formation of palaeosurfaces primarily depends on morphodynamically stable periods during limited sand supply. Our data suggest a cyclicity of processes in the following order: (1) sand accumulation, (2) dust accumulation and weak soil formation, and (3) water-induced erosion. For the Canary Islands, we support the assumption of glacial maxima being periods of increased levels of moisture. In combination with rising sea level, we propose that favorable conditions of surface stability occur immediately after glacial maxima during periods of starting transgression, whereas regression periods immediately after sea-level high stands seem to yield the highest sand supply for the study area.〈/p〉〈/div〉
    Print ISSN: 0033-5894
    Electronic ISSN: 1096-0287
    Topics: Geography , Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...