Propagation of orographic barriers along an active range front: insights from sandstone petrography and detrital apatite fission-track thermochronology in the intramontane Angastaco basin, NW Argentina     

Isabelle Coutand †  Barbara Carrapa†  Anke Deeken‡  Axel K. Schmitt§  Edward R. Sobel†  Manfred R. Strecker† 《Basin Research》2006,18(1):1-26

The arid Puna plateau of the southern Central Andes is characterized by Cenozoic distributed shortening forming intramontane basins that are disconnected from the humid foreland because of the defeat of orogen‐traversing channels. Thick Tertiary and Quaternary sedimentary fills in Puna basins have reduced topographic contrasts between the compressional basins and ranges, leading to a typical low‐relief plateau morphology. Structurally identical basins that are still externally drained straddle the eastern border of the Puna and document the eastward propagation of orographic barriers and ensuing aridification. One of them, the Angastaco basin, is transitional between the highly compartmentalized Puna highlands and the undeformed Andean foreland. Sandstone petrography, structural and stratigraphic analysis, combined with detrital apatite fission‐track thermochronology from a ～6200‐m‐thick Miocene to Pliocene stratigraphic section in the Angastaco basin, document the late Eocene to late Pliocene exhumation history of source regions along the eastern border of the Puna (Eastern Cordillera (EC)) as well as the construction of orographic barriers along the southeastern flank of the Central Andes. Onset of exhumation of a source in the EC in late Eocene time as well as a rapid exhumation of the Sierra de Luracatao (in the EC) at about 20 Ma are recorded in the detrital sediments of the Angastaco basin. Sediment accumulation in the basin began ～15 Ma, a time at which the EC had already built sufficient topography to prevent Puna sourced detritus from reaching the basin. After ～13 Ma, shortening shifted eastward, exhuming ranges that preserve an apatite fission‐track partial annealing zone recording cooling during the late Cretaceous rifting event. Facies changes and fossil content suggest that after 9 Ma, the EC constituted an effective orographic barrier that prevented moisture penetration into the plateau. Between 3.4 and 2.4 Ma, another orographic barrier was uplifted to the east, leading to further aridification and pronounced precipitation gradients along the mountain front. This study emphasizes the important role of tectonics in the evolution of climate in this part of the Andes.  相似文献   

Numerical models of magnetic reconnection     

Manfred Scholer 《地球物理与天体物理流体动力学》2013,107(1-4):51-68

  相似文献   

The feedback control cycle as regulator of past and future mineral supply     

Friedrich-W. Wellmer  Manfred Dalheimer 《Mineralium Deposita》2012,47(7):713-729

Mineral supply is controlled by a feedback mechanism. When there is a shortage of a commodity in a market economy, prices will rise, triggering this mechanism. The expectation of high financial returns will encourage inventiveness and creativity in the quest for new solutions. On the supply side, for primary resources, the appropriate response is to cut losses in the mining process, to lower the cut-off grade, to improve recoveries in the beneficiation and smelting processes, to expand existing production facilities, and to discover and bring into production new deposits. For secondary resources, the key to increasing the supply lies in improving recycling rates by better technology, reprocessing lower-grade scrap which becomes economic because of increased prices, and reducing downgrading to optimize the usefulness of secondary materials. On the demand side, implementation of new and more efficient processes, development of substitution technologies, material savings, and the invention of entirely new technologies that fulfill the same function without the need of using the scarce and suddenly more expensive material are effective reactions to a price rise. The effectiveness of this self-regulating mechanism can be shown by examples of historical price peaks of metals, such as Mo, Co, and Ta, and the current rare earth elements peak. Concerning supply from secondary resources, a model is developed in order to determine how far the supply from this resource domain can be achieved and how the recycling rate is influenced by growth rate and lifetime. The feedback control cycle of mineral supply is influenced on the demand side by ever shorter life cycles, by products getting more complex with ever more elements involved in their production, and by an increase in element dispersion. All these factors have an immediate effect on the feasibility of sourcing raw materials from the technosphere. The supply side of primary materials is influenced by increasing lead times for new production and by relatively low flexibility in responding to changing demand.  相似文献   

Reply to Preusser et al. on Frechen et al. “Late Pleistocene fluvial dynamics in the Hochrhein Valley in the upper Rhine Graben: chronological frame”     

Manfred Frechen  Dietrich Ellwanger  Matthias Hinderer  J?rg L?mmermann-Barthel  Inge Neeb  Astrid Techmer 《International Journal of Earth Sciences》2012,101(1):389-392

  相似文献   

2021 JGS best paper award and the editors’ choice paper volume 24(1)     

Fischer  Manfred M.  Paez  Antonio  Staufer-Steinnocher  Petra 《Journal of Geographical Systems》2022,24(1):1-4

Journal of Geographical Systems -  相似文献   

Poverty tourism: theoretical reflections and empirical findings regarding an extraordinary form of tourism   总被引：1，自引：0，他引：1  

Manfred Rolfes 《GeoJournal》2010,75(5):421-442

During the mid-1990s, a new form of tourism was established in metropolises of several developing countries or emerging nations. This type of tourism consists in visits to the most disadvantaged parts of the respective city. Poverty tours or slum tours are offered on a relatively large scale in the South African cities of Johannesburg and Cape Town, Rio de Janeiro in Brazil, as well as in Indian metropolises, to name some important examples. The target group of these tours consists primarily of international tourists. It is estimated that 40,000 such tourists visit favelas in Rio de Janeiro each year, around 300,000 the townships in Cape Town. This contribution refers to and comments on these developments and insights regarding poverty tourism or slumming, based on empirical research and experiences in South Africa, Brazil, and India. It will be shed light on the phenomenon from an observational-theoretical perspective. It is aimed to open a discussion on the ways poverty tours or slumming observes and simultaneously programmatically charges poverty. And, it will be considered in which way poverty tourism is observed.  相似文献   

Early Holocene environmental history of sunken landscapes: pollen, plant macrofossil and geochemical analyses from the Borkum Riffgrund, southern North Sea     

Steffen Wolters  Manfred Zeiler  Friederike Bungenstock 《International Journal of Earth Sciences》2010,99(8):1707-1719

A vibrocore from the sea floor of the southern North Sea provides a ~1,500-year record of early Holocene vegetation history and mire development in a landscape now 33 m below sea-level. Pollen, plant macrofossil and geochemical analyses of an AMS ¹⁴C dated sand–peat–marine mud sequence document the paludification on Pleistocene sands ~10,700 cal BP, the subsequent development of eutraphentic carr vegetation and the gradual inundation by the transgressing sea ~9,350 cal BP. Pinus–Corylus woodland prevailed on terrestrial grounds after hazel had immigrated ~10,700 cal BP. Salix dominated the carr vegetation throughout 1,300 years of peat formation, because Alnus did not spread in the Borkum Riffgrund area until 9,300 BP. Brackish reed vegetation with Phragmites established after inundation and siliciclastic marine sediments were being deposited. This article also examines the detection and suitability of key horizons indicative of marine influence. XRF-Scanning provides the most detailed results in the briefest possible time to pinpoint spectra best suitable for AMS ¹⁴C dating of classical key horizons such as start of peat formation and transgressive contact. The combined application of botanical and geochemical methods allows determining new key horizons indicative of marine influence, namely the earliest marine inundation and the onset of sea-level influence on coastal ground water level.  相似文献   

Revealing the coastal event-history of the Andaman Islands (Bay of Bengal) during the Holocene using radiocarbon and OSL dating   总被引：1，自引：0，他引：1  

Alexander Kunz  Manfred Frechen  Ramachandran Ramesh  Brigitte Urban 《International Journal of Earth Sciences》2010,99(8):1741-1761

Earthquakes that trigger tsunamis are of great geological, ecological and socio-economic importance. The knowledge of the recurrence interval of these events will give information about the hazard for a region. Coastal sediments on the Andaman Islands located in the eastern Bay of Bengal were investigated to find evidence for palaeotsunamis and palaeoearthquakes. Fieldwork was conducted on Red Skin Island and North Cinque Island, south of South Andaman. Sediment material from event-layers was dated by optically stimulated luminescence and radiocarbon dating method. The results show evidence possibly for one earthquake at about 1,000 or 3,000 years before the present together with deposits from possible tsunamis and storms. The complex pattern of co- and post-seismic uplift and subsidence of the Andaman Islands is reflected in the investigated sections and made it possible to reconstruct an event-history for the last 3,000 years.  相似文献   

Distribution of uranium in German bottled and tap water     

Manfred Birke  Uwe Rauch  Hans Lorenz  Robert Kringel 《Journal of Geochemical Exploration》2010

The results presented in this paper on uranium in bottled and tap water were determined within the scope of the project “European Groundwater Geochemistry: Bottled Water” of the Geochemistry Expert Group of EuroGeoSurveys. The analyses of bottled water provide an inexpensive approach to obtain information about European groundwater geochemistry. For this study, the uranium concentrations in 1785 European mineral water samples were analyzed by ICP–QMS in the BGR laboratories. The dataset is used to obtain a first impression about natural concentration levels and variation of uranium in groundwater (and bottled water) at the German and European scale.  相似文献   

Reply to the comment “Bottled drinking water: Water contamination from bottle materials (glass,hard PET,soft PET), the influence of colour and acidification” by Hayo Müller-Simon     

Clemens Reimann  Manfred Birke  Peter Filzmoser 《Applied Geochemistry》2010

  相似文献