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151.
In the Kor-, Saualpe and Pohorje regions of the Eastern Alps eclogite bodies occur within metapelitic gneisses. The bodies are between 1 meter and several hundreds of meters in size and some of them were defined by Haüy (1822) as the type locality for the rock type “eclogite”. A growing body of petrological work has documented the metamorphic evolution of the metapelites surrounding the eclogites. However, few phase diagrams have been constructed for the eclogite bodies themselves. Here we use recently available activity models for amphiboles to present new thermodynamic pseudosections for the Hohl locality of the Koralpe eclogites. We show that this eclogite reached peak conditions in a narrow PT field obliquely oriented in PT space between 16.5 and 20.5 kbar and 620°C to 720°C and that its metamorphic evolution was likely to have occurred under water saturated conditions. We conclude that eclogite and the surrounding metapelites have certainly undergone the same metamorphic peak in Eo-alpine time. Comparison of our results with different PT estimates on the eclogite from Pohorje, suggest that a PT gradient from Koralpe to Pohorje is likely. 相似文献
152.
Hayfaa Abdul Aziz Madelaine B?hme Alexander Rocholl Jerome Prieto Jan R. Wijbrans Valerian Bachtadse Albert Ulbig 《International Journal of Earth Sciences》2010,99(8):1859-1886
A detailed integrated stratigraphic study (biostratigraphy and magnetostratigraphy) was carried out on five sections from
the western part of the Bavarian Upper Freshwater Molasse of the North Alpine Foreland Basin (NAFB), greatly improving the
chronostratigraphy of these sediments. The sections belong to the lithostratigraphic units Limnische Untere Serie (UL) and Fluviatile Untere Serie (UF) and contain 19 (mostly new) small-mammal bearing levels, significantly refining the local biostratigraphy. Radiometric
ages obtained from glass shards from tuff horizons are used together with the biostratigraphic information for constructing
and confirming the magnetostratigraphic correlation of the studied sections to the Astronomical Tuned Time Scale (ANTS04;
Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). This correlation implies that the UL lithostratigraphic
unit corresponds to the latest Ottnangian and the Early Karpatian, whereas the UF corresponds to the Karpatian and the Early
Badenian. This indicates that the Brackish- to Freshwater Molasse transition already occurred during the late Ottnangian.
The pre-Riesian hiatus occurred in the latest Karpatian and lower Early Badenian in Eastern Bavaria and Bohemia and in the
Late Karpatian and earliest Badenian in Western Bavaria. The geochemical and Ar–Ar data of volcanic ashes suggest that highly
evolved silicic magmas from a single volcano or volcanic center, characterized by a uniform Nd isotopic composition, erupted
repetitively over the course of at least 1.6 Myr. Three phases of eruptive activity were identified at 16.1 ± 0.2 Ma (Zahling-2),
15.6 ± 0.4 Ma (Krumbad), and 14.5 ± 0.2 Ma (Heilsberg, Hegau). The correlation of the local biostratigraphic zonation to the
ANTS04 enables further the characterization of both the Ottnangian–Karpatian and Karpatian–Badenian boundaries in the NAFB
by small-mammal biostratigraphy. According to these results the Ottnangian–Karpatian boundary is contemporaneous with the
first appearance datum of Megacricetodon
bavaricus (in the size of the type population) and the first common occurrence of Keramidomys thaleri, whereas Ligerimys florancei, Melissiodon dominans and Prodeinotherium aff. bavaricum have been already disappeared during the late Ottnangian. The Karpatian–Badenian boundary is characterized by a significant
size increase of the large Megacricetodon lineage and possibly a (re-)immigration of Prodeinotherium bavaricum. 相似文献
153.
The existing procedures for the selection of runout model parameters from back-analyses do not allow integrating different
types of runout criteria and generally lack a systematic approach. A new method based on receiver operating characteristic
(ROC) analyses and aimed at overcoming these limitations is herein proposed. The method consists of estimating discrete classifiers
for every runout simulation associated with a set of model parameters. The set of parameters that yields the best prediction
is selected using ROC metrics and space. The procedure is illustrated with the back-analyses of a rainfall-triggered debris
flow that killed 300–500 people in the Metropolitan Area of San Salvador in 1982. The selected model parameters are used to
estimate forward predictions for scenarios that correspond to different return periods. The proposed procedure may be useful
in the assessment of areas potentially affected by landslides. In turn, this information can be used in the production or
updating of land use plans and zonations, similar to that currently being carried out by the Office for Urban Planning of
the Metropolitan Area of San Salvador in El Salvador. 相似文献
154.
Worldwide, the ammonoid genus Prolobites is only known from a few localities, and from these fossil beds almost all of the specimens are adults as shown by the presence
of a terminal growth stage. This is in marked contrast to the co-occurring ammonoid genera such as Sporadoceras, Prionoceras, and Platyclymenia. Size distribution of specimens of Prolobites from three studied localities show that, unlike in the co-occurring ammonoid species, most of the material belongs to adult
individuals. The morphometric analysis of Prolobites delphinus (Sandberger & Sandberger 1851) demonstrates the intraspecific variability including variants with elliptical coiling and that dimorphism is not detectable.
The Prolobites material shows close resemblance to spawning populations of Recent coleoids such as the squid Todarodes filippovae Adam
1975. Possible mass spawning events are discussed in the context of the size distribution and limited geographic range of Prolobites. Finally, the potential fecundity and brooding behaviour of Prolobites is hypothesized using the examples of post spawning egg care in Recent coleoids. 相似文献
155.
Jürgen M. Reitner Wilfried Gruber Alexander Römer Rainer Morawetz 《Swiss Journal of Geoscience》2010,103(3):385-405
We present a study of the inneralpine basin of Hopfgarten focused on the analysis of basin fill in order to reveal its formation
in relation to paleo-ice flow and tectonics. The study is based on geological mapping as well as seismic (reflection and refraction)
and geoelectrical surveys. The oldest sequence in the basin, identified by seismic stratigraphy at 400 m below surface, consists
of coarse grained sediments of supposedly Oligocene to Miocene age, which subsided along faults linked to the Inn fault. Three
superimposed sequences, each displaying baselaps in contact with a subglacially formed unconformity and sigmoid foresets,
show pleniglacial conditions followed by a glaciolacustrine environment. The uppermost of these three sequences lies on top
of last glacial maximum till (LGM; Würmian Pleniglacial; MIS 2) and represents Termination I. The middle sequence is classified
as Termination II following the Rissian Pleniglacial (MIS 6). The oldest glacial sequence cannot be constrained chronostratigraphically
but might correlate with Termination V following the major glaciation of MIS 12. Limited glacial erosion during the LGM occurred
only during the ice build-up phase. Further overdeepening was impeded due to topographic barrier and mutual blockades of glaciers
within this highly dissected landscape. The occurrence and relative timing of the impediment was controlled by the onset of
transfluences and thus by the altitude of coles. The higher amount of overdeepening during older glacial periods is explained
by longer phases of free ice advance in the ice build up phase due to higher transfluences routes at that time. Thus, the
preservation of older Pleistocene sequences within the basin may be the result of the lowering of watersheds from one glaciation
to the next. Our model of an inverse relationship between glacial shaping of the surface and the subsurface may apply to similar
Alpine landscapes as well. 相似文献
156.
Thilo Wrona Alexander C. Whittaker Rebecca E. Bell Robert L. Gawthorpe Haakon Fossen Christopher A.-L. Jackson Marit Stokke Bauck 《Basin Research》2023,35(2):744-761
Our understanding of continental rifting is, in large parts, derived from the stratigraphic record. This record is, however, incomplete as it does not often capture the geomorphic and erosional signal of rifting. New 3D seismic reflection data reveal a Late Permian-Early Triassic landscape incised into the pre-rift basement of the northern North Sea. This landscape, which covers at least 542 km2, preserves a drainage system bound by two major tectonic faults. A quantitative geomorphic analysis of the drainage system reveals 68 catchments, with channel steepness and knickpoint analysis of catchment-hosted palaeo-rivers showing that the landscape preserved a >2 Myr long period of transient tectonics. We interpret that this landscape records a punctuated uplift of the footwall of a major rift-related normal fault (Vette Fault) at the onset of rifting. The landscape was preserved by a combination of relatively rapid subsidence in the hangingwall of a younger fault (Øygarden Fault) and burial by post-incision sediments. As such, we show how and why erosional landscapes are preserved in the stratigraphic record, and how they can help us understand the tectono-stratigraphic evolution of ancient continental rifts. 相似文献
157.
Hannes Römer Jens Kersten Ralph Kiefl Stefan Plattner Alexander Mager Stefan Voigt 《International journal of geographical information science》2014,28(4):682-699
A critical requirement for an effective and coordinated response by public entities tasked with management, security, and relief during large-scale public events or natural disasters is the availability of current situational information. However, today there is a lack of comprehensive operational systems allowing a near-real-time (NRT) collection, visualization, and provision of situational information for larger areas. In this study a methodological framework is proposed, which allows an NRT extraction and visualization of situational information based on aerial image acquisition. The framework combines digital image analysis using a generic supervised information extraction approach based on statistical modeling with a downstream web-based visualization component realized through an automatic update of web services. Even though being applicable for different scenarios, the workflow will be demonstrated for the specific use-case of a NRT monitoring of open spaces including assembly and parking areas. Compared to other approaches, image analysis results indicate a high robustness and a low demand for computational power sources (7 seconds per image). Due to a high degree of automation, the proposed workflow contributes to a NRT ‘end-to-end’ monitoring system, which was developed within the VABENE (German acronym for ‘traffic management under large-scale public events and disaster conditions’) project covering all parts from the acquisition of raw aerial imagery to the dissemination of information products to end-users. 相似文献
158.
Alexander Gocht Norbert Röder 《International journal of geographical information science》2014,28(9):1744-1764
In Germany, a county-resolution data set that consists of 35 land-use and animal-stock categories has been used extensively to assess the impact of agriculture on the environment. However, because such environmental effects as emission or nutrient surplus depend on the location, even a county resolution might produce misleading results. The aim of this article is to propose a Bayesian approach which combines two sorts of information, with one being treated as defining the prior and the other the data to form a posterior, used to estimate a data set at a municipality resolution. We define the joint prior density function based on (i) remote sensing data, thus accounting for differences in county data and missing data at the municipality level, and (ii) the results of a cluster analysis that was previously applied to the micro-census, whereas the data are defined by official statistics at the county level. This approach results in a fairly accurate data set at the municipality level. The results, using the proposed method, are validated by the national research data centre by comparing the estimates to actual observations. The test statistics presented here demonstrate that the proposed approach adequately estimates the production activities. 相似文献
159.
Alexander Hohl Ross K. Meentemeyer 《International journal of geographical information science》2014,28(8):1626-1641
Understanding the diverse ways that landscape connectivity influences the distribution of microbial species is central to managing the spread and persistence of numerous biological invasions. Here, we use geospatial analytics to examine the degree to which the hydrologic connectivity of landscapes influences the transport of passively dispersed microbes, using the invasive plant pathogen Phytophthora ramorum as a case study. Pathogen occurrence was analyzed at 280 stream baiting stations across a range of watersheds – exposed to variable inoculum pressure – in California over a 7-year period (2004–2010). Using logistic regression, we modeled the probability of pathogen occurrence at a baiting station based on nine environmental variables. We developed a novel geospatial approach to quantify the hydrologic connectivity of host vegetation and inoculum pressure derived from least cost distance analyses in each watershed. We also examined the influence of local environmental conditions within the immediate neighborhood of a baiting station. Over the course of the sampling period, the pathogen was detected at 67 baiting stations associated with coastal watersheds with mild climate conditions, steep slopes, and higher levels of inoculum pressure. At the watershed scale, hydrologic landscape connectivity was a key predictor of pathogen occurrence in streams after accounting for variation in climate and exposure to inoculum. This study illustrates a geospatial approach to modeling the degree to which hydrologic systems play a role in shaping landscape structures conducive for the transport of passively dispersed microbes in heterogeneous watersheds. 相似文献
160.
Anne-Cathrin Wölfl Chai Heng Lim H. Christian Hass Sebastian Lindhorst Gabriela Tosonotto Karsten Alexander Lettmann Gerhard Kuhn Jörg-Olaf Wolff Doris Abele 《Geo-Marine Letters》2014,34(5):435-446
Marine habitats worldwide are increasingly pressurized by climate change, especially along the Antarctic Peninsula. Well-studied areas in front of rapidly retreating tidewater glaciers like Potter Cove are representative for similar coastal environments and, therefore, shed light on habitat formation and development on not only a local but also regional scale. The objective of this study was to provide insights into habitat distribution in Potter Cove, King George Island, Antarctica, and to evaluate the associated environmental processes. Furthermore, an assessment concerning the future development of the habitats is provided. To describe the seafloor habitats in Potter Cove, an acoustic seabed discrimination system (RoxAnn) was used in combination with underwater video images and sediment samples. Due to the absence of wave and current measurements in the study area, bed shear stress estimates served to delineate zones prone to sediment erosion. On the basis of the investigations, two habitat classes were identified in Potter Cove, namely soft-sediment and stone habitats that, besides influences from sediment supply and coastal morphology, are controlled by sediment erosion. A future expansion of the stone habitat is predicted if recent environmental change trends continue. Possible implications for the Potter Cove environment, and other coastal ecosystems under similar pressure, include changes in biomass and species composition. 相似文献