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991.
992.
Johannes F. Kruiger Vedran Kasalica Rogier Meerlo Anna‐Lena Lamprecht Enkhbold Nyamsuren Simon Scheider 《Transactions in GIS》2021,25(1):424-449
Loose programming enables analysts to program with concepts instead of procedural code. Data transformations are left underspecified, leaving out procedural details and exploiting knowledge about the applicability of functions to data types. To synthesize workflows of high quality for a geo‐analytical task, the semantic type system needs to reflect knowledge of geographic information systems (GIS) at a level that is deep enough to capture geo‐analytical concepts and intentions, yet shallow enough to generalize over GIS implementations. Recently, core concepts of spatial information and related geo‐analytical concepts were proposed as a way to add the required abstraction level to current geodata models. The core concept data types (CCD) ontology is a semantic type system that can be used to constrain GIS functions for workflow synthesis. However, to date, it is unknown what gain in precision and workflow quality can be expected. In this article we synthesize workflows by annotating GIS tools with these types, specifying a range of common analytical tasks taken from an urban livability scenario. We measure the quality of automatically synthesized workflows against a benchmark generated from common data types. Results show that CCD concepts significantly improve the precision of workflow synthesis. 相似文献
993.
Cryptotephras in the Lateglacial ICDP Dead Sea sediment record and their implications for chronology
Ina Neugebauer Daniela Müller Markus J. Schwab Simon Blockley Christine S. Lane Sabine Wulf Oona Appelt Achim Brauer 《Boreas: An International Journal of Quaternary Research》2021,50(3):844-861
Due to a lack of visible tephras in the Dead Sea record, this unique palaeoenvironmental archive is largely unconnected to the well-established Mediterranean tephrostratigraphy. Here we present first results of the ongoing search for cryptotephras in the International Continental Drilling Program (ICDP) sediment core from the deep Dead Sea basin. This study focusses on the Lateglacial (~15–11.4 cal. ka BP), when Lake Lisan – the precursor of the Dead Sea – shrank from its glacial highstand to the Holocene low levels. We developed a glass shard separation protocol and counting procedure that is adapted to the extreme salinity and sediment recycling of the Dead Sea. Cryptotephra is abundant in the Dead Sea record (up to ~100 shards cm-3), but often glasses are physically and/or chemically altered. Six glass samples from five tephra horizons reveal a heterogeneous geochemical composition, with mainly rhyolitic and some trachytic glasses potentially sourced from Italian, Aegean and Anatolian volcanoes. Most shards likely originate from the eastern Anatolian volcanic province and can be correlated using major element analyses with tephra deposits from swarm eruptions of the Süphan Volcano ~13 ka BP and with ashes from Nemrut Volcano, presumably the Lake Van V-16 volcanic layer at ~13.8 ka BP. In addition to glasses that match the TM-10-1 from Lago Grande di Monticchio (15 820±790 cal. a BP) tentatively correlated with the St. Angelo Tuff of Ischia, we further identified a cryptotephra with glass analyses which are chemically identical with those of the PhT1 tephra in the Philippon peat record (13.9–10.5 ka BP), and also a compositional match for the glass analyses of the Santorini Cape Riva Tephra (Y-2 marine tephra, 22 024±642 cal. a BP). These first results demonstrate the great potential of cryptotephrochronology in the Dead Sea record for improving its chronology and connecting the Levantine region to the Mediterranean tephra framework. 相似文献
994.
Acta Geotechnica - At high values of degree of saturation, the apparent soil water retention curve (SWRC) measured in a wetting test in the laboratory may differ from the true SWRC, because of the... 相似文献
995.
996.
997.
Traces of historical tropical cyclones and tsunamis in the Ashburton Delta (north‐west Australia) 下载免费PDF全文
Simon Matthias May Dominik Brill Max Engel Anja Scheffers Anna Pint Stephan Opitz Volker Wennrich Peter Squire Dieter Kelletat Helmut Brückner 《Sedimentology》2015,62(6):1546-1572
Although the north‐western coast of Western Australia is highly vulnerable to tropical cyclones and tsunamis, little is known about the geological imprint of historic and prehistoric extreme wave events in this particular area. Despite a number of site‐specific difficulties such as post‐depositional changes and the preservation potential of event deposits, both tropical cyclones and tsunamis may be inferred from the geomorphology and the stratigraphy of beach ridge sequences, washover fans and coastal lagoons or marshes. A further challenge is the differentiation between tsunami and storm deposits in the geological record, particularly where modern deposits and/or historical reports on the event are not available. This study presents a high‐resolution sedimentary record of washover events from the Ashburton River delta (Western Australia) spanning approximately the last 150 years. A detailed characterization of event deposits is provided, and a robust chronostratigraphy for the investigated washover sequence is established based on multi‐proxy sediment analyses and optically stimulated luminescence dating. Combining sedimentological, geochemical and high‐resolution optically stimulated luminescence data, event layers are assigned to known historical events and tropical cyclone deposits are separated from tsunami deposits. For the first time, the 1883 Krakatoa and 1977 Sumba tsunamis are inferred from sedimentary records of the north‐western part of Western Australia. It is demonstrated that optically stimulated luminescence applied in coastal sedimentary archives with favourable luminescence characteristics can provide accurate chronostratigraphies even on a decadal timescale. The results contribute to the data pool of tropical cyclone and tsunami deposits in Holocene stratigraphies; however, they also demonstrate how short‐lived sediment archives may be in dynamic sedimentary environments. 相似文献
998.
Norbert Simon Michael Crozier Mairead de Roiste Abdul Ghani Rafek Rodeano Roslee 《Singapore journal of tropical geography》2015,36(1):98-111
This study assesses the influence of development on landslide occurrences in a rapidly developing area, Kota Kinabalu in Sabah Malaysia, across three assessment years (1978, 1994 and 2010). Two development indicators, land use and road density, were used to measure the influence of development on landslide occurrence. Land use was classified into four categories (barren, forest, developed and other), and road density was classified into low (< 50 m/40 000 m2), moderate (50–150 m/40 000 m2) and high (> 150 m/40 000 m2). Landslide density analysis was used to calculate the concentration of landslide for the different land use and road density categories. The number of landslides in developed areas increased from 19 landslides/100 km2 in 1978, to 29 landslides/100 km2 in 1994 and to 50 landslides/100 km2 in 2010, mirroring an increase in land use for development purposes from 8 per cent in 1978 to 27 per cent in 2010. Landslide density also gradually increased in the high road density class from 10 landslides/100 km2 in 1978, to 30 landslides/100 km2 in 1994 and 62 landslides/100 km2 in 2010. These results show that road construction activities influence landslide occurrences. 相似文献
999.
The Basement Sill is part of the Ferrar Large Igneous Provinceexposed in the McMurdo Dry Valleys, Antarctica. The sill is330 m thick in the Bull Pass area and 450 + m thick in the Daisarea, 12 km to the west, and is characterized by phenocryst-freelower and upper margins and an orthopyroxene-rich central tongue(opx 15 mm in size). Halogen variations in apatite froma suite of samples collected along vertical transects throughthe sill were examined to evaluate the process of crystallization-induceddegassing (i.e. second boiling) and its effects on magma chemistry.Apatite grains from any given sample are generally unzoned withrespect to Cl and F concentrations, but may vary by 2030mol% in the halogen site between grains. Overall average Cl/Fmass ratios increase with height from the lower margin to thecenter of the sill, and then decrease to near zero towards thetop margin where the rocks are relatively oxide-rich. The Cl/Ftrend parallels those of bulk MgO and grain size. The uppermargin contains abundant mafic pegmatoids and the apatite inthese segregations has lower Cl/F ratios compared with thatin the host-rocks, although REE show no measurable difference.Numerical modeling illustrates that a cooling and crystallizingsill initially develops two separate vapor-saturated zones atthe lower and upper margins owing to the irreversible heat lossto the cooler country rock. Vapor separating from the lowerzone migrates upward into hotter silicate liquid, where it isresorbed, thus increasing the Cl/F mass ratio of the liquid.This process leads to saturation and precipitation of apatitefrom the liquid with a higher Cl/F ratio than would otherwiseoccur. Volatile enrichment can also aid compaction and graingrowth in the central part of the sill. In contrast, the relativelyFe-rich, Cl-poor nature of the upper zone rocks suggests thatthese rocks may have crystallized from more evolved, degassedsilicate liquid, possibly compacted out of the underlying crystalmush. In addition, as vapor sourced from the lower and centralparts of the sill ascends into the cooler upper zone of thesill, the vapor may be localized (along with late interstitialsilicate liquid) to form pegmatoids at temperatures at whichCl is less favored in apatite and can be leached from existingapatite by the ascending vapor, the latter causing the observeddecrease in the Cl/F mass ratio of apatite in the (evolved)pegmatoids. KEY WORDS: Ferrar Igneous Province; halogens; fluid; apatite 相似文献
1000.
Simon Nina S. C.; Carlson Richard W.; Pearson D. Graham; Davies Gareth R. 《Journal of Petrology》2007,48(3):589-625
A detailed petrological and geochemical study of low-temperatureperidotite xenoliths from Kimberley and northern Lesotho ispresented to constrain the processes that led to the magmaphileelement depletion of the Kaapvaal cratonic lithospheric mantleand its subsequent re-enrichment in Si and incompatible traceelements. Whole-rocks and minerals have been characterized forReOs isotope compositions, and major and trace elementconcentrations, and garnet and clinopyroxene for LuHfand SmNd isotope compositions. Most samples are characterizedby Archaean Os model ages, low Al, Fe and Ca contents, highMg/Fe, low Re/Os, very low (< 0·1 x chondrite) heavyrare earth element (HREE) concentrations and a decoupling betweenNd and Hf isotope ratios. These features are most consistentwith initial melting at 3·2 Ga followed by metasomatismby hydrous fluids, which may have also caused additional meltingto produce a harzburgitic residue. The low HREE abundances ofthe peridotites require that extensive melting occurred in thespinel stability field, possibly preceded by some melting inthe presence of garnet. Fractional melting models suggest that30% melting in the spinel field or 20% melting in the garnetfield followed by 20% spinel-facies melting are required toexplain the most melt-depleted samples. Garnet NdHf isotopecharacteristics indicate metasomatic trace element enrichmentduring the Archaean. We therefore suggest a model includingshallow ridge melting, followed by metasomatism of the Kaapvaalupper mantle in subduction zones surrounding cratonic nuclei,probably during amalgamation of smaller pre-existing terranesin the Late Archaean (2·9 Ga). The fluid-metasomatizedresidua have subsequently undergone localized silicate meltinfiltration that led to clinopyroxene ± garnet enrichment.Calculated equilibrium liquids for clinopyroxene and their HfNdisotope compositions suggest that most diopside in the xenolithscrystallized from an infiltrating kimberlite-like melt, eitherduring Group II kimberlite magmatism at 200110 Ma (Kimberley),or shortly prior to eruption of the host kimberlite around 90Ma (northern Lesotho). KEY WORDS: Kaapvaal craton; lithospheric mantle; metasomatism; NdHf isotopes; ReOs isotopes 相似文献