Modeling land suitability/capability using fuzzy evaluation     

Fang Qiu  Bryan Chastain  Yuhong Zhou  Caiyun Zhang  Harini Sridharan 《GeoJournal》2014,79(2):167-182

Modeling the suitability of land to support specific land uses is an important and common GIS application. Three classic models, specifically pass/fail screening, graduated screening and weighted linear combination, are examined within a more general framework defined by fuzzy logic theory. The rationale underlying each model is explained using the concepts of fuzzy intersections, fuzzy unions and fuzzy averaging operations. These fuzzy implementations of the three classic models are then operationalized and used to analyze the distribution of kudzu in the conterminous United States. The fuzzy models achieve better predictive accuracies than their classic counterparts. By incorporating fuzzy suitability membership of environment factors in the modeling process, these fuzzy models also produce more informative fuzzy suitability maps. Through a defuzzification process, these fuzzy maps can be converted into conventional maps with clearly defined boundaries, suitable for use by individuals uncomfortable with fuzzy results.  相似文献   

Determination of the Tin Stable Isotopic Composition in Tin‐bearing Metals and Minerals by MC‐ICP‐MS          下载免费PDF全文

Gerhard Brügmann  Daniel Berger  Ernst Pernicka 《Geostandards and Geoanalytical Research》2017,41(3):437-448

This study uses MC‐ICP‐MS for the precise analysis of the stable tin isotopic composition in ore minerals of tin (cassiterite, stannite), tin metal and tin bronze. The ultimate goal is to determine the provenance of tin in ancient metal objects. We document the isotope compositions of reference materials and compare the precision of different isotope ratios and the accuracy of different procedures of mass fractionation correction. These data represent a base with which isotopic data of future studies can be directly compared. The isotopic composition of cassiterite and stannite can be determined after reduction to tin metal and bronze, respectively. Both metals readily dissolve in HCl, but while the solutions of tin metal can be directly measured, the bronze solutions must be purified with an anion exchanger. The correction of the mass bias is best performed with an internal Sb standard and an empirical regression method. A series of Sn isotope determinations on commercially available mono‐element Sn solutions as well as reference bronze materials and tin minerals show fractionations ranging from about ?0.09‰ to 0.05‰/amu. The combined analytical uncertainty (2s) was determined by replicate dissolutions of reference materials of bronze (BAM 211, IARM‐91D) and averages at about 0.005‰/amu.  相似文献   

Geochemistry and isotope systematics of calc-alkaline volcanic rocks from the Saar-Nahe basin (SW Germany) – implications for Late-Variscan orogenic development     

Stefanie S. Schmidberger  Ernst Hegner 《Contributions to Mineralogy and Petrology》1999,135(4):373-385

Late Carboniferous (300–290 Ma) calc-alkaline basalts, andesites, and rhyolites typical of volcanic arc settings occur in the intermontane Saar-Nahe basin (SW Germany) within the Variscan orogenic belt. The volcanic rock suite was emplaced under a regime of tensional tectonics during orogenic collapse and its origin has been explained by melting of mantle and crust in the course of limited lithospheric rifting. We report major, trace and rare-earth-element data (REE), and Nd-Pb-Sr-O isotope ratios for a representative sample suite, which are fully consistent with an origin closely related to plate subduction. Major and trace element data define continuous melt differentiation trends from a precursor basaltic magma involving fractional crystallization of olivine, pyroxene, plagioclase, and magnetite typical of magma evolution in a volcanic arc. This finding precludes an origin of the andesitic compositions by mixing of mafic and felsic melts as can be expected in anorogenic settings. The mafic samples have high Mg numbers (Mg# = 65–73), and high Cr (up to 330 ppm) and Ni (up to 200 ppm) contents indicating derivation from a primitive parental melt that was formed in equilibrium with mantle peridotite. We interpret the geochemical characteristics of the near-primary basalts as reflecting their mantle source. The volcanic rocks are characterized by enrichment in the large ion lithophile elements (LILE), negative Nb and Ti, and positive Pb anomalies relative to the neighboring REE, suggesting melting of a subduction-modified mantle. Initial _Nd values of −0.7 to −4.6, Pb, and ⁸⁷Sr/⁸⁶Sr_(t) isotope ratios for mafic and felsic volcanics are similar and indicate partial melting of an isotopically heterogeneous and enriched mantle reservoir. The enrichment in incompatible trace elements and radiogenic isotopes of a precursor depleted mantle may be attributed to addition of an old sedimentary component. The geochemical characteristics of the Saar-Nahe volcanic rocks are distinct from typical post-collisional rock suites and they may be interpreted as geochemical evidence for ongoing plate subduction at the margin of the Variscan orogenic belt not obvious from the regional geologic context. Received: 3 August 1998 / Accepted: 2 January 1999  相似文献   

After the nursery: Regional and broad-scale movements of sharks tagged in the Caribbean     

Bryan Legare  Bryan DeAngelis  Gregory Skomal 《Marine Ecology》2020,41(5):e12608

Broad-scale movements (10s–100s km) of highly migratory species, such as sharks, present unique management challenges as fish migrate across international boundaries, thereby exposing them to different levels of anthropogenic pressure. Lemon sharks and blacktip sharks are well-studied throughout their range in the western North Atlantic, but broad-scale movements in the Caribbean region are largely unknown. Utilizing 10 years (2004–2014) of acoustic and conventional tagging data, this study presents the post-nursery movements of young of the year (YOY) and juvenile blacktip (n = 198) and lemon (n = 130) sharks tagged in the United States Virgin Islands (USVI). A total of five (2.5%) blacktip sharks were recaptured by recreational and commercial fishers in the greater Caribbean and as far north as the southeastern coast of the United States, moving between 2 and 2,200 km and crossing a minimum of six international boundaries. Of the acoustically tagged blacktip (n = 88) and lemon (n = 45) sharks, 28 (32%) and 16 (24%), respectively, were detected outside the boundaries of the nursery area in which they were tagged, dispersing throughout the USVI territory; blacktip sharks were acoustically detected beyond territorial waters as far as Florida, United States (1,881 km). Both species transited through local marine protected areas but did not establish residency resulting in little protection. This is the first study to examine connectivity between blacktip shark populations of the USVI and the east coast of the United States.  相似文献   

Thinking outside the polygon: a study of tornado warning perception outside of warning polygon bounds     

Krocak  Makenzie J.  Ernst  Sean  Allan  Jinan N.  Wehde  Wesley  Ripberger  Joseph T.  Silva  Carol L.  Jenkins-Smith  Hank C. 《Natural Hazards》2020,102(3):1351-1368

When the National Weather Service (NWS) issues a tornado warning, the alert is rapidly and widely disseminated to individuals in the general area of the warning. Historically, the assumption has been that a false-negative warning perception (i.e., when someone located within a warning polygon does not believe they have received a tornado warning) carries a higher cost than a false-positive warning perception (i.e., when someone located outside the warning area believes they have received a warning). While many studies investigate tornado warning false alarms (i.e., when the NWS issues a tornado warning, but a tornado does not actually occur), less work focuses on studying individuals outside of the warning polygon bounds who believe they received a warning (i.e., false-positive perceptions). This work attempts to quantify the occurrence of false-positive perceptions and possible factors associated with the rate of occurrence. Following two separate storm events, Oklahomans were asked whether they perceived a tornado warning. Their geolocated responses were then compared to issued warning polygons. Individuals closer to tornado warnings or within a different type of warning (e.g., a severe thunderstorm warning) are more likely to report a false-positive perception than those farther away or outside of other hazard warnings. Further work is needed to understand the rate of false-positive perceptions across different hazards and how this may influence warning response and trust in the National Weather Service.

  相似文献   

Enhanced nondestructive characterization of ordinary chondrites using complex magnetic susceptibility measurements     

P. Oliver  M. Ralchenko  C. Samson  R. E. Ernst  P. J. A. McCausland  G. F. West 《Meteoritics & planetary science》2018,53(3):433-447

Ordinary chondrites have previously been nondestructively characterized using bulk magnetic susceptibility, broadly reflecting their Fe-Ni alloy content. We seek to expand the information that can be recovered from magnetic susceptibility by using the University of Toronto Electromagnetic Induction Spectrometer (UTEMIS) to measure the complex magnetic susceptibility tensor of 20 ordinary chondrites samples in addition to 16 Gao–Guenie (H5) chondrites at 35 frequencies from 90 Hz to 64 kHz, at variable low applied field strengths <10 A m⁻¹. Following removal of the field-dependent component of susceptibility, frequency dependence, in- and out-of-phase components, and bulk magnetic susceptibility were interpreted. Most meteorites showed no frequency-dependent in-phase responses, but had a frequency-dependent out-of-phase response attributed to eddy currents induced in conductive minerals. Greater in- and out-of-phase frequency dependence correlated with lower fayalite content in olivine and was, in turn, inversely proportional to Fe-Ni alloy content. The uncertainty in the UTEMIS measurements ranges from approximately 0.05% for low-frequency in-phase measurements to a maximum of 3% for low-frequency out-of-phase measurements. This uncertainty level was far lower than the intra-meteorite variability for the Gao–Guenie suite suggesting inhomogeneity at scales of approximately 10 g.  相似文献   

Petrography,petrology and tectonic implications of Mitre Island,northern Fiji Plateau     

Peter A. Jezek  Wilfrad B. Bryan  Stephen E. Haggerty  H.Paul Johnson 《Marine Geology》1977,24(2):123-148

Mitre Island samples, Pliocene in age, can be classified together with Anuda samples, of unknown age, as island-arc basaltic andesites with tholeiitic tendencies. The presence of morphologically unusual iron—titanium oxides and of probably xenocrystic plagioclase suggest that at least part of the observed minerals crystallized in a magma chamber underlying the island. The samples apparently represent a mixture of magma fluid, cumulate plagioclase, pyroxene, and iron—titanium oxides which were ponded in a crater lava lake where they were reheated by subsequent eruptions. Many of them show symplectic magnetite formed by high-temperature oxidation of olivine. The morphological complexity and compositional homogeneity of the iron—titanium oxides cannot be explained at present.The presence of sulfide droplets inside olivine, magnetite and ilmenite crystals suggests a formation of an immiscible sulfide liquid in the magma chamber. Droplets of this liquid were overgrown by minerals crystallizing at that time and thus protected against oxidation during and after eruption.Mitre Island is a part of a currently inactive Vitiaz island arc associated in the past with a westward subduction of Pacific plate along the Vitiaz trench. Increased difficulty in subducting the large mass of the Pacific Border Plateau under the northern Fiji Plateau apparently produced counterclockwise rotation of the Vitiaz island arc. Oblique subduction was active until a steep angle was reached between the Vitiaz trench and the motion vector of the Pacific plate. Then a strike-slip fault developed in the Vitiaz trench and the subducted plate was sheared off. Recently the strike-slip zone migrated south from the Vitiaz trench across the northern Fiji Plateau and is presently extending from Aoba Island, in the New Hebrides, northeastward toward the Pacific Border Plateau.  相似文献