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Abstract: Landslide research at the British Geological Survey (BGS) is carried out through a number of activities, including surveying, database development and real-time monitoring of landslides. Landslide mapping across the UK has been carried out since BGS started geological mapping in 1835. Today, BGS geologists use a combination of remote sensing and ground-based investigations to survey landslides. The development of waterproof tablet computers (BGS·SIGMAmobile), with inbuilt GPS and GIS for field data capture provides an accurate and rapid mapping methodology for field surveys. Regional and national mapping of landslides is carried out in conjunction with site-specific monitoring, using terrestrial LiDAR and differential GPS technologies, which BGS has successfully developed for this application. In addition to surface monitoring, BGS is currently developing geophysical ground-imaging systems for landslide monitoring, which provide real-time information on subsurface changes prior to failure events. BGS’s mapping and monitoring activities directly feed into the BGS National Landslide Database, the most extensive source of information on landslides in Great Britain. It currently holds over 14?000 records of landslide events. By combining BGS’s corporate datasets with expert knowledge, BGS has developed a landslide hazard assessment tool, GeoSure, which provides information on the relative landslide hazard susceptibility at national scale. 相似文献
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Andrea L. FOSTER 《《地质学报》英文版》2017,91(Z1):12-12
In its cationic,trivalent form,Chromium(Cr)it is a micronutrient,and exhibits low environmental mobility.In hexavalent form,however,it is a human carcinogen and also highly mobile.Climate is a key environmental factor controlling weathering rates and stability of primary and secondary Cr-bearing minerals.Knowledge of Cr oxidation state and mineral residence is therefore essential to estimating the risk posed by Cr in serpentinites,chromite mine wastes,and soils developed on these parent materials.X-ray absorption spectroscopy(XAS)is currently the best available technique for determination of the relative abundance of Cr(III)and Cr(VI)in situ(that is,without digestion of solid phases).A brief review of relevant XAS studies of is presented below,focusing on studies in tropical climates1,as they will be most relevant to eastern Cuba’s extensively serpentinized ophiolite belt.Cr(III)-bearing spinels are usually the dominant and most refractory Cr host in ultramafic rocks.Previous XAS studies2 indicate that in tropical climates,Cr-spinels weather rapidly to form Cr(III)-bearing secondary Fe(III)(hydr)oxides(goethite,hematite).Manganese(Mn)is also enriched in ultramafic rocks2;as Mn(IV),it can also co-precipitate with Fe(III)(hydr)oxides,or form its own secondary(hydr)oxides.A previous study found up to 20%Cr(VI)in in a tropical,serpentine soil that contained substantial Mn,and a strong correlation between the*amounts of Cr(VI)and Mn(IV)in the soil profile2.Theresults of several XAS studies suggest that a close association of Mn(IV)and Cr(III)in secondary Fe(hydr)oxides is necessary for oxidation of Cr(III)to Cr(VI)via electron transfer reactions with Mn(IV);however,additional XAS studies have shown that organic matter3and Cr-bearing aluminosilicates4 may also be important sources of Cr(III)to the environment under specific conditions.The stability and fate of Cr has not been studied in detail for these two host phase types,to the best of our knowledge.Access to XAS facilities to perform Cr geochemical experiments is limited and will only become more so in the future.We are working to develop and apply(micro)Raman spectroscopy to evaluate Cr oxidation state and mineral residence(in crystalline and amorphous materials).In addition to standard Raman scattering,we are employing resonance Raman(785 nm laser)to enhance signal from Cr(VI)-bearing phases and laser-stimulated photoluminescence to identify Cr(III)associated with Al-rich alteration products 相似文献
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MODELING EPHEMERAL GULLY EROSION FOR CONSERVATION PLANNING 总被引：9，自引：0，他引：9
George R. FOSTER 《国际泥沙研究》2005,20(3):157-175
1INTRODUCTIONEphemeral gully erosion,which is caused by concentrated flow within cultivated farm fields,is distinct from rill erosion.Ephemeral gully erosion is also distinct from gully erosion in permanent,deep,incised channels,formed by headcuts moving upstream.Ephemeral gully erosion is often overlooked.It is not estimated with rill-interrill erosion prediction technology such as the Revised Universal Soil Loss Equation(Renard et al.,1997),and it is often not measured in field survey… 相似文献
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Anton T. KEARSLEY Mark J. BURCHELL Mark C. PRICE Michael J. COLE Penelope J. WOZNIAKIEWICZ Hope A. ISHII John P. BRADLEY Marc FRIES Nicholas J. FOSTER 《Meteoritics & planetary science》2012,47(4):737-762
Abstract– The Stardust collector shows diverse aerogel track shapes created by impacts of cometary dust. Tracks have been classified into three broad types (A, B, and C), based on relative dimensions of the elongate “stylus” (in Type A “carrots”) and broad “bulb” regions (Types B and C), with occurrence of smaller “styli” in Type B. From our experiments, using a diverse suite of projectile particles shot under Stardust cometary encounter conditions onto similar aerogel targets, we describe differences in impactor behavior and aerogel response resulting in the observed range of Stardust track shapes. We compare tracks made by mineral grains, natural and artificial aggregates of differing subgrain sizes, and diverse organic materials. Impacts of glasses and robust mineral grains generate elongate, narrow Type A tracks (as expected), but with differing levels of abrasion and lateral branch creation. Aggregate particles, both natural and artificial, of a wide range of compositions and volatile contents produce diverse Type B or C shapes. Creation of bulbous tracks is dependent upon impactor internal structure, grain size distribution, and strength, rather than overall grain density or content of volatile components. Nevertheless, pure organic particles do create Type C, or squat Type A* tracks, with length to width ratios dependent upon both specific organic composition and impactor grain size. From comparison with the published shape data for Stardust aerogel tracks, we conclude that the abundant larger Type B tracks on the Stardust collector represent impacts by particles similar to our carbonaceous chondrite meteorite powders. 相似文献
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A new method for suppressing multiple reflections in seismograms is developed. It is based on a downward continuation procedure which uses the full acoustic wave equation (hyperbolic form) as a downward continuation operator. We demonstrate that the downward continuation of the recorded wave field maps a reflectivity function without multiply reflected events. The method is applied successfully to individual traces of plane-wave decomposed (slant-stacked) synthetic and field data. 相似文献
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Abstract The main porphyroblastic minerals in schists and phyllites of the Foothills terrane, Western Metamorphic Belt, central Sierra Nevada, California, are cordierite and andalusite (mostly chiastolite). Less commonly, biotite, muscovite, chlorite, garnet or staurolite are also present as porphyroblasts. The variety of porphyroblast and matrix microstructures in these rocks makes them suitable for testing three modern hypotheses on growth and deformation of porphyroblasts: (1) porphyroblast growth is always syndeformational; (2) porphyroblasts nucleate only in low-strain, largely coaxially deformed, quartz-rich (Q) domains of a crenulation foliation and are dissolved in active high-strain, non-coaxially deformed, mica-rich (M) domains, the spacing between which limits the size of the porphyroblasts; and (3) porphyroblasts generally do not rotate, with respect to geographical coordinates, during deformation, provided they do not deform internally, so that they may be used as reliable indicators of the orientation of former regional structural surfaces, even on the scale of orogenic belts. Some porphyroblast–matrix relationships in the Foothills terrane are inconsistent with hypotheses 1 and 2, and others are equivocal. For example, in many rocks it cannot be determined whether the porphyroblasts grew where the strain had already been partitioned into M and Q domains, whether the porphyroblasts caused this partitioning, or both. Although most porphyroblasts appear to be syndeformational, as predicted by hypothesis 1, observations that do not support the general application of hypotheses 1 and 2 to rocks of the Foothills terrane include: (a) lack of residual crenulations in many strain-shadows and alternative explanations where they are present; (b) absence of porphyroblasts smaller than the distance between nearest mica-rich domains; (c) nucleation of crenulations on existing porphyroblasts, rather than nucleation of porphyroblasts between existing crenulations; (d) presence of micaceous ‘arcs’in an undifferentiated matrix against some porphyroblasts, suggesting static growth; (e) absence of crenulations in porphyroblastic rocks showing sedimentary bedding; and (f) porphyroblasts with very small, random inclusions, which are probably pre-deformational. Similarly, porphyroblasts that have overgrown sets of crenulations and porphyroblasts with micaceous ‘arcs’are probably post-deformational, at least on the scale of a large thin section and probably over much larger areas, judging from mesoscopic structural evidence. Some porphyroblasts in rocks of the Foothills terrane do not appear to have rotated, with respect to geographical coordinates, during matrix deformation, in accordance with hypothesis 3, at least on the scale of a large thin section. However, other porphyroblasts evidently have rotated. In some instances, this appears to be due to mutual interference, but many apparently rotational porphyroblasts are too far apart to have interfered with each other, which indicates that the rotation was associated with deformation of the matrix. The occurrence of planar bedding surfaces adjacent to porphyroblasts about which bedding and/or foliation surfaces are folded suggests rotation of the porphyroblasts during non-coaxial flow parallel to bedding, rather than crenulation of the matrix foliation around static porphyroblasts. It appears that porphyroblasts may rotate during deformation if the matrix is relatively homogeneous, so that the strain is effectively non-coaxial. This may occur after homogenization of a matrix in response to the strongest degree of crenulation folding, whereas the same porphyroblasts may have been inhibited from rotating previously, when strain accumulation was partitioned in the matrix. 相似文献
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John C. BRIDGES Mark J. BURCHELL Hitesh C. CHANGELA Nick J. FOSTER J. Alan CREIGHTON James D. CARPENTER Steve J. GURMAN Ian A. FRANCHI Henner BUSEMANN 《Meteoritics & planetary science》2010,45(1):55-72
Abstract– We have used synchrotron Fe‐XANES, XRS, microRaman, and SEM‐TEM analyses of Stardust track 41 slice and track 121 terminal area slices to identify Fe oxide (magnetite‐hematite and amorphous oxide), Fe‐Ti oxide, and V‐rich chromite (Fe‐Cr‐V‐Ti‐Mn oxide) grains ranging in size from 200 nm to ～10 μm. They co‐exist with relict FeNi metal. Both Fe‐XANES and microRaman analyses suggest that the FeNi metal and magnetite (Fe2O3FeO) also contain some hematite (Fe2O3). The FeNi has been partially oxidized (probably during capture), but on the basis of our experimental work with a light‐gas gun and microRaman analyses, we believe that some of the magnetite‐hematite mixtures may have originated on Wild 2. The terminal samples from track 121 also contain traces of sulfide and Mg‐rich silicate minerals. Our results show an unequilibrated mixture of reduced and oxidized Fe‐bearing minerals in the Wild 2 samples in an analogous way to mineral assemblages seen in carbonaceous chondrites and interplanetary dust particles. The samples contain some evidence for terrestrial contamination, for example, occasional Zn‐bearing grains and amorphous Fe oxide in track 121 for which evidence of a cometary origin is lacking. 相似文献
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ALLEN C. M.; WOODEN J. L.; HOWARD K. A.; FOSTER D. A.; TOSDAL R. M. 《Journal of Petrology》1995,36(6):1675-1700
Ages and initial isotopic ratios of Early Cretaceous ({smalltilde}100 Ma) plutons of the Cordilleran Interior in the southernTurtle and West Riverside mountains distinguish them from LateCretaceous plutons in surrounding ranges in the eastern MojaveDesert. Furthermore, the studied plutons have isotopic and geochemicalcharacteristics more similar to plutons of Cretaceous age inthe coastal batholiths (Peninsular Ranges and Sierra Nevada)than to most Mesozoic plutons in the Cordilleran Interior. Thestudied plutons are calcic, in contrast to the mostly cak-alkalineMesozoic plutons of the eastern Mojave Desert. Distinctive isotopicsignatures of the granitoids include lower initial 87Sr/86Srof 0•705–0•710, 18O of +6•3 to +7•7,208Pb/204Pb of 38•3–39•5, and higher Nd of –3•86to –9•60 than the Late Cretaceous plutons in theregion. The distinctive characteristics of these Early Cretaceousplutons are probably both location and time specific and resultfrom: (1) emplacement in a cold, untapped ‘Mojave-type’Proterozoic upper crust, (2) a significant component of basalticmagmas partially melted from the asthenosphere or subcontinentallithosphere and (3) a magmatic component derived from Proterozoic,mafic, lower crust. They interacted less with their crustalhosts than did the later, more voluminous Late Cretaceous plutons. KEY WORDS: Cordilleran Interior; Cretaceous; Mojave; pscudothron; Turtle Mountains 相似文献
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The First Stegosaur （Dinosauria, Ornithischia） from the Upper Jurassic Shishugou Formation of Xinjiang, China 总被引：1，自引：0，他引：1 
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下载免费PDF全文 JIA Chengkai Catherine A. FOSTER XU Xing James M. CLARK 《《地质学报》英文版》2007,81(3):351-356
A new stegosaur species, Jiangjunosaurus junggarensis, gen. et sp. nov., is erected based on a specimen collected from the Upper Jurassic upper section of the Shishugou Formation in the Junggar Basin, Xinjiang, China. It represents the first stegosaur from the Jurassic of Xinjiang and increases the diversity of the dinosaur fauna in the Shishugou Formation. The new genus is characterized by symmetrical and proportionally wide tooth crowns, a sub-rectangular axial neural spine seen in lateral view, and large openings on the lateral surfaces of the cervical centra. A preliminary character analysis suggests that this new taxon is more derived than the Middle Jurassic stegosaur Huayangosaurus but more primitive than most other known stegosaur species. 相似文献