Putting the census on the web: lessons from two case studies

Summary This paper addresses the digital dissemination of geographically referenced census information in the UK. A number of important weaknesses in the 1991 model of data access are identified, and the possibility of future access to census information via the World Wide Web is then addressed in detail. Two case studies demonstrate the potential to overcome some fundamental weaknesses in earlier access models, including the provision of integrated data and metadata, graphical interfaces to geographical datasets, and an integrated interface and analysis environment.     

A powerful new model for the point source sky

I report further developments of the Wainscoatet al. (1992) (hereafter WCVWS) model of the point source sky. The newest version of this model now predicts cumulative or differential source counts, and integrated surface brightness of the sky due to smeared point sources, in any direction, for any infrared filter with passband within the range 2.0–35.0µm. The realistic representation of the Galaxy (disk, spiral arms and local spur, molecular ring, bulge, halo) and the extragalactic sky has been improved, guided by CO surveys of local molecular clouds. The newest version of the model is very well-validated by IRAS source counts; works well at B and V, even in the plane; and operates successfully in the far-ultraviolet (FUV). Applications discussed are: interpreting the new TMGS near-infrared survey of the plane; confusion in sky surveys; and seeking cosmological background radiation.     

Trace element signature and U–Pb geochronology of eclogite-facies zircon,Bergen Arcs,Caledonides of W Norway

Secondary-ion mass spectrometry (SIMS) U–Pb and trace element data are reported for zircon to address the controversial geochronology of eclogite-facies metamorphism in the Lindås nappe, Bergen Arcs, Caledonides of W Norway. Caledonian eclogite-facies overprint in the nappe was controlled by fracturing and introduction of fluid in the Proterozoic—Sveconorwegian—granulite-facies meta-anorthosite-norite protolith. Zircon grains in one massive eclogite display a core–rim structure. Sveconorwegian cores have trace element signatures identical with those of zircon in the granulite protolith, i.e. 0.31Th/U0.89, heavy rare earth element (HREE) enrichment, and negative Eu anomaly. Weakly-zoned to euhedral oscillatory-zoned Caledonian rims are characterized by Th/U0.13, low LREE content (minimum normalized abundance for Pr or Nd), variable enrichment in HREE, and no Eu anomaly. A decrease of REE towards the outermost rim, especially HREE, is documented. This signature reflects co-precipitation of zircon with garnet and clinozoisite in a feldspar-absent assemblage, and consequently links zircon to the eclogite-facies overprint. The rims provide a mean ²⁰⁶Pb/²³⁸U crystallization age of 423±4 Ma. This age reflects eclogite-forming reactions and fluid–rock interaction. This age indicates that eclogite-facies overprint in the Lindås nappe took place at the onset of the Scandian (Silurian) collision between Laurentia and Baltica.     

Nontronit und Pieotit aus dem Basalt des Ölberges bei Hundsangen,Westerwald

Zusammenfassung Der Basalt des Ölberges enthält an verschiedenen Stellen bis zu faustgroße, blasenförmige Einschlüsse von Nontronit. Der Nontronit zeigt eine starke Montmorillonit- und Saponitkomponente und hat folgende stöchiometrische Zusammensetzung: (Fe ₊₊₊ ^1,18 , Al_0,44, Cr_0,06, Mg_0,58, Fe ₊₊ ^0.01 )_2,27 [Al_0,22Si_3,75O₁₀] (OH)₂.Dem Nontronit ist ein Picotit (Mgo_0,58, Fe ₊₊ ^0,34 )_0.92 ( Al_1,36, Cr_0,64), beigemengt. Der Picotit hat die Gitterkonstante ₀= 8,18 Å und das spezifische Gewicht = 4,00 g/cm³. Die kleine Gitterkonstante und das geringe spezifische Gewicht des Picotits bestätigen, daß ein Mischkristall mit einer -Al₂O₃-Komponente vorliegt. Der Picotit weist außerdem einen Nickelgehalt von etwa 0,1% Ni0 in der Analyse auf.Neben Picotit sind in der Nontronitmasse einzelne Bronzitkriställchen vorhanden. Der Chromgehalt des Nontronits, der Chrom- und Nickelgehalt des Spinellminerals, sowie das Vorhandensein von Bronzit beweisen, daß der Nontronit im Basalt des Ölberges ein Zersetzungsprodukt von Olivinknollen ist.     

Direct measurement of the Si–O bond length and orientational disorder in the high-temperature phase of cristobalite

Neutron total scattering measurements from powdered samples of cristobalite have been used to determine the local structure in both the tetragonal and cubic phases. The results for the cubic phase show directly that the Si–O bonds are tilted at an angle of around 17° to the unit cell [111] direction. It is striking that the structure of β-cristobalite over the range 5–10 Å is closer to that of silica glass than α-cristobalite, which suggests that the local structure of β-cristobalite is not likely to consist of domains with the structure of α-cristobalite. The measurements show a small thermal expansion of the Si–O bonds over the temperature range 570–950 K.     

Ultramafic inclusions from San Carlos,Arizona: Petrologic and geochemical data bearing on their petrogenesis

Ultramafic inclusions from San Carlos, Arizona, are classified into two groups. Group I inclusions are dominated by magnesian (Mg/Mg + ΣFe= 0.86 – 0.91), olivine-rich peridotites containing Cr-rich clinopyroxene and spinel. The less abundant Group I pyroxenites (containing Mg- and Cr-rich pyroxenes) occur as discrete inclusions and as portions of composite inclusions where they have a sharp, planar interface with lherzolite. Group II inclusions are dominated by clinopyroxene-rich peridotites containing Al- and Ti-rich augite and commonly abundant, Al-rich spinel. Compared to Group I inclusions, they are more Fe-rich (Mg/Mg + ΣFe= 0.62 – 0.78) and more hetereogeneous in composition and modal proportions. Similar groups occur at many ultramafic inclusion localities.Our petrographic and geochemical results lead to the following conclusions. Olivine-rich Group I inclusions are not genetically related to the host basanite, and they are formed from two components. Component A is a partial melting residue; it comprises the major portion of these inclusions and determines the modal mineralogy and major and compatible trace element composition. Component B results from a small degree (<5%) of garnet peridotite melting (probably, within the low-velocity zone). This highly LIL-element-enriched melt has migrated upwards into the overlying component A where it crystallized primarily as clinopyroxene and amphibole, and thus, introduced LIL elements into the residual component A. Subsequent cooling and subsolidus recrystallization have removed textural evidence of this mixing. This model has also been proposed for olivine-rich Group I inclusions from Victoria, Australia. At Victoria and San Carlos some relatively clinopyroxene-rich Group I lherzolites are not contaminated by component B, and they represent the best estimates of upper mantle composition prior to melting. Group I orthopyroxenites may be fragments of tectonic layers formed in lherzolite, but they could also be early cumulates (now metamorphosed) from the melt in equilibrium with component A. Group I clinopyroxenites have geochemical features of clinopyroxene in equilibrium with a magma. Thus, they could also represent early cumulates (now metamorphosed) from a magma unrelated to the host basanite. Alternatively, their geochemical characteristics could result from more complex models such as residues from partial remelting of pyroxenite dikes and veins or intradike segregation processes such as filter pressing. All Group II inclusions studied appear to be cumulates derived from a SiO₂-undersaturated magma, possibly an early magma in the same volcanic episode which culminated with eruption of the host basanite. The poikilitic texture of amphibole-rich (kaersutite) inclusions is consistent with a cumulate origin. The bulk compositions of Group II inclusions are not equivalent to typical basaltic compositions.     

Australien C. Teichert,Stratigraphy of Western Australia

Ohne Zusammenfassung     

Largest dinosaur tracksite in China(Cretaceous,Zhaojue area,Sichuan Province): On the verge of destruction

The Zhaojue(ZJ) tracksites represent multiple steeply-inclined, track-bearing exposures in the clastic Feitianshan Formation of Sichuan Province that have been sequentially, excavated, mapped, expanded and destroyed, by quarrying,erosion or collapse, for almost three decades. The quarried area extends for more almost 1.0 km from north to south and ～0.5 km from east to west. Four important track-bearing surfaces have been identified and identified as ZJ-I, ZJ-II,ZJ-IIN and ZJ-III, some of which are newly exposed surfaces or expanded surfaces that were previously partially described. Others represent surfaces lost since they were first reported in papers published in 2014–2016. The ZJ-II site represents a hugely expanded continuation of a much smaller track-bearing surface described in 2014. It was mapped using drone technology, and now represents the largest tracksite in China, with a minimum count of 933 recognizable tracks, and the longest recorded sauropod and ornithopod trackways from China(～80 m and ～52 m respectively), which also reveal a pronounced change in the direction of trackmaker movement. The ZJ-II surface represents the best Zhaojue paleo-census sample giving a count of 68 individuals from 61 trackways(37 ornithopod, 10 theropod, 14 sauropod) and isolated tracks(representing 7 individuals). Thus, ornithopods(both large and small trackmakers) represent ～54% of the total number of trackways. The smaller ZJ-III surface was mapped using traditional methods, and reveals at least 6 ornithopod-and 4 theropod trackways. Both the ZJ-II and ZJ-III surfaces reveal parallel ornithopod trackways suggestive of social or gregarious behavior. The combined data from all four Zhaojue surfaces reveal a total of 1928 tracks, and include a few previously reported pterosaurs and theropod swim tracks. The Zhaojue quarry complex provide a good example of multiple track-bearing sites(surfaces) that require long term study and monitoring to extract as much trackway data as possible before in situ physical evidence is lost.