Determination of High Field Strength Elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g−1 Levels in Geological Reference Materials by Magnetic Sector ICP-MS after HF/HClO4 High Pressure Digestion

Six low abundance rock reference materials (basalt BIR-1, dunite DTS-1, dolerite DNC-1, peridotite PCC-1, serpentine UB-N and basalt TAFAHI) have been analysed for high field strength elements (Zr, Nb, Hf, Ta, Th and U), Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g⁻¹ levels (in rock) by magnetic sector inductively coupled plasma-mass spectrometry after HF/HClO₄ high pressure decomposition. The adopted method uses only indium as an internal standard. Detection limits were found to be in the range of 0.08 to 16.2 pg ml⁻¹ in solution (equivalent to 0.08 to 16.2 ng g⁻¹ in rock). Our data for high field strength elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi for the six selected low abundance geological reference materials show general agreement with previously published data. Our Ta values in DTS-1 and PCC-1 (1.3 and 0.5 ng g⁻¹) are lower than in previously published studies, providing smooth primitive mantle distribution patterns. Lower values were also found for Tl in BIR-1, DTS-1 and PCC-1 (2, 0.4 and 0.8 ng g⁻¹). Compared with quadrupole ICP-MS studies, the proposed magnetic sector ICP-MS method can generally provide better detection limits, so that the measurement of high field strength elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g⁻¹ levels can be achieved without pre-concentration, ion exchange separation or other specialised techniques.     

Evidence for centennial-scale Lateglacial and early Holocene climatic complexity from Quoyloo Meadow,Orkney, Scotland

The influence of the North Atlantic on the margins of Europe means the region is particularly sensitive to changes in the ocean–atmospheric system. During the Last Glacial–Interglacial Transition (16–8 cal ka bp ) this system was repeatedly disrupted, leading to a series of abrupt and short-lived shifts in climate. Despite much research, the number and magnitude of these ‘centennial-scale’ events is not well understood. To address this, we expand upon investigations at Quoyloo Meadow, Orkney, Scotland, one of the best chronologically constrained palaeoclimate records in northern Britain. By coupling stable isotope and chironomid fossil analyses with existing data, this study identifies multiple phases of centennial-scale disturbance at: c. 14.0, 11.1, 10.8, 10.5, 10.45 and 10.3 cal ka bp , with the events at 14.0 and 10.3 exhibiting a particularly pronounced cold-climate signature. During the Holocene, the strongest response to climate forcing was at c. 10.3–10.0 cal ka bp , expressed as a two-stage drop in mean July temperatures, a shift in pollen spectra indicative of ‘less-stable’ climatic regimes, and a depletion in δ¹⁸O values. We interpret this as the first reliably dated incidence of the ‘10.3-ka event’ in the British Isles and consider the wider impact of this climatic reversal in other Holocene records.     

The legacy of crystal-plastic deformation in olivine: high-diffusivity pathways during serpentinization

Crystal-plastic olivine deformation to produce subgrain boundaries composed of edge dislocations is an inevitable consequence of asthenospheric mantle flow. Although crystal-plastic deformation and serpentinization are spatio-temporally decoupled, we identified compositional readjustments expressed on the micrometric level as a striped Fe-enriched ( [`(X)]<sub>\textFe</sub> \bar{X}_{\text{Fe}}  = 0.24 ± 0.02 (zones); 0.12 ± 0.02 (bulk)) or Fe-depleted ( [`(X)]_\textFe \bar{X}_{\text{Fe}}  = 0.10 ± 0.01 (zones); 0.13 ± 0.01 (bulk)) zoning in partly serpentinized olivine grains from two upper mantle sections in Norway. Focused ion beam sample preparation combined with transmission electron microscopy (TEM) and aberration-corrected scanning TEM, enabling atomic-level resolved electron energy-loss spectroscopic line profiling, reveals that every zone is immediately associated with a subgrain boundary. We infer that the zonings are a result of the environmental Fe²⁺Mg₋₁ exchange potential during antigorite serpentinization of olivine and the drive toward element exchange equilibrium. This is facilitated by enhanced solid-state diffusion along subgrain boundaries in a system, which otherwise re-equilibrates via dissolution-reprecipitation. Fe enrichment or depletion is controlled by the silica activity imposed on the system by the local olivine/orthopyroxene mass ratio, temperature and the effect of magnetite stability. The Fe-Mg exchange coefficients K_\textD^{\textAtg/\textOl} K_{\text{D}}^{{{\text{Atg}}/{\text{Ol}}}} between both types of zoning and antigorite display coalescence toward exchange equilibrium. With both types of zoning, Mn is enriched and Ni depleted compared with the unaffected bulk composition. Nanometer-sized, heterogeneously distributed antigorite precipitates along olivine subgrain boundaries suggest that water was able to ingress along them. Crystallographic orientation relationships gained via electron backscatter diffraction between olivine grain domains and different serpentine vein generations support the hypothesis that serpentinization was initiated along olivine subgrain boundaries.     

Conservation and community in the new South Africa: A case study of the Mahushe Shongwe Game Reserve

The idealization of natural landscapes and peoples during colonialism, coupled with the popularity of sustainable development in the postcolonial era, has contributed to the expansion of conservation planning throughout the African continent. Concerns surrounding the promotion of national and international conservation agendas at the expense of local livelihood needs have generated interest in community conservation projects that attempt to include local participation and knowledge in natural resource management. The early excitement associated with community conservation has waned in light of recent assessments that it has been unsuccessful in meeting its ecological and social goals. This parallels other research that suggests communities are understood in generic or homogenous ways that influence how these initiatives are understood. Using a case study of the Mahushe Shongwe Game Reserve, this paper evaluates how rural households access environmental and economic resources to produce livelihoods, and how these access patterns impact their views of the project. It is argued that there are significant livelihood variations within the community that shape the ways households engage with, and benefit from, conservation planning. Rather than strictly viewing Mahushe Shongwe as a constraint to environmental resource access or site for limited employment, community members identify a number of benefits from its existence including education and development opportunities. Additionally, transformations in governance systems in the region impact community views of the project since younger residents are less likely to engage with the Matsamo Tribal Authority, which participates in managing the reserve. The consequence is that conservation has various impacts and meanings within a specific community that remain tied to the livelihood and governance systems being renegotiated in the post-apartheid era.     

欧洲莱茵河流域洪水管理行动计划述评

旨在提高和改善莱茵河的防洪和流域可持续管理水平的“洪水管理行动计划”于1998年开始实施,其内容和措施以及欧洲国家在流域可持续发展管理方面的思路和模式对我国江河流域的防洪和洪泛区管理可资借鉴.     

Europium-activated cathodoluminescence in minerals

Cathodoluminescence observations give information on the presence of europium in several minerals including apatite, fluorite, strontianite, and scheelite. Information on the oxidation state of the crystallization environment and on the partitioning of europium between coexisting mineral pairs may be obtained.The apatite in carbonatites and genetically related igneous rocks almost always contains europium in the divalent state. Occasionally both divalent and trivalent europium are observed.Europium is preferentially incorporated into strontianite when it crystallizes together with apatite in these same rocks. Similar results are found for fiuorite.     

Iron-formations and epigenetic ironstones in the Palaeoproterozoic Willyama Supergroup, Olary Domain, South Australia

Summary Iron-formations occur as massive to compositionally layered, Fe oxide-rich, concordant bodies in the Palaeoproterozoic Willyama Supergroup of the Olary Domain, South Australia. They have constitutional similarities to those occurring in the neighbouring Broken Hill Domain. The most abundant iron-formations are in the Quartzofeldspathic Suite and comprise magnetite-quartz assemblages (± hematite, barite, actinolite, apatite). Hematite, magnetite, albite, quartz, Ca(Na) amphibole(s), CaNaFe clinopyroxene and andraditic garnet are major constituents of rare calc-silicate iron-formations in the Bimba and Calcsilicate Suites, whereas magnetite, quartz, almandine-spessartine, manganoan fayalite, manganoan grunerite and apatite form manganiferous iron-formations in the Pelite Suite. The pronounced differences in mineralogy of the three iron-formation types are the result of regional metamorphism of diverse hydrothermal precipitates with variable elastic components, together with the local effects of high-temperature metasomatic alteration. Metasomatic fluids were produced as a result of devolatilisation of the evaporite-bearing volcanosedimentary sequence, during and following amphibolite grade metamorphism and deformation, which led to localised and regional-scale hydrothermal alteration. In places, there was extensive metasomatic reconstitution (veining, brecciation, replacement) of iron-formations and associated rocks, caused by high-temperature (350°–650°C), oxidising, saline fluids. The resulting epigenetic ironstones are dominated by magnetite-hematite-quartz with minor sulfides and display enrichment in Fe, Ti, Cu, Au, Sc, U, V, Y, Zn and HREE relative to parental iron-formations.

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Eisenformationen und epigenetische Eisensteine in der Paläoproterozoischen Willyama Supergroup, Olary Domäne, Südaustralien

Zusammenfassung Eisenformationen kommen als massige bis in der Zusammensetzung geschichtete, Eisenoxidreiche, konkordante Körper in der paläoproterozoischen Willyama Supergroup der Olary Domäne, Südaustralien, vor. Sie haben konstitutionelle Ähnlichkeiten mit Vorkommen in der benachbarten Broken Hill Domäne. Die häufigsten Eisenformationen befinden sich in der Quartzofeldspathic Suite and bestehen aus Magnetit und Quarz (± Hämatit, Baryt, Aktinolit, Apatit). Hämatit, Magnetit, Albit, Quarz, Ca(Na) Amphibol(e), CaNaFe Klinopyroxen und andraditischer Granat sind Hauptbestandteile von seltenen Kalksilikat-Eisenformationen in den Bimba und Calcsilicate Suites, während Magnetit, Quartz, Almandin-Spessartin, manganhaltiger Fayalit, manganhaltiger Grunerit und Apatit manganhaltige Eisenformationen in der Pelite Suite bilden. Die ausgeprägten Unterschiede in der Mineralogie der drei Typen von Eisenformationen sind durch Regionalmetamorphose von diversen hydrothermalen Ausfällungen mit variablen klastischen Komponenten verursacht worden, zusammen mit lokalen Wirkungen einer hock-Temperatur metasomatischen Alteration. Metasomatische Fluide wurden während und nach der Amphibolitmetamorphose und Deformation durch Devolatilisation der evaporithaltigen vulkanosedimentären Abfolge produziert, die sowohl zu lokaler, wie auch zu weiträumiger hydrothermaler Alteration führten. Örtlich kam es zu umfangreicher metasomatischer Rekonstitution (Gangbildung, Brekkzierung, Verdrängung) von Eisenformationen und assoziierten Gesteinen verursacht durch hoch-Temperatur (350°–650°C), oxidierte, saline Fluide. Die resultierenden epigenetischen Eisensteine bestehen hauptsächlich aus Magnetit, Hämatit, und Quarz mit Sulfiden und weisen eine Anreicherung in Fe, Ti, Cu, Au, Sc, U, V, Y, Zu und SREE relativ gegenüber den ursprünglichen Eisenformationen auf.

     

Deformation and mineralisation in the Scotty Creek Basin,Agnew district,Eastern Goldfields,Western Australia: evidence for D1- and D3-related gold mineralisation

Gold deposits in the Agnew district display markedly different structural styles. The Waroonga and Songvang deposits are hosted in layer-parallel extensional shears formed under highly ductile conditions. In contrast, the New Holland–Genesis deposits are shallow-dipping quartz-filled brittle fractures and breccia zones that cut across the tightly folded bedding and formed during east–west compression. It is difficult to attribute their formation to a single compressive event. The Waroonga and Songvang deposits formed during D₁ extension, uplift and exhumation of the Agnew granitic complex and formation of the Scotty Creek Basin at ca 2670–2660?Ma. The New Holland–Genesis deposits formed during east–west D₃ compression at about ca 2650–2630?Ma. An S₁ foliation wraps around the Agnew granitic complex and L₁ stretching lineations form a radial pattern around the granite, consistent with formation during D₁ uplift of the composite granite body. Uplift and erosion of granite bodies in the surrounding area provide a source for the granite clasts in the upper parts of the Scotty Creek Basin. As clasts in the basin are undeformed, no significant deformation occurred prior to the uplift and erosion of the source granites in this area. Syn-tectonic emplacement of the Lawlers Tonalite during formation of the Scotty Creek Basin at ca 2665?Ma may have provided a good heat/fluid source for the mineralising systems during the first gold event. The distribution of the large deposits along the western edge of the Agnew granitic complex indicates that the extensional shear along the granite contact is a first-order control on gold deposition by providing a conduit for rising hydrothermal fluids. The northerly trend of high-grade shoots in the Waroonga deposit coincides with early north-trending growth faults, which are also likely fluid conduits.