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Abstract. The secondary production of Spisula subtruncata (somatic production) is calculated in the framework of a benthic monitoring study in a coastal area. The temporal trends of density, biomass and growth increments are examined in the three year-classes present. These are compared to certain physical and chemical parameters. 相似文献
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Prospectivity analyses are used to reduce the exploration search space for locating areas prospective for mineral deposits.The scale of a study and the type of mineral system associated with the deposit control the evidence layers used as proxies that represent critical ore genesis processes.In particular,knowledge-driven approaches(fuzzy logic)use a conceptual mineral systems model from which data proxies represent the critical components.These typically vary based on the scale of study and the type of mineral system being predicted.Prospectivity analyses utilising interpreted data to represent proxies for a mineral system model inherit the subjectivity of the interpretations and the uncertainties of the evidence layers used in the model.In the case study presented,the prospectivity for remobilised nickel sulphide(NiS)in the west Kimberley,Western Australia,is assessed with two novel techniques that objectively grade interpretations and accommodate alternative mineralisation scenarios.Exploration targets are then identified and supplied with a robustness assessment that reflects the variability of prospectivity value for each location when all models are considered.The first technique grades the strength of structural interpretations on an individual line-segment basis.Gradings are obtained from an objective measure of feature evidence,which is the quantification of specific patterns in geophysical data that are considered to reveal underlying structure.Individual structures are weighted in the prospectivity model with grading values correlated to their feature evidence.This technique allows interpreted features to contribute prospectivity proportional to their strength in feature evidence and indicates the level of associated stochastic uncertainty.The second technique aims to embrace the systemic uncertainty of modelling complex mineral systems.In this approach,multiple prospectivity maps are each generated with different combinations of confidence values applied to evidence layers to represent the diversity of processes potentially leading to ore deposition.With a suite of prospectivity maps,the most robust exploration targets are the locations with the highest prospectivity values showing the smallest range amongst the model suite.This new technique offers an approach that reveals to the modeller a range of alternative mineralisation scenarios while employing a sensible mineral systems model,robust modelling of prospectivity and significantly reducing the exploration search space for Ni. 相似文献
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The role of life‐history traits,selective pressure and hydrographic boundaries in shaping the genetic structure of the transparent goby,Aphia minuta 
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The Palaeoproterozoic Yerrida, Bryah and Padbury Basins record periods of sedimentation and magmatism along the northern margin of the Archaean Yilgarn Craton. Each basin is characterised by distinct stratigraphy, igneous activity, structural and metamorphic history and mineral deposit types. The oldest of these basins, the Yerrida Basin (ca 2200 Ma) is floored by rocks of the Archaean Yilgarn Craton. Important features of this basin are the presence of evaporites and continental flood basalts. The ca 2000 Ma Bryah Basin developed on the northern margin of the Yilgarn Craton during backarc sea‐floor spreading and rifting, the result of which was the emplacement of voluminous mafic and ultramafic volcanic rocks. During the waning stages of the Bryah Basin this mafic to ultramafic volcanism gave way to deposition of clastic and chemical sedimentary rocks. At a later stage, the Padbury Basin developed as a retroarc foreland basin on top of the Bryah Basin in a fold‐and‐thrust belt. This resulted from either the collision of the Pilbara and Yilgarn Cratons (Capricorn Orogeny) or the ca 2000 Ma westward collision of the southern part of the Gascoyne Complex and the Yilgarn Craton (Glenburgh Orogeny). During the Capricorn Orogeny the Bryah Group was thrust to the southeast, over the Yerrida Group. Important mineral deposits are contained in the Yerrida, Bryah and Padbury Basins. In the Yerrida Basin a large Pb–carbonate deposit (Magellan) and black shale‐hosted gossans containing anomalous abundances of Ba, Cu, Zn and Pd are present. The Pb–carbonate deposit is hosted by the upper units of the Juderina Formation, and the lower unit of the unconformably overlying Earaheedy Group. The Bryah and Padbury Basins contain orogenic gold, copper‐gold volcanogenic massive sulfides, manganese and iron ore. The origin of the gold mineralisation is probably related to tectonothermal activity during the Capricorn Orogeny at ca 1800 Ma. 相似文献
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Occhipinti Giuseppe Cali&#; Ivo D&#;Altri Antonio Maria Grillanda Nicola de Miranda Stefano Milani Gabriele Spacone Enrico 《Bulletin of Earthquake Engineering》2022,20(4):2219-2244
Bulletin of Earthquake Engineering - This paper reports the results of different finite and discrete element simulations on a well-known benchmark of an unreinforced plane masonry structure.... 相似文献
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Castellazzi G. Pant&#; B. Occhipinti G. Talledo D. A. Berto L. Camata G. 《Bulletin of Earthquake Engineering》2022,20(4):2159-2185
Bulletin of Earthquake Engineering - The paper presents the comparison of the results obtained on a masonry building by nonlinear static analysis using different software operating in the field of... 相似文献
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A.R.A.Aitken S.A.Occhipinti M.D.Lindsay A.Joly H.M.Howard S.P.Johnson J.A.Hollis C.V.Spaggiari I.M.Tyler T.C.McCuaig M.C.Dentith 《地学前缘(英文版)》2018,9(2):295-316
The cratonisation of Western Australia during the Proterozoic overlapped with several key events in the evolution of Earth. These include global oxidation events and glaciations, as well as the assembly,accretionary growth, and breakup of the supercontinents Columbia and Rodinia, culminating in the assembly of Gondwana. Globally, Proterozoic mineral systems evolved in response to the coupled evolution of the atmosphere, hydrosphere, biosphere and lithosphere. Consequently, mineral deposits form preferentially in certain times, but they also require a favourable tectonic setting. For Western Australia a distinct plate-margin mineralisation trend is associated with Columbia, whereas an intraplate mineralisation trend is associated with Rodinia and Gondwana, each with associated deposit types. We compare the current Proterozoic record of ore deposits in Western Australia to the estimated likelihood of oredeposit formation. Overall likelihood is estimated with a simple matrix-based approach that considers two components: The "global secular likelihood" and the "tectonic setting likelihood". This comparative study shows that at least for the studied ore-deposit types, deposits within Western Australia developed at times, and in tectonic settings compatible with global databases. Nevertheless, several deposit types are either absent or poorly-represented relative to the overall likelihood models. Insufficient exploration may partly explain this, but a genuine lack of deposits is also suggested for some deposit types. This may relate either to systemic inadequacies that inhibited ore-deposit formation, or to poor preservation. The systematic understanding on the record of Western Australia helps to understand mineralisation processes within Western Australia and its past connections in Columbia, Rodinia and Gondwana and aids to identify regions of high exploration potential. 相似文献
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The Palaeoproterozoic Bryah, Padbury and Yerrida Basins are situated along the northwestern margin of the Archaean Yilgarn Craton, central Western Australia. These basins form part of the Capricorn Orogen, which developed between 2.0 and 1.8 Ga as a result of the collision between the Archaean Pilbara and Yilgarn cratons. The Bryah, Padbury and Yerrida Basins, which at the present day cover a total area of ca 20 000 km2, were formerly considered as one geological entity, the Glengarry Basin. These three basins are characterized by distinct stratigraphy, igneous activity, structural and metamorphic history, and mineral deposit types. Igneous activity only affected the Bryah and Yerrida Basins, with voluminous eruptions of tholeiitic magma. In the Bryah Basin tholeiitic volcanic rocks are Mg-rich and have mixed MORB to oceanic island chemical signatures, but with a boninitic (subduction-related) component. In the Yerrida Basin tholeiites are Fe-rich and have chemical signatures that suggest a mixed tectonic environment ranging from oceanic to continental. It is considered possible that this tholeiitic magmatism is related to a mantle plume. Two models for the tectonic evolution of the Bryah, Padbury and Yerrida Basins are proposed: (1) the Bryah and Yerrida Basins were formed in a back-arc setting, whilst the Padbury Basin developed as a retro-arc foreland basin over the Bryah Basin; and/or (2) strike-slip transtension, during and following the Pilbara-Yilgarn collision, created the Bryah and Yerrida strike-slip pull-apart Basins. A change in regional stress regime resulted in the inversion of the basins and the development of a foreland basin in the northwest (Padbury Basin). 相似文献