Flow‐field and palaeogeographic reconstruction of volcanic activity in the Permian Gerringong Volcanic Complex,southern Sydney Basin,Australia   总被引：1，自引：1，他引：0  

L. M. Campbell  P. J. Conaghan  R. H. Flood 《Australian Journal of Earth Sciences》2013,60(3):357-375

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Obituary     

D. Hill 《Australian Journal of Earth Sciences》2013,60(2):203-204

Geological sections are still best drawn at natural scale. Sections with vertical exaggerations are rarely drawn correctly, and even when computed carefully give a false notion of the structural features. Many schematic sections which are not drawn to scale and are supposed to explain a proposed new tectonic interpretation give such a distorted and frequently absurd picture of the structural features that they cannot be regarded as valid.  相似文献   

The petrology of the Mt Manypeaks Adamellite and associated high‐grade metamorphic rocks near Albany,Western Australia     

N. C. N. Stephenson 《Australian Journal of Earth Sciences》2013,60(4):413-439

The Mt Manypeaks Adamellite is a composite, regionally concordant pluton at least 22 km long and 3 km wide, associated with Precambrian amphibolite facies gneisses of the Albany‐Esperance Block, and situated about 35 km east of Albany, Western Australia. The pluton is surrounded by a granitised aureole, and shows structural and mineralogical harmony with the country rocks. Contacts vary from grada‐tional to sharp. Hence field relations are consistent with syn‐ or late‐kinematic emplacement in the catazone. The normative composition of the pluton corresponds with the thermal trough in the system An‐Ab‐Or‐Q‐H2O at 7 kb PH2O, suggesting an origin involving crystal‐melt equilibria. The pluton is believed to have formed almost in situ by partial anatexis of the country rocks at 700–750°C and a depth of about 25 km during the orogenic episode responsible for regional metamorphism and deformation.  相似文献   

Geochemisty and tectonic setting of igneous rocks in the Glenrock Station area,N.S.W.     

R. Offler 《Australian Journal of Earth Sciences》2013,60(3-4):443-455

In the Upper Murray Valley, Victoria, Late Silurian, high‐Si igneous rocks, which are closely associated with alkalic, basaltic dykes, were emplaced at high crustal levels following the peak of the Benambran Orogeny, which deformed and metamorphosed the Wagga Zone in Late Ordovician‐Early Silurian times. These rocks, which are informally termed ‘the Upper Murray high‐Si magmatic suite’, include leucogranites, rhyolite dykes and flows, and ash‐flow tuffs characterised by the following features. They are transitional from mildly peraluminous to mildly metaluminous; they represent relatively anhydrous magmas, in which halides were important volatile constituents; they have high Si, total alkalies, Rb, Th, U, Nb, Sn and heavy rare earth elements; and they are relatively repleted in Mg, Ca, Sr, Eu, V, Cr and Ni. In these respects and in their post‐orogenic setting and close association with alkalic basalts, they resemble many post‐orogenic granitoids from elsewhere. Such granitoids appear to have formed as partial melts during crustal extension following major episodes of deformation and high‐Si magmatism. A residual granulitic crust, from which an earlier generation of granitoid magmas had been extracted, is argued to be the source rock‐type for these post‐orogenic magmas. Tectonic extension, affecting such a crust, was accompanied by deep fracturing and basaltic vol‐canism. Mantle‐derived, CO₂‐ and halide‐rich fluids moved into the residual crust, causing widespread metasomatism, and emplacement of basaltic magma caused temperatures to rise until melting took place and a second group of magmas was produced. This model explains most aspects of the trace and major element chemistry of post‐orogenic, high‐Si igneous rocks and, for the Upper Murray high‐Si suite it also provides an explanation for variations in trace elements and isotopic characteristics. Other processes, such as crystal fractionation, magma mixing, thermogravi‐tational diffusion, and separation and loss of a volatile phase, provide explanations for variations within individual units of the suite, but they do not explain overall variations or the highly fractionated nature of the suite.  相似文献   

Facies architecture of the Early Devonian Ural Volcanics,New South Wales     

K. F. Bull  J. McPhie 《Australian Journal of Earth Sciences》2013,60(6):919-945

The Ural Volcanics are a early Devonian, submarine, felsic lava-sill complex, exposed in the western central Lachlan Orogen, New South Wales. The Ural Volcanics and underlying Upper Silurian, deepwater, basin-fill sedimentary rocks make up the Rast Group. The Ural Range study area, centrally located in the Cargelligo 1:100 000 map sheet area, was mapped at 1:10 000 scale. Seventeen principal volcanic facies were identified in the study area, dominated by felsic coherent facies (rhyolite and dacite) and associated monomictic breccia and siltstone-matrix monomictic breccia facies. Subordinate volcaniclastic facies include the pumice-rich breccia facies association, rhyolite – dacite – siltstone breccia facies and fiamme – siltstone breccia facies. The sedimentary facies association includes mixed-provenance and non-volcanic sandstone to conglomerate, black mudstone, micaceous quartz sandstone and foliated mudstone. The succession was derived from at least two intrabasinal volcanic centres. One, in the north, was largely effusive and intrusive, building a lava – sill complex. Another, in the south, was effusive, intrusive and explosive, generating lavas and moderate-volume (～3 km³) pyroclastic facies. The presence of turbidites, marine fossils, very thick massive to graded volcaniclastic units and black mudstone, and the lack of large-scale cross-beds and erosional scours, provide evidence for deposition in a submarine environment below storm wave-base. The Ural Volcanics have potential for seafloor or sub-seafloor replacement massive sulfide deposits, although no massive sulfide prospects or related altered zones have yet been defined. Sparse, disseminated sulfides occur in sericite-altered, steeply dipping shear zones.  相似文献   

An Optimised 1,10‐Phenanthroline Method for the Determination of Ferrous and Ferric Oxides in Silicate Rocks,Soils and Minerals     

Pranab K. Tarafder  Raghbendra Thakur 《Geostandards and Geoanalytical Research》2013,37(2):155-168

A precise, accurate and rapid method for the sequential determination of FeO and Fe₂O₃ in rocks, soils and some non‐refractory minerals by 1,10‐phenanthroline spectrophotometry is described. Fe(II) and Fe(III) were leached from the sample (?200 mesh) using a mixture of NH₄HF₂ and H₂SO₄ at 40–80 °C for 10 min on a hot plate. Both Fe(II) and Fe(III) could be conveniently estimated sequentially from the same reaction mixture at the μg g^?1 to percentage level. The method is better than the existing wet chemical methods, including the commonly used Pratt's titrimetric redox method, for Fe(II) and Fe(III) determinations in rock and soil samples in terms of precision, accuracy and rapidity. The throughput of the method was very high; at least forty to fifty samples could be estimated easily in a day. The results obtained compare favourably with those obtained by Pratt's method, as well as for certified/recommended values of a set of eleven certified reference materials having FeO and Fe₂O₃ contents in the range 0.21–14.63% and 0.58–8.48%, respectively. The optimised 1,10 phenanthroline method was found to be accurate to within 0.21% m/m FeO and 0.30% m/m Fe₂O₃ compared with the literature values of the certified reference materials studied.  相似文献   

内蒙古突泉盆地ZK-WJT钻井下侏罗统红旗组 生烃潜力   总被引：3，自引：1，他引：2  

蒋兴超  陈树旺  唐友军  张健  苏飞 《地质通报》2013,32(8):1236-1242

对突泉盆地西南缘ZK-WJT井红旗组烃源岩的发育特征和有机质丰度、类型及成熟度的研究表明,下侏罗统红旗组暗色泥岩发育,厚度达113.0m.有机碳的含量分布在0.56％～6.24％之间,平均值为1.90％.应用Pr/n-C17与Ph/n-C18的相关关系及C27、C28、C29甾烷(ααα-20R)三者的相对含量,判断其有机质类型为Ⅱ1型.镜质组反射率R.主要分布于1.26％～1.73％之间,平均值为1.37％;岩石热解参数Tmax主要为489.0～517.0℃,平均值为507.6℃,红旗组烃源岩属于成熟—高成熟演化阶段.综合评价认为,突泉盆地下侏罗统红旗组具备较好的生油气潜力.  相似文献   

An elastoplastic damage model for semi-brittle rocks     

《Geomechanics and Geoengineering》2013,8(4):253-267

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Reliability analysis of strength of cement treated soils     

《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(3-4):157-162

The design strength of cement treated soils and its variability are influenced by various contributing factors such as inherent variability of the soft ground as well as variations in the quantities of the additives used for improvement. To consider these variations, geotechnical designs use the factor of safety approach. This paper shows that the reliability-based analysis enables a rational choice of a design strength value for the cement-stabilised soft soil, considering the variations in the influencing input parameters in an appropriate manner. An approach for identifying the important variables governing the strength behaviour of improved soft soils is also illustrated.  相似文献   

Effect of shape on holding capacity of plate anchors buried in soft soil     

《Geomechanics and Geoengineering》2013,8(2):145-154

Plate anchor is one of the most common varieties of anchors used in the construction and maintenance work of various on-land and offshore structures. An accurate estimation of the uplift capacity of anchor foundations is necessary for an economical design as well as for the safety and stability of structures. This paper outlines the effect of shape of anchor plates on their breakout capacity, through a series of model tests. Both shallow and deep anchor behaviours were investigated under conditions developing suction force and without suction force. The results of these tests are presented in terms of load-displacement behaviour, variation of breakout factors (with and without suction force) with depth of embedment, the critical embedment depth of anchors and variation of suction force with embedment ratio. Further, the variations of breakout factor ratio with aspect ratio and embedment ratio are reported. Based on the experimental results and the model test results of other investigators an empirical relationship has been suggested to determine the shape factor and holding capacity of plate anchors buried in saturated cohesive soils.  相似文献