Classifying mineral potential in support of land-use policy decisions in British Columbia,Canada     

Graeme P. McLaren 《Natural Resources Research》1992,1(1):85-96

British Columbia covers a vast segment of the Cordillera Mountain system that is richly endowed with a diversity of resources. British Columbia's historic patterns of resource development increasingly have been in conflict with demands for greater environmental protection. To avoid such conflicts, a recently legislated process that provides for detailed mineral resource assessments in candidate park areas has stimulated the creation of a mineral potential classification system for use in land-use planning and policy decisions.A mineral potential study of the Chilko Lake Planning Area provided three unique categories of field data on which to build the classification system. These categories are geological setting, geochemistry, and mineral occurrences. Data in each category were compiled independently to provide indicators of mineral potential. The field data were used to develop a widely understood classification of mineral potential. The classification is based on two factors: favorability and degree of confidence.  相似文献   

Determination of the hydrogen content of synthetic quartz by neutron polarization analysis     

O. Moze  T. J. Hicks  A. C. McLaren 《Physics and Chemistry of Minerals》1980,5(4):309-314

Neutron polarization analysis has been used for the quantitative determination of hydrogen in a crystal of synthetic quartz. The observed weighted average value of 1860±950 H/10⁶Si is in good agreement with the value determined from infrared absorption.  相似文献   

The twinning microstructure and growth of amethyst quartz     

A. C. McLaren  D. R. Pitkethly 《Physics and Chemistry of Minerals》1982,8(3):128-135

The characteristic lamellar-twinning of the right-handed (R) and left-handed (L) structures in the major rhombohedral growth sectors of amethyst quartz has been studied by optical techniques, X-ray topography and transmission electron microscopy (TEM). The TEM observations show that the region of each Brewster fringe consists of fine-scale Brazil twin lamellae parallel to one of the r, z{10 \(\overline {\text{1}} \) 1} planes, and structural considerations suggest that it is one of the r-planes. The twin boundary corresponding to a Brewster fringe has the form of a zig-zag structure consisting of Brazil twin boundaries on two r{10 \(\overline {\text{1}} \) 1} planes, with one predominating. The Brewster fringes appear black between crossed polarizers because light travelling along the optic axis [001] passes through almost equal distances of R and L quartz, giving essentially zero optical rotation. From the visibility of the Brazil twin boundaries in electron micrographs and the visibility of the Brewster fringes in X-ray topographs, the fault vector R and the corresponding composition plane of the major Brazil twin associated with each Brewster fringe has been determined. The streaking of the Brewster fringes observed optically and in the X-ray topographs appears to be due to the stair-rod dislocations at the intersections of the Brazil twin boundaries. Experiments in which synthetic quartz was grown hydrothermally on untwinned seeds and on twinned amethyst seeds showed that the initiation of Brazil twins and the development of Brewster fringes was dependent upon the presence of iron in the growth solution.  相似文献   

Dislocations associated with optical features in naturally-deformed olivine     

J. N. Boland  A. C. McLaren  B. E. Hobbs 《Contributions to Mineralogy and Petrology》1971,30(1):53-63

Transmission electron microscopy has been used for the direct observation of dislocations in naturally-deformed olivine. The dislocations are arranged in arrays forming low-angle sub-boundaries which have been identified with features observed in the optical microscope. Comparison of this dislocation substructure with that observed in olivine, and in metals, experimentally deformed under various conditions, suggests that the deformation in nature has occurred by creep. Possible mechanisms of creep, involving the cooperative glide and climb of dislocations, are discussed.  相似文献   

Two-dimensional lattice images of stacking disorder in wollastonite     

J. L. Hutchison  A. C. McLaren 《Contributions to Mineralogy and Petrology》1976,55(3):303-309

Two-dimensional lattice images of low-temperature triclinic wollastonite (-CaSiO₃) indicate that two types of stacking disorder occur: (1) simple stacking faults and (2) twinning which also involves displacement in the composition plane. Both types of defect produce very similar structures with monoclinic symmetry (parawollastonite). Dislocations are involved at the termination of lamellae of parawollastonite in a triclinic matrix and a model for the dislocation core is proposed.Now at the Edward Davies Chemical Laboratories, Aberystwyth, SY23 1NE, U.K.  相似文献   

A transmission electron microscope study of naturally deformed orthopyroxene     

A. C. McLaren  M. A. Etheridge 《Contributions to Mineralogy and Petrology》1976,57(2):163-177

A model is proposed for the production of clinopyroxene lamellae in orthopyroxene by a dislocation mechanism based on simple shear. Four possible shears are described. Two shears apply to each subcell of orthopyroxene, one with =13.3° in one sense, the other with =18.3° in the opposite sense.The senses of shears of the same magnitude in adjacent cells are also opposite. All shears produce the same structure, but in two discrete orientations which can be distinguished from electron diffraction patterns. However, the operative shear cannot be uniquely determined from the diffraction patterns alone. The characteristics of the diffraction contrast fringes and associated partial dislocations observed by transmission electron microscopy in a naturally deformed orthopyroxene are shown to be consistent with the proposed model.  相似文献   

The changing dietary habits of nineteenth‐century Australian explorers     

William Cooper  Glen McLaren 《The Australian geographer》1997,28(1):97-105

In the first decade of white settlement in New South Wales, ground exploration was limited by the critical shortage of horses and the inability to live off the land. Bush skills were lacking and muskets were extremely inaccurate. Subsequently, the introduction of kangaroo dogs, the willingness to consume even the least appetising animals, and the identification of edible native plants made explorers less dependent on what they could carry. Such skills were to become largely irrelevant after 1840, as fully mounted expeditions began to penetrate the interior, where game was scarce and there was no time for hunting.  相似文献   

Behaviour of diesel fuel on a high energy beach     

Patrick McLaren 《Marine pollution bulletin》1985,16(5):191-196

On 1 March 1984, a spill of diesel fuel and gasoline on the east coast of the Queen Charlotte Islands, Canada, resulted in significant contamination of the beach. Sediment and water samples analysed for oil concentration indicated that oil moved through the beach sediments in response to the tidal cycle and the subsequent changing water table levels. Concentrations tended to be low and variable in samples collected during a flood tide as the oil was driven through the sediments to the upper beach face. On the ebb, however, concentrations increased nearly five times as oil was released from the lowering water table onto the surface of the beach face. At low tide some residual oil remained trapped in the sediments, the amount correlating with the degree of sediment sorting (i.e. sediment porosity). In spite of high wave exposure, traces of fuel remained within 300 m of the spill site after 60 days. This suggests that light, unweathered oil is not mechanically abraded and dispersed in the same manner as more weathered oil; rather the light oil is released from the beach sediments principally during an ebbing tide, and wave action probably affects the cleaning of the beach in a minor capacity.  相似文献   

Sediment transport trends and cross-sectional stability of a lagoonal tidal inlet on the Central Coast of Vietnam     

Do Minh Duc  Tran Thanh Tung  Patrick McLaren  Tran Ngoc Anh  Dinh Thi Quynh 《国际泥沙研究》2019,34(4):322-334

Lagoonal tidal inlets are a typical morphology of the Central Coast of Vietnam. Recently, navigation channels in these inlets have become increasingly threatened by siltation. This study analyses the relations between sediment distribution and transport trends (using the technique of Sediment Trend Analysis-STA■) in the lagoonal system of the De Gi inlet and then proposes appropriate countermeasures against sand deposition in the navigation channel. The STA identified three types of transport trends in the De Gi inlet, namely dynamic equilibrium, net accretion, and net erosion. Processes associated with the tidal prism have resulted in trends of sediment transport and deposition across the flood and ebb tidal shoals, which maintain a present cross-sectional area of about 1000m^2. However, longshore sediment transport from north to south resulting from northeast waves cause additional sand deposition in the channel. In addition, the effects of refraction associated with a nearby headland and jetty also increase sedimentation. These processes provide the main reasons for sediment deposition in the De Gi inlet. Short term and regular dredging helps to maintain the navigation channel. A system comprised of three jetties (north, south, and weir) is necessary to ensure the longterm cross-sectional stability of the navigation channel.  相似文献   

Bushmanship: The explorers' silent partner     

J.M.R. Cameron  Glen McLaren  William Cooper 《The Australian geographer》1999,30(3):337-353

Bushmanship, or the competence to interact meaningfully with newly encountered environments in the achievement of predetermined goals, is a factor overlooked in analyses of land-based exploration. The importance of bushmanship is examined in this paper through a comparison of George Grey's inept exploration of north-western Australia in 1836-37 with Edward Eyre's increasingly successful overlanding ventures in south-eastern Australia at approximately the same time. Grey's impetuosity, inexperience and lack of competence contrast sharply with Eyre's growing confidence to handle unfamiliar conditions. The comparison reveals many of the factors that differentiate externally initiated expeditions such as Grey's from forays by settlers determined to wrest a living from newly settled territories.  相似文献