摘要:

Three types of groundwater occur in the area of the Ranger mine. Type A groundwater occurs in the loose sands and gravels occupying the present day stream channels, Type B in the weathering profile and Type C occurs in relatively fresh fractured bedrock occupying open fractures and other cavities. The three types of groundwater can be distinguished both chemically and isotopically. Light stable isotope data suggest that most early rains are lost by evapotranspiration and have no imprint on the groundwater. Later in the wet season, the ground is saturated and groundwater recharge occurs on a regional scale. This younger groundwater sits on the older waters. Mixing is probably minimal as before any large scale mixing could occur, most younger waters are lost by evapotranspiration. Stable isotope data suggest that Type B groundwater in certain areas has some connection with evaporated surface water bodies. Stable isotope measurements for the pollution monitoring bores around the tailings dam do not indicate any connection with the polluted pond waters at the time of sample collection.

ISSN:0812-0099    

DOI:10.1080/08120098608729379

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The Beltana earthquake of 29 December 1983 occurred in the North Flinders Ranges, one of the most seismically active parts of South Australia. Although earthquakes in this region may be associated with a north‐south chain of diapirs, the structural relationship between the earthquake and the diapirs is not clear. The main Beltana earthquake was associated with two foreshocks and 16 aftershocks. The trend of this sequence (319 ± 4°) is consistent with the focal mechansim, which indicates a northwest‐trending left‐lateral strike‐slip fault caused by eastwest compression. The axis of maximum compression is similar to those obtained from six other South Australian earthquakes (McCue & Sutton 1979; Singh 1985). However, the trend of the sequence does not appear to relate to the surface geometry of the Beltana Diapir, which is intersected by the earthquake sequence. The main earthquake was recorded throughout the Australian continent. A least squares analysis of the first arrivals gives a Pnvelocity of 8.28 ± 0.02 km/s in the 170–1250 km range, and a velocity of 8.82 + 0.07 km/s, beyond 1400 km. These results are consistent with data obtained earlier (Denhamet al1972) from the Ord River explosions for central and Western Australia. The magnitudes of the main earthquake were 5.1 mband 4.4 MLand seismic moment was about 1 x 1016N‐m. The earthquake was felt over an area of about 15 000 km2. A maximum intensity of MM VI was experienced in the Beltana/Parachilna region, where several reports were received of wall and ceiling plaster being cracked and displaced.

ISSN:0812-0099    

DOI:10.1080/08120098608729380

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Felsic volcanic rocks in the northeastern Yilgarn Block form two major groups with distinctive petrochemical characteristics and tectonic settings. Discrete calc‐alkaline volcanic centres composed predominantly of andesite were formed during the development of a major volcano‐sedimentary basin and were erupted contemporaneously with tholeiitic basalt. Parental calc‐alkaline melts were derived by shallow, hydrous partial melting of LIL‐enriched mantle; Y‐ and HREE‐depleted, Sr‐enriched dacitic volcanic rocks and dacite to rhyolite undepleted in Y and HREE and depleted in Sr associated with andesite in some of the volcanic centres were derived from an intermediate parent by crystal fractionation involving variable proportions of the modal minerals. Calc‐alkaline volcanism is believed to have been triggered by “hot spot’ activity rather than subduction. Rhyolite enriched in Zr, Nb, Y and HREE was deposited in a linear trough in a tectonic zone which disrupted the western margin of the volcano‐sedimentary basin. The rhyolite contains no associated andesite and is considered unlikely to have formed by the fractionation of an intermediate parent. A crustal source, tapped during the initial phase of a period of increased crustal extension, is considered most likely. Both varieties of felsic volcanic rock are spatially associated with distinctive, and probably genetically related, plutonic suites. The calc‐alkaline volcanic rocks are intruded by contemporaneous, cogenetic hornblende‐bearing granodiorite porphyry and are spatially associated with numerous younger plutons of hornblende‐bearing granodiorite to monzogranite of probable calc‐alkaline affinity. Rhyolitic volcanic rocks are believed to be cogenetic with high‐level plutons of syenogranite to alkali feldspar granite.

ISSN:0812-0099    

DOI:10.1080/08120098608729381

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Chemical and radiometric analyses have been made on core samples from 15 drill holes intersecting the Toolebuc Formation at Julia Creek. The holes are located in the vicinity of the St Elmo Structure and include intersections of a potentially economic oil shale deposit west of this structure as well as non‐economic mixed coquinite/shale intersections to the east. The gamma ray activity of the formation is due largely to uranium in the shales. Wire‐line gamma ray logs, available for eight of these holes, reflect the distribution of organic carbon. Despite this, there is poor correlation between uranium and organic carbon in the oil shales as a result of remobilization of uranium from organic matter into phosphate during diagenesis. In consequence wire‐line gamma ray logs have no potential for evaluating oil yield. Density, on the other hand, is a good indicator of oil potential. On a hole by hole basis, the correlation between uranium and organic carbon in the formation ranges from 0.22 west of the St Elmo Structure (the potential oil shale resource) to 0.95 east of the structure. This reflects a systematic change in sedimentology from oil shale that is thick and well separated from coquinite (low correlation) to laterally equivalent but finely interbedded coquinite and shale (high correlations). Such trends could be used in exploratory drilling to indicate favourable areas elsewhere in the Toolebuc Formation.

ISSN:0812-0099    

DOI:10.1080/08120098608729382

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Stratiform manganese silicate rocks overlie jasper and metabasah in the ?Middle Silurian Hoskins Formation at the Hoskins manganese mine near Grenfell, NSW. Two dominant mineral assemblages occur in the Mn silicate rocks: (1) a “reduced’ assemblage, probably gradational into underlying jasper, containing abundant rhodonite and/or tephroite, plus subordinate carbonates, quartz, hausmannite, spessartine and Ba minerals, and (2) a well‐laminated ‘oxidized’ assemblage rich in red Mn‐rich alkali pyroxene and amphibole, braunite, manganoan pectolite and minor Mn‐rich mica, alkali feldspars, carbonates, quartz and barite. Several Mn silicates implicitly contain trivalent Mn. The Mn silicate rocks are rich in Mn, Ba and Sr, and also contain anomalously high Co, Cu, As and W; oxidized assemblages are alkali‐rich. Bulk compositions and geological setting suggest a submarine volcanic exhalative origin for the precursors of the Mn silicate rocks and jasper. Metamorphism has occurred at upper greenschist facies with original high oxygen fugacity conditions in the exhalative sediments being largely reflected in the resulting assemblages. Although analogues of the reduced Mn silicate rocks are widespread in metamorphosed Mn deposits, equivalents of the oxidized assemblages appear to be particularly uncommon.

ISSN:0812-0099    

DOI:10.1080/08120098608729383

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Epithermal Ag‐Au mineralization is widespread within the Late Permian Drake Volcanics. The deposits are of three main types: fissure lodes, stockworks, and disseminations. The primary mineralization consists of silver sulphosalts and native metal alloys, with associated base metal sulphides and pyrite, and is generally contained within larger silicate ± pyrite alteration zones. Both alteration and mineralization are multistage, typically with an early barren or low grade sericite‐clay assemblage overprinted by later ore‐associated quartz ± K feldspar alteration. Permeable host rocks and the presence of a structural feeder zone are features common to all the deposits studied in detail, along with a close spatial relationship with felsic intrusive phases of the Drake Volcanics. A second episode of Ag‐Au mineralization is associated with the Permo‐Triassic granitoids of the region. These occurrences are generally of the fissure lode style, and can be distinguished from the volcanic‐associated mineralization on the basis of their distinctive ore mineral assemblage and lead isotopic composition.

ISSN:0812-0099    

DOI:10.1080/08120098608729384

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In the Goodmans Ford‐Bullio area NSW an adamellite granodiorite pluton and several small previously undocumented tonalite plutons hosting orbicular xenoliths, are intruded into dacitic ash flows and rhyodaeitic lavas of the northern part of the Early Devonian Bindook Volcanic Complex. These plutons are shown to be satellite plutons of the Early Devonian Marulan Batholith and have been passively emplaced along fractures or faults in the host volcanics by collapse of the roof volcanics, possibly following magma withdrawal during eruption. Reconnaissance fieldwork indicates substantial volumes of intrusive rocks to the north and west of the Goodmans Ford‐Bullio area. A comagmatic relationship between the Bindook Volcanic Complex and the Marulan Batholith, suggested by their close spatial and temporal association, is supported by petrological and chemical data.

ISSN:0812-0099    

DOI:10.1080/08120098608729385

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The Saddleback Group is a volcanogenic greenstone sequence developed in the Western Gneiss Terrain of the Archaean Yilgarn Block. It consists of three major units; the Hotham Formation composed mainly of metasediments, the Wells Formation consisting of metamorphosed felsic volcanics and the Marradong Formation which is made up of metabasalts. The sequence has been metamorphosed to greenschist facies and intruded by adamellite.

ISSN:0812-0099    

DOI:10.1080/08120098608729386

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The final deformation in a polydeformed unit of Ordovician turbidites along the NSW south coast, produced kinks at scales from centimetres (mesoscopic kinks) to kilometres (megakinks). At the outcrop‐scale, crenulation cleavages and fractures also developed. The mesoscopic kinks are of the reverse type, have orthorhombic to monoclinic symmetry and generally show a small dilation of the kink short‐limb. An S3crenulation cleavage is associated with the kinks and shows variable morphology and orientation. The kinks are interpreted to have formed by a modified “kink rotation model’, in which kink‐band foliation shortens during kink formation. The mesoscopic kink geometry does not uphold both the kink proportion compressional analysis and the conjugate kink bisector method for determining the axis of principal compression. Nevertheless, both methods suggest that the mesoscopic kinks predate the megakink rotation.

ISSN:0812-0099    

DOI:10.1080/08120098608729387

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Richter magnitudes MLhave been determined for 718 well recorded South Australian earthquakes by converting amplitudes derived from existing seismograph stations to equivalent Wood‐Anderson amplitudes, and substituting in Richter's formula (Richter 1935), derived for such instruments and for Southern California. The magnitudes so determined were generally found to increase with distance A for each earthquake, at least for events at distances below a few hundred kilometres, reflecting lower attenuation of crustal S waves in South Australia.

ISSN:0812-0099    

DOI:10.1080/08120098608729388

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor