Tailgate stability within longwall coal mining is critical to longwall productivity and safety of mine personnel. A mechanistic model was developed and tested to explain observed high deformation tailgate behaviour characterised by lateral strata movement. Field investigations were conducted at three Australian longwall mines with an emphasis on the measurement of; horizontal strata movement about gateroads during longwall extraction, and the load/deformation characteristics of standing supports. 3D numerical modelling was used to simulate tailgate deformation, and interaction of various support types and design strategies. The sensitivity of strata and support behaviour to; variations in roof geology, strength of sliding interfaces, depth of cover, pre-mining horizontal stress magnitude and orientation, and strength and stiffness characteristics of standing supports was modelled. Laboratory investigations of a standing support product, the ???Can???, at reduced scale (one third) were conducted. The tests determined the loading mechanics of the product and provided a basis for optimisation of the engineering properties (strength and stiffness). Horizontal strata movement about longwall extraction was found to have a significant impact on strata behaviour at two of the three mines investigated. The term ???skew roof??? was coined to describe the deformation process. Essentially the roof strata was found to ???skew??? towards the approaching goaf. The key geotechnical factors found to control the skew roof mechanism were; magnitude and orientation of the pre-mining horizontal stress, presence of weak interfaces along which sliding could occur, and shear strength of the interfaces. Measurement of the nature and extent of skew roof deformation specific to each mine provided a sound engineering basis for support design. These included; the relative roles of long tendons versus standing support, optimal pattern (position across and along the roadway) of standing supports, and appropriate strength and stiffness characteristics. The findings were successfully implemented at Metropolitan Colliery in particular, where adequate tailgate serviceability has been achieved within a high deformation environment, and whilst maintaining a relatively small chain pillar width. The research has achieved an alternative to empirical and trial and error tailgate support design methods.

This thesis presents the results of a detailed study of the mineralogy and paragenesis of gold at the Sunrise Dam gold deposit. The Sunrise Dam mine is the largest gold deposit in the Archean Laverton Tectonic Zone of the Eastern Goldfields Province, Yilgarn Craton, Western Australia. A number of previous studies have established the geology, geochemistry and geochronology, but the nature of the gold mineralogy and distribution has remained poorly characterized. Mineralogical studies have established a paragenetic sequence consisting of five hydrothermal stages (D1, D2, D3, D4a and D4b) which are generally in accord with the major deformation events at Sunrise Dam gold deposit. The D4a stage was the dominant episode of Au deposition, followed, in importance by the D4b stage, which is characterized by more diverse ore mineralogy including base metal sulfides, sulfosalts, and telluride minerals. Based on EPMA results, native gold in D4a stage has higher purity, with a small range of Ag variations (fineness 923 ~ 977, average 945), than that of the D4b stage (fineness 596 ~ 983, average 899), in which fineness values decrease systematically in accord with mineral paragenesis, reflecting that gold deposition was from a progressively compositionally evolving hydrothermal fluid with respect to Au/Ag ratios. The occurrences of As-rich pyrites are restricted to steeply-dipping ore bodies, which are most likely structurally connected at various level by channel ways through which As-rich (D4a) hydrothermal fluid migrating upward. There is a systematic variation in composition of the tetrahedrite-group minerals ranging from Sb to As end-members with highly variable Zn:Fe ratios, which correlates with the later paragenetic stages (D3, D4a, and D4b) and mineral associations. The composition of the tetrahedrite-group minerals is useful as a petrogenetic indicator of the evolution of the hydrothermal mineralizing systems with time. A total of thirteen telluride mineral species, including two unnamed phases, were identified in the D4 veins. Among them nagyágite, the complex Pb-Sb-Au tellurosulfide is most abundant. The deposit is the second occurrence of this mineral in the Yilgarn Craton. Compositionally, nagyágite from Sunrise Dam conforms to ideal stoichiometry, with negligible As content and Au/(Au+Te) ratio of 0.325. The diverse mineralogy of the post-D4 veinlets relative to the host veins is attributed to small-scale reaction fronts established along zones of replacement. The presence of Au-Ag tellurides in D4 veins and the character of their breakdown products have implications for the gold recovery as well as for the genetic interpretation of the deposit. During the D4b stage, Au-richer telluride and Au-richer native gold mineralization formed earlier than Ag-(Au)-telluride and Ag-richer gold mineralization. Values of f(Te2) and f(S2) for the early telluride assemblages were determined at 300°C to be -10.7 to -7.8 (log fTe2) and 11.4 to -8.6( log fS2 ). The Au content of arsenian pyrite and arsenopyrite from four mineralizing stages (D1, D3, D4a and D4b) was measured using in-situ LA-ICP-MS. The average Au concentration is 44.5 ppm in pyrite (n = 224) with maximum value of 3,067 ppm, and 1,483 ppm in arsenopyrite (n = 35) with maximum value of 5,767 ppm, which are the highest concentrations reported for the Yilgarn Craton. The concentrations of invisible Au in arsenian pyrite at Sunrise Dam varies with mineralizing events, mineral paragenesis, and textural type. Gold is strongly enriched in D4a stage pyrite (average 80.8 ppm) and to a lesser extent in D4b pyrite (average 16.8 ppm). Pyrite from D1 (average 3.55 ppm) and D3 (average 2.96 ppm) show much lower levels of Au enrichment. The presence of metallic Au below the Au solubility limit in the Sunrise Dam pyrite is interpreted as evidence of an epigenetic origin for Au mineralization. Small-scale remobilization during dissolution-reprecipitation (D4a) and recrystallization (post-D4b) processes resulted in the Au enrichment and the upgrading of Au during successive hydrothermal events in the deposit. The speciation of Au at Sunrise Dam and the exceptional size of the deposit are the result of multiple fluid flow and multiple Au-precipitating mechanisms over a single plumbing system.

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains x, 86, [22] p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 58-63).

Thesis (Ph. D.)--Missouri University of Science and Technology, 2008. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 6, 2008) Includes bibliographical references (p. 229-235).

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 81 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references.

Thesis (M.S.)--Ohio University, June, 1988. / Title from PDF t.p.

Thesis (B.A. (Hons))--University of Adelaide, 1989.

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1999. / Includes bibliographical references (leaves 72-75).

Thesis (Ph. D.)--University of New South Wales, 2002. / Includes bibliography. Also available online.