Academic literature on the topic 'Geology, Structural South Australia Olary Region'

The Barrow and Dampier Sub-basins of the Northern Carnarvon Basin developed by repeated reactivation of long-lived basement structures during Palaeozoic and Mesozoic tectonism. Inherited basement fabric specific to the terranes and mobile belts in the region comprise northwest, northeast, and north–south-trending Archaean and Proterozoic structures. Reactivation of these structures controlled the shape of the sub-basin depocentres and basement topography, and determined the orientation and style of structures in the sediments.The Lewis Trough is localised over a reactivated NEtrending former strike-slip zone, the North West Shelf (NWS) Megashear. The inboard Dampier Sub-basin reflects the influence of the fabric of the underlying Pilbara Craton. Proterozoic mobile belts underlie the Barrow Sub-basin where basement fabric is dominated by two structural trends, NE-trending Megashear structures offset sinistrally by NS-trending Pinjarra structures.The present-day geometry and basement topography of the basins is the result of accumulated deformation produced by three main tectonic phases. Regional NESW extension in the Devonian produced sinistral strikeslip on NE-trending Megashear structures. Large Devonian-Carboniferous pull-apart basins were introduced in the Barrow Sub-basin where Megashear structures stepped to the left and are responsible for the major structural differences between the Barrow and Dampier Sub-basins. Northwest extension in the Late Carboniferous to Early Permian marks the main extensional phase with extreme crustal attenuation. The majority of the Northern Carnarvon basin sediments were deposited during this extensional basin phase and the subsequent Triassic sag phase. Jurassic extension reactivated Permian faults during renewed NW extension. A change in extension direction occurred prior to Cretaceous sea floor spreading, manifest in basement block rotation concentrated in the Tithonian. This event changed the shape and size of basin compartments and altered fluid migration pathways.The currently mapped structural trends, compartment size and shape of the Barrow and Dampier Sub-basins of the Northern Carnarvon Basin reflect the “character” of the basement beneath and surrounding each of the subbasins.Basement character is defined by the composition, lithology, structure, grain, fabric, rheology and regolith of each basement terrane beneath or surrounding the target basins. Basement character can be discriminated and mapped with mineral exploration methods that use non-seismic data such as gravity, magnetics and bathymetry, and then calibrated with available seismic and well datasets. A range of remote sensing and geophysical datasets were systematically calibrated, integrated and interpreted starting at a scale of about 1:1.5 million (covering much of Western Australia) and progressing to scales of about 1:250,000 in the sub-basins. The interpretation produced a new view of the basement geology of the region and its influence on basin architecture and fill history. The bottom-up or basement-first interpretation process complements the more traditional top-down seismic and well-driven exploration methods, providing a consistent map-based regional structural model that constrains structural interpretation of seismic data.The combination of non-seismic and seismic data provides a powerful tool for mapping basement architecture (SEEBASE™: Structurally Enhanced view of Economic Basement); basement-involved faults (trap type and size); intra-sedimentary geology (igneous bodies, basement-detached faults, basin floor fans); primary fluid focussing and migration pathways and paleo-river drainage patterns, sediment composition and lithology.

Figure 5.13 is folded and in plastic pocket inside back cover.
Bibliography: leaves 147-168.
xiv, 184, [14] leaves, [35] leaves of plates : ill. (chiefly col.), maps ; 30 cm.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1998

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A structural study of Palaeoproterozoic Willyama Supergroup rocks to the southeast of Old Boolcoomata approximately 20 kilometres north of Olary, South Australia, discloses a complex history of deformation. This includes an axial planar S1 schistosity and several intersecting locally developed subsequent planar fabrics. The main findings support previous unpublished company studies. Structural maps were produced at various scales in areas surrounding the ‘Woman-in-White’ amphibolite and all available observations were used to form a chronology of events and tectonic model for the geometric and kinematic evolution of the area. In a domain east of the 'Woman-in-White' amphibolite the S1 is parallel to the axial plane of a major isoclinal synform closing to the east. S2 is axial planar to tight to open class 2 and class 1c F2 folds that trend generally north to northeast. Regionally, and particularly in the vicinity of the 'Woman-in-White' amphibolite, a third deformation is very intensely developed generating two fabrics. The S3 schistosity is the axial planar fabric to tight to isoclinal F3 folds trending consistently east-west. The S3 fabric is also expressed as a crenulation of the S1 regional schistosity. These pre-Adelaidean structural elements are recognised as comprising the Olarian Deformation. Fold interference is present on all scales. Olarian deformation events two and three have given the flat lying western limb of the principal F1 synform a luniform, dome and basin morphology. Type 2 and type 3 interference patterns are the most common in the area mapped. The occurrence of the two interference patterns is due to the variable angle between OD2 and OD3 compressions, which is commonly approximately 40 in the west-southwest part of the mapped area. This work conforms closely in complexity to previous regional studies and has been supplemented by other new investigations of an important northeast-southwest trending shear zone corresponding to OD3, lying further to the north, and a geochemical investigation of the 'Woman-in-White' amphibolite indicating its probable mantle origin and possible emplacement before all deformations occurred.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1999

"Two independent geochronological techniques specifically targeting post-kinematic or late-stage growth of kyanite, staurolite and late-stage garnet in the southern Curnamona Province has found that these minerals grew during the Delamerian Orogeny (~530-500 Ma). Prograde metamorphism during the Delamerian Orogeny attained kyanite-staurolite-garnet grade (amphibolite-facies). Previous interpretations of an anticlockwise P-T path for the Olarian Orogeny need revising, as these interpretations have been shown in this study to be based on textural relationships spanning ~1100 million years. This highlights the importance of in situ geochronological techniques in defining robust P-T-t paths for a region." --p. 121 of source document.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2006.

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The Onkaparinga Gorge, situated on the Onkaparinga River southwest of Clarendon contains exposed middle Adelaidean rocks of the southern Adelaide Fold Belt. The structural geometry displayed exists as the result of a Cambro-Ordovician compressional deformation, the Delamarian Orogeny. Folds are gentle in competent strata and close to tight and west vergent in fine grained incompetent strata. The majority of faulting is thrusting oriented subparallel to bedding with one high angle thrust, the Onkaparinga Fault that cross­cuts all other tectonic elements. Low angle thrusting caused the repetition of competent beds and the duplexing or imbrication of incompetent units. Total displacement calculated by the addition of all minimum displacements measured on individual thrusts is in the order of 1.8 kilometres. Strain patterns indicate that thickening of bedding has occurred in the Sturt Formation diamictite with considerable shortening and volume loss due to compaction. The style of deformation in the Belair Subgroup is one of stretching parallel to bedding. The difference in strain patterns in the two above mentioned formations suggests that there is a structural discontinuity between the Belair Subgroup and the Sturt Formation. Evidence from geological mapping and subsequent stereographic projections of field data indicates that thrusting subparallel to bedding has been the major deformational influence at the levels of the Sturt and Tapley Hill Formations with folding less influential. This evidence may support the existence of a roof thrust zone at this level but such features can also be attributed to other deformational models. Two models of tectonic evolution can explain the current structural geometry in the Onkaparinga Gorge. The first model associates the thrusting observed with fold development during compression. The second model proposes a two-part deformation of thrusting followed by folding of the thrusted strata during continued compression.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1993

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In the central part of the eastern Weekeroo Inlier, Olary Domain, two types of granite have been identified. This thesis explores both granite types in order to explain possible tectonic environments and geological evolution during the Proterozoic. The A-type Walter Outalpa granite is characterised by high Si02, Zr, Nb, Y, rare earth elements (REE) and low MgO, CaO, Ti02, P205 and light field strength elements (LFSE). High zircon saturation temperatures differentiate this fractionated A-type granite from potential fractionated I-type granites. The peraluminous granite is characterised by high Si0, Al203, Rb, U, Th, and low MgO, CaO, Ti02, Sr and light REE. It displays strong geochemical similarities to the Bimbowrie S-type granite. Consistent geochemical and isotopic characteristics for the Walter Outalpa granite and other similar A-type granites across the Olary Domain indicate a single regional crustal plus mantle source. Partial melting of lower Archaean crust due to lithospheric thinning is proposed. Geochemistry and isotopic analysis of the peraluminous granites suggest varying infracrustal sources for loosely grouped S-type granites in the Olary Domain. Previous interpretations for the depositional environment of the Willyama Supergroup metasediments in a continental rift setting are supported by comagmatic A-type volcanics and granites within the central part of the eastern Weekeroo Inlier. An extensional environment during emplacement is consistent with evidence for shallow level emplacement such as graphic texture, and the absence of a contact aureole for the Walter Outalpa granite. There is foliation development and evidence of folding for three deformation events during the Proterozoic Olarian Orogeny. Timing relationships between granitoids and metasediments in this area have constrained relative timing of emplacement. Low temperature solid state deformation affected the A-type Walter Outalpa granite after emplacement into Willyama Supergroup metasediments. Crosscutting relationships between the peraluminous granite and adjacent deformed metasediments imply a late to post D2 emplacement for this granite.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 1998