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c. Migrated seismic section for the GOMA (08GA-OM1) seismic line between CDP 23500 and CDP 33859, showing both the uninterpreted and interpreted versions. Provinces, domains, seismic subdomains and key faults are named. The display is to ~60 km depth, and shows the vertical scale equal to the horizontal scale, assuming an average crustal velocity of 6000 m s-1 .
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In 2008, as part of its Onshore Energy Security Program, Geoscience Australia, in conjunction with AuScope, Primary Industries and Resources South Australia (PIRSA) and the Northern Territory Geological Survey, acquired 634 km of vibroseis-source, deep seismic reflection data and gravity data along a single traverse from about 25 km southeast of Er...
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The use of in situ Lu-Hf isotope analysis, in conjunction with high precision SHRIMP II or LAICPMS U-Pb data on zircons, provides information about the age and the crustal evolution of source regions. This approach is particularly informative where there is the potential for multiple and separate events which might have temporal similarities, such...
Citations
... Hand et al., 2007). Furthermore, Direen et al. (2005) suggested a S-vergent fold-thrust belt developed in the northern Gawler Craton at this time, which is imaged in regional seismic reflection data (Korsch et al., 2010a(Korsch et al., , 2010b). ...
The Mount Woods Domain in the Gawler Craton, South Australia records a complex tectonic evolution spanning the Palaeoproterozoic and Mesoproterozoic. The regional structural architecture is interpreted to represent a partially preserved metamorphic core complex that developed during the ~1600–1580 Ma Hiltaba Event, making this one of the oldest known core complexes on Earth. The lower plate is preserved in the central Mount Woods Domain, which comprises the Mount Woods Metamorphics. These rocks yield a detrital zircon maximum depositional age of ~1860 Ma and were polydeformed and metamorphosed to upper amphibolite to granulite facies during the ~1740–1690 Ma Kimban Orogeny. The upper plate comprises a younger succession (the Skylark Metasediments) deposited at ~1750 Ma. Within the upper plate, sedimentary and volcanic successions of the Gawler Range Volcanics were deposited into half graben that evolved during brittle normal faulting. The Skylark Shear Zone represents the basal detachment fault separating the upper and lower plate of the core complex. The geometry of normal faults in the upper plate is consistent with NE-SW extension.
Both the upper and lower plates are intruded by ~1795–1575 Ma Hiltaba Suite granitic and mafic plutons. The core complex was extensively modified during the ~1570–1540 Ma Kararan Orogeny. Exhumation of the western and eastern Mount Woods Domain is indicated by new ⁴⁰Ar/³⁹Ar biotite cooling ages that show that rock packages in the central Mount Woods Domain cooled past ~300 °C ± 50 °C at ~1560 Ma, which was ~20 million years before equivalent cooling in the western and eastern Mount Woods Domain. Exhumation was associated with activity along major syn-Kararan Orogeny faults.
... A common approach to interpretation of crustal seismic reflection profiles relies on subjective identification of faults, which in most cases are identified as discrete and narrow zones of deformation along which crustal movement was accommodated. However, examples of co-located magnetotelluric and seismic reflection profiles in Australia show that particularly in the mid to lower crust sub-vertical zones of high conductivity cross-cut crustal-scale faults interpreted from seismic sections (Korsch et al., 2010;Thiel et al., , 2015Johnson and Thorne, 2011). There is therefore a need to determine whether or not the results of both techniques can be related to the same geodynamic process (Cook and Jones, 1995), and inform on how different types of inter pretation may better link the two data types. ...
... Structural interpretation of seismic reflectors is carried out in a similar fashion to structural mapping of surface geology, with discrete structures being marked at offsets, terminations or change in direction of reflectors . Lithostratigraphic units are interpreted based on seismic character and named when found outcropping or in drillhole intersections, whilst seismic provinces are termed for interpreted packages with no known surface expression or drillhole intersection, and are generally reserved for mid-lower crustal units (Korsch et al., 2010). Typically, interpretations in the style described above (e.g. ...
... Typically, interpretations in the style described above (e.g. Fraser et al., 2010a;Korsch et al., 2010) are appropriate for brittle deformation styles, whilst only limited attention has been paid to ductile deformation in the lower crust (Torvela et al., 2013), pervasive mass transfer or broad scale alteration processes. Drummond et al. (2006) and more recent studies endorse modification of reflectivity as a key characteristic enabling interpretation of post-formational processes such as magma transfer, hydrothermal alteration or ductile shear fabric development Wise et al., 2015c;Dutch et al., 2016). ...
Over the last two decades, co-located seismic and magnetotelluric (MT) profiles provided fundamental geophysical data sets to image the Australian crust. Despite their complimentary nature, the data are processed and often interpreted separately without common processes in mind. We here qualitatively compare 2D resistivity inversion models derived from MT and seismic reflection profiles across a region of Archean–Proterozoic Australia to address the causes of variations in seismic response and anomalous conductivity in the crust. We find that there exists a spatial association between regions of low reflectivity in seismic sections and low resistivity in co-located 2D MT modelled sections. These relationships elucidate possible signatures of past magmatic and fluid-related events. Depending on their diffuse or discrete character, we hypothesize these signatures signify fossil melting of the crust due to mafic underplating, magma movement or hydrothermal fluid flow through the crust. The approach discussed herein is a process-oriented approach to interpretation of geophysical images and a significant extension to traditional geophysical methods which are primarily sensitive to a singular bulk rock property or state.
... The Karari Shear Zone (KSZ) is a major north-east orientated shear zone in the northern Gawler Craton (Figs. 1 & 2) that is sub-vertical in the western Gawler Craton (Rankin et al., 1989). Based on deep crustal reflection seismic data, Korsch et al. (2010) concluded that the KSZ dips to the north to northwest along the southern margin of the Coober Pedy Ridge, with the northern margin of the Coober Pedy Ridge being defined by a splay from the KSZ, called the Horse Camp Fault (Fig. 2). The exact location of the KSZ to the east of the Coober Pedy Ridge is poorly defined as the structure appears to splay into several subsidiary structures and becomes more deeply buried by younger sediment (Rankin et al., 1989;Fraser et al., 2012). ...
The formation of major Palaeoproterozoic and Mesoproterozoic (Cu)-Au deposits at the metal-rich margins of the Gawler Craton, South Australia, has received a lot of attention, however, the relationship between metal occurrences, the exhumation level of the crust and the structural architecture of the craton margins is less clear. Here, we present results from apatite fission track thermochronology applied to basement rocks at the northern margin of the Gawler Craton, revealing a differential cooling history with respect to the Karari shear zone (KSZ). The KSZ is a major shear zone that extends to the Moho in reflection seismic images and has a prolonged history of high-temperature activity during the Paleoproterozoic and Mesoproterozoic. New apatite fission track data show that samples taken to the north of the KSZ record a significant pulse of Carboniferous cooling, in contrast to the Phanerozoic monotonic slow cooling history documented for the area just south of the KSZ. This Carboniferous cooling signal coincides with a sedimentary hiatus between the Neoproterozoic – Devonian Officer Basin and the late Carboniferous to Early Permian Arckaringa Basin, to the north of the KSZ. Therefore, Carboniferous cooling can be linked with exhumation and fault reactivation of the KSZ at that time, which is interpreted to be associated with far-field compression caused by the Alice Springs Orogeny (~450–300 Ma) of central Australia. Following Carboniferous exhumation, a localized thermal overprint was observed in locations associated with Palaeogene palaeochannels.
The extent of Phanerozoic exhumation shows a spatial relation with the location of Au (and/or Cu, Fe) mineralization in the northern Gawler Craton. Areas that were significantly modified by Mesoproterozoic mineralizing events, such as the Olympic IOCG province and the Central Gawler Gold Province, record post-Silurian exhumation histories related to the Alice Springs Orogeny. To the west of these two major mineral provinces, Archaean – early Palaeoproterozoic terranes in the northwestern Gawler Craton with abundant Au (and Cu, Fe) mineral occurrences were not affected by Phanerozoic exhumation and denudation. These relations suggest that the Mesoproterozoic mineralized terranes were more susceptible to Phanerozoic deformation compared to the Archaean – Palaeoproterozoic terranes within the stronger parts of the Gawler Craton. Hence, understanding the timing of fault reactivation and the associated relative exhumation level may provide valuable constraints for ore deposit preservation and mineral exploration within the Gawler Craton.
... From west to east, these are the Nawa, Christie and Wilgena Domains. The eastern end of seismic line 13GA-EG1 is at Tarcoola, which intersects the southern end of the north-south 08GA-OM1 seismic line (Korsch et al., 2010). ...
... The interpretation of the western Gawler Craton part of the seismic line showed an overall westward dipping architecture of the main shear zones (Dutch et al., 2015b). The Moho showed deepening in two places from about 42 km in the east to about 53 km depth under the Nawa and Christie Domains (Kennett and Chopping, 2015). In general, the crust shows three layers: a reflective lower crust; a discontinuous, weakly reflective middle crust; and a moderately reflective upper crust . ...
... The Nawa Domain contains a series of northeast-trending shears that dip to the northwest. Further to the northeast in the Nawa Domain, these structures trend east-west with dips to the north (Korsch et al., 2010;Baines et al., 2011). A series of contrasting magnetic signatures, which range from the very high to the very low, appear to wrap around in a large-scale, tight fold at the southwestern end of the Nawa Domain. ...
This paper highlights the complimentary potential field studies that have been done in parallel to the interpretation of the 13GA-EG1 Eucla-Gawler deep crustal reflection seismic line. Gravity and magnetic images have been interpreted and potential field data has been modelled using edge detection, forward modelling and inversions to pick out the main domains and structures. Seismic, MT and drill core analysis has been progressing in parallel to the potential field investigations. The different approach taken here was to allow more freedom and independence in the interpretations originating from the potential field studies, rather than constraining them with a predefined architecture from the seismic interpretation. Initial results show gravity and magnetic worms correlating with interpreted structures and domain boundaries. Inversions show the 3D distribution of magnetic susceptibility and densities associated with major features such as the Mundrabilla Shear Zone and folded feature seen in the Nawa Domain. This paper summarises the main findings from the potential field studies, which, in conjunction with the parallel studies, allows for a more robust understanding of the crustal architecture and assessment of the mineral potential of the region.
... These metasedimentary and meta-igenous rocks are interpreted to overlie or intrude an older basement (Daly et al., 1998), which comprises c. 1920 Ma and c. 2460 Ma orthogneiss (Fanning et al., 2007; Howard et al., 2011b; Reid et al., 2014a). Geophysical data reveal that rocks of the Nawa Domain are deformed by a series of north-east trending structures that are predominantly north-dipping (Korsch et al., 2010; Baines et al., 2011). At least some of the north-dipping structures likely formed during development of the Paleoproterozoic basin, with these basin-bounding structures being reactivated during the Kimban and Kararan orogenic events (Daly et al., 1998; Payne et al., 2008; Betts et al., 2010; Fraser et al., 2012; Cutts et al., 2013), and again during the reworking associated with shear zone reactivation at c. 1450 Ma (Fraser and Lyons, 2006). ...
... At least some of the north-dipping structures likely formed during development of the Paleoproterozoic basin, with these basin-bounding structures being reactivated during the Kimban and Kararan orogenic events (Daly et al., 1998; Payne et al., 2008; Betts et al., 2010; Fraser et al., 2012; Cutts et al., 2013), and again during the reworking associated with shear zone reactivation at c. 1450 Ma (Fraser and Lyons, 2006). The Coober Pedy Ridge Domain is also present in the northern Gawler Craton and is located between the Karari Shear Zone and the Horse Camp Fault (Fig. 1) and represents a pop-up structure formed during deformation on these crustal scale shear zones (Korsch et al., 2010). The Coober Pedy Ridge Domain comprises metasedimentary and meta-igneous rocks with virtually identical characteristics to similar rocks of the Nawa and Fowler domains (Daly et al., 1998), being dominantly clastic sediments formed at c. 1750 Ma and intruded by c. 1730 Ma mafic and felsic igneous rocks (Fanning et al., 2007). ...
... In 2008, Geoscience Australia, in conjunction with AuScope, Primary Industries and Resources South Australia (now the Geological Survey of South Australia) and the Northern Territory Geological Survey, acquired 634 km of vibroseis-source, 75-fold, deep seismic reflection data to 20 s TWT, providing an image of the crust and upper mantle to a depth of ca 60 km. This was a single north-south traverse from about 25 km southeast of Erldunda in the southern Northern Territory to near Tarcoola in central South Australia (Figs. 3, 7) (Costelloe and Holzschuh, 2010;Korsch et al., 2010b). The traverse, 08GA-OM1, followed the Adelaide to Alice Springs railway line, utilising the railway access road, and is referred to as GOMA, as it traversed the northern Gawler Craton, eastern Officer Basin, eastern Musgrave Province and the southern Amadeus Basin (Fig. 7). ...
... The Woodroffe Thrust, at CDP 32370, is a south-dipping, planar fault which cuts the entire crust. Korsch et al. (2010b) interpreted the thrust to extend to a depth of about 16 s TWT (~48 km). At this locality, it is a basement structure forming the crustal boundary between the Musgrave Province and the Warumpi Province (Korsch et al., 2010b). ...
For over 35 years, deep seismic reflection profiles have been acquired routinely across Australia to better understand the crustal architecture and geodynamic evolution of key geological provinces and basins. Major crustal-scale breaks have been interpreted in some of the profiles, and are often inferred to be relict sutures between different crustal blocks, as well as sometimes being important conduits for mineralising fluids to reach the upper crust. The widespread coverage of the seismic profiles now allows the construction of a new map of major crustal boundaries across Australia, which will better define the architecture of the crustal blocks in three dimensions. It also enables a better understanding of how the Australian continent was constructed from the Mesoarchean through to the Phanerozoic, and how this evolution and these boundaries have controlled metallogenesis. Starting with the locations in 3D of the crustal breaks identified in the seismic profiles, geological (e.g. outcrop mapping, drill hole, geochronology, isotope) and geophysical (e.g. gravity, aeromagnetic, magnetotelluric) data are used to map the crustal boundaries, in plan view, away from the seismic profiles. For some of these boundaries, a high level of confidence can be placed on the location, whereas the location of other boundaries can only be considered to have medium or low confidence. In other areas, especially in regions covered by thick sedimentary successions, the locations of some crustal boundaries are essentially unconstrained, unless they have been imaged by a seismic profile. From the Mesoarchean to the Phanerozoic, the continent formed by the amalgamation of many smaller crustal blocks over a period of nearly 3 billion years. The identification of crustal boundaries in Australia, and the construction of an Australia-wide GIS dataset and map, will help to constrain tectonic models and plate reconstructions for the geological evolution of Australia, and will provide constraints on the three dimensional architecture of Australia. Deep crustal-penetrating structures, particularly major crustal boundaries, are important conduits to transport mineralising fluids from the mantle and lower crust into the upper crust. There are several greenfields regions across Australia where deep crustal-penetrating structures have been imaged in seismic sections, and have potential as possible areas for future mineral systems exploration.
... Further south, at the Red Bank zone also of Alice Springs age, earlier seismic reflection work with explosive sources (Goleby et al. [17]) imaged a major upward displacement of the Moho from around 45 km to 25 km in the hanging wall of the Red Bank thrust that brings lower crustal material to the surface, whilst the Moho in the footwall lies at about 50 km. Comparable displacements of the Moho are seen beneath the Musgrave province on the 2008 GOMA line linking from the Gawler craton through the Officer basin to the Musgrave province and on into the Amadeus basin (Korsch et al. [21]). ...
... A number of reflection profiles have been carried out in the South Australian craton with both east-west and north-south profiles in both the Gawler province [21][22][23] and the Curnamona province [24]. We have selected examples from the Gawler province and its margin, and a north-south profile in the Curnamona craton. ...
The transition between the crust and mantle across the Australian continent shows considerable variations in both depth and sharpness. Recent extensive seismic reflection profiling provides a comprehensive data set to investigate the nature of the Moho in a wide range of geological environments. In reflection seismology the crust is normally characterized by distinct reflectivity whose base is taken as the location of the reflection Moho. This attribution to the base of the crust ties well to refraction and receiver function studies that make a more direct estimate of the depth to the base of the crust. The character of the reflection Moho varies widely across the Precambrian areas of Australia with no consistent link to the surface geology or the estimated age of the crust. In a number of places a double Moho is preserved with underthrusting, suggesting that the reflection Moho is a very ancient feature (at least 1400 Ma in the Capricorn Orogen). Elsewhere, the current Moho reflects multiple generations of crustal reworking.
... About 500 km to the east, the Woodroofe Thrust was crossed by the deep seismic profile 08GA-OM1, where it forms the northern margin to the eastern Musgrave Province (Korsch et al., 2010b). Here the Musgrave Province consists of a two-layered crust, with a reasonably reflective upper crust and a weakly reflective lower crust, similar to the west Musgrave Province and the Tikelmungulda Seismic Province interpreted in the YOM seismic section. ...
... There, the crust is much thinner, however, only about 12 s TWT (~36 km) thick under the Musgrave Province. Nevertheless, the orientation and geometry of the Woodroffe Thrust is very similar in both seismic lines, with the Moho also being displaced by a similar amount (compare Figure 5 with Korsch et al., 2010b). ...
... It is probable that part of the Gawler Craton is the basement beneath the Adelaide Rift Complex. Likewise, the northern and western boundaries coincide with deep burial by Neoproterozoic–Paleozoic successions of the Officer Basin (Korsch et al., 2010). The nature of the boundary between the Gawler Craton and the adjacent c. 1600– 1080 Ma Musgrave Province to the north (Figure 1) is poorly understood. ...
... Nevertheless, the Musgrave Province is composed of isotopically more juvenile material (Wade et al., 2008) and cannot simply be the northern continuation of the Gawler Craton. Deep crustal seismic data reveal crustal-scale north-dipping structures in the northern Gawler Craton, which may form part of a transition zone between the two provinces (Korsch et al., 2010). The southern Gawler Craton is exposed on Eyre and Yorke peninsulas (Figure 2). ...
The Gawler Craton preserves a complex and prolonged tectonic history spanning the interval c. 3200- 1500 Ma. Reworking of Paleoarchean, c. 3400-3250 Ma crust led to the formation of c. 3150 Ma granites now exposed within a narrow belt in the eastern Gawler Craton. Following this, there is no known record of significant tectonic activity until the onset of bimodal magmatism during the Neoarchean to earliest Paleoproterozoic, c. 2560-2470 Ma. This magmatism was terminated by high temperature metamorphism and deformation during the 2465- 2410 Ma Sleafordian Orogeny. Magmatic events associated with widespread sedimentation over the interval c. 2000-1740 Ma largely sources this older crust. The c. 1730-1690 Ma Kimban Orogeny reworked these Paleoproterozoic basins and the Neoarchean basement in a pre-dominantly transpressional orogenic system. Juvenile mantle input followed by widespread crustal melting occurred over the interval c. 1620- 1570 Ma. This period of intense magmatism initiated with emplacement of the relatively juvenile c. 1620- 1608 Ma St Peter Suite. This was followed by the economically significant c. 1600-1570 Ma Gawler Range Volcanics/Hiltaba Suite magmatic event, which resulted from widespread mid-crustal melting. Synchronous deformation and high temperature metamorphism accompanied the Gawler Range Volcanics/Hiltaba Suite magmatic event indicating it occurred in an orogenic environment. Far field stress was distributed around a central core zone of largely undisturbed Gawler Range Volcanics with deformation localised in the northern and southern Gawler Craton. The Gawler Range Volcanics/ Hiltaba Suite magmatic event resulted in formation of a province of major economic significance that includes the giant Olympic Dam Cu-Au-U ore body.
... In contrast to the first domain, the positive density and more magnetically susceptible bodies are offset with respect to one another. The northern boundary of the second domain is defined by the edge of S1 and appears to dip to the northwest cross-cutting the uplifts of the Ammaroodinna Ridge, and coincides with the Sarda Bluff Fault (SBF) a major boundary that has been interpreted on a crustal scale seismic reflection profile along B-B (Korsch et al., 2010). By contrast, the boundary between the Middle Bore Block and Ammaroodinna Block is defined by the boundary between S1 and D1 in the gravity inversions (Fig. 7). ...
... Similarly, a constant background value of 2670 kg/m 3 was assumed for the basement, so variations from this value should only be interpreted as density contrasts. In both forward models, a component of the decreasing regional gravity anomaly to the northwest is assumed to be caused by the increasing depth of the Moho towards the Musgrave Province as based on observations from seismic reflection profiles (Korsch et al., 1998(Korsch et al., , 2010Lambeck and Burgess, 1992) inferences from flexural backstripping of the Officer Basin (Haddad et al., 2001) and potential field modelling of the Musgrave Province (Aitken et al., 2009). This variation in Moho depth is inferred to be caused by flexure of a rigid lithosphere in response to loading along thrust faults that were active during uplift of the Musgrave Province in the Petermann and subsequent intracratonic orogenies (e.g. ...
... This profile is coincident with a crustal scale seismic reflection profile (Korsch et al., 2010;Stolz, 2010) and a lithospheric-scale magnetotelluric survey (Selway et al., 2010). The modelled profile is also coincident with shallow seismic reflection profiles 83-400 and 84-400, which were used to constrain the basin geometry (Fig. 11). ...
The Archaean to Mesoproterozoic basement of northern South Australia is almost completely overlain by thick Neoproterozoic and younger basins (≪1% outcrop), yet is likely to preserve an important record of the interactions between the Archean-Proterozoic Gawler Craton and the Proterozoic Musgrave Province during the amalgamation of Australia in the Proterozoic. However, constraints on the location and geometry of the boundary between these provinces are poor. We use potential field data to determine the 3D basement architecture and so constrain where this Palaeo-Mesoproterozoic boundary may be located beneath the Eastern Officer Basin. We establish the geometry and properties of the overlying basins and explicitly include them during forward and inverse modelling of potential field data to highlight the structure of the underlying basement. Our analysis identifies three crustal domains. (1) Southeast of the steep northeast-southwest Middle Bore Fault, positive gravity and magnetic anomalies are co-located and sourced from bodies in the upper crust, these bodies overlie middle to lower crust that is apparently uniform. (2) Between the Middle Bore Fault and the southern edge of the Munyarai Trough, the highest amplitude gravity and magnetic anomalies are not co-located and are sourced from large northwest dipping bodies. (3) To the northwest, the crust underlying the Munyarai Trough has similar properties to the Musgrave Province, suggesting that the Musgrave Province extends at least 50. km beneath the Eastern Officer Basin. Although details of the geology in the second (central) domain are poorly constrained, the domain preserves large crustal-scale Precambrian structures and is interpreted to mark the boundary between the Gawler Craton and the Musgrave Province. In particular, the multiply reactivated Middle Bore Fault forms a major crustal boundary and is interpreted to mark the northern limit of the Gawler Craton. The Middle Bore Fault may have formed as early as the Kimban Orogeny (~1.7 Ga), although substantial reactivation and modification of the crustal architecture could have occurred between the Kimban Orogeny and intrusion of the cross-cutting Gairdner Dolerite Dykes (827 Ma). © 2011 Elsevier B.V.
