Academic literature on the topic 'Hiltaba Suite'

The petrography and geochemistry of zircon offers an exciting opportunity to better understand the genesis of, as well as identify pathfinders for, large magmatic–hydrothermal ore systems. Electron probe microanalysis, laser ablation inductively coupled plasma mass spectrometry, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging, and energy-dispersive X-ray spectrometry STEM mapping/spot analysis were combined to characterize Proterozoic granitic zircon in the eastern Gawler Craton, South Australia. Granites from the ~1.85 Ga Donington Suite and ~1.6 Ga Hiltaba Suite were selected from locations that are either mineralized or not, with the same style of iron-oxide copper gold (IOCG) mineralization. Although Donington Suite granites are host to mineralization in several prospects, only Hiltaba Suite granites are considered “fertile” in that their emplacement at ~1.6 Ga is associated with generation of one of the best metal-endowed IOCG provinces on Earth. Crystal oscillatory zoning with respect to non-formula elements, notably Fe and Cl, are textural and chemical features preserved in zircon, with no evidence for U or Pb accumulation relating to amorphization effects. Bands with Fe and Ca show mottling with respect to chloro–hydroxy–zircon nanoprecipitates. Lattice defects occur along fractures crosscutting such nanoprecipitates indicating fluid infiltration post-mottling. Lattice stretching and screw dislocations leading to expansion of the zircon structure are the only nanoscale structures attributable to self-induced irradiation damage. These features increase in abundance in zircons from granites hosting IOCG mineralization, including from the world-class Olympic Dam Cu–U–Au–Ag deposit. The nano- to micron-scale features documented reflect interaction between magmatic zircon and corrosive Fe–Cl-bearing fluids in an initial metasomatic event that follows magmatic crystallization and immediately precedes deposition of IOCG mineralization. Quantification of α-decay damage that could relate zircon alteration to the first percolation point in zircon gives ~100 Ma, a time interval that cannot be reconciled with the 2–4 Ma period between magmatic crystallization and onset of hydrothermal fluid flow. Crystal oscillatory zoning and nanoprecipitate mottling in zircon intensify with proximity to mineralization and represent a potential pathfinder to locate fertile granites associated with Cu–Au mineralization.

Mesoproterozoic felsic magmatism of the Gawler Range Volcanics and Hiltaba Suite granites occurred at 1585–1595 Ma across much of the Gawler Craton, South Australia. Nd isotopic analysis of this felsic magmatism, combined with petrological and geochemical arguments, suggest derivation by partial melting of both Paleoproterozoic and Archean crust. The majority of samples analyzed have Nd isotopic and geochemical characteristics compatible with the involvement of Paleoproterozoic crust stabilized during the 1.85–1.71 Ga Kimban orogeny as sources for the Mesoproterozoic magmatism; others require derivation from sources dominated by Archean rocks. This cycle of Paleoproterozoic crustal stabilization followed by involvement of this crust Mesoproterozoic felsic magmatism is one previously documented from many parts of Mesoproterozoic Laurentia. On the basis of models proposing East Australia–Antarctica to be the conjugate landmass at the rifted margin of western North America, it appears that the voluminous magmatism of South Australia is another example of a typically Mesoproterozoic style of magmatism linked to Laurentia. This Mesoproterozoic magmatism appears temporally linked to regional high-temperature, low-pressure metamorphism of the region, and together with the presence of mantle-derived magmas, implicates the operation of large-scale tectono-thermal processes in the origin of felsic magmatism at 1590 Ma.

Abstract Extrusive and intrusive felsic magmas occur throughout the evolution of silicic-dominated large igneous province magmatism that is temporally related to numerous economically significant iron oxide copper-gold (IOCG) deposits in southern Australia. We investigate zircon trace element signatures of the felsic magmas to assess whether zircon composition can be related to fertility of the volcanic and intrusive suites within IOCG-hosted mineral provinces. Consistent with zircon forming in oxidizing magmatic conditions, the rare earth element (REE) patterns of zircon sourced from both extrusive and intrusive magmatic rocks are characterized by light REE depletions and a range of positive Ce and negative Eu anomalies. The timing of the major phase of IOCG mineralization overlaps with the early part of the first phase of Lower Gawler Range Volcanics magmatism (1593.6–1590.4 Ma) and older intrusive magmatism of the Hiltaba Suite (1593.06–1590.50 Ma). Zircon in these mineralization-related intrusives and extrusives is distinguished from zircon in younger, mineralization-absent rocks by higher Eu/Eu*, Ce/Ce*, and Ti values and separate magma evolution paths with respect to Hf. These zircon characteristics correspond to lower degrees of fractionation and/or crustal assimilation, more oxidizing magmatic conditions, and higher magmatic temperatures, respectively, in magmas coeval with mineralization. In this respect, we consider higher oxidation state, lower degrees of fractionation, and higher magmatic temperatures to be features of fertile magmas in southern Australian IOCG terrains. Similar zircon REE characteristics are shared between magmas associated with southern Australian IOCG and iron oxide-apatite (IOA) rhyolites from the St. Francois Mountains, Missouri, namely high Ce/Ce* and high Dy/Yb, indicative of oxidized and dry magmas, respectively. The dry and more fractionated nature of the IOCG- and IOA-associated magmas contrasts with the hydrous and unfractionated nature of fertile porphyry Cu deposit magmas. As indicated by high Ce/Ce* ratios, the oxidized nature is considered a key element in magma fertility in IOCG-IOA terrains. In both IOCG and IOA terrains, the trace element compositions of zircon are able to broadly differentiate fertile from nonfertile magmatic rocks.

The Tarcoola Goldfield, central South Australia, is one of a number within the Central Gawler Gold Province (CGGP) spatially related to Hiltaba Suite granites. This study investigates the origin of mineralisation at Tarcoola, and the petrogenesis of granites at and around Tarcoola. ‘Hiltaba Suite’ granites in the Tarcoola region are assigned to two supersuites, which is expanded to four once granites from the rest of the Gawler Craton are considered. The term Hiltaba Association Granites (HAG) is introduced as the parental unit of the Jenners, Malbooma, Venus and Roxby Supersuites. These criteria are applied to the felsic parts of the comagmatic Gawler Range Volcanics (GRV). The HAG and GRV are grouped as the bimodal Gawler Ranges–Hiltaba Volcano–Plutonic (GRHVP) Association. The felsic components generally have high K, HFSE, LIL, are fractionated and evolved, have moderate to high Fe/Mg, are slightly alkaline, metaluminous to slightly peraluminous, slightly oxidised and high-temperature. The supersuites of the Tarcoola region are the Malbooma Supersuite, which is more strongly evolved and fractionated than the Jenners Supersuite. Both Supersuites are I-type and evolved from a granodiorite composition by fractional crystallisation. The Pegler and Ambrosia Granites (Jenners Supersuite), and are dated at 1591.7 ± 5.8 and 1575.4 ± 7.8 Ma. The Big Tank, Kychering and Partridge Granites (Malbooma Supersuite), and are dated at 1589.9 ± 7.4, 1574.7 ± 4.3 and 1577 ± 8.5 Ma. The Roxby and Venus Supersuites are A-type granites and volcanics, with higher HFSE, F, and zircon saturation temperatures than the I-types. Nd-isotope data indicate that the felsic GRHVP formed by mixing between evolved mantle and crust. Narrow dykes of the high-K Lady Jane Diorite intrude the Tarcoola Goldfield. This unit, and other basalts of the GRHVP, are interpreted to represent mixing between evolved lithospheric and primitive asthenospheric mantle melts. The Paxton Granite at the Tarcoola Goldfield was dated as older than the HAG at ~1720 Ma. The Tarcoola Formation was deposited in an ensialic basin directly onto the Paxton, with the basal Peela Conglomerate Member contains zircons of 1732.8 ± 5.1 Ma and 1714.6 ± 7.9 Ma, and the middle parts of the Tarcoola Formation being deposited at 1656 ± 7 Ma. Mineralisation at the Tarcoola Goldfield is quartz-vein hosted within the Tarcoola Formation, and comprises Au±Pb-Zn. The veins are structurally-controlled. 40Ar/39Ar geochronology and field relationships show that brittle veining, mineralisation, alteration and intrusion of the Lady Jane Diorite, occurred synchronously at ~1580 Ma. A Pb-Pb isotope study at the Tarcoola Goldfield is consistent with sourcing of Pb from the Paxton Granite, but does not exclude a mixed source. A shift in Nd during alteration may show an input from the relatively primitive Lady Jane Diorite. An atlas shows correlations between the four supersuites and the two defined mineral provinces of the Gawler Craton. Notably the Roxby Supersuite is associated nearly exclusive with iron-oxide copper-gold mineralisation in the Olympic Cu-Au Province in the eastern part of the Craton. The I-type Jenners and Malbooma Supersuites are mostly restricted to the CGGP. A position inboard of a subduction zone (hot continental back-arc) rather than anorogenic setting is proposed.

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The ca. 1600–1580 Ma time slice is recognised as a significant period of magmatism and deformation throughout eastern Proterozoic Australia. Within the northern Yorke Peninsula, this period was associated with the emplacement of multiple phases of the Tickera Granite; an intensely foliated orange granite, a white leucogranite and a red granite. These granites belong to the broader Hiltaba Suite that was emplaced at shallow crustal levels, throughout the Gawler Craton. Geochemical and isotopic analysis suggests these granite phases were derived from a heterogeneous source region. The orange and red granites were derived from the Donington Suite and/or the Wallaroo Group metasediments with slight contamination from an Archean basement. The white leucogranite is sourced from a similar but slightly more mafic/lower crustal source. Phases of the Tickera Granite were emplaced synchronously with deformation that resulted in development of a prominent northeast trending structural grain throughout the Yorke Peninsula region. This fabric is a composite of two fold generations; early isoclinal folds that were refolded by later open upright folds. Isoclinal folding may have occurred during the ca. 1730–1690 Ma Kimban Orogeny, or just prior to emplacement of the Tickera Granite at ca. 1597–1577 Ma. The upright fold generation was contemporaneous with the emplacement of the Tickera Granite. The Yorke Peninsula shares a common geological history with the Curnamona Province, which was deformed during the ca. 1600–1585 Ma Olarian Orogeny, and resulted in development of early isoclinal (recumbent) folds overprinted by an upright fold generation, a dominant northeast–trending structural grain and spatially and temporally related intrusions. This suggests an apparent correlation with the geological history of the Curnamona Province, and that the Olarian Orogeny may have also affected the southeastern Gawler Craton. Constraint on the timing of the earlier isoclinal fold generation in the Yorke Peninsula will allow further understanding of the similarities between the two regions.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2016

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The Cairn Hill Fe-(Cu-Au) deposit is located within the World-class 1.6 Ga Olympic iron oxide-copper-gold (IOCG) Province of the Gawler Craton, South Australia. Cairn Hill deposit formation was penecontemperaneous with regional orogenesis, and is interpreted as a deep-level, ‘magnetite-rich’ end-member IOCG system hosted by an upper-amphibolite quartzofeldspathic ortho-gneiss and Mesoproterozoic (1600 – 1575 Ma) Hiltaba-equivalent Balta-suite granites and granodiorites. U-Pb zircon SHRIMP dating of a representative host rock and cross-cutting foliated granitic dyke, constrains the timing of mineralisation between ~1587 Ma and ~1525 Ma, respectively; suggesting an affinity to Hiltaba-age granitoids. The deposit strikes E-W over a distance of 1.3 km and is up to 40 m wide. It is characterized by two mineralised zones: the North- and South- Lodes, coincident with subsidiary structures within the transpressional Cairn Hill Shear Zone (CHSZ), and concordant with the strike of the encompassing magnetic anomaly. Progressive exhumation resulted in temperature and pressure decreases under high-fluid pressure causing the CHSZ to cross the brittle-ductile transition. This occurred relatively late in the hydrothermal-metamorphic evolution, resulting in a contractional duplex in a restraining bend suggestive of a positive flower structure providing an optimal conduit for hydrothermal fluid-flow. Early Na-Ca alteration has affected the host rocks predominantly characterised by albite + scapolite + diopside ± actinolite/titanite. Extensive K-Fe metasomatism has affected the host rocks overprinted by localised zones of intense, texturally-destructive high-temperature magnetite-biotite alteration that is typical of a transitional-style IOCG system. Associated hypogene iron mineralisation predominantly consists of magnetite, with extensive zones of a superimposed texturally-complex sulphide assemblage (pyrite-pyrrhotite-chalcopyrite). Definition of the IOCG deposit clan remains a contentious issue, primarily due to mis-classification and poor understanding of some individual deposits. Nevertheless, the general consensus is that IOCG deposits sensu-stricto represent a spectrum between high-temperature, deeper magnetite-rich end-member systems, such as Cairn Hill, and lower-temperature, shallower hematite-rich end-members.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2014

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Mesoproterozoic magmatism of the Gawler Craton and the Curnamona Province demonstrates regions of variable mantle input characteristics. Zircons from Hiltaba Suite granitoids and Gawler Range Volcanics, Gawler Craton, return εHf(T) values ranging from +7.1 to -0.4, +2.0 to -7.4, and +0.2 to -5.3 from the western, central, and eastern Gawler Craton respectively. Ninnerie Supersuite granitoids and Benagerie Volcanic Suite, Curnamona Province, return εHf(T) values ranging from +2.5 to -3.8. Mantle input modelling of the central/eastern Gawler Craton and the Curnamona Province returns similar mantle input fraction values ranging from 0.1 to 0.6, averaging 0.3, and 0.1 to 0.6, averaging 0.3, respectively. Hiltaba Suite magmatism of the western Gawler Craton is compositionally more juvenile than the central and eastern regions. The western Gawler Craton mantle input fractions range from 0.2 to 0.9 averaging 0.5, more elevated than the central/eastern regions of the Gawler Craton and the Curnamona province. The Benagerie Ridge region of the Curnamona Province displays similar bimodal ca. 1590 Ma magmatism, εHf(T) values, mantle input characteristics, crustal preservation (exhumation) and regional iron oxide copper-gold alteration as the highly prospective Olympic IOCG Province, Gawler Craton.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2014