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Representative zircon from sample R1708858 showing the location of analyses, annotated with their IMF-corrected 207 Pb/ 206 Pb ages. Transmitted light (left) and CL images (right). All analysis numbers are prefixed by 858.
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The glaciogenic nature of the Yudnamutana Subgroup was first recognized over a century ago, and its global significance was recognized shortly after, with the eventual postulation of a global Sturtian Glaciation and Snowball Earth theory. Much debate on the origin and timing of these rocks, locally and globally, has ensued in the years since. A sig...
This geochronological study was undertaken within the scope of the Mineral Systems Drilling Program (MSDP). This program aimed at improving the understanding of the geology and prospectivity of the southern Gawler Ranges margin area on the northern Eyre Peninsula stimulating exploration in this region. Archean-Palaeoproterozoic basement rocks, expo...
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... However, in comparison to the structural domain to the west of the Pickaxe Fault, the metamorphic grade in the domain between the Pickaxe and Iron Knob faults appears to have been significantly lower, probably greenschist to lower amphibolite facies, given the lack of recorded metamorphic zircon growth in dated samples with apparent Kimban-aged fabrics. (Fraser et al., 2010b;McAvaney and Jagodzinski, 2010). ...
Major lithospheric boundaries play a fundamental role in localizing crustal deformation and metal enrichment in the crust. Their identification in poorly exposed terranes remains challenging and typically relies on a combination of sparse outcrop and drill hole data extrapolated using regional gravity and magnetic datasets. The high
complexity in potential field data as well as the limited depth sensitivity to mostly upper to mid-crustal levels increases the ambiguity in identifying coherent lithospheric domains as well as the trans-lithospheric boundaries that cross into the subcontinental lithospheric mantle. Here we present a different approach using a combination of deep-probing magnetotelluric and seismic reflection methods, integrated with Nd isotope and inherited zircon ages of crustally-derived felsic igneous rocks, to locate and characterize a concealed Archean-Proterozoic lithospheric boundary within the Gawler Craton, South Australia. The boundary extends for approximately ∼600 km in the eastern part of the craton, from the supergiant iron oxide-copper-gold-uranium (IOCG-U) Olympic Dam deposit in the north to outcrops of the Kalinjala Shear Zone on southern Eyre Peninsula in the south. Using our approach we show a significant reduction in the uncertainty of the location of this boundary
between these two end-points. While a range of locations are permissible based on potential field data across northern Eyre Peninsula, our integrated approach points towards a precise location east of previous interpretations, beneath the upper crustal Roopena Fault.
... , 2 Reid and Jagodzinski (2011), 3 , 4 McAvaney and , 5 Reid and Jagodzinski (2012), 6 Reid et al. (2007), 7 Jagodzinski et al. (2007), 8 Fraser et al. (2007), 9 Fanning (1997), 10 Jagodzinski et al. (2006), 11 Budd (2006), 12 Reid (2007), 13 Teasdale (1997), 14 Finlay (1993), 15 Jagodzinski and McAvaney (2017), 16 Reid (2015), Hopper 17 (2001) and 18 Dawson (2016) et al. (1988), Fanning et al. (2007), Finlay (1993), , Fraser et al. (2007), Fraser et al. (2012), Hopper (2001), Howard et al. (2011a), Howard et al. (2011b), Jagodzinski and Reid (2010), Jagodzinski et al. (2006), Jagodzinski et al. (2007), Jagodzinski et al. (2012), Jagodzinski and McAvaney (2017), Lane (2011), Lane et al. (2015), McAvaney and Jagodzinski (2012), Mortimer et al. (1988), Payne et al. (2008), Reid and Jagodzinski (2011), Reid and Jagodzinski (2012), Reid (2007), Reid et al. (2007), Swain et al. (2005a), Teasdale (1997) (Middlemost, 1994). (b) Fe* vs SiO2 diagram (Frost, 2001). ...
... It comprises an elliptical magnetic pluton which can be traced on magnetic imagery spanning 9 x 2.5 km orientated in a north-south direction. The Deuter Diorite (Fig. 5b) is medium-to coarse-grained and composed of plagioclase and hornblende crystals in a groundmass of biotite, pyroxene, K-feldspar and minor quartz with trace titanite, magnetite, apatite and zircon (McAvaney and Jagodzinski, 2012). ...
... The Deuter Diorite is an intermediate pluton comprising granodiorite, diorite and gabbroic phases (McAvaney and Jagodzinski, 2012). The pluton is dominated by an equigranular medium-to coarse-grained diorite, quartz diorite to quartz-monzonite composed of plagioclase, hornblende, biotite and minor quartz ± clinopyroxene ± k-feldspar, with accessory magnetite, apatite and titanite. ...
During the period 1745–1700 Ma felsic and mafic rocks were intruded throughout the
Gawler Craton broadly coeval with the 1740–1690 Ma Kimban Orogeny. These rocks were
previously considered part of the Lincoln Complex, a stratigraphic term defined by
Thomson (1980) to describe the igneous rocks intruding the Archean to Paleoproterozoic
basement of the Eyre Peninsula during the later Paleoproterozoic. However, this term is
now in disuse due to the fact that more recent U-Pb geochronology has revealed that units
included within the Lincoln Complex range in age from the Mesoarchaean to the
Paleoproterozoic, and the term thus groups together units which are not genetically related.
The term Peter Pan Supersuite has been defined to describe those parts of the Lincoln
Complex which are synchronous with the Kimban Orogeny. The supersuite contains three
suites: the Moola Suite (1745–1735 Ma), the Pinbong Suite (1735–1700 Ma) and the Moody
Suite (1720–1700 Ma).
The Moola Suite is best exposed on north-eastern Eyre Peninsula, but also occurs in the
eastern Gawler Craton beneath the Stuart Shelf, the Peake and Denison Inliers and
Yoolperlunna Inlier in the northern Gawler Craton, and the Fowler Domain in the western
Gawler Craton. It contains unfoliated to weakly foliated mica-poor granites as well as
diorite, dolerite and amphibolite. Granites of the Moola Suite are classified as magnesian,
alkalic to calc-alkalic and metaluminous, and represent melts of heterogeneous crustal
source regions, demonstrated by broad Sm-Nd isotopic signatures (ƐNd(1740 Ma) = -17.1 to
-2.4). The mafic rocks of the Moola Suite consist of two geochemical groups: a tholeiitic and
LREE-depleted group and a calc-alkaline, LREE-enriched group. The depleted, tholeiitic
mafic rocks are characterised by low [La/Yb]N ratios (1.4–3.6) and juvenile Sm-Nd signatures
(ƐNd(1740 Ma) = -1.2 to 0.4). In contrast, the enriched, calc-alkaline mafic rocks are
characterised by high [La/Yb]N ratios (10.8–66.4) and evolved Sm-Nd signatures (ƐNd(1740 Ma) =
~-8.8).
The Pinbong Suite is the most widespread suite in the Peter Pan Supersuite, occurring on
central and southern Eyre Peninsula in the southern Gawler Craton, the Olympic Domain in
the eastern Gawler Craton, Coober Pedy Ridge in the northern Gawler Craton and in the
central Gawler Craton. It includes foliated to migmatitic biotite-rich granites, dolerites and
gabbros. Granitic rocks are mostly peraluminous or metaluminous and largely magnesian
and alkali-calcic, while the gabbroic rocks are metaluminous and enriched in alkalis.
Pinbong Suite granites have ƐNd(1730 Ma) values that range from -11.7 to -4.3. Two geochemical
groups are also observed in the Pinbong Suite gabbros: tholeiitic and LREE-depleted
([La/Yb]N = 3–8) and calc-akaline, LREE-enriched ([La/Yb]N = 12.9–36.2). Less distinction,
however, is observed in the Sm-Nd composition, with the tholeiitic and LREE-depleted
gabbros displaying slightly more evolved Nd signatures (ƐNd(1730 Ma) = -5.3 and -4.6) than the
calc-akaline, LREE-enriched gabbros (ƐNd(1730 Ma) = -3.8 and -3.4). Isotopic signatures of the
Pinbong Suite gabbros suggest an enriched mantle source region.
Comparable geochemical characteristics of the Moola Suite and the Pinbong Suite suggest
similar crustal and mantle source regions were melting during their genesis. Signatures for
the Moola and Pinbong Suite granites are consistent with granites generated in orogenic
settings from a lower- to mid-crustal c. 2565–2410 Ma Sleaford Complex or c. 3150 Ma
Cooyerdoo Granite source region. The geochemical characteristics of the mafic rocks of the
Peter Pan Supersuite are indicative of extensional-related melting events by lithospheric
extension or thinning. The mafic rocks represent a heterogeneous mantle source region that comprises an older, enriched lithospheric mantle reservoir, enriched in incompatible
elements and relatively depleted in compatible elements, and a younger, juvenile mantle.
The Moody Suite is restricted to the Tumby Bay area on central-eastern Eyre Peninsula, and
includes unfoliated leucogranite, monzogranite and monzonite which commonly contains
metasedimentary xenoliths derived from the Paleoproterozoic Hutchison Group country
rock. The Moody Suite intrusives are ferroan, calc-alkalic to alkali-calcic and peraluminous,
and has moderately evolved Sm-Nd isotopic signatures (ƐNd(1700 Ma) = -10.2 to -4.5),
consistent with derivation from the Hutchison Group. The geochemical signature of the
Moody Suite is typical of A-type post-orogenic granites derived from continental crust or
underplated crust that has been through a cycle of continent-continent collision.
... The Cooyerdoo Granite is in faulted contact at its eastern margin with the Myola Volcanics and Broadview Schist, a sequence of c. 1795 Ma felsic and mafic volcanics and shallow marine sandstones and siltstones Szpunar and Fraser 2010). The Spencer Domain was intruded by a suite of granitic and doleritic rocks at c. 1750-1745 Ma, including the Burkitt Granite Jagodzinski and McAvaney 2016;McAvaney and Jagodzinski 2012), and underwent low-temperature metamorphism and fabric development during the Kimban Orogeny (1730( -1690. The northsouth-trending Roopena Shear Zone also formed at this time (Fig. 1). ...
The stratigraphic term ‘Lincoln Complex’ was conceived to describe intrusive rocks associated with the Kimban Orogeny, originally thought to span the time period 1850–1690 Ma, and included the Donington Suite, Colbert Granite, Moody Suite, Wertigo Granite, Middle Camp Granite and Carappee Granite (Parker, 1993, Parker et al., 1985, Thomson, 1980). However, subsequent structural mapping and geochronology on southern Eyre Peninsula and Yorke Peninsula revealed that the Donington Suite and Colbert Granite were intruded and deformed as part of a separate tectonic and magmatic event at c.1850 Ma, the Cornian Orogeny (Reid et al., 2008a, Hoek & Schaefer, 1998). The Kimban Orogeny was redefined to extend from 1730–1690 Ma, separated from the Cornian Orogeny by a period of sedimentation and volcanism (Hand et al. 2007). More recent geochronology has revealed that the ‘Lincoln Complex’ also includes other units ranging from Archaean to Palaeoproterozoic in age which are also not related to the Kimban Orogeny, such as the Cooyerdoo Granite (c.3150 Ma), Coolanie Gneiss (c.2820 Ma), protoliths of the Minbrie Gneiss (2550–2440 Ma), the Carpa Granite (c.2515 Ma) and the Wertigo Granite (1790–1770 Ma) (Fraser & Neumann, 2010). The identification and characterisation of these distinct magmatic events is vital for understanding the geological evolution of the Gawler Craton.
This paper presents a stratigraphic definition of the Tip Top Granite, a previously unnamed felsic intrusive belonging the ‘Lincoln Complex’ (Weste, 1996), but identified by new geochronology to be temporally equivalent to the Wertigo Granite. It also presents new whole rock geochemistry and Nd isotope data on the Tip Top Granite and Wertigo Granite, characterises the melt source and tectonic setting of these units and discusses the broader significance of 1790–1770 Ma magmatism in the Gawler Craton.
... The basement geology of the Lake Gilles area (Fig. 4) comprises a Neoarchean (~2530 Ma) sequence of interlayered ortho-and paragneiss (Fraser and Neumann 2010;Reid et al. 2008) intruded by granite plutons and dolerite dykes and plugs during the Kimban Orogeny (1730- 1690 Ma), including the Burkitt Granite and unnamed diorite in DDH LED001 ( McAvaney et al. 2012). This is overlain by the Corunna Conglomerate, a package of alluvial and fluvial sediments deposited prior to the extrusion of the GRV (maximum depositional age ~1680 Ma; Fraser and Neumann 2010) and gently folded during the Kararan Orogeny ( Hand et al. 2008;Morgan 2007). ...
... The rhyolite contains granite xenoliths similar to the Burkitt Granite. Intrusions of the GRV are known to extend a substantial distance from the major outcrop area, including intersections in DDH LED001 (229988), where diorite is intruded by basalt, andesite and dacite which share geochemical affinities to the GRV ( McAvaney et al. 2012). Although not observed in outcrop, lag of coarse-grained and pegmatitic granite along the southern margin of the Gawler Ranges is likely to be derived from shallowly covered Hiltaba Suite granite. ...
Along the southern margin of the Mesoproterozoic (~1590 Ma) Gawler Range Volcanics, on northern Eyre Peninsula, numerous occurrences of silver, lead, zinc and copper mineralisation have been recorded at or near the base of the volcanics and within older metamorphosed rocks altered by hydrothermal fluids associated with the ~1590 Ma igneous event. In this investigation, rocks showing evidence of hydrothermal crystallisation or alteration, from sites near Lake Gilles and Roopena, were sampled and examined to assess the style of hydrothermal activity and associated mineralisation. The work contributes data on the extent and characteristics of hydrothermal activity that can be used to refine models, currently proposed, of an extensive Proterozoic subvolcanic epithermal mineral system across the region. The results will assist with ongoing assessment of the potential for formation and preservation of large or high-grade mineral deposits in the district.
Trace element geochemistry was determined for twenty samples that included hydrothermal granite breccia, fluid-brecciated metasediment with calcite/tourmaline/apatite or hematite/chlorite alteration, and epithermal vein quartz. Textural features of breccias and veins were described and interpreted. Alteration mineralogy was assessed using visible-shortwave infrared and thermal infra spectral analysis, and scanning electron microscopy. Accessory minerals containing copper, lead, bismuth, silver or zinc were identified with the aid of scanning electron microscopy and energy dispersive x-ray analysis.
Alteration mineralogy of tourmaline, calcite, apatite, sericite, chlorite and hematite in the fluid-brecciated metasediments in the Roopena area is interpreted as the result of mesothermal fluid activity developed around igneous intrusions and along major fractures. Quartz veins from the Lake Gilles area crystallised along with fluorite, barite, muscovite, feldspar, kaolinite, halloysite and smectite. Minor base metal sulphides and silver minerals were contained in quartz, but pyrite, alunite and dickite were not detected. Anomalous trace elements included Ag, Sb, Te, Bi Cu, Pb and Zn. The mineral assemblage and anomalous chemistry are consistent with low-sulfidation, epithermal vein systems forming within the the argillic alteration zone of an intrusion-related hydrothermal system. The presence of silver and copper chlorides, copper sulfate, lead oxide, jarosite and gypsum, along with some of the goethite, hematite and opaline silica are interpreted as due to later oxidation by near-surface weathering, under probable arid conditions.
Textures in vein quartz from the Lake Gilles area show lattice bladed calcite replaced by quartz, colloform banding, feathery and plumose quartz, all of which are indicative of boiling in hydrothermal systems. This equates to shallow crustal levels and environmental conditions favourable for the precipitation of precious metals. The preservation of the boiling zone in this ancient epithermal system, along with the presence of lead, zinc and copper minerals in epithermal quartz, provide encouragement that in addition to further precious metal deposits, base metal deposits are possible within the subepithermal portion of the system.
As part of the current mapping programme to produce a second edition of the PORT
AUGUSTA 250K map sheet, 8 samples from this map sheet and adjoining WHYALLA 250K
map sheet were dated by U-Pb zircon on SHRIMP IIe at Geoscience Australia during 2014
and 2016. These samples were selected in an attempt to solve two major uncertainties
about the stratigraphy on northern Eyre Peninsula: (i) the age range of the Hutchison
Group, which has yielded maximum depositional ages ranging from Neoarchaean to
Palaeoproterozoic, and (ii) the reclassification of the ‘Lincoln Complex’, a term originally
conceived to describe magmatism associated with the Kimban Orogeny, but now known to
comprise a grouping of unrelated rocks ranging from Neoarchaean to Palaeoproterozoic in
age.
Three samples were selected from Salt Creek, 30 km northeast of Cowell on the eastern
margin of the Cleve Domain. Here quartzite and calc-silicate of the Warrow Quartzite, a
formation within the Hutchison Group, are structurally interleaved with the Neoarchaean
Minbrie Gneiss. Szpunar et al. (2011) proposed three divisions of the Hutchison Group; the
‘Middleback group’, thought to contain a Neoarchaean sedimentary sequence, and the
‘Cleve group’ and ‘Darke Peak group’, thought to contain two distinct Palaeoproterozoic
sedimentary sequences. The proposed Archaean and Palaeoproterozoic divisions of the
Hutchison Group are separated by a belt of felsic igneous rocks which host major shear
zones formed during the Kimban Orogeny (1740–1690 Ma), The c. 2820 Ma Coolanie Gneiss,
the Neoarchaean Minbrie Gneiss and the Hutchison Group at Salt Creek occur within this
belt of rocks. The samples were dated from Salt Creek to test whether the Coolanie Gneiss
represents a major tectonic boundary between the Palaeoproterozoic and Neoarchaean
parts of the Hutchison Group. Sample 2014268, a quartz-feldspar-biotite migmatitic gneiss
of the Minbrie Gneiss, yielded a magmatic crystallisation age of 2422 ± 5 Ma, similar to other
known ages of the formation. Sample 2014264, from the Warrow Quartzite structurally
interleaved with the Minbrie Gneiss yielded a maximum depositional age of 2004 ± 10 Ma,
similar to other published ages of the Warrow Quartzite. No change in zircon provenance is
indicated by these results, suggesting that the Coolanie Gneiss does not delineate a major
structural boundary within the Hutchison Group. Sample 2014267 is a weakly foliated
granite which intrudes the Minbrie Gneiss. It contained only a few zircons, two of which
produced concordant analyses at c. 2445 Ma and 1740 Ma. The latter might indicate that the
granite was emplaced during the Kimban Orogeny, but based on only two grains, very little
of geological significance can be interpreted.
Five samples of various lithologies of the ‘Lincoln Complex’ from the Roopena area and
Cleve Hills were selected as part of a study to create a new stratigraphic nomenclature for
magmatism associated with the Kimban Orogeny, the Peter Pan Supersuite, and reclassify
those units within the ‘Lincoln Complex’ which predate the Kimban Orogeny and are
therefore not genetically associated with this event.
Sample 2017712, the Wortham Granite, is a pink medium-grained feldspar-quartz-biotitetourmaline
granite from the Roopena area ~40 km west of Port Augusta. The very low zircon
yield produced an upper intercept age 1747 ± 13 Ma. As with the weakly foliated granite
from Salt Creek (2014267), this granite was probably emplaced during the Kimban Orogeny.
Sample 2017715, the Tip Top Granite, is a pink medium-grained quartz-potassium feldsparplagioclase-
muscovite granite from the Roopena area. It yielded a magmatic age of
1773 ± 6 Ma with a dominant component of inherited zircon at 1853 ± 6 Ma, probably
derived from the Donington Suite, and shares strong similarities to the zircon age
spectrum of the Wertigo Granite.
Sample 2074175 is a porphyritic quartz-feldspar-biotite rock, interpreted to represent a
deformed volcanic sill intruding the Katunga Dolomite at Fern Quarry in the Cleve Hills.
It yielded a magmatic crystallisation age of 1720 ± 6 Ma, within uncertainty of many other
granites associated with the Kimban Orogeny in the Cleve Domain.
Sample 2074177 is a medium-grained equigranular quartz-potassium feldspar-plagioclasemuscovite
granite which intrudes the Warrow Quartzite as a sill at Poornamookinie Creek,
about three kilometres north of Cleve. It was found to contain only a small number of
zircons, two of which provide a maximum crystallisation age of c. 2010 Ma for the sill. With
such a low zircon yield, it is still possible that this is a Kimban-aged intrusion that did not
crystallise magmatic zircon, and the few zircons it contains inherited from the Warrow
Quartzite it intrudes.
Sample 2065418 is a quartz-muscovite metasediment interleaved with the c. 2820 Ma
Coolanie Gneiss in the Cleve Hills. It yielded a maximum depositional age of 2517 ± 11 Ma,
and is interpreted to be an equivalent to metasedimentary units of the Sleaford Complex
which has been structurally interleaved with the Coolanie Gneiss during the Kimban
Orogeny.
