Geochemistry and tectonic settings of meta‐igneous rocks in the Arthur Lineament and surrounding area, northwest Tasmania*

Holm, OH; Crawford, AJ; Berry, Ron F.

doi:10.1111/j.1400-0952.2003.01033.x

Cited by 21 publications

(15 citation statements)

References 38 publications

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“…The diagenetic pyrite from three carbonaceous shale units, which are known not be associated with gold mineralization, were studied to compare with the diagenetic pyrite in carbonaceous shales that host the known deposits of Sukhoi Log, northern Carlin Trend, and Bendigo. The background or "barren" carbonaceous shales were selected from three districts: (1) the Paleoproterozoic Barney Creek Formation in the McArthur basin, northern Australia (Bull, 1998), which is the host to stratiform Zn-Pb-Ag mineralization (Large et al, 2005) but not known to host gold mineralization; (2) the Cambrian Alum Shale, Sweden, which is a strongly carbonaceous shale known to host low-grade U-Mo-Ni mineralization but not Au (Leventhal, 1991); and (3) the Mesoproterozoic Rocky Cape Group from the Longback area, western Tasmania (Holm et al, 2003), where carbonaceous shales carry significant diagenetic pyrite but with no known gold occurrences.…”

Section: Do All Carbonaceous Shales Contain Syngenetic Gold?mentioning

confidence: 99%

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

Large¹,

Bull²,

2011

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This paper presents evidence and arguments that carbonaceous sedimentary rocks were a source for Au and As in sediment-hosted orogenic and Carlin-type gold deposits and develops a corresponding genetic model. In this two-stage basin-scale model, gold and arsenic are introduced early into black shale and turbidite basins during sedimentation and diagenesis (stage 1) and concentrated to ore grades by later hydrothermal, structural, or magmatic processes (stage 2). In reduced continental margin basin settings, organic matter, sedimented under anoxic to euxinic conditions, immobilizes and concentrates gold, arsenic, and a range of trace elements (particularly V, Ni, Se, Ag, Zn, Mo, Cu, U) present in marine bottom waters, into fine-grained black mudstone and siltstone of slope and basin facies. During early diagenesis, gold and certain other trace elements (Ni, Se, Te, Ag, Mo, Cu, ±PGE) are preferentially partitioned into arsenian pyrite that grows in the muds. These processes produce regionally extensive black shale and turbidite sequences enriched in syngenetic gold and arsenic, commonly from 5 to 100 ppb Au and 10 to 200 ppm As. Rare organic-and sulfide-rich metalliferous black shales may contain up to 1 to 2 ppm Au and over 1,000 ppm As, present as refractory gold in arsenian pyrite and nanoparticles of free gold. During late diagenesis and early metamorphism (stage 2) the diagenetic arsenian pyrite is recrystallized to form coarser grained pyrite generations, and the organic matter is cooked to bitumen. Under higher grade metamorphism (lower greenschist facies and above) arsenian pyrite in carbonaceous shales is converted to pyrrhotite. These processes release gold, arsenic, sulfur and other elements (Sb, Te, Cu, Zn, Mo, Bi, Tl, and Pb) from the source rocks to become concentrated by hydrothermal processes, locally to produce gold ores, in structural sites such as fold hinge zones, shear or breccia zones within or above the black shale sequence. LA-ICP-MS analyses of diagenetic pyrite in carbonaceous sediments, both associated and not associated with gold deposits, suggests that invisible gold contents of greater than 250 ppb in diagenetic pyrite, are indicative of carbonaceous shale source rocks with the potential to produce economic gold deposits. Application of this sedimentary source-rock model enables a systematic exploration approach for sediment-hosted gold deposits, based on the distribution, composition and structure of carbonaceous shale sequences and their contained diagenetic pyrite.

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Section: Do All Carbonaceous Shales Contain Syngenetic Gold?mentioning

confidence: 99%

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

Large¹,

Bull²,

2011

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“…(Saccani, 2015). Data compiled from the literature: Delamerian orogen in mainland Australia after Crawford et al (1997) and Gibson et al (2015); Delamerian orogen in Tasmania after Holm et al (2003) and Meffre et al (2004); Thomson orogen after Fergusson et al (2009); and southern Victoria land after Cook (2007) and Cooper et al (2011).…”

Section: Discussionmentioning

confidence: 99%

Ediacaran mafic magmatism recorded in Cambrian eclogites of the Ross orogen, Antarctica: Implications for the Neoproterozoic rifting episodes along the Pacific‐Gondwana margin

Kim

Cheong

et al. 2022

Terra Nova

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We report the first finding of Ediacaran mafic magmatism in northern Victoria Land of the Ross orogen, Antarctica, based on ca. 600-590 Ma magmatic zircon cores in Cambrian eclogites. The mafic magmatism could be either linked to ca. 615-590 Ma incipient convergent margin magmatism in central segment of the Ross orogen, or ca. 600-580 Ma continental rift-related volcanism widespread in eastern Australia. The latter is preferred based on the trace-element compositions distinctive from those of arc-related basalts and the depleted mantle-like Hf isotopic compositions of zircon.Our results suggest dual rifting episodes during both the Ediacaran and Cryogenian (ca. 670-650 Ma) in the East Antarctic margin, correlative with those in eastern Australia. A spatial distribution of coeval rifting and subduction along the Ediacaran margin of East Antarctica is readily accounted for by rift inheritance; the upper-and lower-plate geometry resulting from detachment and transform faulting.

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“…There are major differences between Neoproterozoic sedimentation in the Adelaide Fold Belt, South Australia and the equivalent age stratigraphy in Tasmania, the Grassy Group on King Island and the Ahrberg and Togari Groups in northwest Tasmania (Calver & Walter 2000;Preiss 2000;Holm et al 2003). Intermixed with the Neoproterozoic rift sediments on King Island and in northwest Tasmania are large volumes of rift-related basalts, unseen in the Adelaide Fold Belt.…”

Section: Regional Significancementioning

confidence: 94%

“…In southeast Australia, the only igneous event of similar age is a 780 Ma rhyolite below the base of the Burra Group, in the Adelaide Fold Belt (Preiss 2000). Li (2001) andHolm et al (2003) argued that this rhyolite and the Cape Wickham granite are both related to rifting during early stages of the breakup of Rodinia. This is also consistent with the evidence from northwest Tasmania of a low-angle unconformity at the base of the Togari Group (?740 Ma: Calver & Walter 2000).…”

Section: Regional Significancementioning

confidence: 97%

Chemical U – Th – Pb monazite dating and the Proterozoic history of King Island, southeast Australia*

Berry

Holm

Steele

2005

Australian Journal of Earth Sciences

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The Proterozoic stratigraphy of Tasmania has some common aspects with South Australia but the Wickham Orogeny (760 Ma) has been a major contrasting feature.We have used chemical U-Th-Pb monazite dating to clarify the age relationships Monazites are typically concordant, with the measured common Pb component much less than the analytical error in electron probe micro -analysis (EPMA) (Cocherie et al. 1998, Scherrer et al. 2000. In-situ analysis and the high spatial resolution of EPMA allows the correlation of monazite age with the structural environment of the monazite grains and this is a major advantage in dating of metamorphic events (Williams & Jercinovic 2002). Finally, monazite has a high closure temperature so that in medium grade metamorphic rocks the grains close as they grow and resetting is controlled by recrystallisation: driven by strain, partial melting or hydrothermal activity (Cocherie et al. 1998, Seydoux-Guillame et al. 2002. For these reasons in -situ chemical dating of monazite by EPMA is revolutionising the dating of low to medium grade, regional metamorphic rocks. The major disadvantage of EPMA chemical age dating is that the high detection limits on Pb (~100 ppm) restrict the application to older events and/or high-Th monazite grains. Quantitative analyses of monazite grains were obtained using a Cameca SX50 electron probe microanalyser operat ed at 20kV and 100nA. The errors quoted in this work were estimated from counting statistics. The counting errors have been propagated through the age calculation using the rules for normally distributed er rors (e.g. Barford 1985). They do not include any systematic errors associated with calibration, or the errors in decay constants. The EPMA calibration was checked regularly using a monazite from the Wilson Lake Terrane, Canada (Thermal ionisation mass spectrometry (TIMS) age of 1000 2 (95% confidence) Ma; G. A. Jenner, pers. comm.) and reproduces the TIMS age to within error. Based on this result, we estimate that the systematic error is less than 1%. Weighted means and probability plots were calculated using ISOPLOT v2.49 (Ludwig 2001). For individual spot analyses, the 1 error is quoted in the tables. All other ages are given with errors shown at the 95% confidence level.King Island, located to the northwest of Tasmania, is composed of several different (meta-) sedimentary and igneous sequences (Fig. 2 ). The western half of the island is

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Geochemistry and tectonic settings of meta‐igneous rocks in the Arthur Lineament and surrounding area, northwest Tasmania*

Cited by 21 publications

References 38 publications

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits

Ediacaran mafic magmatism recorded in Cambrian eclogites of the Ross orogen, Antarctica: Implications for the Neoproterozoic rifting episodes along the Pacific‐Gondwana margin

Chemical U – Th – Pb monazite dating and the Proterozoic history of King Island, southeast Australia*

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