A composite C-isotope profile for the Neoproterozoic Dalradian Supergroup of Scotland and Ireland

Prave, Anthony R.; Fallick, Anthony E.; Thomas, Ciby; Graham, Colin M.

doi:10.1144/0016-76492008-131

Cited by 110 publications

(110 citation statements)

References 65 publications

(59 reference statements)

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“…This study uses the global Neoproterozoic S-isotope record in conjunction with these age correlations to estimate d 34 S values in sulphur-poor stratigraphy. Prave et al (2009) (Halverson et al 2005(Halverson et al , 2007a and correlated observed excursions with key Neoproterozoic events. The metamorphic fluids affecting Dalradian carbonates during Grampian Event orogenesis are known to be carbon-poor; therefore, the isotopic composition of carbonate units is buffered (Holness & Graham 1995;Graham et al 1997;Thomas 2000) and carbonate d Halverson et al 2007b) and the Port Askaig Tillite at the base of the Argyll Group is interpreted to represent the Sturtian glacial episodes (Fig.…”

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confidence: 64%

“…2; Thomas et al 2004;Prave et al 2009;Rooney et al 2011). The base of the Dalradian sequence is dated at a maximum age of c. 800 Ma by the presence of Knoydartian deformation in the basement rocks, combined with no evidence of pre-Caledonian mineral ages in the Dalradian Supergroup (Noble et al 1996).…”

Section: Chronostratigraphic and Biostratigraphic Constraintsmentioning

confidence: 99%

“…The Neoproterozoic Era is recognized as a crucial time in Earth history, incorporating two snowball Earth events (Hoffman et al 1998) coupled with large fluctuations in seawater C-, O-, Sr-and S-isotope ratios (Halverson et al 2010). The increasing understanding of Neoproterozoic events and global isotope variations (Halverson et al 2010;Halverson & Shields-Zhou 2011) within the evolving Earth has impacted on the understanding of the Dalradian sequence and is beginning to refine the possible chronostratigraphies, particularly through the use of stable isotope stratigraphy (Thomas et al 2004;Prave et al 2009;Moles et al 2014).…”

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confidence: 99%

“…Gravity anomaly after Hussein & Hipkin (1981) and interpretation in Pattrick et al (1988). should be noted that correlation of the Ballachulish Limestone with the Bitter Springs anomaly would make the formations below too old if it is accepted that the base of the Dalradian is ,800 Ma. Prave et al (2009) (Noble et al 1996).…”

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confidence: 99%

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How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

Hill

Jenkin

Boyce

et al. 2013

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The genesis of quartz vein-hosted gold mineralization in the Neoproterozoic-early Palaeozoic Dalradian Supergroup of Scotland remains controversial. An extensive new dataset of S-isotope analyses from the Tyndrum area, together with correlation of the global Neoproterozoic sedimentary S-isotope dataset to the Dalradian stratigraphy, demonstrates a mixed sedimentary and magmatic sulphur source for the mineralization. d34 S values for early molybdenite-and later gold-bearing mineralization range from 22 to +12‰, but show distinct populations related to mineralization type. Modelling of the relative input of magmatic and sedimentary sulphur into gold-bearing quartz veins with d 34 S values of +12‰ indicates a maximum of 68% magmatic sulphur, and that S-rich, SEDEX-bearing, Easdale Subgroup metasedimentary rocks lying stratigraphically above the host rocks represent the only viable source of sedimentary sulphur in the Dalradian Supergroup. Consequently, the immediate host rocks were not a major source of sulphur to the mineralization, consistent with their low bulk sulphur and lack of metal enrichment. Recent structural models of the Tyndrum area suggest that Easdale Subgroup metasedimentary rocks, enriched in 34 S, sulphur and metals, are repeated at depth owing to folding, and it is suggested that these are the most likely source of sedimentary sulphur, and possibly metals, for the ore fluids.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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confidence: 64%

Section: Chronostratigraphic and Biostratigraphic Constraintsmentioning

confidence: 99%

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confidence: 99%

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How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

Hill

Jenkin

Boyce

et al. 2013

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“…The glaciogenic Port Askaig Formation of the Dalradian Supergroup, Scotland, was deposited on the northeast margin of Laurentia and has been correlated with the Sturtian glaciation using lithostratigraphic and chemostratigraphic techniques (38,39). A Re-Os age of 659.6 ± 9.6 Mya for the Ballachulish Slate near Loch Leven (40) has been cited as a maximum age constraint for the Port Askaig Formation; however, the Port Askaig is not present in the region, and the relationship of the date to glacigenic strata relies on regional correlations.…”

Section: Duration and Synchronicity Of The Sturtian Glacial Epochmentioning

confidence: 99%

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Rooney

Macdonald

Strauss

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

230

158

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After nearly a billion years with no evidence for glaciation, ice advanced to equatorial latitudes at least twice between 717 and 635 Mya. Although the initiation mechanism of these Neoproterozoic Snowball Earth events has remained a mystery, the broad synchronicity of rifting of the supercontinent Rodinia, the emplacement of large igneous provinces at low latitude, and the onset of the Sturtian glaciation has suggested a tectonic forcing. We present unique Re-Os geochronology and high-resolution Os and Sr isotope profiles bracketing Sturtian-age glacial deposits of the Rapitan Group in northwest Canada. Coupled with existing U-Pb dates, the postglacial Re-Os date of 662.4 ± 3.9 Mya represents direct geochronological constraints for both the onset and demise of a Cryogenian glaciation from the same continental margin and suggests a 55-My duration of the Sturtian glacial epoch. The Os and Sr isotope data allow us to assess the relative weathering input of old radiogenic crust and more juvenile, mantle-derived substrate. The preglacial isotopic signals are consistent with an enhanced contribution of juvenile material to the oceans and glacial initiation through enhanced global weatherability. In contrast, postglacial strata feature radiogenic Os and Sr isotope compositions indicative of extensive glacial scouring of the continents and intense silicate weathering in a post-Snowball Earth hothouse.rhenium-osmium geochronology | strontium isotopes | osmium isotopes | Windermere Supergroup | Neoproterozoic glaciation T he Snowball Earth hypothesis predicts that Neoproterozoic glaciations were global and synchronous at low latitudes and that deglaciation occurred as a result of the buildup of pCO 2 to extreme levels resulting in a "greenhouse" aftermath (1, 2). The temporal framework of Cryogenian glaciations is built on chemostratigraphy and correlation of lithologically distinct units, such as glaciogenic deposits, iron formation, and cap carbonates (3), tied to the few successions that contain volcanic rocks dated using U-Pb zircon geochronology (4). In strata lacking horizons suitable for U-Pb geochronology, Re-Os geochronology can provide depositional ages on organic-rich sedimentary rocks bracketing glaciogenic strata (5, 6). Moreover, Os isotope stratigraphy can be used as a proxy to test for supergreenhouse weathering during deglaciation (7). In a Snowball Earth scenario, we can make specific predictions for Cryogenian weathering: CO 2 consumption via silicate weathering should increase before glaciation, stagnate during the glaciation, and increase again during deglaciation. However, the use of a single weathering proxy to provide evidence for such a scenario, such as Sr isotopes from marine carbonates, is limited both by lithological constraints and an inability to distinguish between the amount of weathering and the composition of what is being weathered (8). The short residence time of Os in the present-day oceans (<10 ky) (9) provides a complementary higher resolution archive to Sr isotopes, and thus, insi...

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Middle Neoproterozoic (<750 Ma) to Early Ordovician Sedimentation along the Laurentian Margin of Iapetus

Strachan

Prave

Holdsworth

2012

Geological History of Britain and Ireland

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A composite C-isotope profile for the Neoproterozoic Dalradian Supergroup of Scotland and Ireland

Cited by 110 publications

References 65 publications

How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Middle Neoproterozoic (<750 Ma) to Early Ordovician Sedimentation along the Laurentian Margin of Iapetus

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