Surficial geochemical and mineralogical signatures of Ni-Cu-PGE deposits in glaciated terrain: examples from the South Range of the Sudbury Igneous Complex, Ontario, Canada

2021 ◽  
pp. 104301
Author(s):  
Sarah Hashmi ◽  
Matthew I. Leybourne ◽  
Daniel Layton-Matthews ◽  
Stewart Hamilton ◽  
M. Beth McClenaghan ◽  
...  
Keyword(s):  
The South ◽  
Igneous Complex ◽  
Sudbury Igneous Complex

scholarly journals Suitability of surficial media for Ni-Cu-PGE exploration in an established mining camp: a case study from the South Range of the Sudbury Igneous Complex, Canada

2021 ◽  
pp. geochem2021-051
Author(s):  
Sarah Hashmi ◽  
Matthew I. Leybourne ◽  
Stewart Hamilton ◽  
Daniel Layton-Matthews ◽  
M. Beth McClenaghan
Keyword(s):  
Anthropogenic Contamination ◽  
The South ◽  
Aqua Regia ◽  
Content Type ◽  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
Geochemical Study ◽  
Pge Mineralization ◽  
Supplementary Material

A geochemical study over the southwestern part of the South Range of the Sudbury Igneous Complex (SIC) was completed to assess the suitability of surficial media (humus, B-horizon soil and C-horizon soil) for delineating geochemical anomalies associated with Ni-Cu-PGE mineralization. Another objective was to test whether Na pyrophosphate can eliminate the effects of anthropogenic contamination in humus. Results of this study suggest that the natural geochemical signature of humus is strongly overprinted by anthropogenic contamination. Despite no indication of underlying or nearby mineralization, metal concentrations in humus samples by aqua regia collected downwind from smelting operations are higher compared to background, including up to 13 times higher for Pt, 12 times higher for Cu and 9 times higher for Ni. The high anthropogenic background masks the geogenic signal such that it is only apparent in humus samples collected in the vicinity of known Ni-Cu-PGE deposits. Results of this study also demonstrate that anthropogenically-derived atmospheric fallout also influences the upper B-horizon soil; however, lower B-horizon soil (at > 20 cm depth) and C-horizon soil (both developed in till) are not affected. Glacial dispersal from Ni-Cu-PGE mineralization is apparent in C-horizon till samples analyzed in this study. Compared to the background concentrations, the unaffected C-horizon till samples collected immediately down-ice of the low-sulfide, high precious metal (LSHPM) Vermilion Cu-Ni-PGE deposit are enriched over 20 times in Pt (203 ppb), Au (81 ppm) and Cu (963 ppm), and over 30 times in Ni (1283 ppm).Supplementary material:https://doi.org/10.6084/m9.figshare.c.5691080

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

A trishear model for the deformation of the Sudbury Igneous Complex, Canada

2017 ◽  
Vol 97 ◽  
pp. 212-224 ◽  
Author(s):  
Iris Lenauer ◽  
Ulrich Riller
Keyword(s):  
Igneous Complex ◽  
Sudbury Igneous Complex

The geochronology of uraniferous minerals in the Witwatersrand Triad; an interpretation of new and existing U-Pb age data on rocks and minerals from the Dominion Reef, Witwatersrand and Ventersdorp Supergroups

1977 ◽  
Vol 286 (1336) ◽  
pp. 567-583 ◽  
Keyword(s):  
Thermal Effects ◽  
Free State ◽  
The South ◽  
Witwatersrand Basin ◽  
Simple Interpretation ◽  
Igneous Complex ◽  
Radiogenic Lead ◽  
Sedimentary Sequences ◽  
Age Patterns ◽  
Bushveld Igneous Complex

Uranium and lead analyses of rock samples from the Witwatersrand, Ventersdorp, and Transvaal supergroups give mainly discordant ages. Samples from the Upper Witwatersrand of the Orange Free State give 207 Pb/ 206 Pb ages of ca. 3000 Ma. These data when considered together with earlier total conglomerate U -Pb analyses from the Dominion Reef Supergroup lead to the conclusion that the uraniferous minerals of the Dominion Reef, Witwatersrand, Ventersdorp and Transvaal conglomerates are 3050 ± 50 Ma old. In the northern parts of the Witwatersrand Basin the parent uraniferous minerals experienced a major reworking at 2040 ± 100 Ma which brought about the partial or complete resetting of the original 3050 Ma age. Radiogenic lead released during this reworking crystallized as galena in veins and fissures which cut across the uraniferous conglomerate horizons. This reworking appears to have had little effect in the Orange Free State to the south. Its age and geographical extent suggest it was caused by thermal effects which accompanied the emplacement of the Bushveld Igneous Complex at 1950 ± 150 Ma. Samples from the south, which were relatively unaffected by the ca. 2040 Ma reworking generally show the effects of recent uranium loss. In the northern part of the basin discordant age patterns characteristic of lead loss have been imposed on uranium-lead systems which were generally reset (partially or completely) by the ca. 2040 Ma event. The presence of 3050 Ma old minerals in sedimentary sequences which are probably younger than ca. 2740 Ma suggests the simple interpretation that the uraniferous minerals are predominantly detrital.

scholarly journals New hornblende and muscovite 40Ar/39Ar cooling ages in the central Rinkian fold belt, West Greenland

2006 ◽  
Vol 11 ◽  
pp. 115-124 ◽  
Author(s):  
Ann-Sofie Sidgren ◽  
Laurence Page ◽  
Adam A. Garde
Keyword(s):  
Metamorphic Grade ◽  
Fold Belt ◽  
The South ◽  
Igneous Complex ◽  
West Greenland ◽  
Structural History

The Palaeoproterozoic Rinkian fold belt in West Greenland consists of reworked Archaean basement, mainly orthogneiss, and the unconformably overlying Palaeoproterozoic Karrat Group. Both parts were intensely deformed and metamorphosed at around 1.87 Ga, at which time the crustal anatectic Prøven igneous complex was emplaced into the northern part of the belt. Seven new hornblende and muscovite 40Ar/39Ar cooling ages are presented from the central–northern parts of the Rinkian fold belt. Four 40Ar/39Ar hornblende ages ranging from 1795 ± 3 to 1782 ± 3 Ma were obtained from amphibolite and hornblendite enclaves in the Archaean orthogneiss, and two from relict dyke fragments in the latter that may be of Palaeoproterozoic age. Three 40Ar/39Ar muscovite ages of 1681 ± 6 Ma, 1686 ± 3 Ma and 1676 ± 3 Ma were obtained from samples of Karrat Group metagreywacke, andalusite schist and metasiltstone. The new 40Ar/39Ar ages, from hornblende and muscovite respectively, are very uniform and probably unrelated to local metamorphic grade and structural history, and are interpreted as regional late orogenic cooling ages. The new hornblende ages are significantly older than those previously obtained from the central and northern parts of the adjacent Nagssugtoqidian orogen to the south, and point to different uplift histories, which may suggest that the orogeny was not synchronous in the two regions.

Sudbury-type breccias in the Huronian Gowganda Formation near Whitefish Falls, Ontario: products of diabase intrusion into incompletely consolidated sediments?

1999 ◽  
Vol 36 (9) ◽  
pp. 1435-1448 ◽  
Author(s):  
CSJ Shaw ◽  
G M Young ◽  
C M Fedo
Keyword(s):  
Mafic Magma ◽  
Soft Sediment ◽  
Igneous Complex ◽  
Meteoritic Impact ◽  
Sudbury Igneous Complex ◽  
Complex Fault ◽  
Complex Shapes ◽  
Abundant Evidence ◽  
Sediment Deformation ◽  
Chemical Evidence

Sudbury breccias are commonly attributed to meteoritic impact at about 1.85 Ga in the vicinity of the Sudbury Igneous Complex. In the Whitefish Falls area, about 75 km southwest of Sudbury, similar breccias are widely developed in argillites of the ~2.3 Ga Gowganda Formation. There is abundant evidence of "soft sediment" deformation of the Huronian sediments in the form of complex "fault" contacts, clastic dyke intrusions, and chaotic folding. These movements appear to have been penecontemporaneous with intrusion of highly irregular diabase bodies, which are interpreted as being older than the ~2.2 Ga Nipissing diabase. Complex shapes of diabase bodies and highly irregular contact relationships between diabase and argillites, including intrusions of sediment veins into diabase, support intrusion of the diabase into incompletely consolidated sediments. These data, together with chemical evidence of mixing of diabase, argillite, and other materials in the breccia bodies, suggest that the breccias at Whitefish Falls may have formed as a result of interaction between hot mafic magma and semiconsolidated, water-rich mud, more than 350 Ma prior to formation of the Sudbury Igneous Complex and attendant phenomena that are presumed to be impact related.

On the depth of crater excavation and melting during the Sudbury impact: geochemical evidence from chilled impact melt dykes

2020 ◽  
Author(s):  
Alexander Kawohl ◽  
Hartwig E. Frimmel ◽  
Wesley E. Whymark ◽  
Andrejs Bite
Keyword(s):  
Continental Crust ◽  
Bulk Composition ◽  
Geochemical Data ◽  
Tectonic Deformation ◽  
Target Area ◽  
Upper Crust ◽  
Igneous Complex ◽  
Impact Melt ◽  
Sudbury Igneous Complex ◽  
The Impact

<p>The 1.85 Ga Sudbury Igneous Complex, Canada, is the remnant of a ~3 km thick impact-generated crustal melt sheet, caused by a 10-15 km large chondritic asteroid or comet that had left behind an impact structure of ~200 km prior to tectonic deformation und subsequent erosion. However, less is known about how deep the impactor penetrated the continental crust and where the source of the impact melt was. Mixing models including radioisotopes and trace elements on locally exposed country rocks have been used to evaluate their relative contribution to the impact melt. Based on this, Darling et al. (2010) have argued for shallow melting of the upper crust (UCC) only, either due to an oblique impact and/or a low-density bolide (comet). In contrast, the abundance of siderophile elements in impact melt-rocks was taken as evidence of a lower crustal source (Mungall et al. 2004), i.e. overlying rocks of the middle and upper crust must have been removed during the crater excavation stage. U-Pb age data on zircon xenocrysts also point to the involvement of rock types not exposed on surface (Petrus et al. 2016) in agreement with theoretical simulations, which have predicted a >20 km deep but unstable transient cavity (Ivanov & Deutsch 1999).</p><p>Large-scale (10s of km) and well-exposed impact melt dykes are a unique feature of Sudbury. The dykes are of granodioritic/quartz dioritic composition and are interpreted as clast-laden melt injections into the basement instantaneously after the impact (Pilles et al. 2018). Their vitric margins and distal extremities should therefore approximate the undifferentiated bulk composition of the Sudbury Igneous Complex prior to sulfide saturation. A compilation of published and new geochemical data of these dykes reveal a remarkably strong affinity (r<sup>2</sup> >0.989) to the average middle continental crust (MCC) as given by Rudnick & Gao (2014), especially in terms of major elements and fluid-immobile transition metals (Th, Zr, Hf, Nb, Ta, Ti, Sc, REE). The dykes are, however, significantly enriched in Ni, Cu and Cr, and to a lesser extent in V, Co and P relative to the typical UCC and MCC. A systematic loss of volatiles (Tl, Cd, Sn, Zn, Pb, Ag, Cs, Rb, Na, K, Ga, As) compared to either crustal model is not evident. These new observations favour a scenario in which the impactor and supracrustal rocks in the target area became vaporized and ejected. Shock melting affected predominantly the middle crust of the Canadian Shield. We also propose that the rocks that contributed to the impact melt were, on average, more mafic than the typical UCC and MCC. This is consistent with the report of exotic mafic-ultramafic xenoliths within the Sudbury Igneous Complex (Wang et al. 2018) and its anomalously high PGE concentrations (Mungall et al. 2004). (Ultra-)mafic rocks hidden at mid-crustal depth were a likely source of Ni-Cu-PGE-Co and gave rise to world class ore deposits presently mined at Sudbury. Such (ultra-)mafic intrabasement body might also explain the 1200 km<sup>2</sup> Temagami magnetic anomaly in the eastern vicinity of the Sudbury Complex.</p>

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