Sulphur, carbon and oxygen isotope studies of early Variscan mineralisation and Pb-Sb vein deposits in the Cornubian orefield: implications for the scale of fluid movements during Variscan deformation

Clayton, R. E.; Spiro, Baruch

doi:10.1007/s001260050244

Cited by 16 publications

(5 citation statements)

References 36 publications

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“…10 Cu, Fe, Pb, Sb, and Zn (Clayton et al 1990;Clayton and Spiro 2000). A broadly similar association is hosted by quartz-carbonate veins in the Looe Basin succession near Loddiswell (Stanley et al 1990b).…”

Section: Accepted M Manuscriptmentioning

confidence: 93%

Indium mineralisation in SW England: Host parageneses and mineralogical relations

Stickland

Rollinson

Shail

2016

Ore Geology Reviews

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Section: Accepted M Manuscriptmentioning

confidence: 93%

Indium mineralisation in SW England: Host parageneses and mineralogical relations

Stickland

Rollinson

Shail

2016

Ore Geology Reviews

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“…Remobilization of metals from the metasediments would have been related to Variscan metamorphism and deformation, as is the case for polymetallic veins in the French Massif Central (e.g., Marcoux et al, 1988), Sb mineralization in Germany (Wagner and Cook, 2000) and Pb-Sb vein deposits in Cornwall, U.K. (Clayton and Spiro, 2000).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Antimony quartz and antimony-gold quartz veins from northern Portugal

Neiva

Andráš

Ramos

2006

Geochimica et Cosmochimica Acta

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In northern Portugal, there are two main areas containing antimony, lead-antimony and antimony-gold deposits. The antimony and lead-antimony quartz breccia veins from the Bragança district are mainly hosted by Silurian phyllites. The antimonygold quartz breccia veins from the Dú rico-Beirã region are mainly hosted by the Cambrian schist-metagraywacke complex and also Ordovician phyllites and quartzites. These veins are up to 200 m long, but their thickness ranges from a few centimeters to 3.6 m.In each deposit, some minerals show multiple paragenetic settings, suggesting that mineral precipitation is a polyphase process. Arsenopyrite, pyrite and pyrrhotite are the earliest sulfides to form. The earliest generation of euhedral gold is earlier than or contemporaneous with arsenopyrite and earlier than pyrrhotite and pyrite. Berthierite and stibnite are the most important antimony-bearing minerals. Stibnite is most abundant. Later anhedral gold grains are present within fractures between arsenopyrite and stibnite and in stibnite, which is partially replaced by the gold. Gold inclusions rarely occur in quartz. Carbonates precipitated in the last hypogene stage.The drastic fluid cooling during the mineralizing event was an important cause of mineralization. However, acidification of fluids might have been the main mechanism for stibnite precipitation, as it would have destabilized Sb(OH) 3 . Gold associated with arsenopyrite, pyrite and quartz was probably carried as a bisulfide complex by the early aqueous carbonic fluid with 2 wt% equiv. NaCl at 290-340°C, while the late generation of gold associated with berthierite and stibnite was transported as a bisulfide complex by the H 2 O-NaCl (2 wt% equiv.) fluid at 128-225°C.Variscan folding, long deep faults, shear zones, and deformation in the Bragança district and Dú rico-Beirã region would have provided anomalous crustal heat flow to sustain the extensive and long-lived hydrothermal activity. The metamorphic fluids derived from the country metasediments and heated meteoric water, which also leached metals from these metasediments, were responsible for the origin of the mineralized veins. The lead isotopic data for stibnite indicate a homogeneous source of lead of crustal origin, from a dominant metasedimentary source, for the studied antimony, lead-antimony and antimony-gold quartz veins. This is consistent with related European mineralizations.Previously, hydrothermal alteration halos around Archaean orogenic gold deposits have been documented at the metre to 100 m scale centred around the gold lode. The preferred model for this spatial relationship and the available fluid inclusion and stable isotope data was a one fluid model with gold deposition largely caused by fluid-wallrock reactions and phase separation. Camp-scale studies in the St. Ives gold camp and at the Kanowna Belle and Wallaby deposits in Western Australia have documented camp-scale hydrothermal alteration cells which are asymetric to gold.Several hundred metres to kilometre scale magnetite-pyrite or ...

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“…In Cornubia the batholith is intruding Middle Devonian-Lower Carboniferous sediments. The pre-Variscan metasedimentary sulphur is significantly depleted in 34S (-34 to -26%0; Clayton & Spiro 2000) and veins hosted by these contain sulphides with ~348 of-15 to +2%0 (Jackson et al 1989;Clayton & Spiro 2000), reflecting mixing between sedimentary and igneous sulphur sources. In Nova Scotia the Variscan front tracks further north and the South Mountain batholith is emplaced into the Cambro-Ordovician Meguma Group (Avalonian) shales and greywackes that have a dominant positive tenor (-4 to +26%o; Poulsen et al 1991).…”

Section: Sulphur and Metal Correlations Along Strike To The Appalachimentioning

confidence: 98%

Terrane and basement discrimination in northern Britain using sulphur isotopes and mineralogy of ore deposits

Lowry

Boyce

Fallick

et al. 2005

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This study of four well characterized and adjacent terranes in Northern Britain outlines the sulphur isotope variations, assesses the overall importance of crustal and mantle sulphur, and presents a model that can be applied to terrane distinction throughout the North Atlantic Caledonides. The characteristics of metal components within the mineralization provide additional information that can be related to the nature of underlying basement and events from the onset of sedimentation to the cessation of mineralization within stratigraphically linked packages of rock.The ~345 data show that the dominant crustal units in each terrane, whether upper crustal sediments or cratonic basement, provide the main alternative sulphur source to the mantle and act also as the main contaminant of subcrustal melts. The 834S values of granitoidrelated mineralization are either within the subcrustal melt-range of -3%0 to +3%0 or deviate toward the values of major crustal units in the terrane, i.e. toward 345 depletion in the Southern Uplands and toward 345 enrichment in the Lakesman and Grampian terranes. More complex mineralization in the Northern Highland terrane is linked to the presence of thick North Atlantic craton beneath upper crustal metasediments. Across the region the vein systems beyond the influence of magmatic components represent homogenized sulphur, metals and fluids from local upper crustal units. The sulphur isotope data and style of mineralization for the British terranes are compared with terranes of similar age along strike in Eastern Canada revealing notable correlations. Anderson et al. 1989;Hall et al. 1991;Lowry et al. 1991a;Scott et al. 1991;Steed & Morris 1997), and pyrite in metasediments (e.g.Hall et aL 1987, 1988, 1994a, b). Our analysis of this dataset highlights distinctive isotopic variations, which not only provides further evidence for the delineation of the putative terrane boundaries, but also suggests deep crustal and possibly subcrustal variations across the region.

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Sulphur, carbon and oxygen isotope studies of early Variscan mineralisation and Pb-Sb vein deposits in the Cornubian orefield: implications for the scale of fluid movements during Variscan deformation

Cited by 16 publications

References 36 publications

Indium mineralisation in SW England: Host parageneses and mineralogical relations

Indium mineralisation in SW England: Host parageneses and mineralogical relations

Antimony quartz and antimony-gold quartz veins from northern Portugal

Terrane and basement discrimination in northern Britain using sulphur isotopes and mineralogy of ore deposits

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