On the sources of uranium in some Scottish Caledonian granites

Halliday, A. H.

doi:10.1180/minmag.1981.044.336.09

Cited by 8 publications

(5 citation statements)

References 22 publications

(24 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Confirmatory evidence was presented by Blaxland et al (1979) who showed that the common Pb isotopic compositions in K-feldspars from the Caledonian granitoids became more radiogenic southwards. Halliday (1981) pointed out a general correlation between U contents of zircons and the initial Pb isotopic composition of the K-feldspars from which it was argued that the U and Pb had to be dominated by a crustal component regardless of the original source of the magma. It was also pointed out that the Lewisian complex was not directly a major component although recycled and admixed with younger crust (such as in later sediments) it was an important component.…”

Section: Isotopic Constraintsmentioning

confidence: 99%

Geochemical contrasts between late Caledonian granitoid plutons of northern, central and southern Scotland

Stephens

Halliday

1984

Transactions of the Royal Society of Edinburgh: Earth Sciences

Self Cite

105

View full text Add to dashboard Cite

New major- and trace-element data for granitoid plutons from the Grampian Highlands, the Midland Valley and the Southern Uplands of Scotland are presented and discussed. The study is restricted to ‘late granitoids’ (all younger than 430 Ma); the term ‘granitoid’ is used in a wide sense to encompass all plutonic components of a zoned intrusion of this age, sometimes including diorites and ultrabasic cumulate rocks. The data indicate that as a whole the province is chemically high-K calc-alkalic. Other notable enrichments are in Sr and Ba, and a marked geographical difference in these trace-elements is found between plutons of the SW Grampian Highlands and those of the Southern Highlands, the Midland Valley, and the Southern Uplands. Plutons of the NE Highlands tend to be more geochemically evolved than those further SW and those of the Midland Valley and Southern Uplands.When petrographical and geochemical data are considered, three plutonic suites are recognised: (1) the Cairngorm suite comprising plutons of the NE Highlands, (2) the Argyll suite comprising plutons from the SW Highlands, and (3) the S of Scotland suite comprising plutons from the Southern Highlands, Midland Valley and the Southern Uplands excluding Criffell and the Cairnsmore of Fleet. It is proposed that the more acidic granitoids are dominantly the products of I-type crustal sources, but certain diorites and the more basic members of zoned plutons have a substantial mantle component. The elevated Sr and Ba levels in granitoids of the Argyll suite may reflect the influence of incompatible-element-rich fluids from the mantle in the petrogenesis of this suite. The relatively anhydrous pyroxene-mica diorites of the S of Scotland suite are richer in Ni and Cr and appear to represent mantle-derived melts. The relationships between these data and already published isotopic data are discussed.

show abstract

Section: Isotopic Constraintsmentioning

confidence: 99%

Geochemical contrasts between late Caledonian granitoid plutons of northern, central and southern Scotland

Stephens

Halliday

1984

Transactions of the Royal Society of Edinburgh: Earth Sciences

Self Cite

105

View full text Add to dashboard Cite

show abstract

“…No interpretative lead isotope studies have been undertaken on Southern Uplands galenas since the single-stage model ages reported by Moorbath (1962). Studies of feldspar lead from Caledonian granites in the region have been reported (Blaxland et al 1979;Halliday 1981), and U-Pb, Rb-Sr and O isotopic relationships suggest that the granite magmas could have incorporated a significant quantity of Southern Uplands Lower Palaeozoic sediments (SULPS) (Pidgeon & Aftalion 1978;Halliday et al 1979. Lead in sulphide deposits further S in the northern Pennines is attributed a granitic source by Russell (1978) and Dunham et al (1978), which is consistent with lead isotope evidence from Mitchell and Krouse (1971).…”

Section: Mineralisation N and S Of The Midland Valleymentioning

confidence: 99%

“…Studies of lead isotope variations in whole-rock samples, particularly granitoids (Blaxland et al 1979;Halliday 1981;Clayburn et al 1983) emphasise that the isotopic evolution of lead in Scotland is complex, and that the establishment of a single satisfactory model to explain data is not always possible. In the Highlands in particular, one would expect lead to consist of a complex mixture derived from sedimentary and metasedimentary rocks of varying ages, which might include detritus eroded from various levels in the Lewisian complex representing parts of the lower and upper crust.…”

mentioning

confidence: 99%

“…In the Highlands in particular, one would expect lead to consist of a complex mixture derived from sedimentary and metasedimentary rocks of varying ages, which might include detritus eroded from various levels in the Lewisian complex representing parts of the lower and upper crust. Additional reservoirs of lead might include metamorphic products of the Grenvillian, Knoydartian and Caledonian episodes, which in part reached granulite facies during orogenic events (Halliday 1981;Clayburn et al 1983). Volcanic rocks in the Dalradian Supergroup have also been postulated as a source of lead (Swainbank et al 1981).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Interpretation of Pb isotope compositions of galenas from the Midland Valley of Scotland and adjacent regions

Parnell

Swainbank

1984

Transactions of the Royal Society of Edinburgh: Earth Sciences

View full text Add to dashboard Cite

The lead isotope compositions of 61 galenas from central and southern Scotland vary markedly between different regions. Most galenas from the southern Grampian Highlands yield isotope ratios (206Pb/204Pb 17·77 ± 0·25, 207Pb/204Pb 15·47 ± 0·05, 208Pb/204Pb 37·63 ± 0·26) less radiogenic than those from Midland Valley galenas (18·22 ± 0·12, 15·55 ± 0·05, 38·13 ± 0·14) whilst galena lead from the Southern Uplands (18·28 ± 0·12, 15·56 ± 0·03, 38·21 ± 0·18) is more radiogenic than that from the southern Midland Valley (18·12 ± 0·06, 15·52 ± 0·02, 38·06 ±0·10). The change in isotopie composition across the Highland Boundary fault reflects the presence or absence of Dalradian rocks which included a magmatic component of lead. Galenas from the Dalradian sequence in Islay, where igneous rocks are lacking, have a composition (18·14±0·04, 15·51±0·01, 37·90±0·02) more like Midland Valley galenas. In the Southern Uplands, galenas yield lead isotope ratios similar to those of feldspars from Caledonian granite (18·30 ± 0·14, 15·57 ± 0·04, 37·96 ± 0·15) analysed by Blaxland et al. (1979). The similar ratios reflect the incorporation of Lower Palaeozoic sedimentary rocks into the granite magma, rather than a granitic source for the mineralisation. The granites were then thermal-structural foci for later mineralising fluids which leached metals from the surrounding rocks. Within the Midland Valley, galenas hosted in Lower Devonian-Lower Carboniferous lavas are notably more radiogenic (18·31 ±0·12, 15·58 ± 0·06, 38·20 ± 0·16) than sediment-hosted galenas (18·14 ± 0·07, 15·52 ± 0·02, 38·08 ± 0·10). The Devonian lavas at least may have inherited lead from subducted (? Lower Palaeozoic) rock incorporated in the primary magma.

show abstract

“…This Mid-Grampian Line has been taken to represent a fossil Dalradian continental margin since it marks the approximate boundary between exposed Mointan and Dalradian rocks (Halliday et al 1985) and is therefore thought to mark a distinct increase in the age of the lower crust in this region. Evidence from Blaxland et al (1979) and Halliday (1981) that common Pb isotopic corn- positions of granitoids become more radiogenic southwards has also been taken to indicate a southerly decrease in the availability of ancient granulite-facies material in the Scottish lower crust (Halliday 1984).…”

Section: Introductionmentioning

confidence: 99%

The geochemistry of Dinantian volcanism in south Kintyre and the evidence for provincialism in the southern Scottish mantle

Smedley

1988

Contr. Mineral. and Petrol.

View full text Add to dashboard Cite

Scottish Dinantian transitional to mildly alkaline volcanism is represented by abundant outcrops in the Midland Valley, Southern Uplands and Highlands provinces. Dinantian volcanic rocks from Kintyre in the Scottish Highlands range in composition from basalt through basaltic hawaiite, hawaiite, mugearite and benmoreite to trachyte, the compositions of the evolved types being largely due to differentiation from the basaltic parents.Recent geochemical investigations of Scottish Caledonian granitoids, Siluro-Devonian Old Red Sandstone (ORS) lavas and xenolith suites from numerous vents and dykes of Permo-Carboniferous to Tertiary age have revealed that the Scottish crust and upper mantle both increase in age and are increasingly enriched in incompatible elements towards the north and northwest. The upper mantle and lower crust below the Highlands province are therefore largely considered to be more enriched and in parts older than those below the Midland Valley and Southern Uplands. Dinantian alkali basalts from these latter two provinces have eNd values predominantly in the range + 3 to +6, initial S7Sr/86Sr values of 0.7029-0.7041 and 2~ 2~ values of 15.48-15.60. However, similar basalts from Kintyre and Arran in the Highlands have lower eNd (+ 0A to +3.4) and 2~176(for given 2~176 ratios; 15.49-15.51) and slightly higher 87Sr/86Sr (0.7033-0.7046). This regional variation correlates well with the differences seen between Midland Valley and Highland magmas in the ORS calc-alkaline suite (Thirlwall 1986) and it is suggested that both the ORS and Dinantian basic rocks are derived from similar types of mantle, although no lithospheric slab component is present in the later Dinantian suites. Isotopically-distinct portions of mantle therefore appear to have been present below the Highland and Midland Valley-Southern Upland provinces from at least Caledonian to Carboniferous times. The combined incompatible element and Sr-Nd-Pd isotopic evidence from Kintyre and Arran basaltic rocks does not allow unequivocal distinction between a lithospheric mantle and a sublithospheric mantle source. The observed correlation between isotopic composition of Dinantian basalts and the chemical composition of the lithosphere, together with the apparent involvement of long-term separated source reservoirs suggests that Kintyre and Arran lavas were derived largely from a lithospheric mantle source. On the other hand, the isotopic enrichment of Kintyre basaltic rocks is not extreme; trace element and isotopic compositions are still comparable to modern OIB. Sublithospheric mantle could therefore also be a viable source for Kintyre and Arran Dinantian volcanism.

show abstract

On the sources of uranium in some Scottish Caledonian granites

Cited by 8 publications

References 22 publications

Geochemical contrasts between late Caledonian granitoid plutons of northern, central and southern Scotland

Geochemical contrasts between late Caledonian granitoid plutons of northern, central and southern Scotland

Interpretation of Pb isotope compositions of galenas from the Midland Valley of Scotland and adjacent regions

The geochemistry of Dinantian volcanism in south Kintyre and the evidence for provincialism in the southern Scottish mantle

Contact Info

Product

Resources

About