Geological relationships within an Ordovician shale belt in Galloway

Stone, P.

doi:10.1144/sjg17030205

Cited by 2 publications

(1 citation statement)

References 6 publications

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“…Leinster, Newry and Criffell; Fig. 1) occur together with deformed hypabyssal dyke swarms in this region (Blyth, 1949;Stone, 1981;Reynolds, 1931). This association suggests an interplay between local diapiric and regional tectonic strains (e.g.…”

Section: Introductionmentioning

confidence: 83%

Late Caledonian granitoids and timing of deformation in the Iapetus suture zone of eastern Ireland

Murphy

1987

Geol. Mag.

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Late Caledonian granitoids, (c. 400 Ma) in the zone of the Iapetus suture provide a datum against which current models for the relative timing of deformation can be tested. One such granitoid adjacent to the proposed suture Mine' in eastern Ireland is now buried by an Upper Palaeozoic cover. It is identified geophysically by a negative Bouguer anomaly with no magnetic signature, and geologically by a hypabyssal dyke swarm and hornfels metamorphism. The timing of intrusion of the granitoid is shown to have occurred during the continuing end-Silurian/early-Devonian deformation. Other members of this widespread suite in Ireland show features consistent with diapiric intrusion during the later stages of the deformation. This evidence brackets the age of regional deformation as continuing during granite emplacement and cooling (c. 400 Ma). The unifying characteristics of the straddling granitoid suite, coupled with a sinistrally transpressive deformation, in this broad suture zone are interpreted in terms of a continental collision which climaxed in late-Silurian/early-Devonian time.

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Section: Introductionmentioning

confidence: 83%

Late Caledonian granitoids and timing of deformation in the Iapetus suture zone of eastern Ireland

Murphy

1987

Geol. Mag.

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Disseminated and epigenetic Pb–Zn mineralisation in Ordovician mudstone, Galloway

Stone

Leake

1984

SJG

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Synopsis Significant base metal anomalies in drainage and overburden in the Penkiln Burn area, near Newton Stewart, are spatially associated with the outcrop of a sequence of siliceous mudstone, siltstone and chert. Pb is particularly enriched in drainage samples, reaching approximately 1% close to a mineralised gossan zone, mainly in the secondary lead phosphate plumbogummite. Three varieties of mineralisation have been recognised: Early fine disseminations, chiefly sphalerite and pyrite, in the mudstone and siltstone characterised by Zn levels between 500 and 1000 ppm. Fine stratiform pyrite laminae adjacent to the mineralised horizons and interbedded cherts containing disseminated sphalerite support a probable syngenetic, exhalative origin. A swarm of dioritic minor intrusions carry disseminated sulphides and have elevated metal contents, most notably Zn (up to 2000 ppm). This mineralisation is considered to have a primary igneous source. Mineralisation related to veining and alteration involving both the remobilisation of the disseminated sulphides and hydrothermal effects. Thin quartz veinlets containing sphalerite and galena locally elevate base metal levels so that Pb reaches 7000 ppm in places. The veins usually contain some secondary alteration minerals which become dominant at the altered margins of dykes and in fault-bounded gossans where a low temperature mineral assemblage includes plumbogummite and beudantite. In the gossans Pb ranges up to 4.5% but Zn has been preferentially leached.

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Geological relationships within an Ordovician shale belt in Galloway

Cited by 2 publications

References 6 publications

Late Caledonian granitoids and timing of deformation in the Iapetus suture zone of eastern Ireland

Late Caledonian granitoids and timing of deformation in the Iapetus suture zone of eastern Ireland

Disseminated and epigenetic Pb–Zn mineralisation in Ordovician mudstone, Galloway

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