Silurian turbidites used to reconstruct a volcanic terrain and its Mesoproterozoic basement in the Irish Caledonides

Menuge, Julian F.; Williams, David M.; O'connor, P. D.

doi:10.1144/gsjgs.152.2.0269

Cited by 16 publications

(9 citation statements)

References 33 publications

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“…The Lettergesh sandstones have a significant detrital volcanic component. It has been suggested that the rapid deposition of such a thick sedimentary succession was related to a major volcanic episode near the basin at this time (Williams, O'Connor & Menuge, 1992;Menuge, Williams & O'Connor, 1995). The deposition of the sandstones resulted in the accumulation of some 1300 m (compacted) of sediment between the uppermost Llandovery and the Lower Wenlock, possibly over two to three million years.…”

Section: Conglomerates and Sea-level Variationmentioning

confidence: 96%

Tectonic control on sedimentation during transgression: a case study from Silurian successions in Ireland and Scotland

O'connor

Williams

1999

Geol. Mag.

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The Silurian succession of North Galway is relatively well constrained in terms of environmental analysis and, in its lower half, palaeontologically. The initiation of a late Llandovery marine transgression can be demonstrated over fluviatile red sandstones. The deposition of shallow-water conglomerates at the base of a turbidite sequence within the succession indicates the long-lived presence of a channel system that was probably fault controlled. The back-stripping method allows a subsidence curve to be constructed for this succession. It demonstrates an initial period of rapid rift-related subsidence followed by a short-lived hiatus that may be due to the cessation of subduction in this part of the Caledonides. A comparison of the Galway subsidence curve with that of the Silurian succession at Girvan in Scotland shows strong, but diachronous, similarities. This tends to support an earlier suggestion that they formed part of a single but partitioned basin throughout most of the Silurian period. Although the eustatic fall in sea level at the Llandovery–Wenlock boundary can be recognized, the influence of tectonic regime and sedimentation rates were the controlling factors in determining relative sea levels.

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Section: Conglomerates and Sea-level Variationmentioning

confidence: 96%

Tectonic control on sedimentation during transgression: a case study from Silurian successions in Ireland and Scotland

O'connor

Williams

1999

Geol. Mag.

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“…The much simpler east trending upright folding of the Silurian rocks of the Killary Harbour area (Menuge, Williams & O'Connor, 1995) and faulting, with small displacements (up to 1 km) across the Doon Rock and Salrock faults contrasts with the fault-controlled higher strains and up to biotite grade in the Silurian rocks of the Clew Bay area.…”

Section: Tectonic History Of the Silurian Rocksmentioning

confidence: 98%

Terrane amalgamation in the Clew Bay region, west of Ireland

Johnston

Phillips

1995

Geol. Mag.

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The Caledonides of the west of Ireland provide a well-exposed and well-mapped example of an oblique collision zone. The east-northeast trending Deer Park and Achill Beg Fault system is a crustal scale ductile sinistral strike-slip duplex of late Ordovician age, imbricating late Precambrian granulite facies lower crustal rocks, near eclogite facies supracrustal rocks, up to amphibolite facies Dalradian metasedimentary rocks and greenschist facies Cambro-Ordovician rocks. This fault system is correlated with a pre-

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“…Silurian rocks rest unconformably upon this sequence. A recent study has shown them to be derived from a young volcanic arc to the north (Menuge, Williams & O'Connor, 1995) and they are not discussed further here. The Ards Peninsula and the Cavan-Monaghan area of the Longford-Down massif are both part of the Central Terrane and contain elements of both the Northern (Ordovician) and Central (mainly Silurian) belts of Southern Uplands stratigraphy.…”

Section: Introductionmentioning

confidence: 97%

Terrane geochemistry contrasts across the Iapetus Suture in Ireland

1995

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In the Irish Caledonides, volcanism has been significant in terrane identification and in reconstructions of the Appalachian/Caledonian orogen. Crucial to these reconstructions is the recognition of ocean margins using obducted ocean floor relics (ophiolites) and supra-subduction zone volcanic assemblages. The volcanic rocks provide much evidence for the affinity of a terrane, however, by analogy with present day examples, the ocean floor sediments may provide the best way of tracing both ocean-floor magmatic activity, and continental source areas. This investigation shows that the Irish Lower Palaeozoic volcanogenic terranes can be discriminated in terms of their shale geochemistry, which also gives information on their provenance and environment of deposition. South Mayo shales are dominated by volcaniclastic material derived both from both an arc and from an ophiolitic source. The Northern and Central belts of the Central Terrane show very similar lithogeochemistries, apparently derived in part from intermediate to silicic volcanic complexes. The Ordovician-Silurian inliers that straddle the Suture Zone, here termed the Southern Domain, show a chemistry close to that of the Leinster Terrane, which, coupled with a greater degree of sea-floor weathering, suggests a terrane with sediment of both volcanic and continental provenance being deposited in deeper water further from land. Across the suture the Leinster Terrane shows a mature chemistry which clearly suggests a continental provenance, together with a volcanogenic input from supra-subduction volcanism. This maturity is probably due to slower rates of sedimentation with longer residence times for volcanic detritus, plus the existence of a deeply weathered continental basement.

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Silurian turbidites used to reconstruct a volcanic terrain and its Mesoproterozoic basement in the Irish Caledonides

Cited by 16 publications

References 33 publications

Tectonic control on sedimentation during transgression: a case study from Silurian successions in Ireland and Scotland

Tectonic control on sedimentation during transgression: a case study from Silurian successions in Ireland and Scotland

Terrane amalgamation in the Clew Bay region, west of Ireland

Terrane geochemistry contrasts across the Iapetus Suture in Ireland

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