The Caban Conglomerate and Ystrad Meurig Grits Formation — nested channels and lobe switching on a mud-dominated latest Ashgill to Llandovery slope-apron, Welsh Basin, UK

Davies, Jeremy; Waters, R. A.

doi:10.1007/978-94-011-1234-5_27

Cited by 13 publications

(12 citation statements)

References 21 publications

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“…A comparable situation occurred with the expansion of the Caban-Ystrad Meurig system to its greatest lateral extent during a period of sea-level highstand, coincident with the cyphus graptolite Biozone (Davies & Waters, 1995). This expansion was accompanied by deposition of the Allt-y-clych Conglomerate and continued sedimentation in the Ystradffin tract.…”

Section: (3) a Late Aeronian Transgression (Or Transgressions)mentioning

confidence: 66%

“…1). The most extensive of these, the Caban-Ystrad Meurig system, crops out on the NW margin of the Tywi Lineament near the town of Rhayader, and is represented by a coeval succession exposed in the core of the Teifi Anticline (Lapworth, 1900;Jones, 1922;Kelling & Woollands, 1969;Davies & Waters, 1995;Davies et al 1997;J. Holroyd, unpub.…”

Section: Stratigraphic Contextmentioning

confidence: 99%

“…latest Ordovician (late Hirnantian) to early Telychian times and is interpreted as recording the deposition of a series of small, unconfined distributory fans (Ystrad Meurig Grits), supplied by a narrow channel-overbank system (Caban Conglomerate: Davies & Waters, 1995;Davies et al 1997;Davies, Waters & Copus, 1999). The Allt-y-clych Conglomerate (Andrew, 1925), contained within the Rhuddanian proximal slope apron sequence, is preserved along the eastern margin of the Tywi Lineament and comprises a thin sequence that may link with the Caban-Ystrad Meurig system (Davies et al 1997;Davies, Waters & Copus, 1999).…”

Section: Stratigraphic Contextmentioning

confidence: 99%

“…The Dinas Formation may mark the site of a smaller, younger lobe, the location of which, offset to the south, was in part determined by the relief created by the earlier Ystradffin feature (cf. Davies & Waters, 1995). The early (Aeronian) part of the Nant Brianne Formation records a period of laterally confined sand and gravel deposition.…”

Section: C Nant Brianne Formationmentioning

confidence: 99%

“…1; Morton et al 1992). These define narrow submarine corridors via which coarse clastic sediment was routed across the proximal parts of the slope apron, as well as lobelike constructional features of similar material on the slope apron surface (Cave & Hains, 1986;Davies & Waters, 1995). As with many modern systems (e.g.…”

Section: Introductionmentioning

confidence: 99%

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A new Early Silurian turbidite system in Central Wales: insights into eustatic and tectonic controls on deposition in the southern Welsh Basin

et al. 2008

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-The newly recognized Nant Brianne turbidite system was a focus of laterally supplied coarse-grade sediment deposition that, along with the Caban-Ystrad Meurig system, punctuated late Hirnantian to early Telychian, mudstone-dominated slope apron deposition along the SE margin of the southern Welsh Basin. Geological mapping coupled with detailed biostratigraphy enable the depositional influence of sea-floor topography, an active Llyn Brianne Fault and eustatic sea-level changes to be tracked. The latter may represent 'far field' effects relating to the retreat and advance of contemporary Gondwanan ice sheets. Slope apron mudstone facies reveal a strong response to high order eustatic events; however, the response of contemporary, easterly sourced, coarse-grade turbidite systems was more complex, with some periods of increased sand and gravel input coinciding with times of rising global sea level. These anomalous relationships are explained by invoking a series of smaller-scale movements in marine base level. It was the interaction of these lower order events with the main eustatic cycles that appears to have been the primary control on sand and gravel input to the Welsh Basin. An early Telychian expansion of the Nant Brianne turbidite system records a marked increase in tectonically generated sediment at a time of palaeo-plate collision between Baltica/Avalonia and Laurentia before intra-and peri-basinal faulting led to its abandonment as a supply path to the basin centre.

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Section: (3) a Late Aeronian Transgression (Or Transgressions)mentioning

confidence: 66%

Section: Stratigraphic Contextmentioning

confidence: 99%

Section: Stratigraphic Contextmentioning

confidence: 99%

Section: C Nant Brianne Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new Early Silurian turbidite system in Central Wales: insights into eustatic and tectonic controls on deposition in the southern Welsh Basin

et al. 2008

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Deep-basin dropstones in the early Silurian of Wales: a clue to penecontemporaneous, near-shore algal forests

Zalasiewicz

Taylor

2001

Proceedings of the Geologists' Association

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A revised sedimentary and biostratigraphical architecture for the Type Llandovery area, Central Wales

et al. 2012

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-The global standard for the Llandovery Series (early Silurian) in central Wales is re-assessed in the light of detailed geological surveying, biostratigraphical sampling and a rigorous examination of published datasets. A new sedimentary and biostratigraphical architecture is presented. Key graptolite, brachiopod, acritarch and, for the first time, chitinozoan assemblages are critically assessed. Upper Hirnantian to Aeronian strata record events that followed the Late Ordovician glacial maximum and comprise a series of progradational sequences bounded by flooding surfaces, but inferred still to be glacioeustatic in origin. Significant faunal renewals associated with many of the flooding levels underpin their potential for international recognition. Compound non-sequences are a feature of proximal parts of the system where erosion associated with fault footwall uplift was an important process. Extensive slump sheets contribute to further stratal loss and displacement in distal facies. A re-assessment of the Aeronian Stage GSSP reveals shortcomings with the biostratigraphical criteria used in its selection. Telychian portions of the succession display the disrupting effects of intraWenlock synsedimentary sliding; hence the relevance of key published fossil assemblages and the criteria used to erect the stage GSSP are undermined. However, the Llandovery area remains one of the best studied early Silurian successions in the world. This, together with regional considerations, supports the retention of the series standard in mid Wales where the contiguous deep-water basinal succession affords internationally cited exposure of richly graptolitic facies for the whole series and, significantly, for the post-sedgwickii Biozone interval.

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The Caban Conglomerate and Ystrad Meurig Grits Formation — nested channels and lobe switching on a mud-dominated latest Ashgill to Llandovery slope-apron, Welsh Basin, UK

Cited by 13 publications

References 21 publications

A new Early Silurian turbidite system in Central Wales: insights into eustatic and tectonic controls on deposition in the southern Welsh Basin

A new Early Silurian turbidite system in Central Wales: insights into eustatic and tectonic controls on deposition in the southern Welsh Basin

Deep-basin dropstones in the early Silurian of Wales: a clue to penecontemporaneous, near-shore algal forests

A revised sedimentary and biostratigraphical architecture for the Type Llandovery area, Central Wales

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