Palaeotopography of the northern portion of the Telychian (Silurian) turbidite basin in central Wales

James, D. M. D.

doi:10.1002/gj.1028

Cited by 3 publications

(2 citation statements)

References 19 publications

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“…The early Telychian parts of the Caban Conglomerate Formation, which post-date the Ystrad Meurig Grits, formed one of several supply routes to the early parts of the Devil's Bridge Formation (Davies et al 2006), a turbidite system, up to 600 m in thickness, that blanketed much of the basin west of the Central Wales Lineament during early to middle Telychian times (Cave & Hains, 1986;Davies et al 1997;James, 2005).…”

Section: Stratigraphic Contextmentioning

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: Stratigraphic Contextmentioning

confidence: 99%

“…2006), a turbidite system, up to 600 m in thickness, that blanketed much of the basin west of the Central Wales Lineament during early to middle Telychian times (Cave & Hains, 1986; Davies et al . 1997; James, 2005).…”

Section: Stratigraphic Contextmentioning

confidence: 99%

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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Turbidite pathways, pore-fluid pressures and productivity in the Central Wales Orefield

James

2011

JGS

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Lodes in the Central Wales Orefield are mineralized oblique-slip normal faults that postdate the regional joints. They developed shortly after the (Acadian) deformation of the Welsh Basin in the late Early Devonian and many were reactivated with further mineralization in the early Carboniferous. Although orefield extent is clearly centred on the structural culmination around the Plynlimon Dome the major areas of lead–zinc production are strongly off-centered. These areas lie on the depositional pathways of three horizons of late Ordovician–early Silurian massive turbidite sandstones. It is argued that these basin-floor sand bodies are preferential sites of lode nucleation and that their distribution controls the size and abundance of the lodes and hence their chances to link laterally and at depth. This in turn controls their ability to capture and transmit mineralizing fluids and thus their chances of hosting large ore deposits. The prime cause of high fluid pressure gradients during the first phase of mineralization was rapid uplift of ‘tight' rock with dehydration fluids from Acadian metamorphism. Second phase fluids probably originated as seawater and were driven by convective overturn at essentially hydrostatic pressures. The stratigraphic control of lode productivity has implications for mineral exploration in such terranes.

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Marine redox dynamics and biotic response to the mid-Silurian Ireviken Extinction Event in a mid-shelf setting

Wang,

Wignall,

Xiong

et al. 2024

JGS

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The early Silurian Llandovery–Wenlock boundary interval was marked by significant marine perturbations and biotic turnover, culminating in the Ireviken Extinction Event (IEE) and the Early Sheinwoodian Carbon Isotope Excursion (ESCIE). Here, we apply multiple independent redox proxies to the early Wenlock Buttington section, which was deposited in a mid-shelf location in the Welsh Basin, UK. To account for regional geochemical variability in marine sediments due to factors such as sediment provenance, we first define oxic baseline values for the Welsh basin, utilizing deeper water, well-oxygenated intervals of late Llandovery age. Our approach documents unstable, oscillating redox conditions on the mid shelf at Buttington. We suggest that these dynamic redox fluctuations are likely to relate to changes in the position of the chemocline or a migrating oxygen minimum zone. Benthic biota such as trilobites, brachiopods, bivalves and gastropods appear to have been relatively unaffected by fluctuating oxic-ferruginous conditions, but were more severely impacted by the development of euxinia, highlighting the inhibiting role of toxic sulfides. By contrast, the redox perturbations appear to have placed extreme stress on graptolites, causing many extinction losses regardless of the specific development of euxinia. Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system Supplementary material: https://doi.org/10.6084/m9.figshare.c.7165009

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Palaeotopography of the northern portion of the Telychian (Silurian) turbidite basin in central Wales

Cited by 3 publications

References 19 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

Turbidite pathways, pore-fluid pressures and productivity in the Central Wales Orefield

Marine redox dynamics and biotic response to the mid-Silurian Ireviken Extinction Event in a mid-shelf setting

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