The Ridgeway Conglomerate Formation of SW Wales, and its implications. The end of the Lower Old Red Sandstone?

Hillier, Robert D.; Williams, Brian P.

doi:10.1002/gj.1070

Cited by 19 publications

(11 citation statements)

References 96 publications

(142 reference statements)

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“…Burrowing possibly represents a depauperate Scoyenia ichnofacies (Buatois & Mángano, 2004). Similar deposits are observed in interpreted fan toe reaches of the ORS Ridgeway Conglomerate Formation (Hillier & Williams, 2007) and from ephemeral ORS floodplain lakes (e.g. Marriott & Wright, 2004).…”

Section: Trichrug Formation Distal Fan Lithofaciessupporting

confidence: 66%

“…The Skolithos burrows may infer opportunistic arthropod tracemakers (insects or arachnids) in moist softground sediment (see discussion below). Similar deposits are common in Siluro‐Devonian continental successions of the UK, for example, see Tunbridge (1981), Williams & Hillier (2004), Hillier & Williams (2007).…”

Section: Trichrug Formation Distal Fan Lithofaciesmentioning

confidence: 66%

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Alluvial fan and wetland interactions: evidence of seasonal slope wetlands from the Silurian of south central Wales, UK

Hillier¹,

Waters²,

Marriott

et al. 2010

Sedimentology

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Distal environs of the Ludlow-age Trichrug Formation from south central Wales (UK) detail deposition on the outer fringe of an ephemeral debris flowdominated alluvial fan. Debrites and subordinate sheetflood deposits are interbedded with sporadic thin sandstone-dominated heterolithic units deposited in shallow, ephemeral ponds in the axial valley. The latter slope wetland system fringed the permeable alluvial fan deposits, being maintained by streamflow, precipitation and ground water recharge. A prolonged high water table is indicated by low chroma intervals interpreted as the result of gleying. A variety of redoximorphic indicators, including colour mottling and ferricrete concretions, are evidence of iron mobilization and concentration associated with a seasonally fluctuating water table. The slope wetlands were colonized periodically by Skolithos-generating organisms, most likely to have been arthropods. The widespread occurrence of redoximorphic indicators and ferricrete contrasts markedly with calcrete Vertisols in penecontemporaneous continental deposits (Lower Old Red Sandstone) of the region. It is likely that the alluvial fan-toe area was the site of a wetland depression, which maintained a high, though fluctuating, water table. In contrast the alluvial channel reaches of the surrounding drainage network were significantly better drained, with floodplains prone to wetting and drying and Vertisol palaeopedogenesis.

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Section: Trichrug Formation Distal Fan Lithofaciessupporting

confidence: 66%

Section: Trichrug Formation Distal Fan Lithofaciesmentioning

confidence: 66%

Alluvial fan and wetland interactions: evidence of seasonal slope wetlands from the Silurian of south central Wales, UK

Hillier¹,

Waters²,

Marriott

et al. 2010

Sedimentology

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“…Rare, massive, matrix-supported conglomerates may be indicative of infrequent high-density, hyperconcentrated flows that display characteristics of both non-cohesive debris flows and sheet floods (Benvenuti & Martini 2002;Hartley et al 2005). Comparable deposits to those present in facies associations B and C have been described from, for example, the Devonian Old Red Sandstone of Wales (Turnbridge 1984;Hillier & Williams 2007), the Triassic Chinle Formation in the USA (DeLuca & Eriksson 1989) and the Cretaceous of Korea (Sohn et al 1999) and are attributed to deposition on alluvial fans.…”

Section: Depositional Processes and Palaeoenvironmental Interpretationmentioning

confidence: 94%

Palaeoenvironmental analysis of Archaean siliciclastic sedimentary rocks in the west–central Jack Hills belt, Western Australia with new constraints on ages and correlations

Eriksson

Wilde

2010

JGS

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Zircons with ages between 3.05 and 4.4 Ga and hosted in conglomerates and associated sandstones in the Jack Hills belt of Western Australia have been the subject of numerous studies but none, to date, has been concerned with understanding the depositional environments of the sedimentary rocks. Intact, 250 and 320 m thick stratigraphical sections include conglomerates and sandstones that are equivalent to those at the W74 discovery site that host the ancient zircons. Facies associations are compatible with a prograding fan delta depositional setting in which alluvial fans were sourced by proximal highlands, were built directly into a lake or sea and were characterized by high gradients and high flow velocities. Locally, the succession is capped by a 20-25 m thick interval of cross-bedded quartz arenite-gritstone with a similar U-Pb detrital zircon age spectrum to the W74 discovery site, suggesting that this facies association is of comparable age and genetically related to the underlying facies associations. The quartz arenite-gritstone facies association is interpreted to record transgressive tidal reworking of the fan delta. Similar sedimentary units, including areally extensive quartz arenite successions, are widely developed elsewhere in Western Australia and on other continents, indicating that stable continental crust was widespread by 3.0 Ga.

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“…, 2005; Wright & Marriott, 2007; Hillier et al. , 2007; Hillier & Williams, 2007). The Old Red Sandstone successions have an abundance of mud that formed pelleted aggregates during pedogenesis and subsequently was eroded, transported and deposited as bedload (Wright & Marriott, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…The Ridgeway Conglomerate Formation (Hillier & Williams, 2007) was laid down in an alluvial fan and braided‐river setting. Of particular note is a sand matrix in the clast‐supported conglomerates, as well as matrix‐supported conglomerates, interbeds of mudstone and sandstone and conglomerate‐sandstone couplets.…”

Section: Introductionmentioning

confidence: 99%

Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

Davies¹,

Gibling²,

Rygel

2011

Sedimentology

108

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The Palaeozoic greening of the continents -the appearance and expansion of embryophytes (land plants) in terrestrial environments -was arguably the most fundamental Phanerozoic change to the Earth system. Thirteen case studies of Cambrian to Devonian fluvial deposits from North America and Europe are documented here to illustrate the evolution of fluvial style during this period. During the Cambro-Ordovician, prior to the advent of terrestrial vegetation, fluvial systems laid down relatively coarse sands with little mud, resulting in self-formed channels and an architecture dominated by broad sheets of trough cross-beds (sheet-braided style). Similar deposits formed across a wide range of latitudes, and passed basinward into sandy coastal deposits. From the mid Ordovician onwards, an increase in floodplain mudstone corresponds broadly with the appearance of embryophytes, which would have progressively enhanced upland weathering, mud production and floodplain storage of fines. During the Late Silurian, small heterolithic channel bodies with lateral-accretion sets provide the first evidence of meandering channels, and floodplain mudstones contain more varied palaeosols, especially calcretes which appear abundantly for the first time. By the Early Devonian, channel deposits comprise sandstone lenses (channelled-braided style), probably due to the increased bank strength and cohesion and reduced potential for sediment sorting imparted by sand-mud mixtures. Muddy coastal deposits are prominent. By the Upper Devonian, fluvial deposits commonly contain fossil trees and large mainstem meandering channels with lateralaccretion sets, indicating that rooted vegetation stabilized channels. The advent of stable floodplains with levées, crevasse splays and organic litter would have encouraged the diversification of terrestrial invertebrates, which left alluvial ichnological signatures from the Late Silurian onwards.

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The Ridgeway Conglomerate Formation of SW Wales, and its implications. The end of the Lower Old Red Sandstone?

Cited by 19 publications

References 96 publications

Alluvial fan and wetland interactions: evidence of seasonal slope wetlands from the Silurian of south central Wales, UK

Alluvial fan and wetland interactions: evidence of seasonal slope wetlands from the Silurian of south central Wales, UK

Palaeoenvironmental analysis of Archaean siliciclastic sedimentary rocks in the west–central Jack Hills belt, Western Australia with new constraints on ages and correlations

Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

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