GCR block - Dinantian of Southern England & South Wales (DIN-S-E-WL)

Dinantian of Southern England & South Wales

Block Description

UK map showing distribution of GCR sites of GCR block DIN-S-E-WL
Distribution of GCR sites of GCR block Dinantian of Southern England & South Wales

The GCR sites selected for this GCR Block represent the British geological record of Earth history from about 354 to 327 million years ago (Ma) as represented by rocks in southern England and South Wales. This interval is the first part of the Carboniferous Period, which spans from about 354 to 292 Ma. Rocks that formed during the during Dinantian time constitute the Dinantian Subsystem, which comprises the Tournaisian and Visean series, in turn made up from the Courceyan, Chadian, Arundian, Holkerian, Asbian and Brigantian stages. In the GCR, the Dinantian Subsystem plus Pendleian and Arnsbergian stages (the lowest two stages of the overlying Silesian Subsystem) are equated with Lower Carboniferous (or Mississipian) Subsystem.

The majority of the stages are defined at stratotype sections, either in northern England, South Wales or southern Ireland, but a stratotype section for the Arnsbergian Stage has yet to be established.

Palaeoenvironment and palaeogeography

The major features controlling deposition in Britain during Early Carboniferous times owe much to structures inherited from the Caledonian Orogeny.(See CAL-STR-LD; CAL-STR-SU and CAL-STR-WL). Closure of the Iapetus Ocean had led to the development of a suture running ENE–WSW across northern England, with differing Lower Palaeozoic geological histories on either side.The Caledonian structure of England and Wales was strongly influenced by a ‘Midlands Microcraton’ in central England.To the east of this, Caledonian structures trend north-west–south-east, but to the west and north the trend is north-east–south-west.A major feature of the palaeogeography of Britain during Early Carboniferous times is the land area of the Wales–Brabant Massif, formerly known as St George’s Land, which is, at least in part, a remnant of this Midlands Microcraton.

Major collision was taking place through Central Europe during the Early Carboniferous Subperiod as a result of closure of the Rheic Ocean, but to the north of this, in Britain, extensional tectonics prevailed.An overall north–south stretching is envisaged, although east–west tension has also been suggested.In England and Wales north of the Wales–Brabant Massif, the combination of (probable) north–south extension combined with the inherited Caledonian structures led to the development of asymmetric grabens with relative subsidence partly controlled by the position of low-density granite plutons.Rifting was pulsed, with particularly active episodes in Chadian–early Arundian and in mid–late Asbian times.Significant rifting also took place during Courceyan times.

Areas undergoing slow subsidence and thus accommodating a relatively thin Lower Carboniferous succession have been variously called ‘blocks’, ‘highs’, ‘horsts’, ‘shelves’ or ‘platforms’, and the areas undergoing more rapid subsidence as ‘basins’, ‘troughs’, ‘gulfs’ or ‘lows’.

South of the Wales–Brabant Massif, the Culm Trough and the shelf area bordering it are remnants of a back-arc basin relating to northwards subduction and closure of the Rheic Ocean.In Scotland, between the Grampian Mountains to the north and the Southern Uplands to the south, a major rift, the Midland Valley, formed, controlled by movements on inherited Caledonian faults.

In late Dinantian times, uplift of source areas led to southwards progradation of a giant clastic delta complex which rapidly filled the basinal areas.At this time, active rifting largely ceased and subsidence in Namurian and Westphalian times was regional and thermally driven.

The final closure of the Rheic Ocean led to the ‘Variscan’ or ‘Hercynian Orogeny’ (see VAR-STR-SW and VAR-STR-WM) during late Westphalian and Permian times.South of the Wales–Brabant Massif, compression resulted in thrust faulting and nappe emplacement.In northern Britain, inversion of Lower Carboniferous half-graben and subsequent erosion led to the development of a Permian–Carboniferous angular unconformity.

GCR site selection

For the Dinantian stratigraphy of Britain sites were selected according to palaeogeographically defined GCR Blocks.

• Dinantian of Scotland – Midland Valley Basin

• Dinantian of northern England and North Wales – Northumberland Trough; Lake District and Alston Blocks; Stainmore Basin and Askrigg Block; Craven Basin; Derbyshire Platform, North Staffordshire Basin and the Hathern Shelf; and North Wales Shelf;

• Dinantian of southern England and South Wales – South Wales–Mendip Shelf

• Dinantian of Devon and Cornwall

Although the relatively common invertebrate fossils do not have a separate selection category in the GCR in their own right, the scientific importance of many stratigraphy sites lies in their fossil content. Therefore, some of the GCR sites are selected specifically for their fossil fauna, which facilitates stratal correlation and enables the interpretation of the environments in which the animals lived. Moreover, some sites have international significance because they have yielded fossils that are the ‘type’ material for a taxonomic group.

Palaeontology, fauna and flora

In the early 20th century the first coral–brachiopod zonation schemes for the British Lower Carboniferous sequence were established; subsequently a proliferation of biostratigraphical schemes for the Lower Carboniferous successions of north-west Europe has evolved based principally on the distribution of miospores, conodonts, foraminifera and ammonoids.

Volume Introduction

Dinantian of Southern England & South Wales

Site List

Your selection found 30 GCR sites. Sites are sorted alphabetically by country, local authority and then by site name -
CodeNameCountryLocal AuthorityGrid RefGCR Site Account
2330Avon GorgeEnglandBristol, City ofST560743Not available
2792Edgehill Sand QuarryEnglandGloucestershireSO661168Not available
2790Scully Grove QuarryEnglandGloucestershireSO658187Not available
2791Stenders QuarryEnglandGloucestershireSO659183Not available
1833Barnhill QuarryEnglandNorth and North East Somerset, South GloucestershireST725828Not available
1834Burrington CombeEnglandNorth and North East Somerset, South GloucestershireST476584Not available
1831Spring CoveEnglandNorth and North East Somerset, South GloucestershireST310625Not available
2788Cook`s Wood QuarryEnglandSomersetST669479Not available
2789Maesbury Railway CuttingEnglandSomersetST606475Not available
2787Vallis ValeEnglandSomersetST755490Not available
2886Flat Holm, Bristol ChannelWalesCARDIFF AND VALE OF GLAMORGANST220647Not available
1756Tongwynlais Road SectionWalesCARDIFF AND VALE OF GLAMORGANST129825Not available
1754Brofiscin QuarryWalesCENTRAL VALLEYSST070813Not available
1755Long Wall QuarryWalesCENTRAL VALLEYSST048813Not available
1776Odynau Tyle`r BontWalesCENTRAL VALLEYSSO063113Not available
1753DanygraigWalesGWENT VALLEYSST234908Not available
1752Clydach Halt Lime WorksWalesMONMOUTHSHIRE AND NEWPORTSO234128Not available
1749GilwernWalesMONMOUTHSHIRE AND NEWPORTSO247126Not available
1751Llanelli QuarryWalesMONMOUTHSHIRE AND NEWPORTSO225125Not available
1777Baltic QuarryWalesPOWYSSO064117Not available
3341Blaen Onneu QuarryWalesPOWYSSO155169Not available
1748Cwar yr Ystrad & HendreWalesPOWYSSO085142Not available
1759Blucks Pool - Bullslaughter BayWalesSOUTH WEST WALESSR890976Not available
1775Tenby CliffsWalesSOUTH WEST WALESSN135004Not available
1780Bracelet BayWalesSWANSEASS629871Not available
1783Caswell BayWalesSWANSEASS594877Not available
1778Ilston QuarryWalesSWANSEASS555906Not available
1781Oystermouth Old QuarryWalesSWANSEASS615883Not available
1782Pwll Du HeadWalesSWANSEASS568864Not available
1779Three Cliffs BayWalesSWANSEASS529877Not available
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