Recycled acritarchs as provenance indicators: implications for Caledonian terrane reconstruction

McCaffrey, William D.; Barron, Hugh F.; Molyneux, Stewart G.; Kneller, Ben

doi:10.1017/s0016756800019531

Cited by 19 publications

(6 citation statements)

References 33 publications

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“…(3) Emergent thrust sheets shed sediment into the foreland basin from mid-Ludlow time. Turbidite sedimentation in the Ludlow was mainly sandy in the Coniston Group followed by mixed sand, silt and mud in the Bannisdale Formation, all with dominantly southwestward palaeoflow, and inferred Scandian provenance (McCaffrey et al 1992;McCaffrey, 1994). Lack of marginal facies suggests that these units were continuous across the central Lake District, an idea supported by the predominance of locally derived Silurian clasts in the Devonian Mell Fell conglomerate (Capewell, 1955).…”

Section: B Critique Of the Flexural Model In Northwest Englandmentioning

confidence: 97%

The lost Lower Old Red Sandstone of England and Wales: a record of post-Iapetan flexure or Early Devonian transtension?

Soper

Woodcock

2003

Geol. Mag.

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Illite crystallinity data from the Silurian slate belts of England and Wales indicate anchizone to low epizone metamorphism during the Acadian deformation in late Early Devonian time. This metamorphic grade implies a substantial overburden, now eroded, of Lower Devonian non-marine sediments of the Old Red Sandstone (ORS) magnafacies. A minimum 3.5 km pre-tectonic thickness of ‘lost’ ORS is estimated in the southern Lake District and comparable thicknesses in North Wales and East Anglia. Tectonically driven subsidence of the underlying Avalonian crust is required to accommodate such thicknesses of non-marine sediment. One proposed mechanism is flexure of the Avalonian footwall during convergence that continued from Iapetus closure in the Silurian until Acadian cleavage formation in the Emsian. The evidence for this model in the critical area of northwest England is reviewed and found to be unconvincing. An alternative model is developed following a recent suggestion that the Early Devonian was a period not of continued convergence but of orogen-wide sinistral transtension. Transtensional accommodation of the lost ORS is evidenced by Early Devonian extensional faults, by synchronous lamprophyric magmatism, and by compatibility with previously diagnosed sediment provenance patterns. A summary of Siluro-Devonian tectonostratigraphy for Britain south of the Highland Border emphasizes that, unlike the Scottish Highlands, this area was not affected by the Scandian Orogeny, but was by the Acadian. An important period of sinistral transtension in the Early Devonian (c.420–400 Ma) was common to both regions. This was a time of high heat flow, lamprophyric and more evolved magmatism, and major southward sediment transport, involving mainly recycled metamorphic detritus from the Highlands and from contemporaneous volcanicity. Old Red Sandstone, deposited in coalescing transtensional basins over much of Britain from the Midland Valley to the Welsh Borders, was largely removed and recycled southward during Acadian inversion.

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Section: B Critique Of the Flexural Model In Northwest Englandmentioning

confidence: 97%

The lost Lower Old Red Sandstone of England and Wales: a record of post-Iapetan flexure or Early Devonian transtension?

Soper

Woodcock

2003

Geol. Mag.

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“…Recycled acritarchs are common in the Palaeozoic (McCaffrey et al 1992). Thomas (1978b) recorded them in 2 LLF and 9 MBF samples.…”

Section: Ages Of Source Rocksmentioning

confidence: 99%

Enigma variations: the stratigraphy, provenance, palaeoseismicity and depositional history of the Lower Old Red Sandstone Cosheston Group, south Pembrokeshire, Wales

Thomas¹,

Williams

Morrissey

et al. 2006

Geol. J.

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“…Vanguestaine (1979), Roche et al (1986) and Steemans (1989) described reworking in the Lower Devonian of the Belgian Ardennes. McCaffrey et al (1992) discussed the palaeogeographical potential of recycled acritarchs in Silurian strata of the British Isles including southeast Ireland. Other examples are known in the Belgian Brabant Massif where (Keiem BH9, 36E138 borehole) both Cambrian and Ordovician acritarchs are reworked in Silurian strata (M. Vanguestaine, unpublished work).…”

Section: Palynology Of the Moanbrack Formationmentioning

confidence: 99%

“…Uplift and erosion of part of a basin or submarine canyons in shelf sequences are possible explanations for such phenomena. Detailed mechanisms of reworking are, however, poorly known (see, however, discussion in McCaffrey et al 1992). …”

Section: Palynology Of the Moanbrack Formationmentioning

confidence: 99%

An Ordovician age for the Muggort's Bay Lower Palaeozoic inlier, County Waterford, Ireland—the southernmost exposure of the Irish Caledonides

Bruck

Vanguestaine

2005

Geol. J.

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The most southerly exposed Lower Palaeozoic strata in Ireland occur on the southwest coast of County Waterford along a 2.5 km long coastal section at Muggort's Bay where they are surrounded by Devonian rocks. Five formations can be distinguished which, in ascending order, are: the Ballycurreen, Carrickbrean, Rathnameenagh, Moanbrack and Killinoorin formations. The total thickness of the succession is over 1800 m. No macrofossils are present, but the lithologies are largely fine-grained turbidites and subordinate volcanic rocks which closely resemble the Ribband Group seen elsewhere in southeast Ireland and have previously therefore been classified with it. Palynological analysis was undertaken on 25 samples collected from Muggort's Bay, of which eight were productive. Diagnostic microfossils, comprising acritarchs, chitinozoans and scolecodonts, indicate an Early to Middle Ordovician age for both the Rathnameenagh and the Moanbrack formations. These ages confirm that the strata are part of the Ribband Group which elsewhere has been biostratigraphically dated as ranging from Mid-Cambrian to Mid-Ordovician. Reworked mid-Middle Cambrian acritarchs occur in the Moanbrack Formation and reworked late Middle to early Late Cambrian acritarchs in the Rathnameenagh Formation. Despite generally poor preservation of the organic matter, some 20 acritarch species have been distinguished. Among these, three species belong to the herein revised genus Retisphaeridium for which an emended diagnosis is proposed together with two new combinations, Retisphaeridium capsulatum (Jankauskas, 1976) Vanguestaine nov. comb. and Retisphaeridium pusillum (Moczydlowska, 1998) Vanguestaine nov. comb.

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Recycled acritarchs as provenance indicators: implications for Caledonian terrane reconstruction

Cited by 19 publications

References 33 publications

The lost Lower Old Red Sandstone of England and Wales: a record of post-Iapetan flexure or Early Devonian transtension?

The lost Lower Old Red Sandstone of England and Wales: a record of post-Iapetan flexure or Early Devonian transtension?

Enigma variations: the stratigraphy, provenance, palaeoseismicity and depositional history of the Lower Old Red Sandstone Cosheston Group, south Pembrokeshire, Wales

An Ordovician age for the Muggort's Bay Lower Palaeozoic inlier, County Waterford, Ireland—the southernmost exposure of the Irish Caledonides

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