Comments on some of Britain’s oldest microfossils

Peat, C. J.

doi:10.1144/jm.3.2.65

Cited by 18 publications

(4 citation statements)

References 15 publications

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“…The Miocene palynoflora of Anglesey is derived from black clays preserved in a complex of solution pipes contained in the Gwna Group Great Limestone (?Cambrian) (Muir et al 1979;Peat, 1984) in the foreshore area of Trwyn y Pare (Fig. 2); the palaeokarst setting of the site has already been described (Morawiecka, Slipper & Walsh, 1996).…”

Section: The Trwyn Y Pare Floramentioning

confidence: 78%

A Miocene palynoflora preserved by karstic subsidence in Anglesey and the origin of the Menaian Surface

1996

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A fossil flora of Miocene age has been preserved by karstic agencies in a solution subsidence complex developed in a large exotic block of limestone, part of the Gwna Group mélange (?Cambrian), at Trwyn y Parc, Cemaes Bay, Anglesey. The flora suggests that the Menaian Surface and the Snowdonian Mountain block were already well established landscape features by the end of the Miocene. The wider geomorphological implications of the find are briefly discussed.

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Section: The Trwyn Y Pare Floramentioning

confidence: 78%

A Miocene palynoflora preserved by karstic subsidence in Anglesey and the origin of the Menaian Surface

1996

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“…(). Subsequent reports by Peat and Diver () and Peat () noted the presence of microfossils, but the taxonomic affinities of their specimens remained open. Zhang () erected the taxon Torridoniphycus lepidus for what he considered to be a cyanobacterium (blue‐green alga) with a complex life cycle, from microfossils extracted from shales of the Aultbea Fm (Torridon Group).…”

Section: Geological Settingmentioning

confidence: 99%

Palaeoecology of a billion‐year‐old non‐marine cyanobacterium from the Torridon Group and Nonesuch Formation

Strother

Wellman

2015

Palaeontology

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A new chroococcalean cyanobacterium is described from approximately 1‐billion‐year‐old non‐marine deposits of the Torridonian Group of Scotland and the Nonesuch Formation of Michigan, USA. Individual cells of the new microfossil, Eohalothece lacustrina gen. et sp. nov., are associated with benthic microbial biofilms, but the majority of samples are recovered in palynological preparations in the form of large, apparently planktonic colonies, similar to extant species of Microcystis. In the Torridonian, Eohalothece is associated with phosphatic nodules, and we have developed a novel hypothesis linking Eohalothece to phosphate deposition in ancient freshwater settings. Extant cyanobacteria can be prolific producers of extracellular microcystins, which are non‐ribosomal polypeptide phosphatase inhibitors. Microcystins may have promoted the retention and concentration of sedimentary organic phosphate prior to mineralization of francolite and nodule formation. This has a further implication that the Torridonian lakes were nitrogen limited as the release of microcystins is enhanced under such conditions today. The abundance and wide distribution of Eohalothece lacustrina attests to the importance of cyanobacteria as oxygen‐producing photoautotrophs in lacustrine ecosystems at the time of the Mesoproterozoic–Neoproterozoic transition.

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“…Clast sizes vary from > I km to individual sand grains dispersed within the pelitic matrix. No relative age relationships are known for the different melange types, and the absolute age of the Gwna melange (although clearly pre-Arenig) remains uncertain, with a late Precambrian or early Cambrian age being most likely (Wood & Nicholls, I973;Muir et al 1979;Peat, 1984).…”

Section: The Basement On Llynmentioning

confidence: 99%

Basement–cover relationships around Aberdaron, Wales, U.K.: the fault-reactivated northwestern margin of the Welsh Basin

Gibbons

1989

Geol. Mag.

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On mainland North Wales basement rocks emerge from beneath a Lower Ordovician cover along the west side of the Llyn peninsula. The basement contains steeply dipping mylonites (Llŷn shear zone) that separate plutonic and gneissic rocks (Sarn Complex) from a melange (Gwna mélange). The western edge of the Ordovician outcrop follows the basement shear zone, and new trenching data confirm that only a faulted relationship exists between cover and basement along this northwestern extremity of the Welsh Basin. Deformation along this margin has propagated into the Arenig cover to produce southeasterly verging thrusts, asymmetric folds and northwesterly dipping cleavage. A prominent steep fault (Daron Fault) cutting the Ordovician succession follows an eastern splay of the Llŷn shear zone and again therefore records brittle reactivation of an underlying mylonite belt. The likelihood of syn-Arenig fault movements is provided by the presence of a prominent late Arenig coarse clastic unit, containing boulders of the basement mylonites, that is found only to the west of the Daron Fault. Steep basement structures such as the Llŷn shear zone, initially generated as major transcurrent faults, are interpreted as having exerted a strong control over the deposition and subsequent deformation of the Ordovician cover sequence.

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Comments on some of Britain’s oldest microfossils

Cited by 18 publications

References 15 publications

A Miocene palynoflora preserved by karstic subsidence in Anglesey and the origin of the Menaian Surface

A Miocene palynoflora preserved by karstic subsidence in Anglesey and the origin of the Menaian Surface

Palaeoecology of a billion‐year‐old non‐marine cyanobacterium from the Torridon Group and Nonesuch Formation

Basement–cover relationships around Aberdaron, Wales, U.K.: the fault-reactivated northwestern margin of the Welsh Basin

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