The stratigraphy and structure of the Whithorn area of Wigtownshire, Scotland

Rust, Brian R.

doi:10.1144/sjg01020101

Cited by 57 publications

(39 citation statements)

References 23 publications

(29 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The unit is a turbidite sequence consisting of fine-grained flaggy sandstone, siltstone, and mudstone greywacke and red mudstone interbeds (Lapworth 1889;Peach & Home 1899;Warren 1964). The age is uncertain because of the general lack of fossils and it is currently regarded as Upper Llandovery (Rust 1965a;Leggett et al 1979), Wenlock (Warren 1964), or Ludlow (Clarkson et al 1975.…”

Section: Stratigraphy and Sedimentologymentioning

confidence: 99%

Trace fossils from Lower Palaeozoic ocean-floor sediments of the Southern Uplands of Scotland

Benton

1982

Transactions of the Royal Society of Edinburgh: Earth Sciences

View full text Add to dashboard Cite

The Ordovician and Silurian rocks of the Southern Uplands of Scotland have been interpreted as sediments deposited on the northern margin of the Iapetus Ocean. Trace fossils are abundant at many localities in ocean-floor turbidites and mudstones that usually lack all other evidence of life. Twelve ichnogenera are present, and they are mainly meandering locomotion and feeding trails and burrow networks: Dictyodora, Caridolites, Helminthoida, Neonereites, Nereites, Protovirgularia, Gordia, Megagrapton, Paleodictyon, Chondrites, Plano-lites and Skolithos. The trace fossils occur in at least five distinct assemblages and the composition of these was probably controlled by the frequency and nature of the turbidity currents, and possibly by the oxygen content of the mudstones. Where turbidity currents were weak, abundant Dictyodora, together with Caridolites, Neonereites, Nereites, Protovirgularia and Gordia occur in various combinations. Where currents were stronger, traces such as Gordia, Paleodictyon and Megagrapton may be exhumed and cast on turbidite soles, and the sand may contain Skolithos. The ‘deep-sea’ Nereites trace fossil facies is divisible into several assemblages, presumably environmentally controlled.

show abstract

Section: Stratigraphy and Sedimentologymentioning

confidence: 99%

Trace fossils from Lower Palaeozoic ocean-floor sediments of the Southern Uplands of Scotland

Benton

1982

Transactions of the Royal Society of Edinburgh: Earth Sciences

View full text Add to dashboard Cite

show abstract

“…It is probable that all movement episodes which affected the Whithorn region (Rust 1965a) are represented in the Gatehouse area. The correlation has, however, some imperfections, and to emphasise these discrepancies it appears desirable to adopt a phase terminology having a measure of flexibility.…”

Section: Foldingmentioning

confidence: 99%

Structural history of the Silurian rocks of the coast west of Gatehouse, Kirkcudbrightshire

Weir

1968

SJG

View full text Add to dashboard Cite

Synopsis The rocks exposed in the coastal sections between Gatehouse and Creetown, Kirkcudbrightshire, are considered to belong to the Hawick Rocks (Upper Valentian), and have been affected by five main episodes of deformation, three of which are of Caledonian age. The first phase produced E.N.E.-W.S.W. similar folds and associated tensional strike faults, forming the structural basis of the area and determining the outcrop distribution. During the second phase these folds were modified, and a new set of concentric folds, comparable in strike but with axial surfaces dipping at around 45° S.S.E., was generated, along with a conjugate set of wrench faults. Folds of the third phase have E.-W. axes and steep eastward plunges. The three phases are equated respectively with F 1 F 2 and F 3 of the Whithorn area ( Rust 1965a ). The fourth phase gave rise to folds with near-horizontal axial planes, and frequently developed as minor thrusts, and the final deformation gave rise to dextral kink-bands trending N.-S. The two last are correlated with F 4 and F 5 of Whithorn, to which Hercynian and Alpine dates are provisionally allocated. A swarm of dykes was emplaced between the first and second phases, and further dykes were intruded after the second phase.

show abstract

“…Subsequent, predominantly structural studies (e.g. Rust 1965;Weir 1968;Anderson and Cameron 1979) confirmed these observations and showed that some dykes were involved in folding and faulting. However, none of these papers provided chemical or modern petrographical data.…”

Section: Introductionmentioning

confidence: 83%

“…The country rocks were folded and cleaved by one main phase of deformation (DJ which all of the dykes post-date. Planar fabrics are frequently observed in porphyrite/porphyry dykes and have been interpreted in two ways by previous workers who related them to the regional country-rock cleavage, suggesting pre-D, emplacement (Reynolds 1931;Rust 1965), or to shearing during emplacement (Blyth 1949). However the fabric in the dykes is only subparallel to the regional cleavage in bed-parallel intrusions.…”

Section: Nomenclature Scheme For Southern Uplands Dykesmentioning

confidence: 99%

Late Caledonian dyke‐swarms in Southern Scotland: New field, petrological and geochemical data for the Wigtown Peninsula, Galloway

1986

View full text Add to dashboard Cite

Several hundred, dominantly NE-trending dykes invade Silurian flysch sediments of the Wigtown Peninsula. The most basic dykes are K-rich biotite-lamprophyres, hornblende-lamprophyres and appinites ('diorites' of previous maps). More acidic (qz and cm normative) dykes include restricted andesitic compositions ('porphyritcs', c. 57 per cent SiO,) and a continuum from dacitic to rhyolitic compositions ('acid porphyrites' and 'porphyries', c. 63-71 per cent SiO,). The relative abundance of basic to intermediate -k acidic dykes, based on examination of 180 thin sections and 70 new whole-rock analyses, is approximately 7 : 1. The biotite-and hornblende-lamprophyres are distinct in chemistry and distribution, biotite-lamprophyres being confined to the south of the Peninsula. Neither type has any compositional equivalent among the plutonic rocks of the area. Porphyrite and porphyry dykes do not represent simple lamprophyre fractionates, but may be derived from at least two (intermediate and acidic) parent magmas, which may represent crustally-contaminated lamprophyre or entirely separate crustal melts. Emplacement of all dyke compositions was apparently episodic through Wenlock to early Devonian times (c. . Early dykes post-date the main deformation (D,) but predate minor (D,) folding, both D, and D, being related to thrusting. On the current accretionary model for the Southern Uplands, this implies that dyke emplacement commenced before the end of accretion in a compressional tectonic regime-scarcely consistent with the moderate (up to 6 per cent) crustal extension represented by the dykes. The geochemistry of the lamprophyres requires a deep mantle origin several hundred kilometres behind any subduction zone. This suggests that the 'Iapetus suture', at the time of dyke emplacement, was much farther south than its currently inferred position and places the Southern Uplands in a back-arc situation.

show abstract

The stratigraphy and structure of the Whithorn area of Wigtownshire, Scotland

Cited by 57 publications

References 23 publications

Trace fossils from Lower Palaeozoic ocean-floor sediments of the Southern Uplands of Scotland

Trace fossils from Lower Palaeozoic ocean-floor sediments of the Southern Uplands of Scotland

Structural history of the Silurian rocks of the coast west of Gatehouse, Kirkcudbrightshire

Late Caledonian dyke‐swarms in Southern Scotland: New field, petrological and geochemical data for the Wigtown Peninsula, Galloway

Contact Info

Product

Resources

About