Enigmatic boulders and syn-sedimentary faulting in the Carboniferous Limestone of the Isle of Man

Quirk, David G.; Ford, Trevor D.; King, James A.; Roberts, I. L.; Postance, R. B.; O'Dell, I.

doi:10.1144/pygs.48.1.99

Cited by 8 publications

(3 citation statements)

References 6 publications

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“…It consists of shallow water grainstones and packstones that pass laterally and upwards into poorly stratified basinal calcareous mudrocks of the Bowland Shale Formation. At Poyllvaaish (SC 246675), the Bowland Shale Formation contains intercalated thin to medium bedded calciturbidites and debrites, plus ‘olistoliths’ of Waulsortian‐type boundstone that are interpreted either to have been derived from gravitational collapse of an up‐dip Balladoole platform margin (Dickson et al ., ), or from more localized syn‐sedimentary faulting and slumping (Quirk et al ., ). An in situ Waulsortian‐type mound is exposed in the walls of Cross Welkin Hill Quarry and is broadly similar in facies to coeval platform‐edge bioherms of Ireland, North Wales and northern England (e.g.…”

Section: Geological Contextmentioning

confidence: 97%

Origin, characteristics and distribution of fault‐related and fracture‐related dolomitization: Insights from Mississippian carbonates, Isle of Man

et al. 2014

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Viséan limestones on the Isle of Man host numerous examples of fault‐controlled and fracture‐controlled dolomitization, which have been investigated to determine their macro‐scale to micro‐scale characteristics, geofluid origin, timing and relation to basin evolution. Geobodies composed of fabric destructive, ferroan, non‐planar dolomite range from several centimetres to >300 m wide and tens to hundreds of metres long parallel to faults and/or fractures; they have sharply defined margins, cross‐cut stratigraphy and locally finger out along beds or bed boundaries for tens of metres. Larger geobodies accompany NNE–SSW extensional faults with substantial breccia zones. One of these bodies hosts a sphalerite‐rich breccia deposit cemented by dolomite. Saddle dolomite lines or fills vugs and fractures within dolomite geobodies, and is a minor late diagenetic phase in undolomitized limestones. Replacive dolomite has low matrix porosity owing to non‐planar texture and associated cementation, and there is no evidence for subsequent leaching. Three dolomite stages are discriminated by texture, cathodoluminescence petrography and electron microscopy. Disseminated ‘Dolomite 1’ is substantially replaced and may be residual early diagenetic dolomite. Pervasive ‘Dolomite 2’ and ‘Dolomite 3’ have overlapping carbon–oxygen–strontium isotopic and fluid‐inclusion characteristics that indicate precipitation from allochthonous, high‐temperature (98 to 223°C) and high‐salinity (15 to 24 wt% NaCl eq.) brines. These variably equilibrated with host limestones and mixed with resident pore fluids. Overlying mudrocks formed a seal for ascending fluids. Integration of data from the mineral deposit suggests that fault‐fracture systems tapped different deep‐seated fluid reservoirs at different temperatures, and implies fluid interactions with both metamorphic basement and sedimentary cover in large‐scale circulation systems. This phenomenon probably took place during Mesozoic rifting, although an earlier event at the end of the Early Carboniferous cannot be discounted. In either case, a transient heat flow anomaly, previously unrecognized in the Irish Sea region, may be required to account for the hottest fluids.

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Section: Geological Contextmentioning

confidence: 97%

Origin, characteristics and distribution of fault‐related and fracture‐related dolomitization: Insights from Mississippian carbonates, Isle of Man

et al. 2014

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“…These occur in the south of the island and are believed to range in age from Arundian to Brigantian (Dickson et al, 1987). Shales within this succession are often rich in terrestrial plant material and brackish water bivalves with marine goniatites preserved at some levels (Quirk et al, 1990). Porosityfilling bitumen has been recorded in dark limestones within this Group.…”

Section: Carboniferous Lithostratigraphy Onshore Isle Of Manmentioning

confidence: 95%

Palynological and Geochemical Analysis of Carboniferous Borehole and Outcrop Samples From the Isle of Man

Racey

Goodall²,

Quirk³

1999

Journal of Petroleum Geology

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Palynological and geochemical analyses were performed on Namurian (mid‐Carboniferous) samples from the Ballavaarkish and Shellag Point boreholes from the north of the Isle of Man, and on Dinantian/Namurian outcrop samples from Black Marble Quarry in the south of the island. The boreholes yielded a rich and diverse (over 60 species) Namurian B‐C (Kinderscoutian‐Yeadonian) palynomorph assemblage equivalent to the KV/FR Zones of Clayton et al. (1977). Reworked Brigantian‐Namurian A palynomorphs of the NC/TK Zones were recorded in the Shellag Point borehole. Offshore seismic data indicates a period of major fault activity in the early Namurian which may support this concept of early Namurian reworking. Amorphous organic matter indicating anoxic/dysoxic depositional conditions together with prasinophyte algae and goniatites suggesting a marine environment were recorded in the Shellag Point borehole. Vitrinite reflectance and spore colouration measurements coupled with Tmax data from Rock‐Eval pyrolysis indicate that the Namurian shales from the Shellag Point borehole are currently in the oil window. Rock‐Eval data and kerogen analyses indicate that these shales represent moderate to good gas‐prone source rocks which have yet to attain full maturity. The Namurian samples from Ballavaarkish are mainly in the oil window or late mature zone and have poor gas potential. Extract chromatography indicates a relatively mature product and the possible onset of hydrocarbon biodegradation, particularly in the Ballavaarkish borehole samples. Outcrop samples from near the top of the succession at Black Marble Quarry underwent thermal alteration as a result of dyke intrusion and subsequent volcanism. Although previously believed to be Brigantian (end‐Dinantian) in age based on goniatites, corals and conodonts, the samples have produced a sparse palynological assemblage indicating an apparent age no older than Namurian. The samples are late‐ to post‐mature in terms of hydrocarbon generation and have no remaining source potential. The results indicate that where Namurian sediments are preserved beneath the base‐Permian unconformity, for example in the Solway Basin, hydrocarbons are likely to have been generated.

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“…Red beds of the Langness Conglomerate Formation at the base of the Carboniferous succession are unconformable on the Manx Group, whilst basaltic flows, pillow lavas and volcaniclastic deposits of the Scarlett Volcanic Formation are intercalated in the limestones between Scarlett Point and Poyllvaaish (Ford et al , 2001). In most places, the succession is flat‐lying or gently tilted, although near Poyllvaaish the beds were folded and otherwise disturbed before lithification (Dickson et al , 1987; Quirk et al , 1990). In several areas, it is shown below that the limestones have also been gently folded, locally cleaved and subjected to stylolitic pressure solution processes.…”

Section: Introductionmentioning

confidence: 99%

Tectonic structures in the Peel Sandstones and Carboniferous limestone, Isle of Man

Fitches¹

2010

Geological Journal

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On the Isle of Man, the Early Devonian Peel Sandstones and Early Carboniferous limestones have been deformed in places by folds, cleavage and other structures. The structures in the Peel Sandstones have been attributed to pre‐lithification deformation associated with slumping of the red beds. Here, they are re‐interpreted to be products of post‐lithification deformation, inferred from small‐scale structures and fabrics, which took place in a localized thrust zone. Compression was approximately NW–SE and translation towards the SE. That deformation may have also produced some of the late structures in the Lower Palaeozoic rocks of the island. The minimum age of these post‐Early Devonian structures is unknown but is probably pre‐Carboniferous: they may represent the mid‐Devonian Acadian deformation. The Carboniferous succession is folded in places and contains stylolites and stylolitic cleavage. A stress regime with E–W to WNW–ESE compression is inferred. These structures have orientations and morphologies shown to resemble those in neighbouring parts of southern Britain, where they are attributed mainly to mid‐ to late‐Carboniferous Variscan events. Alternatively, some or all of them might be products of late Mesozoic and Tertiary tectonics recognized elsewhere in the region. Copyright © 2010 John Wiley & Sons, Ltd.

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Enigmatic boulders and syn-sedimentary faulting in the Carboniferous Limestone of the Isle of Man

Cited by 8 publications

References 6 publications

Origin, characteristics and distribution of fault‐related and fracture‐related dolomitization: Insights from Mississippian carbonates, Isle of Man

Origin, characteristics and distribution of fault‐related and fracture‐related dolomitization: Insights from Mississippian carbonates, Isle of Man

Palynological and Geochemical Analysis of Carboniferous Borehole and Outcrop Samples From the Isle of Man

Tectonic structures in the Peel Sandstones and Carboniferous limestone, Isle of Man

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