Mass collapse and resedimentation on a Brigantian–Early Namurian platform margin, Halkyn–Mold area, North Wales, UK

2021 ◽  
Author(s):  
Anthony Kirkham
Keyword(s):  
North Wales ◽  
Platform Margin ◽  
Area North

scholarly journals Longvillian Shelly Faunas From the Dolwyddelan Area, North Wales

1969 ◽  
Vol 106 (6) ◽  
pp. 603-606 ◽  
Author(s):  
M. Romano ◽  
J. N. Diggens
Keyword(s):  
North Wales ◽  
Area North

scholarly journals Controls on dolomitization in extensional basins: An example from the Derbyshire Platform, U.K.

2020 ◽  
Vol 90 (9) ◽  
pp. 1156-1174 ◽  
Author(s):  
Catherine Breislin ◽  
Stephen Crowley ◽  
Vanessa J. Banks ◽  
Jim D. Marshall ◽  
Ian L. Millar ◽  
...  
Keyword(s):  
Geothermal Gradient ◽  
Volcanic Complex ◽  
Carbonate Platforms ◽  
Rift Basins ◽  
Southern Margin ◽  
North Wales ◽  
Platform Drowning ◽  
Platform Margin ◽  
Platform Carbonates ◽  
Planar Fabric

ABSTRACT Fault-controlled dolomitization has been documented in Lower Carboniferous (Viséan) platform carbonates at various localities in the Pennine Basin and North Wales. The largest of these dolomite bodies (approx. 60 km2) occurs on the Derbyshire Platform, on the southern margin of the Pennine Basin. This study tests the hypothesis that dolomitization occurred at this locality during deposition, platform drowning, and the earliest stages of burial, coincident with the transition from a late syn-rift to post-rift regime. It also assesses the importance of syn-rift volcanism on dolomitization. Planar, fabric-retentive dolomite with single-phase (i.e., low temperature) fluid inclusions occurs along NW–SE and E–W oriented faults, and in platform margin facies and in proximity to the Masson Hill Volcanic Complex. Oxygen isotope data are consistent with dolomitization from seawater, but slightly depleted δ13C values reflect mixing with magmatic fluids. Volcanic activity is likely to have produced a thermal drive for fluid circulation on the platform margin, and post-depositional alteration of basalts by CO2-rich fluids could have led to alteration of olivine and release of magnesium to convecting seawater. Consequently, the large volume of dolostone on the southern margin of the Derbyshire Platform is attributed to the increased geothermal gradient and a localized increase in the Mg/Ca ratio of dolomitizing fluids at this locality, compared to elsewhere in the Pennine Basin. The results suggest that syn-rift carbonate platforms in volcanically active areas of rift basins have a greater potential for dolomitization from seawater than non-volcanic platforms in the same basin.

Cruziana: A stratigraphically useful trace fossil

1968 ◽  
Vol 105 (4) ◽  
pp. 360-364 ◽  
Author(s):  
T. P. Crimes
Keyword(s):  
Trace Fossil ◽  
British Isles ◽  
Upper Cambrian ◽  
North Wales ◽  
Lower Ordovician ◽  
New Localities ◽  
Area North ◽  
First Time

SUMMARYCruziana semiplicata (Salter) is recorded, generally in abundance, from previously known and new localities within Upper Cambrian (Ffestiniog) sediments in Snowdonia, and the Portmadoc area, North Wales. C. furcifera (D'Orb) is recorded for the first time in the British Isles from four localities within Lower Ordovician (Arenig) sediments on St. Tudwal's Peninsula, North Wales.It is shown that each of these species is of limited but different range, and it is suggested that they could be useful in distinguishing between otherwise unfossiliferous Cambrian and Ordovician strata.

scholarly journals The role of the clinical tutor – a personal experience

1990 ◽  
Vol 14 (3) ◽  
pp. 164-165
Author(s):  
Jeffrey R. Jones
Keyword(s):  
Medical School ◽  
Rural Area ◽  
Royal College ◽  
Personal Experience ◽  
North Wales ◽  
Area North ◽  
The University

The role of the clinical tutor may differ from that set out in the helpful guidelines given by the Royal College of Psychiatrists. It may differ depending on the setting of the training for instance. I was made clinical tutor some three and a half years ago for a large, mainly rural area – North Wales. The area does not have its own medical school, but is associated with the University of Wales College of Medicine, at Cardiff, some 150 miles away.

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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