Next Meeting

Saturday 23rd January 2010, Saturday 27^th February 2010, 2pm: University of Leeds, Weetwood Hall: Deep Water Sedimentology

Summary programme and Abstracts:

Dr Chris Jackson (Imperial College, London): Submarine slope morphology as a control on the development of sand-rich turbidite depositional systems: 3D seismic analysis of the Kyrre Fm (Upper Cretaceous), 
Måløy Slope, offshore Norway

Three-dimensional seismic and well data are integrated to investigate the geometry and controls on a series of sand-rich slope systems in the Kyrre Fm (Upper Cretaceous) on the Måløy Slope, offshore Norway. Norway. Slope systems were fed by sediments eroded from mainland Norway to the east, and transported across a relatively narrow shelf into four canyons developed at the shelf-edge. These canyons were not formed through erosional or mass-wasting processes during the Late Cretaceous, but represent a series of underfilled canyons developed during an earlier, Late Jurassic erosional period. Channels, which are commonly arranged into laterally- or vertically-stacked channel complexes, were fed sediment through the shelf-edge canyons and may be associated downslope with small terminal fans. The canyons and their associated depositional systems were not active synchronously, with a clear southward migration of the active depositional systems. On the slope, syn-depositional topography was formed via; (i) differential compaction of mudstone-rich strata across underlying Late Jurassic canyons which resulted in the a series of E-W-trending structural lows; and (ii) differential compaction of mudstone-rich strata across the underlying Upper Jurassic fault blocks which resulted in N-W-trending structural highs. Both of these features had a variable influence on the incision, fill and overall spatial distribution of slope channels/channel complexes and associated fans. A large fan which overlies the shelf-edge canyons and associated downslope depositional systems represents the final depositional unit within the study area. The fan effectively ‘seals’ the underlying shelf-edge canyons, suggesting it was not supplied by sediment routed through the canyons. The results of this study support previous studies which indicate that the shelf-edge canyons may be the first-order control on the location of sand-rich, turbidite-fed depositional systems on submarine slopes. Furthermore, this study demonstrates that differential compaction may be a key control on slope morphology in submarine settings, and the associated topography can markedly influence depositional patterns.

Dr David Hodgson (University of Liverpool): Relative Timing Of External And Internal Submarine Levee Construction And The Implication For Submarine Fan Growth: insights from the Karoo Basin, South Africa.

The initial filling of a high latitude proto-foreland basin during an icehouse climate is recorded in a well-exposed 1.3 km thick basin-floor to shelf-edge succession of late Permian siliciclastic deposits in the Laingsburg depocentre of the SW Karoo basin, South Africa,. Uniformly fine-grained sandstones were derived from far-field granitic sources (Patagonia?), although the coeval staging and delivery systems (fluvial and shelfal) are not preserved. Initial mud-prone basin floor turbidites of the Vischkuil Formation contain three regionally developed zones of soft sediment deformation related to emplacement of major debris-flows that mark the initiation of a major sand delivery system. The overlying 300 m thick sand-prone basin floor fan system (Fan A) and 150 m thick base-of-slope channel/levee system (Unit B) are divisible into four composite sequences that show long term forward stepping, aggradation and backstepping stacking patterns, followed by basinwide pelagic mud deposition.

The overlying 500 m thick mud-dominated submarine slope succession is characterized by 60 – 120 m thick sand-prone to heterolithic packages that show abrupt lateral and down-dip changes in thickness and lithofacies, which are separated by extensive 30 – 70 m thick claystone packages. On the largest scale the slope stratigraphy is defined by two major cycles, each comprising three composite sequences of repeating architectural style. Each composite sequence comprises three sequences. The lower cycle comprises lithostratigraphic Units B/C, C and D while the upper cycle includes Units E/F, E and F. In each case a sandy basal sequence is dominated by intraslope lobe deposits (Units B/C and E/F). The second composite sequence in each cycle (Unit C and Unit E) is characterized by slope channel-levee complexes that feed lobes down dip. The uppermost composite sequence in each cycle (Units D and F) comprises deeply entrenched slope valley/canyon systems. Although complicated in detail, the deepwater succession shows a consistent hierarchical order, enabling prediction of temporal changes in architectural style within each composite sequence. This stratigraphic organisation is interpreted as due to high magnitude/high frequency glacial-eustatic sea level changes during a tectonically quiescent pre-foreland basin period. Architectural style is similar at individual sequence scale in comparable positions in each major cycle, but intrinsic controls such as along-strike changes in sequence expression as a function of shelf edge delivery system and variable substrate compaction complicate the resultant architecture.

Prof Bill McCaffrey (University of Leeds): Controls on submarine channel levee development.

Submarine channel levee systems arise and develop due to complex feedbacks between turbidity currents and confining bathymetry. In particular, because the flow can be lost overbank, there must be a link between the flow transmitted downstream from any particular point and the evolution of the geometric form of the levee. Consideration of aspects of this complex system can potentially give insights into: auto vs. allo-cyclic controls on channel development and avulsion; monotonic evolution of flow properties within the channel; topological approaches to channel pattern development, such as avulsion node migration directions and inundation area analysis; bed thickness distribution patterns with the levee, and in channel-fed lobes. The implications for the interpretation of architecture development will be explored, together with the implied limits on interpretation.

Dr Ian Kane (University of Leeds): Aspects of the sedimentology and architecture of the Pendle Grit and Hind Sandstone, Craven Basin, UK.

Lateral tilting is a common deformation style in extensional basins, its influence on subaerial channels is, to a degree, understood, and may be significant, controlling the style of channel development and the resultant sand-body architecture. Growth faulting and lateral tilting in turbidite channel systems have been demonstrated from 3D seismic, but the resultant architecture of channels within these settings has not yet been documented. In the Carboniferous of northern England, a sand-rich slope channel, developed within a basin undergoing late-stage extension, underwent progressive and unidirectional migration towards a topographic low on a laterally tilting block. The resultant sandstone body is wedge shaped in cross section, and comprised dominantly of sigmoidal lateral accretion deposits. The channel returned to an axial course before undergoing lateral migration in the same direction, creating a multistorey, multilateral channel sandstone body. The repeated unidirectional migration combined with evidence of syn-depositional deformation suggests that active tectonism strongly influenced channel evolution and deposition. A model of submarine channel evolution in extensional basins is presented; in systems where large displacements occur, the channel system may avulse, creating isolated sand ribbons which are connected updip; where the lateral dip is always more influential than the regional dip, the system may pond in the hanging-wall syncline. The model is compared to a subsurface channel within the Pliocene of the Nile Delta slope, which was influenced by syndepositional fault movement; application of the outcrop-derived model allows some simple architectural interpretations to be made.

Continuing Professional Development: This meeting counts as 2 hours of Continuous Professional Development under the Geology Society CPD Scheme.

Draft Summary Programme for the rest of 2010

Indoor Meetings

Saturday 27th March British Geological Survey, Keyworth, Notts.: Planning for Climate Change

October (date to be confirmed: either Saturday 23rd or Saturday 30th), University of Hull: Modern Geological Techniques (Joint Meeting with the Hull Geological Society)

28th November University of Leeds Weetwood Hall: AGM, Presidential Address Part 2, President's Reception Buffet & Speeches

Field Meetings

8th or 9th May: Yorkshire Geology Month excursion to Ingleborough, led by David Turner

12-13th June: Weekend field meeting in Teesdale: new ideas on mineralisation in Teesdale, led by Brian Young

July (date to be confimed): Ironstone mining in North Yorkshire, led by Simon Price Jon Ford & Rebecca Levell

August: Wadsley Fossil Forest, Sheffield, led by Ken Dorning

Proceedings now fully digitised from vol. 1 (1839) to vol. 58 (2008) with free online access to individual YGS members

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Stewart Molyneux
Principal Editor, Proceedings of the Yorkshire Geological Society

Latest part of Proceedings of Yorkshire Geological Society (vol. 57 pts. 3-4, November 2009) now published: Contents and Abstracts

Cover illustration: Chadian (Lower Carboniferous) ammonoid Fascipericyclus fasciculatus (McCoy) from Beeston Tor, southern Peak District (Staffordshire) (British Geological Survey Colln.) (See Tilsley & Korn, this part)

P. Vincent and A. S. Smith: A redescription of Plesiosaurus propinquus Tate & Blake, 1876 (Reptilia, Plesiosauria), from the Lower Jurassic (Toarcian) of Yorkshire, England (pp. 133-142)

SUMMARY: The type specimen (WM 851.S, skull and post-cranial skeleton) of Plesiosaurus propinquus Tate & Blake, 1876, from the Toarcian (Upper Lias, Lower Jurassic) of Yorkshire, is re-examined. New observations permit a detailed understanding of the cranial anatomy of this specimen and hence its taxonomic affinity. The few differences between Plesiosaurus propinquus and Rhomaleosaurus zetlandicus cannot be considered diagnostic. Consequently, Plesiosaurus propinquus is here assigned to and considered a junior synonym of Rhomaleosaurus zetlandicus. Currently only three valid species of the genus Rhomaleosaurus are known; a complete revision of the specimens formerly attributed to Rhomaleosaurus must now be carried out.

C. H. Holland: Pisocrinus from the type Ludlow Series (pp. 143-144)

SUMMARY: A unique specimen of Pisocrinus ?pilula is recorded and described from the Middle Elton Formation (Ludlow Series, Gorstian Stage) in the Ludlow district.

W. A. Fairburn: Landforms and the geological evolution of the Vale of York during the Late Devensian (pp. 145-154)

SUMMARY: Preliminary landform mapping over the York terminal moraine showed that persistent terraces on the sides of the moraine are strandlines that must have formed during regression of pro-glacial Lake Humber. Of widespread significance is a conspicuous shoreline between 30 and 35 m above OD that lasted for sufficient time to develop both erosional and depositional lacustrine terraces. This surface is contemporaneous with the 100 Foot Strandline mapped on the western side of the Vale of York, on the Permian escarpment. Between the Escrick and York moraines there are two additional major strandlines, with associated littoral and lacustrine deposits, that effectively subdivide the fluvioglacial sediments of the Vale of York into three offlapping planar landforms, with lateral erosional contacts independent of lithology. Above the 100 Foot Strandline, mounds and ridges of till form prominent landmarks, such as Severs Howe near York. The North Sea ice could not have plugged the Humber mouth until the Vale of York glacier had formed the York Moraine, and must have remained long enough for a prolonged stillstand of Lake Humber at c. 33 m above OD. Subsequent stillstands, recorded on the southern face of the York Moraine at c. 20 m and c. 14 m above OD (lowering to c. 15 m and c. 10 m above OD at Escrick), mark stages in the unplugging of the Humber mouth from either ice or till. The mapping also suggests that the Crockey Hill ‘esker’ consists of erosional remnants, preserved on interfluves, of a fluvial gravel sheet.

S. K. Donovan: John Phillips and the British Silurian Crinoidea: 170 years of monographic endeavour (pp. 155-164)

SUMMARY: John Samuel Miller’s A Natural History of the Crinoidea or Lily-Shaped Animals . . . (1821), the first monograph of the fossil crinoids, included only three species from what we would now call the British Silurian. The first monographic study devoted to the British Silurian crinoids was by John Phillips (in Murchison’s The Silurian System, 1839), who described 14 species (eleven new), all from the Wenlock Series of the area around Dudley. These were conservatively placed in five genera, Cyathocrinites Miller, Marsupiocrinites Phillips, Hypanthocrinites Phillips, Actinocrinites Miller and Dimerocrinites Phillips; the same species are now divided between eleven genera. Eight of these taxa are type species, but none is now classified as either Cyathocrinites or Actinocrinites. Hypanthocrinites is a junior synonym of Eucalyptocrinites Goldfuss. The illustrations in Phillips, drawn by J. de C. Sowerby, were much superior to Miller’s plates, but lacked his innovative ‘exploded’ diagrams.

 I. D. Somerville, P. Cózar, M. Aretz, H.-G. Herbig, W. I. Mitchell and P. Medina-Varea: Carbonate facies and biostromal distribution in a tectonically controlled platform in northwest Ireland during the late Viséan (Mississippian) (pp. 165-192)

SUMMARY: The North–West Carboniferous Basin (NWCB) contains a c. 3 km-thick succession of Mississippian (Courceyan to Arnsbergian) limestone, mudstone and sandstone, mostly of marine origin. The litho- and biostratigraphy of some sections in the basin are revised and new logged sections described in upper Viséan, limestone-dominated platform successions. In the O’Donnell’s Rock area, a precise correlation of the Glencar Limestone Formation with the lower part of the Bricklieve Limestone Formation, and the Dartry Limestone Formation with the upper part of the Bricklieve Limestone Formation is confirmed. Consequently, in late Viséan (Asbian) times the NWCB developed as an extensive (>12,000 km2) carbonate platform, in which sediments of the facies typical of outer, middle and inner parts of the platform were deposited. The Asbian rocks of this platform contain abundant solitary and fasciculate rugose corals, with laterally persistent biostromes dominated by different species of Siphonodendron. Evidence of regional uplift and subaerial exposure occurs at the top of the Dartry Limestone/Bricklieve Limestone formations, especially in the northern half of the platform. The base of the succeeding Meenymore Formation is defined by a change from marine limestone below an erosional disconformity surface, to sediments deposited on a sabkha and in supratidal–peritidal facies. Evolution of the platform was controlled, in part, by syn-sedimentary faults, which allowed different thicknesses of sediment to accumulate. Between the margins of the NWCB there existed a turbid carbonate platform with relatively shallow to moderately deep water characterized by impoverished microfaunal assemblages. The platform margin extended SE into deeper water facies of the Dublin Basin.

 J. K. Wright: The geology of the Corallian ridge (Upper Jurassic) between Gilling East and North Grimston, Howardian Hills, North Yorkshire (pp. 192-216)

SUMMARY: The northern edge of the Howardian Hills, running for 25 km from Gilling East to North Grimston, North Yorkshire, comprises a near-continuous ridge of Oxfordian limestones and calcareous sandstones, here termed the Corallian ridge. These strata rise gently from the Vale of Pickering up to a steep scarp face which overlooks underlying Oxford Clay to the south. The limestones and sandstones belong to the Corallian Group, which in the Howardian Hills includes the Lower Calcareous Grit, Coralline Oolite and Upper Calcareous Grit formations. The Lower Calcareous Grit Formation comprises a succession of finegrained, calcareous or spicular, siliceous sandstones, and forms a prominent feature. The Coralline Oolite Formation underlies gently rolling hills leading down to the Vale of Pickering, and is composed of a series of oolitic and fine-grained limestones with subordinate calcareous sandstones and sandy limestones. The Upper Calcareous Grit is represented here largely by calcareous strata, the North Grimston Cementstone, and is only exposed in faulted inliers to the south. The sequence was laid down in a tectonically active area, and movement of faults during deposition of the strata in the Mid Oxfordian led to marked changes in thickness and lithology across the area. Complications caused by these penecontemporaneous movements have meant that, though the outcrop has been investigated by numerous geologists over the last 150 years, the exact sequence of strata present and its correlation with the Corallian sequence on the north side of the Vale of Pickering have long presented problems. Much that was uncertain about the geology of the area has been resolved through detailed mapping of the area west of Malton.

 J. W. Tilsley and D. Korn: Chadian (Tournaisian–Viséan, Carboniferous) ammonoids from the Milldale Limestone Formation of the southern Peak District, England (pp.217-234)

SUMMARY: Ammonoids from the Chadian Waulsortian mud-mounds of the Peak District (Derbyshire and Staffordshire) have been examined utilizing new collections and additional museum material. The genera Fascipericyclus, Ammonellipsites, Helicocyclus, Dzhaprakoceras, Eonomismoceras, Polaricyclus and Merocanites are present. One new species, Eonomismoceras wettonense sp. nov., is described. The independent status of Fascipericyclus fasciculatus and F. furcatus is confirmed.

 Obituary: George Anthony Lobjoit Johnson 1925–2009 (pp. 235-236)                                                                  

 Society Proceedings, 2008 (pp. 237-242)

Index to Volume 57 (pp. 243-248)

Title Page and Contents for Volume 57, 2008-2009  (pp. i - iv)

Some British Geological Survey Memoirs for Yorkshire to download

In a major new development for the Society, the British Geological Survey (BGS) had made available to the Society's website full facsimile copies (in PDF format, including all illustrations) of some earlier Geological Survey Memoirs, listed below. These are now available for downloading for personal, academic, educational, non-commercial research and other non-commercial use, from the Yorkshire Geological Society website http://www.yorksgeolsoc.org.uk/ only. All users must agree to the BGS terms and conditions before downloading each Memoir.

Yorkshire Rocks and Landscape – the popular YGS Field Guide, Third Edition, is now available

Yorkshire, famed for its scenic beauty and its rich industrial heritage, contains some of the most interesting geology and scenery in England , from the moors to the coast, including the Yorkshire Dales and North York Moors national parks. The influence of the geology on the landscape and on the industrial development in the region is profound.  

A major Yorkshire Geological Society Publication!

Carboniferous Hydrocarbon Geology: the southern North Sea and surrounding onshore areas

edited by

John Collinson, David Evans, Doug Holliday & Neil Jones, 2005

Click here for full details and samples
of the full colour illustrations!

Price now reduced to £10 plus £5 p. & p. Cheques should be made payable to Yorkshire Geological Society. Please send your order form to: Dr J H Powell, British Geological Survey, Keyworth, Nottingham, NG12 5GG

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