Gull Island Formation


Google remote image of coastal Co Clare where cliffs expose Gull Island Formation. Gull island approximately 500ft long and North is to right. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Gull Island Formation with solated turbidite-filled channels and large deformation structures signifying its slope origin. Cliff of Gull Island Formation with solated turbidite-filled channels at base of cliff and large deformation structures signifying its slope origin above. Cliff of Gull Island Formation with solated turbidite-filled channels at base of cliff and large deformation structures signifying its slope origin above. Gull Island Formation with large deformational structures interpreted to have been transported downslope from a deltaic source above. Gull Island Formation with large deformational structures interpreted to have been transported downslope from a deltaic source above. Gull Island Formation with large deformational structures interpreted to have been transported downslope from a deltaic source above. Base of section are amalgamated channel sands overlain by mix of mud, shale, silts and sand. Some are chanelled and some slumper and show softe sediment deformation. Gull Island Formation with large deformational structures interpreted to have been transported downslope from a deltaic source above. Mix of channel fill and slumped materials. Gull Island Formation with large deformational structures that are interpreted to have been transported downslope from a deltaic source above. Gull Island Formation with large deformational structures interpreted to have been transported downslope from a deltaic source above. Gull Island Formation with mix of channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note moncline to right. Monocline of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Monocline of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Monocline of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Monocline of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Monocline of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. To right edge note margin of large slump filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. To right edge note margin of large slump filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. To right edge note margin of large slump filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note largeslump filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note largeslump filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. To right edge note margin of large slump filled channel cut into rhythmic slope deposits of silt and mud. Cliff of Gull Island Formation composed of mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note margin of large slump filled channel cut into rhythmic slope deposits of silt and mud on island. Island cliff of Gull Island Formation exhibiting mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note margin of large slump filled channel cut into rhythmic slope deposits of silt and mud. Cliff at Tullig Point with mix of Tullig and Gull Island Formations. Note delta front silts and muds above, while below are Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large slump filled gauges cut into rhythmic slope deposits of silt and mud. Cliff at Tullig Point with mix of Tullig and Gull Island Formations. Note delta front silts and muds above, while below are Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large slump filled gauges cut into rhythmic slope deposits of silt and mud. Cliff at Tullig Point with mix of Tullig and Gull Island Formations. Note delta front silts and muds above, while below are Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large slump filled gauges cut into rhythmic slope deposits of silt and mud. Cliff at Tullig Point with mix of Tullig and Gull Island Formations. Note delta front silts and muds above, while below are Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large slump filled gauges cut into rhythmic slope deposits of silt and mud. Cliff at Tullig Point with mix of Tullig and Gull Island Formations. Note delta front silts and muds above, while below are Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large slump filled gauges cut into rhythmic slope deposits of silt and mud. Cliff at Tullig Point with mix of Tullig and Gull Island Formations. Note delta front silts and muds above, while below are Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Note large slump filled gauges cut into rhythmic slope deposits of silt and mud. Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Section contains condensed sections with Goniatites. Gull Island Formation mixed channel sands and lobes and large deformational structures interpreted to have been transported downslope from a deltaic source above. Beds of silty muds of Gull Island Formation whose bedding plane parting have a variety of features on their surfaces including ripples and goniatite fossils. Beds of channelled sands and silty muds of Gull Island Formation whose bedding plane partings have a variety of features on their surfaces including ripples and goniatite fossils. Beds of silty muds of Gull Island Formation whose bedding plane parting have a variety of features on their surfaces including ripples and goniatite fossils. Disrupted beds of channelled sands and silty muds of Gull Island Formation whose bedding plane partings have a variety of features on their surfaces including ripples and goniatite fossils. Beds of channelled sands and silty muds of Gull Island Formation whose bedding plane partings have a variety of features on their surfaces including ripples and goniatite fossils. Detail of disrupted beds of silty muds of Gull Island Formation whose bedding plane partings have a variety of features on their surfaces including ripples and goniatite fossils. Bedding plane of Gull Island Formation condensed section with Goniatites. Bedding plane of Gull Island Formation showing portion of condensed section with Goniatites. Bedding plane surfaces of Gull Island Formation showing a variety of features on surface including ripples and goniatite fossils. Bedding plane surfaces of Gull Island Formation exposing goniatite fossils. Bedding plane of Gull Island Formation showing portion of condensed section with Goniatites. Bedding plane of Gull Island Formation showing portion of condensed section with Goniatites. Bedding plane surfaces of Gull Island Formation exposing goniatite fossils. Bedding plane surfaces of Gull Island Formation exposing goniatite fossils. Bedding plane of Gull Island Formation showing portion load mottling of surface. Bedding plane of Gull Island Formation showing portion load mottling of surface. Bedding plane of Gull Island Formation showing portion load mottling of surface. Bedding plane of Gull Island Formation showing portion load mottling of surface. Bedding plane surfaces of Gull Island Formation showing a variety of features on surface including ripples and goniatite fossils. Bedding plane surfaces of Gull Island Formation showing a variety of features on surface including ripples and goniatite fossils. Bedding plane of Gull Island Formation showing rippled surface. Bedding plane of Gull Island Formation showing rippled surface. Bedding plane of Gull Island Formation showing rippled surface. Bedding plane surfaces of Gull Island Formation exposing goniatite fossils. Beds of channelled sands and silty muds of Gull Island Formation whose bedding plane partings have a variety of features on their surfaces including ripples and goniatite fossils.

Deepwater Gull Island - Gull Island Formation
 
Gull Island Formation Deepwater Margin Slumps and Condensed Sequences downslope from Basin margin.

Measured Section through the lower part of the Gull Formation at Gull Island. This section is exposed in one of the images in Gallery.
This gallery represents images of outcrops along Atlantic shore at Gull Island, just north of Shannon Estuary and Fisherman's Point in Co Clare. Here extensive slumps are punctuated by condensed sections with abundant Goniatites. Sediments probably accumulated close to base of basin margin slope where slumping occurred and was modified by  local channeling. Above slumped sediments are the deltaic sediments of the Tullig Formation. 
Summary Statement
Ole Martinsen in the SEPM guidebook (Martinsen et al.,2008) describes the Gull Island Formation as:

(1) Part of the Clare Basin sediment fill which is more than 1200 m thick and part of a succession of deepwater basin sedimentary fill. The mud-rich formation he divided into two parts:
(i) A lower onlapping turbidite system with axially fed shallow channels, channel-margin sheets and levee deposits and strongly influenced by slumping; and
(ii) An upper progradational system connected to overtying deltaic deposits with isolated turbidite-filled channels and fewer, but larger deformation structures signifying its slope origin.

(2) The lower part of the Gull Island Formation shows reservoir-type sandstones in a mud-rich turbidite system he interpreted as healed slope accommodation developed above ponded accommodation.

(3) The potential reservoir intervals are bounded by thick, slumped silty mudstone intervals. The lateral extent of these potential barriers exceeds the scale of outcrops (>300 m). Thin, hemipelagic shales are rare, but are potentially basin wide (>15 km) in extent and represent condensed horizons of probable eustatic origin.

(4) The upper part of the Gull Island Formation and the overlying deltaic deposits were controlled by regional accommodation probably related to sea level or regional tectonics. Potential reservoir sandstones within this prograding, mud-rich delta-fed slope were limited to isolated channel sandstones. This slope probably developed to grade as a response to decayed or ceased differential subsidence in the basin, increased sediment supply and regional sea level.

Photos by Christopher Kendall, and Peter Haughton.

Useful References
Brennand, R. P., 1965, The Upper Carboniferous (Namurian) stratigraphy north-east of Castle island, County Kerry, Ireland: Proceedings of the Royal Irish Academy, v. 64, sect. B, p. 41-63.

Collinson, J.D., Martinsen, O. Bakken, B. and Kloster, A. (1991), Early fill of the western Irish Namurian Basin: a complex relationship between turbidites and deltas. basin Research, 3, 223-242.

Gill, W. D., and Kuenen, P. H. 1958, Syndepositional sliding and slumping in the West Clare Namurian Basin, Ireland. Geol. Surv. Irel., Spec. Pub. 4, 1-121.

Lien, T., R. G. Walker, and O. J. Martinsen, 2003, Turbidites in the Upper Carboniferous Ross Formation, western Ireland: reconstruction of a channel and spillover system: Sedimentology, v. 50, p. 113-148.

Martinsen, O.J. (1989), Styles of soft sediment deformation on a Namurian (Carboniferous) delta slope, western Ireland Namurian Basin, Ireland. In Whatley, M.K.G. & Pickering, K.T. (eds) Deltas: sites and traps for fossil fuels, Geological Society Special Publication, 41, 167-177.

Martinsen, O.J. & Bakken, B. (1990), Extensional and compressional zones in slumps and slides in the Namurian of County Clare, Ireland. Journal of the Geological Society, 147, 153-164.

Martinsen, O. J., T. Lien, and R. G. Walker, 2000, Upper Carboniferous deep water sediments, western Ireland: analogues for passive margin turbidite plays, in P. Weimer, R. M. Slatt, J. Coleman, N. C. Rossen, H. Nelson, A. H. Bouma, M. J. Styzen, and D. T. Lawrence, eds., Deep-water reservoirs of the world, Gulf Coast Section-SEPM Special Publication, p. 533-555.

Martinsen, O. J., and J. D. Collinson, 2002, The Western Irish Namurian Basin reassessed—a discussion: basin Research, v. 14, p. 523-542.

Martinsen, O. J., T. Lien, R. G. Walker, and J. D. Collinson, 2003, Facies and sequential organization of a mudstone-dominated slope and basin floor succession: the Gull Island Formation, Shannon Basin, western Ireland: Marine and Petroleum Geology, v. 20, p. 789-807

Martinsen O., Sullivan M., Pulham A., Haughton P., Harper H., and Elliot T., 2008, Outcrops Revitalized; Tool, Techniques and Applications Kilkee, County Clare, Ireland June 22-27, 2008 Field Guide SEPM Research Conference pp 53

Pulham, A.J. (1987), Depositional and syn-sedimentary deformation processes in Namurian deltaic sequences of west County Clare, Ireland. Unpublished PhD thesis, University of Wales, Swansea.

Pulham, A.J. (1989), Controls on internal structure and architecture of sandstone bodies within Upper carboniferous fluvial-dominated deltas, County Clare, western Ireland. In Whatley, M.K.G. & Pickering, K.T. (eds) Deltas: sites and traps for fossil fuels, Geological Society Special Publication, 41, 179-203.

Ramsbottom, W. H. C., M. Calver, R. M. C. Eagar, F. Hodson, D. W. Holliday, C. J. Stubblefield, and R. B. Wilson, 1978, A correlation of Silesian Rocks in the British Isles: Special Report of the Geological Society of London, no. 10, 81 p.

Rider, M.H. (1969), Sedimentological studies in the West Clare Namurian Basin, Ireland and the Mississippi Delta. Unpublished PhD thesis, Imperial College London.

Rider, M.H. (1974), The Namurian of West County Clare. Proceedings of the Royal Irish Academy, 74B, 125-142.

Rider, M.H. (1978), Growth faults in the Carboniferous of western Ireland. Bulletin of the American Association of Petroleum Geologists, 62, 2191-2213.
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