Location of Repository

Evidence for Cenozoic tectonic deformation in SE Ireland and near offshore.

By M.J.M. Cunningham, W.E.A. Phillips and A.L. Densmore

Abstract

An integrated study of topography, bathymetry, high-resolution aeromagnetic data, and structural observations demonstrates significant Cenozoic fault activity in SE Ireland. Tectonically generated knickpoints and reddened fault breccias along topographic escarpments that are underlain by greywacke bedrock and trend oblique to the regional Caledonian strike provide evidence for fault displacement. Near-offshore faults with similar geometry produce present-day bathymetric scarps and localized tectonic topography in the inverted Kish Bank Basin. The integration of offshore high resolution aeromagnetic data and structural interpretation of the Kish Bank Basin provides evidence for dextral transtension on NNW trending faults and sinistral transpression on ENE trending faults bounding a lower Paleozoic to Carboniferous basement block. These faults correlate onshore with previously recognized Caledonian faults producing topographic offsets and surface uplift. To the north, offshore structures can be traced onshore and cut exposures of the Caledonian Leinster Granite. Structural analysis of these outcrops indicates post-Variscan deformation. A major fault on the NW margin of the batholith cuts a major erosion surface developed on Carboniferous carbonate rocks, and nonmarine Miocene deposits are preserved above this surface. Fault kinematics provide evidence of two paleostress systems: (1) NW-SE σ1, subvertical σ2 and NE-SW σ3 followed by (2) a clockwise swing of σ1 to NNW-SSE. Timing of deformation in both stress systems is probably post-Oligocene age. The mechanism driving this deformation is likely ridge-push. Much is already known about Cenozoic tectonics and exhumation from offshore basins. This study shows that onshore Ireland has also been affected by significant tectonic activity and exhumation during the Cenozoic

Publisher: American Geophysical Union
Year: 2004
DOI identifier: 10.1029/2003TC001597
OAI identifier: oai:dro.dur.ac.uk.OAI2:7232
Journal:

Suggested articles

Preview

Citations

  1. (1997). A pre-Pliocene or Pliocene land surface in County Galway, Ireland, in Palaeosurfaces: Recognition, Reconstruction and Palaeoenvironmental Interpretation,
  2. (1989). Alpine tectonics: An overview, in Alpine Tectonics,
  3. (1996). Cenozoic compressional structures on the NE Atlantic margin: Nature, origin and potential significance for hydrocarbon exploration,
  4. (2000). Cenozoic tectonics of western Ireland,
  5. (1966). Cyclic surfaces in the Roundwood Basin, county Wicklow,
  6. (2003). Evidence for post-early Eocene tectonic activity in southeastern Ireland,
  7. (2002). Exhumation of the North Atlantic margin: Introduction and background, in Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration, edited by
  8. (1997). Hillslope evolution by bedrock landslides,
  9. (2001). Hydrocarbon potential of the Kish Bank Basin: Integration within a regional model for the Greater Irish Sea Basin, in The Petroleum Exploration of Ireland’s Offshore Basins,
  10. (2001). Interpretation of vitrinite reflectance profiles in sedimentary basins, onshore and offshore Ireland, in The Petroleum Exploration of Ireland’s Offshore Basins,
  11. (1999). Interpretation of vitrinite reflectance profiles in the Central Irish Sea area: Implications for the timing of organic maturation,
  12. (1980). Major transverse and other linears in the Leinster Granite,
  13. (1990). Plate reorganisation: A cause of rapid late Neogene subsidence and sedimentation around the North Atlantic?,
  14. (2000). Post-Carboniferous pre-Quaternary karstification in Ireland,
  15. (1999). Principal tectonic events in the evolution of the northwest European Atlantic margin, in Petroleum Geology of Northwest Europe:
  16. (1987). The Goban Spur exploration in a deep water frontier basin, in Petroleum Geology of North West Europe,
  17. (1927). The topographical features of the granite-schist junction in the Leinster chain,
  18. (1989). Thermal maturation levels in the Devonian and Carboniferous rocks in Ireland,
  19. (2001). Understanding Irish landscape evolution: Pollen assemblages from Neogene and Pleistocene palaeosurfaces in western Ireland,
  20. (1987). Uplift determination from interval velocity studies, UK, southern North Sea,

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.