『Abstract
　Exhumation, the removal of overburden resulting from the vertical displacement of rocks from maximum burial depth, occurs at both regional and local scales in offshore sedimentary basins and has important implications for the prospectivity of petroliferous basins. In these basins, issues to be addressed by the petroleum geologist include, the timing of thermal ‘switch-off’ of source rock units, the compactional and diagenetic constraints imposed by the maximum burial depth of reservoirs (prior to uplift), the physical and mechanical characteristics of cap-rocks during and post-exhumation events, estimate their magnitude and deduce their timing. A variety of individual techniques is available to assess the exhumation of sedimentary successions, but generic categorisation indicates that ‘point’ measurements of rock displacement, in the offshore arena, are made with respect to four frames of reference - tectonic, thermal, compactional or stratigraphic. These techniques are critically reviewed in the context of some of the exhumed offshore sedimentary basins peripheral to the Irish landmass. This review confirms that large uncertainty is associated with estimates from individual techniques but that the integration of seismic interpretation and regional stratigraphic data provides valuable constraints on estimates from the more indirect tectonic, thermal and compactional methods.

Keywords: exhumation; techniques; magnitude; timing; offshore basins』

1. Introduction and definition of exhumation
2. Why measuring exhumation is important
3. Irish landmass and offshore basins - an exhumation laboratory
4. Techniques for assessment of exhumation
5. Tectonic based techniques
6. Thermal history-based techniques
7. Compaction-based techniques
8. Stratigraphic correlation-based techniques
9. Comparison of exhumation estimates derived from different methods, illustrated using wells drilled in basins offshore Ireland
　9.1. Celtic Sea Basins
　9.2. Kish Bank, Central Irish Sea and St. George's Channel basins
　9.3. Porcupine Basin
　9.4. Slyne/Erris Basins
　9.5. East Irish Sea Basin
10. Discussion and conclusions
Acknowledgements
References

Table 1 Exhumation/uplift lexicon - summary definitions. The preferred terms used in this paper, net exhumation and gross exhumation are shown in italics at bottom of Table

Term	Summary definition	Frame of reference	Spatial-wavelength
Uplift	Non specific term referring to displacements “opposite to the gravity vector” (England and Molnar, 1990)	Object displaced and/or reference frame not specified	Not specified
Surface uplift	Displacement of Earth's surface averaged over area＞103-104km2 (England and Molnar, 1990)	Geoid or mean sea level	Long
Crustal uplift	Also ‘uplift of rocks’ - vertical displacement of rock column (England and Molnar, 1990: Dore （eの頭に´）et al., 2002a)	Geoid or mean sea level	Short
Net uplifta	Present elevation of a marker bed above its maximum burial depth (Riis and Jensen, 1992; Dore（eの頭に´） and Jensen, 1996)	Ground level or seabed	Short
Epeirogeny	Broad regional uplift of continental interiors driven by thermal, isostatic or intra-plate stress fields (Turner and Williams, 2004)	Geoid	Long
Inversion	Compressional reactivation of formerly extensional fault systems leading ultimately to extrusion of synrift fill (Cooper and Williams, 1989)	Pre-extensional regional elevation	Short and/or long
Erosion	Local subaerial or submarine removal of material by both mechanical and chemical processes (Ring et al., 1999; Riis, 1996)	Fixed subsurface coordinates	Short
Denudation	Loss of mass from both surface and subsurface parts of a drainage basin or regional landscape by all types of weathering, physical and chemical (Leeder, 1999)	Fixed internal reference axes within bedrock	Long
Exhumation	Descriptive term describing removal of overburden material such that previously buried rocks are exposed (Dore （eの頭に´）et al., 2002a)	Ground level	Short and/or long
Net exhumation	Difference between present-day burial depth of a reference unit and its maximum burial depth prior to exhumation (this paper)	Tectonic, thermal, compactional, stratigraphic (relative to seabed, ground-level, or stratigraphic marker)	Short
Gross exhumationb	Magnitude of erosion which must have occurred at a particular unconformity prior to post-exhumation re-burial (this paper)	Thermal, compactional, stratigraphic (relative to seabed, ground-level, or stratigraphic marker)	Short
a Other terms used in the literature which are synonymous with Net Uplift are: Apparent uplift (Scherbaum, 1982; Bulat and Stoker, 1987); Apparent exhumation (Hillis, 1995a,b); Negative burial anomaly (Japsen, 1998; Japsen et al., 2002); Net exhumation (this paper). b Term Gross exhumation (this paper) is synonymous with: Total exhumation or exhumation at time of denudation (Hills, 1995a,b); Lost cover (Cope, 1997); Removed section (Bray et al., 1992; Green et al., 2002)

• Bray,R.J., Green,P.F. and Duddy,I.R.(1992): Thermal history reconstruction using apatite fission track analysis and vitrinite reflectance: a case study from the UK East Midlands and Southern North Sea. In: Hardman,R.F.O.(Ed.), Exploration Britain: Geological Insights for the Next Decade. Geological Society Special Publication, 67, 3-25.
• Bulat,J. and Stoker,S.J.(1987): Uplift determination from interval velocity studies, UK Southern North Sea. In: Brooks,J. and Glennie,K.(RDs.), Petroleum Geology of North West Europe. Graham and Trotman, London, 293-305.
• Cooper,M.A. and Williams,G.D.(Eds.)(1989): Inversion Tectonics. Geological Society, London, Special Publications, 44.
• Cope,J.C.W.(1997): The Mesozoic and Tertiary history of the Irish Sea. In: Meadows,N.S., Trueblood,S.P., Hardman,M. and Cowan,G.(Eds.), Petroleum Geology of the Irish Sea and Adjacent Areas. Geological Society, London, Special Publications, 124, 47-59.
• Dore（eの頭に´）,A.G., Cartwright,J.A., Stoker,M.S., Turner,J.P. and White,N.J.(2002a): Exhumation of the North Atlantic margin: introduction and background. In Dore（eの頭に´）,A.G., Cartwright,J.A., Stoker,M.S., Turner,J.P. and White,N.(Eds.), Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration. Geological Society, London, Special Publications, 196, 1-12.
• Dore（eの頭に´）,A.G. and Jensen,L.N.(1996): The impact of late Cenozoic uplift and erosion on hydrocarbon exploration: offshore Norway and some other uplifted basins. Global and Planetary Change, 12, 415-436.
• England,P. and Molnar,P.(1990): Surface uplift, uplift of rocks, and exhumation of rocks. Geology, 18, 1173-1177.
• Green,P.F., Duddy,I.R. and Hegarty,K.A.(2002): Quantifying exhumation from apatite fission-track analysis and vitrinite reflevtance data: precision, accuracy and latest results from the Atlantic margin of NW Europe. In: Dore（eの頭に´）,A.G., Cartwright,J.A., Stoker,M.S., Turner,J.P. and White,N.(Eds.), Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration. Geological Society, London, Special Publications, 196, 331-354.
• Hillis,R.R.(1995a): Quantification of Tertiary exhumation in the United Kingdom Southern North Sea using sonic velocity data. American Association of Petroleum Geologists Bulletin, 78/1, 130-152.
• Hillis,R.R.(1995b): Regional Tertiary Exhumation in and around the United Kingdom. In: Buchanan,J.G. and Buchanan,P.G.(Eds.), Basin Inversion. Geological Society, London, Special Publications, 88, 167-190.
• Japsen,P.(1998): Regional velocity-depth anomalies, North Sea Chalk: a record of overpressure and Neogene uplift and erosion. AAPG Bulletin, 82, 2031-2074.
• Japsen,P., Bidstrup,T. and Lidmar-Bergstrom（oの頭に¨）,K.(2002): Neogene uplift and erosion of southern Scandinavia induced by the rise of the South Sweedish Dome. In: Dore（eの頭に´）,A.G., Cartwright,J.A., Stoker,M.S., Turner,J.P. and White,N.(Eds.), Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration. Geological Society, London, Special Publications, 196, 183-207.
• Leeder,M.R.(1999): Sedimentology and Sedimentary Basins. Blackwell Science, Oxford.
• Riis,F.(1996): Quantification of Cenozoic vertical movements of Scandinavia by correlation of morphological surfaces with offshore data. Global and Planetary Change, 12, 331-357.
• Riis,F. and Jensen,L.N.(1992): Introduction: Measuring uplift and erosion - proposal for a terminology. Norsk Geologisk Tids-skrift, 72, 223-228.
• Ring,U., Brandon,M.T., Willett,S.D. and Lister,G.S.(1999): Exhumation processes. In: Ring,U., Brandon,M.T., Lister,G.S. and Willett,S.D.(Eds.), Exhumation Processes: Normal Faulting, Ductile Flow and Erosion. Geological Society Special Publication, 154, 1-27.
• Scherbaum,F.(1982): Seismic velocities in sedimentary rocks; indicators of subsidence and uplift. Geologische Rundschau, 71, 519-536.
• Turner,J.P. and Williams,G.A.(2004): Sedimentary basin inversion and intra-plate shortening. Earth Science Reviews, 65, 277-304.