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Triassic fluvio-aelian sediments are the main reservoir in the Wytch Farm oilfield (South England ) and are also significant reservoir targets with the Viking Graben and along the north Atlantic margins, such as in the Corrib gas field (1997), offshore western Ireland. Although the Triassic sequences of the North Sea have been studied for a number of years, the limited well coverage means that there are still questions related to depositional setting and controls on reservoir architecture. The North Atlantic basins are less well constrained, although offer huge exploration potential. Due to onshore exposures, the Central Atlantic basins are more studied and better constrained than their counterpart of the North Atlantic and threfore present good analogues for the offshore basins. However their stratigraphy is still debated and their sedimentological analysis very limited.
The initial research project, funded by Shell E&P, aims to develop a better understanding of the continental depostional systems within the rift basins in the North Atlantic domain. The new phase of the project, funded by Shell EPX, aims to characterize the architecture of the fill of the Central Atlantic Triassic basins, and their spatial and temporal evolution in order to evaluate potential petroleum plays and assess the Triassic palaeogeography and geodynamics of the Central Atlantic domain.. The sediments were deposited in a collage of linked rifted basins which formed the pre-cursor to the Atlantic Ocean. The rift basins extend from eastern North America and West Africa, through the Iberian realm and west of Ireland to mid-Norway and eastern Greenland. The basins contain in-excess of 6 km of sediment, deposited during extension. The precise timing of rifting is poorly constrained due the the nature of the fill, which is dominated by alluvial facies, which vary from the deposits of very large perenial rivers to more ephemeral systems associated with aeolian, lacustrine and evaporitic conditions. The evolution of these systems was a response to multiple episodes of extension, climatic fluctuation and intermittent marine influence.
The research project involved undertaking fieldwork in the Triassic Fundy Basin of Nova Scotia, Canada, and then take a regional look at the rift system by compiling published stratigraphical, sedimentological, and structural data from basins located in the Central and North Atlantic realm. The research will allow the analysis of size and scale of the fluvial systems, the depositional / architectural style and allow and assessment of the associated drainage basins. The assessment of the stratigraphy will highlight the uncertainties in the timing of rift development and the structural data will classify basin architecture and allow the evaluation of the spatial and temporal evolution of the Atlantic Triassic early rift system, and possibly assess the controls on the rift development.
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| University of Aberdeen | |
Publications:
Leleu S. & Hartley A.J., 2010, Controls on the stratigraphic development of the Triassic Fundy basin, Nova Scotia: Implications for the tectono-stratigraphic evolution of Triassic Atlantic rift basins. Journal of Geological Society, London, 167, 1-18.
Leleu S., van Lanen X.M.T. & Hartley A.J., in press, Controls on the architecture of a Triassic sandy fluvial system, Wolfville Formation, Fundy Basin, Nova Scotia: Implications for the interpretation and correlation of ancient fluvial successions. Journal of Sedimentary Research
Leleu S., Hartley A.J. & Williams B.P.J., 2009. Large scale alluvial architecture and correlation within a Triassic pebbly braided river system, lower Wolfville Formation (Fundy Basin, Nova Scotia, Canada). Journal of Sedimentary Research, 79, 292-313.
Tyrrell S., Leleu S., Souders A. K., Haughton P.D.W. & Daly J.S.,.K-feldspar sand-grain provenance in the Triassic, west of Shetland: a first-cycle sedimentary fingerprint? Geological Journal, 44, 692-710.
Redfern, J., Shannon, P.M., Tyrrell, S., Leleu, S., Fabuel Perez, I., Baudon, C., Haughton, P.D.W. , Daly, J.S., Van Lanen, X., Štolfová, K., Hodgetts, D., Williams, B. P.J., Speksnijder, A., in press, An integrated study of Permo -Triassic basins along the North Atlantic passive margin: implication for future exploration, Barbican, Special Publications of the Petroleum Geology Conference.
Contributions to Conferences:
Leleu S., McKie T., Williams, B.P.J., 2006. The North Atlantic Triassic rift system: basins evolution and large scale drainage pattern. BSRG, Aberdeen.
Leleu S., Williams, B.P.J, Hartley A.J., 2006. Correlation, architecture and evolution within a fluvial basin-infill system: the early rift evolution of the Fundy Basin (Late Triassic, Nova Scotia). BSRG, Aberdeen.
Leleu S., Hartley A.J., Williams, B.P.J, 2007. Early infill of the Triassic rift in the Fundy Basin (Nova Scotia): assessment of the stratigraphy by correlative surfaces in fluvial barren sequences. AAPG, Long Beach, 1-4 April.
Leleu S., Hartley A. J., Jolley D. W., Williams B. P.J., 2008. The early infill of the Triassic Fundy Basin: architecture of the Wolfville Formation and fluvial evolution. Atlantic Conjuguate Margins, Halifax, 13-15 August.
Leleu S., 2008. Continental Rift basin fills: evolution from opened to closed stage (Wolfville/ Blomidon Fm, nova Scotia). Atlantic Conjuguate Margins, Halifax, 13-15 August.
Leleu S., Hartley A.J. 2009. North Atlantic Triassic rift basin fills: controls on the evolution from fluvial to playa stage. Abstract, 9th International Conference of Fluvial Sedimentology, Tucuman, Argentina.
Leleu S., van Lanen X., 2009. Braided rivers: a limit to depositional models. From river to Rock Record, Aberdeen, 12-14 January 2009.
Leleu S.,
Hartley A.J., Williams, B.P.J, 2009. Large-scale alluvial architecture and correlation within a Triassic pebbly braided river system (Fundy Basin, Canada). From river to Rock Record, Aberdeen, 12-14 January 2009
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| Unconformity between Carboniferous (vertical) and Triassic (slightly tilted) Lower Wolfville Fm in Pembroke, Nova Scotia, Canada. |
Triassic (Lr Wolfville Fm) fluvial channel filled by conglomates, incised (6m) in pebbly sandstones, Pembroke, Nova Scotia, Canada. |
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| Late Triassic aeolian dune, Five Island, Nova Scotia, Canada. |
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| Blomidon Fm, Late Triassic. Blomidon Park, Nova Scotia, Canada. |
Boundary between Late Triassic Blomidon Fm and Jurassic, below the basalt cap. Five Island, Nova Scotia, Canada. |
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| Late Triassic/Lower Jurassic Red Beds. Praia de Telheiro, Algarve, Portugal. |
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| Lidar set up on the field. Ready to scan... |
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