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Journal Articles The Geological Society, London, Special Publications Year : 2012

Late Ordovician tunnel valleys in southern Jordan

G. Douillet
  • Function : Author
J.-F. Ghienne
  • Function : Author
Yves Géraud
A. Abueladas
  • Function : Author
M. Diraison
  • Function : Author
A. Al-Zoubi
  • Function : Author

Abstract

Abstract The Upper Ordovician glacial record of southern Jordan (Ammar Fm.) essentially consists of palaeovalley infills and of a subordinate time-transgressive fluvial to shallow-marine succession overstepping both the palaeovalleys and interfluvial areas. Valley size (depth, 60–160 m; width, 1–3 km), steep (20–50°) margins, internal organization and depositional facies point to an origin as tunnel valleys. The tunnel valleys are infilled by either fluvioglacial sandstones or fluviodeltaic coarsening-upward successions including fine-grained clayey sediments. Re-occupation of previous valleys is evident in places. At least three generations of tunnel valleys are inferred from cross-cutting relationships, although they most probably only reflect temporary standstills and minor re-advances related to the overall recession following the main glacial advance recorded in Saudi Arabia. Petrophysical measurements indicate that higher permeabilities are located in the glacially related strata (1.5–3 darcy in fluvioglacial infills), with a somewhat reduced porosity (22–28%) relative to the preglacial sandstones owing to a higher clay content, probably of diagenetic origin. Sandstone amalgamation, however, gives the fluvioglacial sandstones a high reservoir quality.
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Dates and versions

hal-03698799 , version 1 (19-06-2022)

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G. Douillet, J.-F. Ghienne, Yves Géraud, A. Abueladas, M. Diraison, et al.. Late Ordovician tunnel valleys in southern Jordan. The Geological Society, London, Special Publications, 2012, 368 (1), pp.275-292. ⟨10.1144/SP368.4⟩. ⟨hal-03698799⟩
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