--> Abstract: A Tale of Two Glaciations, by Pieter Spaak and Malcolm Ross; #90105 (2010)

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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

A Tale of Two Glaciations

Pieter Spaak1; Malcolm Ross2

(1) Exploration New Ventures, SHELL E&P, Rijswijk, Netherlands.

(2) Research & Technology, SHELL E&P, Houston, TX.

Two major glacial events left their imprint on the Palaeozoic successions of Arabia. Glacial and post-glacial sediments of the Al Khlata and Unayzah ‘formations’ are the reservoirs of numerous Permo-Carboniferous fields in southern and central Arabia. Latest Ordovician glacial deposits and erosional remnants form the target of wells and prospects in south and north Arabia. Moreover, the Base Silurian post-glacial flood is the most significant (Qusaiba) source rock of the region.

The extent of the Late Ordovician and Permo-Carboniferous ‘ice-sheet’ is tremendous, covering in both cases very large parts of Gondwana. In that context, it is remarkable that during the Devonian, ice-cover over Gondwana is limited, notwithstanding a ‘very polar’ position of the super-continent in that period.

In this contribution, we will document the observations outlined above and will discuss the combination of plate configuration, polar position and the Hadley Circulation as a possible explanation for a relative ice-free Devonian compared to the preceding and subsequent periods.