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PALAEOZOIC SANDSTONE RESERVOIRS OF THE HAMADA BASIN, NW LIBYA: EFFECTS OF SYNSEDIMENTARY PROCESSES ON POROSITY
Author(s) -
Shah S. H. A.,
Mansouri A.,
Ghoul M. El
Publication year - 1993
Publication title -
journal of petroleum geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 42
eISSN - 1747-5457
pISSN - 0141-6421
DOI - 10.1111/j.1747-5457.1993.tb00343.x
Subject(s) - geology , paleozoic , clastic rock , geochemistry , precambrian , devonian , basement , structural basin , petrology , conglomerate , outcrop , geomorphology , metamorphic rock , civil engineering , engineering
The Hamada Basin of NW Libya is an intracratonic basin in which a thick sequence of clastic rocks was deposited during the Palaeozoic. These sediments were derived from a PreCambrian basement of felsic igneous and metamorphic rocks, and include both sands and clays; almost all the clays in formations of Palaeozoic age were produced from the alteration of feldspar. Structures were developed as these sediments were draped over the surface of the basement. Reservoirs in the Lower Palaeozoic (Lower Devonian, Lower Silurian and Cambro‐Ordovician Sandstones) appear to have developed as a result of synsedimentary processes, such as winnowing and washing‐out of clayey material from the sand by percolating waters, and sliding and slumping on the steep depositional surface during or soon after deposition. Oil traps are independent of structural elevation, but appear to have developed on those surfaces which were sufficiently steep to have initiated the above synsedimentary processes. This theory has been successfully tested in many places in the basin, and may provide a lead for exploration in other basins in Libya that have similar geological settings.