Salt removal and sedimentation in Southern Oman

Abstract

On the Eastern Flank of the South Oman Salt Basin lies a Cambrian to Recent sequence much affected by the withdrawal and dissolution of underlying Infracambrian salt. Salt withdrawal began after burial by only a few hundreds of metres of Cambrian continental sands, and salt dissolution has taken place periodically up to the present, initially near-surface and later in the subsurface. Salt removal has (1) resulted in the collapse of masses of dolomite and shale formerly interbedded with the salt, (2) influenced the large-scale geometries of sedimentary bodies within the overlying succession, (3) affected the distribution of sedimentary facies when rates of salt removal balanced or exceeded sedimentation, (4) allowed the preservation of parts of the succession otherwise eroded at this basin margin, and (5) caused folding and fracturing of Cambrian to Recent sediments.More than 2 • 109 m 3 of oil (12 • 109 bbls) is estimated to be present in four types of hydrocarbon trap related to salt removal. In terms of importance these are: large turtleback anticlines resulting from the inversion of former peripheral synclines, truncation traps rimming eroded turtle-back anticlines, small anticlines draped over residual masses of dolomite and shale, and porous and fractured dolomites within such residual masses.

Effect of Permo-Carboniferous Climate on Illite-Smectite, Haushi Group, Sultanate of Oman

“…The source of the A1 Khlata material is more difficult to explain. The general S-N and SE-NW orientation of meltwater channels in south Oman (Heward, 1990;Silva et al, 1996) indicates that the main source for the A1 Khlata material was Proterozoic basement and Paleozoic siliciclastic sediments from south Oman and neighboring 9. al., 1999).…”

Ghaba salt basin province and Fahud salt basin province, Oman; geological overview and total petroleum systems

“…Pre-existing, highly variable topography caused major variations in sediment infill and syndepositional movement of the underlying salt (halokinesis) and differential subsidence across basement highs influenced thickness and lateral extent of these clastics (Aley and Nash, 1985: Heward, 1990: Loosvelt and others, 1996.…”

“…Several potential petroleum-source rocks have been identified in the stratigraphic section of Oman and range in age from Proterozoic to mid-Tertiary; however, organic-rich source rocks of Tertiary age are thermally immature (Grantham and others, 1988;1990). Grantham and others (1988;1990) and Al-Ruwehy and Frewin (1998) have identified five chemically distinct types of crude oils in Oman that are best identified by distinct biomarkers and carbon isotope values.…”

“…Grantham and others (1988;1990) and Al-Ruwehy and Frewin (1998) have identified five chemically distinct types of crude oils in Oman that are best identified by distinct biomarkers and carbon isotope values. Four of these oil types are linked to source rocks from the following: 1) a broad group of oils from the Infracambrian Huqf Supergroup, 2) the Lower Silurian Sahmah Formation of the Safiq Group (Droste, 1997), 3) the Middle Cretaceous Natih Formation, and 4) the Upper Jurassic Diyab (Grantham and others, 1988;1990) or Tuwaiq/Hanifa equivalents (Lake, 1986;Al-Ruwehy and Frewin, 1998) source. A fifth type, referred to as 'Q-type' or 'questionable source' oils, has characteristics and occurrences that suggest a separate source unit of the Huqf Supergroup others, 1988, 1990) presumably prevalent in the Ghaba Salt Basin (Guit and others, 1995;Al-Ruwehy and Frewin, 1998;Richard and others, 1998a, b).…”

Evidence for multiple ice centres during the late Palaeozoic ice age in Oman: outcrop sedimentology and provenance of the Late Carboniferous–Early Permian Al Khlata Formation

“…Morton 1959;Helal 1965;McClure 1980;Hambrey & Harland 1981;Braakman et al 1982;Levell et al 1988;McClure et al 1988;Heward 1990;Ferguson & Chambers 1991;McGillivray & Al-Husseini 1992;Al-Belushi et al 1996;Stephenson & Osterloff 2002;Aitken et al 2004;Osterloff et al 2004a;Melvin & Sprague 2006). These studies reveal a stratigraphic record that consists almost exclusively of sedimentary successions deposited within glaciated continental environments.…”