Facies, stratigraphy, and evolution of a middle Ediacaran carbonate ramp: Khufai Formation, Sultanate of Oman

Abstract

The Khufai Formation is the oldest carbonate platform of the Cryogenian to lowermost Cambrian Huqf Supergroup. A stratigraphic characterization of this unit includes detailed facies descriptions, a sequence-stratigraphic interpretation, and evaluation of lateral heterogeneity and overall ramp evolution. The Khufai Formation comprises one and one-half depositional sequences with a maximum flooding interval near the base of the formation and a sequence boundary within the upper peritidal facies. Most of the deposition occurred during highstand progradation of a carbonate ramp. Facies tracts include outer-ramp and midramp mudstones and wackestones, ramp-crest grainstone shoal deposits, and extensive inner-ramp, microbially dominated peritidal deposits. Outcrops in the Oman Mountains are deepwater deposits, including turbiditic grainstone and wackestone interbedded with siliciclastic-rich siltstone and crinkly laminite. Facies patterns and parasequence composition are variable both laterally across the outcrop area and vertically through time because of a combination of ramp morphology, siliciclastic supply, and possible syndepositional faulting. The lithostratigraphic boundary between the Khufai Formation and the overlying Shuram Formation is gradational and represents significant flooding of the carbonate platform. The stratigraphic characterization presented here along with the identification of key facies and diagenetic features will help further future exploration and production of hydrocarbons from the Khufai Formation.

Uncovering the spatial heterogeneity of Ediacaran carbon cycling

“…C–S chemostratigraphy of successions capturing typical Shuram excursion in South China (a), Mexico (b), southwest USA (c), and Oman (d) where paired carbonate‐associated sulfate ( CAS ) and C‐isotope data were reported. Note: All chemostratigraphic data capturing the early onset of the SE (<120 m) in (d) were normalized to a thickness of 120 m based on the base and top surfaces of the Khufai Formation (Osburn, Grotzinger, & Bergmann, ), while the >120‐m data capturing the rest of the Shuram excursion were normalized to a thickness of 240 m in order to match the normalized thickness of <120 m for the Khufai Formation. Data sources: South China, this study and Li et al.…”

Depositional facies and platform architecture of microbialite-dominated carbonate reservoirs, Ediacaran–Cambrian Ara Group, Sultante of Om

“…The Huqf Supergroup is well exposed in central and northern Oman, including the Huqf area and the Oman Mountains (Gorin et al, 1982;Mattes and Morris, 1990;Wright et al, 1990) in the Mirbat area of southern Oman (Kellerhals and Matter, 2003;Mercolli et al, 2006) (Figure 1), and is intercepted in numerous wells in the SOSB (Al-Siyabi, 2005). The Huqf Supergroup is subdivided into three groups (Gorin et al, 1982;Mattes and Morris, 1990;Wright et al, 1990;Schröder et al, 2005;Osburn et al, 2014) (Figure 2). The lowermost unit is the Abu Mahara Group, which consists of glacial clastics.…”

Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China

“…If our basin-scale correlation for the Doushantuo Formation is correct, the strongly 13 C-depleted authigenic signatures revealed from the uppermost Doushantuo Formation at Zhongling could immediately precedes EN3, or could be time-equivalent to EN3a at the Jiulongwan section, suggesting a potential linkage between methane oxidation, sea level regression, and the onset of the Shuram Excursion (Bjerrum and Canfield, 2011). Indeed, sedimentological observations of the Shuram Excursion from other sections in South China , Death Valley (Summa, 1993;Corsetti and Kaufman, 2003;Kaufman et al, 2007;Bergmann et al, 2011), Oman (Fike et al, 2006;Le Guerroué et al, 2006b, 2006cLee et al, 2013;Osburn et al, 2014), South Australia (Husson et al, 2012(Husson et al, , 2015b, and NW Canada have also revealed a regression immediately before the onset of the Shuram Excursion, supporting our hypothesis.…”