An ocean‐facing Aptian–Albian carbonate margin, Oman

Abstract

A high‐energy Aptian–Albian platform margin in northern Oman fronted onto an open oceanic basin, making the area a valuable analogue for coeval guyot margins. Most similar aged carbonate margins described in the literature faced either intracratonic or minor oceanic basins. The studied margin is characterized by a stabilized outer rim, which, although it did not rise discernibly above the adjacent lagoonal deposits, flanked a steep upper slope (32–40°) basinwards with a relief of at least 30 m. Two main facies provided the rigidity of the outer margin: Lithocodium boundstones that constituted up to 50% of the rock volume; and marine fibrous cements that occluded up to 35% of primary pore space. In contrast, coral–rudist patches and other shelly sessile benthos were distributed irregularly, and the rudist bioherms of the outer margin were often disrupted, with shells being transported and redeposited. The inner margin is characterized by wedge‐shaped storm layers that radiate from the platform top lagoonwards, where they interdigitate with carbonate sands and small rudist bioherms. Polygenetic discontinuity surfaces that bear evidence of both marine hardground and subaerial exposure stages are prominent features of the margin. Throughout the latest Aptian to Middle Albian, the platform succession recorded some 30 relative sea‐level falls, of which seven reached amplitudes of many tens of metres. These seven high‐amplitude falls in sea level are recorded across the entire south‐eastern portion of the Arabian craton and are probably of eustatic origin.

Cenomanian rocks in the Sinai Peninsula, Northeast Egypt: Facies analysis and sequence stratigraphy

“…7F). This is similar to that described in the sequence boundaries in the Jurassic and Cretaceous shallow-marine carbonate platform of France, Spain and Oman by Hillgärtner (1998), Molina et al (1999) and Immenhauser et al (2001), respectively who ascribed the brecciation in the carbonate platforms to their karstification during an episode of sea-level fall and exposure. At Gabal Khashm El-Tarif, the occurrence of fenestral or bird eyes fabric in the lime-mudstone facies (Fig.…”

Response and recovery of the Comanche carbonate platform surrounding multiple Cretaceous oceanic anoxic events, northern Gulf of Mexico

“…12). Nonetheless, ages published for the Blake Nose profile and the Nahr Umr Formation (Immenhauser et al, 2001;Immenhauser and Scott, 2002) provide some time constraints and foram zonations are provided in Giorgioni et al (2012). Although the data from Oman have been extensively overprinted by subaerial exposure surfaces, the broader trends created by successive samples appear consistent with other data sets.…”

“…Powdered samples from the Shell Tomasek #1 core were sent to the Analytical Laboratory for Paleoclimate Studies of the University (Schlanger and Jenkyns, 1976;Scholle and Arthur, 1980 and cementation of primary porosity (Dickson and Coleman, 1980;Allan and Matthews, 1982;Immenhauser et al, 2001;Moore, 2001). In addition, d…”

“…Reference profiles for the Albian include those from the Apennine Mountains of the western Tethys (Giorgioni et al, 2012), Resolution Guyot (Jenkyns, 1995), northern Mexico (Scholle and Arthur, 1980;Bralower et al, 1999), the Nahr Umr Formation of Oman (Immenhauser et al, 2001), and Blake Nose in the western Atlantic (Wilson and Norris, 2001). Correlations are hampered by the lack of a time-calibrated d 13 C reference curve (Fig.…”

Fluid flow reconstruction in hanging and footwall carbonates: Compartmentalization by Cenozoic reverse faulting in the Northern Oman Mountains (UAE)

“…10). Isotopic studies on Aptian-Albian and Aptian to Cenomanian limestones in Jebel Akhdar in Oman report respectively a mean oxygen isotopic composition of À4.2% (s ¼ 1.2%) and a mean carbon isotopic composition of +1.9% (s ¼ 0.9%; Immenhauser et al, 2001) and ranges for d 18 O between À7.2 and À2.4% and for d 13 C between +0.5 and +3.6% (Hilgers et al, 2006). Budd (1989) performed stable isotope analyses on core samples of several wells in a Thamama reservoir in the Arabian Gulf.…”