Hadhramaut Gr
Type Locality and Naming
"The Hadhramaut Group embraces the largely carbonate sequence between the Cretaceous – Cenozoic boundary and the regional mid-Cenozoic break. Upward succession of the Umm er Radhuma Fm, Rus Fm, Dammam Fm. Reference section: South Yemen and Dhofar tablelands. Dhulaima-2 is here proposed as the Omani reference well. Although Hughes Clarke (1988) proposed Biladi-1 as the reference well for all three individual formations, Dhulaima-2 has a much more complete and better-quality data set, e.g., wireline logs." Column: Oman Subsurface,
Synonym: "The Umm er Radhuma Fm, Rus Fm, Dammam Fm triad has been referred to as the Hasa Gr (Owen and Nasr, 1958) in northern Gulf areas. Use of the Hadhramaut Gr reflects the rather wider lithological variation in Oman."
Lithology and Thickness
Limestone. The sequence is punctuated by a median evaporitic phase, the Rus Fm, which separates a lower thick carbonate unit, the Umm er Radhuma Fm, from an upper unit, the Dammam Fm, which may be dominantly carbonate, or significantly marly or shaly. "Sequence stratigraphy: Mega- sequence AP10 (Sharland et al., 2001). Sharland et al. (2001) position their MFS Pg20 and MFS Pg10 surfaces within the Dammam Fm and Umr Er Radhuma Fm (Shammar Member), respectively. The presence of Early Paleocene (Danian) sediments is subject to debate."
Relationships and Distribution
Lower contact
The lower boundary is a hiatus or disconformity onto the Aruma Gr (Simsima Fm). The latest Maastrichtian through Danian are generally absent. Where the basal Shammar Mbr shales lie upon Fiqa Fm shales recognition of the boundary may require age determination by fossils, which is also the case where the Shammar is absent, e.g., to the east, and the unit overlies older carbonates.
Upper contact
Regional extent
"Potentially present throughout Oman. North, in the Al Hajar Mountains, the evaporitic Rus facies is not developed and other variations occur (Nolan et al., 1986). Over the Al Huqf axis outcrop areas and eastern Central Oman, the Lower Tertiary is absent by erosion.
GeoJSON
Fossils
"Al Zedjaly (1998) documents the Tertiary Micropaleontological zonation applied to the Group. However, some of the original work dates back to the 1960s, and the zonation is almost certainly in much need of revision. In particular the implied Late Eocene and Early Paleocene ages need to be further investigated."
Age
Depositional setting
Additional Information