Umm Er Radhuma Fm
Type Locality and Naming
Near Umm Radmah wells (lat 28°41’ N, long. 44°41’ E) in Saudi Arabia. M. Steineke, R.A. Bramkamp and N.J. Sander, 1958
Synonym: “Radhuma Formation”, Owen and Nasr, 1958. “Umm er Radhuma Formation”, van Bellen, 1959. “Formation de l’Umm er Radhuma”, Sander, 1962. “Umm er Radhuma”, Elder and Grieves, 1965. “Umm er Radhuma”, Dominguez, 1965. “Umm er Radhuma Formation”, Hajash, 1967. “Umm er Radhuma Formation”, Tschopp, 1967. “Umm er Radhuma Formation”, Fox and Brown, 1968.
Reference Section:
Q.P.C. Well Dukhan No. 22, lat 25°22’38” N, long. 50°48’34” E, elevation 41 m (146 ft), completed 12.6.1951, between drilled depths 61 and 389 m (201 and 1278 ft).
Lithology and Thickness
Top. 1. Limestone, light brown or light grey, mostly very dolomitic, very porous and with many small aggregates of quartz and chalcedony. 50 m (164 ft). 2. Dolomite, brown, grey brown and dark grey, saccharoidal, very porous, partly calcareous. 79 m (260 ft). 3. Limestone, light grey to grey-brown, variable dolomitic, with streaks of bluish-grey argillaceous limestone towards the bottom. 131 m (430 ft). 4. Argillaceous limestone, bluish-grey, with beds of blue marl. 53 m (175 ft). 5. Marl, blue-grey, mostly rather pyritic. 12 m (40 ft). Base. Its thickness is 328 m (1077 ft).
Relationships and Distribution
Lower contact
Simsima Fm, contact apparently conformable, but regionally disconformable. At the contact of grey marls or shales of the basal Umm er Radhuma, above, with grey argillaceous limestones and marls of the Simsima, below. There is a very sudden change from Maastrichtian to Paleocene microfaunas at the contact. Without this faunal change, accurate selection of the formation boundary could sometimes be very difficult. The chronological list of current rock units indicates the next older unit as Aruma Gr
Upper contact
Rus Fm; contact conformable. At contact of grey-brown, dolomitic limestone of the Umm er Radhuma, below, with white chalk of the basal Rus, above.
Regional extent
Found in all deep wells drilled in Qatar. Known to outcrop over large areas of Saudi Arabia, Oman and South Arabia; also, from wells in south Iraq, Kuwait, Bahrain and the Trucial States.
GeoJSON
Fossils
In 1. Lockhartia tipperi (Davies), L. hunti Ovey, L. hunti var. pustulosa Smout, Sakesaria cotteri Davies, Rotalia trochidiformis Lamarck, Nummulites globulus Leymerie. In 3. R. trochidiformis, Miscellanea meandrina (Carter), Sakesaria dukhani Smout, S. dukhani var. cordata Smout, Miscellanea miscella (d’Archiac and Haime), M. miscella var. dukhani Smout, Operculina sp., Daviesina langhami Smout, D. khatiyahi Smout, Kathina major Smout, K. selveri Smout, K. delseota Smout, Lockhartia diversa Smout, L. haimei (Davies), L. conditi (Nuttall), L. conica Smout, L. altispira Smout, Dictyokathina simplex Smout, Dictyoconus indicus Davies, Delheidia haydeni Douville. In 4. L. haimei, L. diversa, L. altispira, L. conditi, D. khatiyahi, Asterigerina dukhani Smout, Rotalia hensoni Smout, R. dukhani Smout, Lockhartia prehaimei Smout. In 5. L. prehaimei, L. conditi.
Age
Depositional setting
Additional Information
This formation exhibits remarkable uniformity of lithology and fauna over vast areas of Arabia. A similar rock unit can be found in many other areas of Tethyan sedimentation.
The basal shale-marl member of the Umm er Radhuma is of widespread occurrence, having been recorded from Hadhramaut to Qatar. The name “Shammar Shale” was formerly applied to it.