STUMP, T. E., T. C. CONNALLY, and J. G. L. A. VAN DER EEM, Saudi Aramco, Dhahran, Saudi Arabia

ABSTRACT: Major Events in the Late Precambrian to Early Triassic Geohistory of the Arabian Peninsula

The late Precambrian to Early Triassic of the Arabian Peninsula occur in five supergroups. Their geohistory resulted from sedimentation along fluvial to midshelf facies tracts, eustatic oscillation, and periodic uplift.

The first supergroup, ?late Precambrian-Middle Cambrian, includes the Siq/Salib and Yatib formations. Deposited by northeastward-flowing braided streams, they eroded and buried an Arabian shield topography. The Saq Formation lies in angular unconformity on the Siq, which documents early Middle Cambrian uplift.

Supergroup two, Middle Cambrian-middle Caradocian, includes the Burj and Saq formations, the Hanadir, Kahfah, and Ra'an members, Qasim Formation. They were deposited on a stable continental margin in fluvio-deltaic to midshelf settings. Coastal onlap occurred in the Middle Cambrian, early Llanvirn, middle Llandeilo, and early Caradoc. Middle Caradocian uplift deeply eroded parts of central and southern Arabia.

Supergroup three of middle Caradocian-early Llandoverian includes the Quwarah Member, Qasim Formation, newly recognized central Arabian units, and the Zarqa/Sarah formations. They were deposited in fluvio-deltaic shallow shelf settings. Late Ashgill uplift, combined with glacially induced sea level lowering, incised valleys up to 2000 ft (610 m) deep.

Supergroup four, early Llandovery-Middle Carboniferous, includes the Qalibah, Tawil, Jauf, Jubah and Berwath formations. They were deposited in a fluvio-deltaic marine, river dominated system. The Qusaiba and Sharawra members, Qalibah Formation, were the offshore clays and prodelta sands; the Tawil-Jubah were the fluvial to delta front, and the Berwath the delta plain facies. Deep pre-Tawil erosion documents Late Silurian-Early Devonian uplift. Middle Devonian crustal extension and Late Devonian basaltic intrusions were early phases of the Middle Late Carboniferous Hercynian orogeny.

The fifth supergroup includes the Juwayl, Unayzah, Khuff and Sudair formations. The first two units were deposited in a glacio-fluvial system, which eroded and infilled a Hercynian topography. The Khuff transgression occurred during the Artinsklan-Tartarian, while the Early Triassic regressive Sudair documents renewed uplift.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.