Abstract
Paleozoic successions in Saudi Arabia are exposed around and bordering the south, north, and northeastern edge of the Arabian shield. They are represented by the Wajid group in the south and by the Taymah, Tabuk, Qalibah, Huj, and Buraydah groups in the north and northeast. The Wajid group includes Dibsiyah, Sanamah, Khusayyan, and Juwayl formations. The Taymah group includes Siq, Amai’er, Quweira, Saq, and Qasim formations. The Tabuk group includes Zarqa, Sara, and Hawban formations. The Qalibah group includes Baq’a, Qusaiba, and Sharawra formations. The Huj group includes Tawil, Jauf, and Jubah formations. The Buraydah group includes Berwath, Unayzah, and Khuff formations. The Wajid group form one block in the south and the other groups form another block in the north, and they can be correlated. There are similarities between the northern belt which consists of the Cambro-Ordovician formations of the Tayma and Tabuk groups and the southern belt which consists of the Dibsiyah and Sanama formations of the Wajid group. Similarities include sandstone composition, sedimentary environment, paleocurrent directions, unconformities, tectonic events, and influence of Gondwana glaciations. These formations and probably some or all the rest of the Paleozoic formations used to form one block but later separated after erosion caused by gradual tectonic growth, uplift, and prominence of the Arabian shield. During early Paleozoic time, the process started by poststabilization then sedimentation and at a later stage the growth and uplift of the shield occurred gradually. Growth of shields is a fact and it is the only way to explain the exposure of the Wajid sandstone on top of the highest mountain of the shield which exceeds 3,000 m in As Sawdah in Asir area in southwestern Saudi Arabia. The sandstone sediments of these outcrops were deposited on a low lying basin before been raised to this elevation.