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King Fahd University of Petroleum and Minerals. (Saudi Arabia) (2006)

Comparison of recent and miocene foraminifera from Eastern Saudi Arabia

Al-Enezi, Saleh Ben Sfoog Ben Marzoog

Titre : Comparison of recent and miocene foraminifera from Eastern Saudi Arabia

Auteur : Al-Enezi, Saleh Ben Sfoog Ben Marzoog

Université de soutenance : King Fahd University of Petroleum and Minerals. (Saudi Arabia)

Grade : MSc thesis 2006

Résumé
To improve understanding and interpretation of the Middle Miocene foraminifera. Samples of Recent foraminifera from the near shore Arabian Gulf was examined and compared with similar foraminiferal biocomponents of the Dam Formation carbonates at Jabal Midra Al-Janubi. Eleven samples from the Arabian Gulf and 60 samples from the Dam Formation at Eastern Saudi Arabia were collected and analyzed using standard micropaleontological techniques. A total of 47 species from the Gulf were identified to be Recent origin, consisting of 2 agglutinated, 21 miliolid and 24 rotalid species. The Dam Formation had 51 species, consisting of 3 agglutinated, 37 miliolid and 11 rotalids. The presence of species Borelis melo in the Dam Formation confirms its Middle Miocene age. Analysis of the Arabian Gulf foraminiferal environment revealed that foraminiferal diversity tends to increase with depth but decrease with salinity. Similar trends in the foraminiferal biocomponents at the Dam Formation have been interpreted to provide a new palaeoenvironmental understanding, and similarities of the foraminiferal biofacies of the Middle Miocene and Recent. Results further indicate the foraminiferal fossils at the Dam Formation commenced deposition following a slight marine transgression over an eroded Palaeogene surface during the Middle Miocene, under highly adverse, hypersaline conditions. Successive small-scale marine transgressions, with normal salinity, led to foraminiferal colonization and the accumulation of foraminiferal wackestones, packstones and grainstones. These minor fluctuations led to the development of shoaling-upwards cycles, in which the foraminifera and grain sizes responded to increasing energy conditions as well as slight elevations in salinity, as evidence by the concentrations of hypersaline-tolerant miliolid foraminifera.

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Page publiée le 26 septembre 2010, mise à jour le 9 novembre 2017