Distribution of Foraminifera in the Arabian Gulf

• Published in: Micropaleontology 1997, Vol.43 (3), p.253-280
• Main Authors: Cherif, Omar H, Al-Ghadban, Abdul-Nabi, Al-Rifaiy, Ibrahim A
• Format: Article
• Language: English
• Subjects: Ammonia; Arabian Sea; assemblages; biota; Carbonates; Cenozoic; cluster analysis; Coasts; Diversity indices; ecology; Fauna; Foraminifera; Gulfs; Holocene; Indian Ocean; Invertebrata; living taxa; Marine; marine environment; Micropaleontology; modern; nutrients; Persian Gulf; Protista; quantitative analysis; Quaternary; Quaternary geology; Sediments; shelf environment; spatial distribution; Species; Species diversity; statistical analysis
• ISSN: 0026-2803; 1937-2795
• DOI: 10.2307/1485827

Ninety-eight foraminiferal species identified in forty sediment samples collected from different parts of the Arabian Gulf (Persian Gulf) are illustrated and their distribution investigated. The identified foraminiferal fauna of the Gulf consists of 15% Textulariina (agglutinated forms), 37% Miliolina (porcellaneous forms), 0.1% Lagenina, 1% Globigerinina (planktic forms) and 47% Rotaliina (the last mentioned three suborders constituting the hyaline forms). Cluster analysis of quantitative data on the distribution of tests of foraminiferal species in the samples allow us to determine four assemblages, generally corresponding to the major geomorphic provinces of the Gulf: a western Iranian Shallow Shelf assemblage, an assemblage distributed all over the Axial Zone of the Arabian Gulf, a deep water assemblage of the Central Basin of the Gulf extending up to the Strait of Hormuz and an Arabian Shallow Shelf assemblage. The study of the geographical distribution of these assemblages and their relation to major geographical characteristics of the surrounding lands suggests that the nature of the foraminiferal assemblages depends mainly on biotic factors. The fauna of the Iranian Shelf displays a high diversity (average Yule-Simpson diversity index for the assemblage 39.2) as it receives an appreciable amount of nutrients from drainages in the topographically high Iranian hinterland. The fauna of the Arabian Shelf displays relatively low diversities (average Yule-Simpson diversity index for the assemblage 16.1) as the arid Arabian hinterland is practically deprived of active drainage. The foraminiferal fauna of the deepest parts of the investigated localities display low diversities and include appreciable proportions of agglutinated forms. Lowest diversities are observed near the Strait of Hormuz (Yule-Simpson diversity index of 14.9), highest diversities near the mouth of Shatt Al-Arab (Yule-Simpson diversity index of 62.9). This suggests that the amounts of nutrients provided by drainages debouching in a landlocked basin is an important factor determining the constitution of the foraminifera of bottom sediments.