Taxonomy and palaeoenvironments of Middle and Late Jurassic foraminifera and its associations of Saudi Arabia.
Doctoral thesis, UCL (University College London).
The recent studies of the high-resolution depositional cyclicity of the Saudi Jurassic carbonates have revealed the stratigraphically and biostratigraphically complexity that mainly result from relative sea-level changes. Studying the environmental sensitivity of benthic foraminifera, associated microfossils and macrofossils has provided a potentially valuable technique for determining subtle variations in the depositional environment and also provide a proxy for sea-level fluctuations. Middle and Late Jurassic carbonates of Saudi Arabia were deposited on a very extensive shallow submarine platform that extended over most of the Arabian Plate. Dhruma, Tuwaiq Mountain Limestone and Hanifa Formations are included in this study. The assigned age for the Middle Dhruma Formation is Late Bathonian to Middle Callovian age for the Upper Dhruma Formation. The Lower Tuwaiq Mountain Limestone Formation is of the Middle Callovian age and Late Callovian is assigned for the Middle and Upper Tuwaiq Mountain Limestone Formation. Early to Middle Oxfordian is dated for the Lower Hanifa Formation and Late Oxfordian-Early Kimmeridgian for the Upper Hanifa Formation. This study is based on semi-quantitative micropalaeontological analysis of closely-spaced thin sections from subsurface and outcrop localities. The subsurface samples are from four carbonates reservoirs in eastern Saudi Arabia and one stratigraphic well in central Saudi Arabia near the type area of the studied formations. The outcrop samples are from age-equivalent outcrops of these reservoirs in central Saudi Arabia, near their formations type area. Reviewing and improving the existing Middle and Upper Jurassic benthonic foraminiferal taxonomy have been achieved in this study. About sixty biozones and seven biofacies have been established for the whole studied localities. These biozones and biofacies have provided significant contributions towards understanding the stratigraphy and palaeoenvironments of the studied formations from the Middle Dhruma Formation to the uppermost Hanifa Formation in both outcrop and subsurface localities.
|Title:||Taxonomy and palaeoenvironments of Middle and Late Jurassic foraminifera and its associations of Saudi Arabia|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences|
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