الملخص الإنجليزي
A chemostratigraphic curve has been established for the Middle Cretaceous Albian to Turonian argillaceous/carbonate sequences of the eastern Arabian Plate. The curve consists of more than 550 δ13C values from outcrop and subsurface data. It is anchored by biostratigraphy and compares favorable with the character of well dated and published curves from the northern tethys realm. Major trends in the isotope profile can be correlated with major oceanic anoxic events (OAE1b, OAE2) as well as some minor events (e.g. Albian/Cenomanian boundary, Mid-Cenomanian event). The correlation suggests an Albian age for the base Natih Fm. with the Albian/Cenomanian boundary coinciding with the top Natit F unit. The Natih C/D sequence is associated with the Mid-Cenomanian carbon isotope event. While the Natih Fm in the Oman Mountains reaches into the Turonian based on biostratigraphy this level is not reached in the subsurface. This is due most likely to erosion on a fore deep bulge prior to deposition of the overlying Fiqa shales. The stratigraphic tie-points provide an excellent insight into rate of deposition and pace of platform development.
