A significant portion of the upper Eocene deposits in southern Iran primarily consists of limestones, forming what is known as the Jahrum Formation. This formation serves as a reservoir rock in the Zagros Basin, containing numerous hydrocarbon-bearing intervals. The benthic foraminifera are valuable indicators for controlling facies and are abundant in the Jahrum deposits. In this study, by investigating a total of 344.5 meters of the Jahrum succession in the studied well, the distribution of various skeletal grains including benthic foraminifera, algae, bryozoans, and echinoid fragments was determined. The results revealed that the depositional environment of the Jahrum Formation is a homoclinal ramp with three distinct facies belts: lagoon, shoals, and open marine. In addition, within these paleoenvironments the discernible presence of the family Nummulitidae is significant. The nummulitid genera with flattened tests in association with red algae, echinoids, and bryozoans belong to the open marine environment with normal salinity. On the other hand, the miliolids with packstone to grainstone texture formed the shoals, and the absence of nummulitids and the abundance of porcelaneous foraminifera suggest a lagoonal environment with high salinity. Facies analysis has led to the recognition of four depositional sequences, confirming the age of the formation as Priabonian. Finally, considering the biotic relationship among three groups of taxa—algae, bryozoans, and echinoids—with Nummulitidae, Hauerinidae, Rotalidae, and Soritacea (Peneroplidae and Soritidae), their morphological features, and relative distribution, we construct a paleoenvironmental model for the upper Eocene.
Files
You are not registered as a current subscriber. If your institution has an active subscription, contact us to ask for help with your computer's IP address. If you have an active personal subscription, log in.
Subscribe to Micropaleontology
Online only | Added print | |
---|---|---|
Institutions | $700 | $850 |
Individuals | $350 | $500 |