MIDDLE MIOCENE BRYOZOA FROM SIWA OASIS, WESTERN DESERT, EGYPT

مقال فى مجلة

2000

Forty bryozoan species relating to the orders Cyclostomata and Cheilostomata have been

identified from the Middle Miocene Marmarica Formation in Siwa Oasis. They represent the

most abundant bryozoan species in the studied sections. The whole bryozoan assemblage

includes more than fifty species, all of them are recorded from this locality for the first time

(except four species).

According to their zoarial (=colonial) growth forms, the studied bryofauna are belonging

to the following: erect flexible, erect rigid and encrusting groups: cellariiform, adeoniform,

eschariform, reteporiform, vinculariiform, membraniporiform and celleporiform.

Holoporella polythele and Tretocycloecia dichotoma form a disconnected bryozoan

buildups. Such organic "reefal or at least biohermal" bryozoan record represents environmental

conditions similar to those found in the same stratigraphic horizon in Matruh to the north.

The studied bryozoan assemblage reflects the following paleobiogeographic conditions:

1. Mediterranean affinity of the studied fauna. 2. Monotonous areal conditions allover the

northern Western Desert during the formation of the Marmarica Limestone in the Middle

Miocene. 3. Free and continuos connection with North Africa, from Libya to Morocco. 4.

Limited connection with the north Eastern Desert, Gulf of Suez, Sinai and the Red Sea.

• مجلة/صحيفة: 5th International Conference on the Geology of the Arab World, Cairo University
• الصفحات: 1465-1496