Writers : Majidifard, M.R.
Refference : Geosciences Scientific Quarterly Journal,No.:20,P.:2
Publishing Year : 1375

Abstract :
There are adequate outcrops belonging to early Cretaceous rocks in the northern foothill of Shirkuh Lying within the Southwest yazd.
In this area,thinbedded to thickbedded Rudist-Orbitolina bearing limestones (Taft Fm.,aged,Barm.-Apt.) constitutes a major portion of Cretaceous Period.The latter Nonconformity overlies Shirkuh Granite (With an approximate age of 175 m.y.ago ),i.e.,several meters of grey,fine, gained conglomerate as well as red sandstone(Sangestan Fm.)overlies the Granite. Above Orbitolina limestones there is a succession of olive-green shales and yellowish grey, glauconitic many limestone (Darreh-zanjir shales)of Albian age. Darreh, zanjir shales contains so abundant macrofossils among which are Ammonites, Gastropods, Corals, Bivalves, Belemnites and fish teeth. Within the above-mentioned shales,2 Ammonite horizons and 5 Ammonite Zones have been recognized as well.
The influences of the middle Kimmerian movements in the area is well evident from the extant evidences, including Shirkuh Granite, metamorphism of the lower Jurassic Rocks and the unconformity between lower Jurassic and lower Cretaceous Rocks.
By Studying the thin sections and identifying the sedimentary microfacies, three sedimentary environments have been recognized, including open marine, Barrier and lagoonal conditions respectively.
Subject List : biostratigraphy