Abstract
Early carboniferous deposits of the Kalmard block, with various characteristics in different outcrops, are recognized by Gachal Formation. Generally speaking, this formation comprises of four different members (A, B, C and D), consisting of carbonate and evaporative rocks. Gachal Formation is composed chiefly of 55 meters sandstone and limestone interbedded with shale. According to the lithological and microscopic studies, Gachal Formation is deposited in beach, semi-restricted and open lagoon, shoal and open marine environments. Vertical changes of microfacies and the curve of its depth changes account for the high thickness of the facies of shoal and bar sub-environments and the low thickness of the facies of lagoon and open marine sub-environment as well. Gachal Formation rocks in Rahdar section are deposited in a low-angle homoclinal ramp located in southern Paleothysis Ocean. The carbonate-sandstone sequence in Gachal Formation in Rahdar section is composed of a depositional sequence separated from each other by type 1 sequence boundaries. Deposits of this formation are separated from lower deposits by type 2 sequence boundary and from Khan Group by unconformity. The sedimentary sequence identified in this formation points to the age of late Visean, conforming to Kaskaskia IV. The erosional boundary between Gachal and Khan Formations is relatively compatible with drop in sea level at Late Kaskaskia global scale.
Highlights
Central Iran, shaped like a triangle and as one of the major, largest and most complex geological units in Iran, is located in the center of Iran [1]
The mentioned section is located in the southwestern Tabas and east western Robatkhan in Kalmard Block [2]
A2: Quartzarenite, Planar Cross-Bedded Sandstone Presence of 90% Quartz with weak sorting and semi-circular grains in 0.6 mm size is of this microfacies features, that this microfacies belongs to thick bedded sandstones in brown color in Gachal Formation Pressure curve which is of processes during sedimentation and after it, is seen in these microfacies
Summary
Central Iran, shaped like a triangle and as one of the major, largest and most complex geological units in Iran, is located in the center of Iran [1]. The carboniferous carbonate rocks of this block are distinct from others due to having an evaporative member (the member C of Gachal Formation). The mentioned section is located in the southwestern Tabas (at 1:250,000 scale) and east western Robatkhan (at 1:100,000 scale) in Kalmard Block (eastern central Iran) [2]. This section is framed by the geographical coordinates of 33 ̊16'05"N and 56 ̊09'28"E. Rahdar section is located about 65 kilometers from Tabas-Yazd main road, accessible by a two-kilometer-dirt road (Figure 1).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
