Project- Geology
An Introduction to the Chahan Twin Anticline Study Area
The study area is located in the southeastern part of Iran, in the Makran Accretionary Wedge, southwest of Nikshahr. The Makran Accretionary Wedge is divided into four domains based on new stratigraphic-tectonic data, which are separated by major thrusts. These domains, from north to south, are named the North Makran, Inner Makran, Outer Makran, and Coastal Makran.
A simplified map of the Makran Accretionary Wedge based on new stratigraphic-tectonic data shows that the North Makran is mainly composed of Cretaceous rocks, the Inner Makran is mainly composed of Eocene to Middle Miocene rocks, the Outer Makran is mainly composed of Upper Oligocene to Middle Miocene rocks, and the Coastal Makran is mainly composed of Upper Miocene and Pliocene-Pleistocene sediments.
An introduction to the study area (Chahan Twin Syncline)
- Folding in these rock units is observed as very long wavelengths (more than 10 km), gentle and rounded folds.
- The wavelength of the anticlines in these units, especially when the marl is exposed, is much less reaches to 1 km.
General view from the long-wavelength synclines in Upper Miocene sediments located in northwest Chabahar
What is syncline?
Syncline, is a folding in rock units that means the layers dip towards each other. Syncline is a Persian word that points out to the bottom of the ship. Longitudinal valleys and depressions may be considered a type of syncline.
Geological Map of the Study Area (Based on Maps on Scale 1:100.000)
Patanpiss syncline, with approximate height of 900m above sea level, is one of the highest peaks in the mountainous part of Bandini sheet that is located in the north of the study area. These elevations are mostly composed of sandstone and conglomerate units as hard formations and forms the rough geomorphology of the region.
In addition, in those parts of the syncline where block-bearing flysch is exposed, it is observed as sharp cones in the lowlands due to the difference in the blocks composition (hard igneous and sedimentary rocks such as limestone and sandstone) with the host rock (erodible shale and marl).
Patanpiss has a double-plunged relatively regular and lengthy structure with moderate folding. It is a asymmetrical structure with more slope on its northern flank that may be caused due to the difference in the rock type as well as changing facies of the northern and southern rock units.