Geoscience studies in solving archaeological problems in the east of Damghan
Fathalizadeh Kosar1, Zarei Elahe2*, Sarfi Mehdi2
1Master of Science, School of Earth Sciences, Damghan University, Damghan, Iran
2Assistant Professor, School of Earth Sciences, Damghan University, Damghan, Iran
Corresponding author (Elahe Zarei) E-mail: ezarei@du.ac.ir


1- Introduction

The results of archaeological investigations show the presence of humans in the northern part of the central desert of Iran since long ago (Vahdati nasab Hamed and Hashemi Milad 2016). The location of ancient settlements, as the settlements of previous humans, is mainly dependent on environmental factors such as water sources. Therefore, in order to determine the presence of water and its expansion, a 13 km long area was studied on the road from Damghan to Shahroud.
2- Material and Methods
Palynology and sedimentology are common and applied methods for paleoenviroment interpertation especially for Neogene and Quaternary sediments. After the field studies, a number of samples were collected from 3 study stations to palynological, sedimentological and microfacies studies. The studied area is located on the border between Alborz structural state and Central Iran, approximately 30 km east of Damghan (coordinates with E 54° 36΄09 ˝ to 54° 45΄37˝ and N 36° 15΄43 ˝ to N 36° 16΄ 26 ˝).
3- Results and discussion
Geological studies
In this research, XRD studies were used to identify the minerals in the region. Also, in order to check the degree of rounding and sorting of the sediments and to identify the mineralogical composition of the samples after sieving, they were studied under the streptomicroscope. The presence of transparent and angular quartzes and unstable minerals such as feldspar and muscovite and the abundance of organic matter in the landform sediments indicate an aquatic environment in which a series of erosion events to sedimentation have taken place in a short period of time.
Based on the presence of some index dinoflagellate species such as Operculodinium cf. eiricianum and Bitectatodinium tepikiense and comparing it with the world standard biozones of Williams et al., 2004, the age range of Late Miocene to Pliocene can be considered for the landform sediments. (Head 1994).
A combination of archaeological and geomorphological data, sedimentology and palynological studies and the presence of Index dinocysts such as Operculodinium cf. eiricianum and Bitectatodinium tepikiense indicate a vast and ancient lake during the Late Neogene (Brenchley1998, Head 1994, Michelle Price, 2010). The presence of ancient settlements confirms this claim.
This relatively vast aqueous environment was related to the Haj Ali Qoli salt playa (Chah Jam playa) in the south of the studied area, and the sediments studied were placed on the northern edge of the lake when the water level was high. Probably, tectonics and climate have influenced the lowering of the water level. Butzer 1958 and Crinsley 1970 report evidence of a lacustrine environment around Central desert of Iran (Butzer, 1958; Krinsley, 1970).
4- Conclusion
The most important issue for archaeologists in the last few decades is the investigation of environmental factors in the formation or destruction of civilizations and human habitats.
One of the most important points for creating human settlements is the presence of water sources close to human settlements. Archaeological research indicates the presence of humans in Damghan region from the past until now. In this regard, the spatial distribution and dispersion of the ancient centers of eastern Damghan and its relationship with environmental factors (water and climate) were investigated. A combination of archaeological, geomorphological and palynological data shows that there was a vast paleolake in the Northern part of the Iranian Central Desert, which is considered a suitable environment for human settlements. The studied sediments were deposited on the clay zone in the northern margin of Damghan playa when the water level was high, which is probably related to Haj Ali Qoli salt lake (Chah Jam playa) in the south of the studied area. The high amount of clay 20 to 45% confirms this environment. The presence of an index dinocyst Bitectatodinium tepikiense shows that there was a paleolake in the northern part of the central Iranian plateau at the end of the Neogene, which was probably connected to the open sea. Probably, two factors, tectonics and climate changes, have influenced the lowering of the water level and made it into its present form.

Key words: geological studies, ancient lake, ancient settlements, East Damghan
Reference:
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- Brenchley, P. J. & Harper, A. T. 1998. Palaeoecology: Ecosystems, Environments and Evolution, 402 pp. Chapman & Hall publ, New York.
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