Sourcing of the Paleolithic artifacts of Cham-e Souran, Ravand River basin, western part of the Central Zagros

Cham-e souran is located on Ravand basin on the west side of Larini Adjudan village, which is on the east side of Islam Abad, Kermanshah. It includes the wide area and an open site of Paleolithic that is formed on an exposed ophiolite. Compared to the other open sites of the Paleolithic, this site extended to an outdoor area and has a relatively large dispersion of tools. Since source routing of cherts has a very important role in reconstructing cultural and communicative networks in pre-historic times. Source routing of the stone tools in this archaeological site, re-examine some issues of the Paleolithic tool-making technology and its relation with access to mines and stone deposits. Accordingly, the elemental composition of sample 8 by 8 pieces taken from samples of chert stone and natural geological sources to identify their potential and their connections with each other with the method of the Mass Spectroscopy Inductively Coupled Plasma (ICP-MS), sent to the Act labs laboratory in Canada and were analyzed. According to chemical analysis conducted in this study rock samples collected from outcrops Cham-e Souran with the artifacts scattered all over the area, matches the rare elements. This compliance can be seen in river’s cherts as well. The distribution of artifacts in some parts of the riverbank, is much more than the exposed terraces dominated the river. Based on this dispersion pattern, it seems that the easy access and the river stone abundance in this era, has priority compared to other deposits of this study.
The chemical composition of sediments and fine-grained sedimentary rocks is an important factor in the study of source rocks and sedimentary environment of sedimentary rocks (Taylor and McLennan, 1985).
Since the chemical and mineral composition of the used stone as stone tools are similar and comparable to a large extent with sedimentary rocks of the study area, study the chemical composition of the stone tools along with data from other studies, such as petrography, is very useful for source routing of the used natural materials.
In order to study the geological source used for the manufacture of stone tools, small amounts of each sample to less than 74 microns were powdered in Agate mortar. In the next step, soft samples were sent to Act labs Company’s laboratory in Ontario, Canada. In this laboratory, about 25/0 grams of each sample were solved in multi-acid digestion method at 4 acids, including Hydrochloric Acid (HCl), hydrofluoric acid (HF), nitric acid (HNO3) and perchloric acid (HCLO4) and then measured by ICP- MS machine.
To investigate the dispersion pattern of elements and compare the chemical data (trace and rare earth elements) with the average composition of the Earth's crust data, according to the (Taylor and McLennan, 1985) and (Rudnick and Gao 2003), the obtained data from the analysis of studied sample were normalized.
Based on the obtained geochemical evidence, it seems that the stones used in the study of Cham-e Souran’s stone tools, have been taken from mafic-ultramafic deposits of the studied region in the ophiolite territory in the range of Islamabad valleys and Souran’s ophiolite veins of the exposed irregularities and nearby river.
Dispersion pattern of artifacts components and stone tools around the river can be seen in the long journey along the river, indicates that human groups in this region during the Middle Paleolithic stone searching for sources of stone used in tools have picked up their most required stones from Chert riverbed pebbles. Most of the river Cherts samples are respectively in a range of brown, dark red and gray colors.
Based on the chemical analysis conducted in this study, rock samples collected from Cham-e souran’s outcrops and the artifacts parts scattered in the area were consistent in terms of rare elements as well as the matching elements in samples of river chert pebbles too.
The studied artifacts samples in this area in terms of density of chip components were much more in some parts of the riverbank rather than the rest, including exposed terraces overlooking the river.
According to the dispersion pattern seems it was in a priority use in this period rather than other deposits in the study area in terms of easy access and abundant river stone resources.
Yet despite the Harold Dibble Theory (Dibble, 1984) about the lack of resources of the Middle Paleolithic stone in the central Zagros and multiple retouching of tools due to the lack of access to suitable stone resources, it can be said that in fact re-done retouching on Dibble samples in this period were the manifest of special tooling industry in the central Zagros and basically it had nothing to do with the lack of stone resources and afresh retouching of this time tools cannot be connected to the lack of chert stone resources. However, this hypothesis should be studied and test other Paleolithic artifacts collections of the area to be consolidated.