مطالعات آزمایشگاهی برروی معدن سنگ باستانی کوه چل‌مران کنگاور و مقایسۀ آن با سنگ‌های معبد آناهیتا کنگاور

شناسایی منابع و معادن جهت استخراج و استحصال مواد اولیه در دنیای باستان، موضوعی جالب توجه است. نتایج حاصل از مطالعه و شناسایی معادن باستانی می تواند منجر به شناخت بهتر فناوری تولید مواد و ابزار در دنیای باستان توسط متخصصان باستان سنجی شود و نشان دهد که هنرمندان و صنعتگران دنیای باستان چگونه سعی در استفاده از مواد خام جهت تولید اشیاء مختلف روزمره و آثار هنری می کرده اند. ازسوی دیگر، شناسایی معادن باستانی می تواند در برخی موارد (مانند آثار سنگی) مواد اولیۀ مناسب را جهت بازسازی آثار در اختیار مرمتگران آثار تاریخی قرار دهد. در این مقاله، سنگ های به کار رفته در معبد آناهیتا کنگاور و معدن باستانی کوه چل مران با استفاده از روش های آزمایشگاهی مطالعه شده اند. هدف از این پژوهش، شناسایی ترکیب شیمیایی و ساختاری سنگ های به کار رفته در معبد آناهیتا و ارتباط آن ها با شواهد معدن کاری باستانی در کوه چل مران است. به این منظور نمونه های سنگ معبد آناهیتا و معدن چل مران با استفاده از روش فلوئورسانس اشعۀ ایکس و پتروگرافی مقطع نازک آزمایش شده اند. پرسش اصلی پژوهش این است که با استفاده از مطالطعات آزمایشگاهی (در کنار یافته های باستان شناسی) می توان رابطۀ دقیق تری بین معدن سنگ چل مران و آثار سنگی محوطۀ معبد آناهیتا کنگاور مشاهده نمود؟ نتایج نشان داد که سنگ های معبد آناهیتا و معدن چل مران، هردو از نوع سنگ آهک هستند و عناصری مانند سیلیسیوم و منیزیوم تنها به عنوان عناصر فرعی و به میزان کم در ترکیب نمونه ها وجود دارند. ساختار میکروسکوپی سنگ ها شامل فاز کلسیت همراه با ناخالصی های دولومیت و کانی های رُسی است. براساس نتایج، معدن کوه چل مران به عنوان منبع مهم تولید قطعات سنگ در ساخت معبد آناهیتا مورد استفاده قرار گرفته است.

Analytical Studıes on the Chel Maran Ancient Stone Quarry and Comparison with the Stones of Anahita Temple of Kangavar

AbstractIdentification of resources and quarries used for extraction of raw materials in the ancient time is a very interesting subject matter for researchers and archaeologists. Results of analysis and study of ancient mines and quarries may lead to characterize the know how of ancient technology of production of materials and tools in the old world and shows the techniques rendered by artists and craftsmen to apply raw materials for producing different artistic and ordinary objects. Moreover, identification of ancient mines and quarries (especially stone quarries) provide unaltered materials for conservators to reconstruct archaeological and historical stone monuments. In this paper, stone blocks used in Anahita Temple in Kangavar and ancient stone quarry of Chel Maran (Chehel Maran) were studied by analytical methods. The aim of this study is to determine chemical composition and microstructure of stones used in the Anahita Temple and their correlation with the stone mining evidences observed in the Chel Maran quarry. For this purpose, some samples from the temple and the quarry were analyzed by Xray fluorescence and polarized optical microscopy methods. The results indicated that the stones used in the temple and those of the quarry are limestones and Si and Mg were identified in the analysed samples as minor constituents. Microscopic structure of samples presented calcite as the main phase including some dolomite crystals and clay minerals as impurities. Based on the results obtained, the Chel Maran ancient stone quarry was widely used for the construction of the Anahita Temple. Keywords: Ancient Mining, Anahita Temple of Kangavar, Chel Maran Quarry, Limestone, Calcite.IntroductionStone has been used widely during the ancient time to make different artefacts and monuments including small ritual and decorative objects, reliefs, decorative monuments and buildings. The studies on quarrying and manufacturing of stone objects as well as the provenance of raw materials are an interesting subject in geoarchaeological and archaeometric investigations (Goldberg et al, 2006), and this is a useful study when restoration interventions are required. The large archaeological complex of Anahita Temple is located in western Iran, in the city of Kangavar and based on the archaeological excavations and findings, it was dated from the Achaemenid to the Sasanian periods (Azarnoush, 1981; Kambakhsh Fard, 1994). It was constructed on a natural hill and it was erected by stone and gypsum mortars. The main building was built with large stone blocks including cubic blocks for walls and very large and thick circular columns. There are some evidences of stone quarrying in different areas near the Anahita Temple. The main and important stone quarry in this region is Chel Maran (Chehel Maran) stone quarry located in the west of the Temple in a mountain with the same name (Chel Maran mount) (Oudbashi, 2008). The aim of this paper is to analyse the stones from Anahita Temple and the Chel Maran quarry in order to compare their chemical and microstructural features and to find a possible relationship between the building and the quarry. MethodsFive fragments from the Anahita Temple and two big samples from the Chel Maran quarry were selected. Ten grams of each sample was powdered for chemical analysis. A thin section was prepared from each sample for microscopic studies. The chemical composition of samples was characterized by Xray Fluorescence (XRF) analysis by using a S4 Pioneer model Xray fluorescence spectrometer manufactured by Bruker. Microscopic observation of fragments and stones were done on thin sections by using a Primotech model Zeiss polarized optical microscope. Thin sections were studied by alizarinred method to identify presence of dolomite in the texture of stone samples (Flügel et al., 2010)Findings and ArgumentThe results of XRF analysis of the stone samples are presented in Table 1. The results show that all samples are calcarous stones as can be deduced by the high amount of CaO and the loss on ignition (LOI). Furthermore, SiO2, MgO and Al2O3 were detected as minor constituents in the composition of the stone samples. Other elements were detected as minor/trace content in the compsoition of samples. Although, the stones shows variable amounts of some constituents such as Na2O or Al2O3 , it is visible that the chemical compsoiton of stone samples of the Temple and the quarry is quite similar. The pertographic study showed a layerad texture of micrite to sparite in all samples. There were many veins of secondary calcite in the texture of the samples. Alizarinered test indicated the presence of sporadic dolomite crystals in the texture of the stone samples. Furthermore, some compact clay veins were visible with dark colors in the microstructure of the samples (Bausch, 1968). The compariosn of the petrographic micrographs of samples from the Anahita Temple and the Chel Maran quarry reveals that they are very similar from textural point of view, in particular, sample CM2 that was taken from the western part of the Chel Maran mount, where many evidences of quarrying and stone extraction are visible in that area.ConclusionThe results of chemical and petrographic analysis of the stone samples from the Anahita Temple of Kangavar and the Chel Maran stone quarry showed that the Chel Maran stone quarry was used as a main resource to provide stone blocks for the construction of the Anahita Temple. The analysis indicated that the stone samples can be classified as limestone with some impurities such as SiO2, Al2O3 and MgO that are due to presence of clay minerals and dolomite in the structure of both the stone of the Temple and the quarry. The petrographic studies also showed a micrite to sparite texture with evidences of clay veins and small amounts of dolomite spread in the texture of the stones. The results obtained proved the similarity of the chemistry and the texture of samples from Anahita Temple and the quarry which indicate that the ancient quarry of Chel Maran was one of the source of the stones used in the historic monument of Anahita Temple.