First results on determination of cosmogenic 36Cl in limestone from the Yenicekale Complex in the Hittite capital of Hattusha (Turkey) |
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| Authors: | Naki Akçar Susan Ivy-Ochs Vasily Alfimov ?smail Ö Y?lmaz Andreas Schachner Demir Alt?ner Vural Yavuz Christian Schlüchter |
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| Institution: | 1. University of Bern, Institute of Geological Sciences, Baltzerstrasse 1-3, 3012 Bern, Switzerland;2. Institute of Particle Physics, ETH Hoenggerberg, 8093 Zurich, Switzerland and Department of Geography, University of Zurich, 8057 Zurich, Switzerland;3. Middle East Technical University, Geological Engineering Department, 06531 Ankara, Turkey;4. German Archaeological Institute, Istanbul Department, 34437 Istanbul, Turkey;5. Istanbul Technical University, Faculty of Mines, 80626 Maslak, Istanbul, Turkey |
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| Abstract: | We have measured 36Cl in three rock surfaces of the Yenicekale building complex in Hattusha (Bo?azköy, Turkey). Hattusha was the capital of Hittite Empire which lasted from about 1650/1600 to 1200 BC. At Yenicekale, Hittite masons flattened the summit of an outcropping limestone knoll to form an artificial platform as the foundation for a building. Next they built a circuit wall along the lateral precipices of the flattened bedrock platform. We took one sample from the limestone bedrock platform and two samples from limestone building blocks of the circuit wall for cosmogenic 36Cl analysis. Calculated exposure ages are 20 ± 1 ka for the sample from the bedrock platform and 24 ± 1 ka and 52 ± 2 ka for the circuit wall blocks. These exposure ages are significantly older than the age expected based on the estimated time of construction between 3.2 ka and 3.7 ka. We conclude that the sampled surfaces contain significant inherited cosmogenic 36Cl. We cannot directly determine exposure ages for the building complex based on these three samples. On the other hand we may use the measured concentrations to determine how much of the rock was removed from the platform during flattening. To this end we modeled the variation of 36Cl production with depth at Yenicekale using the results from the bedrock sample. We conclude that the Hittite masons removed only around 3 m from top of the limestone block. This means that the volume of rock removed from the bedrock platform is significantly less than the volume in the circuit wall atop the platform. They did not gain enough rock from this flattening to make the building. In agreement with this, the first results of our detailed microfacies analysis indicate that many of the building blocks are not of the same facies as the underlying limestone and must have been quarried elsewhere. Although we were not able to exposure date the Yenicekale complex due to the presence of inherited 36Cl, our data suggest that Hittite masons excavated (most of) the building stones not at Yenicekale, but in quarries outside of Hattusha and then transported them to the construction site. These quarries have not yet been identified. |
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