A comparative geochemical study of bituminous boat remains from H3, As-Sabiyah (Kuwait), and RJ-2, Ra's al-Jinz (Oman)

This paper presents a geochemical analysis of fragments of bituminous amalgam from H3, As‐Sabiyah (Kuwait), and RJ‐2, Ra's al‐Jinz (Oman). The fragments bear barnacles on one side and reed impressions on the other, and are thought to have been part of the coating of reed‐bundle boats. The material from H3 dates to between 5300–4900 BC, while that of RJ‐2 dates to 2500–2100 BC. Samples from both sites were geochemically compared to archaeological and ethnographic material from Kosak Shamali (northern Syria, c.5000–4400 BC), RH‐5 (Oman, 4400–3500 BC) and Baghdad (central Iraq, 1900 AD). The composition of the bituminous amalgams was studied in detail. Rock‐Eval Pyrolysis gave a measure of Total Organic Carbon in the samples, and allowed an initial comparison of the data sets using various parameters. Examination of the proportions of soluble and insoluble organic matter allowed an assessment of the quantity of vegetal matter added to the bitumen to make the bituminous amalgam. The composition of the Ra's al‐Jinz material was studied using X‐Ray Diffraction analysis and thin‐section petrography, in order to assess the proportions of various minerals in the bituminous amalgams. It was concluded that the recipe for the bituminous mixture used to coat reed‐bundle and wooden boats did not differ significantly from that commonly used to make ‘mortar’ for architectural purposes in Mesopotamia. Traces of animal fats or fish oils were not found in the analysed Ra's al‐Jinz material, in contrast to previous hypotheses regarding the composition of the mixture. Comparison of the gross composition of extractable organic matter (the constituents of pure bitumen, soluble in chloroform or dichloromethane) showed the progressive effects of weathering on the samples. The isotopic composition of the bituminous material from H3 and the other sites was then compared to that of bitumen seeps and crude oils from Mesopotamia, Iran and Oman. The most significant result is that the material from As‐Sabiyah originated in Kuwait, at a surface seep at Burgan, while the material from Ra's al‐Jinz had a source in northern Mesopotamia.