Bitumens from Tell Yarmuth (Israel) from 2800 BCE to 1100 BCE: A unique case history for the study of degradation effects on the Dead Sea bitumen. (June 2022)

• Record Type: Journal Article
• Authors: Connan, Jacques; Adelsberger, Katherine A.; Engel, Michael H.; Zumberge, Alex
• Is Part Of: Organic geochemistry. Volume 168(2022)
• Publication Date: 2022-06
• Subjects: Dead Sea bitumen -- Biodegradation -- Oxidation -- Steranes -- Terpanes -- Isotopes (CHN) -- Phenanthrenes -- Dibenzothiophenes -- Aromatic steroids; Organic geochemistry -- Periodicals; Biogeochemistry -- Periodicals; Géochimie organique -- Périodiques; 553.205
• DOI: 10.1016/j.orggeochem.2022.104392
• Languages: English
• ISSNs: 0146-6380

Abstract

Highlights: Archaeological samples from the Early Bronze to Iron Age Ia from Tell Yarmuth (Israel) were selected for a geochemical study. Samples may be allocated into lumps of pure bitumen and crusts of bitumen on potsherds. All samples are Dead Sea bitumen. Isotopic (C, H, N) and molecular data were affected through weathering. Two main groups are delineated: lumps of pure bitumen which are slightly altered and crusts of bitumen on potsherds which are degraded to various extends. Abstract: Twenty-one archaeological samples (2800 BCE-1100 BCE) from Tell Yarmuth (Israel) and two samples (700–800 BCE) from Tall Dhiban (Jordan) were analyzed by geochemical techniques. Dead Sea bitumen was identified in all samples. The sample set affords a unique opportunity to study the effects of weathering on Dead Sea bitumen. Lumps of pure bitumen were compared to bitumens which coat the interior face of potsherds. Bitumen on potsherds was recognized as more altered than lumps of pure bitumen. Saturates of potsherd bitumens were enriched in both 2 H and 13 C. Resins and asphaltenes were depleted in 2 H. Resin was the only fraction depleted in 13 C. The δ 13 C of asphaltenes was almost unchanged: −29.3 ± 0.07 (‰/VPDB) compared to an average −29.3 ± 0.16 (‰/VPDB) for present day Dead Sea asphalt. This stability confirms the δ 13 C of asphaltenes as a reliable parameter for tracing the sources of archaeological bitumens. Both resins and asphaltenes were enriched in 15 N. Biodegradation and oxidation proceed through the cleavage of the N-C bond with preferential removal of 14 N. Steranes and terpanes were also affected by degradation. C27 steranes were preferentially removed. C30 αβ hopane was degraded. 18α-22, 29, 30-trisnorneohopane (Ts) /17α-22, 29, 30-trisnorhopane (Tm) and Gammacerane/C31 αβHopane ratios increased due to the selective biodegradation of the αβ hopane family. Significant changes were recorded among phenanthrenes, dibenzothiophenes and also in triaromatic steroids.