Exploration of diagenetic profiles at mammoth localities on the North American grasslands

As a feasibility study, samples of mammoth bone from four localities across the North American grasslands were analyzed to assess preservation and provide an initial overview of the diagenetic history at each of the different sites. The localities encompassed different landscape settings, climates, and environments from the period ca. 12,300 to 11,100 yr BP (uncalibrated radiocarbon years). A small sample size of 12 bones (three from each locality) was used to provide a preliminary characterization of the diagenetic processes and resulting preservation at each locality. Results indicated two different diagenetic profiles, a Northern Profile and a Southern Profile. Bones from the Northern Profile were well preserved for samples of this age. Little or no alteration was observed in the histological structure, nor in the collagen or mineral phases. Total porosity values, however, ranged from fresh bone values to increases of three times that of fresh cow bone. Bones from the Southern Profile generally were poorly preserved. Mineral and collagen phases had experienced significant diagenetic alteration and total porosity increases are consistent at around two to three times that of fresh bone values. These samples exhibited minimal histological alteration, however, and, in general, their histological structure is better preserved than samples from the Northern Profile. Based on extensive sedimentological studies, the dominant hydrologic regimes at each locality not only shaped the landscape, but also appeared to have played a decisive role in determining the diagenetic histories of the buried mammoth remains. Preliminary results strongly supported the importance of groundwater activity (i.e., presence, absence, and fluctuations) throughout the period of burial in the preservation of the skeletal remains.