REE （Rare Earth Element） signatures in fossil vertebrates from different stratigraphic units are sufficiently distinctive to allow identification of the original unit or location in which fossilization occurred. Our...REE （Rare Earth Element） signatures in fossil vertebrates from different stratigraphic units are sufficiently distinctive to allow identification of the original unit or location in which fossilization occurred. Our field studies at the classic Pleistocene site of Fossil Lake, Oregon, reveal at least nine exposed depositional packages, most separated by disconformities. Bones analyzed from eight of the defined packages have distinctly different REE signatures. By accruing an extensive REE data library, samples with nebulous origin can be compared to this data library to determine the best stratigraphic context of the fossil. The research involves an articulated horse from the Ferruginous Sandstone unit at Fossil Lake. This unit shows subtle lithological changes which may indicate differences in depositional environment. The recovered specimen transected these subtle variations of this unit. Since REE reflect depositional environment this specimen offers a unique opportunity to investigate the possible variations in a signature due to subtle changes in lithology. This was accomplished by collecting bone and sediment material from 1 cm increments. By relating subtle changes in lithology to possible variations in REE signature, this study will offer a better resolution for application of REE signatures to Paleoenvironmental interpretations, fossil provenience and stratigraphic correlation.展开更多
The Lop Nur region, in the east part of Tarim Basin, was an important transportation junction between west and east,north and south Eurasia. However, previous studies on prehistoric human activity have concentrated mo...The Lop Nur region, in the east part of Tarim Basin, was an important transportation junction between west and east,north and south Eurasia. However, previous studies on prehistoric human activity have concentrated mostly on the Bronze Age,whereas that during the Stone Age remains largely unresearched. Here, we present a new direct evidence of human activity in the late Pleistocene, recorded on a grinding stone buried in a lacustrine sediment section of the Lop Nur region. The grain size distribution of the sediment section indicates that the site was probably in the center of a lake with weak hydrodynamic environment. Therefore, the stone artifact can only be carried to here by people instead of river and it was never move as soon as left here. Results of radiocarbon dating, the evident stratigraphic relations between the stone artifact and the sedimentary formation, indicate that the human activity could extend to approximately 13 ka BP. Furthermore, the results of starch-grain and use-wear analyses suggest that ancient humans gathered seeds of Triticeae, roots, and tubers and used the grinding stone to simply process selected plant as plant foodstuffs during this period. It implies that the environmental conditions in the river delta of the Lop Nur were inhabitable during the late Pleistocene.展开更多
文摘REE （Rare Earth Element） signatures in fossil vertebrates from different stratigraphic units are sufficiently distinctive to allow identification of the original unit or location in which fossilization occurred. Our field studies at the classic Pleistocene site of Fossil Lake, Oregon, reveal at least nine exposed depositional packages, most separated by disconformities. Bones analyzed from eight of the defined packages have distinctly different REE signatures. By accruing an extensive REE data library, samples with nebulous origin can be compared to this data library to determine the best stratigraphic context of the fossil. The research involves an articulated horse from the Ferruginous Sandstone unit at Fossil Lake. This unit shows subtle lithological changes which may indicate differences in depositional environment. The recovered specimen transected these subtle variations of this unit. Since REE reflect depositional environment this specimen offers a unique opportunity to investigate the possible variations in a signature due to subtle changes in lithology. This was accomplished by collecting bone and sediment material from 1 cm increments. By relating subtle changes in lithology to possible variations in REE signature, this study will offer a better resolution for application of REE signatures to Paleoenvironmental interpretations, fossil provenience and stratigraphic correlation.
基金supported by the Ministry of Science and Technology of China (Grant No. 2014FY210500)the National Natural Science Foundation of China (Grant No. 41372187)
文摘The Lop Nur region, in the east part of Tarim Basin, was an important transportation junction between west and east,north and south Eurasia. However, previous studies on prehistoric human activity have concentrated mostly on the Bronze Age,whereas that during the Stone Age remains largely unresearched. Here, we present a new direct evidence of human activity in the late Pleistocene, recorded on a grinding stone buried in a lacustrine sediment section of the Lop Nur region. The grain size distribution of the sediment section indicates that the site was probably in the center of a lake with weak hydrodynamic environment. Therefore, the stone artifact can only be carried to here by people instead of river and it was never move as soon as left here. Results of radiocarbon dating, the evident stratigraphic relations between the stone artifact and the sedimentary formation, indicate that the human activity could extend to approximately 13 ka BP. Furthermore, the results of starch-grain and use-wear analyses suggest that ancient humans gathered seeds of Triticeae, roots, and tubers and used the grinding stone to simply process selected plant as plant foodstuffs during this period. It implies that the environmental conditions in the river delta of the Lop Nur were inhabitable during the late Pleistocene.
