A 3500-YEAR MASTER TREE-RING DATING CHRONOLOGY FROM THE NORTHEASTERN PART OF THE QAIDAM BASIN
柴达木盆地东北部3500年树轮定年年表的初步建立*

A master ring-width dating chronology for the last 3500 years was developed by cross-dating well-replicated samples from different sources at 26 sites distributed over a region almost 200km across in the northeastern part of the Qaidam Basin in Northwestern China. The materials came from living trees, dead trees still standing on the slopes, and archaeological woods such as trunks and wooden coffins from the tombs of the Tang Dynasty situated on the alluvial fans in the study area. The longest core from living trees was dated back to 404A.D. , and the time span covered by the archaeological woods is from 1580BC to 793A.D. The specimens from the dead trees covered the period of A.D. 130 to 1794. The overlaps in time among the three types of samples are long enough to support the development of a high-quality long chronology for the study area. We found that cross-dating could be performed well among specimens of different sources and highly significant correlation coefficients were present among three types of samples for their overlaping periods, i.e. , 0.51 between the archaeological woods and dead trees, 0.41 between the dead and living trees, and 0.61 between the archaeological woods and living trees, respectively. This suggests that it is possible to establish a master chronology for the study area. Using the master dating series produced by the program COFECHA for each site of the living trees, for all the dated archaeological woods and specimens from dead trees, a master dating chronology using specimens from 621 trees from the study area was developed by COFECHA again. This long chronology is not only independent of the published Dulan chronology, but also more than 1000 years longer, reaching to the time of Shang and Zhou Dynasties. After two missing rings were added to the Dulan chronology, these two chronologies are cross-dated very well for the common period of 328BC~2000A.D. This is by far the longest tree ring dating chronology in China, which can be used as a reference for ring-width dating for trees from the arid and semi-arid regions of Northwest China.