Early Holocene Dendrochronology and Calibration of 14C Dating

亚利桑那大学树木年轮研究实验室的树木年代学家，从加利福尼亚东部的一个地方建立了从现在到公元前6700年的连续的硬尾松年轮年表，这些树木的木材被用来校准公元前6450年的历年放射性碳时间尺度。将尝试将现在追溯到公元前9500年的树木年轮年表的不连续部分联系起来，或者，从整个全新世一直到晚冰期早于公元前6450年的样品将在美国国家科学基金会-亚利桑那大学加速器质谱仪设施中用于进一步的放射性碳校准。这具有相当大的科学意义，因为这个数据集是目前唯一一个，并且在一段时间内，为基于欧洲橡木和松树的类似放射性碳校准提供真正的年度分辨率的数据集。然而，橡树和松树之间的时间重叠并不是基于树木年轮的交叉定年，而是基于8750 B.P.附近放射性碳活动的匹配模式。目前掌握的几个狐尾松系列是14C的，可以追溯到全新世早期。其中一个似乎很有可能验证欧洲工作中所依赖的放射性碳活动模式。这项跨学科的工作很重要，因为它使测量许多全球环境过程的变化率的准确性达到了新的水平。通过其他类型的分析，木材本身可以提供有关气候和其他环境参数的性质和变化范围的新信息。

Dendrochronologists at the Laboratory of Tree-Ring Research, University of Arizona, have established a continuous bristlecone pine tree-ring chronology from one locality in eastern California that reaches from the present back to 6700 B.C. Wood from the trees has been used to calibrate the radiocarbon time scale in calendrical years back to 6450 B.C. An attempt will be made to connect discontinuous segments of the tree-ring chronology that now reach back to about 9500 B.C., or, through the entire Holocene into Late Glacial times. Samples dating earlier than 6450 B.C. will be used for further radiocarbon calibration at the NSF-University of Arizona Accelerator Mass Spectrometer facility. This is of considerable scientific interest because this data set is the only one that might now, and for some time, provide truly annual resolution for independent verification of a similar radiocarbon calibration based on European oak and pine. The temporal overlap between the oak and pine is not however based on tree-ring cross- dating, but on matching patterns of radiocarbon activity near 8750 B.P. Several bristlecone pine series now in hand are 14C dated to the early Holocene. One appears to have high potential for verifying the pattern of radiocarbon activity relied upon in the European work. This interdisciplinary work is important because it permits new levels of accuracy in measurement of the rates of change in many global environmental processes. The wood itself, through other kinds of analyses, can provide new information on the nature and range of variation in climatic and other environmental parameters.