Workshop: High-precision Intercalibration of U-Pb and Ar-Ar Geochronometers

在过去的五年中，40Ar/39Ar和U-Pb地质年代学的精度稳步提高，最近的进展可能使我们能够解决以前无法解决的问题。这些技术在确定精确的绝对年龄方面具有很大的应用潜力，从而对地质过程的速率产生以前无法获得的见解，并发展出完全一致、可靠和高度确定的地质时间标度。现在在现代实验室中，在不考虑外部误差来源的情况下，确定40Ar/39Ar和U-Pb日期的精度为0.1%或更好。然而，由于分析的显著改进，实验室间和衰变方案间的差异现在非常明显，在某些情况下超过1%，例如中古生代的几百万年。在比较使用两种系统获得的日期时，这些差异可能导致重大的不确定性，进而可能导致不正确的地质推断，例如将灭绝事件与地质事件或火流星撞击联系起来。该奖项将资助于2004年10月15日或22日在麻省理工学院举行的为期两天的研讨会，届时将汇集全球主要实验室的代表，他们将参与40Ar/39Ar和U-Pb地质年代学，讨论实验室间差异的问题和解决方案，并进一步制定一项计划，以提高地质年代学的精度和准确性。这将包括让参与者在本次会议上分析和报告U-Pb和40Ar/39Ar标准数据。U-Pb和40Ar/39Ar社区在本次研讨会上的加入将为集中精力理解和解决衰变系统间偏差问题提供基础，并允许两种计时器自信地应用于地质时间标度的校准

EAR-0443866BowringIn the past five years, the precision of both 40Ar/39Ar and U-Pb geochronology has steadily improved with recent advances potentially allowing us to address questions previously out of reach. There is great potential for the application of these techniques to determining accurate and precise absolute ages thus yielding previously unattainable insights into rates of geological processes and the development of a fully consistent, robust and highly resolved geological timescale. It is now common in modern laboratories to determine both 40Ar/39Ar and U-Pb dates to 0.1% precision or better when not considering external sources of error. However, given the significantly improved analysis, interlaboratory and inter-decay-scheme differences are now clearly apparent, in some cases being more than 1%, e.g., several million years in the mid-Paleozoic. These discrepancies can lead to major uncertainties when comparing dates obtained using the two systems, which in turn can lead to incorrect geological inferences, for example the potential linking of extinction events with geological events or bolide impacts.This award will fund a two-day workshop to be held at MIT the weekend of October 15th or 22nd 2004 that will bring together representatives of the major laboratories worldwide involved in both 40Ar/39Ar and U-Pb geochronology to discuss problems and solutions to interlaboratory differences and to develop further a plan to move forward with increased precision and accuracy in geochronology. This will include having participants analyze and report both U-Pb and 40Ar/39Ar standard data at this meeting. The joining of both the U-Pb and 40Ar/39Ar communities at this workshop will provide a foundation for a focused effort toward understanding and resolving the issue of inter-decay system bias and allowing confident application of both chronometers to the calibration of the geological timescale.***