EARTHTIME III: Proof of Concept

EARTHTIME III：概念的验证在过去的一年里，由美国国家科学基金会资助的EARTHTIME项目在联合地质年代学团体和努力实现建立高时间精度的地球历史记录的共同目标方面取得了重大进展。应用这些技术来确定精确的绝对年龄有很大的潜力，因此可以获得以前无法获得的对地质过程、生物进化、气候变化和海洋环流模式的深入了解。现代实验室现在可以确定40Ar/39Ar和U-Pb年龄，精确度优于0.1%。然而，鉴于显著改进的分析，实验室间和衰变方案间的差异现在显然是明显的，在某些情况下超过1%，例如中古生代的数百万年。在比较使用这两个系统获得的日期时，这些差异可能导致重大不确定性，进而可能导致不正确的地质推断，例如，灭绝事件与地质事件或火流星撞击的潜在联系。EARTHTIME项目目前正在组织地质年代学团体消除实验室间偏差和减少系统误差，方法是：1)制定一套标准化的分析规程；2)建立一套广泛商定的矿物和同位素标准，用于实验室间比较；这种方法将能够全面评估衰变方案偏差，并使U-铅和40Ar/39 Argechronology能够自信地结合起来，用于校准地质时间刻度。目前的研讨会将汇集这一领域的著名科学家：1)评估不同系统(例如，陆地与海洋)和不同分支中的演化速率如何随时间变化；2)确定与重大气候事件和对全球深部化学循环的扰动有关的变化率；3)确定深部时间的周期模式是否受天文周期控制；是否可以识别强迫周期；以及如何将天文控制的旋回地层学与其他技术相结合，以提高地质时间尺度的时间分辨率。4)改进磁性地层学和化学地层学记录的校准。5)探索整合地质年代学和生物地层学的新方法。这一建议对国际地球科学界具有广泛的影响。地质时间是我们科学的核心，我们现在有能力以前所未有的分辨率研究地球历史的主要时期。

EARTHTIME III: Proof of ConceptSamuel BowringMITEAR-0637303ABSTRACTIn the past year, EARTHTIME project, funded by NSF, has made significant strides towards uniting the geochronological communities and working towards a common goal of establishing a record of earth history of high temporal precision. 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, biological evolution, climate change, and ocean circulation patterns.Modern laboratories can now determine both 40Ar/39Ar and U-Pb dates to better than0.1% precision. 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. The EARTHTIME project is currently organizing the geochronological community to eliminate interlaboratory bias and reduce systematic errors by: 1) developing a standardized set of analytical protocols; and 2) establishing a widely agreed upon set of mineral and isotopic standards for interlaboratory comparison; such an approach will permit the full evaluation of interdecay-scheme bias and allow for the confident integration of U-Pb and 40Ar/39Argeochronology applied to the calibration of the geological timescale. The current workshop will bring together noted scientists in this area: 1) To evaluate how evolutionary rates vary through time, in different systems (e.g., terrestrial versus marine) and in different clades.2) To determine the rates of change associated with major climatic events and perturbations to global geochemical cycles in deep time.3) To determine whether cyclical patterns in deep time are controlled by astronomical cycles; whether the forcing cycles can be identified; and how astronomically controlled cyclostratigraphy can be integrated with other techniques to improve the temporal resolution of the geologic time scale.4) To improve the calibration of the magnetostratigraphic and chemostratigraphic records.5) To explore new methods of integrating geochronology and biostratigraphy.This proposal has broad implications for the international Earth Sciences community.Geological time is central to our science and we now have the capability to examine major periods of earth history with unprecedented resolution.