Abstract The establishment of the Late Triassic time scale has given rise to considerable controversy, particularly regarding the Rhaetian duration and the inferred absolute age models. In this respect the astronomical polarity time scale (APTS) established from the continental successions of the Newark Basin (eastern North America) is considered as a reference record, although its completeness is questioned. Numerous magnetostratigraphic correlation schemes have been proposed between the APTS and biostratigraphically well-constrained Tethyan marine sections. This has led to two main contrasting options: a “short” Rhaetian duration (about 4–5 myr), and a “long” one (about 8–9 myr). Astronomical calibration of the Tethyan Rhaetian and estimate of its duration is necessary to help advance this debate. We have undertaken a cyclostratigraphic analysis of a Rhaetian composite record built from four overlapping Austrian reference sections. Magnetic susceptibility variations of the 131.5 m thick record are astronomically paced by the precession and 405-kyr orbital eccentricity cycles. 405-kyr orbital tuning allows to establish a floating time scale, and thus to suggest a minimum duration of 6.69 myr of the Rhaetian stage. Given the well-established radioisotopic age of the Rhaetian-Hettangian boundary of 201.36 Ma, an age no younger than 208.05 Ma for the Norian-Rhaetian boundary can be proposed. This result will contribute to the refinement of the Late Triassic time scale, but it does not solve the long-standing debate on bio-magnetostratigraphic correlations between the continental Newark APTS and the Tethyan marine sections, nor the question of the completeness of the Rhaetian Newark Basin.

中文翻译：

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奥地利关键部分的天文定标

摘要 晚三叠世时间尺度的建立引起了相当大的争议，特别是关于雷蒂亚纪年和推断的绝对年龄模型。在这方面，从纽瓦克盆地（北美东部）的大陆序列建立的天文极性时间尺度 (APTS) 被视为参考记录，尽管其完整性受到质疑。已经在 APTS 和生物地层学上受到良好约束的特提斯海洋剖面之间提出了许多磁地层相关方案。这导致了两种主要的对比选择：“短”雷蒂亚持续时间（约 4-5 米）和“长”持续时间（约 8-9 米）。Tethyan Rhaetian 的天文校准及其持续时间的估计对于推动这场辩论是必要的。我们对由四个重叠的奥地利参考剖面构建的雷蒂亚复合记录进行了旋回地层分析。131.5 m 厚记录的磁化率变化在天文上由进动和 405 kyr 轨道偏心率循环决定。405-kyr 轨道调谐允许建立一个浮动时间尺度，因此建议雷蒂亚阶段的最小持续时间为 6.69 myr。鉴于已确定的 Rhaetian-Hettangian 边界的放射性同位素年龄为 201.36 Ma，可以提出 Norian-Rhaetian 边界的年龄不小于 208.05 Ma。这一结果将有助于对晚三叠世时间尺度的细化，但它并没有解决关于大陆纽瓦克 APTS 和特提斯海洋剖面之间生物地磁地层相关性的长期争论，