Abstract Here we present Re-Os geochronological data from two carbonaceous shale units from the Hornby Bay and Amundsen basins that provide important chronological markers for Mesoproterozoic stratigraphic successions within northern Canada. Shale from the basal Escape Rapids Formation yields a robust depositional age of 1067.3 ± 13.5 Ma for the lowermost Shaler Supergroup of Amundsen basin with a remarkably unradiogenic initial 187Os/188Os value (0.15), implying that it derived from weathering of juvenile source material, such as basalt. Sedimentological features, indicative of large basin conditions, suggest deposition within an extensive epeiric sea that was intermittently mixed with waters from an exterior ocean. This age, and the 720 Ma age of the uppermost Shaler Supergroup, constrain deposition of the ∼4 km-thick succession to a period of approximately 350 myr, recording sedimentation through a complete supercontinent cycle - amalgamation through to break-up of Rodinia. Further, it indicates that the Amundsen basin formed at the same time as the Borden, and Fury and Hecla basins on northern Baffin Island, and the Thule basin in northwestern Greenland, and that these basins were perhaps connected as part of a much larger basin situated in the interior of Rodinia. Diagenetic pyrite from sandstone dykelets in carbonaceous shales of the Fort Confidence Formation yielded a Re-Os model age of 1438 ± 8 Ma, providing a minimum age for deposition of the lower Dismal Lakes Group of the Hornby Bay basin. This age strengthens proposed regional correlation of the Hornby Bay basin with the large intracontinental Athabasca and Thelon basins, located on the Rae craton to the southeast, and is evidence for a Laurentia-wide marine flooding episode ca. 1500 Ma. Both new ages place important constraints on newly discovered eukaryotic microfossils from the Shaler Supergroup and Dismal Lakes Group and calibration points for critical chemostratigraphic data.

中文翻译：

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来自 Hornby Bay 和 Amundsen 盆地的页岩和黄铁矿 Re-Os 年龄为加拿大北部中元古代地层序列提供了新的年代学标记

摘要 在这里，我们展示了来自 Hornby Bay 和 Amundsen 盆地的两个碳质页岩单元的 Re-Os 年代学数据，这些数据为加拿大北部中元古代地层序列提供了重要的年代学标记。对于阿蒙森盆地最下层的页岩超群，来自基底逃逸急流组的页岩产生了 1067.3 ± 13.5 Ma 的稳健沉积年龄，具有显着的非放射性初始 187Os/188Os 值 (0.15)，这意味着它源自幼年源材料的风化，例如作为玄武岩。沉积学特征表明大盆地条件，表明在广阔的表层海中沉积，间歇性地与外部海洋的水混合。这个年龄，以及最上层Shaler Supergroup的720 Ma年龄，将约 4 公里厚的连续沉积限制在大约 350 米的时期，记录通过完整的超大陆循环的沉积 - 合并直至罗迪尼亚的分裂。此外，这表明阿蒙森盆地与巴芬岛北部的博登盆地、弗瑞盆地和赫克拉盆地以及格陵兰岛西北部的图勒盆地同时形成，这些盆地可能作为一个更大的盆地的一部分相连在罗迪尼亚的内部。来自 Fort Confidence 组碳质页岩中砂岩岩脉的成岩黄铁矿产生了 1438 ± 8 Ma 的 Re-Os 模型年龄，为 Hornby Bay 盆地下游 Dismal Lakes Group 的沉积提供了最低年龄。这个时代加强了霍恩比湾盆地与位于东南 Rae 克拉通的大型大陆内阿萨巴斯卡和塞隆盆地的区域关联，并且是 Laurentia 范围内海洋洪水事件的证据。1500 马。这两个新时代都对来自 Shaler Supergroup 和 Dismal Lakes Group 的新发现的真核微化石以及关键化学地层数据的校准点施加了重要限制。