Abstract

The Adelaide Rift Complex in South Australia records the break-up of Rodinia at a time of great climatic and biological evolution. The Boucaut Volcanics within the Neoproterozoic Adelaide Rift Complex of the Adelaide Superbasin lie at the base of the Burra Group, marking the boundary between the Burra Group and underlying Callanna Group. Despite their significance as one of the few volcanic units within the rift complex, there has been no robust age determination published for the Boucaut Volcanics. We use U–Pb zircon LA-ICP-MS data to determine an age of 788 ± 6 Ma for the eruption of the bimodal Boucaut Volcanics. This has important implications for constraining the timing of stratigraphy within the Adelaide Superbasin. This also has far-reaching implications for plate tectonic reconstructions of Australia and Laurentia, and for correlating global isotope anomalies for the Neoproterozoic.

1. KEY POINTS

2. New U–Pb zircon data provide a revised age for the Boucaut Volcanics of 788 ± 6 Ma.

3. Whole-rock geochemistry data highlight the bimodality of the Boucaut Volcanics, with both mafic and felsic components present.

4. Boucaut Volcanics potentially correlate with units in the southwest United States, which would support an AUSWUS plate tectonic configuration during the Neoproterozoic.

摘要

南澳大利亚州的阿德莱德裂谷综合体记录了在气候和生物发生巨大变化的时候罗迪尼亚的破裂。阿德莱德超级盆地的新元古代阿德莱德裂谷复合体中的布考特火山位于Burra组的底部，标志着Burra组与下层的Callanna组之间的边界。尽管它们是裂谷综合体中为数不多的火山单元之一的重要性，但尚无关于Boucaut火山的年龄确定的资料。我们使用U–Pb锆石LA-ICP-MS数据确定双峰Boucaut火山喷发的年龄为788±6 Ma。这对于限制阿德莱德超级盆地内地层的时间安排具有重要意义。这对澳大利亚和劳伦西亚的板块构造重建也具有深远的意义，

1. 关键点

2. 新的U–Pb锆石数据提供了Boucaut火山的年龄修订为788±6 Ma。

3. 全岩石地球化学数据突显了布考特火山的双峰性，同时存在镁铁质和长英质成分。

4. Boucaut火山岩可能与美国西南部的单元相关，这将在新元古代期间支持AUSWUS板块的构造构造。