We present 960 detrital zircon ages from three new, deep boreholes from the Illinois Basin, USA. These zircon age spectra reveal new details of the late Paleoproterozoic through early Cambrian tectonic history of the Illinois Basin, including evidence of the timing of the development of the Reelfoot Rift and breakup of Rodinia. The oldest detrital zircon population is ~1650 Ma, older than any known age for crystalline rocks from other deep drill cores in the basin and conspicuously absent in other Cambrian strata in the region. We interpret this population to have been derived from late Paleoproterozoic crust that exists beneath the Illinois Basin and was exposed during the deposition of Cambrian strata. The principal age peak is ~1375 Ma, characteristic of igneous rocks of the Southern Granite-Rhyolite Province but also present in the St. Francois Mountains of the Eastern Granite-Rhyolite Province (EGRP). A secondary peak of ~1460 Ma detrital zircon reflects the known ages of crystalline rocks that characterize EGRP determined from along the periphery of the Illinois Basin. This population of detrital zircon in Cambrian strata may reflect a greater abundance of ~1370 Ma crust beneath the Illinois Basin than presently recognized. These data reveal that basal Cambrian sandstones in the Illinois Basin have a detrital zircon provenance that is distinct from the overlying late Cambrian arenites and that a previously unknown northern arm of the Reelfoot Rift extends into central Illinois, which is more than 300 km further north than currently mapped. The opening of the Reelfoot Rift, which was part of the broader rifting of Rodinia during the Neoproterozoic and early Cambrian, is marked by zircons, probably from Reelfoot Rift igneous rocks, that range from 540 to 525 Ma.

中文翻译：

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美国伊利诺伊州深盆地基底寒武纪地层碎屑锆石年代学：古元古代-寒武纪构造和中劳伦大陆沉积演化的证据

我们展示了来自美国伊利诺伊州盆地的三个新的深钻孔的 960 个碎屑锆石年龄。这些锆石年龄谱揭示了伊利诺伊盆地早期寒武纪构造历史中晚古元古代的新细节，包括 Reelfoot 裂谷发育时间和 Rodinia 解体的证据。最古老的碎屑锆石群大约为 1650 Ma，比该盆地其他深钻岩芯中结晶岩的任何已知年龄都要古老，并且在该地区的其他寒武系地层中明显不存在。我们将这个种群解释为来自伊利诺伊州盆地下方的晚古元古代地壳，并在寒武纪地层沉积期间暴露出来。主要年龄峰值为~1375 Ma，是南部花岗岩-流纹岩省火成岩的特征，但也存在于圣彼得堡。东部花岗岩流纹岩省 (EGRP) 的弗朗索瓦山脉。约 1460 Ma 碎屑锆石的次要峰反映了结晶岩的已知年龄，这些结晶岩的特征是从伊利诺伊州盆地的外围确定的 EGRP。寒武纪地层中的这些碎屑锆石群可能反映了伊利诺伊盆地下方约 1370 Ma 地壳的丰度比目前认识的要高。这些数据表明，伊利诺伊州盆地的基底寒武纪砂岩具有不同于上覆晚寒武纪砂岩的碎屑锆石物源，并且之前未知的 Reelfoot Rift 北臂延伸到伊利诺伊州中部，距伊利诺伊州北部 300 多公里。当前映射。Reelfoot 裂谷的开放，它是新元古代和寒武纪早期罗迪尼亚大裂谷的一部分，