Detrital Zircon Geochronology of Basal Cambrian Strata in the Deep Illinois Basin, USA: Evidence for the Paleoproterozoic-Cambrian Tectonic and Sedimentary Evolution of Central Laurentia
Detrital Zircon Geochronology of Basal Cambrian Strata in the Deep Illinois Basin, USA: Evidence for the Paleoproterozoic-Cambrian Tectonic and Sedimentary Evolution of Central Laurentia
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DOI：
10.1086/708432
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发表时间：
2020-05-01
影响因子：
1.8
通讯作者：
Malone, Shawn J.
中科院分区：
文献类型：
--
作者：
Freiburg, Jared T.;Holland, Mark E.;Malone, Shawn J.
我们目前960碎屑锆石年龄从三个新的，深钻孔从伊利诺伊盆地，美国。这些锆石年龄谱揭示了晚古元古代通过早寒武世构造历史的伊利诺伊盆地，包括证据的时间的发展Reelfoot裂谷和Rodinia的解体的新细节。最古老的碎屑锆石人口是1650马，比任何已知的年龄结晶岩石从其他深钻芯在盆地和显着缺席的其他寒武纪地层在该地区。我们解释这个人口已来自晚古元古代地壳存在于伊利诺伊盆地和寒武纪地层的沉积过程中暴露。主要年龄峰值为1375 Ma，是南部花岗岩流纹岩省的火成岩特征，但也存在于东部花岗岩流纹岩省（EGRP）的圣弗朗索瓦山脉。1460马碎屑锆石的第二个高峰反映了已知的年龄的结晶岩石，其特征EGRP确定从沿着周边的伊利诺伊盆地。寒武纪地层中的碎屑锆石的人口可能反映了更大的丰度1370马地壳下的伊利诺伊盆地比目前公认的。这些数据表明，在伊利诺伊盆地的寒武纪砂岩基底有一个碎屑锆石的来源，这是从上覆晚寒武世砂屑岩和以前未知的北方臂Reelfoot裂谷延伸到伊利诺伊州中部，这是超过300公里，比目前绘制的北部不同。里尔富特裂谷的开口是新元古代和早寒武世期间罗迪尼亚更广泛裂谷的一部分，其标志是锆石，可能来自里尔富特裂谷火成岩，年龄范围为540至525 Ma。
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.