Cryogenian intraplate magmatism along the buried southern Laurentian margin: Evidence from volcanic clasts in Ordovician strata, Marathon uplift, west Texas
Cryogenian intraplate magmatism along the buried southern Laurentian margin: Evidence from volcanic clasts in Ordovician strata, Marathon uplift, west Texas
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沿埋藏的劳伦南部边缘的低温期板内岩浆作用：来自德克萨斯州西部马拉松隆起奥陶纪地层火山碎屑的证据
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发表时间：
2016
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影响因子：
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通讯作者：
C. Fanning
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作者：
R. Hanson;J. Roberts;P. Dickerson;C. Fanning
关于元古代末期罗迪尼亚超大陆分裂历史的关键证据来自于罗迪尼亚碎裂期间释放的克拉通块体边缘分布的广泛的成冰期-寒武纪板内火成岩组合，这些岩浆组合现在分布在全球各地。这种岩浆作用在罗迪尼亚分裂之前和最后阶段发生在劳伦西亚克拉通东部、西部和北部边缘的很长一段时间内（780-540 Ma），劳伦克拉通在许多重建中构成了罗迪尼亚的中心。由于深埋在较年轻的地层之下，类似的长期岩浆活动是否发生在劳伦南部边缘的裂谷-漂移转变之前仍然不确定。我们提供了源自陆架的奥陶纪浊积岩和泥石流沉积物中火山碎屑的地球化学和年代学数据，这些沉积物现在暴露在美国德克萨斯州西部马拉松隆起的异地逆冲切片中，这些数据记录了沿着古代边缘的这一部分至少追溯到 706 Ma 的一次或多次板内岩浆活动。这些数据提出了一种可能性，即在罗迪尼亚分裂之前，劳伦大陆可能已被板内火成岩活动完全包围，这对导致超大陆破碎的驱动力以及控制该过程中洋盆形成地点的因素具有影响。
Critical evidence bearing on the breakup history of the supercontinent Rodinia near the end of the Proterozoic comes from widespread Cryogenian–Cambrian intraplate igneous assemblages present along the margins of cratonic blocks released during Rodinia fragmentation and now distributed around the globe. This magmatism occurred over a long time span (780–540 Ma) prior to and during final stages of Rodinia breakup along the eastern, western, and northern margins of the Laurentia craton, which forms the centerpiece of Rodinia in many reconstructions. Whether similar protracted magmatism occurred prior to the rift-drift transition along the southern Laurentian margin has remained uncertain because of deep burial beneath younger strata. We present geochemical and geochronological data from volcanic clasts within shelf-derived Ordovician turbidites and debris-flow deposits now exposed in allochthonous thrust slices in the Marathon uplift, west Texas (USA), that document one or more episodes of intraplate magmatism extending back at least to 706 Ma along this part of the ancient margin. These data raise the possibility that Laurentia may have been completely encircled by intraplate igneous activity prior to Rodinia breakup, with implications for the driving forces leading to supercontinent fragmentation and factors controlling the sites of ocean-basin formation during that process.