Abstract Metasedimentary subprovinces within the Superior Province and many Archean cratons worldwide occur as prominent belts separating volcano-plutonic subprovinces. The stages of their development mark major, distinct geodynamic events. Deposition ubiquitously follows a restricted period of voluminous, regional, felsic pluton emplacement. Their geodynamic setting of deposition is not well understood, and despite similar sedimentological, structural and post-deposition metamorphic characteristics, metasedimentary subprovinces have been variously interpreted as developing in accretionary prism, syn-orogenic, and back-arc basin settings. We present the first synthesis of detrital zircon U-Pb LA-ICP-MS geochronology from paragneiss and migmatite of the Opinaca and La Grande subprovinces. This study constrains detrital zircon age populations of the sedimentary protoliths, assesses their provenance, and evaluates the geodynamic setting of deposition. Including detrital geochronology compiled from regional literature, nine paragneiss samples from the Laguiche Complex (Opinaca) and eleven from the Riviere Salomon, Thor, Keyano, Magin, Marbot, Low and Ekomiak formations (La Grande) provide dominant modal age peaks similar to regional Neoarchean felsic plutonic suites, and lesser age peaks consistent with regional Neoarchean and Mesoarchean greenstone belts and Mesoarchean gneiss. The units have comparable zircon age populations; therefore we interpret a shared provenance from the La Grande and Minto subprovinces, suggesting that none of the metasedimentary units represent exotic accreted terranes. Mean ages of youngest LA-ICP-MS zircon age clusters range from 2716 to 2695 Ma, thus defining the maximum ages of deposition. ID-TIMS analyses of select youngest grains confirm the efficacy of the LA-ICP-MS constraints. Regional intrusive suites ranging from ca. 2710 to 2678 Ma further constrain deposition to a short time interval. Our detrital geochronology results are similar to all other Superior Province metasedimentary subprovinces, which consistently exhibit large proportions of detrital zircon ages close to their depositional age. This would conventionally lead to the interpretation that the extensional environment is a back-arc basin to an active convergent margin. However, as the sequence of events preceding formation of the Opinaca subprovince may not reflect uniformitarian tectonic processes, we discuss alternate models of basin formation and how the similar patterns observed in Superior Province detrital geochronology could be consistent with a variety of geodynamic environments.

中文翻译：

---

苏必利尔省新太古代变沉积带的地球动力学意义：Opinaca 和 La Grande 亚省碎屑锆石 U-Pb LA-ICP-MS 年代学

摘要 苏必利尔省内的变质沉积亚省和世界各地的许多太古代克拉通作为分隔火山-深成岩亚省的突出带出现。它们的发展阶段标志着主要的、独特的地球动力学事件。沉积无处不在，伴随着大量的、区域性的、长英质岩体侵位的有限时期。它们沉积的地球动力学环境尚不清楚，尽管类似的沉积学、构造和沉积后变质特征，变沉积亚省已被不同地解释为在增生棱柱、同造山和弧后盆地环境中发育。我们首次从 Opinaca 和 La Grande 亚省的副片麻岩和混合岩中合成碎屑锆石 U-Pb LA-ICP-MS 年代学。这项研究限制了沉积原岩的碎屑锆石年龄群，评估了它们的来源，并评估了沉积的地球动力学环境。包括从区域文献汇编的碎屑地质年代学，来自 Laguiche 杂岩体 (Opinaca) 的 9 个副片麻岩样品和来自 Riviere Salomon、Thor、Keyano、Magin、Marbot、Low 和 Ekomiak 地层 (La Grande) 的 11 个副片麻岩样品提供了与区域新太古代相似的主要模态年龄峰值长英质深成岩套，以及与区域新太古代和中太古代绿岩带和中太古代片麻岩一致的较小年龄峰。这些单元具有可比的锆石年龄群；因此，我们解释了来自 La Grande 和 Minto 次省的共同出处，表明没有一个变沉积单元代表外来的增生地体。最年轻的 LA-ICP-MS 锆石年龄簇的平均年龄范围为 2716 至 2695 Ma，因此定义了最大沉积年龄。选定最年轻晶粒的 ID-TIMS 分析证实了 LA-ICP-MS 约束的有效性。区域侵入式套房，范围从约。2710 至 2678 Ma 进一步将沉积限制在较短的时间间隔内。我们的碎屑年代学结果与所有其他苏必利尔省变沉积亚省相似，这些亚省始终显示出接近其沉积年龄的大比例碎屑锆石年龄。这通常会导致拉伸环境是弧后盆地到活动会聚边缘的解释。然而，由于奥皮纳卡亚省形成之前的一系列事件可能无法反映均变论的构造过程，