Zircon (U‐Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera
Zircon (U‐Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera
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加拿大麦肯齐山脉新元古代地层的锆石 (U-Th)/He 热年代学：对加拿大北部科迪勒拉显生宙折返和变形历史的启示
DOI：
10.1002/2015tc003989
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发表时间：
2016
期刊：
影响因子：
4.2
通讯作者：
K. Fallas
中科院分区：
文献类型：
--
作者：
J. Powell;D. Schneider;D. Stockli;K. Fallas
新元古代麦肯齐山脉超群（MMSG）和温德米尔超群（WSG）的沉积地层位于加拿大科迪勒拉前陆带麦肯齐山脉背斜的核部。地层和构造证据表明，这些岩石经历了几次相对完整的埋藏和剥蚀过程。我们报道了来自褶皱冲断带和新元古代地层记录一系列样品的单颗粒碎屑白云母\(^{40}Ar/^{39}Ar\)和锆石（U - Th）/He（ZHe）数据。这些地层没有达到足以重置白云母\(^{40}Ar/^{39}Ar\)体系的高温，相反，我们的碎屑白云母数据细化了托宁期 - 成冰期的沉积年龄。单晶体ZHe年龄范围从\(432±35\)到\(46±4\)Ma，表明MMSG和WSG地层没有被加热到足以完全重置ZHe体系。这些因素使新元古代地层成为一个有吸引力的天然实验室，用于测试锆石辐射损伤和退火模型在量化来自在漫长地质时间尺度上积累了辐射损伤的碎屑锆石群体的热历史方面的实用性。热模拟显示：（1）在泥盆纪之后沉积了大量的沉积层，并在二叠纪 - 三叠纪冷却期间被移除；（2）科迪勒拉变形前缘从阿尔布期到古新世在研究区域内传播，西南部在\(75 - 67\)Ma之间以及变形前缘在\(60 - 55\)Ma之间冷却速率有适度增加。最终，锆石中辐射损伤和氦扩散动力学之间的关系解释了大量的ZHe年龄分散，并阐明了加拿大北部科迪勒拉的温度 - 时间历史。
Sedimentary strata of the Neoproterozoic Mackenzie Mountains Supergroup (MMSG) and Windermere Supergroup (WSG) occupy the cores of anticlines in the Mackenzie Mountains of the Canadian Cordilleran Foreland Belt. Stratigraphic and structural evidence suggest that these rocks have undergone several episodes of burial and unroofing relatively intact. We report single‐grain detrital muscovite 40Ar/39Ar and zircon (U‐Th)/He (ZHe) data from a suite of samples across the fold‐thrust belt and the Neoproterozoic stratigraphic record. The strata have not reached high enough temperatures to reset the muscovite 40Ar/39Ar system, and instead our detrital muscovite data refine Tonian‐Cryogenian depositional ages. Single‐crystal ZHe dates range from 432 ± 35 to 46 ± 4 Ma, indicating that MMSG and WSG strata have not been heated sufficiently to fully reset the ZHe system. These factors make the Neoproterozoic strata an attractive natural laboratory to test the utility of the zircon radiation damage and annealing model on the quantification of thermal histories from detrital zircon populations that have accumulated radiation damage over long geologic timescales. Thermal modeling reveals that (1) a substantial sedimentary package was deposited following the Devonian and removed during Permo‐Triassic cooling, and (2) the Cordilleran deformation front propagated through the study area from the Albian to the Paleocene, with a moderate increase in cooling rates between 75–67 Ma in the southwest and 60–55 Ma at the deformation front. Ultimately, relationships between radiation damage and helium diffusion kinetics in zircon explain substantial ZHe date dispersion and elucidate the temperature‐time history of the northern Canadian Cordillera.