Growth, overprinting, and stabilization of Proterozoic provinces in the southern Lake Superior region
Growth, overprinting, and stabilization of Proterozoic provinces in the southern Lake Superior region
复制标题
苏必利尔湖南部地区元古代省份的生长、叠印和稳定
DOI：
10.31223/osf.io/45ns9
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发表时间：
2019
影响因子：
3.8
通讯作者：
B. Jicha
中科院分区：
文献类型：
--
作者：
D. Holm;L. Medaris;K. McDannell;D. Schneider;K. Schulz;B. Singer;B. Jicha
摘要 苏必利尔湖南部地区的新地质年代学数据提供了有关第 18 代佩诺克造山运动期间劳伦古元古代初始生长前后构造活动的时间和性质的关键信息。逆冲彭宾蛇绿岩沿古元古代海洋盆地边缘形成，距今至少 30 年。在 1860 Ma 开始的佩诺肯岛弧/微大陆增生之前。在佩诺克造山运动之后，镁铁质岩脉在 1817 ± 2 Ma 的侵入表明了一段与 30 m.y. 相一致的延伸时期。 1835-1805 Ma（在佩诺克造山运动和亚瓦派造山运动之间）造山带长英质岩浆活动的间隙，可能代表佩诺凯亚挤压的松弛以及与亚瓦派俯冲开始相关的构造转向弧内伸展。随后的亚瓦派弧增生（1750-1720 Ma）导致岩脉和主岩在约 700 °C 的温度下普遍发生延性变形，此前归因于佩诺克阶变形。 Geon 16 Mazatzal 对增生的 Penokean 省和 Yavapai 省的叠印很普遍，但总体变质程度较低（绿片岩相），1476-1470 Ma 浅层 Wolf River 岩基的热效应仅限于侵入体周围 10-15 km 宽的接触带。与北部的太古宙苏必利尔省相反，苏必利尔湖南部地区的古元古代地体经历了大约 100 亿年的大范围低温再加热和浅层地壳冷却。 1.1–1.0 Ga 主要归因于岩浆底侵作用，随后的新元古代折返很少。在苏必利尔湖南部地区，广泛的岩浆底侵作用可能使元古代佩诺克阶-马扎扎尔岩石圈增厚、强化和稳定，但使北部太古代宙克拉通苏必利尔省岩石圈变得不稳定。
Abstract New geochronologic data in the southern Lake Superior region provide key information on the timing and nature of tectonic activity that pre-and post-date initial Paleoproterozoic growth of Laurentia during the geon 18 Penokean orogeny. The obducted Pembine ophiolite formed along the edge of a Paleoproterozoic ocean basin at least 30 m.y. prior to Penokean island arc/microcontinent accretion beginning at 1860 Ma. Following Penokean orogenesis, intrusion of mafic dikes at 1817 ± 2 Ma indicate a period of extension that coincided with a 30 m.y. gap in orogenic felsic magmatism at 1835–1805 Ma (between the Penokean and Yavapai orogenies) and likely represents relaxation of Penokean compression and a tectonic switch to intra-arc extension related to initiation of Yavapai subduction. Subsequent Yavapai arc accretion (1750–1720 Ma) resulted in pervasive ductile deformation of the dikes and host rocks at temperatures of ~700 °C, previously attributed to Penokean deformation. Geon 16 Mazatzal overprinting of the accreted Penokean and Yavapai provinces was widespread but of overall lower metamorphic grade (greenschist facies), and the thermal effects of the 1476–1470 Ma shallow level Wolf River batholith was limited to a 10–15 km wide contact zone surrounding the intrusion. In contrast to the Archean Superior Province to the north, Paleoproterozoic terranes in the southern Lake Superior area experienced widespread low-temperature reheating and cooling of shallow crustal levels at ca. 1.1–1.0 Ga attributed primarily to magmatic underplating with little subsequent Neoproterozoic exhumation. In the southern Lake Superior region widespread magmatic underplating likely thickened, strengthened, and stabilized Proterozoic Penokean-Mazatzal lithosphere but destabilized Archean cratonized Superior Province lithosphere to the north.
影响因子：
3.8
作者：
J. Craddock;D. Malone;M. Schmitz;Jennifer N. Gifford
通讯作者：
J. Craddock;D. Malone;M. Schmitz;Jennifer N. Gifford