Mazatzal-Labradorian-age (1.7-1.6 Ga) ductile deformation of the South Range Sudbury impact structure at the Thayer Lindsley mine, Ontario
Mazatzal-Labradorian-age (1.7-1.6 Ga) ductile deformation of the South Range Sudbury impact structure at the Thayer Lindsley mine, Ontario
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安大略省 Thayer Lindsley 矿南萨德伯里冲击结构的马扎特扎尔-拉布拉多时代 (1.7-1.6 Ga) 延性变形
DOI：
10.1139/e04-098
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发表时间：
2004
影响因子：
1.4
通讯作者：
D. Archibald
中科院分区：
文献类型：
--
作者：
J. Bailey;B. Lafrance;A. McDonald;J. Fedorowich;S. Kamo;D. Archibald
塞耶·林德斯利矿位于萨德伯里撞击构造的南部山脉，靠近1.85吨Ga萨德伯里火成岩杂岩(SIC)和古元古代南部省之间的接触。该矿镍铜矿带强烈变形于南东向倾斜、低角闪岩品位的剪切带内，抵消了碳化硅与南方省岩石之间的接触。许多剪切感指标，包括剪切带、拖曳褶皱和δ和σ类型的旋转斑岩碎屑，一致表明剪切带中平行于矿物伸展线理的南北向、反向、倾滑运动。该剪切带的产状、滑动方向和变质程度与萨德伯里碰撞构造后北西向韧性收缩形成的区域性北东向南岭剪切带相似。南岭剪切带通常被解释为约1.9-1.8百万年的GaPenokean构造。来自塞耶林德斯利剪切带的无面体棕色钛铁矿颗粒的207Pb206PbPenokean平均年龄为1815±15 Ma。这些颗粒被年轻的、同构造的、无色的钛铁矿包裹，其平均207Pb/206Pb年龄为1658±68 Ma。这一较年轻的年龄表明，南岭和塞耶林德斯利剪切带可能是在从美国西南部沿劳伦西亚东南边缘记录的1.7-1.6Ga碰撞构造事件期间形成的。从拉布拉多(Mazatzal Orogeny)出发，穿过中部大陆到达威斯康星州，并远至东北拉布拉多(Labradorian Orogeny)。~(40)Ar/~(39)Ar分析表明，在萨德伯里地区长英质深成作用期间，黑云母发生了1477±8 Ma的构造后热重置。
The Thayer Lindsley mine is located in the South Range of the Sudbury impact structure, near the contact between the 1.85 Ga Sudbury Igneous Complex (SIC) and the Paleoproterozoic Southern Province. Ni–Cu ore zones at the mine are strongly deformed within a southeast-dipping, lower amphibolite-grade shear zone, which offsets the contact between the SIC and Southern Province rocks. Numerous shear sense indicators, including shear bands, drag folds, and δ- and σ-type rotated porphyroclasts, consistently indicate south-over-north, reverse, dip-slip movement parallel to the mineral stretching lineation in the shear zone. The attitude, slip direction, and metamorphic grade of the shear zone are similar to those of the regional northeast-striking South Range Shear Zone that formed during post-impact, northwest-directed ductile contraction of the Sudbury impact structure. The South Range Shear Zone is generally interpreted as a ca. 1.9–1.8 Ga Penokean structure. Anhedral brown titanite grains from the Thayer Lindsley shear zone yield a mean 207Pb/206Pb Penokean age of 1815 ± 15 Ma. These grains are mantled by younger, syntectonic, colourless titanite, which have a mean 207Pb/206Pb age of 1658 ± 68 Ma. This younger age suggests that the South Range and Thayer Lindsley shear zones may have formed during a 1.7–1.6 Ga collisional tectonic event that is recorded along the southeast margin of Laurentia from the southwest USA. (Mazatzal Orogeny), through the mid-continent to Wisconsin, and as far northeast as Labrador (Labradorian Orogeny). 40Ar/39Ar analyses indicate post-tectonic thermal resetting of biotite occurred at 1477 ± 8 Ma during felsic plutonism across the Sudbury area.