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首页> 外文期刊>Canadian journal of earth sciences >Geology of the Matthew Creek metamorphic zone, southeast British Columbia: a window into Middle Proterozoic metamorphism in the Purcell Basin
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Geology of the Matthew Creek metamorphic zone, southeast British Columbia: a window into Middle Proterozoic metamorphism in the Purcell Basin

机译：不列颠哥伦比亚省东南部马修克里克变质带的地质：珀塞尔盆地中元古代中期变质的窗口

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Southwest of Kimberley, southeastern British Columbia, the Matthew Creek metamorphic zone occupies the core of a structural dome in Mesoproterozoic rocks of the Lower Aldridge formation (lower Purcell Supergroup). It comprises (1) a core zone of ductilely deformed sillimanite-grade metapelites, thin foliated mafic sills, and sheared quartz-plagioclase-tourmaline- pegmatites; and (2) a thin transition zone of ductilely deformed metasediments which marks a textural and metamorphic transition between the core zone and overlying regionally extensive, brittlely deformed, biotite-grade semipelitic Lower Aldridge formation metasediments and thick Moyie sills. The core zone and transition zone in combination cover an area of 30 km~2. The deepest exposed rocks in the core zone have a strong foliation and lineation (D_1 deformation) formed during late M1 metamorphism at conditions of 580-650deg C and 3.5 +- 0.5 kbar. The timing of this metamorphic-structural episode is constrained to the interval l352-1341 Ma based on near-concordant U-Pb ages from monazite in pelitic schist near the mouth of Matthew Creek. Later, weaker metamorphic and deformation episodes variably overprinted the rocks of the Matthew Creek metamorphic zone. The juxtaposition of low-grade, weakly deformed rocks above high-grade, strongly deformed rocks across a zone of ductile deformation is interpreted to be due to a subhorizontal shear zone.
机译：马修克里克变质带位于不列颠哥伦比亚省东南部金伯利西南部，位于下阿尔德里奇地层（下珀塞尔超群）的中生代岩石中一个结构穹顶的核心。它包括（1）韧性变形的硅线石级变质岩，薄叶状镁铁基岩和剪切石英斜长石-电气石-伟晶岩的核心区; （2）韧性变形形变沉积物的薄过渡带，标志着核心区域与上覆的区域广泛的，脆性变形的，黑云母级的半石质下阿尔德里奇形成形变沉积物和厚的莫伊基岩之间的构造和变质转变。核心区和过渡区合起来占地30 km〜2。在580-650℃和3.5±0.5kbar的条件下，在M1晚期变质过程中，岩心区域中最深的裸露岩石具有很强的叶面和纹路（D_1变形）。基于来自马修溪河口附近的胶泥岩片中独居石的近乎一致的U-Pb年龄，这种变质构造事件的发生时间被限制在1352-1341 Ma区间。后来，较弱的变质作用和形变事件以不同的方式覆盖了马修溪变质带的岩石。低品位，弱变形岩石在韧性变形区域上方并置的高品位，强烈变形岩石并置，被认为是由于水平下剪切带所致。

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