Reconstruction of a large deep-crustal terrane: Implications for the Snowbird tectonic zone and early growth of Laurentia
Reconstruction of a large deep-crustal terrane: Implications for the Snowbird tectonic zone and early growth of Laurentia
复制标题
大型深地壳地体的重建：对雪鸟构造带和劳伦西亚早期生长的影响
DOI：
10.1130/g21273.1
复制
发表时间：
2005
期刊：
影响因子：
5.8
通讯作者：
Michael L. Williams
中科院分区：
文献类型：
--
作者：
K. Mahan;Michael L. Williams
长约2800公里的雪鸟构造带是加拿大西部地盾的一个广为人知但仍然神秘的特征。它被解释为古元古代大陆缝合线或太古宙走滑断裂系统，但在这里，我们认为中央雪鸟构造带的独特几何形状主要是由于古元古代横切陆内逆冲带和数百公里长的走滑剪切带的相互作用。首先，与苏必利尔省和西丘吉尔省之间的早期大陆-大陆碰撞同时发生的一个主要逆冲剪切带，容纳了大量麻粒岩相下陆壳的隆起。较年轻的走滑剪切带，可能类似于喜马拉雅造山带后面的亚洲断层系统，抵消了逆冲带。因此，该地区深部岩石的几何形态和分布代表了丘吉尔省西部构造演化的一个相对较晚的阶段，而不是一个增生阶段。与雪鸟构造带成高角度的早期构造可能记录了Laurentia地区的基本增生史。
The ∼2800-km-long Snowbird tectonic zone is a well-recognized but still enigmatic feature in the western Canadian Shield. It has been interpreted as a Paleoproterozoic continental suture or an Archean strike-slip fault system, but here we suggest that the distinctive geometry of the central Snowbird tectonic zone is primarily due to the interaction of crosscutting Paleoproterozoic intracontinental thrust and strike-slip shear zones having a length of hundreds of kilometers. First, a major zone of thrust-sense shearing, coeval with early continent-continent collision between the Superior and western Churchill provinces, accommodated uplift of a large exposure of granulite facies lower continental crust. Younger strike-slip shear zones, perhaps analogous to Asian fault systems behind the Himalayan orogen, offset the thrust zone. Thus, the current geometry and distribution of deep-crustal rocks in this region represent a relatively late stage in the tectonic evolution of the western Churchill province rather than an accretionary one. Earlier structures oriented at a high angle to the Snowbird tectonic zone may record the fundamental accretionary history in this part of Laurentia.