The Najd Fault System, Saudi Arabia and Egypt: A Late Precambrian rift‐related transform system?
The Najd Fault System, Saudi Arabia and Egypt: A Late Precambrian rift‐related transform system?
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内志断层系统、沙特阿拉伯和埃及：晚前寒武纪裂谷相关的转换系统？
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发表时间：
1985
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通讯作者：
R. Stern
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作者：
R. Stern
Najd断层系统是一组复杂的左旋走滑断层和韧性剪切带，走向西北-东南，横跨阿拉伯和埃及的前寒武纪。该系统形成于540-620 Ma。它的宽度可达400公里，暴露长度为1100公里;推断的Najd的埋藏延伸使其总长度为2000公里。这是最好的暴露，可能是地球上最大的前中生代横断层带。以前的模型认为，纳杰德断层系统是由一次主要的晚前寒武纪大陆-大陆碰撞形成的。这一模式在这里并不可取，因为（1）缺乏证据表明纳杰德断裂系统以东存在一个前晚前寒武纪大陆;（2）纳杰德断裂系统的方向与滑移线理论预测的方向存在差异;（3）纳杰德运动的年龄比阿拉伯地盾碰撞缝合线的年龄小;（4）缺乏伴随碰撞而产生的大范围地壳隆起的证据。一个新的模型解释了纳杰断层系统的起源：纳杰断层系统的形成是对一个广泛的西北-东南方向地壳伸展的响应，伴随着最北端的非洲-阿拉伯半岛的幼年大陆地壳形成。这个模型还解释了以下观察结果：（1）Najd的分支平行于埃及和西奈半岛东北沙漠的延伸方向;（2）主要裂谷运动的时间（约1000年）。575-600 Ma）与Najd（ca.（3）尽管观察（2），Najd断层系统在最北部的非洲-阿拉伯半岛没有被识别出来;相反，Najd变形变得越来越具有韧性，随着主伸展带的接近，这些带更常见地被剪切和片理化花岗岩侵入。因此，Najd断层系统代表了一组大陆转换，在响应一个主要的情节，在最北端的非洲-阿拉伯半岛晚前寒武纪伸展大陆地壳形成。
The Najd Fault System is a complex set of left-lateral strike-slip faults and ductile shear zones that strike NW-SE across the Precambrian of Arabia and Egypt. This system was developed during the interval 540–620 Ma. It is up to 400 km wide with an exposed length of 1100 km; inferred buried extensions of the Najd give it a total length of 2000 km. It is the best exposed and may be the largest pre-Mesozoic zone of transcurrent faulting on earth. Previous models for the Najd Fault System suggest it formed as a result of a major Late Precambrian continent-continent collision. This model is not preferred here because (1) the lack of evidence for a pre-Late Precambrian continent to the east of the Najd Fault System; (2) the difference between the orientation of the Najd Fault System and that predicted by slip-line theory; (3) the younger age of Najd movements compared with that of collisional sutures in the Arabian Shield; and (4) lack of evidence for wide-spread crustal uplift that would be expected to accompany collision. A new model for the origin of the Najd Fault System accounts for each of these objections: The Najd Fault System formed in response to a broad zone of NW-SE directed crustal extension that accompanied juvenile continental crustal formation in northernmost Afro-Arabia. This model also accounts for the following observations: (1) Strands of the Najd parallel the direction of extension in the North Eastern Desert of Egypt and Sinai; (2) the timing of the principal rifting movements (ca. 575–600 Ma) overlap with those of the Najd (ca. 560–620 Ma); (3) in spite of observation (2), the Najd Fault System is not recognized in northernmost Afro-Arabia; instead the Najd deformation becomes increasingly ductile and these zones are more commonly intruded by sheared and foliated granites as the principal zone of extension is approached. The Najd Fault System thus represents a set of continental transforms developed in response to a major episode of Late Precambrian extensional continental crust formation in northernmost Afro-Arabia.