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Continental magmatic arc rotation during the assembly of western Gondwana
Journal of South American Earth Sciences ( IF 1.8 ) Pub Date : 2022-09-20 , DOI: 10.1016/j.jsames.2022.104032
Rita K. Kraus , Robert de Lima Muniz , Ticiano José Saraiva dos Santos

The Ceará Central Domain (CCD) is part of the Borborema Province and is delimited by two major NE-SW-trending strike-slip zones associated with the Transbrasiliano and Senador Pompeu lineaments. These two strike-slip zones formed in Neoproterozoic/Early Cambrian times under ductile conditions and underwent several brittle-ductile and brittle reactivation events from 540 Ma onwards, which affected Precambrian and Phanerozoic rocks, respectively, causing ductile and brittle-ductile and brittle deformation. The Transbrasiliano Lineament is an NNE-SSW-trending, 4000 km-long structure marked by strong magnetic anomalies. It is interpreted to represent a mega-suture active during the Gondwana amalgamation and/or the post-collisional shearing. The Santa Quitéria Continental Magmatic Arc, located between both lineaments, consists of a Neoproterozoic (830-620 Ma) gneissic-migmatitic association affected by collisional metamorphism (640-615 Ma). This arc has been dissected, dislocated, and rotated under brittle-ductile and brittle conditions by a set of secondary strike-slip faults, possibly interconnected with the two major Transbrasiliano and Senador Pompeu lineaments, and most likely have been contemporarily active throughout history. The roughly NNW-SSE-trending Tauá Fault, located southwest of CCD, appears to relate to both fault systems. A closer inspection of gamma-ray spectrometric data suggests a complex network of interconnecting E-W-trending brittle transcurrent faults, some of which show dextral and/or sinistral kinematics, displacing the Santa Quitéria Continental Magmatic Arc and Canindé-Independência units. We suggest a paleo-dextral ductile deformation of the Santa Quitéria Continental Magmatic Arc resulting from the coeval transcurrent activity along Transbrasiliano and Senador Pompeu lineaments. These strike-slip mega-shear zones developed an intricate pattern of the minor (first-, second-, and third stages) interconnecting strike-slip faults, along which the Santa Quitéria Continental Magmatic Arc has been displaced and rotated, under conditions that changed from ductile to brittle-ductile to brittle through time.



中文翻译:

冈瓦纳西部组装过程中的大陆岩浆弧旋转

Ceará 中央域 (CCD) 是 Borborema 省的一部分,由与 Transbrasiliano 和 Senador Pompeu 线相关的两个主要的 NE-SW 走向的走滑带划定。这两个走滑带形成于新元古代/早寒武世的韧性条件下,540 Ma以后经历了多次脆韧和脆性活化事件,分别影响了前寒武纪和显生宙岩石,造成了韧性和脆韧性和脆性变形。Transbrasiliano Lineament 是一个 NNE-SSW 走向的结构,长 4000 公里,以强磁异常为标志. 它被解释为代表在冈瓦纳合并和/或碰撞后剪切期间活跃的巨型缝合线。Santa Quitéria 大陆岩浆弧位于两条线之间,由受碰撞变质作用影响的新元古代 (830-620 Ma) 片麻岩-混合岩组合组成(640-615 毫安)。这条弧线在脆韧性和脆性条件下被一组次生走滑断层剖开、错位和旋转,可能与两个主要的 Transbrasiliano 和 Senador Pompeu 线系相互连接,并且很可能在整个历史上一直活跃。位于 CCD 西南部的大致 NNW-SSE 趋势的 Tauá 断层似乎与这两个断层系统有关。对伽马射线光谱数据的更仔细检查表明,相互连接的 EW 趋势脆性横贯断层的复杂网络,其中一些显示出右旋和/或左旋运动学,取代了 Santa Quitéria 大陆岩浆弧和 Canindé-Independência 单元。我们建议圣基特里亚大陆岩浆弧的古右旋塑性变形是由沿 Transbrasiliano 和 Senador Pompeu 线条的同时期横贯活动引起的。这些走滑大剪切带形成了一种错综复杂的小(第一阶段、第二阶段和第三阶段)相互连接的走滑断层,Santa Quitéria 大陆岩浆弧在发生变化的条件下沿着这些断层移动和旋转随着时间的推移,从韧性到脆性-韧性到脆性。

更新日期:2022-09-20
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