Late Proterozoic to Early Palaeozoic tectonism in Dronning Maud Land, Antarctica: supercontinental fragmentation and amalgamation
Late Proterozoic to Early Palaeozoic tectonism in Dronning Maud Land, Antarctica: supercontinental fragmentation and amalgamation
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南极洲德隆宁莫德地晚元古代至早古生代构造活动：超大陆碎裂与合并
DOI：
10.1144/gsjgs.150.5.0833
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发表时间：
1993
影响因子：
2.7
通讯作者：
P. Groenewald
中科院分区：
文献类型：
--
作者：
A. Moyes;J. M. Barton;P. Groenewald
根据最近提出的中元古代期间劳伦大陆和冈瓦纳大陆之间地质连续性的建议（SWEAT假说），对德隆宁莫德地西部的中元古代-早古生代构造发育进行了研究。随着劳伦大陆从这片超大陆分裂和裂谷，冈瓦纳大陆与其余成分合并，最终在大约 10 世纪的晚寒武世造山运动中达到顶峰。 500马。德隆宁莫德地西部的中元古代-早古生代构造发育与横贯南极山脉观测到的显着不同，并且c。 500 Ma事件的具体特征是：（1）c.的区域性同位素重置事件。 470 Ma，（2）稀有的同时代岩浆作用，仅包括一次主要的碱性亲和力侵入，以及源自片麻岩局部深熔的体积较小的“S型”花岗岩片，（3）结构变形比之前的基巴兰（1100 Ma）造山运动期间明显弱化，包括相对开放的温和褶皱，（4）在基巴兰造山运动期间启动的逆冲作用重新激活，并伴有相关的交代作用。结论是，晚寒武世（约 500 Ma）事件的影响与大规模底侵导致的地壳增厚一致，而不是像横贯南极山脉的罗斯造山运动中所见的俯冲相关过程。还得出的结论是，冈瓦纳古陆合并发生在目前未暴露在 Dronning Maud 地露头的缝合线上。这些数据既不矛盾也不支持目前争论的 SWEAT 假说。
The Mid-Proterozoic-Early Palaeozoic tectonic development of western Dronning Maud Land is examined in the light of recent proposals that suggest geological continuity between Laurentia and Gondwana during the Middle Proterozoic (the SWEAT hypothesis). Gondwana amalgamation from the remaining constituents followed fragmentation and rifting of Laurentia from this supercontinent, culminating in a Late Cambrian orogeny at c. 500 Ma. The Mid-Proterozoic-Early Palaeozoic tectonic development of western Dronning Maud Land was significantly different to that observed in the Transantarctic Mountains, and the c. 500 Ma event in particular is characterized by: (1) a regional isotopic resetting event at c. 470 Ma, (2) scarce coeval magmatism, comprising only one major intrusion of alkaline affinity, and volumetrically small ‘S-type’ granitic sheets derived from local anatexis of gneisses, (3) structural deformation considerably less intense than during the preceding Kibaran (1100 Ma) orogeny, comprising relatively open to gentle folding, (4) reactivation of thrusting initiated during the Kibaran orogeny, with associated metasomatism. It is concluded that the effects of the Late Cambrian (c. 500 Ma) event are consistent with crustal thickening through large-scale underplating, rather than subduction-related processes as seen in the Ross orogeny of the Transantarctic Mountains. It is also concluded that Gondwana amalgamation occurred along suture lines not currently exposed in outcrop in Dronning Maud Land. These data neither contradict nor support the SWEAT hypothesis as currently argued.