Interaction between collisional orogenesis and convergent-margin processes: evolution of the Cambrian proto-Pacific margin of East Gondwana
Interaction between collisional orogenesis and convergent-margin processes: evolution of the Cambrian proto-Pacific margin of East Gondwana
复制标题
碰撞造山与汇聚边缘过程之间的相互作用：东冈瓦纳寒武纪原太平洋边缘的演化
DOI：
10.1144/0016-764904-087
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发表时间：
2005
影响因子：
2.7
通讯作者：
C. Wilson
中科院分区：
文献类型：
--
作者：
R. J. Squire;C. Wilson
东冈瓦那原太平洋边缘寒武纪岩浆、沉积、构造和变质事件难以对比，导致该地区被划分为澳大利亚的德拉梅尔、拉克伦和泰安南造山带，南极洲的罗斯造山带和新西兰的高卡地体。因此，人们对该地区寒武纪的构造演化知之甚少。我们给出了维多利亚西部斯塔威尔附近出露的早晚中寒武世岩石的修正岩石地层剖面，作为东冈瓦那地区地质事件对比的基础。这些资料表明，东冈瓦那4000公里长的原太平洋边缘的寒武纪构造演化以挤压造山作用为主，其间隔着约516-514 Ma和504-500 Ma的主要短暂伸展事件。最重要的伸展事件发生在约516-514 Ma，伴随着东西冈瓦那碰撞终止后全球板块运动和板块边界应力的重大变化，板块沿原太平洋边缘发生了大规模的板块退缩。浮力陆壳带的部分俯冲导致塔斯马尼亚年轻的热弧前岩石圈在510 Ma左右发生局部俯冲带破裂和俯冲。大陆带的碰撞也显着改变了原太平洋边缘的结构，最终控制了与板岩退回有关的第二次重大伸展事件的范围，大约在504-500 Ma。因此，东冈瓦那原太平洋边缘的构造演化涉及到汇聚边缘过程与碰撞造山作用之间的复杂相互作用。
Difficulties in correlating the Cambrian magmatic, depositional, structural and metamorphic events along the proto-Pacific margin of East Gondwana have led to subdivision of the region into the Delamerian, Lachlan and Tyennan Orogens in Australia, the Ross Orogen in Antarctica and the Takaka Terrane in New Zealand. As a result, the Cambrian tectonic evolution of the region is poorly understood. We present here a revised lithostratigraphic section from the late Early to Mid-Cambrian rocks exposed near Stawell in western Victoria, which is used as the basis for correlating geological events in East Gondwana. These data show that the Cambrian tectonic evolution of East Gondwana's >4000 km long proto-Pacific margin involved predominantly compressional orogenesis separated by major short-lived extensional events at c. 516–514 and 504–500 Ma. The most significant extensional event, at c. 516–514 Ma, involved extensive slab rollback along the proto-Pacific margin in response to major changes in global plate motions and plate-boundary stresses following the termination of East–West Gondwana collision. Partial subduction of a ribbon of buoyant continental crust led to localized subduction-zone failure and obduction of the young hot forearc lithosphere in Tasmania at c. 510 Ma. Collision of the continental ribbon also significantly modified the architecture of the proto-Pacific margin and ultimately controlled the extent of the second major extensional event associated with slab rollback at c. 504–500 Ma. Tectonic evolution of the proto-Pacific margin of East Gondwana thus involved the complex interaction between convergent-margin processes and collisional orogenesis.