Anatomy, structural evolution, and slip rate of a plate-boundary thrust: The Alpine fault at Gaunt Creek, Westland, New Zealand
Anatomy, structural evolution, and slip rate of a plate-boundary thrust: The Alpine fault at Gaunt Creek, Westland, New Zealand
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板块边界逆冲的解剖学、结构演化和滑动率：新西兰韦斯特兰冈特溪的高山断层
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
R. Norris
中科院分区：
文献类型：
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作者：
A. Cooper;R. Norris
新西兰韦斯特兰Gaunt Creek阿尔卑斯断层底部碎裂岩的板块矢量平行滑边趋势计算出的最小滑动率为18至24毫米/年。太平洋板块和澳大利亚板块之间总相对运动的一半到三分之二被阿尔卑斯断层这一单一构造的运动所容纳。在过去的14ka中，阿尔卑斯断层的前缘由一个中等东南倾的斜逆断层转变为一个浅倾逆冲断层。上盘（太平洋板块）由基底泥、含伪铜绿碎裂岩、逐渐序贯的片岩衍生糜棱岩组成，并与下盘（澳大利亚板块）的次水平层状、河流-冰川砾石发生断裂。在隆升过程中，上盘层序发生内部剪切和瓦叠，形成复式构造，并受普遍存在的热液流动的影响，发生脉状回退蚀变。对发掘出的断裂带的侵蚀产生了角状碎裂岩和糜棱岩衍生的角砾岩，在断裂带下形成了一个向西倾斜的围裙。距talus角砾岩基部附近的木屑的14c测年为12650±90年bp。渐进式构造缩短导致片岩推覆体在由自身侵蚀碎屑组成的不规则距talus扇表面上逆冲180米。冈特溪阿尔卑斯断层的构造历史说明了断层诱发地形和侵蚀之间相互作用的重要性，以及这些作用对断裂带持续的构造、几何和地貌演化的控制。
Minimum slip rates calculated for plate-vector-parallel slickenside trends in cataclasite on the sole of the Alpine fault at Gaunt Creek, Westland, New Zealand, range from 18 to 24 mm/yr. Between half and two-thirds of the total relative motion between the Pacific and Australian plates is being accommodated by movement on a single structure, the Alpine fault. During the past 14 ka, the leading edge of the Alpine fault has changed from a moderately southeast-dipping, oblique reverse fault to a shallowly dipping thrust. The hanging wall (Pacific plate) is composed of a gradational sequence from basal gouge, through pseudotachylite-bearing cataclasite, to progressively more coherent schist-derived mylonite, which has been faulted against subhorizontally bedded, fluvio-glacial gravel in the footwall (Australian plate). During uplift the hanging-wall sequence has been internally sheared and imbricated, producing duplex structures, and retrogressively veined and altered by pervasive hydrothermal fluid flow. Erosion of the exhumed fault zone produced angular, cataclasite- and mylonite- derived, talus-fan breccias, building a west-dipping apron beneath the fault scarp. Wood fragments from near the base off the talus breccias have been 14 C dated at 12,650 ± 90 yr B.P. Progressive tectonic shortening resulted in 180 m of overthrusting of a schist-derived nappe across an irregular talus fan surface composed of its own erosional debris. The structural history of the Alpine fault at Gaunt Creek illustrates the importance of the interaction between fault-induced topography and erosion, and the control these processes exert on the continued tectonic, geometric, and geomorphic evolution of the fault zone.