The continental collision zone, South Island, New Zealand: Comparison of geodynamical models and observations
The continental collision zone, South Island, New Zealand: Comparison of geodynamical models and observations
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DOI：
10.1029/95jb02401
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发表时间：
1996-02-10
影响因子：
3.9
通讯作者：
Fullsack, P
中科院分区：
文献类型：
--
作者：
Beaumont, C;Kamp, PJJ;Fullsack, P
南岛斜向陆-陆会聚带发生在沿着现代澳大利亚-太平洋板块边界带的400 km长的部分上，自大约10 Ma以来，该部分缩短了大约50 km。造山带由中央山脉（南阿尔卑斯山脉）组成，两侧为前陆盆地。造山带的两个基本特征是：（1）伴随变形的剥蚀程度;（2）基本的构造不对称性。造山带结构的不对称性可以用平面应变、地幔俯冲的大陆会聚有限元模型来解释。模式与造山带极性的比较表明太平洋板块地幔俯冲。该模型预测两个地壳规模的倾斜剪切带，形成以上的点，太平洋地幔俯冲。距传入板块较远的局部剪切带（后阶式剪切带）对应于阿尔卑斯山断层，而其共轭剪切带（前阶式剪切带）对应于分布于山脉带东缘的应变和逆冲作用，沿着。修改模型边界条件的参数（顶面、剥蚀程度;基底带、俯冲载荷、壳幔速度不连续、下地壳俯冲、地幔后退、地幔速度分布性降低）与地壳内部强度（二层地壳，中度耦合，温度分布，应变弱化）在一系列数值模型计算中是变化的，这些数值模型计算建立了材料特性和边界条件的组合，这些边界条件导致模拟碰撞区的不同横截面结构。反过来，这些观察南岛造山带进行了比较。计算结果表明，整个造山带的变形方式和变形程度取决于地壳层的流变特性，以及地壳层的内部强度与边界应力和重力应力的综合效应之间的平衡。北到南沿走向的宽度和两维结构的造山带，在实验中模拟的模型参数的变化，可以解释的组合向南增加的预收敛地壳厚度，地热梯度，收敛，潜在的俯冲撤退，增加的可能性向南减少的组成部分，下地壳俯冲。
The South Island zone of oblique continent-continent convergence occurs along a 400 km-long section of the modern Australia-Pacific plate boundary zone, across which about 50 km of shortening has been accommodated since about 10 Ma. The orogen comprises a central mountain range (Southern Alps) flanked on both sides by what are interpreted to be foreland basins, Two essential features that characterize the orogen are (1) the degree of denudation that accompanied deformation, and (2) a fundamental structural asymmetry. The architectural asymmetry of the orogen can be explained by plane strain, finite element models of continental convergence incorporating mantle subduction. Comparison of model and orogen polarity implies that Pacific plate mantle subducts. The models predict two crustal-scale dipping shear zones that form above the point where the Pacific mantle subducts. The localized one more distant from the incoming plate (retro-step-up shear zone) corresponds to the Alpine fault, whereas its conjugate (pro-step-up shear zone) corresponds to the distributed strain and thrusting along the eastern margin of the mountain belt. Parameters that modify the model boundary conditions (top surface, degree of denudation; basal zone, subduction load, crust-mantle velocity discontinuity, subduction of lower crust, mantle retreat, and distributed decrease in mantle velocity) and the internal strength of the crust (two-layer crust with moderate coupling, temperature distribution, strain weakening) are varied in a series of numerical model calculations that establish the combination of material properties and boundary conditions that lead to different cross sectional architectures of the modeled collision zone. In turn, these are compared with observations about the South Island orogen. The calculations show how the style and extent of deformation across the whole orogen depend on the rheological properties of the crustal layer and on the balance between its internal strength and the combined effects of the boundary and gravitational stresses. North to south along-strike differences in the width and two-dimensional architecture of the orogen, simulated in the experiments by varying the model parameters, can be explained by a combination of southward increases in preconvergent crustal thickness, geothermal gradient, convergence, and potentially subduction retreat, with the added possibility of a southward decrease in the component of lower crustal subduction.