Cenozoic transtension along the Transantarctic Mountains‐West Antarctic rift boundary, southern Victoria Land, Antarctica
Cenozoic transtension along the Transantarctic Mountains‐West Antarctic rift boundary, southern Victoria Land, Antarctica
复制标题
沿横贯南极山脉-南极洲西部裂谷边界的新生代张拉，南极洲维多利亚地南部
作者：
T. Wilson
沿着横贯南极山脉和西南极裂谷系之间的构造边界绘制的脆性断层阵列与山脉和近海裂谷盆地的轴线倾斜。因此，北-西北走向的区域裂谷边界不受连续裂谷边界断层的控制。相反，裂谷边缘的趋势必须强加的继承岩石圈弱点沿着祖先东南极克拉通边缘。断层运动学的解决方案表明，右旋扭张制度的特点在新生代的裂谷边界，并占主导地位的横向运动发生在最近的断层幕。跨南极山脉被认为是一个裂谷翼隆起，但没有实质性的均衡隆升预计在一个transstensional设置，和机制的大幅度新生代隆升的山脉仍然存在问题。区域变形模式在维多利亚土地和罗斯海可以解释一个transtensional模型，并不兼容的大规模地壳拉伸在新生代的西南极裂谷系统。裂谷系统的地壳变薄更可能发生在中生代，当时主要的西南极地壳块体运动发生。新生代陆内变形可能与全球始新世板块重组导致的板块相互作用有关，在南极洲和澳大利亚东南部边缘的一个狭窄凸起最终分离之前。位移幅度可能很小，因此，第三纪早期的东西南极运动不太可能解释全球板块运动回路的差异。
Brittle fault arrays mapped along the structural boundary between the Transantarctic Mountains and the West Antarctic rift system are oriented obliquely to the axis of the mountains and offshore rift basins. The north to northwest trending regional rift boundary is thus not controlled by continuous rift border faults. Instead, the rift margin trend must be imposed by inherited lithospheric weaknesses along the ancestral East Antarctic craton margin. Fault kinematic solutions indicate that a dextral transtensional regime characterized the rift boundary in the Cenozoic and that dominantly transcurrent motion occurred during the most recent faulting episode. The Transantarctic Mountains are considered to be a rift-flank uplift, yet no substantial isostatic uplift is expected in a transtensional setting, and the mechanism of large-magnitude Cenozoic uplift of the mountains remains problematical. Regional deformation patterns in Victoria Land and the Ross Sea can be explained by a transtensional model and are not compatible with large-magnitude crustal stretching within the West Antarctic rift system in the Cenozoic. The crustal thinning across the rift system more likely took place in the Mesozoic, when major West Antarctic crustal block motions occurred. The Cenozoic intracontinental deformation can be related to plate interaction resulting from the global Eocene plate reorganization, prior to the final separation between Antarctica and a narrow salient of the southeastern Australian margin. Displacement magnitude was probably minor, and thus early Tertiary east–west Antarctic motion is unlikely to account for discrepancies in global plate motion circuits.