Key-ring structure gradients and sheath folds in the Goantagab Domain of NW Namibia
Key-ring structure gradients and sheath folds in the Goantagab Domain of NW Namibia
复制标题
纳米比亚西北部Goantagab域的钥匙环结构梯度和鞘褶皱
DOI：
10.1016/j.jsg.2010.12.005
复制
发表时间：
2011
影响因子：
3.1
通讯作者：
R. Schmitt
中科院分区：
文献类型：
--
作者：
C. Passchier;R. Trouw;S. Coelho;E. Kemp;R. Schmitt
变形阶段的概念是构造地质学的基石之一，但尽管其简单，但在某些情况下该概念会失效。在纳米比亚西北部的Goantagab地区，复杂变形区域的结构可以细分为至少四组，根据套印关系归因于四个变形阶段。然而，其中三组结构是在同一构造事件期间在相似的变质环境下形成的，但流动条件略有不同。这些结构组显示出空间中的渐变过渡，可以通过“钥匙环结构渐变”的概念来理解，其中旧的 DA 结构被具有相似方向的新结构 DA+1 重新定向和叠印，并且似乎分级为套印区域之外的 DA 结构。这种行为在非均匀非同轴流中可能很常见。在 Goantagab 域的核心中，D2 结构因此被重新定向并被局部 D2b 折叠和叶状结构叠印，这些 D2b 折叠和叶状结构与域核心之外的 D2 结构具有相同的方向和样式。
The concept of deformation phases is one of the corner stones of structural geology but, despite its simplicity, there are situations where the concept breaks down. In the Goantagab Domain of NW Namibia, structures in an area of complex deformation can be subdivided into at least four sets, attributed to four deformation phases on the basis of overprinting relations. Three of these sets of structures, however, formed during the same tectonic event under similar metamorphic circumstances but slightly different flow conditions. These sets of structures show gradational transitions in space that can be understood by a concept of “key-ring structure gradients”, where older DAstructures are reoriented and overprinted by new structures DA+1that have similar orientation, and seem to grade into DAstructures outside the overprinted area. This kind of behaviour may be common in inhomogeneous non-coaxial flow. In the core of the Goantagab Domain, D2structures are thus reoriented and overprinted by local D2bfolds and foliations that have the same orientation and style as D2structures outside the domain core.