Strain softening induced ductile flow in the Särv thrust sheet, Scandinavian Caledonides
Strain softening induced ductile flow in the Särv thrust sheet, Scandinavian Caledonides
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斯堪的纳维亚喀里多尼德省 Särv 推力片中的应变软化诱导延性流动
DOI：
10.1016/0191-8141(86)90062-3
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发表时间：
1986
影响因子：
3.1
通讯作者：
R. Kumpulainen
中科院分区：
文献类型：
--
作者：
J. Gilotti;R. Kumpulainen
斯堪的纳维亚喀里多尼亚山脉外部区域的特点是由来自波罗的海大陆的沉积岩组成的冲断层。 Särv 逆冲片在其中是独一无二的，因为 4.5-6 公里厚、平坦的 Tossåsfjället 群碎屑在逆冲之前被亚垂直的拉斑斑岩岩墙群侵入。 Särv 推力板是一匹大型马（长 100 公里，宽 80 公里），具有经典的斜坡平坦几何形状。岩墙的原始侵入关系在大部分冲断层中得以保留，变形集中在数十米厚的糜棱岩带的底部。在该区域，米厚的岩脉旋转至与底冲力平行，两种岩性的一致糜棱岩以厘米至毫米的尺度嵌插。 Särv 冲断片的整体刚性块体几何形状，以及由岩墙群旋转记录的强烈应变梯度和冲断带糜棱岩的同时发育，表明冲断就位是通过延性屈服和持续的假塑性流发生的。持续应变软化通过晶粒尺寸减小、反应增强延展性和晶界滑动（从微观结构推断出的过程）在该区域实现局部延性流动。
The external zone of the Scandinavian Caledonides is characterized by thrust sheets composed of sedimentary rocks derived from the continent Baltica. The Särv thrust sheet is unique amongst them because the 4.5–6 km thick, flat-lying Tossåsfjället Group clastics were intruded by a sub-vertical tholeiitic dike swarm prior to thrusting. The Särv thrust sheet is a large horse (100 km long and 80 km wide) with a classical ramp-flat geometry. The original intrusive relationships of the dikes are preserved throughout most of the thrust sheet and deformation is concentrated at the base in a mylonite zone several tens of meters thick. In this zone, meter-thick dikes rotate into parallelism with the basal thrust and concordant mylonites of both lithologies are intercalated on a centimeter to millimeter scale. The overall rigid block geometry of the Särv thrust sheet, and the intense strain gradient recorded by the rotation of the dike swarm and the concurrent development of mylonites in the thrust zone, suggest that thrust emplacement took place by ductile yield and on-going pseudoplastic flow. Continual strain softening localized ductile flow in this zone by means of grain-size reduction, reaction-enhanced ductility and grain-boundary sliding — processes inferred from the microstructures.