Abstract

Fractures analysis carried out throughout traverses across Kalosh anticline. The anticline is located ~30 km south of Sulaimaniyah city, Kurdistan region, NE Iraq. It extends NW‒SE for ~17 km within the high folded zone of the northwestern segment of the Zagros Foreland Fold Thrust Belt. The aim of this work is for unraveling the tectonic history and detecting tectonic episodes responded for the initiation and development of the anticlinal structure. More than 450 fracture planes were classified into sets and systems according to their relations with three mutually perpendicular geometric axes (tectonic axes). Tension sets are ac and bc, the first one formed by extension along fold axis accompanying direct compression perpendicular to fold trend, whereas the second is the product of relaxation that motivated the primary compression. The shear systems are hk0, h0l and 0kl developed successively during direct compression and subsequent relaxation episodes of each tectonic force. Field observations and paleostress analysis indicate that the area was subjected to four stress phases. First is primary compressive tectonic phase in the directions NE‒SW. The second compressive tectonic stress in the direction NW–SE considered as a secondary phase. Third was extension tectonic phase in the direction NE–SW which developed during the final uplift stage of folding is normal to the major fold trend. The fourth is NW–SE extension face considerate as extension stress related to the primary NE‒SW compressive stress.

中文翻译：

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伊拉克东北部库尔德地区Kalosh背斜裂缝的古应力分析

摘要

横跨Kalosh背斜的整个导线进行了断裂分析。背斜线位于伊拉克东北部库尔德斯坦地区苏莱曼尼亚市以南约30公里。它在Zagros前陆褶皱冲断带西北段的高褶皱带内向西北延伸约17公里。这项工作的目的是揭示构造历史，并检测对脊背构造的形成和发展作出反应的构造事件。根据450个以上的断裂面与三个相互垂直的几何轴（构造轴）的关系，将其划分为组和系统。张力组为ac和bc，第一个是沿着与垂直于折叠趋势的直接压缩相伴的沿着折叠轴的延伸而形成的，而第二个是引起初级压缩的松弛产物。剪切系统为hk0，h0l和0kl，在每个构造力的直接压缩和随后的松弛过程中相继发展。现场观察和古应力分析表明该区域经历了四个应力阶段。首先是在NE‒SW方向上的主要压缩构造相。在NW–SE方向上的第二个压缩构造应力被认为是次生相。第三是在折叠的最后隆起阶段向NE-SW方向扩展的构造阶段，与主要的折叠趋势垂直。第四个是NW–SE延伸面，被认为是与主要NE‒SW压缩应力有关的延伸应力。现场观察和古应力分析表明该区域经历了四个应力阶段。首先是NE‒SW方向的主要压缩构造相。沿NW–SE方向的第二次构造压应力被视为次生相。第三是在折叠的最后隆起阶段向NE-SW方向扩展的构造阶段，与主要的折叠趋势垂直。第四个是NW–SE延伸面，被认为是与主要NE‒SW压缩应力有关的延伸应力。现场观察和古应力分析表明该区域经历了四个应力阶段。首先是NE‒SW方向的主要压缩构造相。沿NW–SE方向的第二次构造压应力被视为次生相。第三是在折叠的最后隆起阶段向NE-SW方向扩展的构造阶段，与主要的折叠趋势垂直。第四个是NW–SE延伸面，被认为是与主要NE‒SW压缩应力有关的延伸应力。第三是在折叠的最后隆起阶段向NE-SW方向扩展的构造阶段，与主要的折叠趋势垂直。第四个是NW–SE延伸面，被认为是与主要NE‒SW压缩应力有关的延伸应力。第三是在折叠的最后隆起阶段向NE-SW方向扩展的构造阶段，与主要的折叠趋势垂直。第四个是NW–SE延伸面，被认为是与主要NE‒SW压缩应力有关的延伸应力。