Deformation style associated with the early stage of subduction of the Neo-Tethys under Iranian microcontinent is poorly understood. Utilizing field observations, microscopic thin-section interpretation, and recently published ⁴⁰Ar-³⁹Ar ages, we conducted a structural analysis of the North Shahrekord Shear Zone. The study area is located in the central Sanandaj-Sirjan Zone in western Iran, in an area that includes high-grade eclogite-bearing and low-grade metamorphic units of the North Shahrekord Metamorphic Complex. Two generations of deformation were observed in the study area, including D1 and D2. D1 structures are rare and involve folds and axial-plane foliations (S1), which have been almost obliterated by D2. D2 is characterized by a dextral transpressional zone, where strain is partitioned into distinct simple shear and pure shear domains. The pure shear domain is observed mainly in low-grade zone and some high-grade metamorphic rocks, and is characterized by NW-striking close to isoclinal folds (F2) and axial-plane foliations (S2). Folds are mostly inclined and their vergence is towards the southwest and northeast in the northern and southern parts of the study area, respectively. In the central part of the area, F2 includes approximately upright folds. These mesoscopic folds are associated with map-scale folds. The simple shear domain is restricted to the high-grade metamorphic rocks of the North Shahrekord Shear Zone, defined by NW-striking steeply dipping mylonitic foliation with low-angle stretching lineation. Kinematic indicators, such as quartz sigmoids, feldspar porphyroclasts, mica fish, and C- and C′-type shear bands, reveal a dextral strike-slip movement with a minor reverse component along the North Shahrekord Shear Zone. Recrystallized phengite from mylonitic eclogite and metagranite have been recently dated (⁴⁰Ar-³⁹Ar) at 178–170 Ma and ~110 Ma, respectively, indicating that the Sanandaj-Sirjan Zone was dominated by dextral transpression phases in the Early-Middle Jurassic and Early Cretaceous. The transpressional phases are interpreted to have occurred in response to the oblique subduction of the Neo-Tethys Ocean under the Iranian microcontinent.

与伊朗微大陆下新特提斯洋俯冲早期阶段相关的变形方式知之甚少。利用现场观察、显微薄片解释和最近发表的⁴⁰ Ar- ³⁹Ar Ages，我们对 North Shahrekord 剪切带进行了结构分析。研究区位于伊朗西部的中部 Sanandaj-Sirjan 地带，该地区包括 North Shahrekord 变质杂岩的高品位榴辉岩和低品位变质单元。研究区观察到两代变形，包括D1和D2。D1 结构很少见，涉及褶皱和轴面叶理 (S1)，这些结构几乎已被 D2 抹去。D2 的特点是右旋压区，其中应变被划分为不同的简单剪切域和纯剪切域。纯剪切域主要在低品位带和一些高品位变质岩中观察到，以接近等斜褶皱（F2）和轴面片理（S2）的NW走向为特征。研究区北部和南部的褶皱大多呈倾斜状，辐合分别向西南和东北方向。在该区域的中心部分，F2 包括近似直立的褶皱。这些细观褶皱与地图尺度褶皱相关。简单剪切域仅限于 North Shahrekord 剪切带的高级变质岩，由 NW 走向的陡倾糜棱片理定义，具有低角度拉伸线理。运动学指标，如石英 sigmoids、长石斑岩碎屑、云母鱼和 C-和 C'-型剪切带，揭示了沿北沙赫里科德剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶出的菱镁矿已确定年代（在该区域的中心部分，F2 包括近似直立的褶皱。这些细观褶皱与地图尺度褶皱相关。简单剪切域仅限于 North Shahrekord 剪切带的高品位变质岩，由 NW 走向的陡倾糜棱片理和低角度拉伸线理定义。运动学指标，如石英 sigmoids、长石斑岩碎屑、云母鱼和 C-和 C'-型剪切带，揭示了沿北沙赫里科德剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶的 phengite 已确定年代（在该区域的中心部分，F2 包括近似直立的褶皱。这些细观褶皱与地图尺度褶皱相关。简单剪切域仅限于 North Shahrekord 剪切带的高品位变质岩，由 NW 走向的陡倾糜棱片理和低角度拉伸线理定义。运动学指标，如石英 sigmoids、长石斑岩碎屑、云母鱼和 C-和 C'-型剪切带，揭示了沿北沙赫里科德剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶的 phengite 已确定年代（简单剪切域仅限于 North Shahrekord 剪切带的高品位变质岩，由 NW 走向的陡倾糜棱片理和低角度拉伸线理定义。运动学指标，如石英 sigmoids、长石斑岩碎屑、云母鱼和 C-和 C'-型剪切带，揭示了沿北沙赫里科德剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶的 phengite 已确定年代（简单剪切域仅限于 North Shahrekord 剪切带的高品位变质岩，由 NW 走向的陡倾糜棱片理和低角度拉伸线理定义。运动学指标，如石英 sigmoids、长石斑岩碎屑、云母鱼和 C-和 C'-型剪切带，揭示了沿北沙赫里科德剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶的 phengite 已确定年代（揭示了沿 North Shahrekord 剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶的 phengite 已确定年代（揭示了沿 North Shahrekord 剪切带具有轻微反向分量的右旋走滑运动。最近从糜棱榴辉岩和变花岗岩中重结晶的 phengite 已确定年代（⁴⁰ Ar- ³⁹ Ar) 分别在 178-170 Ma 和 ~110 Ma，表明 Sanandaj-Sirjan 带在早-中侏罗世和早白垩世以右旋压相为主。挤压阶段被解释为响应伊朗微大陆下新特提斯洋的倾斜俯冲。