chert nodules as meso scale shear sense indicators; case studies in zagros hinterland fold-and-thrust belt, iran

This study is the first investigation which introduces deformed chert nodules—such as rotated spherical nodules, sigmoid-shaped inclusions, and stair-stepping strain shadows around nodules—as reliable mesoscale shear sense indicators. in addition, it highlights the novel use of asymmetric folded chert layers as kinematic indicators. these features were systematically analyzed in the well-established shear zones of the zagros hinterland fold-and-thrust belt (zhtb), ne of the sanandaj-sirjan metamorphic belt, providing new insights into the tectonic processes. the innovative aspect of this research lies in the detailed investigation of chert structures, which have not been extensively considered as shear sense indicators in ductile shear zones until now. the findings present a breakthrough in geodynamic studies by offering a new method for determining shear sense in regions where traditional indicators are scarce or difficult to observe.