Tracing the "missing shortening" in fold-and-thrust belts: Insights from structural analyses of the Hotan-Mazatagh transect in the West Kunlun foreland, NW China

Use of balanced cross-section methods, which assume length and area conservation in two dimensions, to quantitatively analyze fold -and -thrust belts is vital in structural analyses. However, layer -parallel shortening is beyond this assumption and thus indescribable by balanced cross-section methods. The contribution of layer -parallel shortening in accommodating shortening has rarely been quantitatively determined, especially in sections hundreds of kilometers in scale. In this study, we conducted structural analyses on the -230-km-long Hotan-Mazatagh transect along the West Kunlun foreland of the NW Tibetan Plateau, based on interpretations of seismic reflection profiles. The results reveal that the transect forms a long thrust sheet detaching along the basal Cenozoic detachment, with deformation localized in the Hotan, Manan, and Mazatagh belts. Out of the -23.82 km of cutoff displacement translating into the thrust sheet, only -1.4 km and -4.94 km are absorbed by the Hotan anticline and the Mazatagh detachment thrust, respectively. The remaining -17.48 km extent of shortening is absorbed by layer -parallel shortening in the -180-km-long section between the Hotan and Mazatagh belts. The layer -parallel shortening produces a strain rate of -2.43 x 10-8 yr-1 and absorbs -77.97% methods, conservation analyze structural shortening indescribof the shortening of the segment. Our results argue for caution when using balanced crosssection methods to determine deformation magnitudes. We suggest that localized deformation and layer -parallel shortening function together to shape the -230-km-long HotanMazatagh transect into a combined discreteand -distributed deformation style.