Regional trends in active diapirism revealed by mountain range‐scale InSAR time series

Abstract

We construct an orogen‐wide InSAR time series over the Zagros Mountains and eastern Markan Subduction Zone in southern Iran from 19 Envisat tracks spanning 2003–2010. We observe active salt diapirism of the infra‐Cambrian Hormuz Salt at 20 locations and identify several diapirs that are not moving. All active diapirs reach the surface within the Asmari Limestone or older rock units while we do not observe any active diapirism occurring within younger exposures, reflecting a complex vertical accumulation of the basal salt and reactivation of diapirs by erosion. Diapir reactivation of this sort may be a critical factor affecting the feasibility of sequestering nuclear waste and CO2 in evaporite sequences over geologic time scales. The distribution of active diapirism is indifferent to increases in mean elevation, suggesting a relatively uniform thickness of the Zagros Fold Belt above the basal salt with steps in topography driven by basement thickening. We do not observe aseismic uplift of anticlines because rates are likely below the detection threshold of our time series. This suggests that uplift is accommodated at small rates (<2–3 mm/yr) over numerous structures instead of focused at the deformation front.