Salt extrusion kinematics: insights from existing data, morphology and InSAR modelling of the active emergent Anguru diapir in the Zagros fold and thrust belt, Iran

Abstract

Emergent salt diapirs are highly mobile geological objects, the kinematics of which pose essential pure and applied problems for geologists and engineers. Movement and deformation of buried salt after its ejection onto the surface is a multivariable process that is susceptible to plenty of intrinsic and ambient factors. As a result, existing data acquisition approaches give extremely variable movement rates for subaerial salt extrusions. The Anguru diapir in the Zagros fold and thrust belt (ZFTB) is a typical emergent intra-anticlinal salt plug that demonstrates very recent activity, and hence was selected to be studied for quantifying salt kinematics under relatively well-defined physical conditions. We used interferometric synthetic aperture radar (InSAR) time-series data to evaluate surface displacement over the salt dome by constructing 236 interferograms derived from 47 Envisat ASAR (time span: 2003–10) and 12 ALOS PALSAR (time span: 2006–10) images, which, combined with other lines of evidence, suggest a very recent extrusion history. The maximum line of sight (LOS) displacement rates of the diapir surface are −2.6 and  +  1.4 cm a−1. Modelling of the Anguru salt plug surface suggests a bilobed pattern of LOS movements that allows interpretation of the interferometric patterns observed over active upwelling (doming) or downwarping structures.Supplementary material: Time series maps of the ALOS 565 ascending track and Envisat 435 descending track interferogramsare available at https://doi.org/10.6084/m9.figshare.c.5413388