The nature of non-evaporite intrasalt stringers in Witchelina salt diapir, Flinders Ranges, South Australia

Stringers in salt diapirs are fragments (clasts) of competent lithologies commonly sourced from a layered evaporite sequence (LES) that are entrained and deformed by viscous flow, though they can also be incorporated at suture zones and as encapsulated minibasins. The LES typically comprises interbedded weaker layers (e.g., halite and bittern salts) and stronger layers (anhydrite and non-evaporite rocks such as carbonates and siliciclastics). Previous work aiming to understand the deformation of stringers and the impacts of stringers on salt flow has mostly utilized a combination of data from conceptual, numerical, and analog models as well as seismic interpretation. These sources of data fail to provide details of stringer deformation and thus, it remains unclear if/how the lithology of LES/stringers provide a first order control on the transport and concentration/localization of stringers in mobile salt. Understanding these features is of interest to academia and industry because the preservation and distribution of stringers provide constraints on how we interpret fluid interactions and sealing compacity internally and surrounding mobile salt. Determining whether the character of salt stringers relates to the diagenetic history and alteration of internal salt materials and near diapir sediments can elucidate whether we should expect alteration of salt-adjacent chemostratigraphic records and the concentration of critical minerals within salt bodies as well as in the adjacent salt stratigraphy.

Here we provide sedimentologic, stratigraphic, geochemical, and satellite-based remote sensing data from the oblique cross-sectional exposure of the Precambrian Witchelina LES transitioning to a steeply rising salt diapir and ultimately an allochthonous sheet. Our data provides constraints on the distribution of mechanically different intrasalt stringer lithologies at the sub-seismic scale.