Application of anisotropy of magnetic susceptibility to construct the palaeocurrent direction using slender fossil orientations

Abstract

Oriented samples were collected in the southern Mongolia Plateau and north‐eastern Tibetan Plateau to detect links between microstructural features, which are inferred from magnetic fabrics, and outcrop‐scale sedimentary structures that include slender fossil orientations. Palaeocurrent imprints in particles and their recognition in magnetic fabrics depend on the kinetics of current and any post‐depositional reworking. Here, we restored the flooding palaeocurrent direction through the statistical orientation of slender fossils and imprints indicated by magnetic fabric patterns in the sediments. We found that the tilt response of the minimum susceptibility axes preserves more links to the dynamic orientation of fossil deposits, while the maximum susceptibility axes may be easily reworked by a weak but long‐term tectonic compression. Comparing the two methods reveals the correlation between fossil distribution and magnetic fabric. The dynamic identification of anisotropy of magnetic susceptibility on large quantitative samples contributes to provide an alternative way for further statistics of fine‐grained sediments and fabric arrangement.