“Tiny Wiggles” in the Late Miocene Red Clay Deposits in the North‐East of the Tibetan Plateau

Abstract

Abstract Small amplitude or short period geomagnetic anomalies known as “tiny wiggles” (TWs) are often hard to identify because of magnetic signal smoothing in the marine record of geomagnetic reversals. We report here the late Miocene record of geomagnetic reversals in the aeolian red clay sediments of Linxia Basin in China that enables us to identify two TWs. We performed magnetostratigraphy dating and used spectral analysis to distinguish orbital cycles in the records of magnetic susceptibility (MS) and sedimentary grain size (GS) and develop an orbitally tuned age model. The presence of two TWs in the study section, that correspond to C5n.2n‐3 and C5r.2r‐1, is confirmed by orbital calibration of our age model through recognition of eccentricity, obliquity and precession in MS and GS records.

Keywords

• astronomical calibration
• cyclostratigraphy
• geomagnetic excursions
• magnetostratigraphy
• subchrons
• tiny wiggles