Late Cenozoic fluvial-lacustrine susceptibility increases in the Linxia Basin and their implications for Tibetan Plateau uplift

摘要

The variations and mechanisms of fluvial-lacustrine mass-specific magnetic susceptibility (χ) in the northeastern (NE) Tibetan Plateau are complex. In this study, we compiled two Miocene-Pliocene χ records (the Heilinding and Maogou sections, respectively) from the Linxia Basin fluvial-lacustrine sediments, NE Tibetan Plateau to describe the χ increases and discuss their influential factors. The χ in the Heilinding section remained relatively stable at low values before ca. 8.5 Ma, and has increased since ca. 8.5 Ma with strong fluctuations. In the Maogou section the χ increased at ca. 6.0 Ma with relatively weak fluctuations. The mean χ values were higher in the Heilinding section than the Maogou section. The rock magnetic results showed that hematite dominated both sites during the early periods (＞8.5 Ma in the Heilinding and ＞6.0 Ma in the Maogou, respectively), and was replaced by magnetite after that time. Based on the comparison of χ records in Linxia Basin with other magnetic and climate records from the surrounding regions, the χ increase around 8.5-6.0 Ma in the Linxia Basin was mainly driven by tectonics in the northeastern Tibetan Plateau.