Milankovitch Cycles Recorded in Terrestrial Mudstones from the Middle to Late Triassic | Bevarade Milankovitch cykler i terrestriska lerstenar från mellersta till sen Trias
2025
Kaplin, Jennifer
This study investigates the relationship between lithology and magnetic susceptibility in loessites from south-west England to examine if orbital forcing is a driving mechanism behind terrestrial climate change of interior Triassic hothouse Pangea. Using magnetic susceptibility and a simple colour analysis, a correlation could be established between lithology and changes in magnetic susceptibility. The magnetic susceptibility signal was analysed with a Fast Fourier Transformation and a Wavelet analysis to determine the cyclicity of change over time. Results showed strong coupling with precession, obliquity and eccentricity, though mostly when the long 400 kyr eccentricity cycle would peak in intensity. Changes in lithology and magnetic susceptibility signal are caused by changes in environment from dry sub aerial desert basin to flooded desert basin under elevated ground water conditions, with lower magnetic susceptibility signals in the waterlogged sediments. These changes in water levels are thought to derive from increase in runoff coupled with a strong monsoonal precipitation. Orbital forcing is determined as a driving mechanism behind these changes, though mostly with high eccentricity within the 400 kyr cycle. It is hypothesised here that the mechanism behind the strong connection to the 400 kyr cycle is the very arid climate of interior Pangea, which makes it hard for the shorter orbital cycles to drive significant shifts in environment without the amplification under enhanced seasonality periods of the long eccentricity cycle.
显示更多 [+] 显示较少 [-]