Fig. 7: Spectral analysis.
From: Dry hydroclimates in the late Palaeocene-early Eocene hothouse world
Power spectra (periodograms in the 1st and 2nd rows), squared coherency spectra (3rd row) and phase spectra (4th row) for PC1dis and hard isothermal remanent magnetisation in a carbonate free basis (HIRM-CFB) for different Contessa Road intervals. a The Palaeocene-Eocene Thermal Maximum (PETM), b the post early Eocene terrigenous zone-pre early Eocene low magnetisation zone (post EETZ-Pre EELMZ) and c the post early Eocene low magnetisation zone (EELMZ) define the intervals in which spectral analyses were carried out. 90% and 95% confidence levels in periodograms are indicated by sky blue and dark blue lines, respectively. False alarm levels α = 0.10 and 0.05 in squared coherency spectra are indicated by sky blue and dark blue dashed lines, respectively. Black shapes in phase spectra represent lag/lead relationships of PC1dis with respect to HIRM-CFB. Maximum and minimum lag/lead relationships are indicated in kyr by numbers next to black shapes in phase spectra. Associated frequencies of short eccentricity and precession are indicated by dark grey and light grey bands, respectively. Short eccentricity (~100 kyr) and precession (~22 kyr) periods are related to spectral peaks over the 90%-95% confidence levels.
