High Resolution Chronostratigraphy from an Ice-Dammed Palaeo-Lake in Andorra: MIS 2 Atlantic and Mediterranean Palaeo-Climate Inferences over the SE Pyrenees

This work is close beyond the common applicability of the sequence stratigraphy principles. Nevertheless one aim is to demonstrate its validity for a small ice-dammed palaeo-lake. Since base-level variability is smoothly related with an oscillatory motion, the chronostratigraphy chart emerges as a crucial tool to produce enough quantitative data for a Fast Fourier Transform (FFT) analysis, even if this chronostratigraphy is based on local stratigraphic constraints. The exposed case is related to sixth order stratigraphic cycles, even higher, related to high-frequency global events occurring at the end of the Pleistocene. The glacio-lacustrine record was controlled by an intermittent ice-damming from the main glacier located in Andorra. Tributary glacier tongues advance and retreat accordingly to the main glacier, however asynchronously. The system Tract evolution and the related unconformities reflect the glacier motion imprint. The glacier advances produce an unconformable subglacial till, but also a repeated TST-HST sedimentary evolution over it and their related conformable surfaces. The long-term base-level evolution was leaded by axial tilt cycle, however precession did not appear at the FFT analysis, indicating a strong high latitude climatic influence on the palaeo-lake’s evolution. The sub-orbital periodicities have been observed in the range of the Heinrich events, but also in the range of the Mediterranean salinity anomalies (periodicity of 3–5 ky).