Glacial–interglacial cycles in the south-central and southeastern Pyrenees since ~180 ka (NE Spain–Andorra–S France)

Abstract

This study uses luminescence and 14C accelerator mass spectrometry procedures to date relevant glaciofluvial and glacial deposits from the south-central and southeastern Pyrenees (Andorra–France–Spain). We distinguish two types of end-moraine complexes: (1) those in which at least a far-flung moraine exists beyond a frequently nested end-moraine complex (the most common) and (2) those in which a close-nested end moraine encompasses at least two glacial cycles. Both types formed within six distinctive glacial intervals: (1) A penultimate glacial cycle during Marine Oxygen Isotope Stage (MIS) 6 and older glaciofluvial terraces occurred beyond the range of the luminescence dating method. (2) An early glacial advance in MIS 5d (~97 −15/+19 ka) was followed by glacial retreat during MIS 5c (< 91 ± 9 ka). (3) The last maximum ice extent (LMIE) was in early MIS 4 (~74 ± 4.5 ka). (4) Unexpectedly, glaciers thinned during the second half of MIS 3 (~39 −6/+11 ka). (5) During the MIS 3–2 transition, glaciers subsequently fluctuated behind the LMIE limits. (6) The global last glacial maximum (LGM) started as early as ~26.6 ± 0.365 ka b2k, and the corresponding end moraines were built behind the LMIE limits or merged with it, forming close-nested moraines.

The mid‐latitude hydrolaccolith of the Spanish Central System (Southern Europe): A top‐to‐bottom integration of geomatic, geophysical and sedimentary datasets for characterising a singular periglacial landform

“…This climate pattern also coincides with the innermost moraine built-up at Hoyo Grande (Carrasco et al, 2016), a mid-Holocene neoglacial episode in the northern slope of the Pyrenees (Cirque de Troumouse; Gellatly et al, 1992) and the eustatic sea level fall across the Iberian margins between ≈6.0 and 3.8 ka (Hernández- Molina et al, 1994). At the hemispheric scale, the appearance of the Calderuelas hydrolaccolith is contemporaneous with the onset of the so-called 4.2 ka Event, which has been generally associated with intense droughts and colder conditions around the Mediterranean basin (Bini et al, 2019) occurring each 4.5 ± 0.5 ka (Hernández- Molina et al, 1994;Turu, 2023;Turu et al, 2023). The chronology of these long-range climate oscillations is in line with the formation of the Calderuelas hydrolaccolith, and, therefore, we interpret that the latter occurred under progressively drier conditions and slightly colder temperatures potentially enhanced by local topoclimatic factors.…”