Younger Dryas to Early Holocene paleoclimate in Cantabria (N Spain): Constraints from speleothem Mg, annual fluorescence banding and stable isotope records

The Younger Dryas (YD) stadial represents the most abrupt climate change of the Earth's recent history. Thus, understanding its causes and different local responses is relevant for Quaternary paleoclimatology. We present a speleothem high-resolution proxy record of the Lateglacial to Early Holocene paleoclimate of the Cantabrian Cordillera (N Spain), a strategic location to evaluate the influence of North Atlantic events such as the YD on South-Western Europe. Fluorescence lamination, growth-rate, stable-isotope, and [Mg] records from stalagmite SIR-1 were dated using an age-depth model constrained by U-Th dates and annual-lamina counting. The YD is recorded as a prominent positive delta C-13 excursion whose chronology (12.95 +/- 0.14 to 11.62 +/- 0.16 ka) and shape closely agree with the GS-1 stadial as defined in Greenland ice, supporting the event synchronicity in both areas. A colder and drier YD climate limited soil productivity and dripwater availability, leading to higher delta C-13 and [Mg], reduced growth rate, and virtually absent fluorescence lamination. The early YD record (until similar to 12.5 ka) reflects increasing aridity, whereas the late YD (from similar to 12.2 ka on) shows the opposite trend. At the YD boundaries, temperature changes influenced the [Mg] record by modifying the Mg partition into calcite. However, this effect was superseded by major changes in dripwater Mg/Ca linked to rainfall variations. During the Early Holocene, the Arnero Sierra was forested and had a relatively warm and humid seasonal climate, indicated in SIR-1 by higher growth rates, lower delta C-13 and [Mg], and well-developed fluorescent lamination. Similar to other high-resolution stalagmitic records of the Cordillera, from similar to 8.5 to 8.0 ka SIR-1 reflects a temporary trend of increasing aridity. (C) 2018 Elsevier Ltd. All rights reserved.