Brucite-driven CO 2 uptake in serpentinized dunites (Ligurian Ophiolites, Montecastelli, Tuscany)

• Published in: Lithos
• Main Authors: Boschi, Chiara, Dini, Andrea, Baneschi, Ilaria, Bedini, Federica, PERCHIAZZI, NATALE, Cavallo, Andrea
• Other Authors: Perchiazzi, Natale
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Paleoclimate; Stable isotopes; Lacustrine succession; Tephrochronology; North Atlantic
• Online Access: http://hdl.handle.net/11568/871251; https://doi.org/10.1016/j.lithos.2017.07.005

Here we present a multiproxy record (δ13C, δ18O, major and minor element composition, mineralogy, and lowresolution biogenic silica content) from a lacustrine succession in the Sulmona Basin, central Italy. Based on previous tephrochronological constraints and a new40Ar/39Ar dating of a tephramatching the widespread X-6 tephra, the record spans the ca. 129–92 ka period and documents at sub-orbital scale the climatic and environmental changes over the Last Interglacial and its transition to the Last Glacial period. The δ18O composition is interpreted as a proxy for the amount and seasonality of local precipitation, whereas variations in elemental andmineralogical composition are inferred to reflect climatic-driven changes in clastic sediment input. The observed variations are consistent among the different proxies, and indicate that periods of reduced precipitation were marked by enhanced catchment erosion, probably due to a reduction in vegetation cover. The first part of the Last Interglacial shows the most negative δ18O values. Comparison with pollen records from the Mediterranean suggests a greater seasonality of the precipitation at this time. At millennial-to-centennial time scales, comparison of the Sulmona record with speleothem δ18O records from central Italy highlights a highly coherent pattern of hydrological evolution, with enhanced variability and similar events of reduced precipitation consistently recorded by each isotope record. The observed intra-interglacial variability can potentially be linked, within the uncertainties associated with each age model, to similar variations observed in sea-surface temperature records from the Mediterranean and the North Atlantic, suggesting a link between Mediterranean hydrology and North Atlantic temperature and circulation patterns that persists during periods of low ice volume.