Although occupying a critical position at the center of the Mediterranean Sea, the Island of Sardinia (Italy) has never been the focus of multi proxy data-based palaeoclimate studies. An excellent way to obtain information about late Quaternary terrestrial climate oscillations in the region is the study of carbonate speleothems, because they allow the reconstruction of palaeohydrology through the geochemical properties of the their growth layers (Fairchild and Treble, 2009; McDermott, 2004) and are highly suited to accurate independent chronologies (Richards and Dorale, 2003; Scholz et al., 2012). To this end, U-Th series dating, ?18O and ?13C isotope analysis and petrographic observations have been applied to a ~30 cm long stalagmite (BMS1) sampled in the Bue Marino coastal cave (western Sardinia) providing the first palaeoclimate record for this area. Seventeen U-Th ages attest to the formation of BMS1 during MIS5d, between ~110 and ~115 thousand years BP, a period of intense climate perturbations that followed the last interglacial peak (Dansgaard et al., 1993). A positive correlation between ?18O and ?13C, and its correspondence with carbonate fabric variations, reflects variations in drip rate, in turn related to secular variation in the rainfall quantity reaching the cave site during its formation. Furthermore, a hiatus at around 111ky BP marks the interruption of a general isotopic enrichment trend, and probably corresponds to the arrival of a short-lived arid-cold period in the region comparable to a sub-D-O cycles (Capron et al., 2010). The presence of intra millennial climate events has already been reported in Alpine speleothems (Boch et al., 2011) but never in the Mediterranean sea region. For this reason further analyses are planned in order to better understand this variability in Sardinia, that represents an exceptional opportunity to correlate existing and future palaeoclimate records from the peri-Mediterranean European and African mainland.
The first multi-proxy palaeoclimate record (~115ky-110ky) from the Island of Sardinia: implications for the AICC2012 ice-core chronology
Laura Sanna;
2015
Abstract
Although occupying a critical position at the center of the Mediterranean Sea, the Island of Sardinia (Italy) has never been the focus of multi proxy data-based palaeoclimate studies. An excellent way to obtain information about late Quaternary terrestrial climate oscillations in the region is the study of carbonate speleothems, because they allow the reconstruction of palaeohydrology through the geochemical properties of the their growth layers (Fairchild and Treble, 2009; McDermott, 2004) and are highly suited to accurate independent chronologies (Richards and Dorale, 2003; Scholz et al., 2012). To this end, U-Th series dating, ?18O and ?13C isotope analysis and petrographic observations have been applied to a ~30 cm long stalagmite (BMS1) sampled in the Bue Marino coastal cave (western Sardinia) providing the first palaeoclimate record for this area. Seventeen U-Th ages attest to the formation of BMS1 during MIS5d, between ~110 and ~115 thousand years BP, a period of intense climate perturbations that followed the last interglacial peak (Dansgaard et al., 1993). A positive correlation between ?18O and ?13C, and its correspondence with carbonate fabric variations, reflects variations in drip rate, in turn related to secular variation in the rainfall quantity reaching the cave site during its formation. Furthermore, a hiatus at around 111ky BP marks the interruption of a general isotopic enrichment trend, and probably corresponds to the arrival of a short-lived arid-cold period in the region comparable to a sub-D-O cycles (Capron et al., 2010). The presence of intra millennial climate events has already been reported in Alpine speleothems (Boch et al., 2011) but never in the Mediterranean sea region. For this reason further analyses are planned in order to better understand this variability in Sardinia, that represents an exceptional opportunity to correlate existing and future palaeoclimate records from the peri-Mediterranean European and African mainland.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
