High-frequency climate fluctuations over the last deglaciation in the Alboran Sea, Western Mediterranean: Evidence from calcareous plankton assemblages

Holocene climate variability of the Western Mediterranean: Surface water dynamics inferred from calcareous plankton assemblages

“…11.5 ka, it appears unlikely that excess precipitation was the driving force of the ORL1 formation in the Western Mediterranean (Rogerson et al, 2008). As stated in Bazzicalupo et al (2018), shoaling of the nutricline and increased export production at the sea floor are relevant mechanisms in the ORL1 deposition at the study core.…”

“…This phase straddles the early Holocene, between 11.5 and 8 ka and is subsequent to the Younger Dryas Stadial. The climate evolution of the latter stadial has been discussed in detail in Bazzicalupo et al (2018), based on the same proxies and therefore not discussed in this study. Phase I is marked by a gradual surface water temperature increase, well described by progressively growing abundances of both coccolithophore and foraminifera warm-water taxa, associated with increasing summer insolation (Figure 5).…”

“…Syracosphaera spp. has been, in fact, related to enhanced supply of fresher and turbid upper layer (Ausín et al, 2015b; Bazzicalupo et al, 2018; Colmenero-Hidalgo et al, 2004; Weaver and Pujol, 1988), while the cold taxon T. quinqueloba flourishes in high-fertile and low-density surface waters (Aksu et al, 2002; Hemleben et al, 1985; Pujol and Vergnaud-Grazzini, 1995; Triantaphyllou et al, 2010). Enhanced abundances of this taxon have also been related to areas influenced by continental runoff (Bartels-Jónsdóttir et al, 2015; Girone et al, 2013; Jonkers et al, 2010; Margaritelli et al, 2016; Rohling et al, 1997; Vallefuoco et al, 2012) and, in the Eastern Mediterranean, the increase in abundance of T. quinqueloba , during the deposition of sapropel layer S1, has been linked to a high tolerance for low salinity and highly stratified water conditions coupled with the presence of high nutrients and terrestrial organic material (Capotondi et al, 2004; Kontakiotis, 2016; Principato et al, 2006; Rohling et al, 1997; Zachariasse et al, 1997).…”

“…Deep anoxia in the western basin is in fact independent of that of the eastern basin (Rogerson et al, 2008) and ORL1 termination is related to the 8.2 ka event and to the establishment of the modern front-dominated conditions in the Western Mediterranean (Cacho et al, 2002; Rogerson et al, 2008). During Phase II, differently from Phase I occurring during ORL1 deposition and characterized by shoaling of the nutricline and enhanced productivity in surface water (Bazzicalupo et al, 2018), the calcareous plankton assemblages indicate stratified conditions in column water and deep nutricline, which likely prevented productivity in surface water and export production at the sea floor. This datum supports the hypothesis that productivity, although does not represent the triggering mechanism, may provide a secondary control in the ORL formation (Rogerson et al, 2008).…”

“…During phase II, differently from phase I occurring during ORL1 deposition and characterized by shoaling of the nutricline and enhanced productivity in surface water (Bazzicalupo et al, 2018), the calcareous plankton assemblages indicate stratified conditions in column water and deep nutricline, which likely prevented productivity in surface water and export production at the sea floor. This datum supports the hypothesis that productivity, although does not represent the triggering mechanism, may provide a secondary control in the ORL formation (Rogerson et al, 2008).…”