Holocene hydrography evolution in the Alboran Sea: a multi-record and multi-proxy comparison

Abstract

Abstract. A new high-resolution deglacial and Holocene sea surface temperature (SST) reconstruction is presented for the Alboran Sea (western Mediterranean), based on Mg∕Ca ratios measured in the planktonic foraminifera Globigerina bulloides. This new record is evaluated by comparison with other Mg∕Ca SST records and previously published alkenone SST reconstructions from the same region for both the Holocene and glacial periods. In all cases there is a high degree of coherence between the different Mg∕Ca SST records but strong discrepancies when compared to the alkenone SST records. We argue that these discrepancies are due to differences in the proxy response during deglaciation which we hypothesize to reflect a resilience strategy of G. bulloides, changing its main growth season, and consequently Mg∕Ca records a shorter deglacial warming than alkenones. In contrast, short-term Holocene SST variability is larger in the Mg∕Ca SST than in the alkenone SST records. We propose that the larger Mg∕Ca SST variability is a result of spring temperatures variability, while the smoothed alkenone SST variability represents averaged annual temperatures. The Mg∕Ca SST record differentiates the Holocene into three periods: (1) the warmest SST values occurred during the Early Holocene (11.7–9 cal. kyr BP), (2) a continuous cooling trend occurred during the Middle Holocene that culminated in the coldest Holocene SST having a double cold peak structure centred at around 4.2 cal. kyr BP, and (3) the Late Holocene (4.2 cal. kyr BP to present) did not follow any clear cooling/warming trend although millennial-scale oscillations were enhanced. This SST evolution is discussed in the context of the changing properties in the Atlantic inflow water associated with North Atlantic circulation conditions and also with local hydrographical and atmospheric changes. We propose that a tight link between North Atlantic circulation patterns and the inflow of surface waters into the Mediterranean played a major role in controlling Holocene climatic variability of this region.

Environmental Changes and Cultural Transitions in SW Iberia during the Early-Mid Holocene

“…Sea surface temperature decreased in the Gulf of Cádiz [75] and Alborán Sea [76], and this change correlates with the increase in the organic matter content of core 19-01 (Figure 6d).…”

“…Thus, it seems possible that the observed abrupt changes in the geochemical record of core 19-01 can be related to those palaeoceanographic changes, while the gradual ones are interpreted to link to terrestrial climate variations. [83]; Ria Formosa [84]; Algarve and Central Portugal [74] and global [85] and Zr/Rb ratio (notice the reversed scale); (c) sea surface temperature (SST) reconstructions for the Gulf of Cádiz (alkenone Uk37 SST derived for core M39-008 [75]) and Mg/Ca SST derived for the Alborán Sea (ALB2 [76]); (d) Ti, Fe, and Mn, weathering proxies, as indicative of land moisture; (e) Al, Si, Sr and Ca, representative of clastic sedimentation, serve as proxies for activity of marine currents; (f) Ca/Si, carbonate vs. siliciclastics, and Zr/Al and Si/Al, proxies of siliciclastic grains vs. matrix, as indicative of land derived vs. bioclastic (marine) inputs; (g) sedimentation rate for core 19-01 for the 12-6 ka BP period.…”

Chronology, time averaging, and oxygen isotope composition of harvested marine mollusk assemblages from Ifri Oudadane, northeast Morocco

“…Lorenz and Lohmann (2004) suggest that orbital changes in insolation represent one of the primary drivers of SST variability in the Alboran Sea. Català et al (2019) argue that orbital changes in insolation can only account for ~1.6°C of the 5°C or greater climate variability that is seen throughout the Holocene. Instead, Català et al (2019) propose that mixing of water masses through the Straits of Gibraltar impact temperature changes in the area in combination with orbital changes in isolation.…”

4° Convegno dei Geologi Marini Italiani

“…Nel Mediterraneo, questo evento è documentato in pochissimi records (i.e, Di Rita & Magri, 2009;Margaritelli et al, 2016;Di Rita et al, 2018;Bini et al, 2019;Català et al, 2019) ma non è ancora chiaro se, nelle successioni marine, ci siamo eventi bio-stratigrafici utili a vincolare e / o approssimare questo GSSP.…”