Fig 1.
A. Map showing the major study areas of live (stained) and dead (fossil) benthic foraminifera and ostracods associated to cold-water coral ecosystems: the Norwegian shelf [21–25], the Porcupine Seabight and Rockall Trough [26–30], Nova Scotia [35], the Gulf of Cadiz and Alboran Sea [31, 32], the Ionian Sea [33] and the Tuscan Archipelago [34]. B. Bathymetric map of the Alboran Sea showing the surface-water circulation with the eastern (EAG) and western Alboran gyres (WAG), the Alboran Ridge (AR) and the South Alboran Basin (SAB).
The red star shows the location of core TTR17-401G (251 m water depth) and the green stars the location and water depths of adjacent cores discussed in this study: 1, KS8230 (795 m); 2, TTR12-293G (1840 m); 3, GeoB13731-1 (362 m); 4, TTR17-MS419G (410 m); 5, TTR17-MS411G (370 m); 6, MD95-2043 (1841 m). The dashed areas indicate the location and water depth of cold-water coral samples from the Alboran Sea dated with 14C and U/Th (<20 ka BP): A, Melilla Mounds Field [42]; B, NW Cabliers Bank [43] and C, SE Iberian Margin [44]
Fig 2.
Distribution of main macrofaunal components, benthic foraminifera, benthic foraminifera assemblages (BFA) and ostracods in core TTR17-401G.
The chronology of the core is based on AMS 14C ages of foraminifera and corals and the planktonic foraminiferal turnover (PFT), expressed as a maximum age. The relative abundance of corals and bryozoans is expressed as percentage of the total number of counted macrofauna specimens per sample. The relative abundance of all macrofaunal specimens per sample (black dotted line) is expressed as percentage of the total number of counted specimens in the core. The relative taxonomic richness per sample (red dotted line) is expressed as percentage of the total number of macrofauna taxa found in the core and does not include scleractinian taxa. Benthic foraminiferal species richness (SR) is expressed as the total number of species found in each sample. The dashed lines display changes in the benthic foraminiferal assemblages.
Table 1.
Radiocarbon 14C ages of sediment (benthic foraminifera) and cold-water corals.
All ages are corrected for a reservoir age of 400 years.
Table 2.
Geochemical data of core TTR17-401G.
Are shown total organic carbon (TOC), mineral carbon (MINC), hydrogen index (HI), oxygen index (OI), planktonic (Globigerina bulloides) and benthic (Cibicides lobatulus) δ18O and δ13C, δ13Corg and grain-size distribution.
Fig 3.
Multi-proxy record from core TTR17-401G.
Are displayed the lithology with main macrofaunal components, radiocarbon ages of sediment (foraminifera), grain-size distribution (<63 μm), total organic carbon (TOC), δ13Corg, δ13C and δ18O of benthic and planktonic foraminifera. Benthic foraminiferal assemblages (BFA) are shown according to the level of the Bray-Curties Similarity: BFAni and BFAgi (39%) and BFA1-BFA4 (54%). Dashed line indicates the turnover in the planktonic foraminiferal assemblage (PFA) at ca. 8 ka BP [79]. Freshwater pulses 1–4 correspond to possible freshening events of the (sub-) surface waters.
Fig 4.
Relative abundances of selected epibenthic and infaunal benthic foraminifera.
Mineral carbon (MINC) content and P/B ratio are plotted against the benthic foraminiferal assemblages (BFA). The dashed line indicates the planktonic foraminiferal turnover [79].
Fig 5.
Pseudo-Van Krevelen HI versus OI plots showing the distribution of samples from core TTR17-401G and S2 versus Total organic carbon (TOC) diagrams for samples BFA1-BFA2 and BFA3-BFA4.
Regression curves are also shown for each diagram. Boundaries between the kerogen type fields are from Langford and Blanc-Valleron [80].
Fig 6.
Hierarchical dendrogram based on the Bray-Curties similarity matrix of benthic foraminiferal compositional dataset from core TTR17-401G.
Two clusters are separated at 39% of similarity (BFAgi and BFAni). At 54% of similarity, four clusters can be recognized (BFA1, BFA2, BFA3 and BFA4).
Fig 7.
Sketch showing the evolution of cold-water corals in the MMF in the last 13 ka.
The time frame and the paleoceanographic conditions are inferred from radiocarbon dating, benthic foraminiferal assemblages BFA1-4, macrofaunal data, benthic and planktonic δ18O and δ13C, Rock-Eval pyrolisis and δ13Corg. Climatic and oceanographic settings included in the sketch are Atlantic Water (AW) inflow, Modified Atlantic Water (MAW), Leventine Intermediate Water (LIW), relative sea level, strength and position of the pycno-nutricline, humidity in the northern African hinterland, sediment load to the shelf, regeneration and upwelling of nutrients (e.g., phosphorus), terrigenous (TOM) and marine organic matter (MOM) and bottom water (BW) ventilation.
Fig 8.
Multi-proxy record versus age.
Including: a) excess 230Th normalized fluxes of terrigenous material at ODP Hole 658C [128], b) salinity reconstruction at KS8230 [129], c) planktonic δ18O (Globigerina bulloides) at MD95-2043 [114], d) glacio-hydro eustatic model for the western Mediterranean Sea [86], e) planktonic δ18O (Globigerinoides ruber var. alba) at MS27PT [130], f) benthic δ18O (Cibicides kullenbergi) at GeoB13731-1 [42], g) Al-normalized concentrations of Ba (Ba/Al) at TTR12-293G [106]. At the lower panel are displayed the ages of corals dated in the Alboran Sea. The grey dashed areas indicate possible periods of interruption of CWC growth during the last 14 ka in the Alboran Sea.
Fig 9.
Depth versus age plot for cold-water coral samples from core TTR17-401G.
Displayed are vertical mound aggradation rates. Dashed areas (grey) indicate sustained CWC growth at the Melilla Mounds Field (MMF). The panels (purple) show cold-water coral growth periods in the MMF based on radiocarbon ages of cold-water corals from Fink et al. [42] and their respective vertical mound aggradation rates.