Figure 3

Pore water sulfate concentration and geochemical characterization of gravity cores 1145GC (a), 1143GC (b) and 1174GC (c). X-Ray Fluorescence profiles of barium (Ba), calcium (Ca), sulfur (S) along the three cores are compared with TOC/TS values and δ¹³C and δ¹⁸O composition of foraminiferal tests and one MDAC sample (core 1143GC) in order to constrain AOM-impacted sediment intervals. Barium peaks at 163 cm and 175 cm in 1143GC are analytical artifacts due to the presence of voids on core surface at the bottom of the core. SEM–EDS observations of foraminifera are also reported, from top to bottom: Cassidulina neoteretis, Cassidulina reniforme, Melonis barleeanum and undetermined foraminifera (high degree of alteration). Solid vertical line in the TOC/TS plots indicates the threshold value 2.8 used to distinguish background TOC/TS values (> 2.8)⁴² from AOM-impacted sediment intervals marked by an excess sulfur (TOC/TS < 2.8)^43,48. Vertical shaded area (light blue color) in the δ¹⁸O plots indicate the usual range for unaltered foraminiferal tests^45,47. The location of the modern SMTZ is highlighted with a horizontal red area (b, c), whereas paleo-SMTZs are reported in grey color. M/I = mica/illite; Q + F = quartz + feldspars; A = aragonite. (The reader is referred to the Web version of this article for interpretation of the references to color in this figure legend).