Latest Oligocene to earliest Pliocene deep-sea benthic foraminifera from Ocean Drilling Program (ODP) Sites 752, 1168 and 1139, southern Indian Ocean

Abstract

Abstract. Deep-sea benthic foraminifera provide important markers of environmental conditions in the deep-ocean basins where their assemblage composition and test chemistry are influenced by ambient physical and chemical conditions in bottom-water masses. However, all foraminiferal studies must be underpinned by robust taxonomic approaches. Although many parts of the world's oceans have been examined, over a range of geological timescales, the Neogene benthic foraminifera from the southern Indian Ocean have only been recorded from a few isolated sites. In this study, we have examined 97 samples from Neogene sediments recovered from three ODP sites in the southern Indian Ocean (Sites 752, Broken Ridge; 1139, Kerguelan Plateau; 1168, west Tasmania). These data cover a range of palaeolatitudes and water depths during the Miocene. More than 200 species of benthic foraminifera were recorded at each site and, despite their geographic and bathymetric separation, the most abundant taxa were similar at all three sites. Many of these species range from late Oligocene to early Pliocene demonstrating relatively little faunal turnover of the most abundant taxa during the key palaeoclimatic shifts of the Miocene. We illustrate and document the occurrence of the 52 most abundant species (i.e. those with >1 % abundance) encountered across the three study sites.

Late Miocene Onset of Tasman Leakage and Southern Hemisphere Supergyre Ushers in Near‐Modern Circulation

“…Dickens and Owen (1999), on the contrary, argue that the elevated MARs are the result of a reduction in winnowing and ocean circulation (in line with explanation [2]). Benthic foraminiferal analyses at Site 752 indeed evidence low-oxygen availability throughout this interval (Singh et al, 2012), but high variability in these records (Ridha et al, 2019;Singh et al, 2012) suggests that productivity levels were not constant, or that low-oxygen waters were moving in and out of the region. Furthermore, contrary to expectations under model [2], the OMZ event is less intense at the more northerly 90 E Ridge Site 757 (Dickens & Owen, 1999;Singh et al, 2012).…”

The Knowledge and Application of Sedimentary Conditions of Shallow Marine and Tidal Waters of Ionian Islands, Greece: Implications for Therapeutic Use

“…Sediment underwent wet sieving through 64 µm and 500 µm mesh sieves with tap water and was subsequently oven dried on 40 • C. Foraminifera analysis involved an Optica LAB20 stereoscope for taxonomic identification based on established criteria according to [45,46] (references therein). The categorization of species was performed based on their ecological preferences, drawing from the criteria established by [47,48] and referenced works like [49][50][51][52][53] and references therein. Geochemical analysis of 120 samples (42 samples of mud and 1 sample of sand from the Xi section, 15 samples from Chavdata, 15 samples from Matzavinata, 7 samples from Koutala-Kefalonia Island, 5 samples from Arillas north, 15 samples from Arillas South, and 20 samples from Agios Stefanos) included determining calcium carbonate (CaCO 3 ) and total organic carbon (TOC) content.…”