Upper Paleocene radiolarians from DSDP Sites 549 and 550, Goban Spur, NE Atlantic

Abstract

Upper Paleocene-lower Eocene sequences of mainly pelagic sediments in DSDP Sites 549 11 and 550 of Goban Spur, NE Atlantic, representing time periods of 10 and 6 m.y. respectively, 12 were examined to investigate the biotic response of radiolarians to the PETM. The 13 preservation of radiolarians in the lower Eocene sequences for both sites is poor. Upper 14 Paleocene radiolarian assemblages, representing a time interval of ~ 59-56 Ma at Site 549 15 and a much shorter period at Site 550, are generally moderately well-preserved. Fifty four 16 species were identified. Four species occur significantly earlier in the middle high latitude NE 17 Atlantic than in New Zealand, where the sudden appearance during the PETM has been 18 taken as evidence of global pole-ward migration of warm-water radiolarians. Available 19 model shows that the Goban Spur area should belong to the subpolar surface ocean gyre in 20 the early Paleogene. Thus, our investigation questions the validity of the previously used 21 index species of subtropical warm water masses. High-latitude offshore sections across the 22 P/E boundary with well preserved radiolarians are needed to test the hypothesis of 23 pole-ward migration of warm-water radiolarians during this geologically transient global 24 warming period.

Biostratigraphy and provenance analysis of the Cretaceous to Palaeogene deposits in southern Tibet: Implications for the India‐Asia collision

“…T. larnacium and P. heliastericus are found in ODP 171B and DSDP 10–94, ranging from UAZ JP11 to UAZ JE3 (Jackett et al., 2008). Furthermore, L. auxilla has been described from upper Palaeocene–lower Eocene sediments at DSDP Site 549, NE Atlantic (Liu et al., 2011). The final occurrence of this species constrains the upper limit of the interval of Thanetian to Ypresian (UAZ JE1–JE3; UA11–20) with an absolute age of ca.…”

Diversity dynamics of microfossils from the Cretaceous to the Neogene show mixed responses to events

“…Previous studies have noted a turnover in siliceous groups with warm‐water taxa migrating poleward (Liu et al . 2011; Oreshkina & Radionova 2014), an extinction of cold‐water taxa, and a rapid proliferation of tropical siliceous taxa across the PETM (Mitlehner 1996). It is likely that these previously seen results are not detected here due to the weakness of the silicate record in this interval, reflected in low preservation and sampling rates (Figs 1, 2).…”

“…2020), and the turnover of siliceous taxa at the PETM (Mitlehner 1996; Liu et al . 2011; Oreshkina & Radionova 2014) are three prime examples. The diversification rates for many of the groups reconstructed here are largely static, barring the most major events (Fig.…”

Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the Southwest Pacific

“…These taxa are widely reported in early and middle Eocene sediments but occur in greater abundance in the southwest Pacific at times of global warmth (Hollis, 2006). Liu et al (2011) suggested that these taxa were not valid indicators of high-latitude warming because they are found in the Palaeocene in the North Atlantic. However, their as-sumption that southwest Pacific and North Atlantic Ocean conditions would have been similar in the Palaeogene is not supported by ocean circulation models (Huber et al, 2003(Huber et al, , 2004.…”