Global correlation of the radiolarian faunal change across the Triassic–Jurassic boundary

Abstract

Precise comparison of the change in radiolarian faunas 3.5 m above a U–Pb zircon dated 199.6 ± 0.3 Ma tuff and approximately coincident with a negative δ13C anomaly in the Queen Charlotte Islands, B.C. (Canada) with Inuyama (Japan) sequences indicates that major global changes occurred across the Triassic–Jurassic (T–J) boundary. Nearly 20 genera and over 130 Rhaetian species disappeared at the end of the Triassic. The index genera Betraccium and Risella disappear and the final appearance of Globolaxtorum tozeri, Livarella valida, and Pseudohagiastrum giganteum sp. nov. are also diagnostic for the end of the Triassic. The low-diversity Hettangian survival fauna immediately above the boundary is composed mainly of small, primitive spumellarians with spongy or irregularly latticed meshwork and rod-like spines, and new genera Charlottea, Udalia, and Parahsuum s.l. first appear in the lowest Hettangian in both localities. Irrespective of different sedimentation rates and sedimentary environments, such as shelf to upper slope (Queen Charlotte Islands) and deep sea below carbonate compensation depth (CCD; Inuyama), radiolarians show a similar turnover pattern at the T–J boundary.

An 80 million year oceanic redox history from Permian to Jurassic pelagic sediments of the Mino-Tamba terrane, SW Japan, and the origin of four mass extinctions

“…9), but the next major crisis of radiolarians did not occur until the end of the Triassic. This eliminated 20 genera and over 130 species and the subsequent reduction in bed thickness of basal Jurassic bedded cherts suggests a productivity decline for this group (Carter and Hori, 2005;Hori et al 2007a). However, these changes are not associated with any evidence for lowered oxygen levels and anoxia cannot be implicated in this crisis.…”

Tracking the redox history and nitrogen cycle in the pelagic Panthalassic deep ocean in the Middle Triassic to Early Jurassic: Insights from redox-sensitive elements and nitrogen isotopes

“…Tables 1, 2 and 3. The purple chert corresponds to a horizon of extinct Triassic radiolarians and conodonts (Hori, 1992;Carter and Hori, 2005 Remarkable features of the Katsuyama section are: (1) sub-vertical or bedding-parallel faults within bedded cherts and at the boundaries between siliceous mudstones and turbidites (Figs. 2 and 4A-C), (2) the presence of radiolarian bedded cherts (Figs.…”

Trajectories of Late Permian – Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction

“…Because the Entactinaria dominate most Early Triassic assemblages The trends depicted in Figure 3 confirm previous depictions for the Early Triassic and suggest that the earliest Jurassic also saw a transient and minor rise of entactinarians. The level of our analysis cannot detect ecological responses on finer taxonomic levels and shorter time scales that have been reported from Canada and Japan (Carter & Hori 2005). The moderate increase of entactinarians at the expense of nassellarians is the only indication of an ecological response to the end-Triassic events at this temporal resolution.…”

“…That radiolarians suffered considerable extinctions has long been suggested, based on detailed work on sections in British Columbia and Japan (Hori 1992;Carter 1993Carter , 1994Carter et al 1998;Carter & Hori 2005). However, the statement that nearly 20 genera and over 130 species of radiolarians went extinct (Carter & Hori 2005) needs to be put in context, not only in the context of standing diversity, but also in relation to long-term trajectories of extinction rates.…”

“…However, the statement that nearly 20 genera and over 130 species of radiolarians went extinct (Carter & Hori 2005) needs to be put in context, not only in the context of standing diversity, but also in relation to long-term trajectories of extinction rates. Neither qualitative observations on reductions in test size and architectural complexity (Longridge et al 2007) nor higher estimates on genus extinction (27 according to O'Dogherty et al 2010) suffice to qualify this statement.…”