The age of the Nantuo Formation and Nantuo glaciation in South China

Abstract

A U–Pb sensitive high‐resolution ion microprobe (SHRIMP) age of 654.5 ± 3.8 Ma from an ash bed immediately below the Nantuo Formation in South China provides the lowest age constraint for the Nantuo glaciation, which has been correlated with the global ‘Marinoan’ glaciation. A U–Pb SHRIMP age of 636.3 ± 4.9 Ma from a fallout tuff within the basal layer of the Nantuo Formation, along with the existing age of 635.2 ± 0.6 Ma from its overlying Doushantuo cap carbonate, suggests that the traditionally defined Nantuo Formation may have been deposited in a short time period at the end of the Nantuo glaciation. In combination with available ages globally, the data support a relatively short duration and rapid termination of ‘Marinoan’ glaciations.

A composite C-isotope profile for the Neoproterozoic Dalradian Supergroup of Scotland and Ireland

“…Marinoan glacial-cap carbonate sequence (Kennedy 1996;Kennedy et al 1998;Hoffman et al 1998;Hoffmann & Schrag 2002;Hoffmann et al 2004;Halverson et al 2002Halverson et al , 2005Condon et al 2005;Zhang et al 2008); and (iii) the late Neoproterozoic Wonoka-Shuram anomaly (Burns & Matter 1993;Calver 2000;McKirdy et al 2001;Fike et al 2006;Le Guerroué et al 2006;Rieu et al 2007). Our data provide, for the first time, globally comparative C-isotope events through the Dalradian.…”

“…UPb zircon ages on ash beds that date the meltback phase and the formation of the cap carbonate of this glaciation yield an age of 635 Ma for these events (Hoffmann et al 2004;Condon et al 2005;Zhang et al 2008). …”

The Late Cryogenian Warm Interval, NE Svalbard: Chemostratigraphy and genesis

“…Dates for the onset of Marinoan glaciation are less constrained. U-Pb ages of 654.5 ± 3.8 Ma and 636.3 ± 4.9 Ma from tuffs immediately below the Nantuo Formation, and within the Nantuo Formation in South China (Zhang et al, 2008) respectively, provide the tightest age constraints on the onset of Marinoan glaciation. In summary, current knowledge from radiometric dating suggests the mid-Cryogenian glacial interval represents the time between c. 663-659 Ma and c. 654-636 Ma, a duration of between 5 and 27 My.…”

“…Likewise, the basal, globally correlated cap carbonate to the Marinoan glaciation, which defines the Cryogenian-Ediacaran boundary, is well-constrained to ca. 635 Ma based on radiometric ages in China (Condon et al, 2005;Zhang et al, 2008), Namibia (Hoffmann et al, 2004), Tasmania (Calver et al, 2013) and NW Canada (Re-Os date; Rooney et al, 2015). Both early and late Cryogenian glaciations, referred to as the Sturtian and Marinoan (based on locations in South Australia), respectively, appear to be globally distributed (Li et al, 2013).…”

Geochemical constraints on the origin of Doushantuo cap carbonates in the Yangtze Gorges area, South China

“…B: A conceptual transect (a-a′ in A; not to scale) across the Yangtze block showing the stratigraphic occurrence of the Doushantuo cap carbonates (Jiang et al, 2003a, b). Age data are from Condon et al (2005) and Zhang et al (2008). C: Simplified geological map of the Yangtze Gorges area (Zhao et al, 1985).…”