Stratigraphic implications of Sinian-Early Cambrian volcanic ash beds on the Yangtze Platform *

U-Pb sensitive high-resolution ion microprobe ages from the Doushantuo Formation in south China: Constraints on late Neoproterozoic glaciations

“…1C; Table DR1 1 ). This ash bed is greenish gray and has been altered to bentonite, mineralogically consisting of illite, mixedlayer illite-smectite, and kaolinite (Zhang et al, 2004). The upper ash bed is found ϳ1.5 m below the Doushantuo-Dengying boundary, slightly below the negative to positive ␦ 13 C shift ( Fig.…”

“…1C; Table DR1 [see footnote 1]) and within the zone in which the Miaohe biota was found (Ding et al, 1996). This ash bed, 3-5 cm thick, is yellowish green and composed of albite, quartz, sanidine, and illitemontmorillonite (Zhang et al, 2004). Both ash beds contain platy and cuspate glass shards, indicating contemporaneous volcanic origin.…”

Mo isotopes in the Lower Cambrian formation of southern China and its implications on paleo-ocean environment

“…Thus, taking the Ni-Mo layer as the PC-C boundary is not appropriate; and (5) bentonites are the result of alteration of volcanic ash that has fallen into the oceans. They are widespread in the Early Cambrian strata, such as in Oman, Canada, Australia, Russia and southern China [24][25][26] . These ash layers can be taken as markers for volcanic eruption events and used for stratigraphic correlation.…”