Abstract
The Neoproterozoic Port Askaig Formation contains widespread pyrite within many diamictite beds, across Scotland and Ireland. The quantity of pyrite is anomalous for coarse-grained rocks, especially in rocks deposited at a time when seawater contained low sulphate levels due to a continental ice cover which inhibited weathering. Sulphur isotope compositions evolve from lightest values (down to -3.1‰) at the base of the formation to highly positive compositions in the overlying Bonahaven Dolomite (mean +44.8‰). This trend is consistent with progressive utilization of available sulphate by closed system microbial sulphate reduction. Together with records from other contemporary diamictite successions, there emerges a picture of global microbial activity during Neoproterozoic ‘Snowball Earth’ glaciation.
| Original language | English |
|---|---|
| Pages (from-to) | 850-854 |
| Number of pages | 5 |
| Journal | Journal of the Geological Society |
| Volume | 174 |
| Early online date | 15 May 2017 |
| DOIs | |
| Publication status | Published - 2017 |
Bibliographical note
AcknowledgementsA.Spencer and K.Mackay helped collect samples on the Garvellach Islands and at Fordyce. I.Fairchild, D. Lowry and G. Shields-Zhou provided valuable criticism. Author contributions: J.P. conceived the project and wrote the paper; A.J.B. performed the isotopic analyses.