Abstract
Pyrite is consistently found in modern seafloor vesicular basalts and has a sulphur isotopic composition consistent with microbial activity. We present S isotope data from pyrite in Ordovician pillow lavas at localities across the British Isles, which yield a range of δ34S compositions consistent with two components of sulphur: groundmass pyrite (~0±4‰) and 32S-enriched pyrite in the vesicles (-8‰ to -27‰). The latter are recorded from vesicular lavas in four different terranes, representing different settings at the margins of the Iapetus Ocean. Whereas a component of magmatic sulphate is recognized in the groundmass values, the isotopically light data in the vesicles are consistent with microbial reduction of seawater sulphate in sub-seafloor lavas. This is consistent with modern examples and indicates considerable longevity for this sub-seafloor microbial habitat.
Original language | English |
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Pages (from-to) | 497-508 |
Number of pages | 12 |
Journal | Geological Journal |
Volume | 50 |
Issue number | 4 |
Early online date | 15 May 2014 |
DOIs | |
Publication status | Published - 1 Jul 2015 |
Keywords
- Basalt
- Deep biosphere
- Ireland
- Ordovician
- Pillow lava
- Scotland
- Wales