Preservation of Mesoproterozoic age deep burial fluid signatures, NW Scotland

John Parnell*, Nigel J. F. Blamey, Alessandra Costanzo, Martin Feely, Adrian J. Boyce

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Bedding-parallel fibrous calcite is a widely developed feature of mudrock successions, reflecting conditions of fluid overpressure (Stoneley, 1983, Parnell et al., 2000 and Cobbold et al., 2013). The calcite preserves signatures of fluids developed during deep burial, including hydrocarbons. Most studied examples are of Phanerozoic (<540 Ma) age. This study reports well-preserved fibrous calcite in the Mesoproterozoic (∼1180 Ma) Stoer Group, NW Scotland. The fibrous calcite occurs immediately above a unit of carbonaceous black shale. If hydrocarbons were generated from the black shales, they could have contributed to the development of fluid overpressure, but there is no direct evidence for this. The calcite reflects the original deep burial fluid, rather than a later overprint, because (i) it has a distribution related to stratigraphy, (ii) the bedding-parallel fibres have not been recrystallized, and (iii) later veining is at high angles to bedding. The calcite contains fluid inclusions, and has yielded stable isotope and entrained volatile data, indicating the potential to record diagenetic processes over one billion years ago.
Original languageEnglish
Pages (from-to)275-281
Number of pages7
JournalMarine and Petroleum Geology
Volume55
Early online date8 Dec 2013
DOIs
Publication statusPublished - Aug 2014

Keywords

  • Calcite
  • Diagenesis
  • Mesoproterozoic
  • Oxygenation
  • Precambrian
  • Scotland
  • Stoer group

ASJC Scopus subject areas

  • Economic Geology
  • Geology
  • Geophysics
  • Stratigraphy
  • Oceanography

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