Fingerprinting fluid source in calcite veins: combining LA-ICP-MS U-Pb calcite dating with trace elements and clumped isotope palaeothermometry

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint.


Download Preprint


John MacDonald, Jacob Van Der Wal, John Faithfull, Adrian Boyce, Nick Roberts, Ian Winkelstern


Application of geochemical proxies to vein minerals - particularly calcite - can fingerprint the source of fluids controlling various important geological processes from seismicity to geothermal systems. Determining fluid source, e.g. meteoric, marine, magmatic or metamorphic waters, can be challenging when using only trace elements and stable isotopes as different fluids can have overlapping geochemical characteristics, such as δ18O. In this contribution we show that by combining the recently developed LA-ICP-MS U-Pb calcite geochronometer with stable isotopes (including clumped isotope palaeothermometry) and trace element analysis, the fluid source of veins can be more readily determined. Calcite veins hosted in the Devonian Montrose Volcanic Formation at Lunan Bay in the Midland Valley Terrane of Central Scotland were used as a case study. δD values of fluid inclusions in the calcite, and parent fluid δ18O values reconstructed from clumped isotope palaeothermometry, gave values which could represent a range of fluid sources: metamorphic or magmatic fluids, or surface waters which had undergone much fluid-rock interaction. Trace elements showed no distinctive patterns and shed no further light on fluid source. LA-ICP-MS U-Pb dating determined the vein calcite precipitation age – 318±30 Ma – which rule out metamorphic or magmatic fluid sources as no metamorphic or magmatic activity was occurring in the area at this time. The vein fluid source was therefore a surface water (meteoric based on paleogeographic reconstruction) which had undergone significant water-rock interaction. This study highlights the importance of combining the recently developed LA-ICP-MS U-Pb calcite geochronometer with stable isotopes and trace elements to help determine fluid sources of veins, and indeed any geological feature where calcite precipitated from a fluid that may have resided in the crust for a period of time (e.g. fault precipitates or cements).



Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics


calcite veins, clumped isotopes, fluid δD and δ18O, LA-ICP-MS U-Pb calcite geochronology, trace elements


Published: 2020-07-15 22:59


CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
please contact the lead author

Add a Comment

You must log in to post a comment.


There are no comments or no comments have been made public for this article.