10.6084/m9.figshare.3454967.v1
John Parnell
John
Parnell
Darren Mark
Darren
Mark
Anthony E. Fallick
Anthony E.
Fallick
Adrian Boyce
Adrian
Boyce
Scott Thackrey
Scott
Thackrey
The age of the Mesoproterozoic Stoer Group sedimentary and impact deposits, NW Scotland
Geological Society of London
2016
ejecta blanket
Mesoproterozoic Stoer Group
impact ejecta deposit
impact deposits
Stac Fada Member
lake water
palaeomagnetic data
1180 Ma
Fluid inclusion analysis
degassing structures
Ar
NW Scotland
Geology
2016-06-21 12:28:36
Dataset
https://geolsoc.figshare.com/articles/dataset/The_age_of_the_Mesoproterozoic_Stoer_Group_sedimentary_and_impact_deposits_NW_Scotland/3454967
<p>The Mesoproterozoic Stoer Group of the ‘Torridonian' has been dated at 1177 ± 5 Ma (2σ), based on <sup>40</sup>Ar/<sup>39</sup>Ar dating of authigenic K-feldspars precipitated in degassing structures within the Stac Fada Member, interpreted previously
as an impact ejecta deposit. Fluid inclusion analysis of the K-feldspar shows that it precipitated from hot fluids, and so
must immediately post-date emplacement of the ejecta blanket. The oxygen isotopic composition of K-feldspar is remarkably
constant at 9.7 ± 0.2‰ (V-SMOW) and is consistent with derivation from evaporated lake water. The new age supports previous
determinations of 1199 ± 70 Ma from Pb–Pb dating of limestone and 1180 Ma from palaeomagnetic data, but provides much higher
precision.
</p>