Lairg Gravity Low
| Lairg gravity low | |
|---|---|
| Scotland crater | |
  Lairg gravity low Approximate location of the Lairg gravity low | |
| Impact crater/structure | |
| Confidence | Probable |
| Diameter | 40 kilometres (25 mi) |
| Age | 1200 Myr Mesoproterozoic |
| Exposed | No |
| Drilled | No |
| Location | |
| Location | Lairg, Scotland |
| Coordinates | 58°1′12″N 4°24′0″W / 58.02000°N 4.40000°W |
| Country | Scotland |
| Province | Sutherland |
The Lairg gravity low is a suspected impact crater in Scotland about 40 kilometres in diameter, with a centre near the town of Lairg in the Scottish Highlands. Its identity as an impact crater is suspected due to the impact deposits present in the Stac Fada Member 50 km to the west.[1]
Description
Relative to the residual gravity field, at the centre it is 23 mgal lower than the surrounding terrain. The gravity anomaly is approximately 40 km across, and somewhat irregularly shaped towards the edges. It is quite similar to that of the Ries impact crater.[citation needed]
Correlation to the Stac Fada Member
It is suspected that the Lairg site is the source of the ejecta deposits in the Stac Fada Member for a number of reasons. The palaeocurrent direction data across the N-S extent of the member changes and always points away from the site of the gravity low. The upper levels of target sediment were unconsolidated sand and basement felsic gneiss, according to the lithic fragments in the member.[2]
References
- ^ Amor, Kenneth; Hesselbo, Stephen P.; Porcelli, Don; Thackrey, Scott; Parnell, John (2008). "A Precambrian proximal ejecta blanket from Scotland". Geology. 36 (4): 303. doi:10.1130/G24454A.1. ISSN 0091-7613.
- ^ Simms, Michael J. (2015). "The Stac Fada impact ejecta deposit and the Lairg Gravity Low: evidence for a buried Precambrian impact crater in Scotland?". Proceedings of the Geologists' Association. 126 (6): 742–761. doi:10.1016/j.pgeola.2015.08.010. ISSN 0016-7878.
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