New England sapphire fields
One of Australia's most important sapphire-producing areas, in the basalt country of northern New South Wales around Inverell and Glen Innes. The sapphires grew deep in the crust during the alkali-basalt volcanism of the Central Volcanic Province, between about 38 and 19 million years ago, were carried up by the lavas, and were concentrated by rivers, first in old channels now buried (deep leads) and later in young alluvium.
Dated events and their evidence
- about 38,000,000 years ago mainstream
alkali-basalt volcanism of the Central Volcanic Province is under way; potassium-argon ages of its basalts span about 38 to 19 million years, and its centre steps westwards over time, from Glen Innes, Ben Lomond and Guyra towards Inverell and Armidale source - about 35,900,000 years ago mainstream
zircon inclusions in two sapphires from the province give uranium-lead ages of 35.9 ± 1.9 and 33.7 ± 2.1 million years, inside the age span of the basalts: the sapphires grew during the basalt magmatism source - about 34,000,000 years ago mainstream
in the Eocene and Oligocene, rivers concentrate sapphire in channels that are later buried, the deep-lead deposits of the central belt; the year marks the epochs, not a measured date source - 9,700 BCE mainstream
in the Holocene, streams of the eastern division rework sapphire into young alluvial deposits source
Where
29.7667° S, 151.1167° E
The point is Wikipedia's position for Inverell. The fields spread across the Central Volcanic Province, from west of Inverell and Armidale to the Glen Innes, Ben Lomond and Guyra area in the east.
Sources
- https://doi.org/10.5962/p.361301
- https://en.wikipedia.org/wiki/Inverell
- https://ozgeology.com/blogs/news/one-of-the-worlds-largest-sapphire-fields
Each event carries Aion's own evidence grade (mainstream, disputed or speculative). This page repeats what the globe shows for this place.