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Ferruginous thermal spring complexes, northwest Tasmania: evidence that far-field stresses acting on a fracture mesh can open and maintain vertical fluid flow in carbonate terrains
journal contribution
posted on 2023-05-17, 09:31 authored by Davidson, GJ, Bavea, M, Harris, KFar-field stress changes in the southern Australian plate since 5 Ma have produced significant areas of uplift and seismicity. In northwest Tasmania, there is evidence that this stress reorientation to maximum horizontal NW–SE stress has influenced meteoricderived thermal (15–20°C) discharge patterns of confined karstic aquifers, by placing pre-existing NWtrending faults/fractures into a dilated state or a critically stressed state. Previous studies have shown that spring discharge has operated continuously for at least 65,000 years, and has transported large volumes of solutes to the surface to be deposited as mounds of calcite-goethite-silica up to 7 m high. The thermal spring chemistry at one site, Mella, is consistent with descent to at least 1.2–1.5 km, although the hinterland within 50 km is less than 500 m elevation. Thermal spring chemistry is consistent with most of the deep water–rock interaction occurring in low-strontium Smithton Dolomite. While some of this water is discharged at springs, some instead intersects shallow zones of NE-fracture-controlled rock (2×4 km in area) with karstic permeability where, although confined and subject to a NE-directed hydraulic gradient, it circulates and cools to ambient temperature, with only minor mixing with other groundwaters.
History
Publication title
Hydrogeology JournalVolume
19Issue
7Pagination
1367-1386ISSN
1431-2174Department/School
School of Natural SciencesPublisher
Springer-VerlagPlace of publication
175 Fifth Ave, New York, USA, Ny, 10010Rights statement
Copyright 2011 Springer-VerlagRepository Status
- Restricted