Ferruginous thermal spring complexes, northwest Tasmania: evidence that far-field stresses acting on a fracture mesh can open and maintain vertical flow in carbonate terrains

Garry J. Davidson, Michael Bavea, Kathryn Harris

    Research output: Contribution to journalArticleResearchpeer-review

    1 Citation (Scopus)

    Abstract

    Far-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 meteoric-derived thermal (15-20°C) discharge patterns of confined karstic aquifers, by placing pre-existing NW-trending 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.

    Original languageEnglish
    Pages (from-to)1367-1386
    Number of pages20
    JournalHydrogeology Journal
    Volume19
    Issue number7
    DOIs
    Publication statusPublished - Nov 2011

    Fingerprint

    thermal spring
    stress field
    carbonate
    Australian plate
    confined aquifer
    water-rock interaction
    stress change
    strontium
    goethite
    seismicity
    dolomite
    solute
    calcite
    deep water
    silica
    uplift
    permeability
    hydraulics
    groundwater
    rock

    Cite this

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    title = "Ferruginous thermal spring complexes, northwest Tasmania: evidence that far-field stresses acting on a fracture mesh can open and maintain vertical flow in carbonate terrains",
    abstract = "Far-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 meteoric-derived thermal (15-20°C) discharge patterns of confined karstic aquifers, by placing pre-existing NW-trending 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.",
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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 flow in carbonate terrains. / Davidson, Garry J.; Bavea, Michael; Harris, Kathryn.

    In: Hydrogeology Journal, Vol. 19, No. 7, 11.2011, p. 1367-1386.

    Research output: Contribution to journalArticleResearchpeer-review

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