The Middle to Late Devonian Eden-Comerong-Yalwal Volcanic Zone of Southeastern Australia

an ancient analogue of the Yellowstone-Snake River Plain region of the USA

K. A. Dadd*

*Corresponding author for this work

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    The Middle to Late Devonian Yalwal Volcanics, Comerong Volcanics, Boyd Volcanic Complex and associated gabbroic and A-type granitic plutons form part of a continental volcano-tectonic belt, the Eden-Comerong-Yalwal Volcanic Zone (EVZ), located parallel to the coast of southeastern Australia. The EVZ is characterised by an elongate outcrop pattern, bimodal basalt-rhyolite volcanism, and a paucity of sedimentary rocks. Volcanic centres were located along the length of the volcanic zone at positions indicated by subvolcanic plutons, dykes, rhyolite lavas and other proximal vent indicators including surge bedforms in tuff rings, and hydrothermal alteration. Previous interpretations that suggested the volcanic zone was a fault bounded rift are rejected in favour of a volcano-tectonic belt. The Yellowstone-Snake River Plain region (Y-SRP) in the USA is an appropriate analogue. Both regions have basalt lavas which range in composition from olivine tholeiite to ferrobasalt, alkalic rhyolitic rocks enriched in Y, Zr and Th, large rhyolite lava flows, plains-type basalt lava flows, and a paucity of sedimentary rocks. The Y-SRP is inferred to have developed by migration of the American plate over a fixed hot spot leading to a northeast temporal progression of the focus of volcanic activity. Application of a similar hot spot model to the EVZ (using a length of 300 km and a time range for volcanic activity of 5-10 Ma), suggests that during the Middle to Late Devonian the Australian plate was moving at a rate of between 3 and 6 cm/yr relative to the hot spot and that the northern extent of the volcanic zone at any time was a topographically high region with rhyolitic activity, similar to present day Yellowstone. As the focus of activity moved northward, the high region subsided and the depression was flooded by basalt. The EVZ was much wider (up to 70 km) and much longer than the belt defined by present-day outcrop and was of comparable scale to the Y-SRP. The main difference between the two volcanic belts is the lack of large pyroclastic flows and identifiable caldera complexes in the EVZ.

    Original languageEnglish
    Pages (from-to)277-291
    Number of pages15
    JournalTectonophysics
    Volume214
    Issue number1-4
    DOIs
    Publication statusPublished - 30 Nov 1992

    Fingerprint Dive into the research topics of 'The Middle to Late Devonian Eden-Comerong-Yalwal Volcanic Zone of Southeastern Australia: an ancient analogue of the Yellowstone-Snake River Plain region of the USA'. Together they form a unique fingerprint.

    Cite this