Stratigraphy of the Lamington Volcanics in far Northeastern New South Wales |
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| Authors: | M B Duggan D R Mason |
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| Institution: | 1. Dept of Geology , University of Otago , Dunedin, New Zealand;2. Dept of Geology , University of Toronto , Toronto, Ontario, Canada , M5S 1A1 |
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| Abstract: | The stratigraphic nomenclature for the Lamington Volcanics in the southern part of the Tweed Shield Volcano is revised. An alkaline formation (the Kyogle Basalt) containing discontinuous rhyolitic‐agglomerate (the Homeleigh Agglomerate Member) and rhyolite flow (the Georgica Rhyolite Member) horizons is the basal unit of the volcanic succession. The Kyogle Basalt thins eastward where it is overlain by a subalkaline sequence comprising the Lismore Basalt, Nimbin Rhyolite, and Blue Knob Basalt respectively. The Lismore Basalt is composed predominantly of tholeiitic andesite with minor icelandite and sporadic flows of mildly alkaline rocks; tholeiitic andesites predominate in the Blue Knob Basalt. The Nimbin Rhyolite consists of rhyolite flows, and a relatively minor pyroclastic component (principally lapilli tuff). |
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