Towards an improved understanding of local and distal volcanic stratigraphy in Auckland : stratigraphy of a long core from Glover Park (St Helier's Volcano) in Auckland

Hoverd, J.L.; Shane, P.A.; Smith, I.E.M.; Smith, V.C.; Wilson, C.J.N. 2005 Towards an improved understanding of local and distal volcanic stratigraphy in Auckland : stratigraphy of a long core from Glover Park (St Helier's Volcano) in Auckland . Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 2005/31 47 p.

Abstract: This report presents the initial findings from drilling and analysis of a 27.0 m core recovered from Glover Park (St Heliers volcano) in St Heliers, Auckland. This drill hole reached what is assumed to be the floor of the original explosion crater that formed during the eruption of St Heliers volcano. Recovery of core was complete, or near complete throughout the entire core. Logging and geochemical analysis has enabled identification of the source for macroscopic ash layers, including seven rhyolitic tephra layers from the central Taupo Volcanic Zone (mostly from Okataina and Taupo volcanic centres), 14 locally-derived basaltic tephras, and 10 tephras of andesitic-trachytic composition, most likely derived from Mt Taranaki. A further four samples lacked sufficient glass material to confidently assign a source. An additional local basaltic tephra is identified, based on physical appearance, which rendered geochemical analysis unnecessary. (auth)