Volcanism in the central Taupo Volcanic Zone, New Zealand: tempo, styles and controls
Published:January 01, 2009
C. J. N. Wilson, D. M. Gravley, G. S. Leonard, J. V. Rowland, 2009. "Volcanism in the central Taupo Volcanic Zone, New Zealand: tempo, styles and controls", Studies in Volcanology: The Legacy of George Walker, T. Thordarson, S. Self, G. Larsen, S. K. Rowland, Á. Höskuldsson
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The central Taupo Volcanic Zone (TVZ) in New Zealand currently is the most frequently active and productive area of silicic (overwhelmingly rhyolitic) volcanism on Earth. From 1.6 Ma to present, 25 caldera-forming eruptions have occurred, largely represented by ignim-brites, of which 23 are of dacitic to rhyolitic composition (c. 65-77% SiO2). These eruptions together represent c. 6000 km3 of magma, but this record is known to be incomplete. Other large (but as yet unquantified) eruptions are recorded in deep-sea cores and now-uplifted Pleistocene marine sediments, but correlations to mapped ignimbrite sheets are incomplete and volumes unknown. From 61 ka to present, a mostly complete sequence is known from exposed deposits and 68 eruptions, totalling 782 km3 of magma, are catalogued here. In this time period, three eruptions (1.8 ka, 35 km3; 26.5 ka, 530 km3; 61 ka, 80 km3) were rhyolitic caldera-forming events that represent 82% of the volume erupted. The remaining 65 eruptions (137 km3, magma) consist of three basaltic, eight dacitic to rhyodacitic and 54 rhyolitic (≥72% SiO2) events ranging in volume from <0.01 to 17.5 km3. Average central TVZ eruption rates from large caldera-forming events alone are 3.8km3kyr−1, while since 61 ka the rate is 12.8 km3 kyr−1. The former value is similar to those for intracontinental silicic volcanic provinces like Yellowstone (2.1 Ma to present, 3.0 km3 kyr−1) and the Southern Rocky Mountain volcanic field (29.4-26.9 Ma, 5km3kyr−1), where there is no clear record of smaller events. Magnitude-frequency relationships for large caldera-forming events in the central TVZ are broadly similar to those in the Southern Rocky Mountain volcanic field. However, the TVZ record since 61 ka shows magnitude-frequency relationships that imply an order-of-magnitude greater frequency in this latest period of activity for events of a given size up to >100 km3. TVZ eruptions are not evenly distributed in time, and clustering of events caused by interactions with tectonic processes are common.
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Studies in Volcanology: The Legacy of George Walker
Professor George Patrick Leonard Walker was one of the fathers of modern quantitative volcanology and arguably the foremost volcanologist of the twentieth century. In his long career, George studied a wide spectrum of volcanological problems and in doing so influenced almost every branch of the field. This volume, which honours his memory and his contributions to the field of volcanology, contains a collection of papers inspired by, and building upon, many of the ideas previously developed by George. Many of the contributors either directly studied under and worked with George, or were profoundly influenced by his ideas. The topics broadly fall under the three themes of lava flows and effusion, explosive volcanism, and volcanoes and their infrastructure.