科研之友
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摘要
Ruapehu is an active similar to 150 km3 andesite-dacite composite volcano located at the southern end of the Taupo Volcanic Zone, New Zealand. The growth of the present-day edifice has occurred throughout coeval eruptive and glacial histories since similar to 200 ka. We present high-precision Ar-40/Ar-39 eruption ages for 46 samples and whole-rock major element geochemical data for 238 samples from lava flows. These new and existing data are interpreted in the context of geomorphologic and geologic mapping, volcano-ice interaction processes and glacier reconstructions to present an improved chronostratigraphic framework and new edifice evolution history for Ruapehu. Sub-glacial to ice-marginal effusive eruption of medium-IC basaltic-andesites and andesites constructed the northern portion of the exposed edifice between similar to 200 and 150 ka, and a wide southeast planeze as well as parts of the northern, eastern and western flanks between similar to 160 and 80 ka. None of the dated lava flows have ages in the range of 80-50 ka, which may reflect an eruptive hiatus. Alternatively the lack of ages may be the result of erosion and burial of lavas and syn-eruptive glacial conveyance of lava flows to the ring plain during.glacial advance at 70-601Our approach to integrating field and geochronological datasets from Ruapehu is directly relevant to the evolution of glaciated Quaternary composite cones worldwide, particularly those along the circum-Pacific continental volcanic arcs.
- 出版日期2016-11-15
