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Toward understanding the geohazards of Huangzuei volcano (Taiwan) from geomorphological mapping, 40Ar-39Ar dating and geochemical constraints

Wei-Che Li1,2、Kerry Sieh1,2、Yu Wang1 、Brian Jicha3、Yu-Chang Chan2

  • Affiliations:  1Department of Geosciences, National Taiwan University; 2Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan; 3Department of Geoscience, University of Wisconsin-Madison   

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 139

  • Lightning talk:

  • Programme No: 3.4.22

  • Theme 3 > Session 4

Abstract

Although it abuts the northern flank of the Taipei metropolitan area, hazards posed by the 25-km wide Tatun Volcanic Group (TVG) are poorly understood. The Huangzuei complex is one of the younger TVG volcanoes, with well-preserved landforms that comprise three sequences of andesitic flows that radiate northwestward, northeastward and eastward up to six km from a complex horseshoe-shaped, cratered 250-m tall edifice, Mt. Huangzuei. Very high-resolution topography from a LiDAR-based DEM enabled detailed demarcation and characterization of individual flows, including their volumes, thicknesses, and profiles. In our first year of work, we began to constrain the evolution of the volcano via 40Ar-39Ar dating and petrologic and geochemical analysis of a dozen samples from key lava flows. The northwestern flow sequence is composed of two flows. Two 40Ar-39Ar dates indicate that eruptions occurred 116.6±2.0 and 128.8±1.8 ka (2s). The as yet undated northeastern flow sequence comprises three distinct flows with pronounced ogives, one atop the other. The eastern flow sequence extends 3 km east and then 3 km north from Mt Huangzuei's summit. It includes five distinct flows and associated levees. The second oldest flow erupted 85.4±2.3 ka.  Our initial mapping and dating suggest that the Huangzuei complex has experienced at least three and possibly four eruptive episodes. Two of them are well constrained by petrological and geochemical analyses. We anticipate that samples yet to be collected this year will further constrain the eruptive history of Huangzuei volcano, toward the goal of quantifying its future geohazards.