Geochemistry of Gases in the Alpine Fault, DFDP-2

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The Alpine Fault on the South Island of New Zealand is a major feature, showing a NE movement of 27 mm/yr and rapid uplift although no major earthquakes have occurred in historic time. In the context of the ICDP project DFDP-2 into the Alpine Fault, we propose to perform a systematic and comprehensive study on the composition of gases extracted on-line from drill mud and from down hole fluid samplers, which will be obtained during the drilling campaign in 2014.The proposed technique provides information on all free circulating fluids from the drilled rock, faults and alteration zones and allows, thus, to make a qualitative and semi-quantitative assessment of the volatile components along the drilled profile through the Alpine fault. In selected gas samples we will determine the abundances of major and trace gas components (CO2, N2, CH4, Ar, He etc.), the elemental and isotopic compositions of the noble gases (He, Ne, Ar, Kr, Xe) and 12C/13C in CO2 and CH4.Based on the chemical characterization of the individual fluid systems above and below the fault zone we hope to provide answers to the key question: Are there any systematic compositional differences in the gas composition of the Indo-Australian and Pacific plates along the Alpine fault, and does a hydraulic connection exist between the structural elements at depth and the hot springs at the surface?