Upward‐Doming Zones of Gas Hydrate and Free Gas at the Bases of Gas Chimneys, New Zealand's Hikurangi Margin

Focused gas migration through the hydrate stability zone in vertical conduits is a global phenomenon. The process can lead to concentrated formation and seafloor seepage, which influences biodiversity ocean biogeochemistry. However, much unknown about how co-exist within around conduits. We present seismic imaging of system beneath four-way closure anticlinal ridge at New Zealand's southern Hikurangi subduction margin. Gas has accumulated base thickness up ∼240 m, ultimately led hydraulic fracturing propagation conduit seafloor. Despite existence an array normal faults ridge, these structures are not exploited as long-range flow Directly conduit, extending upward from regional stability, broad characterized by both negative- positive-polarity reflections. interpret this volume sediment hosting free gas, that developed due partial trapping mass transport deposit. Similar highly reflective zones have been identified bases other conduits, but they intrinsic all systems. suggest pronounced intervening sealing units determine whether or form.