Detailed Morphology and Structure of an Active Submarine Arc Caldera: Brothers Volcano, Kermadec Arc

• DOI: 10.2113/econgeo.107.8.1557
• Publication Date: 2012-11-23T15:07:51Z
• Authors: R. W. Embley; C. E. J. de Ronde; S. G. Merle; B. Davy; F. C. Tontini
• Keywords: Caldera; Island arc; Volcanic cone; Submarine volcano

A survey of the Brothers caldera volcano (Kermadec arc) with autonomous underwater vehicle ABE has revealed new details morphology and structure this submarine frontal arc geologic setting its hydrothermal activity. formed between major SW-NEtrending faults within extensional field Havre Trough. may be unique among known calderas in that it four active systems, two high-temperature sulfide-depositing sites associated faulting on northwestern western walls (i.e., NW W sites, respectively), gas-rich summits constructional cones fill most southern part Upper Lower cone sites). The 3.0- × 3.4-km is well defined by a topographic rim encompassing ~320° circumference which lies bounds outer half-grabenshaped northwest southeast sectors. There not morphologically continuous ring fault (at map resolution), although near-vertical scarps are present discontinuously at base sections wall. width wall varies from <200 m southwest portion to ~750 northern section. widest sector, also largest documented area alteration where sea-floor magnetization lowest. In addition primary northwest-southeast elongation southwest-northeast structures caused regional back-arc strain field, there less developed west-southwestnorth-northeast intersecting appar- ent bathymetry outcrop scale submersible observations. Asymmetrical trap-doorstyle collapse considered possible mechanism for formation caldera.