loading page

Near-ridge seamount volcanism in the easternmost segment of the Australian-Antarctic Ridge: Distribution, morphology, and magnetism
  • +1
  • Hakkyum Choi,
  • Seung-Sep Kim,
  • Sung-Hyun Park,
  • Hyoung Jun Kim
Hakkyum Choi
Korea Polar Research Institute

Corresponding Author:[email protected]

Author Profile
Seung-Sep Kim
Chungnam National University
Author Profile
Sung-Hyun Park
Korea Polar Research Institute
Author Profile
Hyoung Jun Kim
Korea Polar Research Institute
Author Profile

Abstract

The Australian-Antarctic Ridge (AAR) is the intermediate spreading system located between the Southeast Indian Ridge and Macquarie Triple Junction of the Australian-Antarctic-Pacific plates. KR1 is the easternmost and longest AAR segment and exhibits unique axial morphology and various volcanic structures. Within it, we identified three linearly aligned volcanic seamount chains positioned parallel to the seafloor spreading direction. We found that the seamount chains had formed asymmetrically and had developed through near-ridge volcanism at some distance away from the KR1 axis. Based on high-resolution bathymetric data, we identified the spatial distribution, morphology, and summit types of the isolated volcanic structures composing the seamount chains. The magnetic constraints on the age of the identified seamounts indicate that most had a formation time of less than ~600 kyrs, which primarily occurred during four distinct volcanic pulses from 0.3-0.8 Ma, 0.9-1.1 Ma, 1.6-2.1 Ma, and 2.2-2.7 Ma (or two major distinct pulses from 0.3-1.1 Ma and 1.6-2.7 Ma). When inconsistency existed between the observed and modeled ages of volcanic structures, volcanos were found to have a temporal gap of 200-650 kyrs between their formation and that of the underlying seafloor. Such volcanos are thought to have developed due to off-axis volcanism at a distance of 7-20 km. Considering the scale of off-axis volcanism and thickening lithosphere of such areas of ~20 km away from the axis of the intermediate spreading ridge, we propose that the seamounts originated from a deep plume source beneath the oceanic lithosphere.