Magnetic Constraints on Off‐Axis Seamount Volcanism in the Easternmost Segment of the Australian‐Antarctic Ridge

Choi, Hakkyum; Kim, Seung‐Sep; Park, Sung Hyun

doi:10.1029/2020gc009576

Cited by 5 publications

(7 citation statements)

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“…The compositional heterogeneity in the upper mantle can facilitate melt buoyancy and a small-scale upwelling at a considerable distance from the ridge axis [7,[9][10][11][12]. Our previous study on marine magnetic data acquired from the seamount chains of KR1 [16] estimated that the volcanic edifices comprising the seamount chains were largely a result of the off-axis volcanic eruptions located approximately 10-20 km from the ridge axis.…”

Section: Discussionmentioning

confidence: 99%

“…The axial morphology of KR1 can be divided into the eastern section featuring the axial valley, the central section with the axial high, and the western section with numerous seamounts, and the axial plateau (Figure 1b,c) [16,24,27,28]. According to the division by axial morphology, excessive magma supply in the western section of KR1 is expected to be much higher than that in the eastern section.…”

Section: Discussionmentioning

confidence: 99%

“…Based on the shipboard magnetic data, the full spreading rates of KR1 were determined as 60-67 mm/year [13,16]. The classification scheme for global ridge systems defines an intermediate-spreading ridge as a full-spreading ridge at 50-80 mm/year [17,18].…”

Section: Introductionmentioning

confidence: 99%

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Geomorphological and Spatial Characteristics of Underwater Volcanoes in the Easternmost Australian-Antarctic Ridge

et al. 2021

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Underwater volcanoes and their linear distribution on the flanks of mid-ocean ridges are common submarine topographic structures at intermediate- and fast-spreading systems, where sufficient melt supplies are often available. Such magma sources beneath the seafloor located within a few kilometers of the corresponding ridge-axis tend to concentrate toward the axis during the upwelling process and contribute to seafloor formation. As a result, seamounts on the flanks of the ridge axis are formed at a distance from the spreading axis and distributed asymmetrically about the axis. In this study, we examined three linearly aligned seamount chains on the flanks of the KR1 ridge, which is the easternmost and longest Australian-Antarctic Ridge (AAR) segment. The AAR is an intermediate-spreading rate system located between the Southeast Indian Ridge and Macquarie Triple Junction of the Australian-Antarctic-Pacific plates. By inspecting the high-resolution shipboard multi-beam bathymetric data newly acquired in the study area, we detected 20 individual seamounts. The volcanic lineament runs parallel to the spreading direction of the KR1 segment. The geomorphologic parameters of height, basal area, volume, and summit types of the identified seamounts were individually measured. We also investigated the spatial distribution of the seamounts along the KR1 segment, which exhibits large variations in axial morphology with depth along the ridge axis. Based on the geomorphology and spatial distribution, all the KR1 seamounts can be divided into two groups: the subset seamounts of volcanic chains distributed along the KR1 segment characterized by high elevation and large volume, and the small seamounts distributed mostly on the western KR1. The differences in the volumetric magnitude of volcanic eruptions on the seafloor and the distance from the given axis between these two groups indicate the presence of magma sources with different origins.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Geomorphological and Spatial Characteristics of Underwater Volcanoes in the Easternmost Australian-Antarctic Ridge

et al. 2021

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“…These strips are formed by the semi‐continuous formation of fresh oceanic crusts at the mid‐ocean ridge sites and the subsequent spreading to both sides; thus, the oceanic crust can record geomagnetic field information in situ, particularly the polarity reversals of the geomagnetic field (Vine, 1966; Vine & Matthews, 1963), which contributes to the establishment of the geomagnetic polarity time scale (GPTS) (Cande & Kent, 1995; Gee & Kent, 2007). Subsequently, marine magnetic anomalies have been widely used in a range of research fields, such as the evolution of oceanic basin (Kamesh Raju et al, 2004; Tikku & Cande, 1999), reconstruction of oceanic crust subduction and mid‐ocean ridge accretion process (Dumais et al, 2021; Li & Wei, 2016; Michaud et al, 2006; Parnell‐Turner et al, 2016), formation mechanism of oceanic microplates (Sleeper & Martinez, 2016), dynamics of the triple junctions (Desa et al, 2019), spatial volume and formation period of seamounts (Choi et al, 2021), generation mechanism of short‐wavelength magnetic anomalies (Li et al, 2019), evolution of the geomagnetic field (Li et al, 2018), and exploration of hydrothermal vents (Zhang et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Influence of the oceanic crust structure on marine magnetic anomalies: Review and forward modelling

Zhang

Jiang

et al. 2022

Geological Journal

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Handling Editor: CHANDRAKALA. KOTESWARA Marine magnetic anomaly strips are important for plate tectonic studies, thereby promoting the development of the geoscience revolution. Most previous studies typically consider a lava layer with vertical polarity boundaries as a simplified magnetic source layer. However, it cannot accurately explain the observed magnetic anomaly data; thus, complex oceanic crusts with multiple magnetic source layers, such as lava, dike, and gabbro layers, and various polarity boundary dip angles should be considered. To date, there is a lack of systematic understanding about how the dike and gabbro layers affect the total marine magnetic anomalies, particularly the effect of lava layers with different boundary inclinations on the intensity and polarity boundary of the magnetic anomaly. This study aimed to confirm the significance of these factors. Hence, we systematically simulated and analysed the magnetic anomaly characteristics with different inclination and magnetization settings for each layer using the forward modelling method and determined the impact of the complexity of the magnetic structure of the oceanic crust on the magnetic anomaly. Our results showed that the contributions of the dike and gabbro layers to the magnetic anomalies was up to 10%-30% and cannot be ignored. Moreover, the polarity transition point may shift with the inclination of the lava, dike, and gabbro layers but is insensitive to the magnetization of each layer. This study emphasizes the significance of the dike and gabbro layers and the inclination variations of different layers, which should be thoroughly studied. This study facilitates a reasonable interpretation of the magnetic structure of the oceanic crust and further refines the boundary of the magnetization zone with alternative polarity.

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“…Since in situ samples of fresh basaltic rocks from volcanic constructs on the seafloor are difficult to obtain and their geochemical characteristics (i.e., low potassium contents) render them difficult to date by routine dating techniques, only a handful of seamounts have been radiometrically dated (Briais et al, 2009;Clouard & Bonneville, 2005;Koppers et al, 2004Koppers et al, , 2012. In order to overcome this problem, indirect estimates of seamount age have been obtained by modeling the flexural response of the lithospheric plate to a volcanic load or by analyzing magnetic anomaly profiles (Choi et al, 2021;Hwang & Kim, 2016;Watts et al, 1988Watts et al, , 2006. Here, we use an alternative approach, based on the thickness of sediment accumulated on top of newly formed seamounts, which is a novel proxy for the relative timing of seamount construction along linear chains located on the flanks of a MOR.…”

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Relative Timing of Off‐Axis Volcanism From Sediment Thickness Estimates on the 8°20’N Seamount Chain, East Pacific Rise

Fabbrizzi

Parnell‐Turner

Gregg

et al. 2022

Geochem Geophys Geosyst

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Volcanic seamount chains on the flanks of mid‐ocean ridges record variability in magmatic processes associated with mantle melting over several millions of years. However, the relative timing of magmatism on individual seamounts along a chain can be difficult to estimate without in situ sampling and is further hampered by Ar40/Ar39 dating limitations. The 8°20’N seamount chain extends ∼170 km west from the fast‐spreading East Pacific Rise (EPR), north of and parallel to the western Siqueiros fracture zone. Here, we use multibeam bathymetric data to investigate relationships between abyssal hill formation and seamount volcanism, transform fault slip, and tectonic rotation. Near‐bottom compressed high‐intensity radiated pulse, bathymetric, and sidescan sonar data collected with the autonomous underwater vehicle Sentry are used to test the hypothesis that seamount volcanism is age‐progressive along the seamount chain. Although sediment on seamount flanks is likely to be reworked by gravitational mass‐wasting and current activity, bathymetric relief and Sentry vehicle heading analysis suggest that sedimentary accumulations on seamount summits are likely to be relatively pristine. Sediment thickness on the seamounts' summits does not increase linearly with nominal crustal age, as would be predicted if seamounts were constructed proximal to the EPR axis and then aged as the lithosphere cooled and subsided away from the ridge. The thickest sediments are found at the center of the chain, implying the most ancient volcanism there, rather than on seamounts furthest from the EPR. The nonlinear sediment thickness along the 8°20’N seamounts suggests that volcanism can persist off‐axis for several million years.

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Magnetic Constraints on Off‐Axis Seamount Volcanism in the Easternmost Segment of the Australian‐Antarctic Ridge

Abstract: Seamounts offer key information to understand various tectonic and volcanic processes occurring in the Earth's lithosphere and the mantle domain beneath (

Cited by 5 publications

References 76 publications

Geomorphological and Spatial Characteristics of Underwater Volcanoes in the Easternmost Australian-Antarctic Ridge

Geomorphological and Spatial Characteristics of Underwater Volcanoes in the Easternmost Australian-Antarctic Ridge

Influence of the oceanic crust structure on marine magnetic anomalies: Review and forward modelling

Relative Timing of Off‐Axis Volcanism From Sediment Thickness Estimates on the 8°20’N Seamount Chain, East Pacific Rise

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