Extrusion dynamics of deepwater volcanoes revealed by 3-D seismic data
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Published:2019-08-02
Issue:4
Volume:10
Page:1269-1282
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ISSN:1869-9529
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Container-title:Solid Earth
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language:en
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Short-container-title:Solid Earth
Author:
Sun QiliangORCID, Jackson Christopher A.-L.ORCID, Magee CraigORCID, Mitchell Samuel J., Xie Xinong
Abstract
Abstract. Submarine volcanism accounts for ca. 75 % of the Earth's volcanic activity.
Yet difficulties with imaging their exteriors and interiors mean that the
extrusion dynamics and erupted volumes of deepwater volcanoes remain poorly
understood. Here, we use high-resolution 3-D seismic reflection data to
examine the external and internal geometry and extrusion dynamics of two
late Miocene–Quaternary deepwater (> 2 km emplacement depth)
volcanoes buried beneath 55–330 m of sedimentary strata in the South China
Sea. The volcanoes have crater-like bases, which truncate underlying strata
and suggest extrusion was initially explosive, and erupted lava flows that
feed lobate lava fans. The lava flows are > 9 km long and contain
lava tubes that have rugged basal contacts defined by ∼90±23 m high erosional ramps. We suggest the lava flows eroded down
into and were emplaced within wet, unconsolidated, near-seafloor sediments.
Extrusion dynamics were likely controlled by low magma viscosities as a
result of increased dissolved H2O due to high hydrostatic pressure and
soft, near-seabed sediments, which are collectively characteristic of
deepwater environments. We calculate that long-runout lava flows account
for 50 %–97 % of the total erupted volume, with a surprisingly minor
component (∼3 %–50 %) being preserved in the main volcanic
edifice. Accurate estimates of erupted volumes therefore require knowledge
of volcano and lava basal surface morphology. We conclude that 3-D seismic
reflection data are a powerful tool for constraining the geometry, volumes,
and extrusion dynamics of ancient or active deepwater volcanoes and lava
flows.
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Earth-Surface Processes,Geochemistry and Petrology,Geology,Geophysics,Soil Science
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