Hydrothermal activity revealed by rock magnetic anomaly from core sediments in the southern Okinawa Trough

Huang, Yushu; Su, Chih-Chieh; Doo, Wen Bin; Hsu, Shu Kun; Tsai, Chia-Wei; Wang, Hsueh Fen; Lin, Shih Chang; Liang, Chin Wei; Lin, Jing Yi; Chen, Jui E.; Lin, Yi Jung; Wang, Yunshuen

doi:10.3319/tao.2019.07.31.01

Cited by 5 publications

(2 citation statements)

References 24 publications

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“…Based on the above observations, the sediments of the MHV hydrothermal eld are rich in methane uids, leading to low magnetic susceptibility. This explanation also supports the hypothesized relationship between hydrothermal activity and magnetic anomalies reported by Huang et al (2019).…”

Section: Sediment Description and Propertiessupporting

confidence: 90%

Hydrothermal characteristics of the Mienhua submarine volcano in the southernmost Okinawa trough

Chen

Hsu

et al. 2023

Mar Geophys Res

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The Mienhua submarine volcano (MHV) is located in the southernmost Okinawa Trough and exhibits vigorous hydrothermal activity. This paper presents a detailed volcanic morphological analysis of the MHV, which has not been fully explored or discussed in terms of its hydrothermal characteristics and their relationship to hydrothermal activities.The MHV is situated at a water depth of 1,370 m and has a width of 2.2 km and relief height of 220 m. The MHV is an asymmetric volcano composed of two summits in the center, rugged mounds in the west, and at regions in the east. Two hydrothermal vents, Devil Chimney and Witch Mound were discovered through acoustic ares and a high backscatter intensity in the eastern ank. Based on three repeated mappings, no noticeable depth changes were observed at the acoustic are zone compared to the area of the rugged mounds and two summits. In addition, a sediment core collected in a high backscatter intensity patch displayed low magnetic susceptibility, which could be in uenced by the high methane levels in hydrothermal uid that ows through sediments. An acoustically transparent zone adjoining active ares was observed in the sub-bottom pro les in the southeastern ank of the MHV, suggesting that the morphological and volcanic features are mainly concentrated in the southeast. Based on the seabed characteristics and the distribution of sills and re ectors in the multichannel seismic pro les, we inferred that the MHV is an off-axis vent that has experienced at least two stages of morphological development.

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Section: Sediment Description and Propertiessupporting

confidence: 90%

Hydrothermal characteristics of the Mienhua submarine volcano in the southernmost Okinawa trough

Chen

Hsu

et al. 2023

Mar Geophys Res

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“…An apparent acoustically transparent zone was imaged in the shallow sediments of the two sites (Hsu, 2017), suggesting a very active fluid/gas circulation system (Hsu, 2017; Hsu et al., 2019). In addition, the low magnetic anomalous behavior of the two sites also suggests a high hydrothermal potential due to hydrothermal alteration and metasomatism (Doo et al., 2019; Huang et al., 2019).…”

Section: Geological Backgroundmentioning

confidence: 99%

Gas Emission Characteristics and Tectonic Implications in the Southernmost Okinawa Trough From Split‐Beam Echo Sounder Observations

Lin,

Hsu

et al. 2024

JGR Oceans

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Traditionally, single‐beam echo sounder (SBES) data are used to determine the position of emission structures in the form of a two‐dimensional profile, which may not be straightforward enough to correlate the data of adjacent profiles and determine the exact discharge area. In this study, we develop semiautomatic software to remove noise and select possible flare signals to enhance the speed and precision of the data processing. The program also allows for the transformation of the data into a three‐dimensional point cloud distribution by computing the receiving angle of the data. By applying this method to investigate the distribution and mechanism of gas emission structures in the South Okinawa Trough (SOT), we determine four high flux areas and 22 isolated plumes with roots. Widespread gas flares usually occur in areas with large‐scale volcanic activity or gas‐enriched structures. Isolated gas plumes could be found for a single knoll outcrop and normal faulting structures. The energy of the flares around the knoll area is generally stronger than that observed along the normal faults. Compared with other geophysical data, we find that the widespread distribution of gas flares generally implies a larger hydrothermal potential, which may not be revealed by single‐profile acoustic image observations. We also find that the direction of flares is strongly influenced by tides, and the height of the flare represents the thermocline as a strong boundary for bubbles composited by carbon dioxide.

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Shallow gas hydrates off southwest Taiwan and their mechanisms

Huang

Hsu

et al. 2021

Mar Geophys Res

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We have collected two shallow gas hydrate samples at two sites having different geological settings off southwest Taiwan during the cruise MD214 in 2018. The first core site, MD18-3542, is on the South Yuan-An East Ridge at ~ 1200 m water deep, where a structural unconformity covered by fine-silt sediments appears at ~ 5.5 m below the seafloor. The second core site, MD18-3543, is close to the Good-Weather Ridge at ~ 1100 m water deep, where a gas-related pockmark structure and authigenic carbonates are present at shallow strata with fine-silt sediments near the seafloor. Sediment properties of core MD18-3542 are distinctively different above and below the layer corresponding to the unconformity. Both cores show obvious gaps or voids in the lower core halves. The core features could be linked to the dissociated methane upward migrating from deep strata. Core site settings with upwelling methane would favor the formation of shallow gas hydrates. At site MD18-3542, the shallow hydrate could be formed due to high concentration methane kept beneath the unconformity covered by fine-silt sediments. At site MD18-3543, the shallow hydrate could be formed due to an extremely high flux of upwelling methane trapped either beneath the authigenic carbonates or fine-silt sediments.

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Hydrothermal activity revealed by rock magnetic anomaly from core sediments in the southern Okinawa Trough

Cited by 5 publications

References 24 publications

Hydrothermal characteristics of the Mienhua submarine volcano in the southernmost Okinawa trough

Hydrothermal characteristics of the Mienhua submarine volcano in the southernmost Okinawa trough

Gas Emission Characteristics and Tectonic Implications in the Southernmost Okinawa Trough From Split‐Beam Echo Sounder Observations

Shallow gas hydrates off southwest Taiwan and their mechanisms

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