Dataset Information

Kawamoto, Tatsuhiko; ORCID: 0000-0002-6989-874X
Yamamoto, Chihaya
Kugimiya, Kento
Ishido, Shinya
Ichiyama, Yuji; ORCID: 0000-0001-9156-9259
Fryer, Patricia; ORCID: 0000-0003-4264-1036

Serpentinite mud volcanoes form seamounts in the Mariana forearc region. The erupted muds undergo little compositional modification during ascent to the seafloor because the Mariana subduction zone lacks an accretionary prism. Raman spectroscopy confirms aqueous fluid inclusions in calcite crystals in tiny clasts recovered from drilled cores of Fantangisna and Asut Tesoru Seamounts (IODP Exp. 366) and South Chamorro Seamount (ODP Leg 195). The salinity and homogenization temperature of the fluid inclusions increase with the distance from the trench. The homogenization temperatures and salinity allow us to calculate isochoric pressure-temperature paths of the fluid inclusions. Estimated temperatures at the plate boundary increase from 355C at 14 km beneath Fantangisna to 450C and 475C at 18 km beneath Asut Tesoru and South Chamorro, respectively. These temperatures exceed estimates based on pore-fluid chemistry by approximately 200C and are 30-65C higher than temperatures derived from serpentine-magnetite oxygen isotope equilibria and chlorite geothermometry data. In contrast, they are lower than the estimated metamorphic temperatures inferred for mafic clasts (up to 590C at 50 km). The estimated plate-boundary temperatures represent the upper limits beneath each mud volcano. If calcite crystallized under the temperature range of mineral geothermometers, it crystallized in the mantle wedge. Metamorphic clasts that record higher-temperature signatures were likely transported from deeper in the subduction channel, or formed during the hotter conditions of subduction initiation, as previously suggested.

Kawamoto, T., Yamamoto, C., Kugimiya, K., Ishido, S., Ichiyama, Y., Fryer, P., 2026. Microthermometry data of fluid inclusion from the Mariana forearc serpentinite mud volcanoes, Version 1.0. Interdisciplinary Earth Data Alliance (IEDA). https://doi.org/10.60520/IEDA/114632. Accessed 2026-09-28.

2026-09-25

Creative Commons Attribution 4.0 International [CC-BY-4.0]

Coverage Scope: Regional (Continents, Oceans)
Geographic Location: Mariana forearc, western Pacific

Serpentinite mud volcanoes; saline fluid inclusions; homogenization temperature; subduction channel; Mariana trench

North: 18.1     South: 13.8     East: 147.2     West: 146

2026-09-26

Dataset