Expedition 366 methods

Fryer, Patricia; Wheat, C. G.; Williams, T.; Albers, Elmar; Bekins, Barbara A.; Debret, Baptiste; Deng, Jianghong; Dong, Yanhui; Eickenbusch, P.; Frery, Emanuelle; Ichiyama, Yuji; Johnson, K. T. M.; Johnston, R.M.; Kevorkian, R.T.; Kurz, Walter; Magalhães, Vítor; Mantovanelli, S.S.; Menapace, W.; Menzies, C.D.; Michibayashi, K.; Moyer, Craig L.; Mullane, K.K.; Park, J.-W.; Price, Roy E.; Ryan, Jeffrey G.; Shervais, John W.; Sissmann, Olivier; Suzuki, Shino; Takai, Ken; Walter, B.; Zhang, R.

doi:10.14379/iodp.proc.366.102.2018

Cited by 16 publications

(35 citation statements)

References 47 publications

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“…Together with mobilized serpentinite fault gouge these fluids rise through the mantle and crust of the Philippine Sea Plate to the seafloor, where they form more than a dozen active serpentinite mud volcanoes typically tens of kilometers in diameter and up to 2.5 km high (Fryer and Fryer, 1987;Fryer, , 1996. These structures are chiefly composed of unconsolidated serpentinite mudflows with clasts of serpentinized forearc mantle peridotite and other rare xenoliths including sediments and mafic rocks derived from the subducted Pacific Ocean crust (e.g., Maekawa et al, 1995;Fryer et al, 1999Fryer et al, , 2018b. The mud volcanoes are found at a range of distances from the trench.…”

Section: Study Area and Materialsmentioning

confidence: 99%

“…Pore waters were sampled from the serpentinite mud volcanoes during IODP Expedition 366 following onboard methods described in Fryer et al (2018a). Preparation for the analysis of Sr isotopes was undertaken in the University of Southampton's class 100 clean laboratories.…”

Section: Strontiummentioning

confidence: 99%

“…The compositions of these fluids reflect prograde metamorphic processes in the subducting lithosphere and hence provide a direct, natural window into an active subduction system (e.g., Fryer et al, 1985Fryer et al, , 1995Hulme et al, 2010). In particular fluids upwelling at the deeperrooted mud volcanoes exhibit high carbonate alkalinities 3 ) and elevated concentrations of dissolved hydrocarbons (CH 4 and C 2 H 6 ), indicative of decarbonation reactions in the downgoing plate at depths of < 30 km (Mottl et al, 2003;Hulme et al, 2010;Fryer et al, 2018b).…”

Section: Introductionmentioning

confidence: 99%

“…Here we have studied xenoliths brought to the seafloor along with fluids in the Mariana serpentinite mud volcanoes recovered during International Ocean Discovery Program (IODP) Expedition 366 (Fryer et al, 2018b). The samples investigated include metavolcanic and metasedimentary rocks as well as serpentinized peridotite.…”

Section: Introductionmentioning

confidence: 99%

“…Such carbonate formation below the "cold nose" of a convergent margin represents a sink for C in the deep carbon cycle that remains largely unquantified. Acrossforearc trends in upwelling fluid chemistry in the mud volcanoes (Fryer et al, 2018b) imply that decarbonation at depth may be widespread in the Mariana subduction system.…”

Section: Introductionmentioning

confidence: 99%

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Fluid–rock interactions in the shallow Mariana forearc: carbon cycling and redox conditions

et al. 2019

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Abstract. Few data exist that provide insight into processes affecting the long-term carbon cycle at shallow forearc depths. To better understand the mobilization of C in sediments and crust of the subducting slab, we investigated carbonate materials that originate from the subduction channel at the Mariana forearc (< 20 km) and were recovered during International Ocean Discovery Program Expedition 366. Calcium carbonates occur as vein precipitates within metavolcanic and metasedimentary clasts. The clasts represent portions of the subducting lithosphere, including ocean island basalt, that were altered at lower blueschist facies conditions and were subsequently transported to the forearc seafloor by serpentinite mud volcanism. Euhedral aragonite and calcite and the lack of deformation within the veins suggest carbonate formation in a stress-free environment after peak metamorphism affected their hosts. Intergrowth with barite and marked negative Ce anomalies in carbonate attest the precipitation within a generally oxic environment, that is an environment not controlled by serpentinization. Strontium and O isotopic compositions in carbonate (87Sr∕86Sr = 0.7052 to 0.7054, δ18OVSMOW = 20 to 24 ‰) imply precipitation from slab-derived fluids at temperatures between ∼130 and 300 ∘C. These temperature estimates are consistent with the presence of blueschist facies phases such as lawsonite coexisting with the carbonates in some veins. Incorporated C is inorganic (δ13CVPDB = −1 ‰ to +4 ‰) and likely derived from the decarbonation of calcareous sediment and/or oceanic crust. These findings provide evidence for the mobilization of C in the downgoing slab at depths of < 20 km. Our study shows for the first time in detail that a portion of this C forms carbonate precipitates in the subduction channel of an active convergent margin. This process may be an important asset in understanding the deep carbon cycle since it highlights that some C is lost from the subducting lithosphere before reaching greater depths.

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Section: Study Area and Materialsmentioning

confidence: 99%

Section: Strontiummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fluid–rock interactions in the shallow Mariana forearc: carbon cycling and redox conditions

et al. 2019

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Fluid‐Mantle Interaction Along the Mariana Convergent Margin

Miladinova,

Kurz,

Hilmbauer‐Hofmarcher

2023

Geochem Geophys Geosyst

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Active serpentinite mud volcanoes in the forearc region of the Izu‐Bonin‐Mariana system represent an excellent natural laboratory for studying the geochemical processes along convergent plate margins and the associated forearc. During IODP Expedition 366, serpentinite mud with lithic clasts from the underlying forearc crust and mantle as well as from the subducting Pacific Plate was recovered. Ultramafic clasts from Fantangisña Seamount reveal very high degrees of serpentinization with mesh and bastite textures as well as development of late lizardite and chrysotile veins, which suggests serpentinization temperatures below 200°C. On the other hand, recovered harzburgites and, on occasion, dunites from Asùt Tesoru Seamount show a well‐preserved primary assemblage with low degrees of serpentinization and forearc peridotite characteristics. Fine‐grained antigorite associating with lizardite has been identified throughout the serpentine mud matrix, suggesting an alteration temperature of c. 340°C. Furthermore, alteration conditions during rodingitization point to temperatures of at least 228°C, estimated via chlorite geothermometry. Additionally, a rare ophicarbonate clast containing andraditic as well as Cr‐rich hydrogarnets from Asút Tesoru Seamount indicates crystallization temperatures of at least 230°C. Hence, a trend of lower temperature of serpentinization and higher degree of alteration closer to the trench. The detailed characterization of the fluid‐rock alteration conditions as well as fluids composition and transport permits a better constraining of the fluid–rock interactions and related mass transfers within subduction zones and during ascent of serpentinite fault gouge within mud volcano conduits and in mudflows after their emplacement on the flanks of the edifices.

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