• Media type: E-Article
  • Title: Magmatism, serpentinization and life: Insights through drilling the Atlantis Massif (IODP Expedition 357)
  • Contributor: Früh-Green, Gretchen L. [Author]; Orcutt, Beth N. [Author]; Rouméjon, Stéphane [Author]; Lilley, Marvin D. [Author]; Morono, Yuki [Author]; Cotterill, Carol [Author]; Green, Sophie [Author]; Escartin, Javier [Author]; John, Barbara E. [Author]; McCaig, Andrew M. [Author]; Cannat, Mathilde [Author]; Ménez, Bénédicte [Author]; Schwarzenbach, Esther M. [Author]; Williams, Morgan J. [Author]; Morgan, Sally [Author]; Lang, Susan Q. [Author]; Schrenk, Matthew O. [Author]; Brazelton, William J. [Author]; Akizawa, Norikatsu [Author]; Boschi, Chiara [Author]; Dunkel, Kristina G. [Author]; Quéméneur, Marianne [Author]; Whattam, Scott A. [Author]; Mayhew, Lisa [Author]; [...]
  • Published: Elsevier, 2018-12-15
  • Language: English
  • DOI: https://doi.org/10.1016/j.lithos.2018.09.012
  • Origination:
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  • Description: Highlights • Seabed rock drills and real-time fluid monitoring for first time in ocean drilling • First time recovery of continuous sequences along oceanic detachment fault zone • Highly heterogeneous rock type and alteration in shallow detachment fault zone • High methane and hydrogen concentrations in Atlantis Massif shallow basement • Oceanic serpentinites potentially provide important niches for microbial life Abstract IODP Expedition 357 used two seabed drills to core 17 shallow holes at 9 sites across Atlantis Massif ocean core complex (Mid-Atlantic Ridge 30°N). The goals of this expedition were to investigate serpentinization processes and microbial activity in the shallow subsurface of highly altered ultramafic and mafic sequences that have been uplifted to the seafloor along a major detachment fault zone. More than 57 m of core were recovered, with borehole penetration ranging from 1.3 to 16.4 meters below seafloor, and core recovery as high as 75% of total penetration in one borehole. The cores show highly heterogeneous rock types and alteration associated with changes in bulk rock chemistry that reflect multiple phases of magmatism, fluid-rock interaction and mass transfer within the detachment fault zone. Recovered ultramafic rocks are dominated by pervasively serpentinized harzburgite with intervals of serpentinized dunite and minor pyroxenite veins; gabbroic rocks occur as melt impregnations and veins. Dolerite intrusions and basaltic rocks represent the latest magmatic activity. The proportion of mafic rocks is volumetrically less than the amount of mafic rocks recovered previously by drilling the central dome of Atlantis Massif at IODP Site U1309. This suggests a different mode of melt accumulation in the mantle peridotites at the ridge-transform intersection and/or a tectonic transposition of rock types within a complex detachment fault zone. The cores revealed a high degree of serpentinization and metasomatic alteration dominated by talc-amphibole-chlorite overprinting. Metasomatism is most ...
  • Access State: Open Access