Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/616
AuthorsD'Antonio, M.* 
Kristensen, M. B.* 
TitleSerpentine and brucite of ultramafic clasts from the South Chamorro Seamount (Ocean Drilling Program Leg 195, Site 1200): inferences for the serpentinization of the Mariana forearc mantle
Issue DateDec-2004
Series/Report no.68(6)
DOI10.1180/0026461046860229
URIhttp://hdl.handle.net/2122/616
Keywordsserpentinization
mineral chemistry
serpentine mud volcano
Ocean Drilling Program
forearc mantle
Subject Classification04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology 
04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry 
AbstractSerpentine minerals and brucite in ultramafic rocks from the South Chamorro Seamount were characterized chemically to investigate the serpentinization of the Mariana forearc mantle. Relict primary minerals of the serpentinites are olivine, enstatite and minor Cr-spinel and diopside. The secondary minerals are mostly serpentine and brucite with minor magnetite. The serpentine minerals, mostly lizardite and chrysotile, display large compositional variations. Al2O3 and Cr2O3 contents depend generally upon the nature of the primary mineral from which the serpentine was derived. Both serpentine minerals and brucite exhibit wide Mg, Fe and Mn substitution: the Mg# ranges are 95.1 77.2 and 88.9 60.8, respectively. These mineralogical and chemical features allowed us to estimate an upper temperature limit for serpentinization of ~200 300ºC, in agreement with recent thermal models which suggest that the serpentinized mantle wedge of the Izu-Bonin-Mariana subduction zone is cold. The high degree of serpentinization (40 100%, average >75%), and the serpentine + brucite paragenesis of these ultramafics imply that the Mariana forearc mantle has a significantly reduced density and strength down to ~30 km, which provides a driving mechanism for serpentinite diapirism. Pervasive serpentinization of the forearc by fluids released from the de´collement zone also explains the low seismicity of the Izu-Bonin-Mariana subduction zone.
Appears in Collections:Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
DAntonio M.pdf5.53 MBAdobe PDFView/Open
mineralogical magazine.htmredirect - mineralogical magazine441 BHTMLView/Open
Show full item record

Page view(s)

75
Last Week
0
Last month
0
checked on Aug 22, 2017

Download(s)

44
checked on Aug 22, 2017

Google ScholarTM

Check

Altmetric