Silica-rich lavas in the oceanic crust: experimental evidence for fractional crystallization under low water activity

We experimentally investigated phase relations and phase compositions as well as the influence of water activity ( a H 2 O) and redox conditions on the equilibrium crystallization path within an oceanic dacitic potassium-depleted system at shallow pressure (200 MPa). Moreover, we measured the partit...

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Bibliographic Details
Published in:Contributions to mineralogy and petrology 2016-10, Vol.171 (10), p.1, Article 83
Main Authors: Erdmann, Martin, Koepke, Jürgen
Format: Article
Language:English
Subjects:
Chlorine
Crystallization
Earth and Environmental Science
Earth Sciences
Fractionation
Geology
Marine environment
Mass spectrometry
Meltwater
Mineral Resources
Mineralogy
Oceanic analysis
Oceanic crust
Original Paper
Petrology
Rocks
Sciences of the Universe
Silica
Trace elements
Water content
Water resources management
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Summary:We experimentally investigated phase relations and phase compositions as well as the influence of water activity ( a H 2 O) and redox conditions on the equilibrium crystallization path within an oceanic dacitic potassium-depleted system at shallow pressure (200 MPa). Moreover, we measured the partitioning of trace elements between melt and plagioclase via secondary ion mass spectrometry for a highly evolved experiment (SiO 2  = 74.6 wt%). As starting material, we used a dacitic glass dredged at the Pacific-Antarctic Rise. Phase assemblages in natural high-silica systems reported from different locations of fast-spreading oceanic crust could be experimentally reproduced only in a relatively small range of temperature and melt-water content ( T ~950 °C; melt H 2 O 
ISSN:0010-7999
1432-0967
DOI:10.1007/s00410-016-1294-0