Journal
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
Volume 166, Issue 5, Pages 1469-1488Publisher
SPRINGER
DOI: 10.1007/s00410-013-0938-6
Keywords
Melt-peridotite reaction; Dissolution experiment; Dunite; Harzburgite; Mantle xenolith; North China Craton
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Funding
- NSF [EAR-0911501]
- Chinese Ministry of Science and Technology [2009CB825005]
- Natural Science Foundation of China [90814003, 91014004]
- State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Wuhan) [GPMR201104]
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Interaction between basaltic melts and peridotites has played an important role in modifying the lithospheric and asthenospheric mantle during magma genesis in a number of tectonic settings. Compositions of basaltic melts vary considerably and may play an important role in controlling the kinetics of melt-peridotite interaction. To better understand the effect of melt composition on melt-peridotite interaction, we conducted spinel lherzolite dissolution experiments at 2 GPa and 1,425 A degrees C using the dissolution couple method. The reacting melts include a basaltic andesite, a ferro-basalt, and an alkali basalt. Dissolution of lherzolite in the basaltic andesite and the ferro-basalt produced harzburgite-lherzolite sequences with a thin orthopyroxenite layer at the melt-harzburgite interface, whereas dissolution of lherzolite in the alkali basalt produced a dunite-harzburgite-lherzolite sequence. Systematic variations in mineral compositions across the lithological units are observed. These mineral compositional variations are attributed to grain-scale processes that involve dissolution, precipitation, and reprecipitation and depend strongly on reacting melt composition. Comparison of mineral compositional variations across the dissolution couples with those observed in mantle xenoliths from the North China Craton (NCC) helps to assess the spatial and temporal variations in the extent of siliceous melt and peridotite interaction in modifying the lithospheric mantle beneath the NCC. We found that such melt-rock interaction mainly took place in Early Cretaceous, and is responsible for the enrichment of pyroxene in the lithospheric mantle. Spatially, siliceous melt-peridotite interaction took place in the ancient orogens with thickened lower crust.
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