Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mizukami, T. Articles by Kagi, H. Search for Related Content GeoRef GeoRef Citation

Forearc diamond from Japan

¹ Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan
² Geochemical Laboratory, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan

Convergent margins are not generally considered to be suitable places for the formation of diamond and its transport to Earth's surface. Microdiamonds found in xenoliths within a lamprophyre dike in southwest Japan show that this assumption is incorrect and, furthermore, that diamond occurs in a wider range of geological settings than previously realized. Petrological constraints show that these diamond-bearing minerals rose from depths of around 160 km (5.5. GPa) and cooled from temperatures of 1500 °C. The location of the diamond-bearing rocks in the forearc and close to the subducting plate requires the existence of mantle up-flow, which brought the diamond to shallow mantle levels before traveling 100-km-scale horizontal distances. If the dimensions of this flow are large, it can help explain both forearc magmatism and perhaps the development of subduction zones hot enough to melt sediments.

Key Words: diamond • forearc • mantle flow • micro-Raman spectroscopy