Collerson KD, Hapugoda S, Kamber BS, Williams Q
Department of Earth Sciences, The University of Queensland, Brisbane, Qld 4072, Australia. Department of Earth Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
Science. 2000 May 19;288(5469):1215-23. doi: 10.1126/science.288.5469.1215.
Rocks containing high-pressure mineral assemblages derived from the mantle transition zone between depths of about 400 and 670 kilometers occur as xenoliths and megacrysts on the island of Malaita in the southwest Pacific on the Ontong Java Plateau. Observed ultrahigh pressure mineral chemistries include majorite, calcium- and magnesium-perovskite, aluminous silicate phases, and microdiamond. Based on an empirical barometer, majoritic garnets in these xenoliths record pressures of up to 22 gigapascal. The occurrence of material with perovskite chemistry and several enigmatic aluminous phases indicates pressures of up to 27 gigapascal. Samples were brought to the surface at about 34 million years ago by potassic ultramafic magmas, which evidently originated in the lower mantle.
含有源自约400至670公里深处地幔过渡带的高压矿物组合的岩石，以捕虏体和巨晶的形式出现在西南太平洋翁通爪哇高原上的马莱塔岛。观察到的超高压矿物化学成分包括镁铁榴石、钙钛矿和镁钙钛矿、铝硅酸盐相以及微金刚石。根据经验压力计，这些捕虏体中的镁铁榴石记录的压力高达22吉帕斯卡。具有钙钛矿化学成分和几种神秘铝相的物质的出现表明压力高达27吉帕斯卡。这些样品在约3400万年前由钾质超镁铁质岩浆带到地表，这些岩浆显然起源于下地幔。
