Melting Systematics of Modally Variable, Compositionally Intermediate Peridotites and the Effects of Mineral Fertility

Piston-cylinder experiments were performed at 10 kbar to investigatethe near-solidus partial melting systematics of modally variableperidotites. Starting materials consisted of compositionallyintermediate (i.e. containing moderate incompatible elementabundances) minerals, separated from a spinel lherzolite xenolithfrom Mt. Noorat, SE Australia, and recombined to create fivestarting mixtures varying in their proportions of olivine, orthopyroxene,clinopyroxene (Cpx), and spinel. These modes match those ofstarting materials made with fertile (FER) minerals from a differentxenolith, investigated in a companion study. A layer of vitreouscarbon spheres provided a melt sink in the experiments. Solidustemperatures for the five peridotites are similar and estimatedto be     

Queen(s‘) Street or Ponsonby Poofters? Embodied HERO Parade Sites

In this paper I highlight some spatial and body politics of the HERO parade, Aotearoa/New Zealand's biggest gay pride parade. The proposed site change of the HERO parade, from Queen Street to Ponsonby Road, was debated at length in local newspapers. This debate can be theorised as contingent on western hierarchical dualisms such as mind/body, public/ private, straight/gay. 1 offer an embodied geography through a focus on the constitutive relationship between bodies and places.     

Vapour-Absent Melting from 10 to 20 kbar of Crustal Rocks that Contain Multiple Hydrous Phases: Implications for Anatexis in the Deep to Very Deep Continental Crust and Active Continental Margins

Dehydration-melting experiments from 10 to 20 kbar were performedon a metavolcanoclastic rock containing (in vol. %) biotite(16), amphibole (15) and epidote (13) in addition to plagioclaseand quartz. At 10 and 12.5 kbar traces of biotite and epidoteremain at 850C, amphibole becomes more abundant, and the meltfraction is 5–10 vol. %. These relationships reflect thatthe thermal stability of biotite is lowered in the presenceof epidote through the dehydration-melting reaction biotite+epidote+quartz=amphibole+garnet+alkalifeldspar+melt. Amphibole dehydration-melting produces an additional25 vol. % melt between 875 and 925C. At 15 kbar and 875C themelt fraction is 22 vol. %, amphibole is present in trace amounts,and biotite constitutes 8 vol. %. These relationships suggestthat the curves marking biotite- and amphibole-out intersectclose to 15 kbar, and that the fertility of the rock increasesfrom 10 to 15 kbar at 850C. At 20 kbar the melt fraction isonly 5 vol. % at 850C, amphibole is transformed to omphaciteand biotite constitutes 5% of the mode. This result shows thatthe fertility decreases from 15 to 20 kbar at 850C, mainlybecause much Na is locked up in omphacite. Along active continentalmargins, intrusion of hot mantle-derived magmas is common, andmelting of metavolcanoclastic rocks may be an important granitoid-formingprocess. Intersection of the amphibole- and biotite-out reactionsbetween 12.5 and 15 kbar suggests that fusion of biotite- andhornblende-bearing rocks can produce magmas ranging in compositionfrom granitic (biotite dehydration-melting) to granodioritic(amphibole dehydration-melting) in either order depending onpressure. KEY WORDS: amphibole; biotite; dehydration-melting; epidote; metavolcanoclastic rock ^*Corresponding author.