Mafic and ultramafic mantle and deep crustal xenoliths from Banks Peninsula, South Island, New Zealand
Mafic and ultramafic mantle and deep crustal xenoliths from Banks Peninsula, South Island, New Zealand
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新西兰南岛班克斯半岛的镁铁质和超镁铁质地幔以及深部地壳捕虏体
DOI：
10.1080/00288306.1993.9514570
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发表时间：
1993
影响因子：
2.2
通讯作者：
S. Weaver
中科院分区：
文献类型：
--
作者：
R. J. Sewell;B. Hobden;S. Weaver
摘要班克斯半岛阿卡罗阿火山东侧形成勒邦湾峰的碧玄岩塞体中产出有尖晶石二辉橄榄岩、伟氏岩、镁橄榄石、辉石岩和变辉长岩（镁铁质麻粒岩）等镁铁质和超镁铁质包体。尖晶石二辉橄榄岩属于Cr‐透辉石捕虏体组，并被解释为代表来自c深度的亏损上地幔碎片。六十公里。辉石岩属于韦尔石系列铝辉石捕虏体套，可能代表侵入壳幔边界或附近的镁铁质岩浆分异形成的玄武质堆晶。辉长岩成分的镁铁质麻粒岩代表构造作用和部分重结晶的下地壳玄武质堆晶岩。捕虏体的矿物和岩石化学表明，班克斯半岛岩浆的化学和矿物学变化可能反映了地壳下玄武岩“底板”的发展。这可能解释了从广泛修改到相对未修改的地幔岩浆的趋势。
Abstract Mafic and ultramafic xenoliths of spinel lherzolite, wehrlite, websterite, pyroxenite, and metagabbro (mafic granulite) occur in a basanite plug forming Le Bons Bay Peak on the eastern flanks of Akaroa volcano, Banks Peninsula. Spinel lherzolites are assigned to the Cr‐diopside xenolith suite and are interpreted to represent fragments of depleted upper mantle derived from a depth of c. 60 km. Pyroxenites belong to the wehrlite series Al‐augite xenolith suite and may represent basaltic cumulates derived from differentiation of mafic magma intruded at or near the crust/ mantle boundary. Mafic granulite of gabbroic composition represents a tectonised and partly recrystallised lower crustal basaltic cumulate. Mineral and bulk rock chemistry of the xenoliths suggests that chemical and mineralogical variation in Banks Peninsula magmas could reflect the development of a subcrustal basaltic “underplate”. This might explain the trend from extensively modified to relatively unmodified mantle‐derived magmas...