Origin of josephinite.
Origin of josephinite.
复制标题
约瑟芬石的起源。
DOI：
10.2343/geochemj.13.41
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发表时间：
1979
影响因子：
0.8
通讯作者：
M. S. Weathers
中科院分区：
文献类型：
--
作者：
J. Bird;M. S. Weathers
(BIRD和Weathers，1975 a）。虽然大多数的镁橄榄石样品都有一定程度的蚀变，但蚀变最少的镁橄榄石由几种镍铁合金组成，其中一种与钙铁榴石石榴石共生，一种铁钴合金，以及少量的铁镍砷化物，铁镍铜硫化物和各种未识别的相。共生的金属garent组合显然是唯一的josephinite。蚀变相包括蛇纹石矿物和磁铁矿。约瑟芬岩作为碎屑出现在约瑟芬橄榄岩上的几条溪流中;基岩包括剪切蛇纹岩带和橄榄岩内的玄武质至闪长岩脉。这是一个合理的假设，josephinite卵石必须与一个或多个这些岩石，但是，没有明确的，大josephinite样品已被发现在基岩。BIRD和WEATHERS（1975 a）认为，由于其显著的、明显独特的成分和结构，以及与仰冲地幔的共生关系，钾霞石来源于地幔，可以认为是深部地幔。随后，DICK（1974）、THORNBER和HAGGERTY（1976）、BOTTO和莫里森（1976），继RAMDOHR（1950）之后，认为约瑟芬橄榄岩是由硅酸盐或硫化物在约瑟芬橄榄岩的蛇纹石化过程中还原而形成的。目前，关于Josephinite的起源有两种观点：1）Josephinite是一种低温、同步蛇纹石化过程的产物，与Awaruite相似; 2）由于其矿物组成、结构和岩石组合，Josephinite早于Josephine橄榄岩的蛇纹石化（仰冲蛇绿岩），与约瑟芬橄榄岩的起源有关，并来自原始地幔，可以想象，从深至核幔边界。最近在josephinite中发现了过量的3 He，21 Ne和129 Ne，并被解释为指示地幔居住，也许是这种岩石的原始年龄（DOWNING等人，1977; BOCHSLER等人，1978年）。我们继续提出了一个地幔衍生的josephinite，此外，我们认为，josephinite是原始材料在合作到地球在地球吸积。
(BIRD and WEATHERS, 1975a). Although most samples of josephinite are somewhat altered, least-altered josephinite consists of several nickel-iron alloys, one intergrown with andradite garnet, an iron-cobalt alloy, and minor amounts of iron-nickel arsenides, iron-nickel-copper sulphides, and various unidentified phases. The intergrown metal-garent assemblage is apparently unique to josephinite. Alteration phases include serpentine minerals and magnetite. Josephinite occurs as detritus in several streams that originate and flow on the Josephine Peridotite; bedrock includes sheared serpentinite zones and basaltic to dioritic dikes within the peridotite. It is a reasonable assumption that the josephinite pebbles must be associated with one or more of these rocks; however, no unequivocal, large josephinite samples have been found within bedrock. BIRD and WEATHERS (1975a) proposed that because of its remarkable and apparently unique com position and textures, and its association with obducted mantle, josephinite has been derived from the mantle, conceivably the deep-mantle. Subsequently, DICK (1974), THORNBER and HAGGERTY (1976) and BOTTO and MORRISON (1976), following RAMDOHR (1950), argued that josephinite was formed by reduc tion of silicates, or sulphides, during serpentinization of the Josephine Peridotite. Currently, there are two views concerning the origin of josephinite: 1) josephinite is a product of low-temperature, syn serpentinization processes and is comparable with awaruite 2) because of its mineral composition, textures, and rock associations, josephinite pre-dated serpentinization of the Josephine Peridotite (obducted ophiolite), was related to the origin of the Josephine Peridotite, and was derived from the primitive mantle, conceivably from as deep as the core-mantle boundary. Excesses of 3He, 21Ne and 129Xe have recently been found in josephinite and have been interpreted to indicate a mantle residence and, perhaps, a primordial age for this rock (DOWNING et al., 1977; BOCHSLER et al., 1978). We continue to propose a mantle derivation of josephinite; additionally, we suggest that josephinite was primitive material in corporated into the earth during earth accretion.