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首页> 外文期刊>South African Journal of Geology: Being the Transaction of the Geological Society of South African: Syndie die Verhandelinge van die Geologiese Vereniging van Suid-Afrika >Majorite-indicative ultradeep (>300 km) xenoliths with spinel associations from the Jagersfontein kimberlite, South Africa.
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Majorite-indicative ultradeep (>300 km) xenoliths with spinel associations from the Jagersfontein kimberlite, South Africa.

机译：多米达特的UltraDeep（> 300公里）Xenoliths与来自Jagersfontein Kimberlite，南非的尖晶石协会。

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Our earlier studies continued in a diligent search for rare ultradeep xenoliths in the kimberlite diatreme at Jagersfontein. The search has met with moderate success insofar as 20 majorite-bearing (decomposed to *gt + lamellar px) xenoliths are identified. Discrete gts (1 to 2 cm), gt-rich layers (2 to 3 cm) in lherzolites, and rare megacrystic gts (>3 cm) from xenoliths characterize the ultradeep suite. Pyroxene lamellae are crystallographically controlled along {111} gt planes, but px may also be prismatic, lensoidal, coarsely graphic, or annular to jigsaw, rather than 120° dihedral textures, are typical. Gt ranges from Pyr68-74 mole% and CaO - Cr2O3 relations, with two exceptions, are distinctly lherzolitic. Cpx = Wo37-46 mole%, Jd3-19 mole%, with 0.4 to 2.4 wt% Cr2O3; opx = 92 to 95 mole% en, and ol averages 92.5 mole% with maximum wt% 0.1 CaO, 0.4 NiO, and 0.1 Cr2O3. A new class of 10 ultradeep xenoliths has lamellar spinel (Cr/Cr + Al = 0.74; Mg/Mg + Fe = 0.58) in addition to cpx with gt >3wt% Cr2O3 (c.f. 0.5 to 1.5 for sp-free types). Five samples are texturally linked but are compositional outliers to the central body of data: two are sp hosts (Cr# 0.69, Mg# 0.76) and (Cr# 0.74, Mg# 0.57) to gt (Pyr72) + cpx (Jd14); one is a gt megacryst (Pyr80) with sp (Cr# 57, Mg# 69); and the remaining two are unusually rich in chromium with gt = 7.3 to 8.2 wt% Cr2O3, rimmed by cpx (2.3 to 3.3 wt% Cr2O3). In addition, there are 17 xenoliths with compositional affinities to the ultradeep suite but lacking the texturally diagnostic lamellar intergrowths of cpx in gt are possibly completely equilibrated to gt + irregular cpx. Results from the new collection substantiate our earlier conclusions that the mantle was sampled by the Jagersfontein kimberlite from the lower lithosphere (250 to 350 km) and the transition zone (435 km) with diagnostic high P-T majorite in lherzolite that decomposed to gt + px at one or more interruptive stations (e.g. lithosphere-asthenosphere b
机译：我们早期的研究继续在Jagersfontein的Kimberlite Dytreme中寻求稀有的孤立纯氧化物。搜索已达到适度的成功，只要鉴定了20多元轴承（分解为* GT +层压PX）Xenoliths。在Lherzolites中离散GTS（1至2cm），富含GT的层（2至3cm），以及XenoLiths的稀有芒果GTS（> 3cm）的特征在于UltraDeep套件。辉石薄片沿{111} GT平面晶体地控制，但PX也可以是棱柱形的，透明度，粗图形的，或环形到GT;拼图，而不是120°Dihedral纹理，是典型的。 GT范围来自Pyr68-74摩尔％和CAO - CR2O3关系，有两个例外，是明确的Lherzolitic。 CPX = WO37-46摩尔％，JD3-19摩尔％，0.4至2.4wt％CR2O3; OPX = 92至95摩尔％EN，OL平均值92.5摩尔％，最大wt％0.1 caO，0.4nio和0.1cr2O3。除了具有GT> 3wt％CR2O3（C.f.0.5至1.5的CPX之外，还具有层状尖眼（Cr / Cr + Al = 0.74; Mg / Mg + Fe = 0.58）。五个样品是纹理相关的，但是数据的组成异常是数据的组成异常：两个是SP主机（Cr＃0.69，Mg＃0.76）和（Cr＃0.74，Mg＃0.57）至GT（Pyr72）+ CPX（JD14）;一个是gt egacryst（pyr80），sp（cr＃57，mg＃69）;其余的两者在铬中具有GT = 7.3至8.2wt％CR2O3的铬异常，由CPX边缘（2.3至3.3wt％CR2O3）。此外，有17个Xenoliths对UltraDeep套件的组成亲和力，但缺乏GT中的CPX的纹理诊断层状生殖器可能完全平衡至GT +不规则CPX。新收藏的结果证实了我们早期的结论，即jagersfontein金伯利矿来自较低的岩石圈（250至350 km）和过渡带（435 km）的jagersfontein金伯利塔在Lherzolite中诊断为Gt + Px一个或多个中断站（例如岩石圈 - 哮喘腰

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