Abstract—

Oxygen isotope composition was studied in 33 monomineralic fractions of olivine from plagioclase lherzolite, dunite, troctolite, and olivine gabbronorite of the Yoko-Dovyren layered massif. The δ¹⁸O values of the least altered rocks not contaminated with crustal materials range within 5.8 ± 0.2‰ (n = 27). These values for the dunite contaminated with carbonate material are notably higher and average at 6.2 ± 0.3‰. This is similar to characteristics of the Bushveld and Jinchuan mineralized complexes. Using the COMAGMAT-5 model, the temperatures of equilibrium of 98% crystals with late portions of the residual melts were evaluated at 1131–1266°C (1176 ± 34°C on average). These estimates are viewed as the closing temperatures of the cumulate systems with respect to the efficient exchange of ¹⁸O and ¹⁶O isotopes between olivine and mobile melt/fluid. For the uncontaminated systems, the δ¹⁸O values of the parental melt calculated using the modeled temperatures are 6.6 ± 0.2‰, and are 7.1 ± 0.3 ‰ for melts with signatures of crustal contamination. Such relations are consistent with insignificant (no more than a few percent) contamination of the parental magmas with carbonate materials from the host rocks.

中文翻译：

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俄罗斯北跨贝卡利亚地区洋子-多维伦层状地块堆积物中橄榄石和熔体中的氧同位素组成

摘要-

在Yoko-Dovyren层状地块的斜长石斜长石，榴辉石，滑石和橄榄石辉长岩的33个单矿物级分橄榄石中研究了氧同位素组成。的δ ^18个的至少改变岩石的不沾染地壳物质O值范围内5.8±0.2‰（Ñ= 27）。这些被碳酸盐材料污染的辉光石的值明显更高，平均值为6.2±0.3‰。这类似于布什维尔德和金川矿化复合体的特征。使用COMAGMAT-5模型，在1131–1266°C（平均1176±34°C）下评估了98％晶体与剩余部分熔融物的平衡温度。这些估计值被视为相对于橄榄石和流动熔体/流体之间有效交换¹⁸ O和¹⁶ O同位素的累积系统的关闭温度。对于未受污染的系统中，δ ¹⁸使用模拟温度计算出的母体熔体的O值为6.6±0.2‰，对于具有地壳污染特征的熔体，其O值为7.1±0.3‰。这种关系与母岩中碳酸盐物质对母岩浆的微不足道的污染（不超过百分之几）一致。