摘要:
苏普特片麻岩为含堇青石、矽线石及红柱石等变质矿物的眼球状、条纹条带状黑云斜长片麻岩、黑云二长片麻岩、二云母片麻岩等。其SiO2含量为63.12%~68.34%,Al2O3为13.64%~15.91%,TiO2为0.538%~0.772%,TFe2O3为6%左右,MgO含量较高,多数样品为3%左右。根据其岩石化学特征判断,原岩为泥质岩、砂岩等沉积岩。苏普特片麻岩稀土元素含量较高,ΣREE为155.21×10-6~271.93×10-6,轻稀土元素富集,具中等程度的负Eu异常;在以北美页岩(NASC)标准化的稀土配分型式图上具有较平缓的配分曲线,无明显的Ce、Eu异常。依据地球化学特征,推断其原岩的形成环境为活动大陆边缘。苏普特片麻岩中锆石具有岩浆锆石特征,其U-Pb SHRIMP年龄为282 Ma,可能代表了早二叠世的一次构造-岩浆-混合岩化事件。
Abstract:
The Supute gneiss complex is composed of andalusite,sillimanite,and cord ierite.It contains SiO2 ranging from 63.1% to 68.3%,Al2O3 from 13.64% to 15.91%,TiO2 from 0.53% to 0.77%,and relatively high MgO(mostly～3%).In line with their geochemical composition,they are metamorphized products of greywackes.For the trace elements,their total REE ranges from 155ppm to 272ppm and the LREE are enriched relative to the HREE with middle Eu negative anomalies.NASC normalized REE patterns of the Supute gneiss are coherently flat with insignificant Ce and Eu anomalies.Their geochemistry suggests that they are formed a long an active continental margin.Zircons from Supute gneiss show typical characteristics crystallized from magma and a SHR MIPU-Pb age of 282 Ma.Thus,the Supute gneiss represents an early Permian tectonomagmatic event.
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