论文部分内容阅读
在龙木错-双湖-澜沧江缝合带北侧,沿青海省囊谦县尕羊及其以西,新发现呈北西向带状分布的晚二叠世正长花岗岩侵入体。其岩性为中细粒含白云母正长花岗岩,岩石以酸性程度高、富硅、富碱、富铝及非常高的稀土含量为特点,岩石的铝过饱和指数ASI平均值达1.166,CIPW标准矿物中刚玉分子平均为5.08,为典型的高钾钙碱性系列的过铝质花岗岩。其岩石类型相当MPG含白云母过铝质花岗岩类;岩石ΣREE高达466.55×10-6～682.80×10-6,具有强的Eu负异常,δEu平均值为0.06,微量元素含量富不相容元素(LILE),贫高场强元素(HFSE),具有典型的S型花岗岩的特征,与冈底斯碰撞花岗岩特征近一致,构造分析相当于Maniar花岗岩分类中的CCG花岗岩(大陆碰撞花岗岩)。在尕羊正长花岗岩中获得了251.4±0.6Ma的TIMS法锆石U-Pb同位素年龄,其形成时代为晚二叠世,与在乌兰乌拉湖-澜沧江结合带内获得的251.5±2.6Ma和249±49Ma热年代信息一致,反映晚二叠世—早三叠世构造热事件的存在,可能属于晚二叠世—早三叠世乌兰乌拉湖-澜沧江结合带陆-陆碰撞的产物。
On the north side of the Longmucuo-Shuanghu-Lancang suture belt, a late-Permian granite intrusive belt newly discovered in the northwestern zonal distribution along Gaolan and its west of Qinqian County, Qinghai Province was discovered. Its lithology is fine-grained muscovite-bearing granite. The rocks are characterized by high acidity, rich in silicon, alkali-rich, rich in aluminum and very high REI. The mean value of ASI of rock is 1.166, and the average value of CIPW The standard mineral corundum molecules average 5.08, is a typical high potassium calc-alkaline series of peraluminous granite. Its MPG-type rocks are similar to muscovite-hosted peraluminous granites. The ΣREE of rocks is as high as 466.55 × 10-6 ~ 682.80 × 10-6 with strong negative Eu anomalies, with an average of δEu of 0.06 and elements with incompatible trace elements LILE, HFSE, and typical S-type granites are nearly identical with the Gangdese collisional granite. The tectonic analysis is equivalent to the CCG granite (continental collision granite) in the Maniar granite classification. The TIMS zircon U-Pb isotopic age of 251.4 ± 0.6Ma was obtained from the granitic granite in the Gaoyang Sheyang, the age of which was Late Permian and was 251.5 ± 2.6Ma in the Wulanhura-Lancangjiang belt It is consistent with the information of the 249 ± 49 Ma thermal age that the tectonic thermal events of the Late Permian-Early Triassic may belong to the continental-continental collision products of the Ulan-Ula-Lancangjiang belt during the Late Permian-Early Triassic .