论文部分内容阅读
达巴特花岗斑岩侵入体位于西天山北部的赛里木湖北部,构造上属于准葛尔板块与伊犁-中天山板块之间的造山带。达巴特花岗岩斑岩具有 A 型花岗岩的特征,如高硅(SiO_2=75.38%～77.61%)、碱(Na_2O+K_2O=8.26%～10.10%)和Fe/(Fe+Mg)(0.91～0.98),但低 Al_2O_3(12.04～12.9l%)和 CaO(0.03%～0.42%),富集 Rb、Th、U 等大离子亲石元素和Nh、Ta、Zr、Hf 等高场强元素,(Ga/Al)×10~4值变化于3.19～3.40之间,具有明显的负 Eu、Ba 和 Sr 异常,稀土配分显示“海鸥型”特征。达巴特花岗岩斑岩具有较高的 Rb/Nb 和 Y/Nh 比值,显示了 A_2型花岗岩的特征。LA-ICP-MS 锆石 U-Pb 测年结果显示达巴特岩体的侵位年龄为288.9±2.3Ma,并且一些锆石具有老的核(319.0±4.7),暗示花岗岩斑的源岩中可能包含有石炭纪的岩浆岩。结合区域地质和岩浆岩资料,我们认为西天山早二叠世处于伸展的背景中,可能与造山带后碰撞阶段的演化有关。
The Dambert granite porphyry intrusion is located in the northern part of the northern part of the western part of the western Tianshan Mountains and is structurally formed between the Junggar plate and the Yili-Tianshan plate. The Tatart granite porphyry has the characteristics of A-type granites such as high silicon (SiO 2 = 75.38% -77.61%), alkali (Na 2 O + K 2 O = 8.26% -10.10%) and Fe / (Fe + Mg) (12.04 ~ 12.91%) and CaO (0.03% ~ 0.42%), enriched in large ion lithophile elements such as Rb, Th and U and high field strength elements such as Nh, Ta, Zr and Hf, / Al) × 10-4 values vary between 3.19 and 3.40, with obvious negative Eu, Ba and Sr anomalies, and the REE shows “gull ” characteristics. The Dambert granite porphyry has higher ratios of Rb / Nb and Y / Nh and shows the characteristics of A_2 type granites. LA-ICP-MS zircon U-Pb dating results show that the emplacement age of the Tatartite rock mass is 288.9 ± 2.3Ma, and some zircons have old nuclei (319.0 ± 4.7), suggesting that the source rocks of granite patches may Contains the Carboniferous magmatic rocks. Combined with regional geology and magmatic rock data, we believe that the Early Permian in the western Tianshan is in a stretching background, which may be related to the evolution of the orogenic belt in the post-collision stage.