【作者】 杨高学；

【导师】 李永军；

【作者基本信息】 长安大学 ， 构造地质学， 2008， 硕士

【摘要】 克拉麦里造山带位于新疆北部,由西伯利亚板块和准噶尔板块碰撞缝合形成,是中亚构造框架一个非常重要的构造单元。经历了早古生代与晚古生代两大构造旋回作用,多次开合,每次开合都形成一套沟弧盆体系。在这种构造背景下,广泛发育晚石炭世-早二叠世富碱酸性侵入岩,形成了卡拉麦里富碱花岗岩带。本文在前人研究基础上,对卡拉麦里富碱花岗岩带中的花岗岩体进行了归并和序列划分,并对岩浆序列的归并原则及依据、岩浆序列的具体特征、岩浆序列的同位素年龄、岩浆序列形成的构造环境及岩浆演化分别进行分析讨论,取得以下进展:1.在前人研究成果基础上,本文将卡拉麦里地区的花岗岩类详细划分为黄羊山序列、贝勒库都克序列、库布苏南序列和锡矿北斑岩序列。2.研究确认前人提及的“萨北岩体”和“苏吉泉岩体”只仅仅是黄羊山序列的一个组成部分,而并非单独岩体,重新确立的黄羊山序列包括中粒黑云母碱长花岗岩(原“苏吉泉岩体”)、中粒角闪石碱长花岗岩、中粒钠铁闪石碱长花岗岩、中细粒钠铁闪石碱长花岗岩(原“萨北岩体”)、细粒黑云母碱长花岗岩和细粒混合花岗岩(含石墨)。3.对区内四个序列进行了LA-ICP-MS锆石U-Pb测年。黄羊山序列中中粒钠铁闪石碱长花岗岩及包体年龄分别为311±12Ma,306±7Ma,中细粒钠铁闪石碱长花岗岩年龄为313±2Ma,中粒黑云母碱长花岗岩年龄为304±2Ma,中粒角闪石碱长花岗岩年龄为300Ma～305Ma,在误差范围内一致,时代属于晚石炭世;贝勒库都克序列年龄为283±9Ma;库布苏南序列以及包体年龄分别为287±2Ma和286±3Ma;锡矿北斑岩序列年龄为277±11Ma。可见黄羊山序列形成较早,而贝勒库都克序列和库布苏南序列次之,最晚期为锡矿北斑岩序列,总体上在晚石炭世-早二叠世,属于东准噶尔后碰撞深成岩浆活动范围(330～265Ma)。高精度锆石U-Pb测年,在获得可靠的资料的同时,丰富了区内花岗岩年龄的资料,最为重要的是为建立准噶尔地区构造格架和恢复岩浆演化事件提供最可靠最真实的证据。4.岩石学和岩石地球化学研究表明,四个序列具有高硅、富碱、低铝、高分异的特征。在SiO2-AR图中,黄羊山序列、贝勒库都克序列和锡矿北斑岩序列均显示碱性系列花岗岩,A/NK-A/CNK图中显示准铝质的特点,均具有高的FeOt/MgO、10000×Ga/Al和Zr+Nb+Ce+Y值,具有准铝质A型花岗岩和碱性系花岗岩特点。而库布苏南序列属于准铝质钙碱性系列花岗岩。5.微量元素研究表明,卡拉麦里花岗岩具有富集Rb、K、Th等大离子亲石元素及Zr、Hf等高场强元素,亏损Ba、Sr、Nb、Eu等元素的特征,具有不明显的Nb-Ta槽,有极强的Eu亏损,稀土元素球粒陨石标准化曲线为右倾“海鸥”型,曲线形态大致相同。6.从花岗岩类构造环境判别图的研究总结得出,黄羊山序列、贝勒库都克序列和锡矿北斑岩序列形成环境为后碰撞的伸展环境,而库布苏南序列具有火山弧花岗岩的印记,但是不属于火山弧花岗岩,可能是岩浆混合的结果。7.卡拉麦里花岗岩记录了东准噶尔卡拉麦里地区“软碰撞”后陆内均衡调整的过程,因此,它既具有岛弧花岗岩的印记,也具有后碰撞花岗岩的特征,卡拉麦里花岗岩的研究对建立准噶尔地区构造格架和恢复岩浆演化事件有重要意义。8.在综合研究的基础上,提出了卡拉麦里花岗岩混合成因模式。初步研究认为卡拉麦里花岗岩是壳-幔共同作用的结果,黄羊山序列和库布苏南序列中大量发育的包体是岩浆混合的记录者,而包体和寄主岩石锆石U-Pb年龄的一致以及高正的εNd(t)和低初始87Sr/86Sr比值提供了最有力的岩浆混合的证据。更多还原

【Abstract】 The Kalamaili area is located to north of the Xinjiang, united position of the Xiboliya plate and the Junggar plate, that is a important part in frame of the mid-asia tectonics. That experienced two tectonics cycle in Early Paleozoic and Late Paleozoic, many times close-open, each close-open process formatted trench-arc-basin system. In this tectonics setting, more lager area intrusive rock in late Carboniferous to early Permian distributed in Kalamaili area, formatted the granite belt. This paper basid on predecessor research, the author merger granite bodies and take part sequence, difference of analysis and discuss in merger principle, evience and mostly characters, isotope ages formative tectonic setting and magma evolvement of magma sequence. Gained achievement as follows:1. Basid on materials of the predecessor and the 1∶50000 investigate achievement, the paper take part sequence about granite in Kalamaili area: Huangyangshan sequence, Beilekuduke sequence, Kubusunan sequence and Xikuangbei sequence.2. Predecessor refered Sabei granite bodies and Sujiquan granite bodies not the independent bodies, but the only part of the Huangyangshan sequence. new sequence include medium granularity biotite alkali-feldspar granite(Sujiquan granite bodies);medium granularity amphibole alkali-feldspar granite;medium granularity arfvedsonite alkali-feldspar granite;medium-fine granularity arfvedsonite alkali-feldspar granite(Sabei granite bodies);fine granularity biotite alkali-feldspar granite and fine granularity mixing granite(containing graphite).3. High-precision LA-ICP-MS zircon U-Pb dating used in the four sequence in the research area. .In Huangyangshan sequence, host rock medium granularity arfvedsonite alkali-feldspar granite and enclaves LA-ICP-MS zircon U-Pb age is 311±12Ma,306±7Ma, medium-fine granularity arfvedsonite alkali-feldspar granite is 313±2Ma, medium granularity biotite alkali-feldspar granite is 304±2Ma, medium granularity amphibole alkali-feldspar granite is 300Ma～305Ma, the ages are very consistent within errors, belongs to Late Carboniferous; Beilekuduke sequence the age is 283±9Ma; Kubusunan sequence and enclaves age is 287±2Ma and 286±3Ma; Xikuangbei sequence age is 277±11Ma. We can see the Huangyangshan sequence formatted earlier, Beilekuduke and Kubusunan sequence next, the last is Xikuangbei sequence, as a whole, the time between late Carboniferous to early Permian, belongs to magma activity scope(330～ 265Ma). High-precision LA-ICP-MS zircon U-Pb dating age,not only acquisition the reliable material, but also enrich the age of granite in the area, most important is taking stronge evdent for rebuilding tectonic framework and recovering magma evolution in east Junggar.4. Petrology and the rock geochemistry reseach indicated, the four sequence have characteristics of high silicon, rich alkali, low aluminum, high differentiation. In SiO2-AR, Huangyangshan sequence, Beilekuduke sequence and Xikuangbei sequence all demonstrated alkali-granite series, on A/NK-A/CNK that have sub-aluminum feature, and high FeOt/MgO, 10000×Ga/Al and Zr+Nb+Ce+Y, belongs to sub-aluminum A type granite and alkali-granite. But Kubusunan sequence belongs to sub-aluminum calcium-alkali granite.5. Trace and rare earth element(REE) research indicated, Kalamaili granite(the four sequence) have rich Rb, K, Th et al large ion lithophile elements(LILE) and Zr, Hf et al high filed-strength element(sHFSE), deplete Ba, Sr, Nb, Eu et al, have weak Nb-Ta trough, more strength Eu deplete, chondrite-normalized REE pattern is right-incline“sea-gull”type, curved shape is similar.6. In tectonics environment diagram of granite concluded, Huangyangshan sequence, Beilekuduke sequence and Xikuangbei sequence formatted in extension of post-collision setting, but the Kubusunan sequence have volcanic-arc granite marking, that maybe come from magma mixing, not belongs to volcanic-arc granite.7. The granite record the process continental equilibrium adjust of“soft-collision”in Kalamaili area, so it have volcanic-arc and post-collision granite features, that take stronge evdent for rebuilding tectonic framework and recovering magma evolution , and have the implications for finding tin deposit of the Kalamaili area in East Junggar8. Basid on synthesized research, to propose the granite mixing formation mode in Kalamaili granite. Preliminary consider it is come from crust-mantle mixing, many enclaves in Huangyangshan sequence and Kubusunan sequence is the recorder of the magma mixing, host rock and enclaves have the same zircon U-Pb ages, and high positiveεNd(t), low initial 87Sr/86Sr ratios, that most powerful proof of magma mixing.更多还原