Large scale of Early Devonian magmatism was found in both east and west parts of Eastern Kunlun Orogen. But few studies were focused on its origin, geodynamic mechanism and relationship with Proto-tethys. This paper reports a typical Early Devonian intrusion from the east part of the Eastern Kunlun Orogen, which named Yuejinshan intrusion. The intrusion is mainly composed of monzogranite, granodiorite, some gabbro and cordierite-bearing granite, in which the nature of the first three rock types is the study object of this paper. Monzogranite and granodiorite samples are absence of hornblende and cordierite, and are characterized by relatively high contents of silicon and potassium, low contents of iron, magnesium and calcium, with moderate alumina saturation index (A/NCK = 1.0 similar to 1.1) and enrichment of large ion lithophile elements (LILE: Rb, Th and K) and distinct depletion of Ba, Sr, Nb, Ta, Ti, P, Eu, etc., belonging to peraluminous I-S transition type granites. Gabbros are characterized by significantly high contents of iron and titanium (the contents of FeOT and TiO2 are 8.17% similar to 12.70% and 4.50% similar to 6.54%, respectively), relatively high Cu contents (11.5 x 10(-6) similar to 30.6 x 10(-6)) and Cu/Ni values (1.41 similar to 6.41), enriched in LREE (the values of (La/Yb)(N) and LREE/HREE are 1.94 similar to 3.15 and 2.65 similar to 3.48, respectively), relatively low Mg-# (48 similar to 50), Cr (3.8 x 10(-6) similar to 60.4 x 10(-6)) and Ni (1.8 x 10(-6) similar to 12.5 x 10(-6)), Nb-Ta-Ti anomalies relative to primitive mantle. Monzogranites and granodiorites have relatively high I-Sr values (0.710 similar to 0.740 and 0.710, respectively), low epsilon(Nd) (t) values (-4.05 similar to -5.80 and -3.54 similar to -3.71, respectively) and old Nd istope model ages (the t(2DM) values are 1.47 similar to 1.62Ga and 1.43 similar to 1.45Ga, respectively). But the granodiorites have relatively higher epsilon(Hf)(t) values (-3.00 similar to 0.86). Gabbros have relatively high I-Sr values (0.711 similar to 0.714), low epsilon(Nd)(t) (-3.44 similar to -6.82) and more concentrated epsilon(Hf)(t) values (-2.19 similar to 1.05), which show the characteristics of an enriched mantle. The LA-ICP-MS zircon U-Pb analyses suggest that the formation ages of granodiorites and gabbros are 407 +/- 3Ma and 406 +/- 3Ma, respectively. With a comprehensive consideration on petrology, geochemistry, whole rock Sr-Nd isotopes and zircon Lu-Hf isotope analyses, and so on, we consider the formation of Yuejinshan pluton had experienced the following processes. Mantle derived magmas rose to the crust and provided enough heat for partial melting of crust materials (meta-greywacke) which produced S-type cordierite-bearing granites. Meanwhile; they mixed with crust derived magmas and produced I-S transition type monzogranite and granodiorite. The Yuejinshan and other Early Devonian magmatisms in the Eastern Kunlun orogeny have the same rock assemblages as typical post-collisional magmatisms and show obvious marks of mantle magmatism, which suggests the Eastern Kunlun orogeny at least begun its post-collisional extension in Early Devonian. Combining with regional studies, this paper suggests that Early Devonian is a critical period for the tectonic transformation of the Central orogenic belt (especially for Eastern Kunlun, North Qinling and Northern margin of Qaidam basin). During this period, the merging of terranes had finished and the tectonic framework begun to transfer from compression to extension.

研究发现,早泥盆世东昆仑造山带东段和西段均发育较大规模的岩浆活动。然而对于其成因、深部动力学机制以及与始特提斯构造演化的关联等问题一直缺乏系统的研究。本文以东昆仑东段地区跃进山岩体为例,探讨早泥盆世岩浆活动机理及其构造意义。该岩体主体由二长花岗岩和花岗闪长岩组成,含少量的辉长岩和含堇青石花岗岩,前三种岩性是本文的重点。其中,二长花岗岩和花岗闪长岩无角闪石和堇青石,具有高硅和钾,低铁、镁和钙,铝饱和指数(A/CNK)多数在1.0~1.1之间,富集大离子亲石元素(LILE: Rb、Th和K)和轻稀土(LREE),明显亏损Ba、Sr、Nb、Ta、Ti、P和Eu等元素,属过铝质I-S过渡型花岗岩;辉长岩具有显著高的Fe和Ti(FeO T 为8.17%~12.70%,TiO 2 为4.50%~6.54%)含量,高Cu(11.5×10 -6 ~30.6×10 -6 )和Cu/Ni值(1.41~6.41),相对富集的LREE((La/Yb) N 为1.94~3.15,LREE/HREE为2.65~3.48),相对低的Mg # (48~50)、Cr(3.8×10 -6 ~60.4×10 -6 )、Ni(1.8×10 -6 ~12.5×10 -6 )值,相对于原始地幔具有明显的Nb-Ta-Ti正异常。二长花岗岩和花岗闪长岩均具有相对高的I Sr 值(分别为0.710~0.740和0.710)、相对低的 ε Nd ( t )值(分别为-4.05~-5.80和-3.54~-3.71)和偏古老的 t 2DM (分别为1.47~1.62Ga和1.43~1.45Ga),但花岗闪长岩具有相对高的 ε Hf ( t ),其变化在-3.00~0.86。跃进山辉长岩具有相对高的I Sr (0.711~0.714)、相对低的 ε Nd ( t )值(-3.44~-6.82)和较为集中的 ε Hf ( t )值(-2.19~1.05),显示富集地幔的特征。本次利用LA-ICP-MS 锆石U-Pb定年方法获得花岗闪长岩的形成年龄为407±3Ma,辉长岩的形成年龄为406±3Ma。综合岩石学、地球化学和Sr-Nd-Hf同位素等多方面的指标,可以判断该岩体的形成为:幔源岩浆上侵至地壳,供热诱发古老的地壳物质部分熔融产生S型岩浆最终形成含堇青石花岗岩,同时与壳源熔体发生混合产生I-S过渡型岩浆并经历较高程度的分异最终形成二长花岗岩和花岗闪长岩。跃进山与东昆仑造山带其他地区早泥盆世岩浆活动均具有与典型后碰撞岩浆作用类似的岩石组合,并且显示很强的幔源岩浆作用的印记。这表明,至少从早泥盆世开始,东昆仑地区已经进入后碰撞的伸展阶段。综合区域上的研究成果,本文认为早泥盆世应为中央造山带(特别是东昆仑、北秦岭和柴北缘)始特斯构造体制转换的关键时期,这一时期相关地体的碰撞拼合已基本完成,区域构造体制由挤压开始转向伸展。

On the basis of systematic cataloging of boreholes of the Xiarihamu deposit, chromian spinels have been studied in this paper in order to provide new evidences for studying metallogenesis of the deposit. Thin section identification suggests that chromian spinels are closely intergrown with olivines, or distributed as grain or rounded crystal within the olivine and pyroxene crystals. Electron microprobe studies show that chromian spinels of the Xiarihamu deposit contain low contents of TiO 2 and Fe 2 O 3 , have largely variable Cr # (22 to 62)and Mg # values(22 to 60), with generally negative correlation between Cr # and Mg # values. Especially, the chromian spinels included in olivine crystals often contain relatively high Cr 2 O 3 contents. On the basis of compositions of the chromian spinels, it is inferred that the parental magma of the Xiarihamu deposit could be low Ti, high Mg tholeiitic magma which was derived from the ashospheric mantle. Based on the Fe 3+ -Cr-Al diagram and Mg # -Cr # diagram of spinel and the mineral assemblage and lithological association of the Xiarihamu deposit, it is believed that the deposit could be formed post-collisional extension environment rather than in island arc or active continental margin settings.

为给夏日哈木矿床成因研究提供新的依据，本文在系统岩心编录的基础上，对该矿床的铬尖晶石进行了研究。薄片鉴定表明，铬尖晶石与橄榄石紧密共生，呈粒状或浑圆状分布于橄榄石和辉石晶体内部。电子探针分析表明，铬尖晶石的TiO 2 及Fe 2 O 3 含量较低，Cr # 值与Mg # 值变化范围较大且二者呈负相关关系，包裹于橄榄石中的铬尖晶石具有较高的Cr 2 O 3 含量。由铬尖晶石成分推测该矿床母岩浆属于低Ti、高Mg拉斑玄武质岩浆，起源于软流圈地幔。铬尖晶石Fe 3+ -Cr-Al、Mg # -Cr # 图解和矿物岩石组合表明，夏日哈木矿床可能不是形成于岛弧环境，而可能形成于碰撞后的伸展环境。

Eclogites as lenses occur in the Proterozoic paragneiss at eastern segment of the East Kunlun orogen, with SiO 2 contents varying from 47% to 59% and Mg # from 0.45 to 0.51, implying that protoliths of the eclogites were basic-intermediate and highly fractionated. Chondrite-normalized REE patterns show slight enrichment and depleted in LREE ((La/Sm) N =1.42~1.72 and 0.8~0.88, respectively), with weakly negative anomaly of Eu ( δ Eu=0.85~0.95). The eclogites have positive whole-rock ε Nd ( t ) values of +0.51~+6.17 ( t =934Ma, age of protolith). The features that U-Yb-Hf concentrations as well as positive ε Hf ( t ) (+8~+10) of the zircons from protolith of the eclogites are similar to those from continental gabbros and continental tholeiitic basalt, indicating that the basic parental magma were derived from depleted mantle, contaminated by crust and highly fractionated during ascending to continent. Later they subducted and metamorphosed into eclogite. Therefore, the protoliths of the eclogites formed in continental margin setting, and represented the relics of subduction continent crust. This demonstrates that the East Kunlun orogen underwent continent-continent collision in the Early Paleozoic.

东昆仑东段温泉榴辉岩呈透镜状分布在片麻岩中,榴辉岩的SiO 2 含量为47%~59%,Mg # 指数为0.45~0.51,表明其原岩为分异程度较高的中-基性岩石,稀土元素显示为轻稀土富集型((La/Sm) N 比值为1.42~1.72)和轻稀土亏损型((La/Sm) N 比值为0.82~0.88),Eu轻微负异常( δ Eu=0.85~0.95),榴辉岩的 ε Nd ( t )值为+0.51~+6.17(原岩年龄 t =934Ma)。榴辉岩原岩锆石与陆壳辉长岩锆石的U-Yb-Hf值类似,且具有正的 ε Hf ( t )值(+8~+10),这些特征类似于大陆拉斑玄武质岩,岩浆来自亏损地幔,遭受了地壳物质的混染及较高程度的结晶分异,表明榴辉岩原岩形成于大陆边缘环境。因此,该榴辉岩代表了俯冲的陆壳,进一步证明了东昆仑早古生代发生过陆-陆碰撞造山作用。

We discuss the zircon U-Pb dating, whole-rock geochemical and zircon Hf isotope data of the dioritic intrusion (stocks) in the southeast of Xiarihamu ore district. The rock assembles of the intrusion include diorites and quartz diorites. Zircon U-Pb dating demonstrates that the concordant age of the zircon in the quartz diorite is (243±1) Ma (MSWD＝0.013), i.e., the late Early Triassic. Geochemically, the diorite and quartzdiorite are metaluminous and belong to the high-K calc-alkaline series. The diorite is enriched in LREE and relatively depleted in HREE ((La/Yb) N =8.7-12.7), and no obvious Eu anomaly ( δ Eu=0.84-1.01). Both the diorite and the quartz diorite are enriched in Rb, Ba, and K, and depleted in Nb, Ta, P, and Ti, with a variable ε Hf ( T ) values (from -1.0 to -0.9) and ancient T C DM ages (from 1.34 to 1.84 Ga). Combined with the discrimination diagram of experimental petrology studies, the authors suggest that their primary magma maybe derived from dehydration melting from a Meso-Proterozoic metabasaltic low crust source. Moreover, some contributions from enriched mantle materials maybe the main reason of a variable ε Hf ( T ) values and T C DM ages. Trace elements and their characteristic ratio values display that the dioritic intrusion was generated within an Andean-type active continental margin setting. Taken together, in the late period of Early Triassic, the middle uplifted basement in eastern Kunlun was in the late-stage of Andean-type active continental margin setting.

夏日哈木矿区的闪长质岩体呈岩株状出露于矿区南东，岩性主要为石英闪长岩和闪长岩。年代学研究表明，石英闪长岩中岩浆锆石LA-ICP-MS U[CD*2]Pb谐和年龄为(243±1 ) Ma，MSWD＝0.013，属早三叠世晚期。岩石学及化学成分显示其属于准铝质、高钾钙碱性系列闪长岩。稀土配分曲线呈现轻稀土元素相对富集的右倾分布特征((La/Yb) N =8.7~12.7)，无明显的Eu负异常( δ Eu=0.84~1.01)。岩石富集Rb、Ba、K等元素，而相对亏损Nb、Ta、P和Ti。岩石具有不均一的 ε Hf ( T )值(-9.0~-1.0)和古老的二阶段Hf模式年龄(1.34~1.84  Ga)。结合试验岩石学资料判别，闪长岩主要起源于中元古代玄武质下地壳脱水部分熔融，富集地幔组分的加入可能是导致 ε Hf ( T )值和Hf模式年龄不均一的主要原因。微量元素及特征比值显示岩体形成于安第斯型活动大陆边缘的构造环境。综合分析认为，早三叠世晚期东昆中隆起带整体处于俯冲晚期的安第斯型活动大陆边缘背景。

本文采用配备有 193nm Ar F准分子 (excimer)激光器的 Geo L as2 0 0 M剥蚀系统和 Elan6 10 0 DRC ICP- MS对 4个美国地质调查所 (USGS)玻璃标准参考物质以及 3个美国国家标准技术研究院 (NIST)人工合成硅酸盐玻璃标准参考物质中几乎覆盖整个质量数范围 (从 7L i到 2 38U)的 38个微量和 4个主量 (Na、Mg、Ti和 Mn)元素进行了分析。分析结果表明 ,无论是对 USGS还是 NIST玻璃 ,元素分析的相对标准偏差 RSDs和分析值与参考值之间的相对偏差 (RDs)一般优于 10 % ,RSD和RD较大的元素主要出现在含量很低或不均匀样品中。稀土元素的 RSD显示 ,除 AGV- 2 G可能存在不均匀现象外 ,其它所测样品在 6 0 μm尺度上 ,元素分布是均匀的。本研究证明 ,由于 ICP- MS具有 10 8cps(每秒计数 )的动态线性范围 ,本实验室的L A- ICPMS系统可定量分析含量在百分之几的主量元素及微量元素。分析精密度和准确度可与常规溶液雾化进样 ICP- MS方法相媲美

锆石U-Pb定年是同位素年代学研究中最常用的方法, 如何对所得到的年龄值给予合理的地质解释是锆石U-Pb年代学研究的重点. 本文对近年来锆石成因矿物学研究及其对U-Pb年龄解释的制约方面有关的进展进行了系统的总结和评述. 不同地质环境中形成的锆石具有不同的结构类型: 岩浆锆石具有典型的振荡环带和/或扇形分带结构; 变质锆石有其特征的内部结构, 主要有无分带、弱分带、云雾状分带、扇形分带、面状分带和斑杂状分带等, 不同成因变质锆石具有其特征的内部结构特点. 岩浆锆石的微量元素特征与其岩石类型有关, 从超基性岩到酸性岩中的锆石的微量元素含量逐渐升高; 不同成因变质锆石具有不同的微量元素特征, 变质锆石的微量元素特征可以反映变质锆石的形成环境. 通过锆石与石榴石之间微量元素的配分, 可以很好地确定含石榴石的高级变质岩中变质锆石形成的具体P-T条件. 锆石中原生包裹体矿物组成同样可以为锆石的形成环境提供明确的限定. 因此, 在进行锆石U-Pb定年的同时, 对锆石进行显微结构、微量元素特征和矿物包裹体成分等方面的综合研究, 限定锆石的形成环境, 能够为锆石U-Pb年龄的合理解释提供有效的制约.

Middle Triassic A-type granitoid and other types of granitoid in the central Kunlun region were formed respectively in post orogeny and collision-orogenic stage of southern Kunlun subplate subducting north. The occurrence of late Triassic muscovite/two-mica granites and S-, I- and A-type granitoids in the central Kunlun region, and I-type granitoid in northern margin of southern Kunlun region are the result of intracontinental subduction, in which the southern Kunlun fault is the underthrust zone. Late Triassic anorogenic A-type granites are a indication that intracontinental subduction of southern Kunlun subplate ended. Meanwhile, the I-, S- and A-type granitoids in the northern Kunlun region were formed by intracontinental subduction of the central Kunlun subplate along the Mid-Kunlun fault in late Triassic epoch. Early Triassic granitoid is not found. Therefore, the early-middle Triassic epoch in the eastern Kunlun area fell into the period of the southern Kunlun subplate underthrusting north along the central Kunlun fault. Both the southern Kunlun fault and the central Kunlun fault went through complete intracontinental subduction in late Triassic epoch.

研究表明：东昆仑未见早三叠世花岗岩出露；中三叠世花岗岩仅见于昆中区；晚三民花岗岩在昆北区１昆中区和昆南区广为分布。昆中区花岗岩（Ⅰ型）形成于昆南板片向北俯冲的碰撞造山阶段；其Ｓ型、Ａ型花岗岩的产出，是陆内俯冲作用的结果。昆北区出露的Ⅰ型、Ｓ型、Ａ型花岗岩，形成于昆中板片，在晚三叠世沿昆中断开明发生的陆内俯冲。Ａ型花岗岩的产出表明进入造山后阶段。因此，早、中三叠世昆南板片没昆南缝合带向北造山俯冲，Ａ

对青海省都兰县香日德南部东昆仑山区一带侵入于元古界苦海岩群的变形变质闪长岩体同时进行了锆石U-Pb和角闪石 40 Ar- 39 Ar年代学研究. 单颗粒锆石U-Pb年龄为(446.5 ± 9.1) Ma; 角闪石Ar坪年龄为(488.0 ± 1.2) Ma, 等时线年龄为(488.9 ± 5.6) Ma, K-Ar年龄为(462.8 ± 8.8) Ma. 角闪石的K-Ar年龄和良好的 40 Ar- 39 Ar坪年龄及等时线年龄显著高于锆石的U-Pb年龄, 可能为含过剩Ar的结果, 不代表岩石的变形变质年代. 锆石的U-Pb年龄可代表岩体的侵入年代, 表明从格尔木经诺木洪到本区香日德以南的东昆仑构造带存在一条早古生代岩浆岩带.