The chemical composition of a barren biotite granite, a two-mica granite, and a rare metal-bearing pegmatite (the No. 3 vein in Keketuohai, Altay Mountains, northwest China), along with mineral separates of apatite and mica, were analyzed and compared in the present work. Bulk chemistries of biotite granite, two-mica granite, and pegmatite rim are consistent with fractional crystallization trend from granites toward pegmatite. Changes in pegmatite composition can be explained mainly by fractional crystallization of biotite. Rb–Sr isochrons yield 248.8±7.5 Ma for the biotite granite, 247.8±6.3 Ma for the two-mica granite, and 218.4±5.8 Ma for the pegmatite rim. Similar geochemical characteristics, including initial εNd (T) values (ranging from -0.76 to -3.04) for apatites, similar initial 3Nd (T) values for whole-rock samples of studied granites and pegmatite (ranged from-1.40 to-3.21) and for biotites from granites (ranged from-2.75 to-3.15) suggest that these rocks were derived from a common magma source. Old continental crust may have played a significant role in magma generation. Based on these data, we interpret the evolution of the Keketuohai granite–pegmatite by magma differentiation from a common source. Biotite granite was the first to crystallize, followed by two-mica granites. The residual melt was probably stored in a granitic batholith. The pegmatite veins were injected ～30 M. y. later during another episodic tectono-magmatic event in the Altay Mountains. © 2005 Elsevier Ltd. All rights reserved.

Clinopyroxene phenocrysts in the Kokchetav trachybasalts are variable in composition and textures. Two distinctive cores are recognized: diopside cores and green salite cores. The diopside cores with Mg# of 80–90 are mantled by colorless salite rims with Mg# of 70–80. The green salite cores have especially low Mg# (<70) but high Al and Ti contents. A Mg-rich band (Mg# = 82–90) usually occurs between a green salite core and its rim, and/or between a colorless salite mantle and its rim. Dissolution surfaces are observed on all textural variants. Two magma chambers are needed to explain the observed clinopyroxene phenocrysts. A deep chamber at about 120 km in the upper mantle in which diopside cores crystallized, and a shallow chamber at depths of less than 40 km in which diopside cores were resorbed and overgrown by salite rims or mantles. Magma mixing in the shallow chamber is responsible for the formation of dissolution surfaces between the diopside bands and the colorless salite mantles. The dissolution surfaces on the diopside cores formed in the shallow chamber as a result of pressure decrease. This magma evolution scenario is complicated by the occurrence of the crustal-origin green salite cores in diopsides. These green cores likely represent the relics of continental materials, which were captured in the deep chamber and partially re-melted. Our observations indicate that subducted continental materials were returned to the Earth’s surface as a result of magmatism. This study therefore provides direct evidence of a link between subducted continental materials (slab) and magmatism in this orogenic belt. © 2003 Elsevier Ltd. All rights reserved.

The dolomite-dissociation textures documented here in rocks from the Kokchetav ultrahigh-pressure massif suggest that the experimentally expected dolomite dissociation happened in the subducted slabs represented by these rocks. Two reactions, magnesite=C + MgO + O2, and majoritic garnet + MgO + H2O = garnet + clinochlore, recorded in carbonate inclusions and the host majoritic garnet are responsible for generation of graphite and clinochlore during the exhumation. The dolomite dissociation indicates that carbonate materials were subducted to depths of .250 km below Earth’s surface. Such deep subduction evidently brings abundant carbon and carbonate into deep Earth.

The Wangfeng–Tianger–Saridala ore district consists of over 20 orebodies with total proven gold reserves exceeding 15 tonnes. The district is located on the EW-striking Tianger (Bingdaban) shear zone in west Tianshan Mountains, northwest China. The lensoid orebodies are distributed along the shear zone in a region about 25 km in length and 1 km in width. Enhanced fluid flow and fracturing controlled location and orientation of mineralized zones during deformation along narrow shear bands oriented oblique to the overall shear zone margins. Fabrics in fractures and strain shadow overgrowths generally plunge steeply, parallel to the lineation in the surrounding cataclasite matrix consisting of new grains of quartz and minor amounts of micas. Native gold occurs inmylonitized granites ormylonitized sulfide–mica–quartz veins.Gold grade is closely relatedwith the occurrence of sulfide–quartz veins. Pyrite and pyrrhotite in gold-bearing sulfide–quartz veins contain inclusions of native gold. Chondrite-normalized rare earth element (REE) distribution patterns for pyrite from the orebodies show light REE enrichments and negative Eu anomalies. Relationships between gold contents and Th/U, Zr/Hf and (La/Yb)N values for pyrites imply that gold-rich pyrites are different from goldpoor pyrites, thus indicate that the pyrites in the orebodies have a different origin compared with those in wall rocks. A Rb–Sr isochron for the mylonitized Au-bearing quartz veins indicates an age of 224±14 Ma with an initial 87Sr/86Sr ratio of 0.7294±0.0089 (MSWD=1.1). This age is conformed by 40Ar/39Ar dating on muscovites (220.9 to 222.5Ma), which is interpreted as the age of ore-formation in the Tianger deposit. High initial 87Sr/86Sr ratios (0.7294), high δ34S values (+11.2 to +16.5‰), low δ18OH2O values (1.67 to 3.07‰) and low δD values (−84 to −104‰) indicate that the ore-forming fluid was unrelated to any magmatic process. © 2006 Elsevier B.V. All rights reserved.

Kokchetav ‘lamproite’ occurs in the east end of Kokchetav massif and consists of phenocryst (mainly clinopyroxene) and matrix (mainly feldspar). The compositions of clinopyroxene, magnetite and biotite phenocryst were determined using wavelength dispersive spectrometry on a JEOL Super-probe 8900 electron microprobe for the purpose of revealing the process of magma evolution. Analyses revealed a core-rim variation, which is consistent with three stages of magmatic evolution: Mg-rich clinopyroxene cores (diopside) and biotite cores (phlogopite) crystallized in a deep magma chamber (stage I); Fe-rich clinopyroxene rim (salite) and biotite rim crystallized at low pressure in a shallow magma chamber (stage II); Magnetite phenocryst core also crystallized in a shallow magma chamber, and coexists with Fe-rich clinopyroxene rim and biotite rim. The magnetite rims probably formed during magma eruption at the same time when groundmass crystallized (stage III).The calculated temperatures for ilmenite-magnetite pair range from 679 to 887ºC, log fO2 values range from 311.1 to 314.9 log units. These values represent the latest conditions of magma as ilmenite exsolution in magnetite probably occurred during magma eruption from the shallow chamber to surface. © 2002 Elsevier Science B. V. All rights reserved.

Gold deposits in the Taihang Mountains, northern China, mainly consist of quartz sulfide veins in granitoid plutons. This paper describes the geological setting of the gold deposits, and presents the results of microthermometric, Fourier transform infrared spectra, and stable isotope analyses of ore-forming fluids for the purpose of examining the characteristics of these fluids. The ore-forming fluid was of high temperature (up to 380ºC) and high salinity (33–41 wt% NaCl equiv.), represented by type I inclusions (with daughter minerals). This fluid evolved to low salinity at low temperatures recorded in type II (liquid-rich) and III inclusions (vapor-rich). Primary type II inclusions coexist with type III inclusions in quartz. Type III inclusions have almost the same homogenization temperatures as type II inclusions. This probably reflects boiling. The secondary fluid inclusions homogenized at lower temperatures, and have lower salinities than primary inclusions. Based on microthermometric data, we propose that the high-temperature fluid that separated from residual magma corresponded to the ore-forming fluid represented by type I inclusions. This fluid mixed with meteoric water in the upper part of the granitic pluton and was diluted. The diluted fluid boiled, probably due to abrupt pressure decrease, and formed liquid-rich type II inclusions and vapor-rich type III inclusions. The deposition of sulfide minerals and gold probably occurred during boiling.

克拉玛依市西盆山交界处发育侏罗纪杏仁玄武岩-橄榄玄武岩F含菱铁矿橄榄玄武岩组合，主要由橄榄石、单斜辉石、斜长石(中长石-拉长石为主)、钛铁矿、玄武玻璃及少量磷灰石组成，含菱铁矿橄榄玄武岩中存在原生菱铁矿(≈10%)和少量碱性长石。橄榄石及单斜辉石的Mg#为≈70，单斜辉石属于富Ti普通辉石。含菱铁矿橄榄玄武岩中的菱铁矿常常包裹浑圆状斜长石，且与斜长石呈锯齿状接触。本文提供的岩相学观察表明，菱铁矿与玄武玻璃、斜长石、单斜辉石和钛铁矿呈明显的共生关系。在有些情况下观察到玄武玻璃与菱铁矿充填在斜长石格架的现象。含菱铁矿橄榄玄武岩玻璃中FeO含量最高至29.2%, CaO含量<1.5%，即熔体具有富Fe贫Ca的特点。早结晶的碳酸盐矿物是以菱铁矿为主的菱铁矿-白云石固溶体(另含少量菱锰矿)。斜长石大量结晶促使熔体不断亏损CaO，并导致较晚结晶的碳酸盐矿物向菱铁矿端元演化。菱铁矿发育有明显的成分梯变带(FeO和CaO含量表现出突变)。玄武玻璃的普遍Mg#较低且变化范围大，橄榄玄武岩中玻璃的Mg#值最高为64，含菱铁矿橄榄玄武岩中玻璃的Mg#值最低至～23。依据地质温压计，克拉玛依侏罗纪玄武岩浆的形成温度为1300ºC～1340ºC，压力为3.0～4.0CPa。基于本文的研究，我们认为克玛依侏罗纪含菱铁矿橄榄玄武岩岩浆由含CO2橄榄岩在软流圈中经极低程度部分熔融形成，该岩浆在快速上升过程中通过结晶分异作用形成了菱铁矿。

笔者初步总结了中亚主要成矿带的基本特征，并探讨了新疆邻区矿带在新疆境内的可能延伸。研究者对新疆邻区成矿带的划分、成矿建造类型和特征的认识不断在变化，因此，笔者强调，在与邻区地质矿产对比时，必须系统了解其研究历史并力求在查明控矿基本要素的基础上进行。此外，在中亚地区，与早古生代陆壳增生相关的成矿作用相当重要，而晚古生代的大规模成矿更多地表现为对已有成矿物质的继承、改造和新成矿物质的叠加，形成了多阶段成矿作用的复合，这些都属于中亚成矿域的特征，也是在对比研究中必须予以充分考虑的。通过分析和对比研究，故认为在中亚成矿域中控制大型、超大型矿床的主要成矿环境可初步概括为以下6种: (1)夹杂于显生宙造山带中的众多前寒武纪地块，在其内部形成了重要的原生铀矿和稀有金属矿床；(2)形成于早古生代陆缘增生带、成矿时代为加里东晚期的科克切塔夫东缘和北准噶尔(境外)的别斯图贝、玛依卡因、捷克利等重要的金、铜多金属矿床；(3)在加里东和前加里东陆壳围限的环巴尔喀什湖地区，具有多个峰期和在空间上相互叠加或有一定迁移规律的成矿作用；(4)境外中天山地块南部存在一条重要的成矿带，代表性的矿种是Au-Cu-Mo-W，该成矿带线性特征明显并与一个活动延续的时间长达70 Ma的巨型水热系统相关；(5)南哈萨克斯坦及其以南地区，中、新生代盆地中的可地浸型铀矿及晚古生代超大型砂岩铜矿等大都形成于碰撞后的陆内环境，其成矿作用还可能与深部来源的成矿物质有关；(6)中亚的重要矿床大都产在有所谓大型“横向构造”与成矿带交叉的部位，造成呈串珠状分布的矿结。

克拉玛依西山的枕状玄武岩与浊积岩-凝灰岩共生，厚度大于400米的枕状玄武岩层被火山角砾岩-安山岩-硅质岩-凝灰岩覆盖，岩枕之间充填着硅质泥岩。锆石SHRIMP定年结果表明，枕状玄武岩可能在早寒武世形成(>517Ma，这套地层曾经一直被认为属于石炭系)。枕状玄武岩的稀土元素含量(117.4～153.6 ppm)和配分模式与洋岛玄武岩(OIB)基本一致。枕状玄武岩中大离子亲石元素(Cs, Rb, Ba K, Pb和Sr)的含量变化较大(明显偏离OIB)，高场强元素(Nb, Ta, Zr, Hf, Ti和P)相对OIB和原始地幔没有表现出明显异常[e, g., (Nb/Ta)PM= 0.92～0.98, (Zr/Hf)PM=1.08～1.18]。西准噶尔地区存在这套OIB型海相火山-沉积建造说明古亚洲洋在西准噶尔地区于寒武纪就已经存在。这套海相玄武岩岩枕中存在大量古元古代-新太古代(1883～2536Ma)岩浆锆石的事实说明，早古生代洋岛玄武岩岩浆源区存在古老大陆地壳物质。