岩石学报  2016, Vol. 32 Issue (6): 1731-1748   PDF    
茫崖二长花岗岩、石英闪长岩的年代学、地球化学及岩石成因:对阿尔金南缘早古生代构造-岩浆演化的启示
康磊, 校培喜, 高晓峰, 奚仁刚, 杨再朝    
国土资源部岩浆作用成矿与找矿重点实验室, 中国地质调查局西安地质调查中心, 西安 710054
摘要: 阿尔金南缘茫崖地区出露着早古生代二长花岗岩体和石英闪长岩体,测得其LA-ICP-MS锆石U-Pb年龄为472.1±1.1Ma和458.3±6.2Ma。地球化学特征显示,前者属于钾玄质过铝质S型花岗岩,具高的(La/Yb)N和Sr/Y比值,低的HREE、Yb和Y值;后者为高钾钙碱性准铝质-过铝质I型花岗岩,具低的(La/Yb)N和Sr/Y值,高的Yb和Y含量。通过岩石成因和构造背景分析,二长花岗岩是陆壳深俯冲作用下,上地壳沉积岩(杂砂岩和少量泥质岩)被俯冲带入到50~80km深处,在高压(>1.5GPa)低温(779.8~792.9℃)条件下主要由云母分解脱水而发生部分熔融,残留相为石榴石+金红石(无角闪石),在岩浆演化过程中发生了以斜长石为主(无角闪石)的强烈分离结晶作用;石英闪长岩是在陆壳深俯冲后的折返抬升作用下,上地壳变质玄武岩被抬升至<30km处,在低压(>0.8GPa)高温(811.0~821.0℃)条件下发生部分熔融,残留相为角闪石+斜长石(无石榴石),在岩浆演化过程中发生了以辉石、金红石和磷灰石为主(无角闪石和斜长石)的分离结晶作用。结合前人研究成果,分析了阿尔金南缘早古生代岩浆活动特征及其形成机制,将该地区早古生代构造-岩浆演化分为三个阶段:1)505~472Ma陆-陆碰撞阶段,以高压环境下岩浆活动为特征,在陆壳深俯冲的同时,存在俯冲陆壳的初步熔融拆离作用;2)467~450Ma板片拆离阶段,由于俯冲板片的完全断离,强大的浮力主要使上地壳发生抬升折返,以低压高温环境下上地壳岩浆活动为特征,同时存在幔源岩浆的底垫作用,具同折返双峰式岩浆活动的特征;3)424~385.2Ma后碰撞伸展拉张阶段,持续的应力释放松弛使构造应力从前期的垂向抬升转换为侧向伸展,存在地幔岩浆的底侵上涌作用,以低压高温环境下A型花岗岩岩浆活动为特征。
关键词: 二长花岗岩和石英闪长岩     年代学     岩石成因     构造-岩浆演化     茫崖     阿尔金南缘    
Chronology, geochemistry and petrogenesis of monzonitic granite and quartz diorite in Mangai area: Its inspiration to Early Paleozoic tectonic-magmatic evolution of the southern Altyn Tagh
KANG Lei, XIAO PeiXi, GAO XiaoFeng, XI RenGang, YANG ZaiChao    
Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, MLR, Xi'an Center of Geological Survey, CGS, Xi'an 710054, China
Abstract: Early Paleozoic monzonitic granite and quartz diorite, outcropped in Mangai area of the southern Altyn Tagh, its' ages are each 322.8±2.2Ma and 319±1.7Ma with the method of LA-ICP-MS zircon U-Pb dating. According to geochemical data, the former is ascribed to shoshonitic with peraluminous S-type granite which be characterized by high (La/Yb)N and Sr/Y and low contents of HREE, Yb and Y, and the latter is ascribed to high K calc-alkaline series with metaluminous to slightly peraluminous I-type granite which has the characteristic of low (La/Yb)N and Sr/Y and high contents of HREE, Yb and Y. Moreover, in view of its' petrogenesis and tectonic setting, we considered that monzonitic granite in Mangai area was most likely derived from upper crust (sandstone and a little mudstones) which had be subducted into 50~80km depth, and partial melted on the environment of high pressure (>1.5GPa) and low temperature (779.8~792.9℃) by the dehydration from biotite with the residual mineral of garnet+rutile (without amphibole), and subsequently underwent the fractional crystallizatiion of plagioclase, meanwhile quartz diorite in Mangai area should be likely derived from metabasalt in upper crust which had be lifted to < 30km depth, and partial melted on the environment of low pressure (< 0.8GPa) and high temperature (811.0~821.0℃) with the residual mineral of amphibole+plagioclase (without garnet) during the stage of crustal uplifting after continent-continent collision, and subsequently underwent the fractional crystallizatiion of pyroxene, rutile and apatite (without amphibole and plagioclase). Consequently, we consider that Early Paleozoic tectonic-magmatic evolution of southern Altyn Tagh should be subdivided into three stages: 1) 505~472Ma, the dominating event during the period of continent-continent collision was continental crust deep subduction which was characterized by high pressure magma, with the slab breaking; 2) 467~450Ma, break-off of deep subducted continental slab caused strong buoyancy, which mainly leaded to exhumation and lifting of the upper crust, and magmatic activity on the environment of high temperature and low pressure displays characteristics of syn-exhumation magmatism with mantle magma underplating; 3) 424~385.2Ma, tectonic stress had transformed from vertical uplifting to lateral extending in the stage of the post-collisional extension, meanwhile magma was characterized by A-stye granitic magma on high temperature and low pressure which be relative to mantle magma upwelling.
Key words: Monzonitic granite and quartz diorite     Chronology     Petrogenesis     Tectonic-magmatic evolution     Mangai     Southern Altyn Tagh    
1 引言

近些年来,在阿尔金南缘的江尕勒萨依、淡水泉和英格利萨依等地陆续发现了代表陆壳深俯冲的多种高压-超高压变质岩石(Liu et al.,2002200420052007; 校培喜等,2001; Zhang et al.,200120022004; Zhang and Meng,2005),并确定阿尔金南缘是一条在早古生代经历过陆壳俯冲碰撞而形成的高压-超高压变质岩带。目前,已在阿尔金南缘陆壳俯冲深度、俯冲/折返峰期及其变质演化等研究方面已取得较大进展(Liu et al.,200220042005200720092012; 刘良等,2007; Wang et al.,2011; Zhang et al.,20012002; Zhang and Meng,2005; 曹玉亭等,2009; 刘良等,19992007; 张建新等,2001),研究表明该地区经历了以超高压岩石475~504Ma的峰期变质为代表的陆壳深俯冲作用和以高压麻粒岩相455Ma的退变质为代表的抬升折返作用(Liu et al.,20092012),然而通过对高压-超高压岩石的锆石U-Pb定年所确定的陆壳深俯冲和抬升折返作用的时代仅能代表其峰期,而且关于475~455Ma大陆深俯冲的结束时限(即:抬升折返的开始时限)以及大陆深俯冲作用与抬升折返作用之间的转换机制仍不明晰。

阿尔金南缘发育着大规模与深俯冲作用有关的花岗岩体(曹玉亭等,2010; 孙吉明等,2012; 杨文强等,2012; 康磊等,2013),对其岩浆作用时限、物源性质、部分熔融条件及其形成机制的研究,无疑对全面理解该地区大陆深俯冲、壳-幔相互作用、造山带及大陆地壳演化等地球动力学过程具有重要的科学意义。近些年,学者对该地区部分早古生代花岗岩体进行了研究(吴锁平等,2007; 王超等,2008; 曹玉亭等,2010; 孙吉明等,2012; 杨文强等,2012; 康磊等,2013; 吴才来等,2014; Kang et al.,20142015),并将花岗质岩浆活动主要分为3期:1)500Ma(陆-陆碰撞造山作用阶段地壳加厚阶段);2)462~451Ma(深俯冲陆壳发生断离后的伸展阶段);3)424~385Ma(造山期后的伸展阶段)(杨文强等,2012)。但是,以上研究均集中在阿尔金南缘的中西部,对其他地区的研究相对薄弱。最近1:25万区域地质调查(中国地质调查局西安地质调查中心,2013)在阿尔金南缘东部的茫崖地区厘定出大量早古生代花岗岩体,为进一步研究阿尔金早古生代构造演化过程提供了载体。本文通过对其中的二长花岗岩体和石英闪长岩体的岩石学、岩石地球化学、锆石U-Pb定年和Hf同位素研究,表明该地区472.1Ma时发育在高压低温的埃达克质岩浆活动,反映阿尔金南缘早奥陶世晚期仍处于陆-陆碰撞的深俯冲阶段,458.3Ma发育低压高温的岩浆活动,说明晚奥陶世早期已进入深俯冲陆壳发生断离后的抬升折返阶段,该认识为阿尔金南缘早古生代大陆深俯冲和抬升折返作用时限提供了重要信息。在前述研究的基础上,结合前人对阿尔金南缘早古生代岩浆岩的研究成果,对阿尔金南缘早古生代岩浆活动期次、岩石成因和形成机制进行系统分析,探讨了该地区早古生代岩浆-构造演化过程,提出了各阶段构造演化框架模式。

中国地质调查局西安地质调查中心. 2013. 巴什库尔干幅、茫崖镇幅1:25万区域地质调查(修测)报告

2 地质背景及岩体特征

阿尔金造山带位于青藏高原北缘,介于塔里木板块及柴达木微板块之间(图 1a),是一个由不同时期、不同构造层次和不同构造环境形成地质体所组成的复合造山带,经历了太古代-古元古代陆核和结晶基底的形成、中元古代稳定大陆边缘沉积、新元古代末期-早古生代板块扩张、加里东期板块俯冲-碰撞、晚古生代剥露夷平和局部浅海沉积、印支期的伸展作用和碱性岩侵位、晚燕山期大规模的左行走滑作用(Liu et al.,1997; 刘良等,1999; Yin et al.,2002; 许志琴等,1999; 周勇和潘裕生,1999)。从北至南划分为四个构造单元,依次为:阿北地块、红柳沟-拉配泉蛇绿构造混杂岩带、米兰河-金雁山地块、南阿尔金俯冲碰撞杂岩带(图 1b)(许志琴等,1999; 刘良等,1999; Zhang et al.,2001)。其中,南阿尔金俯冲碰撞杂岩带可进一步划分为南阿尔金高压-超高压变质带和南阿尔金蛇绿构造混杂岩带两部分(杨文强等,2012)。

图 1 茫崖地区中酸性侵入岩地质简图(b,据Wang et al.,2013; c,据中国地质调查局西安地质调查中心,2013) Fig. 1 Sketch geological map of intermediate acid intrusive rocks in Mangai area(b,modified after Wang et al.,2013)

在南阿尔金俯冲碰撞杂岩带南东部的茫崖地区发育着大规模奥陶纪-志留纪花岗岩体,分布于若羌县石棉矿-阿卡托山地区,由大小7个中酸性侵入体组成,其中奥陶纪花岗岩最为发育,主要岩石类型为灰白色二长花岗岩、灰白色石英闪长岩,主体多沿阿尔金断裂呈北东东向不规则带状展布,东北部侵入于古元古界达肯达坂岩群、寒武-奥陶系滩间山群,其他部位被早-中侏罗统大煤沟组、新近系油砂山组或第四系覆盖(图 1c),岩体中捕虏体不发育。本文对该地区出露面积最大的二长花岗岩体和石英闪长岩体进行了调查研究,具体采样位置见图 1c

灰白色二长花岗岩:块状构造,中细粒花岗结构,主要由碱性长石、斜长石、石英和黑云母组成。碱性长石呈自形-半自形板状,晶形为0.8×0.7~2.5×2.3mm,主要为条纹长石和微斜长石,分别具有明显的条纹结构和格子双晶(图 2a),含量为35%~42%;斜长石呈半自形-他形状,晶形为0.5×0.4~1.9×1.7mm,普遍发生了高岭石蚀变,含量为22%~30%;石英呈他形粒状、填隙状,粒径为0.4~1.7mm,含量为25%~35%;黑云母呈他形-半自形,晶形为0.05×0.07~0.4×0.5mm,一组极完全解理特征明显,含量为2%~5%;副矿物主要有榍石、锆石、磷灰石和磁铁矿等。

图 2 茫崖二长花岗岩和石英闪长岩的岩相学特征
(a)二长花岗岩的宏观岩石学特征;(b)石英闪长岩的宏观岩石学特征;(c)二长花岗岩的显微组构(正交偏光);(d)石英闪长岩的显微组构(正交偏光). 矿物代号:Q-石英;Pl-斜长石;Mi-微斜长石;Per-条纹长石;Am-角闪石;Bi-黑云母;Ttn-榍石
Fig. 2 The petrographical feature of monzonitic granite and quartz diorite in Mangai area
(a) macroscopic petrology feature of monzonitic granite; (b) macroscopic petrology feature of quartz diorite; (c) the microcosmic characters of monzonitic granite (orthogonal polarization); (d) the microcosmic characters of quartz diorite (orthogonal polarization). Q-quartz; Pl-plagioclase; Mi- microcline; Per-perthite; Am-amphibole; Bi-biotite; Ttn-titanite

灰白色石英闪长岩:块状、弱片麻状构造,中细粒结构,主要由斜长石、碱性长石、石英、角闪石、黑云母组成。斜长石为自形-半自形板粒状,晶形为0.5×0.8~3.0×3.4mm,普遍发生了高岭石和云母化蚀变,含量为40%~60%;碱性长石呈半自形-他形粒状,呈不规则板状,晶形为0.5×0.6~1×1.6mm,主要为微斜长石,格子双晶发育,含量为8%~15%;石英呈他形粒状、填隙状,粒径为0.2~1.9mm,含量为11%~17%;角闪石呈自形柱状,晶形为0.2×0.4~1.0×1.3mm,含量为3%~9%;黑云母呈半自形鳞片状,晶形为0.05×0.04~0.15×0.20mm,含量为3%~5%。此外,榍石呈自形楔状或板条状,粒径为0.2×0.4~1.2×1.6mm,含量为2%~4%;副矿物主要有锆石、磷灰石和磁铁矿等。

3 分析方法

除锆石由河北廊坊诚信地质服务有限公司挑选外,其它所有测试分析均在西北大学大陆动力学国家重点实验室完成。全岩主量元素分析在日本理学Rigaku RIX 2100型XRF仪上测定;全岩微量和稀土元素测试在美国Perkin Elmer公司Elan 6100 DRC型电感耦合等离子质谱(ICP-MS)仪上完成,样品测试中以AVG-1,BHVO-1和BCR-2标样监控;锆石的CL图像分析在装有英国Gatan公司生产的Mono CL3+阴极发光装置系统的电子显微扫描电镜上完成;锆石的微量元素分析和U-Pb年龄测定是在连接Geolas 2005紫外激光剥蚀系统(193nm深紫外ArF激光器)的Agilient 7500a型ICP-MS上进行的,激光剥蚀斑束直径为30μm,采样为单点剥蚀方式,以He作为剥蚀物质的载气,ICP-MS数据采集选用跳峰方式,数据处理采用Glitter(ver 4.0)程序,年龄计算以标准锆石91500为外标进行同位素比值分馏校正样品的谐和图和加权平均年龄计算及绘制均采用用Isoplot(ver2.49)(Ludwig,2003);锆石原位Lu-Hf同位素测定是在配备了Geolas 2005激光剥蚀系统的Nu Plasma HR(Wrexham,UK)多接收电感耦合等离子体质谱仪(MC-ICP-MS)上完成的,激光剥蚀的脉冲频率是10Hz,激光束斑直径为44μm,分析中利用锆石样品91500和GJ-1作外标,详细分析步骤和数据处理方法详见Yuan et al.(2008)

4 分析结果4.1 地球化学特征

主量和微量元素分析结果见表 1。主量元素分析结果表明,茫崖二长花岗岩具较高的SiO2含量(74.33%~76.52%),低的TiO2(0.11%~0.14%)、Fe2O3T(1.17%~1.26%)、MgO含量(0.24%~0.30%)和CaO(0.48%~0.96%),全碱含量较高(K2O+Na2O=8.28%~9.72%),相对富钾(K2O/Na2O=2.15~2.44)。茫崖石英闪长岩SiO2含量为61.29%~63.40%,具高的TiO2(0.62%~0.79%)、Al2O3(16.85%~18.40%)、Fe2O3T(4.80%~5.69%)、MgO(1.92%~2.41%)和CaO(2.51%~6.25%)含量,全碱含量中等(K2O+Na2O=6.15%~8.59%),略为富钠(K2O/Na2O=0.56~1.04)。在SiO2-氧化物的哈克图解中(图 3),茫崖二长花岗岩与石英闪长岩无明显一致的演化趋势,因此两者可能无成因联系。在SiO2-K2O图解中(图 4a),二长花岗岩位于钾玄质范围,石英闪长岩主要落于高钾钙碱性区域。二长花岗岩的A/CNK为1.02~1.06,石英闪长岩的A/CNK为0.80~1.10,在A/NK-A/CNK图解里二长花岗岩样品均落入过铝质范围,而石英闪长岩样品落入准铝质-过铝质(图 4b)。因此,茫崖二长花岗岩属于钾玄质过铝质系列,石英闪长岩则属于高钾钙碱性准铝质-过铝质系列。

表 1 茫崖二长花岗岩和石英闪长岩的主量元素(wt%)、稀土元素和微量元素(×10-6)含量 Table 1 Major element (wt%) and trace element (×10-6) composition of monzonitic granite and quartz diorite in Mangai area

图 3 茫崖二长花岗岩和石英闪长岩的SiO2-氧化物及其参数的相关图解 Fig. 3 Plots of SiO2 vs. other oxides or parameters of monzonitic granite and quartz diorite in Mangai area

图 4 茫崖二长花岗岩和石英闪长岩的K2O-SiO2(a,据Middlemost,1985)和A/NCK- A/NK(b,据Peccerillo and Taylor,1976)图解 Fig. 4 SiO2 vs. K2O diagram(a,after Middlemost,1985)and A/NCK vs. A/NK diagram(b,after Peccerillo and Taylor,1976)of monzonitic granite and quartz diorite in Mangai area

茫崖二长花岗岩和石英闪长岩的稀土元素总量较低(∑REE分别为156.5×10-6~235.1×10-6,188.8×10-6~253.1×10-6),轻重稀土分馏均明显((La/Yb)N分别为25.5~55.0,9.58~18.9),但二长花岗岩分馏程度明显较石英闪长岩强烈,且前者LREE相对HREE较后者富集(LREE/HREE分别为16.9~24.5,7.8~12.9),其中两者的轻稀土分馏程度均较高((La/Sm)N为6.58~7.26,3.69~5.78),而重稀土近于平坦((Gd/Yb)N为1.20~1.68,1.14~1.25)。在REE球粒陨石标准化模式图(图 5a)上,二长花岗岩和石英闪长岩样品的模式图均为右倾型,为较强的负铕异常(Eu/Eu*分别为0.56~0.66,0.67~0.77),但前者右倾程度明显较后者强烈,显示两者的稀土模式特征明显不同。在微量元素原始地幔标准化图上(图 5b),二长花岗岩和石英闪长岩的蛛网曲线特征相似,岩石均相对富集Rb、Th、U、K和LREE等大离子亲石元素,亏损Nb、Ta、P、Ti和HREE等高场强元素。

图 5 茫崖二长花岗岩和石英闪长岩的球粒陨石标准化稀土元素配分图(a)和原始地幔标准化微量元素蛛网图(b)(标准化值据Sun and McDonough,1989) Fig. 5 Chondrite-normalized REE-pattern(a)and primitive-mantle normalized spider diagram(b)of monzonitic granite and quartz diorite in Mangai area(normalization values after Sun and McDonough,1989)
4.2 LA-ICP-MS锆石U-Pb定年

茫崖二长花岗岩(11A07)和石英闪长岩(11A09)中锆石均呈自形或半自形的长-短柱状,但前者锆石形态明显较后者大,前者锆石晶体长0.03~0.3mm,宽0.02~0.15mm,柱状长宽比为1.2:1~3.5:1,后者锆石晶体长0.02~0.12mm,宽0.01~0.07mm,柱状长宽比为1.1:1~4:1。阴极发光图像中,除了11A07-12、11A09-1、11A09-(6、7)的环带不明显外,其他均表现出典型的岩浆震荡环带(图 6)。从2个样品的锆石微区同位素数据(表 2)可见,两者锆石的Th和U含量变化均较大(Th含量分别为42.77×10-6~1128×10-6、71.9×10-6~339.5×10-6,U含量分别为321.5×10-6~1265×10-6、140.4×10-6~897.7×10-6),且均具有较高的Th/U比值(0.25~1.27、0.29~0.84),这些特征与典型岩浆锆石特征一致(Claesson et al.,2000; 吴元保和郑永飞,2004)。

图 6 茫崖二长花岗岩11A07 (a)和石英闪长岩11A09 (b)中典型锆石CL图像及其年龄值和εHf(t)值
实心圆圈为代表年龄测点位置,虚线椭圆代表Hf同位素测点位置
Fig. 6 Representative zircon CL images, ages and εHf(t) of monzonitic granite 11A07 (a) and quartz diorite 11A09 (b) in Mangai area
Solid circles show the local of zircon dating; broken ellipses show the local of zircon Hf isotopes test

表 2 茫崖二长花岗岩和石英闪长岩(样品11A07/11A09)的LA-ICP-MS锆石U-Pb同位素分析结果 Table 2 LA-ICP-MS isotopic analysis of monzonitic granite and quartz diorite in Mangai area(Sample 11A07,11A09)

本次工作对二长花岗岩样品(11A07)成功测定了22颗锆石,206Pb/238U年龄范围均集中在467~474.5Ma之间,最大的年龄误差为4.0Ma,其中10X07-09测点明显偏离谐和线(图 7a),这可能与锆石的Pb丢失有关,剩下的21个测点分布集中且谐和性较好,206Pb/238U加权平均年龄为472.1±1.1Ma,MSWD=0.23(95%置信度)(图 7a),代表了二长花岗岩体的结晶年龄。对石英闪长岩样品(11A09)仅测定了6颗锆石7个点,但各个测点均在谐和线附近,误差为2.7~11.4Ma,其中10X09-06、07两个测点206Pb/238U年龄表面年龄分别为2343.5±11.4Ma、2330.8±11.4Ma,明显偏离了206Pb/238U年龄的正常分布范围,且锆石形态相对较大,岩浆环带不发育,与其它锆石差异明显,可能代表继承锆石或捕获锆石的年龄。剩下的5颗锆石其206Pb/238U年龄均452.5~466.4Ma之间,构成年龄集中区,样品的加权平均206Pb/238U年龄为458.3±6.2Ma,MSWD=0.26(95%置信度)(图 7b),应代表石英闪长岩体的结晶年龄。

图 7 茫崖二长花岗岩11A07 (a)和石英闪长岩11A09 (b)的LA-ICP-MS锆石U-Pb年龄谐和图 Fig. 7 LA-ICP-MS zircon U-Pb concordia diagram of monzonitic granite 11A07 (a) and quartz diorite 11A09 (b) in Mangai area
4.3 锆石Hf同位素特征

本次工作对茫崖二长花岗岩(11A07)中18颗锆石进行了Hf同位素分析(表 3)。其中,176Lu/177Hf比值均小于0.002,表明锆石形成后放射性成因Hf积累很少,因此176Hf/177Hf比值基本上可以代表锆石结晶时体系的Hf同位素组成。本文采用Taylor and McLennan(1985)推荐的上壳平均成分(0.008)计算tDMcεHf(t)和tDMc采用各点U-Pb年龄计算。分析结果见表 3图 8a,其176Hf/177Hf=0.282420~0.282542,εHf(t)为-2.28~1.86,平均值为-0.0467,同时tDMc=1162~1371Ma,暗示该花岗岩的源岩主要来源于(中新元古界)地壳物质。

表 3 茫崖二长花岗岩(样品11A07)的锆石Hf同位素分析结果 Table 3 Zircon in situ Hf isotope analysis data of monzonitic granite (Sample 11A07) in Mangai area

图 8 茫崖二长花岗岩的εHf(t)-t图解(a)和二长花岗岩、石英闪长岩A/FM-C/FM图解(b)(据Altherr et al.,2000) Fig. 8 εHf(t)-t diagram of monzonitic granite(a)and A/FM-C/FM diagram of monzonitic granite and quartz diorite(b)(after Altherr et al.,2000)in Mangai area
5 讨论5.1 茫崖二长花岗岩的成因

茫崖二长花岗岩TiO2、Fe2O3T、MgO、CaO与SiO2无负相关性(图 3),说明岩浆演化过程中以角闪石为主的铁镁矿物的分离结晶作用不明显,这与岩石中不发育角闪石以及黑云母结晶程度较低(他形-半自形)一致。岩石Al2O3、Eu与SiO2均呈明显的负相关性(图 3bg),以及在微量元素蛛网图中Sr、Ba和Eu均呈负异常,说明在岩浆演化过程中发生了强烈的斜长石分离结晶作用。

茫崖二长花岗岩主要由碱性长石、斜长石、石英和黑云母组成,不发育角闪石,具高SiO2、碱度和K2O,低TiO2、Fe2O3T、MgO和CaO,为弱过铝质钾玄质系列,显示S型花岗岩的矿物组合和岩石化学特征(Whalen et al.,1987; Ghani et al.,2013)。实验岩石学资料表明,在准铝质到弱过铝质岩浆分异过程中,磷灰石的溶解度较低,随SiO2的增加而降低,而在强过铝质岩浆中,磷灰石溶解度变化趋势与此相反(Wolf and London,1994)。磷灰石在I型和S型花岗岩浆中这种不同行为已被成功地用于区分I型和S型花岗岩类(Chappell,1999)。茫崖二长花岗岩SiO2与P2O5呈正相关性(图 3f),与S型花岗岩演化趋势一致,且SiO2与Yb也呈正相关性(图 3h),说明随着岩浆演化,磷灰石溶解度的提高对Yb含量增高也起到一定作用。茫崖二长花岗岩Al2O3=12.64%~13.80%,A/CNK=1.02~1.06,CIPW标准矿物中刚玉分子含量为0.3%~0.9%,相对典型S型花岗岩A/NKC值大于1.1,刚玉分子含量大于1%(Chappell and White,2001)略低,这应与岩浆演化过程中发生了强烈的斜长石分离结晶作用有关。以上特征,说明二长花岗岩的早期岩浆应具强过铝质的特征。

已有研究表明,与造山带碰撞有关的强过铝质花岗岩的源区具有多样性(Johannes and Holtz,1996; Winther,1996)。茫崖二长花岗岩相对富集Rb、Ba、Th、U、K和LREE等大离子亲石元素,亏损Nb、Ta、P、Ti和HREE等高场强元素(图 5b),低的Mg#值(Mg#=0.14~0.18),高的Th/U值(Th/U=14.19~15.78),以及Zr/Hf比值(Zr/Hf=33.23~34.24)接近于上地壳(Rudnick and Gao,2003),暗示源岩应来自上地壳。实验岩石学表明,CaO/Na2O的比值可推断中酸性岩浆的源区特征。对于过铝质花岗岩,熔融实验表明控制其CaO/Na2O比值的主要因素是源区长石/黏土的比(Sylvester,1998)。其中贫长石、富黏土的泥岩熔融生成的过铝质花岗岩所含的CaO/Na2O比值一般< 0.3,而富长石、贫黏土的砂屑岩生成的过铝质花岗岩的CaO/Na2O比值一般>0.3。茫崖二长花岗岩CaO/Na2O大多>0.3(0.34~0.35),只有样品(11A-07/2)CaO/Na2O为0.17,指示源岩应以砂屑岩为主,夹杂少量泥岩。在A/MF-C/MF图解中(图 8b),茫崖二长花岗岩样品大多落入杂砂岩部分熔融范围,个别位于泥质岩部分熔融区域,进一步印证了这一点。

锆石饱和温度计采用Watson and Harrison(19832005)从高温实验(700~1300℃)得出的锆石溶解度的模拟公式:TZr(℃)={12900[lnDZr(496000/熔体)+0.85M+2195]}-273.15,式中DZr为Zr分配系数,茫崖二长花岗岩样品的M值范围为1.32~1.40,在推荐范围之内(0.9~1.7,Watson and Harrison,1983)。计算表明,茫崖二长花岗岩的锆石温度为779.8~792.9℃,且样品中个别锆石发育残留核(11A07-2、7、22)(图 6a),说明母岩浆中锆石已达饱和,因此779.8~792.9℃可代表原始岩浆的初始岩浆温度(Miller et al.,2003; 赵振华,2010)。此外,在指示Fe-Ti氧化物等温线的SiO2-TiO2关系图中(图 3a),岩浆温度远低于900℃,以及在SiO2-P2O5温度关系图中(图 3i),指示岩浆温度略低于800℃,与锆石饱和温度计算结果一致。岩石学研究表明,地壳低温(<; 800℃)部分熔融产生岩浆时,需要源区有一定量水的加入(Clemens and Watkins,2001; Best and Christiansen,2001),岩浆源区中水可以来自于黑云母、白云母和角闪石等含水矿物的脱水反应(Vielzeuf and Montel,1994; Best and Christiansen,2001)。茫崖二长花岗岩具有SiO2含量高(平均74.92%),富铝(A12O3平均13.43%)和富钾(K2O平均6.42%),高碱含量(ALK平均9.16%),过铝质(A/CNK平均1.04)和非常低的Fe2O3T+MgO+TiO2含量(平均1.62%),因此暗示其可能主要由云母分解脱水而引发的部分熔融的产物(Patiño Douce,2005)。

茫崖二长花岗岩具有高的(La/Yb)N(25.5~55.0,平均值为45.7)和Sr/Y值(19.6~33.8,平均值为27.1),低的HREE(15.74~20.05,平均值为17.48)、Yb(0.73~1.07,平均值为0.83)和Y值(7.42~11.31,平均值为8.73)。而且,Sr/Y与SiO2呈非正相关性(图 3i),Yb与SiO2呈非负相关性(图 3h),排除了其地球化学特征为岩浆分异成因的可能,后者则指示岩浆演化过程中可能无富集HREE和Yb元素的矿物分离结晶,而样品HREE亏损,以及Yb和Y含量较低,说明岩浆源区应有石榴石残留,且(La/Yb)N与(Dy/Yb)N和(La/Yb)N与Nb/Ta图解(图 9ab)进一步说明岩石的稀土元素分异程度主要受残留石榴石比率所控制(He et al.,2011; 李曙光等,2013)。二长花岗岩TiO2与SiO2无负相关性(图 3a),说明在岩浆演化过程中无富TiO2矿物(金红石、榍石等)的分离结晶作用,而微量元素蛛网图中存在Ti的亏损(图 5b)则暗示源区可能有金红石残留,同时Nb/Ta值随(La/Yb)N值增高略有升高(9b)也指示了源区残留石榴子石的同时还应存在少量金红石,加之(La/Yb)N与Nb/La呈曲线负相关性(图 9c),这与熔体随着残留石榴子石和金红石的增加元素变化的趋势完全一致(熊小林等,2011)。此外,角闪石强烈富集MREE,而二长花岗岩HoN>YbN说明角闪石可能已发生分解无残留(李承东等,2004)。因此,茫崖二长花岗岩源岩部分熔融的残留相应为石榴石+金红石(无角闪石),说明部分熔融时压力较大,应>1.5GPa(Xiong et al.,2006; 张旗等,2006)。

5.2 茫崖石英闪长岩的成因

茫崖石英闪长岩主要由斜长石、碱性长石、石英、角闪石和黑云母组成,特别是富含榍石(2%~4%),岩石具低SiO2,高TiO2、Fe2O3T、MgO和CaO含量,以及高Na2O(3.95%~4.34%),均大于3.2%,为准铝质-过铝质高钾钙碱性系列,这与I型花岗岩的矿物组合和岩石化学特征一致(Ghani et al.,2013)。而且,SiO2与P2O5呈负相关性(图 3f),与I型花岗岩演化趋势相同(Chappell,1999; Ghani et al.,2013)。

茫崖石英闪长岩的Fe2O3T、MgO、CaO与SiO2的含量呈明显的负相关(图 3),指示岩浆演化过程中可能发生了辉石、角闪石等铁镁矿物的分离结晶。对于角闪石来说,Yb具有比Y更高的分配系数,角闪石的分离结晶就会导致熔体中Y/Yb的升高,而样品的Y/Yb基本无变化(11.2~11.7),因此排除了角闪石发生分离结晶的可能。样品的TiO2含量较高,而且岩石中富Ti矿物榍石发育,说明在岩浆过程中岩浆Ti为饱和状态,TiO2与SiO2呈负相关性(图 3a),并且(La/Yb)N与(Dy/Yb)N和(La/Yb)N与Nb/Ta图解(图 9ab)均与熔体随金红石结晶分异变化趋势一致,说明岩浆演化过程中应存在金红石的结晶分异作用。此外,P2O5与SiO2含量呈负相关关系(图 3f),并在微量元素蛛网图中具明显的P负异常(图 5b),说明也存在大量磷灰石的结晶分异作用。但是,Al2O3和Eu元素均与SiO2明显无相关性(图 3b),表明岩浆演化过程中斜长石的分离结晶作用不明显,这与石英闪长岩中斜长石含量较高(40%~60%)的矿物学特征一致。因此,茫崖石英闪长岩在岩浆演化过程中发生了以辉石、金红石和磷灰石为主的分离结晶作用,而角闪石和斜长石基本未发生分离结晶。

茫崖石英闪长岩相对富集Rb、Ba、Th、U、K和LREE等大离子亲石元素,亏损Nb、Ta、P、Ti和HREE等高场强元素(图 5b),并具低的Mg#值(Mg#=0.25~0.27),高的Th/U值(Th/U=6.7~8.9),显示岩体的岩浆主要来自地壳。样品Nb/Ta=11.54~14.20,接近上地壳平均值(图 9b)(Rudnick and Gao,2003),Zr/Hf比值为43.3~45.4,略高于上地壳的Zr/Hf比值(≈37,Gao et al.,1998),而且石英闪长岩的REE配分模式以及微量元素蛛网图均与上地壳平均组成基本一致(图 5),这些特征指示其源岩应来自上地壳。实验岩石学表明,当CaO/Na2O < 0.5时暗示源区为泥质岩,当CaO/Na2O比值介于0.3~1.5之间时中酸性的花岗质岩石则源于变杂砂岩或火成岩,而且角闪岩部分熔融而成的偏中性熔体(花岗闪长岩、闪长岩等)会具有略高的CaO/Na2O比值(Jung and Pfänder,2007)。茫崖石英闪长岩的CaO/Na2O比值较高,介于0.60~1.57之间(平均值为1.04),与变砂岩或火成岩源区一致。结合CaO/(MgO+FeOT)-Al2O3/(MgO+FeOT)的源岩判别图(图 8b),样品均位于变质玄武岩部分熔融区域,因此茫崖石英闪长岩的源岩应为上地壳变质玄武岩。

指示Fe-Ti氧化物等温线的SiO2-TiO2关系图,表明茫崖石英闪长岩的岩浆温度应低于900℃(图 3a),而SiO2-P2O5温度关系图则指示岩浆温度应高于800℃(图 3i)。同时,锆石饱和温度计计算表明,石英闪长岩除了11A-09/3样品的M值(2.17)大于推荐值0.9~1.7(Watson and Harrison,1983)外,其他样品的M值为1.52~1.70,均在推荐值范围内,这些样品的锆石温度为811.0~821.0℃,且样品中存在继承锆石或捕获锆石(11A09-6、7)(图 6b),说明母岩浆中锆石已达饱和,因此811.0~821.0℃可代表原始岩浆的初始岩浆温度(Miller et al.,2003; 赵振华,2010),表明其初始岩浆温度较高,这与岩石的TiO2含量(平均值为0.73)较高吻合。

茫崖石英闪长岩的(La/Yb)N(9.58~18.9,平均值为15.6)和Sr/Y值(12.2~21.5,平均值为17.9)较低,Sr(405~527,平均值为486)、Yb(4.2~5.7,平均值为4.9)和Y含量(23.4~33.2,平均值为27.8)均较高,并且(La/Yb)N与(Dy/Yb)N和(La/Yb)N与Nb/Ta均呈非正相关性(图 9a,b),以上特征均指示其源岩部分熔融的残留体中应不存在石榴子石(He et al.,2011; 李曙光等,2013)。茫崖石英闪长岩在岩浆演化过程中不存在角闪石和斜长石的分离结晶作用(前文已论述),而(La/Yb)N与(Dy/Yb)N呈负相关性(图 9a),并且Eu和Sr均具负异常,这些特征分别指示岩石部分熔融时可能存在角闪石和斜长石的残留(无石榴石)。岩石学熔融实验表明,玄武岩部分熔融时熔体与斜长石和角闪石处于平衡时,压力应< 0.8GPa(吴福元等,2002; 葛小月等,2002)。

图 9 茫崖二长花岗岩和石英闪长岩的(Dy/Yb)N-(La/Yb)N(a)、Nb/Ta-(Dy/Yb)N(b)图解(据He et al.,2011)和Nb/La-(La/Yb)N图解(c,据熊小林等,2011)图(b)中的UCC,BCC,LCC分别代表大陆上地壳、大陆地壳总体和大陆下地壳 Fig. 9 (Dy/Yb)N-(La/Yb)N(a),Nb/Ta-(Dy/Yb)N(b)(after He et al.,2011)and Nb/La-(La /Yb)N(c,after Xiong et al.,2011)diagram of monzonitic granite and quartz diorite in Mangai areaUCC,BCC and LCC represent upper continent crust,bulk continent crust and Lower continent crust in Fig. 9b
5.3 茫崖二长花岗岩和石英闪长岩的成岩模式及构造背景

大量研究表明,增温、降压和加入富水流体是导致源岩发生部分熔融的主要因素(邓晋福等,2004; 桑隆康和马昌前,2012)。以上岩石成因研究表明,茫崖二长花岗岩的源岩部分熔融所需的少量水主要来自云母的分解脱水作用,并且在岩浆演化过程中,斜长石发生了分离结晶,但角闪石的分离结晶不明显,而岩浆只有在含水量较低时,才能使斜长石稳定存在,而抑制角闪石结晶的发生(Richards et al.,2001; Annen et al.,2006),说明源岩和形成的岩浆含水量较低,因此排除外来富水流体导致部分熔融的可能。依据源岩部分熔融时残留相为石榴石+金红石(无角闪石),指示其当时压力较高(>1.5GPa),也排除由降压导致部分熔融的可能性。但是,残留体中存在石榴石和金红石,而不存在角闪石,说明岩浆形成的地壳深度可达50~80km(Xiong,2006; 吴福元等,2007; 熊小林等,2011)。大量事实证明,大陆内部碰撞可使陆壳增厚到50km以上,由于大陆的地热梯度和加厚地壳所造成的放射成因热的加强,可造成其温度达1000℃(桑隆康和马昌前,2012),最终会导致部分熔融的发生。而且,地壳增厚造成温度升高的最佳效果取决于增厚的速率(桑隆康和马昌前,2012),茫崖二长花岗岩原始岩浆的初始温度仅为779.8~792.9℃,则说明地壳加厚的速率可能较快。目前,许多研究已表明阿尔金南缘以超高压岩石变质为代表的陆壳深俯冲作用峰期为486~504Ma(Liu et al.,2012; 刘良等,20072013),茫崖二长花岗岩形成时代为472.1Ma,说明在陆壳深俯冲作用峰期之后到472.1Ma,该地区仍存在地壳快速加厚作用,这明显与陆-陆碰撞伴随的陆壳深俯冲作用有关。这也得到了该地区超高压变质岩石的支持,Liu et al.(2009)曾得到阿尔金南缘清水泉地区榴辉岩的变质峰期年龄为475±4Ma,与茫崖二长花岗岩形成年龄基本一致,说明阿尔金南缘472Ma是可能存在陆壳深俯冲作用的。结合茫崖二长花岗岩的岩石成因特征,其应是在陆壳深俯冲作用下,上地壳沉积岩(杂砂岩和少量泥质岩)被俯冲带入地壳50~80km深处,由于强大的剪切作用和温度的剧增而发生部分熔融,所以推测早奥陶世晚期(472.1Ma)阿尔金南缘仍存在陆壳深俯冲作用,其时限应为472~504Ma。

通过岩石成因分析,表明茫崖石英闪长岩是上地壳变质玄武岩部分熔融的产物,残留体为角闪石+斜长石(无石榴石),说明当时岩浆活动压力较小(< 0.8GPa),指示岩浆形成的地壳深度大概应< 30km(张旗等,2006),明显较早期以二长花岗岩为代表的岩浆压强(>1.5GPa)降低,此外石英闪长岩原始岩浆的初始岩浆温度为811.0~821.0℃,属于高温花岗岩(Miller et al.,2003),说明茫崖石英闪长岩岩浆形成的主要因素应为降压和增温。茫崖石英闪长岩形成年龄为458.3±6.2Ma,滞后于陆壳深俯冲时限14Ma,并且与超高压的退变质年代455Ma基本一致,推测岩浆的形成可能与深俯冲陆壳折返抬升导致压力急剧降低有关。此外,与陆壳深俯冲有关的同折返岩浆活动,往往产生双峰式岩浆,即镁铁质岩+花岗岩(Davies and von Blanckenburg,1995; 李曙光等,1996; Sun et al.,2002),在阿尔金南缘长沙沟-清水泉地区发育形成于467.4Ma的大陆裂谷性质的镁铁质—超镁铁质岩体(马中平等,20092011),与区域上包括茫崖石英闪长岩的中晚奥陶世花岗岩共同组成双峰式岩浆岩,与同折返岩浆活动特征一致。而且,长沙沟-清水泉地区幔源镁铁质-超镁铁质岩石的存在,指示该地区深俯冲陆壳折返抬升的过程中地壳下部应存在幔源岩浆的底侵作用(邓晋福等,2004),这为中酸性岩浆的形成提供了热源。因此,茫崖石英闪长岩是在深俯冲陆壳折返抬升的构造背景下,压力急剧降低,并伴随着幔源岩浆的底侵作用提供了热源,最终导致上地壳变质玄武岩在低压高温条件下发生部分熔融。

5.4 阿尔金南缘早古生代岩浆-构造演化过程

目前,通过阿尔金南缘高压-超高压变质岩带的研究,揭示了南阿尔金构造带在早古生代主要经历了陆壳深俯冲及其后抬升折返的构造演化过程,在此过程中必然会伴随着幔源岩浆上涌、幔源岩浆与壳源岩浆发生混合作用或(和)大陆地壳的重熔等复杂的岩浆活动作用(Pitcher,1983; Miller et al.,1999)。阿尔金南缘发育着大量与陆壳深俯冲和抬升折返作用关系密切的岩浆岩,形成时代从中寒武世-中泥盆世(496.9~385.2Ma)均有发育,近几年较多学者对不同岩体进行了研究(表 4)(吴锁平等,2007; 王超等,2008; 曹玉亭等,2010; 孙吉明等,2012; 杨文强等,2012; 康磊等,2013; 吴才来等,2014; Kang et al.,20142015),但尚缺乏系统深入的研究(杨文强等,2012)。本文通过对茫崖二长花岗岩和石英闪长岩的分析,结合前人对阿尔金南缘其他早古生代岩体的研究,依据岩浆岩的形成时代、源岩特征和岩石成因,分析各阶段岩浆活动特征及其形成机制,进而将阿尔金南缘早古生代构造演化分为三个阶段,提出各阶段的构造演化模式图(图 10)。

表 4 阿尔金南缘早古生代岩浆岩主要特征表 Table 4 The main features of early Palaeozoic magmatite in South Altyn Tagh

图 10 阿尔金南缘早古生代构造演化模式图
(a)505~472Ma陆-陆碰撞阶段陆壳深俯冲;(b)467~450Ma板片拆离阶段抬升折返;(c)424~385Ma后碰撞阶段伸展拉张. 图(a)和(b)据Davies and Blanckenburg(1995)Li et al.(20132014)和Burov et al.(2014)修改
Fig. 10 Early Palaeozoic tectonic evolution pattern of southern Altyn Tagh
(a)505~472Ma deep subduction of continental crust during the stage of continental collision;(b)467~450Ma exhumation during the stage of break-off of the Altyn deep subducted continantal slab;(c)424~385Ma extension during the stage of post-collisional. Fig. 10a,b are modified after Davies and Blanckenburg(1995)Li et al.(20132014)and Burov et al.(2014)

505~472Ma陆-陆碰撞阶段陆壳深俯冲(图 10a):该阶段发育规模较小的花岗岩侵入体,主要为长沙沟闪长岩(Kang et al.,2014)、鱼目泉岩浆混合花岗岩体(孙吉明等,2012)和茫崖二长花岗岩体(本文),形成时代分别为502Ma、496.9±1.9Ma、472.1±1.1Ma,与超高压岩石变质为代表的陆壳深俯冲作用峰期475~504Ma(Liu et al.,2012; 刘良等,20072013)基本相同,岩石具高(La/Yb)N、高Sr低Y的地球化学特征,以高压环境下岩浆活动为特征,为陆-陆碰撞造山作用阶段地壳加厚背景下的产物(孙吉明等,2012; Kang et al.,2014及本文)。以茫崖二长花岗岩为代表的上地壳沉积岩深俯冲,由于剪切作用和温度的增高而引发的岩浆作用。特别是,鱼目泉岩浆混合花岗岩体为代表的,其中发育代表壳幔岩浆混合作用的大量暗色幔源包体(孙吉明等,2012),指示在陆壳深俯冲阶段地幔岩浆与深俯冲陆壳存在强烈的相互作用,幔源岩浆的参与增高了会聚板块的温度场,促使俯冲陆壳发生弱化作用,导致俯冲陆壳发生初步的熔融拆离作用(Toussaint et al.,2004; Li et al.,20132014; Burov et al.,2014)。而且,该阶段岩浆岩均分布于阿尔金断裂南侧(图 1b),这与最近Li et al.(20112014)通过单向高角度大陆俯冲数值模拟得出陆壳深俯冲过程中部分熔融岩石均靠近缝合带左侧(即:深俯冲陆壳一侧)展布的特征完全一致。

467~450Ma板片拆离(slab break off)阶段抬升折返(图 10b):该阶段岩浆岩较为发育,岩体出露规模较大,阿尔金断裂南北两侧均有发育,主要岩石类型为钾长花岗岩、二长花岗岩、石英闪长岩和少量辉橄岩、角闪辉长岩,形成时代为467.4±1.4Ma、462±2Ma、458.3±6.2Ma、452.8±3.1Ma和451±1.7Ma(分别为马中平等,2011; 曹玉亭等,2010; 本文; 杨文强等,2012; 康磊等,2013),晚于陆-陆碰撞深俯冲时限,并与超高压的退变质年代455Ma基本同期。由于前期深俯冲的大陆地壳物质持续发生熔融弱化,直至467Ma俯冲板片发生完全拆离,以467.4Ma大陆裂谷构造背景下长沙沟-清水泉镁铁质-超镁铁质岩体的形成为标志(马中平等,20092011)。由于上地壳密度较小以及相对较易发生部分熔融,很难俯冲至较深部位,造成拆离的板片以镁铁质下地壳、岩石圈地幔和残留洋壳为主(Burov and Yamato,2008; Burov et al.,2014),俯冲板片断离之后,partial or complete loss of the slab pull force(Duretz et al.,2012)以及强大的浮力(Royden et al.,2008; Li et al.,20132014)使构造背景从深俯冲转换为抬升折返。构造模拟实验已证明,俯冲板片断离仅能使俯冲陆壳内部以长英质岩石为主的上地壳产生上浮力,而不能使镁铁质的下地壳岩石抬升折返(张宏飞等,2001; 李曙光,2004; 李曙光等,2005),因此造成阿尔金南缘该阶段发生以上地壳物质为主(沉积杂砂岩)的减压熔融作用(杨文强等,2012; 康磊等,2013及其本文)。而且,板片断离会导致热的软流圈岩浆在断离面处流动(Duretz et al.,2012; Li et al.,2013),长沙沟-清水泉镁铁质-超镁铁质岩体的发育,指示幔源岩浆底垫作用的存在,为上地壳物质部分熔融提供了热源(前文已论述),这与该阶段中酸性岩浆岩源岩高温(800℃)低压(< 0.8Gpa或< 1Gpa)的部分熔融特征(曹玉亭等,2010; 杨文强等,2012及其本文)一致,也与折返岩浆岩的岩石组合、源岩特征和形成机制吻合。

424~385.2Ma后碰撞阶段伸展拉张(图 10c):该阶段岩浆岩也较为发育,岩体规模较大,主要发育于阿尔金断裂南侧,岩石类型均为单一,以正长花岗岩为主,岩石具低Sr高Y和低的Sr/Y比值,均为典型A型岩浆岩,代表着伸展构造背景(吴锁平等,2007; 王超等,2008; 吴才来等,2014; Kang et al.,2015)。而且,玉苏普阿勒克塔格岩体中发育大量暗色幔源包体,是幔源岩浆与下地壳不断相互作用的结果,代表早古生代末期存在幔源岩浆的底侵上涌作用(王超等,2008),这为A型花岗岩的高温岩浆形成提供了热源。该阶段岩浆岩形成时代为424Ma(王超等,2008),404.2±4.6Ma、405.5±4.2Ma、411.2±5.4Ma、405.8±2.9Ma(吴才来等,2014)和385.2±8.1Ma(吴锁平等,2007),滞后于板片拆离阶段,应是经历了前阶段抬升折返后,由于持续的区域应力释放松弛,构造应力从垂向抬升转换为侧向伸展作用,424~385.2Ma进入了后碰撞伸展拉张阶段,同时由于幔源岩浆底侵作用的存在,从而形成低压高温环境,为A型花岗岩的形成提供了理想场所。

6 结论

(1)茫崖二长花岗岩形成年龄为472.1±1.1Ma,属于钾玄质过铝质S型花岗岩,(La/Yb)N和Sr/Y值较高,HREE、Yb和Y值较低;茫崖石英闪长岩形成年龄为458.3±6.2Ma,属于高钾钙碱性准铝质-过铝质I型花岗岩,(La/Yb)N和Sr/Y值较低,Yb和Y含量较高。

(2)茫崖二长花岗岩是陆壳深俯冲作用下,上地壳沉积岩(杂砂岩和少量泥质岩)被俯冲带入50~80km深处,在高压(>1.5GPa)低温(779.8~792.9℃)条件下主要由云母分解脱水而发生部分熔融,残留相为石榴石+金红石(无角闪石),在岩浆演化过程中发生了以斜长石为主(无角闪石)的强烈分离结晶作用而形成的产物;茫崖石英闪长岩是在陆壳深俯冲后的折返抬升作用下,上地壳变质玄武岩被抬升至<30km处,在低压(>0.8GPa)高温(811.0~821.0℃)条件下发生部分熔融,残留相为角闪石+斜长石(无石榴石),在岩浆演化过程中发生了以辉石、金红石和磷灰石为主(无角闪石和斜长石)的分离结晶作用而形成的产物。

(3)依据岩浆活动特征及其形成机制,将阿尔金南缘早古生代构造-岩浆演化分为三个阶段:①505~472Ma陆-陆碰撞阶段陆壳深俯冲:岩浆岩均具高(La/Yb)N、高Sr低Y的地球化学特征,以高压环境下岩浆活动为特征,为地壳深俯冲背景下的产物,并在陆-陆碰撞阶段陆壳深俯冲的同时,地壳与地幔发生强烈的相互作用,地幔岩浆已经开始对俯冲陆壳进行初步的熔融拆离;②467~450Ma板片拆离阶段抬升折返:俯冲板片完全断离,产生强大的浮力,使比重较小的上地壳(主要为沉积岩)发生抬升折返,主要使以沉积岩为主(少量变质玄武岩)的上地壳发生部分熔融,以低压高温环境下岩浆活动为特征,并存在幔源岩浆的地垫作用,为上地壳部分熔融提供了热源,具同折返双峰式岩浆活动的特征;③424~385.2Ma后碰撞阶段伸展拉张:由于持续的区域应力释放松弛,构造应力从垂向抬升转换为侧向伸展作用,岩浆岩具低Sr高Y和低的Sr/Y比值,均为典型A型花岗岩。

参考文献
[1] Altherr R, Holl A, Heger E, Langer C and Kreuzer H. 2000. High-potassium, calc-alkaline I-type plutonism in the European Variscides: Northern Vosges (France) and northern Schwarzwald (Germany). Lithos, 50(1-3): 51-73
[2] Annen C, Blundy JD and Sparks RSJ. 2006. The genesis of intermediate and silicic magmas in deep crustal hot zones. Journal of Petrology, 47(3): 505-539
[3] Best MG and Christiansen EH. 2001. Igneous Petrology. Oxford: Blackwell Science, 1-480
[4] Burov E and Yamato P. 2008. Continental plate collision, P-T-t-z conditions and unstable vs. stable plate dynamics: Insights from thermo-mechanical modelling. Lithos, 103(1-2): 178-204
[5] Burov E, Francois T, Yamato P and Wolf S. 2014. Mechanisms of continental subduction and exhumation of HP and UHP rocks. Gondwana Research, 25(2): 464-493
[6] Cao YT, Liu L, Wang C, Chen DL and Zhang AD. 2009. P-T path of Early Paleozoic pelitic high-pressure granulite from Danshuiquan area in Altyn Tagh. Acta Petrologica Sinica, 25(9): 2260-2270 (in Chinese with English abstract)
[7] Cao YT, Liu L, Wang C, Yang WQ and Zhu XH. 2010. Geochemical, zircon U-Pb dating and Hf isotope compositions studies for Tatelekebulake granite in South Altyn Tagh. Acta Petrologica Sinica, 26(11): 3259-3271 (in Chinese with English abstract)
[8] Chappell BW. 1999. Aluminium saturation in I- and S-type granites and the characterization of fractionated haplogranites. Lithos, 46(3): 535-551
[9] Chappell BW and White AJR. 2001. Two contrasting granite types: 25 years later. Australian Journal of Earth Sciences, 48(4): 489-499
[10] Claesson S, Vetrin V, Bayanova T and Downes H. 2000. U-Pb zircon ages from a Devonian carbonatite dyke, Kola Peninsula, Russia: A record of geological evolution from the Archaean to the Palaeozoic. Lithos, 51(1-2): 95-108
[11] Clemens JD and Watkins JM. 2001. The fluid regime of high-temperature metamorphism during granitoid magma genesis. Contributions to Mineralogy and Petrology, 140(5): 600-606
[12] Davies JH and von Blanckenburg F. 1995. Slab breakoff: A model of lithosphere detachment and its test in the magmatism and deformation of collisional orogens. Earth and Planetary Science Letters, 129(1-4): 85-102
[13] Deng JF, Luo ZH, Su SG, Mo XX, Ding BS, Lai XY and Chen HW. 2004. Petrogenesis and Tectonic Setting and Mineralization. Beijing: Geological Publishing House, 242-245 (in Chinese)
[14] Duretz T, Schmalholz SM and Gerya TV. 2012. Dynamics of slab detachment. Geochemistry, Geophysics, Geosystems, 13(3): Q03020
[15] Gao S, Luo TC, Zhang BR, Zhang HF, Han YW, Zhao ZD and Hu YK. 1998. Chemical composition of the continental crust as revealed by studies in East China. Geochimica et Cosmochimica Acta, 62(11): 1959-1975
[16] Ge XY, Li XH, Chen ZG and Li WP. 2002. Geochemistry and petrogenesis of Jurassic high Sr/low Y granitoids in eastern China: Constrains on crustal thickness. Chinese Science Bulletin, 47: 474-480 (in Chinese)
[17] Ghani AA, Searle M, Robb L and Chung SL. 2013. Transitional I- and S-type characteristic in the Main Range Granite, Peninsular Malaysia. Journal of Asian Earth Sciences, 76: 225-240
[18] He YS, Li SG, Hoefs J, Huang F, Liu SA and Hou ZH. 2011. Post-collisional granitoids from the Dabie orogen: New evidence for partial melting of a thickened continental crust. Geochimica et Cosmochimica Acta, 75(13): 3815-3838
[19] Johannes W and Holtz F. 1996. Petrogenesis and Experimental Petrology of Granitic Rocks. Berlin Heidelberg: Springer-Verlag
[20] Jung S and Pfänder JA. 2007. Source composition and melting temperatures of orogenic granitoids: Constraints from CaO/Na2O, Al2O3/TiO2 and accessory mineral saturation thermometry. European Journal of Mineralogy, 19(6): 859-870
[21] Kang L, Liu L, Cao YT, Wang C, Yang WQ and Liang S. 2013. Geochemistry, zircon U-Pb age and its geological significance of the gneissic granite from the eastern segment of the Tatelekebulake composite granite in the south Altyn Tagh. Acta Petrologica Sinica, 29(9): 3039-3048 (in Chinese with English abstract)
[22] Kang L, Liu L, Wang C, Cao YT, Yang WQ, Wang YW and Liao XY. 2014. Geochemistry and zircon U-Pb dating of Changshagou adakite from the South Altyn UHPM terrane: Evidence of the partial melting of the lower crust. Acta Geologica Sinica, 88(5): 1454-1465
[23] Kang L, Xiao PX, Gao XF, Xi RG and Yang ZC. 2015. Age, petrogenesis and tectonic implications of Early Devonian bimodal volcanic rocks in the South Altyn, NW China. Journal of Asian Earth Sciences, 111: 733-750
[24] Li CD, Zhang Q, Miao LC and Meng XF. 2004. Mesozoic high-Sr, low-Y and low-Sr, low-Y types granitoids in the northern Hebei Province: Geochemistry and petrogenesis and its relation to mineralization of gold deposits. Acta Petrologica Sinica, 20(2): 269-284 (in Chinese with English abstract)
[25] Li SG, Sun WD, Zhang GW, Chen JY and Yang YC. 1996. Chronology and geochemistry of metavolcanic rocks from Heigouxia valley in the Mian-Lue tectonic zone, South Qinling: Evidence for a paleozoic oceanic basin and its close time. Science in China (Series D), 39(3): 300-310
[26] Li SG. 2004. Exhumation mechanism of the ultrahigh-pressure metamorphic rocks in the Dabie mountains and continental collision process between the North and South China blocks. Earth Science Frontiers, 11(3): 63-70 (in Chinese with English abstract)
[27] Li SG, Li QL, Hou ZH, Yang W and Wang Y. 2005. Cooling history and exhumation mechanism of the ultrahigh-pressure metamorphic rocks in the Dabie Mountains, central China. Acta Petrologica Sinica, 21(4): 1117-1124 (in Chinese with English abstract)
[28] Li SG, He YS and Wang SJ. 2013. Process and mechanism of mountain-root removal of the Dabie Orogen: Constraints from geochronology and geochemistry of post-collisional igneous rocks. Chinese Science Bulletin, 58(35): 4411-4417
[29] Li ZH, Xu ZQ and Gerya TV. 2011. Flat versus steep subduction: Contrasting modes for the formation and exhumation of high- to ultrahigh-pressure rocks in continental collision zones. Earth and Planetary Science Letters, 301, 65-77
[30] Li ZH, Xu ZQ, Gerya T and Burg JP. 2013. Collision of continental corner from 3-D numerical modeling. Earth and Planetary Science Letters, 380: 98-111
[31] Li ZH. 2014. A review on the numerical geodynamic modeling of continental subduction, collision and exhumation. Science China (Earth Sciences), 57: 47-69
[32] Liu L, Che ZC, Luo JH, Wang Y and Gao ZJ. 1997. Recognition and implication of eclogite in the western Altun Mountains, Xinjiang. Chinese Science Bulletin, 42(11): 931-934
[33] Liu L, Che ZC, Wang Y, Luo JH and Chen DL. 1999. The petrological characters and geotectonic setting of high-pressure metamorphic rock belts in Altun Mountains. Acta Petrologica Sinica, 15(1): 57-64 (in Chinese with English abstract)
[34] Liu L, Sun Y, Xiao PX, Che ZC, Luo JH, Chen DL, Wang Y, Zhang AD, Chen L and Wang YH. 2002. Discovery of ultrahighpressure magnesite-bearing garnet lherzolite (>3.8GPa) in the Altyn Tagh, Northwest China. Chinese Science Bulletin, 47(11): 881-886
[35] Liu L, Sun Y, Luo JH, Wang Y, Chen DL and Zhang AD. 2004. Ultra-high pressure metamorphism of granitic gneiss in the Yinggelisayi area, Altun Mountains, NW China. Science in China (Series D), 47(4): 338-346
[36] Liu L, Chen DL, Zhang AD, Sun Y, Wang Y, Yang JX and Luo JH. 2005. Ultrahigh pressure (>7GPa) gneissic K-feldspar (-bearing) garnet clinopyroxenite in the Altyn Tagh, NW China: Evidence from clinopyroxene exsolution in garnet. Science in China (Series D), 48(7): 1000-1010
[37] Liu L, Zhang JF, Green II HW, Jin ZM and Bozhilov KN. 2007. Evidence of former stishovite in metamorphosed sediments, implying subduction to >350km. Earth and Planetary Science Letter, 263(3-4): 180-191
[38] Liu L, Zhang AD, Chen DL, Yang JX, Luo JH and Wang C. 2007. Implications based on LA-ICP-MS zircon U-Pb ages of eclogite and its country rock from Jianggalesayi area, Altyn Tagh. Earth Science Frontiers, 14(1): 98-107 (in Chinese with English abstract)
[39] Liu L, Wang C, Chen DL, Zhang AD and Liou JG. 2009. Petrology and geochronology of HP-UHP rocks from the South Altyn Tagh, northwestern China. Journal of Asian Earth Sciences, 35(3-4): 232-244
[40] Liu L, Wang C, Cao YT, Chen DL, Kang L, Yang WQ and Zhu XH. 2012. Geochronology of multi-stage metamorphic events: Constraints on episodic zircon growth from the UHP eclogite in the South Altyn, NW China. Lithos, 136-139: 10-26
[41] Liu L, Cao YT, Chen DL, Zhang CL, Yang WQ, Kang L and Liao XY. 2013. New progresses on the HP-UHP metamorphism in the South Altyn Tagh and the North Qinling. Chinese Science Bulletin, 58: 2113-2123 (in Chinese)
[42] Ludwig KR. 2003. Isoplot 3.0: A geochronological Toolkit for Microsoft Excel. Berkeley: Berkeley Geochronology Center, Special Publication, 4: 1-70
[43] Ma ZP, Li XM, Sun JM, Xu XY, Lei YX, Wang LS and Duan XX. 2009. Discovery of layered mafic-ultramafic intrusion in Changshagou, Altyn Tagh, and its geological implication: A pilot study on its petrological and geochemical characteristics. Acta Petrologica Sinica, 25(4): 793-804 (in Chinese with English abstract)
[44] Ma ZP, Li XM, Xu XY, Sun JM, Tang Z and Du T. 2011. Zircon LA-ICP-MS U-Pb isotopic dating for Qingshuiquan layered mafic-ultramafic intrusion southern Altun orogen, in northwestern China and its implication. Geology in China, 38(4): 1071-1078 (in Chinese with English abstract)
[45] Middlemost EAK. 1985. Magmas and Magmatic Rocks. London: Longman, 1-266
[46] Miller CF, Schuster R, Klötzli U, Frank W and Purtscheller. 1999. Post-collisional potassic and ultrapotassic magmatism in SW Tibet: Geochemical and Sr-Nd-Pb-O isotopic constraints for mantle source characteristics and petrogenesis. Journal of Petrology, 40(9): 1399-1424
[47] Miller CF, McDowell SM and Mapes RW. 2003. Hot and cold granites? Implications of zircon saturation temperatures and preservation of inheritance. Geology, 31(6): 529-532
[48] Patiño Douce AE. 2005. Vapor-absent melting of tonalite at 15-32kbar. Journal of Petrology, 46(2): 275-290
[49] Peccerillo A and Taylor SR. 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contributions to Mineralogy and Petrology, 58(1): 63-81
[50] Pitcher WS. 1983. Granite type and tectonic environment. In: Hsu KJ (ed.). Mountain Building Processes. London: Academic Press, 19-40
[51] Richards JP, Boyce AJ and Pringle MS. 2001. Geologic evolution of the Escondida Area, Northern Chile: A model for spatial and temporal localization of porphyry Cu mineralization. Economic Geology, 96(2): 271-305
[52] Rudnick RL and Gao S. 2003. Composition of the continental crust. In: Rudnick RL (ed.). Treatise on Geochemistry. Amsterdam: Elsevier, 3: 1-64
[53] Royden RH, Burchfiel BC and van der Hilst RD. 2008. The geological evolution of the Tibetan Plateau. Science, 321: 1054-1058
[54] Sun JM, Ma ZP, Tang Z and Li XM. 2012. LA-ICP-MS zircon dating of the Yumuquan magma mixing granite in the southern Altyn Tagh and its tectonic significance. Acta Geologica Sinica, 86(2): 247-257 (in Chinese with English abstract)
[55] Sun SS and McDonough WF. 1989. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. In: Saunders AD and Norry MJ (eds.). Magmatism in the Ocean Basins. Geological Society, London, Special Publication, 42(1): 313-345
[56] Sun WD, Li SG, Chen YD and Li YJ. 2002. Timing of synorogenic granitoids in the South Qinling, central China: Constraints on the evolution of the Qinling-Dabie orogenic belt. The Journal of Geology, 110(4): 457-468
[57] Sylvester PJ. 1998. Post-collisional strongly peraluminous granites. Lithos, 45(1-4): 29-44
[58] Taylor SR and McLennan SM. 1985. The Continental Crust: Its Composition and Evolution. Oxford: Blackwell Scientific Publications, 1-312
[59] Toussaint G, Burov E and Jolivet L. 2004. Continental plate collision: Unstable vs. stable slab dynamics. Geology, 32(1): 33-36
[60] Vielzeuf D and Montel JM. 1994. Partial melting of metagreywackes. Part I: Fluid-absent experiments and phase relationships. Contributions to Mineralogy and Petrology, 117(4): 375-393
[61] Wang C, Liu L, Zhang AD, Yang WQ and Cao YT. 2008. Geochemistry and petrography of Early Paleozoic Yusupuleke Tagh rapakivi-textured granite complex, South Altyn: An example for magma mixing. Acta Petrologica Sinica, 24(12): 2809-2819 (in Chinese with English abstract)
[62] Wang C, Liu L, Chen DL and Cao YT. 2011. Petrology, geochemistry, geochronology, and metamorphic evolution of garnet peridotites from South Altyn Tagh UHP terrane, northwestern China: Records related to crustal slab subduction and exhumation history. In: Dobrzhinetskaya LF, Faryad SW, Wallis S and Cuthbert S (eds.). Ultrahigh-Pressure Metamorphism: 25 Years after the Discovery of Coesite and Diamond. New York: Elsevier, 541-577
[63] Wang C, Liu L, Yang WQ, Zhu XH, Cao YT, Kang L, Chen SF, Li RS and He SP. 2013. Provenance and ages of the Altyn complex in Altyn Tagh: Implications for the Early Neoproterozoic evolution of northwestern China. Precambrian Research, 230: 193-208
[64] Watson EB and Harrison TM. 1983. Zircon saturation revisited: Temperature and composition effects in a variety of crustal magma types. Earth and Planetary Science Letters, 64(2): 295-304
[65] Watson EB and Harrison TM. 2005. Zircon thermometer reveals minimum melting conditions on earliest earth. Science, 308(5723): 841-844
[66] Whalen JB, Currie KL and Chappell BW. 1987. A-type granites: Geochemical characteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology, 95(4): 407-419
[67] Winther KT. 1996. An experimentally based model for the origin of tonalitic and trondhjemitic melts. Chemical Geology, 127(1-3): 43-59
[68] Wolf MB and London D. 1994. Apatite dissolution into peraluminous haplogranitic melts: An experimental study of solubilities and mechanisms. Geochimica et Cosmochimica Acta, 58(19): 4127-4145
[69] Wu CL, Gao YH, Lei M, Qin HP, Liu CH, Li MZ, Frost BR and Wooden JL. 2014. Zircon SHRIMP U-Pb dating, Lu-Hf isotopic characteristics and petrogenesis of the Palaeozoic granites in Mangya area, southern Altun, NW China. Acta Petrologica Sinica, 30(8): 2297-2323 (in Chinese with English abstract)
[70] Wu FY, Ge WC and Sun DY. 2002. The definition, discrimination of adakites and their geological role. In: Xiao QH, Deng JF, Ma DQ et al. (eds.). The Ways of Investigation on Granitoids. Beijing: Geological Publishing House, 172-191 (in Chinese with English abstract)
[71] Wu FY, Li XH, Yang JH and Zheng YF. 2007. Discussions on the petrogenesis of granites. Acta Petrologica Sinica, 23(6): 1217-1238 (in Chinese with English abstract)
[72] Wu SP, Wu CL and Chen QL. 2007. Characteristics and tectonic setting of the Tula aluminous A-type granite at the south side of the Altyn Tagh fault, NW China. Geological Bulletin of China, 26(10): 1385-1392 (in Chinese with English abstract)
[73] Wu YB and Zheng YF. 2004. Genesis of zircon and its constraints on interpretation of U-Pb age. Chinese Science Bulletin, 49(15): 1554-1569
[74] Xiao PX, Wang YH, Zhang HW, Pan CL and Sun NJ. 2001. The discovery of magnesite-bearing garnet lherzolite of high-ultrahigh pressure belt and its geological significance in the middle section of Altgn Tagh. Northwestern Geology, 34(4): 67-74 (in Chinese with English abstract)
[75] Xiong XL. 2006. Trace element evidence for growth of early continental crust by melting of rutile-bearing hydrous eclogite. Geology, 34(11): 945-948
[76] Xiong XL, Liu XC, Zhu ZM, Li Y, Xiao WS, Song MS, Zhang S and Wu JH. 2011. Adakitic rocks and destruction of the North China Craton: Evidence from experimental petrology and geochemistry. Science China (Earth Science), 54: 858-870
[77] Xu ZQ, Yang JS, Zhang JX, Jiang M, Li HB and Cui JW. 1999. A comparison between the tectonic units on the two sides of the Altun sinistral strike-slip fault and the mechanism of lithospheric shearing. Acta Geologica Sinica, 73(3): 193-205 (in Chinese with English abstract)
[78] Yang WQ, Liu L, Ding HB, Xiao PX, Cao YT and Kang L. 2012. Geochemistry, geochronology and zircon Hf isotopes of the Dimunalike granite in South Altyn Tagn and its geological significance. Acta Petrologica Sinica, 28(12): 4139-4150 (in Chinese with English abstract)
[79] Yin A, Rumelhart PE, Butler R, Cowgill E, Harrison TM, Foster DA, Ingersoll RV, Zhan Q, Zhou XQ, Wang XF, Hanson A and Raza A. 2002. Tectonic history of the Altyn Tagh fault system in northern Tibet inferred from Cenozoic sedimentation. Geological Society of America Bulletin, 114(10): 1257-1295
[80] Yuan HL, Gao S, Dai MN, Zong CL, Günther D, Fontaine GH, Liu XM and Diwu CR. 2008. Simultaneous determinations of U-Pb age, Hf isotopes and trace element compositions of zircon by excimer laser-ablation quadrupole and multiple-collector ICP-MS. Chemical Geology, 247(1-2): 100-118
[81] Zhang AD, Liu L, Sun Y, Chen DL, Wang Y and Luo JH. 2004. SHRIMP U-Pb zircon ages for the UHP metamorphosed granitoid gneiss in Altyn Tagh and their geological significance. Chinese Science Bulletin, 49(23): 2527-2532
[82] Zhang HF, Gao S, Zhang BR, Zhong ZQ, Jia WL and Wang LS. 2001. Pb isotopic study on crustal structure of Dabie Mountains, central China. Geochimica, 30(4): 395-401 (in Chinese with English abstract)
[83] Zhang JX, Zhang ZM, Xu ZQ, Yang JS and Cui JW. 2001. Petrology and geochronology of eclogites from the western segment of the Altyn Tagh, northwestern China. Lithos, 56(2-3): 187-206
[84] Zhang JX, Xu ZQ, Yang JS, Zhang ZM and Cui JW. 2001. Petrology, geochemistry and geochronology of eclogites from the western segment of the Altun Tectonic Belt, northwestern China. Acta Gelogica Sinica, 75(2): 186-197 (in Chinese with English abstract)
[85] Zhang JX, Yang JS, Xu ZQ, Meng FC, Li HB and Shi RD. 2002. Evidence for UHP metamorphism of eclogites from the Altun Mountains. Chinese Science Bulletin, 47(9): 751-755
[86] Zhang JX and Meng FC. 2005. Sapphirine-bearing high pressure mafic granulite and its implications in the South Altyn Tagh. Chinese Science Bulletin, 50(3): 265-269
[87] Zhang Q, Wang Y, Li CD, Wang YL, Jin WJ and Jia XQ. 2006. Granite classification on the basis of Sr and Yb contents and its implications. Acta Petrologica Sinica, 22(9): 2249-2269 (in Chinese with English abstract)
[88] Zhao ZH. 2010. Trace element geochemistry of accessory minerals and its applications in petrogenesis and metallogenesis. Earth Science Frontiers, 17(1): 267-286 (in Chinese with English abstract)
[89] Zhou Y and Pan YS. 1999. The initial shear sense of the Altun fault and its timing. Geological Review, 45(1): 1-9 (in Chinese with English abstract)
[90] 曹玉亭, 刘良, 王超, 陈丹玲, 张安达. 2009. 阿尔金淡水泉早古生代泥质高压麻粒岩及其P-T演化轨迹. 岩石学报, 25(9): 2260-2270
[91] 曹玉亭, 刘良, 王超, 杨文强, 朱小辉. 2010. 阿尔金南缘塔特勒克布拉克花岗岩的地球化学特征、锆石U-Pb定年及Hf同位素组成. 岩石学报, 26(11): 3259-3271
[92] 邓晋福, 罗照华, 苏尚国, 莫宣学, 丁炳松, 赖兴运, 谌宏伟. 2004. 岩石成因、构造环境与成矿作用. 北京: 地质出版社, 242-245
[93] 葛小月,李献华,陈志刚,李伍平. 2002. 中国东部燕山期高Sr低Y型中酸性火成岩的地球化学特征及成因——对中国东部地壳厚度的制约. 科学通报, 47 (6): 474-480
[94] 康磊, 刘良, 曹玉亭, 王超, 杨文强, 梁莎. 2013. 阿尔金南缘塔特勒克布拉克复式花岗质岩体东段片麻状花岗岩的地球化学特征、锆石U-Pb定年及其地质意义. 岩石学报, 29(9): 3039-3048
[95] 李承东, 张旗, 苗来成, 孟宪锋. 2004. 冀北中生代高Sr低Y和低Sr低Y型花岗岩: 地球化学、成因及其与成矿作用的关系. 岩石学报, 20(2): 269-284
[96] 李曙光, 孙卫东, 张国伟, 陈家义, 杨永成. 1996. 南秦岭勉略构造带黑沟峡变质火山岩的年代学和地球化学——古生代洋盆及其闭合时代的证据. 中国科学(D辑), 26(3): 223-230
[97] 李曙光. 2004. 大别山超高压变质岩折返机制与华北-华南陆块碰撞过程. 地学前缘, 11(3): 63-70
[98] 李曙光, 李秋立, 侯振辉, 杨蔚, 王莹. 2005. 大别山超高压变质岩的冷却史及折返机制. 岩石学报, 21(4): 1117-1124
[99] 李曙光, 何永胜, 王水炯. 2013. 大别造山带的去山根过程与机制: 碰撞后岩浆岩的年代学和地球化学制约. 科学通报, 58(23): 2316-2322
[100] 刘良, 车自成, 王焰, 罗金海, 陈丹玲. 1999. 阿尔金高压变质岩带的特征及其构造意义. 岩石学报, 15(1): 57-64
[101] 刘良, 张安达, 陈丹玲, 杨家喜, 罗金海, 王超. 2007. 阿尔金江尕勒萨依榴辉岩和围岩锆石LA-ICP-MS微区原位定年及其地质意义. 地学前缘, 14(1): 98-107
[102] 刘良, 曹玉亭, 陈丹玲, 张成立,杨文强,康磊,廖小英. 2013. 南阿尔金与北秦岭高压-超高压变质作用研究新进展. 科学通报, 58: 2113-2123
[103] 马中平, 李向民, 孙吉明, 徐学义, 雷永孝, 王立社, 段星星. 2009. 阿尔金山南缘长沙沟镁铁-超镁铁质层状杂岩体的发现与地质意义——岩石学和地球化学初步研究. 岩石学报, 25(4): 793-804
[104] 马中平, 李向民, 徐学义, 孙吉明, 唐卓, 杜涛. 2011. 南阿尔金山清水泉镁铁-超镁铁质侵入体LA-ICP-MS锆石U-Pb同位素定年及其意义. 中国地质, 38(4): 1071-1078
[105] 桑隆康, 马昌前. 2012. 岩浆起源和演变. 见: 桑隆康, 马昌前著. 岩石学.第二版. 北京: 地质出版社, 235-238
[106] 孙吉明, 马中平, 唐卓, 李向民. 2012. 阿尔金南缘鱼目泉岩浆混合花岗岩LA-ICP-MS测年与构造意义. 地质学报, 86(2): 247-257
[107] 王超, 刘良, 张安达, 杨文强, 曹玉亭. 2008. 阿尔金造山带南缘岩浆混合作用: 玉苏普阿勒克塔格岩体岩石学和地球化学证据. 岩石学报, 24(12): 2809-2819
[108] 吴才来, 郜源红, 雷敏, 秦海鹏, 刘春花, 李名则, Frost BR, Wooden JL. 2014. 南阿尔金茫崖地区花岗岩类锆石SHRIMP U-Pb定年、Lu-Hf同位素特征及岩石成因. 岩石学报, 30(8): 2297-2323
[109] 吴福元, 葛文春, 孙德有. 2002. 埃达克岩的概念、识别标志及其地质意义. 见: 肖庆辉, 邓晋福, 马大铨等著. 花岗岩研究思维与方法. 北京: 地质出版社, 172-191
[110] 吴福元, 李献华, 杨进辉, 郑永飞. 2007. 花岗岩成因研究的若干问题. 岩石学报, 23(6): 1217-1238
[111] 吴锁平, 吴才来, 陈其龙. 2007. 阿尔金断裂南侧吐拉铝质A型花岗岩的特征及构造环境. 地质通报, 26(10): 1385-1392
[112] 吴元保, 郑永飞. 2004. 锆石成因矿物学研究及其对U-Pb年龄解释的制约. 科学通报, 49(16): 1589-1604
[113] 校培喜, 王永和, 张汉文, 潘长利, 孙南一. 2001. 阿尔金山中段高压-超高压带(含菱镁矿)石榴子石二辉橄榄岩的发现及其地质意义. 西北地质, 34(4): 67-74
[114] 熊小林, 刘星成, 朱志敏, 李元, 肖万生, 宋茂双, 张生, 吴金花. 2011. 华北埃达克质岩与克拉通破坏: 实验岩石学和地球化学依据. 中国科学(地球科学), 41(5): 654-667
[115] 许志琴, 杨经绥, 张建新, 姜枚, 李海兵, 崔军文. 1999. 阿尔金断裂两侧构造单元的对比及岩石圈剪切机制. 地质学报, 73(3): 193-205
[116] 杨文强, 刘良, 丁海波, 校培喜, 曹玉亭, 康磊. 2012. 南阿尔金迪木那里克花岗岩地球化学、锆石U-Pb年代学与Hf同位素特征及其构造地质意义. 岩石学报, 28(12): 4139-4150
[117] 张宏飞, 高山, 张本仁, 钟增球, 贾望鲁, 王林森. 2001. 大别山地壳结构的Pb同位素地球化学示踪. 地球化学, 30(4): 395-401
[118] 张建新, 许志琴, 杨经绥, 张泽明, 崔军文. 2001. 阿尔金西段榴辉岩岩石学、地球化学和同位素年代学研究及其构造意义. 地质学报, 75(2): 186-197
[119] 张旗, 王焰, 李承东, 王元龙, 金惟俊, 贾秀勤. 2006. 花岗岩的Sr-Yb分类及其地质意义. 岩石学报, 22(9): 2249-2269
[120] 赵振华. 2010. 副矿物微量元素地球化学特征在成岩成矿作用研究中的应用. 地学前缘, 17(1): 267-286
[121] 周勇, 潘裕生. 1999. 阿尔金断裂早期走滑运动方向及其活动时间探讨. 地质论评, 45(1): 1-9