大別山千鵝沖鉬礦區(qū)花崗巖的SHRIMP鋯石U-Pb年齡、Hf同位素組成及微量元素特征**

高陽(yáng) 葉會(huì)壽 李永峰 羅正傳 李法嶺 熊必康 孟芳GAO Yang, YE HuiShou*, LI YongFeng, LUO ZhengZhuan, LI FaLing, XIONG BiKang and MENG Fang

1. 中國(guó)地質(zhì)科學(xué)院礦產(chǎn)資源研究所，國(guó)土資源部成礦作用與資源評(píng)價(jià)重點(diǎn)實(shí)驗(yàn)室，北京 1000372. 河南省有色金屬地質(zhì)礦產(chǎn)局，鄭州 4500163. 河南省地礦局第三地質(zhì)調(diào)查隊(duì)，信陽(yáng) 4640004. 中國(guó)地質(zhì)大學(xué)，北京 1000831. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China2. Henan Provincial Non-ferrous Metals Geological and Mineral Resources Bureau, Zhengzhou 450016, China3. No. 3 Geological Survey, Henan Bureau of Geology and Mineral Resources, Xinyang 464000, China4. China University of Geosciences, Beijing 100083, China2013-09-02 收稿, 2013-12-07 改回.

1 引言

千鵝沖鉬礦床位于秦嶺-大別造山帶東部的大別山地區(qū)，是東秦嶺-大別鉬礦帶近年來(lái)發(fā)現(xiàn)的一處超大型鉬礦床，已探明鉬資源量60萬(wàn)噸，平均品位0.08%(李法嶺，2011；Maoetal., 2011a)。2006年開(kāi)始，河南省第三地質(zhì)調(diào)查隊(duì)在千鵝沖地區(qū)實(shí)現(xiàn)了找礦突破，發(fā)現(xiàn)了礦區(qū)南部南灣組片巖中的千鵝沖隱伏巖體及其上部的隱伏礦體，最終確定其為超大型規(guī)模，并且是大別山地區(qū)發(fā)現(xiàn)的第一個(gè)超大型鉬礦床。千鵝沖鉬礦床的發(fā)現(xiàn)不僅結(jié)束了大別山地區(qū)無(wú)超大型礦床的歷史，同時(shí)對(duì)區(qū)域上找礦勘探也具有十分重要的指導(dǎo)意義。

自千鵝沖鉬礦發(fā)現(xiàn)以后，多位學(xué)者就其成礦成巖時(shí)代、成礦流體特征等進(jìn)行了研究。研究結(jié)果表明，千鵝沖鉬礦輝鉬礦Re-Os同位素年齡為128±8Ma(李法嶺，2011；楊梅珍等，2010)，成礦作用發(fā)生在早白堊世；成礦流體為高溫、高鹽度、貧子晶、富CO2的流體系統(tǒng)(Yangetal., 2013)。鉆探工程揭露礦體下部存在隱伏巖體，并且與礦體具有緊密的空間關(guān)系，所以對(duì)千鵝沖隱伏巖體進(jìn)行年代學(xué)研究對(duì)于揭示成巖成礦關(guān)系及成礦機(jī)制都具有重要意義。本次研究對(duì)礦體下部隱伏的二長(zhǎng)花崗巖和花崗斑巖進(jìn)行了SHRIMP鋯石U-Pb同位素定年，從而精確厘定了千鵝沖隱伏巖體的形成時(shí)代，并通過(guò)鋯石原位Hf同位素及鋯石微量元素分析，淺析千鵝沖隱伏巖體的成因、構(gòu)造背景及與成礦的關(guān)系，同時(shí)為深入研究大別山地區(qū)白堊紀(jì)鉬成礦作用與區(qū)域大規(guī)?；◢徺|(zhì)巖漿作用的關(guān)系提供了重要依據(jù)。

2 區(qū)域地質(zhì)背景

大別造山帶是秦嶺-大別-蘇魯造山帶的組成部分，形成于三疊紀(jì)華北與華南兩板塊的碰撞拼合(圖1)(張國(guó)偉等，2001；Hackeretal., 1998；Lietal., 2001；Ratschbacheretal., 2003)。大別造山帶西起河南桐柏山，向西以南陽(yáng)盆地為界與秦嶺造山帶相望，東側(cè)為郯城-廬江斷裂，此斷裂使大別造山帶和蘇魯造山帶之間位移約500km。大別造山帶南北邊界分別為襄樊-廣濟(jì)斷裂和欒川-明港-固始斷裂。

大別造山帶以商城-麻城斷裂為界可分為東大別和西大別兩部分。東大別從北到南分別以曉天-磨子潭斷裂(XMF)、五河-水吼斷裂(WSF)和太湖-馬廟斷裂(TMF)為邊界可劃分出4個(gè)巖石-構(gòu)造單元(Lietal., 2001；向必偉，2009)：(1)北淮陽(yáng)構(gòu)造帶，主要包括一套在華南板塊向華北板塊俯沖時(shí)刮削下來(lái)所形成的低級(jí)變質(zhì)地體(Zhengetal., 2005)，變質(zhì)巖原巖具有700～800Ma的鋯石U-Pb年齡(Hackeretal., 2000；Chenetal., 2003)；(2)北大別雜巖帶，主要由大規(guī)模白堊紀(jì)花崗巖及少量鎂鐵-超鎂鐵質(zhì)侵入巖、新元古代TTG片麻巖和角閃巖、三疊紀(jì)榴輝巖、少量變質(zhì)沉積巖和麻粒巖以及少量橄欖巖組成(Hackeretal., 2000；Bryantetal., 2004；Liuetal., 2005；Xuetal., 2000；Zhengetal., 2003)；(3)南大別高壓-超高壓變質(zhì)帶，以產(chǎn)出含柯石英和金剛石榴輝巖為特征(Wangetal.,1989)，主要包括榴輝巖、含石榴石橄欖巖、硬玉石英巖、大理巖、石榴石-二云母片巖及片麻巖(Hackeretal., 1998, 2000；Xuetal., 2003)；(4)宿松雜巖帶，主要包含中-新元古代變質(zhì)沉積巖和變質(zhì)火山巖以及震旦紀(jì)大理巖(Youetal., 1996)。西大別具有與東大別相似的巖石-構(gòu)造單元組成，不同的是西大別缺少與“北大別雜巖帶”相對(duì)應(yīng)的構(gòu)造單元。

大別山地區(qū)發(fā)育大量中生代巖漿巖，其顯著特點(diǎn)是全部形成于早白堊世，主要包括大量中酸性侵入巖及少量鎂鐵-超鎂鐵質(zhì)巖和火山巖(Fanetal., 2004；Heetal., 2011, 2013；Huangetal., 2008；Wangetal., 2007；Zhaoetal., 2005)。早白堊世花崗巖類(lèi)侵位時(shí)間為117～143Ma(Heetal., 2011；Wangetal., 2007)，可分為兩期，早期巖體(130～143Ma)通常具有高的Sr/Y和La/Yb比值，而晚期巖體則通常不具備這一特征(Wangetal., 2007；Xuetal., 2007)?；鹕綆r主要分布在北淮陽(yáng)構(gòu)造帶內(nèi)，主要包括玄武質(zhì)粗安巖、粗安巖及粗面巖等(Fanetal., 2004)。鎂鐵-超鎂鐵質(zhì)侵入巖主要發(fā)育在北大別雜巖帶內(nèi)，時(shí)代為123～130Ma，主要包括輝石巖、角閃石巖、輝長(zhǎng)巖等(Daietal., 2011；Huangetal., 2007；Wangetal., 2005；Zhaoetal., 2005)。

目前在大別山地區(qū)發(fā)現(xiàn)的斑巖型鉬礦床主要分布在中西部的北淮陽(yáng)構(gòu)造帶及臨近地區(qū)(圖1)。斑巖鉬礦與早白堊世中酸性小斑巖體具有緊密的時(shí)空關(guān)系，其產(chǎn)出明顯受網(wǎng)格狀斷裂構(gòu)造的控制。

圖1 桐柏-大別山地區(qū)地質(zhì)圖(據(jù)Ratschbacher et al., 2003修改)白堊紀(jì)花崗巖及鎂鐵-超鎂鐵質(zhì)巖引自Ratschbacher et al., 2003；He et al., 2011；Zhao et al., 2005. ZXF, GMF, XMF, TSF, DSHF, SMF, WSF, TMF and TLF分別代表朱陽(yáng)關(guān)-夏館斷裂、龜山-梅山斷裂、曉天-磨子潭斷裂、桐柏-商城斷裂、陡山河斷裂、商城-麻城斷裂、五河-水吼斷裂、太湖-馬廟斷裂及郯城-廬江斷裂Fig.1 Generalized geological map of the Tongbai-Dabie area in East China (modified after Ratschbacher et al., 2003)Cretaceous granites and mafic-ultramafic intrusive rocks are from Ratschbacher et al., 2003; He et al., 2011; Zhao et al., 2005. ZXF, GMF, XMF, TSF, DSHF, SMF, WSF, TMF and TLF represent the Zhuyangguan-Xiaguan Fault, the Guishan-Meishan Fault, the Xiaotian-Mozitan Fault, the Tongbai-Shangcheng Fault, the Doushanhe Fault, the Shangcheng-Macheng Fault, the Wuhe-Shuihou Fault, the Taihu-Mamiao Fault and Tancheng-Lujiang Fault, respectively

3 礦床地質(zhì)特征

千鵝沖鉬礦床位于西大別北淮陽(yáng)構(gòu)造帶內(nèi)，區(qū)域性桐柏-商城斷裂帶北側(cè)(圖1)。礦區(qū)出露地層比較簡(jiǎn)單，絕大部分為泥盆系南灣組(Dn)淺變質(zhì)云母石英片巖系，另外在礦區(qū)西南部邊界分布少量震旦系-下奧陶統(tǒng)肖家廟巖組(Z-O1x3)地層以及溝谷中出露的第四系(圖2)。區(qū)內(nèi)地層走向北西西，與區(qū)域構(gòu)造線(xiàn)一致。肖家廟巖組與南灣組以桐-商韌性剪切帶為界，呈構(gòu)造接觸，構(gòu)造帶以南為肖家廟巖組地層，以北為南灣組地層。

礦區(qū)內(nèi)無(wú)大的褶皺構(gòu)造，構(gòu)造主要為斷裂構(gòu)造。斷裂構(gòu)造分為韌性斷裂和脆性斷裂。韌性斷裂為區(qū)域性桐(柏)-商(城)韌性剪切帶的一部分，出露于礦區(qū)南部，為肖家廟巖組與南灣組地層的分界(圖2)，韌性剪切帶內(nèi)的構(gòu)造巖以云英質(zhì)構(gòu)造片巖為主，次為長(zhǎng)英質(zhì)變晶糜棱巖。脆性斷裂是礦區(qū)內(nèi)的主要構(gòu)造形態(tài)，主要發(fā)育在礦區(qū)中部南灣組地層中，主要為北西西向和近南北向兩組。地表沿?cái)嗔逊植家幌盗袠?gòu)造蝕變巖帶，帶內(nèi)巖石發(fā)生較強(qiáng)硅化、鉀長(zhǎng)石化、碳酸鹽化及褐鐵礦化，部分地段發(fā)現(xiàn)鉬、銅、鉛鋅、銀礦化。

千鵝沖礦區(qū)地表無(wú)大巖體出露，經(jīng)鉆探驗(yàn)證，在礦區(qū)中南部存在隱伏巖體(圖2b)，鉆孔揭露其頂部標(biāo)高為-512.71～-751.29m，巖體呈起伏狀與圍巖侵入接觸，局部有震碎現(xiàn)象。鉆孔控制隱伏巖體平面投影面積約0.262km2。該巖體為礦區(qū)鉬礦的成礦母巖，其與圍巖接觸帶可見(jiàn)強(qiáng)弱不等的蝕變，類(lèi)型主要有硅化、鉀長(zhǎng)石化、絹云母化和黃鐵礦化，并伴生鉬礦化，但礦化強(qiáng)度弱于上部圍巖。巖體主要由花崗斑巖和二長(zhǎng)花崗巖組成，鉆孔中揭露的花崗斑巖含量遠(yuǎn)多于二長(zhǎng)花崗巖，二長(zhǎng)花崗巖只在局部可見(jiàn)。除此之外，區(qū)內(nèi)燕山晚期中酸性小型脈巖較發(fā)育，按巖石類(lèi)型可分為閃長(zhǎng)玢巖脈、煌斑巖脈、石英斑巖脈和花崗斑巖脈。

除少量礦體產(chǎn)于隱伏巖體內(nèi)接觸帶，絕大部分礦體產(chǎn)于南灣組片巖中。賦礦巖石主要為綠簾黑云石英片巖、綠簾黑云片巖、含綠簾二云石英片巖、黑云斜長(zhǎng)石英片巖、黑云石英片巖等，礦體與圍巖均呈漸變過(guò)渡關(guān)系，無(wú)明顯界限。金屬礦物主要為輝鉬礦、黃鐵礦、黃銅礦、方鉛礦、閃鋅礦、磁鐵礦、赤鐵礦等；脈石礦物主要為石英、鉀長(zhǎng)石、綠簾石、方解石、黑云母、絹云母、白云母、綠泥石、螢石。主要的礦石結(jié)構(gòu)包括自形-半自形-他形結(jié)晶結(jié)構(gòu)、交代結(jié)構(gòu)、壓碎結(jié)構(gòu)、固溶體出溶結(jié)構(gòu)等。礦石構(gòu)造類(lèi)型主要有脈狀構(gòu)造、浸染狀構(gòu)造、角礫狀構(gòu)造等。礦區(qū)內(nèi)常見(jiàn)的圍巖蝕變有硅化、鉀長(zhǎng)石化、黃鐵礦化、絹云母化、綠簾石化、綠泥石化、碳酸鹽化等，多疊加出現(xiàn)，強(qiáng)弱不等。以硅化、鉀長(zhǎng)石化、黃鐵礦化、絹云母化發(fā)育較強(qiáng)。

圖2 千鵝沖鉬礦地質(zhì)簡(jiǎn)圖及勘探線(xiàn)剖面圖(據(jù)河南省地礦局第三地質(zhì)調(diào)查隊(duì)，2011*河南省地礦局第三地質(zhì)調(diào)查隊(duì). 2011. 河南省光山縣千鵝沖鉬礦勘探報(bào)告)

Fig.2 Simplified geological map and cross-section of the Qian’echong Mo deposit

圖3 千鵝沖巖體手標(biāo)本及顯微照片(a)-二長(zhǎng)花崗巖與花崗斑巖的侵入接觸關(guān)系；(b)-二長(zhǎng)花崗巖；(c)-花崗斑巖. Q-石英；Kf-鉀長(zhǎng)石；Pl-斜長(zhǎng)石；Bi-黑云母；Chl-綠泥石Fig.3 Hand specimens and photomicrographs showing petrology of Qian’echong stock(a)-intrusive contact relationship of monzogranite and granite porphyry; (b)-monzogranite; (c)-granite porphyry. Q-quartz; Kf-K-feldspar; Pl-plagioclase; Bi-biotite; Chl-chloritic

4 樣品描述及分析方法

本次研究所采集的二長(zhǎng)花崗巖(QEC-7)和花崗斑巖(QEC-8)來(lái)自ZK005鉆孔985m處，可見(jiàn)花崗斑巖在與二長(zhǎng)花崗巖的接觸部位有冷凝邊(圖3a)，其形成晚于二長(zhǎng)花崗巖。其中，二長(zhǎng)花崗巖為灰白色，細(xì)粒結(jié)構(gòu)，塊狀構(gòu)造(圖3b)。主要礦物為石英(20%～25%)、正長(zhǎng)石(35%～40%)、斜長(zhǎng)石(30%～35%)；次要礦物為黑云母，含量2%～4%；副礦物主要有鋯石、磷灰石、榍石、磁鐵礦、鈦鐵礦等，含量1%～3%。大部分巖石發(fā)生較強(qiáng)的硅化?；◢彴邘r，肉紅色-暗紅色，斑狀結(jié)構(gòu)，塊狀構(gòu)造(圖3c)。斑晶含量15%～20%，主要為正長(zhǎng)石(40%～50%)、石英(35%～40%)、斜長(zhǎng)石(15%～20%)及少量黑云母；基質(zhì)含量約為80%，礦物組成同斑晶，粒度0.1～0.4mm；副礦物主要有磁鐵礦、鈦鐵礦、鋯石、磷灰石等，含量為1%～5%。巖石普遍發(fā)生較強(qiáng)烈的鉀硅酸鹽化及硅化蝕變。

圖4 千鵝沖鉬礦二長(zhǎng)花崗巖和花崗斑巖代表性鋯石陰極發(fā)光圖像及測(cè)點(diǎn)位置、U-Pb年齡和εHf(t)值Fig.4 Cathodoluminescence (CL) images of representative zircon of monzogranite and granite porphyry from the Qian’echong Mo deposit with analytical numbers, U-Pb ages and εHf(t)

將巖石樣品破碎，經(jīng)重力和磁選后在雙目鏡下挑選出鋯石顆粒，并與標(biāo)準(zhǔn)鋯石一起置于環(huán)氧樹(shù)脂做成樣品靶，進(jìn)行鋯石透、反射光、陰極發(fā)光照相，以及SHRIMP定年、Lu-Hf同位素分析和鋯石微量元素測(cè)試。

鋯石分選工作在廊坊市地源礦物測(cè)試分選技術(shù)服務(wù)有限公司完成。鋯石陰極發(fā)光(CL)照相在中國(guó)地質(zhì)科學(xué)院地質(zhì)研究所北京離子探針中心完成。鋯石U-Pb年齡數(shù)據(jù)是在中國(guó)地質(zhì)科學(xué)院地質(zhì)研究所北京離子探針中心的網(wǎng)絡(luò)虛擬實(shí)驗(yàn)室，通過(guò)SHRIMP遠(yuǎn)程共享控制系統(tǒng)(SHRIMP Remote Operation System, SROS)遠(yuǎn)程控制位于澳大利亞Curtin理工大學(xué)(Curtin University of Technology)的SHRIMP II儀器獲得的，詳細(xì)測(cè)試方法見(jiàn)Williams(1998)。SHRIMP遠(yuǎn)程共享控制系統(tǒng)(SROS)由北京離子探針中心、中國(guó)計(jì)量科學(xué)研究院和吉林大學(xué)共同研發(fā)，可以實(shí)現(xiàn)通過(guò)Internet公共網(wǎng)絡(luò)，遠(yuǎn)程控制SHRIMP II儀器、遠(yuǎn)程選取樣品待測(cè)點(diǎn)和實(shí)時(shí)遠(yuǎn)程實(shí)驗(yàn)數(shù)據(jù)輸出打印等功能。數(shù)據(jù)處理采用SQUID和ISOPLOT程序(Ludwig, 2003)。

鋯石Lu-Hf同位素測(cè)試是在中國(guó)地質(zhì)科學(xué)院礦產(chǎn)資源研究所國(guó)土資源部成礦作用與資源評(píng)價(jià)重點(diǎn)實(shí)驗(yàn)室Neptune多接收等離子質(zhì)譜和Newwave UP213紫外激光剝蝕系統(tǒng)(LA-MC-ICP-MS)上進(jìn)行的，實(shí)驗(yàn)過(guò)程中采用He作為剝蝕物質(zhì)載氣，剝蝕直徑為55μm，測(cè)試時(shí)采用鋯石國(guó)際標(biāo)樣GJ1作為參考物質(zhì)，分析點(diǎn)與U-Pb定年分析點(diǎn)為同一位置。相關(guān)儀器運(yùn)行條件及詳細(xì)分析流程見(jiàn)侯可軍等(2007)。分析過(guò)程中鋯石標(biāo)準(zhǔn)GJ1的176Hf/177Hf測(cè)試加權(quán)平均值為0.282015±28(2σ,n=10)，與文獻(xiàn)報(bào)道值(侯可軍等，2007；Elhlouetal., 2006)在誤差范圍內(nèi)完全一致。

鋯石原位微量元素測(cè)試在國(guó)家地質(zhì)實(shí)驗(yàn)測(cè)試中心(NRCGA)完成，采用激光剝蝕等離子質(zhì)譜(LA-ICP-MS)方法。使用儀器為T(mén)hermo Element II 等離子質(zhì)譜儀，激光剝蝕系統(tǒng)為New Wave UP-213。實(shí)驗(yàn)中采用He 作為剝蝕物質(zhì)的載氣，激光波長(zhǎng)213nm、束斑40μm、脈沖頻率10Hz、能量0.176mJ、密度23～25J/cm2，測(cè)試過(guò)程中首先遮擋激光束進(jìn)行空白背景采集15s，然后進(jìn)行樣品連續(xù)剝蝕采集45s，停止剝蝕后繼續(xù)吹掃15s 清洗進(jìn)樣系統(tǒng)，單點(diǎn)測(cè)試分析時(shí)間75s。等離子質(zhì)譜測(cè)試參數(shù)為冷卻氣流速(Ar)15.55L/min；輔助氣流速(Ar)0.67L/min；載氣流速(He)0.58L/min；樣品氣流速0.819L/min，射頻發(fā)生器功率1205W。數(shù)據(jù)測(cè)試標(biāo)樣使用NIST-610。用于計(jì)算Ce4+和Ce3+在鋯石-熔體中的分配系數(shù)所用到的全巖微量元素含量測(cè)試在國(guó)家地質(zhì)實(shí)驗(yàn)測(cè)試中心完成，檢測(cè)儀器為等離子體質(zhì)譜儀ICP-MS(X-series)，測(cè)試精度優(yōu)于5%。

5 分析結(jié)果

5.1 SHRIMP鋯石U-Pb年齡

二長(zhǎng)花崗巖(QEC-7)和花崗斑巖(QEC-8)中的鋯石多呈柱狀，長(zhǎng)度一般為100～200μm，長(zhǎng)寬比大多為2:1～3:1，無(wú)色透明，具清晰震蕩環(huán)帶，裂紋不發(fā)育，顯示巖漿成因特征(Rubatto and Gebauer, 2000)(圖4)。本次研究中，對(duì)樣品Q(chēng)EC-7和QEC-8分別選擇了14個(gè)和16個(gè)點(diǎn)進(jìn)行測(cè)試，鋯石U-Pb定年結(jié)果列于表1。兩件樣品中絕大部分鋯石Th/U比值變化在0.56～1.99之間，屬典型巖漿鋯石特征(Belousovaeta., 2002)。QEC-7的14個(gè)測(cè)試點(diǎn)和QEC-8的15個(gè)測(cè)試點(diǎn)分別得到206Pb/238U年齡為130±2Ma(MSWD=1.4)和129±2Ma(MSWD=1.9)(圖5)，分別代表二長(zhǎng)花崗巖和花崗斑巖的結(jié)晶年齡。另外，樣品Q(chēng)EC-8中的一個(gè)測(cè)點(diǎn)3.1得到了1943±37Ma的年齡，沒(méi)有參與加權(quán)平均年齡的計(jì)算。以上測(cè)年結(jié)果顯示千鵝沖隱伏巖體中的二長(zhǎng)花崗巖和花崗斑巖形成于同一巖漿事件。

表1千鵝沖鉬礦床二長(zhǎng)花崗巖(QEC-7)和花崗斑巖(QEC-8)的SHRIMP鋯石U-Pb同位素定年結(jié)果

Table 1 Results of SHRIMP zircon U-Pb dating of monzogranite (QEC-7) and granite porphyry (QEC-8) from the Qian’echong Mo deposit

SpotNo.U(×10-6)Th(×10-6)Th/U206Pb*(×10-6)206Pbc(%)207Pb*235U±%(1σ)207Pb*206Pb*±%(1σ)206Pb*238U±%(1σ)206Pb238UAge(Ma)±Ma(1σ)QEC-7-1.116829440.5829.50.150.13522.90.04812.20.02041.9130.22.4QEC-7-2.1124816461.3622.71.130.14207.60.04917.30.02101.9133.62.5QEC-7-3.1127510780.8723.0—0.14672.40.05061.50.02101.9134.12.5QEC-7-4.12423471.484.21.720.11028.80.04068.50.01972.1125.82.6QEC-7-5.13654941.406.11.230.1150170.0431170.01932.2123.12.7QEC-7-6.12421730.744.2—0.16374.30.05873.80.02022.1129.12.7QEC-7-7.1150120471.4126.80.260.14153.30.04962.70.02071.9132.02.5QEC-7-8.184914101.7215.30.360.13314.30.04623.90.02091.9133.32.5QEC-7-9.1154816051.0727.30.310.14383.00.05092.30.02051.9130.72.4QEC-7-10.1101518511.8917.7—0.15704.30.05563.90.02051.9130.62.5QEC-7-11.11763391.993.11.720.1100190.0391190.02042.3130.13.0QEC-7-12.15004010.838.60.500.12777.40.04647.10.02002.0127.42.5QEC-7-13.11772451.433.10.990.1210150.0438150.02002.3127.82.9QEC-7-14.1151011180.7726.70.380.13563.90.04793.50.02051.9131.02.4QEC-8-1.174841.161.38.04————0.01934.0123.24.9QEC-8-2.14083320.847.1—0.172100.06149.80.02042.1130.02.7QEC-8-3.158330.5817.4—6.47007.70.13347.40.35172.2194337QEC-8-4.146700.008.50.820.14256.90.04906.60.02112.0134.52.6QEC-8-5.127800.005.01.350.1110130.0388120.02072.1132.12.7QEC-8-6.179800.0013.2—0.13443.30.05042.50.01932.2123.42.7QEC-8-7.146500.007.80.400.17293.30.06482.70.01942.0123.52.4QEC-8-8.16437491.2011.10.480.12813.80.04673.30.01991.9127.12.4QEC-8-9.19188901.0016.00.310.13495.60.04845.30.02021.9129.02.4QEC-8-10.1118415411.3420.7—0.13893.00.04942.40.02041.9130.12.4QEC-8-11.14512460.567.60.900.1240110.0461100.01952.0124.72.5QEC-8-12.1126510850.8921.90.260.13372.80.04822.10.02011.9128.52.4QEC-8-13.1166815390.9529.50.470.12794.30.04543.90.02051.9130.52.4QEC-8-14.14502930.677.8—0.15113.70.05453.10.02012.0128.32.5QEC-8-15.19399551.0516.9—0.14152.60.04901.80.02091.9133.62.5QEC-8-16.1219015140.7140.73.450.13317.20.04636.90.02091.9133.12.5

注：Pb*和Pbc分別代表放射鉛和普通鉛，鋯石中的普通鉛用實(shí)測(cè)204Pb校正; —表示未檢出

圖5 SHRIMP鋯石U-Pb年齡諧和圖及加權(quán)平均年齡Fig.5 Zircon U-Pb isotope concordian diagrams and weighted average ages

表2千鵝沖鉬礦床二長(zhǎng)花崗巖(QEC-7)和花崗斑巖(QEC-8)鋯石Hf同位素分析結(jié)果

Table 2 Zircon Hf isotopic composition of monzogranite (QEC-7) and granite porphyry (QEC-8) from the Qian’echong Mo deposit

SpotNo.176Yb/177Hf176Lu/177Hf176Hf/177Hf±2σ(176Hf/177Hf)iAge(Ma)εHf(t)tDM1(Ma)tDM2(Ma)QEC-7-1.10.0811110.0013290.2821490.0000200.282146130-19.315682408QEC-7-2.10.1339350.0024110.2822950.0000220.282289134-14.214032086QEC-7-3.10.1650890.0039830.2823200.0000230.282310134-13.414282037QEC-7-4.10.0844470.0017510.2822340.0000270.282229126-16.414652224QEC-7-5.10.1246460.0018570.2822780.0000210.282273123-14.914062127QEC-7-6.10.1003610.0019910.2822740.0000260.282270129-14.914172132QEC-7-7.10.1256450.0016860.2823460.0000300.282342132-12.313031969QEC-7-8.10.1561120.0020790.2826180.0000330.282612133-2.79251362QEC-7-9.10.0870800.0013110.2821590.0000280.282155131-18.915532385QEC-7-10.10.0745100.0012960.2820010.0000240.281997131-24.517742736QEC-7-11.10.0871600.0012340.2825000.0000280.282497130-6.910711624QEC-7-12.10.1355800.0031620.2821250.0000290.282118127-20.416832470QEC-7-13.10.0963390.0013780.2823760.0000310.282373128-11.312501902QEC-7-14.10.1195740.0029890.2822250.0000200.282218131-16.715282245QEC-8-1.10.1184460.0016410.2823300.0000250.282326123-13.113242010QEC-8-2.10.0818730.0012790.2821590.0000220.282156130-18.915512385QEC-8-3.10.0133800.0001960.2809940.0000190.2809871,943-19.830723787QEC-8-4.10.0663240.0011100.2822670.0000190.282264135-15.013942142QEC-8-5.10.0392970.0006000.2823350.0000250.282334132-12.612811988QEC-8-6.10.1079880.0021290.2823230.0000220.282318123-13.313512027QEC-8-7.10.0798330.0011540.2822810.0000210.282279124-14.713752116QEC-8-8.10.0699900.0010970.2823790.0000180.282376127-11.212361895QEC-8-9.10.0714910.0011840.2822350.0000210.282233129-16.214412215QEC-8-10.10.1084380.0019960.2823690.0000190.282364130-11.612811921QEC-8-11.10.1021630.0015780.2823730.0000240.282370125-11.512601912QEC-8-12.10.0750580.0013390.2823140.0000190.282311129-13.513362041QEC-8-13.10.0810800.0015310.2822200.0000180.282216131-16.814762250QEC-8-14.10.0844270.0012380.2823700.0000240.282367128-11.512531915QEC-8-15.10.1351150.0030770.2822740.0000250.282266134-14.914602136QEC-8-16.10.1051810.0017560.2822080.0000260.282204133-17.215022276

注：εHf(t)=10000×{[(176Hf/177Hf)S-(176Lu/177Hf)S×(eλt-1)]/[(176Hf/177Hf)CHUR,0-(176Lu/177Hf)CHUR×(eλt-1)]-1};tDM1=1/λ×ln{1+[(176Hf/177Hf)S-(176Hf/177Hf)DM]/[(176Lu/177Hf)S-(176Lu/177Hf)DM]};tDM2=1/λ×ln{1+[(176Hf/177Hf)S, t-(176Hf/177Hf)DM, t]/[(176Lu/177Hf)c-(176Lu/177Hf)DM]}+t; (176Lu/177Hf)S和(176Hf/177Hf)S為樣品測(cè)定值; (176Hf/177Hf)CHUR,0=0.282772, (176Lu/177Hf)CHUR=0.0332, (176Hf/177Hf)DM=0.28325, (176Lu/177Hf)DM=0.0384 (Blichert-Toft and Albarède, 1997; Griffinetal., 2000); λ=1.867×10-11/a (Soderlundetal., 2004); (176Lu/177Hf)c=0.015;t為鋯石結(jié)晶時(shí)間

5.2 鋯石Hf同位素

在SHRIMP鋯石U-Pb定年的基礎(chǔ)上，對(duì)樣品Q(chēng)EC-7和QEC-8進(jìn)行了鋯石微區(qū)Hf同位素測(cè)定，分析結(jié)果見(jiàn)表2和圖6。大部分鋯石的176Lu/177Hf比值小于0.002，說(shuō)明鋯石在形成后具有很少的放射成因Hf的積累，所測(cè)定的176Hf/177Hf比值基本代表了其形成時(shí)體系的Hf同位素組成。樣品Q(chēng)EC-7共分析14個(gè)點(diǎn)，176Hf/177Hf比值變化于0.282001～0.282618，εHf(t)值變化于-24.5～-2.7(絕大部分集中在-24.5～-11.3之間)，兩階段模式年齡(tDM2)變化于1362～2736Ma。樣品Q(chēng)EC-8共分析16個(gè)點(diǎn)，176Hf/177Hf比值變化于0.280994～0.282379，εHf(t)值較均一，變化于-19.8～-11.2，除一顆繼承鋯石的兩階段模式年齡(tDM2)為3787Ma外，其他變化于1895～2385Ma之間(圖6)。

表3千鵝沖鉬礦二長(zhǎng)花崗巖和花崗斑巖鋯石微量元素LA-ICP-MS測(cè)試結(jié)果(×10-6)

Table 3 Zircon trace element data of monzogranite and granite porphyry in the Qian’echong Mo deposit (×10-6)

測(cè)點(diǎn)號(hào)LaCePrNdSmEuGdTbDyHoErTmYbLuThUHfQEC-7(二長(zhǎng)花崗巖)10.0226.00.050.752.561.0910.83.4551.920.810620.228658.583.43421743120.411220.898.5112.84.4257.815.619496.144271.076016996118882168432.8382.31.709.3611.33.0340.813.018876.235862.571215167317381941640.2094.40.363.296.481.9434.810.314768.136367.7738168106616231924452.731333.6524.123.46.6774.921.724190.742285.7853190126920861851560.0993.80.292.373.381.4723.38.0710148.228750.25191187788581682270.0532.30.090.591.631.068.612.8535.216.777.613.513731.61171941937780.961320.736.5913.23.7045.712.914761.624938.937870.611439551472893.841672.1811.411.74.5351.917.221587.943782.78641871657241517589101.001180.839.1614.05.6557.618.419672.530855.758010372774111072111.1347.90.846.528.292.2133.89.8512954.024041.641289.5385133617901122.641562.0819.227.210.612231.634412755690.879614399889112897130.291511.1413.325.35.4094.926.229311449578.97521521350129514638142.034612.2318.229.210.412330.231313357581.7640117233295714226154.471261.5510.317.66.7851.214.218377.728746.5534121953132119386160.2381.01.0712.425.510.086.921.024795.438257.258612034439616506176.031952.319.0411.45.2354.914.415368.528538.233759.269137916054全巖60.494.49.0329.03.870.692.630.301.510.220.660.100.490.0822.94.354.69QEC-8(花崗斑巖)10.1874.20.9514.127.47.6472.021.925790.931952.153398.73872461222320.1469.80.222.074.951.8821.15.8078.537.118829.934078.33213801792330.0421.00.131.342.900.6311.52.9434.314.965.99.5686.717.235.680.718603410236531.310729.87.3051.813.714652.225646.949880.97809321311450.1120.70.638.0911.33.6742.310.210744.617729.925545.61141101268866.561331.478.8812.53.7052.915.520589.739660.65761255956271531473.7791.24.2817.79.542.6930.28.0598.342.422535.835977.845165215181845.319323.976.724.83.1154.112.514661.127241.639378.739782617922912537335.712632.46.1460.014.116372.431949.242690.6411446150051041.61429.7541.822.24.3255.216.120673.729149.950292.130532010863114.5184.21.6810.611.33.0745.813.416367.330956.251992.3427452129261229.51237.2129.615.02.0746.715.318666.128453.256592.0962126011256135.661104.2818.118.05.9251.313.514869.832452.854914173693822108140.1437.30.324.097.030.5830.29.2812448.622036.638075.530259214122150.5545.10.332.863.881.6019.66.0083.848.725545.4528145680147419242166.3278.52.1011.78.412.6928.48.4010944.021138.442898.6642103914575171.9574.31.3412.116.44.2172.420.622081.136161.457610047648913029180.5958.30.403.264.991.8626.68.3010444.422338.735566.033337014067193.6768.92.0210.910.33.1740.511.313758.627745.244493.272980914297205.1239.52.8216.517.80.6979.319.219272.833957.447177.633856215152全巖41.667.76.5321.03.080.562.300.341.760.290.850.140.920.1726.97.464.77

圖6 二長(zhǎng)花崗巖和花崗斑巖鋯石εHf(t)統(tǒng)計(jì)直方圖(a)和二階段模式年齡(tDM2)統(tǒng)計(jì)直方圖(b)Fig.6 Histogram of εHf(t) (a) and two stage mode ages (tDM2) (b) of zircons from monzogranite and granite porphyry

表4千鵝沖鉬礦二長(zhǎng)花崗巖和花崗斑巖鋯石Ce3+和Ce4+的分配系數(shù)及比值

Table 4 Partition coefficients and ratios of Ce3+and Ce4+of zircons from monzogranite and granite porphyry in the Qian’echong Mo deposit

測(cè)點(diǎn)號(hào)DCe3+DCe4+Ce4+/Ce3+Ce/Ce*Eu/Eu*QEC-7(二長(zhǎng)花崗巖)10.00070341.5393.7234.60.6320.00600803.5215.349.70.5030.00529720.2164.09.20.4340.00157847.4636.185.50.3950.01730896.380.610.30.4960.00062758.91606145.20.5170.00053384.2639.3115.10.8780.01533870.390.638.70.4690.00462999.4382.514.10.56100.01202739.6103.131.80.61110.00481584.7104.512.10.40120.03290823.749.416.40.57130.02630938.360.063.90.34140.046001103.9105.753.20.53150.01552808.585.311.80.69160.03346551.624.740.20.65170.01412708.2145.812.80.64QEC-8(花崗斑巖)10.15925541.95.943.70.5320.00648508.1158.498.20.5630.01032226.729.175.70.3340.21304652.224.51.60.5750.05883344.04.219.70.5160.02666617.872.910.50.4470.02364576.756.15.60.4980.15398521.417.61.40.2690.22445543.423.81.40.43100.11094483.717.91.70.38110.02921548.741.77.50.41120.05154745.434.42.10.24130.04518673.234.95.50.59140.01412490.238.042.90.12150.00213675.9311.325.90.56160.01469658.578.05.30.53170.05755584.118.111.30.37180.00824497.5103.629.50.49190.02369662.042.06.20.47200.08648499.75.72.50.06

注：鋯石和熔體之間Ce4+和Ce3+的分配系數(shù)DCe3+、DCe4+及Ce4+/Ce3+比值計(jì)算方法據(jù)Ballardetal. (2002)；Eu/Eu*=EuN/(SmN×GdN)1/2；Ce/Ce*=CeN/(LaN×PrN)1/2

圖7 鋯石稀土元素球粒隕石標(biāo)準(zhǔn)化配分曲線(xiàn)(球粒隕石標(biāo)準(zhǔn)化值據(jù)Sun and McDonough, 1989)Fig.7 Chondrite-normalized REE patterns of zircons (chondritite values after Sun and McDonough, 1989)

5.3 鋯石微量元素特征

鋯石中稀土元素及Th、U、Hf元素含量見(jiàn)表3。測(cè)試結(jié)果顯示，二長(zhǎng)花崗巖中鋯石的稀土總量為358.9×10-6～2536×10-6，平均為1604×10-6；花崗斑巖中鋯石的稀土總量為268.8×10-6～1893×10-6，平均為1279×10-6。鋯石稀土元素球粒隕石標(biāo)準(zhǔn)化配分曲線(xiàn)(圖7)顯示，二長(zhǎng)花崗巖和花崗斑巖具有較一致的稀土元素特征，虧損LREE且富集HREE。

鋯石Ce4+和Ce3+在鋯石-熔體間的分配系數(shù)DCe4+、DCe3+及Ce4+/Ce3+比值見(jiàn)表4。計(jì)算結(jié)果顯示，二長(zhǎng)花崗巖和花崗斑巖都具有變化較大的Ce4+/Ce3+比值，但二長(zhǎng)花崗巖總體上具有相對(duì)花崗斑巖更大的Ce4+/Ce3+比值。二長(zhǎng)花崗巖和花崗斑巖中的鋯石均顯示正Ce異常和Eu負(fù)異常(圖7)，但樣品Q(chēng)EC-8中部分鋯石具有更強(qiáng)負(fù)Eu異常(圖7b)，鋯石Ce/Ce*分別變化于9.2～234.6和1.4～98.2之間，Eu/Eu*變化范圍分別為0.34～0.87(平均0.55)和0.06～0.59(平均0.42)。

6 討論

6.1 成巖成礦時(shí)代

本次研究得到千鵝沖鉬礦中隱伏的二長(zhǎng)花崗巖和花崗斑巖SHRIMP鋯石U-Pb年齡分別為130±2Ma和129±2Ma，二者在誤差范圍內(nèi)一致。這一結(jié)果與李法嶺(2011)和楊梅珍等(2010)報(bào)道的千鵝沖鉬礦床的輝鉬礦Re-Os同位素年齡(128±7Ma)及成礦后花崗斑巖脈的年齡(129±3Ma)也具有比較好的一致性，說(shuō)明千鵝沖斑巖型鉬礦床的成巖成礦作用發(fā)生在早白堊世。

鑒于前人(李法嶺，2011；楊梅珍等，2010)報(bào)道的千鵝沖鉬礦輝鉬礦Re-Os等時(shí)線(xiàn)年齡誤差較大(±7Ma)，最近，作者運(yùn)用輝鉬礦Re-Os同位素定年重新厘定了千鵝沖鉬礦的成礦時(shí)代，6件輝鉬礦樣品得到了一條理想的等時(shí)線(xiàn)，其Re-Os等時(shí)線(xiàn)年齡為129±2Ma(MSWD=0.63)(數(shù)據(jù)待發(fā)表)。這一結(jié)果與本文獲得的千鵝沖礦區(qū)二長(zhǎng)花崗巖和花崗斑巖的SHRIMP鋯石U-Pb年齡非常一致，說(shuō)明千鵝沖鉬礦成巖成礦時(shí)限較短，約為128～130Ma。

近年來(lái)，東秦嶺-大別鉬礦帶鉬礦床年代學(xué)研究表明，雖然有少量鉬礦床形成于中生代以前(如寨凹和龍門(mén)店，李厚民等，2009；魏慶國(guó)等，2009)，但總體上以中生代成礦作用大爆發(fā)為顯著特征(李永峰等，2005；毛景文等，2005；葉會(huì)壽等，2006)。Maoetal.(2008，2011a)比較全面地統(tǒng)計(jì)了東秦嶺-大別鉬礦帶鉬礦床成礦時(shí)代，將中生代鉬礦床作用劃分為三個(gè)期次：晚三疊(221～233Ma)、晚侏羅-早白堊(138～148Ma)、早-中白堊(112～131Ma)。與東秦嶺多期次鉬成礦作用不同，除個(gè)別侏羅紀(jì)年齡外，絕大多數(shù)大別山地區(qū)鉬礦床的成礦作用發(fā)生于早白堊世(黃凡等，2011；李毅等，2013，及其中引文)，此時(shí)代跨度與大別山碰撞后巖漿作用時(shí)限基本一致(Heetal., 2011；Wangetal., 2007)。

6.2 巖漿源區(qū)及相對(duì)氧逸度

6.2.1 巖漿源區(qū)

鋯石Lu-Hf同位素體系具有較高的封閉溫度(Schereretal., 2000)，能有效地揭示巖漿演化過(guò)程和源區(qū)性質(zhì)(Griffinetal., 2000；Beloisovaetal., 2006)。由于Hf屬于不相容元素，當(dāng)寄主巖漿不斷發(fā)生部分熔融和結(jié)晶分異作用時(shí)，虧損地幔源區(qū)具有更高的176Hf/177Hf比值，使得熔融物和寄主巖漿發(fā)生176Hf/177Hf比值的解耦，即大陸地殼相對(duì)于虧損地幔具有更低的176Hf/177Hf比值和εHf(t)值(Patchettetal., 1981)。

表2和圖8顯示，千鵝沖鉬礦中二長(zhǎng)花崗巖和花崗斑巖中的鋯石具有低的εHf(t)值和古老的Hf模式年齡，并且所有Hf同位素?cái)?shù)據(jù)點(diǎn)均落于球粒隕石Hf同位素演化線(xiàn)之下(圖8)，表明千鵝沖巖體主要來(lái)源于古老的地殼物質(zhì)。大別造山帶的深部地殼和巖石圈地幔是否存在華北物質(zhì)存在爭(zhēng)議(Huangetal., 2007；Li and Yang, 2003；Wangetal., 2005)，但基于對(duì)大別造山帶超高壓變質(zhì)巖及早白堊世高Sr/Y花崗巖的地球化學(xué)性質(zhì)的詳細(xì)研究，多數(shù)學(xué)者認(rèn)為大別造山帶的地殼物質(zhì)基本來(lái)自華南板塊(Heetal., 2013；Zhengetal., 2003；Zheng and Zhang, 2007；Zhaoetal., 2007；Zhao and Zheng, 2009)。所以千鵝沖花崗巖應(yīng)來(lái)源于華南板塊北緣的古老地殼。

圖8 鋯石εHf(t)-Age圖解資料來(lái)源：北大別片麻巖引自Zhao et al. (2008)；太古代崆嶺片麻巖和混合巖以及古元古代崆嶺花崗巖引自Zhang et al. (2006)，Zheng et al. (2006)，Xiong et al. (2008)；虧損地幔演化線(xiàn)據(jù)Nowell et al. (1998)Fig.8 εHf(t) vs. Age plots for zirconsData sources: The granitic gneiss from North Dabie from Zhao et al. (2008); Archean gneiss and migmatite and Paleoproterozic granite from the Kongling Complex from Zhang et al. (2006a); Zheng et al. (2006b); Xiong et al. (2008). The evolutionary line of depleted mantle after Nowell et al. (1998)

千鵝沖花崗巖的鋯石Hf同位素特征與大別造山帶碰撞后花崗巖的鋯石Hf同位素特征具有相似性(Zhaoetal., 2011)，暗示它們具有一致的來(lái)源。對(duì)大別造山帶內(nèi)碰撞后花崗巖類(lèi)的研究表明，它們與造山帶地表出露的原巖為新元古代的雙峰式火成巖的高壓-超高壓變質(zhì)巖(Liu and Xue, 2007；Zhengetal., 2003)有相似的地球化學(xué)特征(Bryantetal., 2004；Heetal., 2011, 2013；Wangetal., 2007；Zhangetal., 2002；Zhaoetal., 2011)，說(shuō)明這些花崗巖來(lái)自大別造山帶高壓-超高壓變質(zhì)巖的部分熔融(Heetal., 2013；Wangetal., 2007；Zhaoetal., 2011)。雖然對(duì)于大別造山帶后碰撞花崗巖具體來(lái)自鎂鐵質(zhì)榴輝巖還是中酸性大別片麻巖存在較大分歧(Heetal., 2011, 2013；Wangetal., 2007；Zhaoetal., 2011；Xuetal., 2013)，但是古元古-太古代的繼承鋯石、古元古-太古代的Nd和Hf的模式年齡都指示這些花崗巖的原巖混入了不同比例的更古老的地殼物質(zhì)(如太古代崆嶺雜巖)(Heetal., 2013；Zhaoetal., 2011)。千鵝沖花崗斑巖中發(fā)現(xiàn)了年齡為1943Ma的古元古代繼承鋯石，其與崆嶺雜巖內(nèi)的古元古代花崗巖具有相似的Hf同位素特征(圖8)，也說(shuō)明了其原巖混入了類(lèi)似崆嶺雜巖的古老地殼物質(zhì)。雖然兩個(gè)樣品中大部分鋯石的εHf(t)值為較低的負(fù)值，但是變化范圍較大的εHf(t)值和二階段模式年齡暗示其源區(qū)可能混入了不同比例的年輕地幔組分，尤其是二長(zhǎng)花崗巖(圖6)。大別山地區(qū)白堊紀(jì)超基性巖漿作用開(kāi)始于～130Ma(Jahnetal., 1999；Wangetal., 2005)，說(shuō)明此時(shí)地幔上涌不僅為花崗巖原巖部分熔融提供了熱源，也注入了少量幔源組分。

6.2.2 相對(duì)氧逸度

實(shí)驗(yàn)表明，Mo在流體中的溶解度與流體的氧逸度關(guān)系密切(Balietal., 2012)。巖漿中的Ce常呈3價(jià)和4價(jià)，在氧化條件下，鋯石中的Zr4+容易被Ce4+離子取代。另外，Ce3+和Ce4+的分異能力很強(qiáng)，對(duì)巖漿的氧化還原狀態(tài)具有較高的敏感度，因此可以通過(guò)Ce4+/Ce3+比值來(lái)判斷巖漿氧逸度的相對(duì)高低(Ballardetal., 2002；Bolharetal., 2008；Burnham and Berry, 2012；Trailetal., 2012)。Eu在巖漿中呈Eu2+和Eu3+兩種價(jià)態(tài)，當(dāng)Ce4+穩(wěn)定存在時(shí)，Eu應(yīng)呈三價(jià)。實(shí)驗(yàn)表明，Eu的異常一般與Ce的異常呈正相關(guān)關(guān)系，并且也可用來(lái)指示熔體的氧逸度(Burnham and Berry, 2012；Trailetal., 2012)。

千鵝沖鉬礦花崗斑巖中的鋯石比二長(zhǎng)花崗巖中的鋯石具有更低的Eu/Eu*比值，即更強(qiáng)的Eu異常，可能是由于斜長(zhǎng)石的分離結(jié)晶作用(Hoskin and Schaltegger, 2003)。隨著巖漿的演化，在鋯石達(dá)到飽和之前，Eu2+優(yōu)先進(jìn)入斜長(zhǎng)石，從而造成了演化程度更高的花崗斑巖中的鋯石具有更強(qiáng)的Eu異常。二長(zhǎng)花崗巖和花崗斑巖中的鋯石的Ce4+/Ce3+比值平均值分別為287.4和55.9。二長(zhǎng)花崗巖中的鋯石中具有較高的Ce4+/Ce3+比值，與西藏玉龍和岡底斯地區(qū)以及智利東部的斑巖銅礦具有相似的特征(Ballardetal., 2002；Liangetal., 2006；辛洪波和曲曉明，2008)，相比之下，花崗斑巖中鋯石的Ce4+/Ce3+比值明顯低于這些斑巖銅礦。鉆孔中揭露的花崗斑巖遠(yuǎn)多與二長(zhǎng)花崗巖且形成晚于二長(zhǎng)花崗巖，推測(cè)成礦流體更可能來(lái)自花崗斑巖。已有研究表明，巖漿的氧逸度不是控制鉬成礦的決定因素，巖漿中鐵和鈦的含量、巖漿流體含量以及巖漿上升過(guò)程中的對(duì)流機(jī)制都是影響鉬富集的重要因素(Keppler and Wyllie, 1991；Shinogaraetal., 1995；Tacker and Candela, 1987)。

6.3 動(dòng)力學(xué)背景

大別造山帶形成于三疊紀(jì)華南與華北板塊之間的碰撞對(duì)接(Lietal., 1993；Hackeretal., 1998)，關(guān)于造山帶內(nèi)含柯石英和金剛石的超高壓變質(zhì)巖的研究顯示大量的華南陸殼物質(zhì)曾深俯沖到超過(guò)100km的深度(Wangetal., 1989)。然而，地震資料表明該造山帶現(xiàn)今地殼的平均厚度約為35km，且缺少基性下地殼，暗示曾經(jīng)發(fā)生了加厚山根的拆沉作用(Gaoetal., 1998a, b)。

大別造山帶發(fā)育的大量白堊紀(jì)花崗巖在約130Ma發(fā)生明顯的地球化學(xué)特征變化，即>130Ma形成的花崗巖具有高Sr/Y和(La/Yb)N比值以及低Y含量的特征，而形成于130Ma之后的花崗巖則不具備這一特征(Heetal., 2011；Wangetal., 2007)。研究表明，早期花崗巖(130～143Ma)來(lái)自石榴石為主要?dú)埩粝嗟募雍裣碌貧さ牟糠秩廴?Heetal., 2011)?；◢弾r地球化學(xué)特征在130Ma左右發(fā)生的轉(zhuǎn)變指示大別造山帶在約130Ma發(fā)生了下地殼的拆沉作用，所以之后形成的花崗巖來(lái)自減薄地殼的部分熔融(Heetal., 2011；Wangetal., 2007；Xuetal., 2007)。另外，北大別廣泛分布的形成于123～130Ma的鎂鐵-超鎂鐵質(zhì)巖的地球化學(xué)特征顯示，它們具有明顯的陸殼物質(zhì)特征屬性，可能由拆沉的下地殼熔體交代上地幔或巖石圈地幔形成(Huangetal., 2007)。所以，大別造山帶在早白堊世發(fā)生了下地殼的拆沉作用(Gaoetal., 1998a, b)。

碰撞造山帶的演化一般都要經(jīng)歷從擠壓縮短向伸展減薄的構(gòu)造體制的轉(zhuǎn)換過(guò)程(Leech, 2001；Vanderhaeghe and Teyssier, 2001)。大別造山帶早白堊世下地殼拆沉作用可能導(dǎo)致造山帶的去山根作用、軟流圈上涌及大規(guī)模地殼伸展(Ratschbacheretal., 2000, 2003；Bryantetal., 2004；Hackeretal., 2004；Liuetal., 2004)。Wuetal.(2007)通過(guò)對(duì)北大別混合巖的研究認(rèn)為，大別山地區(qū)構(gòu)造體制由擠壓向伸展轉(zhuǎn)換的時(shí)間約為145Ma。另外，大別造山帶于早白堊世侵位的A型花崗巖也進(jìn)一步證明了當(dāng)時(shí)的伸展環(huán)境(王強(qiáng)等，2000；謝智等，2004)。

綜上所述，千鵝沖鉬礦的成巖成礦作用發(fā)生在大別山地區(qū)早白堊世的伸展構(gòu)造背景下。事實(shí)上，整個(gè)中國(guó)東部在早白堊世總體處在伸展的構(gòu)造體制下(Maoetal., 2011b；Wangetal., 2012)。在這一時(shí)期，不僅形成了東秦嶺-大別鉬礦帶這一世界級(jí)鉬多金屬成礦省(Maoetal., 2008, 2011a)，而且在中國(guó)東北地區(qū)(Yangetal. 2003；孫景貴等，2012)、華北克拉通內(nèi)部(翟明國(guó)，2010；毛景文等，2005)、長(zhǎng)江中下游地區(qū)(Duanetal., 2012；Maoetal., 2011c；Xieetal., 2008, 2011, 2012；袁順達(dá)等，2010)以及華南地區(qū)(Maoetal., 2013)均發(fā)育了大規(guī)模的構(gòu)造-巖漿-成礦事件(Maoetal., 2011b；Wangetal., 2012；Wuetal., 2005)，它們均與中國(guó)東部乃至亞洲東北部晚中生代大規(guī)模地殼伸展的構(gòu)造背景密切相關(guān)(Maoetal., 2003；Wangetal., 2012)。

7 結(jié)論

(1)千鵝沖鉬礦區(qū)隱伏巖體中的二長(zhǎng)花崗巖和花崗斑巖的SHRIMP鋯石U-Pb年齡分別為130±2Ma和129±2Ma，與輝鉬礦Re-Os年齡一致，為早白堊世，成巖成礦作用發(fā)生在一個(gè)很短的時(shí)限內(nèi)(128～130Ma)。

(2)鋯石Hf同位素特征顯示千鵝沖巖體的物質(zhì)來(lái)源主要為華南陸塊北緣的古老地殼及少量年輕地幔組分，原巖中含有古元古代-太古代的基底巖石，二長(zhǎng)花崗巖相比花崗斑巖具有更高的氧逸度。

(3)千鵝沖鉬礦床形成于早白堊世的伸展構(gòu)造體制下。大別造山帶于早白堊世發(fā)生的下地殼拆沉作用導(dǎo)致的軟流圈上涌及殼幔相互作用不僅形成了大規(guī)模的巖漿作用，也為斑巖型鉬礦床提供了物質(zhì)來(lái)源。

致謝中國(guó)地質(zhì)科學(xué)院地質(zhì)研究所劉建輝、礦產(chǎn)資源研究所郭春麗和國(guó)家地質(zhì)實(shí)驗(yàn)測(cè)試中心孫東陽(yáng)分別在SHRIMP鋯石測(cè)年、鋯石Hf同位素測(cè)試及鋯石微量元素測(cè)試過(guò)程中提供了大量幫助，在此一并表示感謝。

Bali E, Keppler H and Audetat A. 2012. The mobility of W and Mo in subduction zone fluids and the Mo-W-Th-U systematics of island arc magmas. Earth and Planetary Science Letters, 351-352: 195-207

Ballard J, Palin M and Campbell I. 2002. Relative oxidation states of magmas inferred from Ce(IV)/Ce(III) in zircon: Application to porphyry copper deposits of northern Chile. Contributions to Mineralogy and Petrology, 144(3): 347-364

Beloisova BA, Griffin WL and O’Reilly SY. 2006. Zircon crystal morphology, trace element signatures and Hf Isotope composition as a tool for petrogenetic modeling: Examples from Eastern Australian granitoids. Journal of Petrology, 47(2): 329-353

Belousova EA, Griffin WL, O’Reilly SY and Fisher NI. 2002. Igneous zircon: Trace element composition as an indicator of source rock type. Contributions to Mineralogy and Petrology, 143(5): 602-622

Blichert-Toft J and Albarède F. 1997. The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system. Earth and Planetary Science Letters, 148: 243-258

Bolhar R, Weaver SD, Palin JM, Cole JW and Paterson LA. 2008. Systematics of zircon crystallisation in the Cretaceous separation point suite, New Zealand, using U-Pb isotopes, REE and Ti geothermometry. Contributions to Mineralogy Petrology, 156(2): 133-160

Bryant DL, Ayers JC, Gao S, Miller CF and Zhang H. 2004. Geochemical, age, and isotopic constraints on the location of the Sino-Korean-Yangtze suture and evolution of the northern Dabie complex, east central China. Geological Society of America Bulletin, 116(5-6): 698-717

Burnham, AD and Berry AJ. 2012. An experimental study of trace element partitioning between zircon and melt as a function of oxygen fugacity. Geochimica et Cosmochimica Acta, 95: 196-212

Chen FK, Guo JH, Jiang LL, Siebel W, Cong BL and Satir M. 2003. Provenance of the Beihuaiyang lower-grade metamorphic zone of the Dabie ultrahigh-pressure collisional orogen, China: Evidence from zircon ages. Journal of Asian Earth Sciences, 22(4): 343-352

Dai LQ, Zhao ZF, Zheng YF, Li QL, Yang YH and Dai MN. 2011. Zircon Hf-O isotope evidence for crust-mantle interaction during continental deep subduction. Earth and Planetary Science Letters, 308(1): 229-244

Duan C, Li YH, Hou KJ, Yuan SD, Liu JL and Zhang C. 2012. Late Mesozoic ore-forming events in the Ningwu ore district, middle-lower Yangtze River polymetallic ore belt, East China: Evidence from zircon U-Pb geochronology and Hf isotopic compositions of the granodioritic stocks. Acta Geologica Sinica, 86(3): 719-736

Elhlou S, Belousova E, Griffin WL, Pearson NJ and O’reilly SY. 2006. Trace element and isotopic composition of GJ-red zircon standard by laser ablation. Geochimica et Cosmochimica Acta, 70(18): A158

Fan WM, Guo F, Wang YJ and Zhang M. 2004. Late Mesozoic volcanism in the northern Huaiyang tectono-magmatic belt, central China: Partial melts from a lithospheric mantle with subducted continental crust relicts beneath the Dabie orogen? Chemical Geology, 209(1-2): 27-48

Gao S, Luo TC, Zhang BR, Zhang HF, Han YM, Zhao ZD and Hu YK. 1998a. Chemical composition of the continental crust as revealed by studies in East China. Geochimica et Cosmochimica Acta, 62(11): 1959-1975

Gao S, Zhang BR, Jin ZM, Kern H, Zhao ZD and Luo TC. 1998b. How mafic is the lower continental crust? Earth and Planetary Science Letters, 161(1): 101-117

Griffin WL, Pearson NJ, Belousova E, Jackson SE, Achterbergh EV, O’Reilly SY and Shee SR. 2000. The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites. Geochimica et Cosmochimica Acta, 64(1): 133-147

Hacker BR, Ratschbacher L, Webb L, Ireland T, Walker D and Dong SW. 1998. U-Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling-Dabie Orogen, China. Earth and Planetary Science Letters, 161(1-4): 215-230

Hacker BR, Ratshbacher L, Webb LE, Ireland TR, Calvert A, Dong S, Wenk HR and Chateigner D. 2000. Exhumation of ultrahigh-pressure continental crust in east-central China: Late Triassic-Early Jurassic tectonic unroofing. Journal of Geophysical Research, 105(B6): 13339-13364

Hacker BR, Ratschbacher L and Liu JG. 2004. Subduction, collision and exhumation in the ultrahigh-pressure Qinling-Dabie orogen. In: Malpas J, Fletcher C and Ali JR (eds.). Aspects of the Tectonic Evolution of China, Vol. 226. Geological Society, Special Publication, London, 157-175

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

He YS, Li SG, Hoefs J and Kleinhanns IC. 2013. Sr-Nd-Pb isotopic compositions of Early Cretaceous granitoids from the Dabie orogen: Constraints on the recycled lower continental crust. Lithos, 156-159: 204-217

Hoskin PWO and Schaltegger U. 2003. The composition of zircon and igneous and metamorphic petrogenesis. Reviews in Mineralogy and Geochemistry, 53: 27-62

Hou KJ, Li YH, Zou TR, Qu XM, Shi YR and Xie GQ. 2007. Laser ablation-MC-ICP-MS technique for Hf isotope microanalysis of zircon and its geological applications. Acta Petrologica Sinica, 23(10): 2595-2604 (in Chinese with English abstract)

Huang F, Li SG, Dong F, Li QL, Chen FK, Wang Y and Yang W. 2007. Recycling of deeply subducted continental crust in the Dabie Mountains, central China. Lithos, 96(1-2): 151-169

Huang F, Li SG, Dong F, He YS and Chen FK. 2008. High-Mg adakitic rocks in the Dabie orogen, central China: Implications for foundering mechanism of lower continental crust. Chemical Geology, 255(1-2): 1-13

Huang F, Wang DH, Lu SM, Chen YC, Wang BH and Li C. 2011. Molybdenite Re-Os isotopic age of Shapinggou Mo deposit in Anhui Province and Mesozoic Mo ore-forming stages in East Qinling-Dabie Mountain region. Mineral Deposits, 30(6): 1039-1057 (in Chinese with English abstract)

Jahn BM, Wu FY, Lo CH and Tsai CH. 1999. Crust-mantle interaction induced by deep subduction of the continental crust: Geochemical and Sr-Nd isotopic evidence from post-collisional mafic-ultramafic intrusions of the northern Dabie complex, central China. Chemical Geology, 157(1-2): 119-146

Keppler H and Wyllie PJ. 1991. Partitioning of Cu, Sn, Mo, W, U, and Th between melt and aqueous fluid in systems halpogranite-H2O-HCl and halogranite-H2O-HF. Contributions to Mineralogy and Petrology, 109(2): 139-150

Leech ML. 2001. Arrested orogenic development: Eclogitization, delamination, and tectonic collapse. Earth and Planetary Science Letters, 185(1-2): 149-159

Li FL. 2011. Geological characteristics and metallogenic epoch of Qianechong large-size porphyry mo deposit at the northern foot of Dabie Mountains, He’nan Province. Mineral Deposits, 30(3): 457-468 (in Chinese with English abstract)

Li HM, Ye HS, Wang DH, Chen YC, Qu WJ and Du AD. 2009. Re-Os dating of molybdenites from Zhaiwa Mo deposit in Xiong’er Mountain, western Henan Province, and its geological significance. Mineral Deposits, 28(2): 133-142 (in Chinese with English abstract)

Li SG, Xiao YL, Liou DL, Chen YZ, Ge NJ, Zhang ZQ, Sun SS, Cong BL, Zhang RY, Hart SR and Wang SS. 1993. Collision of the North China and Yangtze blocks and formation of coesite-bearing eclogites-timing and processes. Chemical Geology, 109(1-4): 89-111

Li SG, Huang F, Nie YH, Han WL, Long G, Li HM, Zhang SQ and Zhang ZH. 2001. Geochemical and geochronological constraints on the suture location between the North and South China blocks in the Dabie orogen, central China. Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 26(9-10): 655-672

Li SG and Yang W. 2003. Decoupling of surface and subsurface sutures in the Dabie orogen and a continent-collisional lithospheric-wedging model: Sr-Nd-Pb isotopic evidences of Mesozoic igneous rocks in eastern China. Chinese Science Bulletin, 48(8): 831-838

Li Y, Li N, Yang YF, Wang P, Mi M, Zhang J, Chen HJ and Chen YJ. 2013. Geological features and geodynamic settings of the Mo deposits in the northern segment of the Dabie Mountains. Acta Petrologica Sinica, 29(1): 95-106 (in Chinese with English abstract)

Li YF, Mao JW, Hu HB, Guo BJ and Bai FJ. 2005. Geology, distribution, types and tectonic settings of Mesozoic molybdenum deposits in East Qinling area. Mineral Deposits, 24(3): 292-304 (in Chinese with English abstract)

Liang HY, Camplel HI, Allen C, Sun WD, Liu CQ, Yu HX, Xie YW and Zhang YQ. 2006. Zircon Ce4+/Ce3+ratios and ages for Yulong ore-bearing porphyries in eastern Tibet. Mineralium Deposita, 41(2): 152-159

Liu FL and Xue HM. 2007. Review and prospect of SHRIMP U-Pb dating on zircons from Sulu-Dabie UHP metamorphic rocks. Acta Petrologica Sinica, 23(11): 2737-2756 (in Chinese with English abstract)

Liu XC, Jahn BM, Liu DY, Dong SW and Li SZ. 2004. SHRIMP U-Pb zircon dating of a metagabbro and eclogites from western Dabieshan (Hong’an Block), China, and its tectonic implications. Tectonophysics, 394: 171-192

Liu YC, Li SG, Xu ST, Jahn BM, Zheng YF, Zhang ZQ, Jiang LL, Chen GB and Wu WP. 2005. Geochemistry and geochronology of eclogites from the Northern Dabie Mountains, central China. Journal of Asian Earth Sciences, 25: 431-443

Ludwig K. 2003. User’s manual for Isoplot 3.00: A geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication, 4: 70

Mao JW, Zhang ZH, Yu JJ and Niu BG. 2003. Geodynamic settings of Mesozoic large-scale mineralization in North China and adjacent areas: Implication from the highly precise dating of ore deposits. Science China (Series D) 46(8): 838-851

Mao JW, Xie GQ, Zhang ZH, Li XF, Wang YT, Zhang CQ and Li YF. 2005. Mesozoic large scale metallogenic pulses in North China and corresponding geodynamic settings. Acta Petrologica Sinica, 21(1): 169-188 (in Chinese with English abstract)

Mao JW, Xie GQ, Bierlein F, Qu WJ, Du AD, Ye HS, Pirajno F, Li HM, Guo BJ, Li YF and Yang ZQ. 2008. Tectonic implications from Re-Os dating of Mesozoic molybdenum deposits in the East Qinling-Dabie orogenic belt. Geochimica et Cosmochimica Acta, 72(18): 4607-4626

Mao JW, Pirajno F, Xiang JF, Gao JJ, Ye HS, Li YF and Guo BJ. 2011a. Mesozoic molybdenum deposits in the East Qinling-Dabie Orogenic belt: Characteristics and tectonic settings. Ore Geology Reviews, 43(1): 264-293

Mao JW, Pirajno F and Cook N. 2011b. Mesozoic metallogeny in East China and corresponding geodynamic settings: An introduction to the special issue. Ore Geology Reviews, 43(1): 1-7

Mao JW, Xie GQ, Duan C, Pirajno F, Ishiyama D and Chen YC. 2011c. A tectono-genetic model for porphyry-skarn-stratabound Cu-Au-Mo-Fe andmagnetite-apatite deposits along Middle-Lower Yangtze River Valley, eastern China. Ore Geology Reviews, 43(1): 294-314

Mao JW, Cheng YB, Chen MH and Pirajno F. 2013. Major types and time-space distribution of Mesozoic ore deposits in South China and their geodynamic settings. Mineralium Deposita, 48(3): 267-294

Nowell GM, Kempton PD, Noble SR, Fitton JG, Saunders AD, Mahoney JJ and Tayloy RN. 1998. High precision Hf isotope measurements of MORB and OIB by thermal ionization mass spectronmetry: Insights into the depleted mantle. Chemical Geology, 149(3-4): 211-233

Patchett PJ, Kouvo O, Hedge CE and Tatsumoto M. 1981. Evolution of continental crust and mantle heterogeneity: Evidence from Hf isotopes. Contributions to Mineralogy Petrology, 78(3): 279-297

Ratschbacher L, Hacker BR, Webb LE, McWilliams M, Ireland T, Dong SW, Calvert A, Chateigner D and Wenk HR. 2000. Exhumation of the ultrahigh-pressure continental crust in east central China: Cretaceous and Cenozoic unroofing and the Tan-Lu fault. Journal of Geophysical Research, 105(B6): 13303-13338

Ratschbacher L, Hacker BR, Calvert A, Webb LE, Grimmer JC, Mcwilliams MO, Ireland T, Dong S and Hu J. 2003. Tectonics of the Qinling (Central China): Tectonostratigraphy, geochronology, and deformation history. Tectonophysics, 366(1-2): 1-53

Rubatto D and Gebauer D. 2000. Use of cathodoluminescence for U-Pb zircon dating by IOM microprobe: Some examples from the western Alps. In: Cathodoluminescence in Geoscience. Heidelberg, Germany: Springer-Verlag, 373-400

Scherer EE, Cameron KL and Blichert JT. 2000. Lu-Hf garnet geochronology: Closure temperature relative to the Sm-Nd system and the effects of trace mineral inclusions. Geochimica et Cosmochimica Acta, 64(19): 3413-3432

Shinogara H, Kazahaya K and Lowenstern JB. 1995. Volatile transport in a convecting magma column: Implications for porphyry Mo mineralization. Geology, 23(12): 1091-1094

Soderlund U, Patchett PJ, Vervoort JD and Isachsen CE. 2004. The176Lu decay constant determined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusions. Earth and Planetary Science Letters, 219(3-4): 311-324

Sun JG, Zhang Y, Xing SW, Zhao KQ, Zhang ZJ, Bai LA, Ma YB and Liu YS. 2012. Genetic types, ore-forming age and geodynamic setting of endogenetic molybdenum deposits in the eastern edge of Xing-Meng orogenic belt. Acta Petrologica Sinica, 28(4): 1317-1332 (in Chinese with English abstract)

Sun SS and McDonoung 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): 315-345

Tacker RC and Candela PA. 1987. Partitioning of molybdenum between magnetite and melt: A preliminary experimental study of partitioning of ore metals between silicic magmas and crystalline phases. Economic Geology, 82(7): 1805-1826

Trail D, Bruce Watson E and Tailby ND. 2012. Ce and Eu anomalies in zircon as proxies for the oxidation state of magmas. Geochimica et Cosmochimica Acta, 97: 70-87

Vanderhaeghe O and Teyssier C. 2001. Partial melting and flow of orogens. Tectonophysics, 342(3-4): 451-472

Wang Q, Zhao Z and Xiong X. 2000. The ascertainment of Late-Yanshanian A-type granite in Tongbai-Dabie Orogenic Belt. Acta Petrologica et Mineralogica, 19(4): 297-306 (in Chinese with English abstract)

Wang Q, Wyman DA, Xu JF, Jian P, Zhao ZH, Li CF, Xu W, Ma JL and He B. 2007. Early Cretaceous adakitic granites in the Northern Dabie Complex, central China: Implications for partial melting and delamination of thickened lower crust. Geochimica et Cosmochimica Acta, 71(10): 2609-2636

Wang T, Guo L, Zheng YD, Donskaya T, Gladkochub D, Zeng LS, Li JB, Wang YB and Mazukabzov A. 2012. Timing and processes of late Mesozoic mid-lower-crustal extension in continental NE Asia and implications for the tectonic setting of the destruction of the North China Craton: Mainly constrained by zircon U-Pb ages from metamorphic core complexes. Lithos, 154: 315-345

Wang XM, Liou JG and Mao HK. 1989. Coesite-bearing eclogite from the Dabie Mountains in Central China. Geology, 17(12): 1085-1088

Wang YJ, Fan WM, Peng TP, Zhang HF and Guo F. 2005. Nature of the Mesozoic lithospheric mantle and tectonic decoupling beneath the Dabie orogen, Central China: Evidence from40Ar/39Ar geochronology, elemental and Sr-Nd-Pb isotopic compositions of early Cretaceous mafic igneous rocks. Chemical Geology, 220(3-4): 165-189

Wei GQ, Yao JM, Zhao TP, Sun YL, Li J, Yuan ZL and Qiao B. 2009. Discovery of ～1.9Ga Mo deposit in the East Qinling orogen: Molybdenite Re-Os ages of the Longmendian Mo deposit in the Henan Province. Acta Petrologica Sinica, 25(11): 2747-2751 (in Chinese with English abstract)

Williams IS. 1998. U-Th-Pb geochronology by ion microprobe. In: McKibben MA, Shanks WC III and Ridley WI (eds.). Applications of Microanalytical Techniques to Understanding Mineralizing Processes. Reviews in Economic Geology, 7: 1-35

Wu FY, Lin JQ, Simon A, Wilde SA, Zhang XO and Yang JH. 2005. Nature and significance of the Early Cretaceous giant igneous event in eastern China. Earth Planetary Science Letters, 233(1-2): 103-119

Wu YB, Zheng YF, Zhang SB, Zhao ZF, Wu FY and Liu XM. 2007. Zircon U-Pb ages and Hf isotope compositions of migmatite from the North Dabie terrane in China: Constraints on partial melting. Journal of Metamorphic Geology, 25(9): 991-1009

Xiang BW. 2009. Research on the structural thermochronology and deformation modeling for post-orogenic dome structures of the north Dabie. Ph. D. Dissertation. Hefei: Hefei University of Technology (in Chinese with English summary)

Xie GQ, Mao JW, Li RL and Bierlein FP. 2008. Geochemistry and Nd-Sr isotopic studies of Late Mesozoic granitoids in the southeastern Hubei Province, Middle-Lower Yangtze River belt, eastern China: Petrogenesis and tectonic setting. Lithos, 104(1-4): 216-230

Xie GQ, Mao JW and Zhao HJ. 2011. Zircon U-Pb geochronological and Hf isotopic constraints on petrogenesis of Late Mesozoic intrusions in the southeast Hubei Province, Middle-Lower Yangtze River belt (MLYRB), East China. Lithos, 125(1-2): 693-710

Xie GQ, Mao JW, Zhao HJ, Duan C and Yao L. 2012. Zircon U-Pb and phlogopite40Ar-39Ar age of the Chengchao and Jinshandian skarn Fe deposits, Southeast Hubei Province, Middle-Lower Yangtze River valley metallogenic belt, China. Mineralium Deposita, 47(6): 633-652

Xie Z, Zheng YF, Yan J and Qian H. 2004. Source evolution relationship between A-type granites and mafic rocks from Shacun in Dabieshan. Acta Petrologica Sinica, 20(5): 1175-1184 (in Chinese with English abstract)

Xin HB and Qu XM. 2008. Relative oxidation states of ore-bearing porphyries inferred from Ce(IV)/Ce(III) ratio in zircon: Application to the porphyry copper belt at Gangense, Tibet. Acta Mineralogica Sinica, 28(2): 152-160 (in Chinese with English abstract)

Xiong Q, Zheng JP, Yu CM, Su YP, Tang HY and Zhang ZH. 2008. Zircon U-Pb age and Hf isotope of Quanyishang A-type granite in Yichang: Signification for the Yangtze continental cratonization in Paleoproterozoic. Chinese Science Bulletin, 54(3): 436-446

Xu HJ, Ma CQ and Ye K. 2007. Early Cretaceous granitoids and their implications for the collapse of the Dabie orogen, eastern China: SHRIMP zircon U-Pb dating and geochemistry. Chemical Geology, 240(3-4): 238-259

Xu HJ, Ma CQ, Zhang J and Ye K. 2013. Early Cretaceous low-Mg adakitic granites from the Dabie orogen, eastern China: Petrogenesis and implications for destruction of the over-thickened lower continental crust. Gondwana Research, 23(1): 190-207

Xu ST, Su W and Liu YC. 2000. Discovery of the eclogite and its petrography in the northern Dabie Mountain. Chinese Science Bulletin, 45(3): 273-278

Xu ST, Liu Y, Chen G, Roberto C, France R, He M and Liu H. 2003. New finding of micro-diamonds in eclogites from Dabie-Sulu region in central-eastern China. Chinese Science Bulletin, 48(10): 988-994

Yang JH, Wu FY and Wilde SA. 2003. A review of the geodynamic setting of large-scale Late Mesozoic gold mineralization in the North China Craton: An association with lithospheric thinning. Ore Geology Reviews, 23(3-4): 125-152

Yang MZ, Zeng JN, Qin YJ, Li FL and Wan SQ. 2010. LA-ICP-MS zircon U-Pb and molybdenite Re-Os dating for Qian’echong porphyry-type Mo deposit in northern Dabie, China, and its geological significance. Geological Science and Technology Information, 29(5): 35-45 (in Chinese with English abstract)

Yang YF, Chen YJ, Li N, Mi M, Xu YL, Li FL and Wan SQ. 2013. Fluid inclusion and isotope geochemistry of the Qian’echong giant porphyry Mo deposit, Dabie Shan, China: A case of NaCl-poor, CO2-rich fluid systems. Journal of Geochemical Exploration, 124: 1-13

Ye HS, Mao JW, Li YF, Guo BJ, Zhang CQ, Liu J, Yan QR and Liu GY. 2006. SHRIMP zircon U-Pb and molybdenite Re-Os dating for the superlarge Donggou porphyry Mo deposit in East Qinling, China, and its geological implication. Acta Geologica Sinica, 80(7): 1078-1088 (in Chinese with English abstract)

You ZD, Han YJ, Yang WR, Zhang ZM, Wei BZ and Liu R. 1996. The High-Pressure and Ultra High-Pressure Metamorphic Belt in the East Qinling and Dabie Mountains, China. Wuhan: China University of Geosciences Press, 1-150

Yuan SD, Hou KJ and Liu M. 2010. Timing of mineralization and geodynamic framework of iron-oxid-apatite deposits in Ningwu Cretaceous basin in the Middle-Lower Reaches of the Yangtze River, China: Constraints from Ar-Ar dating on phlogopites. Acta Petrologica Sinica, 26(3): 797-808 (in Chinese with English abstract)

Zhai MG. 2010. Tectonic evolution and metallogenesis of North China Craton. Mineral Deposits, 29(1): 24-36 (in Chinese with English abstract)

Zhang GW, Zhang BR, Yuan XC and Xiao QH. 2001. Qinling Belt and Continental Dynamics. Beijing: Science Press, 1-729 (in Chinese)

Zhang H, Gao S, Zhong Z, Zhang B, Zhang L and Hu S. 2002. Geochemical and Sr-Nd-Pb isotopic compositions of Cretaceous granitoids: Constraints on tectonic framework and crustal structure of the Dabieshan ultrahigh-pressure metamorphic belt, China. Chemical Geology, 186(3-4): 281-299

Zhang SB, Zheng YF, Wu YB, Zhao ZF, Gao S and Wu FY. 2006. Zircon isotope evidence for ≥3.5Ga continental crust in the Yangtze craton of China. Precambrian Research, 146(1-2): 16-34

Zheng JP, Griffin WL, O’Reilly SY, Zhang M, Pearson N and Pan YM. 2006. Widespread Archean basement beneath the Yangtze craton. Geology, 34(6): 417-420

Zheng YF, Fu B, Gong B and Li L. 2003. Stable isotope geochemistry of ultrahigh pressure metamorphic rocks from the Dabie-Sulu orogen in China: Implications for geodynamics and fluid regime. Earth-Science Reviews, 62(1-2): 105-161

Zheng YF, Zhou JB, Wu YB and Xie Z. 2005. Low-grade metamorphic rocks in the Dabie-Sulu orogenic belt: A passive-margin accretionary wedge deformed during continent subduction. International Geology Review, 47(8): 851-871

Zheng YF and Zhang SB. 2007. Formation and evolution of Precambrian continental crust of southern China. Chinese Science Bulletin, 52(1): 1-10

Zhao ZF, Zheng YF, Wei CS, Wu YB, Chen FK and Jahn BM. 2005. Zircon U-Pb age, element and C-O isotope geochemistry of post-collisional mafic-ultramafic rocks from the Dabie orogen in east-central China. Lithos, 83(1-2): 1-28

Zhao ZF, Zheng YF, Wei CS and Wu YB. 2007. Post-collisional granitoids from the Dabie orogen in China: Zircon U-Pb age, element and O isotope evidence for recycling of subducted continental crust. Lithos, 93(3-4): 248-272

Zhao ZF, Zheng YF, Wei CS, Chen FK, Liu XM and Wu FY. 2008. Zircon U-Pb ages, Hf and O isotopes constrain the crustal architecture of the ultrahigh-pressure Dabie orogen in China. Chemical Geology, 253(3-4): 222-242

Zhao ZF and Zheng YF. 2009. Remelting of subducted continental lithosphere: Petrogenesis of Mesozoic magmatic rocks in the Dabie-Sulu orogenic belt. Science in China (Series D), 52(9): 1295-1318

Zhao ZF, Zheng YF, Wei CS and Wu FY. 2011. Origin of postcollisional magmatic rocks in the Dabie orogen: Implications for crust-mantle interaction and crustal architecture. Lithos, 126(1-2): 99-114

附中文參考文獻(xiàn)

侯可軍, 李延河, 鄒天人, 曲曉明, 石玉若, 謝桂青. 2007. LA-MC-ICP-MS鋯石Hf同位素的分析方法及地質(zhì)應(yīng)用. 巖石學(xué)報(bào), 23(10): 2595-2604

黃凡, 王登紅, 陸三明, 陳毓川, 王波華, 李超. 2011. 安徽省金寨縣沙坪溝鉬礦輝鉬礦Re-Os年齡——兼論東秦嶺-大別山中生代鉬成礦作用期次劃分. 礦床地質(zhì), 30(6): 1039-1057

李法嶺. 2011. 河南大別山北麓千鵝沖特大隱伏斑巖型鉬礦床地質(zhì)特征及成礦時(shí)代. 礦床地質(zhì), 30(3): 457-468

李厚民, 葉會(huì)壽, 王登紅, 陳毓川, 屈文俊, 杜安道. 2009. 豫西熊耳山寨凹鉬礦床輝鉬礦錸-鋨年齡及其地質(zhì)意義. 礦床地質(zhì), 28(2): 133-142

李毅, 李諾, 楊永飛, 王玭, 糜梅, 張靜, 陳紅瑾, 陳衍景. 2013. 大別山北麓鉬礦床地質(zhì)特征和地球動(dòng)力學(xué)背景. 巖石學(xué)報(bào), 29(1): 95-106

李永峰, 毛景文, 胡華斌, 郭保健, 白鳳軍. 2005. 東秦嶺鉬礦類(lèi)型、特征、成礦時(shí)代及其地球動(dòng)力學(xué)背景. 礦床地質(zhì), 22(3): 292-304

劉福來(lái), 薛懷民. 2007. 蘇魯-大別超高壓巖石中鋯石SHRIMP U-Pb定年研究——綜述和最新進(jìn)展. 巖石學(xué)報(bào). 23(11): 2737-2756

毛景文, 謝桂青, 張作衡, 李曉峰, 王義天, 張長(zhǎng)青, 李永峰. 2005. 中國(guó)北方中生代大規(guī)模成礦作用的期次及其地球動(dòng)力學(xué)背景. 巖石學(xué)報(bào), 21(1): 169-188

孫景貴, 張勇, 邢樹(shù)文, 趙克強(qiáng), 張?jiān)鼋? 白令安, 馬玉波, 劉勇勝. 2012. 興蒙造山帶東緣內(nèi)生鉬礦床的成因類(lèi)型、成礦年代及成礦動(dòng)力學(xué)背景. 巖石學(xué)報(bào), 28(4): 1317-1332

王強(qiáng), 趙振華, 熊小林. 2000. 桐柏-大別造山帶燕山晚期A(yíng)型花崗巖的厘定. 巖石礦物學(xué)雜志, 19(4): 297-306

魏慶國(guó), 姚軍明, 趙太平, 孫亞莉, 李晶, 原振雷, 喬波. 2009. 東秦嶺發(fā)現(xiàn)～1.9Ga鉬礦床——河南龍門(mén)店鉬礦床Re-Os定年. 巖石學(xué)報(bào), 25(11): 2747-2751

向必偉. 2009. 北大別造山后伸展過(guò)程構(gòu)造熱年代學(xué)與變形模擬研究. 博士學(xué)位論文. 合肥: 合肥工業(yè)大學(xué), 1-117

謝智, 鄭永飛, 閆峻, 錢(qián)卉. 2004. 大別山沙村中生代A型花崗巖和基性巖的源區(qū)演化關(guān)系.巖石學(xué)報(bào), 20(5): 1175-1184

辛洪波, 曲曉明. 2008. 西藏岡底斯斑巖銅礦帶含礦巖體的相對(duì)氧化狀態(tài): 來(lái)自鋯石Ce(IV)/Ce(III)比值的約束. 礦物學(xué)報(bào), 28(2): 152-160

楊梅珍, 曾鍵年, 覃永軍, 李法嶺, 萬(wàn)守全. 2010. 大別山北緣千鵝沖斑巖型鉬礦床鋯石U-Pb和輝鉬礦Re-Os年代學(xué)及其地質(zhì)意義. 地質(zhì)科技情報(bào), 29(5): 35-45

葉會(huì)壽, 毛景文, 李永峰, 郭保健, 張長(zhǎng)青, 劉珺, 閆全人, 劉國(guó)印. 2006. 東秦嶺東溝超大型斑巖型鉬礦SHRIMP鋯石U-Pb和輝鉬礦Re-Os年齡及其地質(zhì)意義. 地質(zhì)學(xué)報(bào), 80(7): 1078-1088

袁順達(dá), 侯可軍, 劉敏. 2010. 安徽寧蕪地區(qū)鐵氧化物-磷灰石礦床中金云母Ar-Ar定年及其地球動(dòng)力學(xué)意義. 巖石學(xué)報(bào), 26(3): 797-808

翟明國(guó). 2010. 華北克拉通的形成演化與成礦作用. 礦床地質(zhì), 29(1): 24-36

張國(guó)偉, 張本仁, 袁學(xué)誠(chéng), 肖慶輝. 2001. 秦嶺造山帶與大陸動(dòng)力學(xué). 北京: 科學(xué)出版社, 1-729