| 格咱岛弧带热林二长花岗岩的岩石成因及动力学背景:岩石地球化学、年代学及Hf同位素约束 |
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| 引用本文： | 杨富成.格咱岛弧带热林二长花岗岩的岩石成因及动力学背景:岩石地球化学、年代学及Hf同位素约束[J].地质与勘探,2017,53(2):283-289. |
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| 作者姓名： | 杨富成 |
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| 作者单位： | 昆明理工大学国土资源工程学院，云南昆明； 中国地质调查局成都地质调查中心，四川成都 |
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| 基金项目： | 云南科技领军人才计划项目（编号:2013HA001），国家自然科学基金项目（编号:41502076），云南省教育厅科学研究基金（编号:2015Y066）和昆明理工大学省人培训项目（编号:KKSY201421042）联合资助。 |
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| 摘 要： | 云南格咱岛弧带是近年来西南三江特提斯构造带新发现的重要Cu-Mo多金属成矿带之一,燕山晚期伴随着碰撞型岩浆侵入作用形成了斑岩-矽卡岩型Mo(Cu)和热液型W(Mo)矿床。其中,热林Mo-Cu矿床是区内燕山晚期成岩成矿作用的代表性矿床。本文对热林Mo-Cu矿床二长花岗岩进行了锆石LA-ICP-MS U-Pb定年、岩石地球化学和Lu-Hf同位素分析。结果表明,热林二长花岗岩属高硅(SiO_2=69.88%~74.58%)、富碱(K_2O+Na_2O=7.24%~8.62%)的高钾钙碱性、准铝质(A/CNK=0.93~1.05)花岗岩。岩石具有较高的稀土元素总量(∑REE为(80.72~284.85)×10-6,平均值为190.86×10-6),轻重稀土元素分馏程度较高,具Eu负异常(δEu=0.46~0.83),相对富集LREE和LILE(K、Rb),亏损HFSE(Nb、Ta、P、Ti)和HREE,具埃达克岩亲和性。本文两件二长花岗岩样品的锆石U-Pb年龄分别为79.4±2.0 Ma(MSWD=1.1)、78±1.6 Ma(MSWD=1.8),代表了热林Mo-Cu矿床二长花岗岩的岩浆侵位结晶时代为燕山晚期;锆石的εHf(t)值为-12.12~-4.41,均小于0,二阶段模式年龄峰值在1.35~1.4Ga之间,揭示了热林二长花岗岩来源于中元古代地壳基底的深熔作用。研究表明,热林二长花岗岩是碰撞后的陆内伸展环境下壳源岩浆侵位结晶的产物,并伴随有成矿热液活动形成了Mo-Cu多金属矿化,最终形成热林Mo-Cu多金属矿床,其成岩成矿作用与燕山期碰撞造山作用密切相关。
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| 关 键 词： | 二长花岗岩 动力学背景 燕山晚期 热林 格咱岛弧带 |
| 收稿时间： | 2016/12/23 0:00:00 |
| 修稿时间： | 2017/1/16 0:00:00 |
Rock genesis and dynamic background of the Relin monzogranite in the Geza arc belt, Yunnan: Constrains from petrochemistry, chronology, and Hf isotope |
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| Yang Fu-cheng.Rock genesis and dynamic background of the Relin monzogranite in the Geza arc belt, Yunnan: Constrains from petrochemistry, chronology, and Hf isotope[J].Geology and Prospecting,2017,53(2):283-289. |
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| Authors: | Yang Fu-cheng |
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| Institution: | Kunming University of Science and Technology, Kunming, Yunnan; Chengdu Geological Survey Center of China Geological Survey, Chengdu, Sichuan |
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| Abstract: | The Geza arc belt is one of the newly discovered important Cu-polymetallic metallogenic belts in the southwestern Sanjiang Tethyan tectonic zone.With collision-type magmatic intrusion activity,porphyry-skarn Mo (Cu) and hydrothermal W (Mo) deposits were formed during the late Yanshanian period in this region.Among them,the Relin Mo-Cu deposit is representative of the diagenesis and mineralization.This paper presents the analyses of petrochemistry,zircon LA-ICP-MS U-Pb dating and Lu-Hf isotope in this typical deposit.The results show that Relin monzogranite is rich in SiO2 (69.88％ ～ 74.58％) and K2O + Na2O(7.24％ ～ 8.62％),which belongs to high-K calc-alkali and quasi-aluminous granite(A/CNK =0.93～1.05,less than 1.1).The rock has high ΣREE (ΣREE are 80.72×10-s ～284.85×10-6,190.86×10-6 on average) and negative Eu anomaly (δEu =0.46 ～ 0.83),and high fractionation degree of LREE and HREE.It is also enriched in LREE and LILE (K,Rb) and depleted in HFSE (Nb,Ta,P,Ti)and HREE,implying a characteristic of adakite affinity.The zircon U-Pb ages of two samples are 79.4 ±2Ma (MSWD =1.1) and 78 ± 1.6Ma (MSWD =1.8),respectively,which represent the crystallization age of monzogranite magma as late Yanshanian.The value of εHf(t) from two simples range from-12.12 to-4.41 (less than zero),and the peak value of tDM2 age is between 1.35 ～ 1.4Ga,which reveals that the Relin monzongranite originated from the deep melting of the Mesoproterozoic crustal basement.The research shows that the Relin monzongranite is the product of crustal magma emplacement in an intracontinental extensional environment after the collision in late Yanshanian,and developed Mo-Cu polymetallic mineralization with ore-forming hydrothermal solution,which finally formed Mo-Cu polymetallic deposit.Thus the diagenesis and mineralization in the Relin Mo -Cu deposit was closely related to the collisional orogeny. |
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| Keywords: | monzogranite dynamic background late Yanshanian period Relin Geza arc belt |
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