| 黄艳娜,黎敦朋,肖爱芳,徐松明.北秦岭造山带翠华山黑云母花岗岩LA-ICP-MS锆石U-Pb测年及地球化学特征[J].地质找矿论丛,2023,38(2):197-208 |
| 北秦岭造山带翠华山黑云母花岗岩LA-ICP-MS锆石U-Pb测年及地球化学特征 |
| Zircon LA-ICP-MS U-Pb dating and geochemical characteristics of Cuihuashan biotite granite in the North Qinling orogenic belt |
| 投稿时间：2022-08-15 |
| DOI：10.6053/j.issn.1001-1412.2023.02.009 |
| 中文关键词: 锆石U-Pb测年 晚侏罗世 部分熔融 翠华山 北秦岭地区 |
| 英文关键词:Zircon U-Pb dating Late Jurassic epoch patial melting Cuihuashan area the North Qinling mountain area |
| 基金项目:中国国家自然科学基金项目(编号:41872220)资助。 |
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| 中文摘要: |
| 秦岭翠华山水湫池地区分布的黑云母花岗岩是陕西翠华山国家山崩地质公园的崩塌母岩,目前还未见对其系统地开展年代学、地球化学研究。本文在野外调查的基础上,对翠华山水湫池地区分布的黑云母花岗岩首次进行了LA-ICP-MS锆石U-Pb测年、Lu-Hf同位素及全岩地球化学分析,获得锆石U-Pb加权平均年龄为149.4 Ma±1.1 Ma,时代属于晚侏罗世;结合前人的研究成果资料,翠华山复式岩体可能存在~227 Ma、~150 Ma、~119 Ma三期岩浆侵位活动;全岩地球化学分析具有高硅(w(SiO2)=69.83%~75.31%)、富钾(w(K2O)=2.71%~5.23%)、弱过铝质(A/CNK=1.00~1.07)特征,属于高钾钙碱性-钾玄岩Ⅰ型花岗岩;其轻、重稀土分馏明显(w(LREE)/w(HREE)=10.09~67.50),富集LILE(K、La、Pb、Sr)、亏损HFSE(Ta、Nb、P、Ti),Eu呈弱负异常—轻微正异常,且显示高Sr低Y花岗岩特征;锆石Hf同位素分析得出εHf(t)=-4.6~-1.4,T2DM(crust)=1.3 Ga~1.5 Ga,指示其可能为中元古代加厚下地壳物质部分熔融形成。 |
| 英文摘要: |
| Biotite granite is the parent rock of collapse rock in Cuihuashan National geo-park in Shuiqiuchi area, Qinling mountain. This paper deals with chronology and geochemistry of the granite. It is investigated in field and the zircon LA-ICP-MS U-Pb dating, Lu-Hf isotropic and bulk rock analysis are carried out for the first time. The weighted average age is 149.4±1.1 Ma corresponding to Jurassic Epoch. According to the previous data the granite is a complex intrusive body in which 3 emplacement took place at ~227 Ma, ~150 Ma and ~119 Ma respectively. Bulk rock analysis is characterized by high content of silica (w(SiO2)=69.83%-75.31%), enrichment of potassium (w(K2O)=2.71%-5.23%) and weak para-a luminous (A/CNK=100-107) belonging to high K calc-alkaline I type granite and by evident fraction of LREE and HREE (w(LREE)/w(HREE)=10.09-67.50), LILE (K, La, Pb, Sr) enrichment, HERE (Ta, Nb, P, Ti) depletion, weak negative-slight positive Eu anomaly, high Sr and low Y. Zircon Hf isotropic analysis εHf(t)=-4.6~-1.4, T2DM(crust)=1.3-1.5 Ga, indicates that the granite is possibly formed by partial melting materials of thickening crust during Middle Properozoic period. |
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