| 翁望飞.皖南燕山期高钾钙碱性埃达克岩厘定及岩石成因[J].地质与勘探,2011,47(6):967-981 |
| 皖南燕山期高钾钙碱性埃达克岩厘定及岩石成因 |
| Geochemical Characteristics and Petrogenesis of High-K Calc-alkaline Adakite ofthe Yanshanian Epoch in South Anhu |
| 投稿时间：2011-02-26 修订日期：2011-08-09 |
| DOI： |
| 中文关键词: 埃达克岩 地球化学特征 构造环境 岩石成因 燕山期 皖南 |
| 英文关键词: Adakite,geochemical characteristic,structural environment,petrogenesis,Yanshanian,south Anhui |
| 基金项目:安徽省国土资源厅公益性地质调查基金项目《闪里幅(H50E013014)1 颐5 万区域地质矿产调查》(项目编号:2010-g-11)资助 |
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| 中文摘要: |
| [摘 要]皖南及邻区晚侏罗世-早白垩世早期中酸性岩浆岩产于扬子陆块江南古隆起东段,主要岩石类型为花岗闪长岩,主矿物组合为斜长石+石英+钾长石+角闪石依黑云母,副矿物有磷灰石、锆石、榍石、磁铁矿、钛铁矿等。岩石主量元素具有高SiO2(66.81%)、Al2O3(15.23%)、K2O/ Na2O(1.01),低TiO2(0.49%)、MgO(1.49%)、CaO(3.18%)、P2O5(0.18%) 等特征;A/ CNK 值为1.04,呈弱过铝态,里特曼指数滓平均2.07,指示其属钙碱性系列。稀土元素表现为LREE 富集,HREE 亏损,具低Y(13.99×10-6)和Yb(1.4×10-6);微量元素表现为富集LILE(Rb、La、Ba、Sr) 和亏损HFSE(Nb、Ta、Zr、Y),具高Sr(494.8×10-6)的特征,较高Sr/ Y(39.05) 和La/ Yb(24.34) 比值,具弱的Eu(0.8) 异常,ISr平均为0.7092,εNd<0。岩石学及地球化学特征分析认为皖南晚侏罗世-早白垩世早期花岗闪长岩为“C冶型、高钾钙碱性埃达克岩,其发育于构造应力由挤压转变为伸展的转折期,埃达克岩浆源自印支期加厚地壳受地幔热物质上涌影响而形成的部分熔融物。 |
| 英文摘要: |
| Abstract:The acidic magmatic rocks of late Jurassic-early Cretaceous in South Anhui are indigenous to the eastern part of Jiangnan paleouplift in the
Yangtze landmass,of which the primary rock type is calc-alkaline granodiorite with the major mineral assemblage being plagioclase + quartz + potassium feldspar + amphibole±biotit and some accessory minerals being apatite,zircon,titanite,magnetite,and ilmenite. The magmatic rocks belong to calc-alkaline series with geochemical characteristics of higher SiO2(66.81%),Al2O3(15.23%),K2O/ Na2O (1.01) and lower TiO2(0.49%),MgO (1.49%),CaO (3.18%),and P2O5(0.18%). They are also obviously rich in LREE and LILE(Rb,La,Ba,Sr),and depleted in HREE and HSFE(Nb,Ta,Zr,Y) with slightly negative δEu(0.8),higher Sr/ Y(39.05) and La/ Yb(24.34),lower Y(13.99×10-6) and Yb(1.4×10-6),and meanwhile ISr≈0.7092,εNd<0. The analysis of petrological and geochemical characteristics suggests that the magmatic rocks of late Jurassic-early Cretaceous in South Anhui are "C"type,high-K calc-alkaline adakite(HKCAA),which were formed from partial melting of the thickened lower crust by delamination in Mesozoic in eastern China. |
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