| 辽东中生代晚期和古近纪玄武岩及深源捕虏晶对岩石圈地幔性质的制约 |
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| 引用本文： | 王微,许文良,纪伟强,杨德彬,裴福萍.辽东中生代晚期和古近纪玄武岩及深源捕虏晶对岩石圈地幔性质的制约[J].高校地质学报,2006,12(1):30-40. |
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| 作者姓名： | 王微 许文良 纪伟强 杨德彬 裴福萍 |
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| 作者单位： | 吉林大学地球科学学院,长春 130026 |
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| 基金项目： | 教育部高校博士学科点基金(20040183065)，国家自然科学基金(40133020)，吉林大学创新基金 |
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| 摘 要： | 辽东地区玄武岩的K-Ar定年结果表明，曲家屯玄武岩形成于晚白垩世，K-Ar年龄为81．58±2．46Ma；乱石山子玄武岩形成于古近纪，K-Ar年龄为58．36±1．64Ma。本区玄武岩含有丰富的橄榄石、单斜辉石和角闪石捕虏晶。乱石山子玄武岩中橄榄石捕虏晶的Mg^#值（79．5-88．5之间，平均值为84）较曲家屯玄武岩中橄榄石捕虏晶Mg^#值（77．0～79．8之间，平均值为78．4）偏高；单斜辉石捕虏晶为透辉石，其从核部到边部的Mg^#等变化趋势与橄榄石类似；斜方辉石捕虏晶为占铜辉石，其Mg^#值介于85．2-87．6之间，平均值为86．4。捕虏晶发育的环状裂隙、扭折带、矿物成分环带以及捕虏晶与主岩Mg^#值之间的不平衡均暗示它们为玄武质岩浆上升捕获的早期岩浆晶出矿物的堆晶体。玄武岩的岩石地球化学分析结果表明：（1）它们属于碱性系列，为碱性玄武岩，曲家屯玄武岩较乱石山子玄武岩贫硅、镁，富钙、铝，它们均具有原始岩浆的特征；（2）二者具有相似的稀土元素配分模式，但曲家屯玄武岩轻稀土元素总量更高，且轻重稀土元素分离程度高；（3）二者具有相似的Sr-Nd同位素组成，Isr和εNd（t）值分别介于0．7039～0．7045和＋1．60～＋3．69，反映了亏损的岩石圈地幔特征。
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| 关 键 词： | 辽东 中生代晚期 古近纪 玄武岩 捕虏晶 岩石圈地幔 |
| 文章编号： | 1006-7493（2006）01-0030-11 |
| 收稿时间： | 2005-04-17 |
| 修稿时间： | 2005-06-10 |
Late Mesozoic and Paleogene Basalts and Deep-Derived Xenocrysts in Eastern Liaoning Province, China: Constraints on Nature of Lithospheric Mantle |
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| WANG Wei,XU Wen-liang,JI Wei-qiang,YANG De-bin,PEI Fu-ping.Late Mesozoic and Paleogene Basalts and Deep-Derived Xenocrysts in Eastern Liaoning Province, China: Constraints on Nature of Lithospheric Mantle[J].Geological Journal of China Universities,2006,12(1):30-40. |
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| Authors: | WANG Wei XU Wen-liang JI Wei-qiang YANG De-bin PEI Fu-ping |
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| Institution: | College of Earth Sciences, Jilin University, Changchun 130061, China |
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| Abstract: | The K-Ar dating results of basahs in eastern Liaoning Province indicate that Qujiatun and Luanshishanzi basahs were formed in the Late Cretaceous with an age of 81．58 4±2．46 Ma and in the Paleogene with an age of 58．36±1．64 Ma，respectively．Abundant deep-derived xenocrysts such as olivine，clinopyroxene，and hornblende have been found in the basalts．The olivine xenocrysts from Luanshishanzi basalt have higher Mg# values (79．5-88．5，ave．84)than those from Qujiatun basalt(77．0-79．8，ave．78．4)．The clinopyroxene in basalts is diopside，whose change trend in Mg# etc．from nuclear part to periphery is similar to that of olivine．The orthopyroxene in basalts is bronzite with the Mg# values of 85．2～87．6(ave．86．4)．The circle cracks，kink bands，compositionzoning，and equilibrium of Mg# values between olivine xenocrysts and host basahs imply that the xenocrysts could be the earlier magmatic cumulate caught by the host basaltic magmas．The petrological and geochemical data of the basalts show that(1)they are alkaline basalts，but the Qujiatun basalts are higher in CaO and A12O3，lower in SiO2 and MgO than the Luanshishanzi basalts (2)they have similar REE distribution patterns，but the Qujiatun basahs have higher REE abundances and LREE／HREE ratios than the Luanshishanzi basalts；(3)they have similar Sr-Nd isotopic compositions．The Isr and εNd(t)values are 0．7039～0．7045 and+1．60～+3．69，respectively．It implies that they could be derived from the depleted lithospheric mantle． |
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| Keywords: | eastern Liaoning Province Late Mesozoic Paleogene basalt xenocrysts lithospheric mantle |
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