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| 西藏拉萨地块西部扎布耶茶卡火山岩的成因与意义 | |
| 引用本文： | 赵志丹,莫宣学,朱弟成,Yaoling Niu,董国臣,周 肃,廖忠礼,Don J. DePaolo.西藏拉萨地块西部扎布耶茶卡火山岩的成因与意义[J].地质通报,2009,28(12):1730-1740. |
| 作者姓名： | 赵志丹 莫宣学 朱弟成 Yaoling Niu 董国臣 周 肃 廖忠礼 Don J. DePaolo |
| 作者单位： | 1. 地质过程与矿产资源国家重点实验室/中国地质大学地球科学与资源学院,北京,100083 2. 地质过程与矿产资源国家重点实验室/中国地质大学地球科学与资源学院,北京,100083;中国地质调查局成都地质矿产研究所,四川,成都,610082 3. 中国地质调查局成都地质矿产研究所,四川,成都,610082 4. 伯克利加里福尼亚大学地球科学系,伯克利 CA 94720,美国 |
| 基金项目： | 国家重点基础研究发展规划项目，国家自然科学基金项目，中国地词局综合研究项目和高等学校学科创新引智计划111项目 |
| 摘 要： | 近年来在青藏高原南部拉萨地块不断发现的碰撞后钾质和超钾质岩石，对于揭示印度与亚洲大陆碰撞以来高原岩石圈的深部作用与过程发挥了重要作用。分布在拉萨地块西部扎布耶茶卡东岸的钾质和超钾质火山岩主体喷发时代为中新世（约16Ma），出露面积约为400km2，火山岩持续喷发0.45Ma，估算的喷发速率约为0.26×10-3km3/a。岩石包括3种类型，第一类（约16Ma）为超钾质的粗面安山岩，SiO2低（55%~58 %），高Fe2O3、MgO、TiO2；第二类（约27Ma）为钾玄质的响岩和粗面岩；第三类是高SiO2的钾玄质—超钾质粗面岩（SiO2＝59%~64％）和流纹岩（SiO2＝69％）。岩石显示轻稀土元素、大离子亲石元素高度富集和部分高场强元素亏损的特征，部分中酸性岩石显示高Sr低Y的埃达克岩的属性。岩石的Sr-Nd-Pb-O同位素组成与拉萨地块典型的超钾质岩石明显不同，显示亲青藏高原北部地球化学省的地球化学特征。扎布耶茶卡不同类型的岩浆代表了碰撞后高原南部岩石圈减薄作用导致的岩石圈不同层次的岩石部分熔融的产物。 |
| 关 键 词： | 碰撞后 超钾质岩石 地球化学 扎布耶茶卡 青藏高原 |
Petrogenesis and implications of the volcanic rocks in Zabuye salt lake area, western Lhasa terrane, Tibet, China. |
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| ZHAO Zhi-dan,MO Xuan-xue,ZHU Di-Cheng,NIU Yao-ling,DONG Guo-chen,ZHOU Su,LIAO Zhong-li,DEPAOLO Don J..Petrogenesis and implications of the volcanic rocks in Zabuye salt lake area, western Lhasa terrane, Tibet, China.[J].Geologcal Bulletin OF China,2009,28(12):1730-1740. | |
| Authors: | ZHAO Zhi-dan MO Xuan-xue ZHU Di-Cheng NIU Yao-ling DONG Guo-chen ZHOU Su LIAO Zhong-li DEPAOLO Don J |
| Abstract: | The postcollisional potassic and ultrapotassic rocks have been found recently in southern Tibetan plateau, which are important clues in studying the deep processes since India collided with Asia. The volcanic rocks located in the east bank of Zabuye salt lake in western Lhasa terrane were dated to be ～16 Ma, with an area of ～ 400 km~2. The volcano erupted in ～0.45 Ma with an eruption rate of 0.26×10~(-3)km~3/year. Three types of rock were found in the Zabuye volcanics. Type one (～16 Ma) are ultrapotassic trachyan-desite, with lower SiO_2 (55%-58%), high Fe_2O_3, MgO, and TiO_2. Type two (～27 Ma) are shoshonitic phonolite and trachyte. Typethree are shoshonitic and ultrapotassic trachyte (SiO_2=59%-64%) and rhyolites (SiO_2=69%), with high Sr lower Y adakite-affinity. The rocks, as a whole, show enrichment of light rare earth elements (REEs) and large ion lithosphile elements (LILE), and are low in some high field strength elements (HFSEs). The Sr-Nd-Pb-O isotopic composition of the Zabuye rocks differed from the typical ultrapotassic rocks in southern Tibet. Instead, they show similar nature to the rocks from the northern Tibet geochemical province. The Zabuye rocks imply that, they originated from partial melting of different depth of the lithospheric mantle and thickened lower crust that caused by the thinning process in southern Tibet. |
| Keywords: | postcollision ultrapotassic rocks geochemistry Zabuye salt lake Qinghai-Tibet Plateau |
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