| 摘要: |
| 根据K-Ar同位素年代学研究成果,将赤布张错新生代火山活动划分为3期:第Ⅰ期(40.1~35.1Ma)火山喷发较弱,形成小范围分布的细粒安粗岩和斑状粗面岩;第Ⅱ期(26.5~17.6Ma)火山喷溢最为强烈,形成大面积厚层黑色气孔状安粗岩;第Ⅲ期(5.5~4.61Ma)由潜火山作用形成球粒状、斑状粗面岩岩丘。新生代火山岩系包括高钾钙碱性系列和钾玄岩系列,高钾钙碱性火山岩形成于始新世,属于壳源岩浆系列;钾玄岩系火山岩形成于中新世-上新世,属于幔源岩浆系列。由老到新,岩石系列由高钾钙碱性系列→钾玄岩系列演化,岩性由安粗岩→粗面岩演化。 |
| 关键词: 新生代 火山岩 赤布张错 羌塘 |
| DOI： |
| 附件 |
| 投稿时间：2004-03-23 |
| 基金项目:国土资源大调查项目“1∶25万《赤布张错幅》区域地质调查”(20013900018)。 |
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| The Cenozoic volcanic rocks from the Chibuzhang Lake area in the Qiangtang area |
| WEI Jun-qi, WANG Jian-xiong, NIU Zhi-jun |
| (Yichang Institute of Geology and Mineral Resources, Yichang 443003, Hubei, China) |
| Abstract: |
| Three stages have been recognized for the volcanic activity in the Chibuzhang lake area in northern Xizang on the basis of the K-Ar isotopic age determinations:(1) Stage Ⅰ (40.1-35.1 Ma),during which the volcanic eruption was relatively weak,and only small-scale of fine-grained latite and porphyritic trachyte were formed;(2) Stage Ⅱ (26.5-17.6 Ma),during which the volcanic eruption reached its peak,resulting in the formation of widespread thick-bedded balck vesiculate latite,and Stage Ⅲ (5.5-4.61 Ma),during which the crypto-volcanism permitted the pelletoidal and porphyritic trachyte domes. The Cenozoic volcanic rock series consist of high-potassium calc-alkaline series and shonshonite series. The former ones may be traced back to the Eocene and originated from the crust-derived magmas,whereas the latter ones are of Miocene and Pliocene age,and resulted from the mantle-derived magmas. The rock series record the evolution from the high-potassium calc-alkaline series to shonshonite series,while the lithologies show the evolution from latite to trachyte. |
| Key words: Cenozoic volcanic rocks Chibuzhang Lake Qiangtang |
