| 罗 改,汤 晶,肖 禹,贾小川,杨学俊,肖 典.滇西北龙蟠地区中三叠世辉绿岩锆石 U-Pb定年及地质意义[J].甘肃地质,2026,35(1):17-26 |
| 滇西北龙蟠地区中三叠世辉绿岩锆石 U-Pb定年及地质意义 |
| ZIRCON U-Pb DATING AND GEOLOGICAL SIGNIFICANCE OF THE MIDDLE TRIASSIC DIABASE IN LONGPAN AREA OF NORTHWEST YUNNAN, CHINA |
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| DOI：10.27027/j.cnki.ISSN2097-6704.2026.01.002 |
| 中文关键词: 辉绿岩 锆石U-Pb定年 中三叠世 地质意义 龙蟠地区 |
| 英文关键词:diabase zircon U-Pb dating Middle Triassic geological significance Longpan area |
| 基金项目:中国地质调查局项目（DD20160345-01）资助 |
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| 中文摘要: |
| 青藏高原东南缘滇西北龙蟠地区新识别出一套三叠纪辉绿岩，采用LA-ICP-MS方法进行锆石U-Pb年代学分析，获得其206Pb ／238U加权平均年龄为（243. 9 ± 2. 2）Ma（MSWD = 3. 0，n = 14），形成于中三叠世。 地球化学特征显示，岩石具有低硅（SiO2 = 49. 01% ~ 53. 66%）、高Mg#值特征（51. 6 ~ 63. 5），富集Rb、Th、U等大离子亲石元素，亏损Nb、Zr、Hf等高场强元素。 综合分析认为，辉绿岩起源于石榴石二辉橄榄岩的部分熔融，形成于甘孜—理塘洋壳向西俯冲增生作用过程中的弧后伸展构造环境。 |
| 英文摘要: |
| A new set of Triassic diabases are identified in Longpan area, southeast margin of Qinghai-Tibet Plateau. LA -ICP -MS Zircon U -Pb geochronological analysis shows that the 206Pb ／238U weighted mean age of the Triassic diabases is （243.9 ± 2.2） Ma （MSWD = 3.0, n = 14）, which are formed in the Middle Triassic. Geochemical characteristics show that, the rocks with low silicon （SiO2 = 49.01% ~ 53.66%） and high Mg# value （51. 6 ~ 63. 5）, are riched in LILE such as Rb, Th and U, and deficited in HFSE such as Nb, Zr and Hf. Comprehensive analysis shows that, the diabases originated from the partial melting of garnet dipyroperidotite, was formed in the backarc extensional tectonic environment during the westward subduction and accretion of the Garzi-Litang ocean crust. |
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