| 扬子陆块西南缘早前寒武纪撮科杂岩记录的多期岩浆-变质事件 |
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| 引用本文： | 崔晓庄,任光明,孙志明,王鹏,刘石磊,邓奇,任飞,庞维华. 扬子陆块西南缘早前寒武纪撮科杂岩记录的多期岩浆-变质事件[J]. 地球科学, 2020, 45(8): 3054-3069. DOI: 10.3799/dqkx.2020.199 |
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| 作者姓名： | 崔晓庄 任光明 孙志明 王鹏 刘石磊 邓奇 任飞 庞维华 |
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| 作者单位： | 中国地质调查局成都地质调查中心, 四川成都 610081 |
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| 基金项目： | 国家自然科学基金项目41872120国家自然科学基金项目41772115国家自然科学基金项目41802137中国地质调查局项目DD20190054中国地质调查局项目DD20190375 |
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| 摘 要： | 撮科杂岩是最近在滇中地区发现的早前寒武纪基底杂岩，对深入探究扬子陆块早期演化具有重要意义.报道了4件代表性岩石样品的锆石U-Pb年代学和Hf同位素新数据.奥长花岗质片麻岩样品的结晶年龄为2 845±33 Ma，具有正的锆石εHf（t）值（1.7~4.6）和相对年轻的亏损地幔二阶段（TDM2）模式年龄（2.97~3.12 Ga），表明其形成于新生地壳的重熔.变二长花岗岩和片麻状花岗岩样品的结晶年龄分别为2 401±15 Ma和2 320±16 Ma，显示负的锆石εHf（t）值（-6.2~-0.8）和明显老的TDM2模式年龄（2.90~3.11 Ga），指示其来自古老地壳物质的重熔.斜长黑云碎粒岩的变质锆石的年龄为1 948±16 Ma，结合已有变质年龄揭示一期1.96~1.95 Ga区域变质作用.扬子陆块西南缘存在太古代结晶基底，并保留了与Nuna超大陆聚合有关的多期构造-岩浆事件的记录.
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| 关 键 词： | 太古代 古元古代 岩浆-变质事件 撮科杂岩 扬子陆块 地质年代学 |
| 收稿时间： | 2020-06-09 |
Multiple Tectonothermal Events Recorded in the Early Precambrian Cuoke Complex in the Southwestern Yangtze Block,South China |
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| Abstract: | The Cuoke Complex, a newly identified Early Precambrian basement complex in central Yunnan, bears key information for the early evolution of the Yangtze Block. Here, we present zircon U-Pb geochronological and Hf isotopic data of four representative samples collected from this complex. Magmatic zircons of one trondjemitic gneiss sample yield a crystallization age of 2 845±33 Ma, with positive εHf(t) values of 1.7-4.6 and relatively young depleted mantle two stage (TDM2) model ages of 2.97-3.12 Ga, suggestive of the derivation from remelting of juvenile crust. Meta-monzogranite and gneissic granite yield ages of 2 401±15 Ma and 2 320±16 Ma respectively. They show negative zircon εHf(t) values of -6.2 to -0.8 and older TDM2 model ages of 2.90-3.11 Ga, indicating that they were formed by remelting of ancient crustal materials. Metamorphic-origin zircons of one plagioclase-biotite cataclasite sample give an age of 1 948±16 Ma. Together with available metamorphic age data, it is revealed that one episode of regional metamorphism occurred at 1.96-1.95 Ga. Our new dataset confirms the existence of Archean basement rocks in the Cuoke Complex. Moreover, multiple magmatic and metamorphic events related to the assembly of the Nuna supercontinent extensively took place in the southwestern Yangtze Block, South China. |
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