Archaean to Palaeoproterozoic crustal evolution of the Aravalli mountain range, NW India, and its hinterland: The U–Pb and Hf isotope record of detrital zircon
Archaean to Palaeoproterozoic crustal evolution of the Aravalli mountain range, NW India, and its hinterland: The U–Pb and Hf isotope record of detrital zircon
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DOI：
10.1016/j.precamres.2011.03.005
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发表时间：
2011-05
影响因子：
3.8
通讯作者：
Parampreet Kaur;A. Zeh;N. Chaudhri;A. Gerdes;M. Okrusch
中科院分区：
文献类型：
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作者：
Parampreet Kaur;A. Zeh;N. Chaudhri;A. Gerdes;M. Okrusch
Aravalli山脉北德里褶皱带最古老的Alwar石英岩碎屑锆石的原位U-Pb-Hf同位素分析表明，印度西北部基底具有共同的太古代-古元古代演化历史，是3.70 ~ 1.71 Ga期间几次地壳形成和地壳改造事件的结果。锆石年龄谱表明，大部分年龄在1.87- 1.71Ga（75%），小的年龄峰在2.5- 2.2Ga和2.9- 2.7Ga，古太古代年龄为3.27- 3.23Ga。Lu-Hf同位素数据表明，阿拉瓦利山脉及其腹地最古老的地壳形成于约3.7Ga的亏损地幔源区。此外，数据还表明，阿尔瓦沉积物的腹地在3.25、2.89、2.67、2.51和1.87-1.80 Ga受到几个新“幼年”地壳形成时期的影响，而地壳改造在2.62-2.45、2.2和1.87-1.77 Ga占主导地位。具有捕虏晶核和变质增生的锆石，还表明源区受到高品位（？）根据我们的新数据，结合现场关系和印度西北部的西印度基底中现有的锆石年龄，可以得出结论，Alwar石英岩中的古-新太古代碎屑（3.3-2.5 Ga）来自近源。主要的晚古元古代锆石碎屑（1.87-1.71 Ga）来自附近的基底，这是受俯冲-增生构造在1.85 Ga左右，并在1.77 Ga的第一个，也许是后碰撞裂谷相关的阶段。后一个事件是迄今为止尚未认识的，并早于第二阶段的裂谷相关的A型岩浆活动在1.72-1.70 Ga。最年轻的碎屑锆石年龄。1.71 Ga表明，在北德里褶皱带的沉积和变质作用晚于裂谷相关的A型岩浆活动的第二阶段。
In situ U–Pb–Hf isotope analyses of detrital zircons from the Alwar quartzite, the oldest member of the North Delhi fold belt in the Aravalli mountain range, indicate that the basement of NW India shares a common Archaean-Palaeoproterozoic evolutionary history, and is a consequence of several crust-forming and crust-reworking events between 3.70 and 1.71 Ga. This is suggested by a zircon age spectrum with most ages at 1.87-1.71 Ga (75%), minor age peaks at 2.5-2.2 and 2.9-2.7 Ga, and Palaeoarchaean ages of 3.27-3.23 Ga. Lu–Hf isotope data reveal that the oldest crust, either in the Aravalli mountain range or in its hinterland, was formed from a depleted mantle source at around 3.7 Ga. Furthermore, the data also indicate that the hinterland of the Alwar sediments was affected by several periods of new “juvenile” crust formation at 3.25, 2.89, 2.67, 2.51, and 1.87-1.80 Ga, while crustal reworking was predominant at 2.62-2.45, 2.2 and 1.87-1.77 Ga. Zircons with xenocrystic cores and metamorphic overgrowths, additionally suggest that the source region was affected by high-grade (?) metamorphic events at 2.5 and 2.2 Ga.Based on our new data, in conjunction with field relationships and existing zircon ages in the Archaean basement of NW India, it can be concluded that the Palaeo- to Neoarchaean detritus (3.3-2.5 Ga) in the Alwar quartzite stems from proximal sources. The predominant late Palaeoproterozoic zircon detritus (1.87-1.71 Ga) was supplied from a nearby basement, which was affected by subduction-accretion tectonics at around 1.85 Ga, and by a first, perhaps post-collisional rift-related phase at 1.77 Ga. The latter event is unrecognized so far, and predates a second phase of rift-related A-type magmatism at 1.72-1.70 Ga. The youngest detrital zircon age of ca. 1.71 Ga suggests that the sedimentation and metamorphism in the North Delhi fold belt postdate the second phase of rift-related A-type magmatic activity.