UHT granulites of the Highland Complex, Sri Lanka II: Geochronological constraints and implications for Gondwana correlation
UHT granulites of the Highland Complex, Sri Lanka II: Geochronological constraints and implications for Gondwana correlation
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DOI：
10.2465/jmps.151230
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发表时间：
2016-07
影响因子：
0.7
通讯作者：
Y. Osanai;K. Sajeev;N. Nakano;Ippei Kitano;W. Kehelpannala;Ryosuke Kato;T. Adachi;S. Malaviarachchi
中科院分区：
文献类型：
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作者：
Y. Osanai;K. Sajeev;N. Nakano;Ippei Kitano;W. Kehelpannala;Ryosuke Kato;T. Adachi;S. Malaviarachchi
斯里兰卡高原杂岩的区域超高温（UHT）变质作用是公认的，并在我们的冈瓦纳超大陆的构造历史的理解具有重要作用。含镁铝麻粒岩的锆石U-Pb定年结果表明，变质年龄主要在620-590 Ma和563-525 Ma之间，没有发现更老的锆石核。具有Grt-Sil-Spl-Crd组合的泥质麻粒岩样品具有相似的变质年龄，具有类似于602，563和526 Ma的一致数据群，继承的锆石核年龄为2040至1600 Ma。泥质麻粒岩也经历了两期变质作用（565-520和622-580 Ma）。其中一些泥质麻粒岩样品继承了3060 - 760 Ma的锆石核。镁铁质麻粒岩中锆石的年龄范围为566-533和620 - 578 Ma。钙硅酸盐麻粒岩样品也有类似的年龄人口在591，541，和524马。结合这些新的结果与先前公布的年龄从斯里兰卡和以前相邻大陆片段冈瓦纳，我们建议，（拉诺察拉剪切带以南）、印度南部的北方、马杜赖南部和特里凡得琅地块、斯里兰卡高地复合体、和东南极Lutzow-Holm杂岩中的Skallen群代表了一个独特的变质带，区域上经历了Ediacaran-冈瓦纳超大陆合并过程中的寒武纪超高温事件。
The regional ultrahigh-temperature (UHT) metamorphism of the Highland Complex, Sri Lanka is well established and has an important role in our understanding of the tectonic history of the Gondwana supercontinent. U-Pb zircon dating of sapphirine-bearing Mg-Al granulites yielded two major metamorphic age populations at approximately 620-590 and 563-525 Ma with no evidence of older zircon cores. Pelitic granulite samples with a Grt-Sil-Spl-Crd assemblage have similar metamorphic ages with concordant data clusters at similar to 602, 563, and 526 Ma and inherited zircon cores aged from 2040 to 1600 Ma. The pelitic granulites also underwent two stages of metamorphism (565-520 and 622-580 Ma). Some of these pelitic granulite samples have inherited zircon cores ranging from 3060 to 760 Ma. Zircons in mafic granulite samples have age ranges of 566-533 and 620578 Ma. A calc-silicate granulite sample also has similar age populations at 591, 541, and 524 Ma. Combining these new results with previously published ages from Sri Lanka and formerly adjacent continental fragments of Gondwana, we propose that the terranes in southern Madagascar (south of Ranotsara Shear Zone), Northern and Southern Madurai and the Trivandrum Blocks of southern India, the Highland Complex of Sri Lanka, and the Skallen Group in the Lutzow-Holm Complex of East Antarctica represent a unique metamorphic belt that regionally experienced the Ediacaran-Cambrian UHT event during the amalgamation of the Gondwana super-continent.