U-Pb dating of Mesozoic igneous rocks from Hong Kong
U-Pb dating of Mesozoic igneous rocks from Hong Kong
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DOI：
10.1144/gsjgs.154.6.1067
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发表时间：
1997-11
影响因子：
2.7
通讯作者：
D. Davis;R. J. Sewell;S. Campbell
中科院分区：
文献类型：
--
作者：
D. Davis;R. J. Sewell;S. Campbell
本文对香港中生代深成岩和火山岩进行了22个新的锆石和独居石U-Pb年龄测定。研究表明，中侏罗世-下白垩世火山-侵入作用存在4个明显的时期：164.6 ±0.2 ~ 159.3 ± 0.3Ma、146.6 ±0.2 ~ 146.2 ± 0.2Ma、143.7 ±0.3 ~ 142.5 ± 0.3Ma和140.9 ±0.2 ~ 140.4 ± 0.2Ma。还从一个侵入体中获得了236.3 ± 0.8 Ma的独居石一致年龄，这是该领土已知的第一个中三叠世花岗岩。在这些岩石中，不一致的U-Pb数据投影到Concordia曲线上，给出了从早古生代到晚古生代的广泛继承年龄。一个捕虏晶锆石的一致年龄为1872 ±3 Ma。新的U-Pb年龄修正了花岗岩类Rb-Sr全岩年龄测定结果，并大大改善了侵入和喷出单元之间的对比。在许多分析的岩石中出现的继承成分表明，它们是从含有各种年龄成分的老地壳中衍生出来的，或者是通过老地壳喷发出来的，这些成分是原始火成岩或碎屑物质。
Twenty-two new zircon and monazite U-Pb ages have been obtained for Mesozoic plutonic and volcanic rocks of Hong Kong. These have revealed the existence of four distinct periods of Mid-Jurassic to Lower Cretaceous volcano-plutonism: 164.6 ±0.2 to 159.3 ±0.3 Ma, 146.6 ±0.2 to 146.2 ±0.2 Ma, 143.7 ±0.3 to 142.5 ±0.3 Ma, and 140.9 ±0.2 to 140.4 ±0.2 Ma. A concordant monazite age of 236.3 ± 0.8 Ma has also been obtained from one intrusive body representing the first known occurrence of a Mid-Triassic granitoid in the Territory. Among these rocks, discordant U-Pb data projected to the concordia curve have given a broad range of inheritance ages from early Phanerozoic to late Archaean. A xenocrystic zircon from one sample has yielded a concordant age of 1872 ±3 Ma. The new U-Pb ages have refined the results of recent Rb-Sr whole-rock age dating of the granitoid rocks and have considerably improved correlation between intrusive and extrusive units. The occurrence of inherited components in many of the analysed rocks indicates that they were derived from, or erupted through, older crust containing a wide variety of age components, either as primary igneous or detrital material.