Petrologic and zircon U–Pb geochronological characteristics of the pelitic granulites from the Badu Complex of the Cathaysia Block, South China
Petrologic and zircon U–Pb geochronological characteristics of the pelitic granulites from the Badu Complex of the Cathaysia Block, South China
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华南华夏地块八都杂岩泥质麻粒岩的岩石学和锆石U-Pb年代学特征
DOI：
10.1016/j.jseaes.2018.02.017
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发表时间：
2018-06
影响因子：
3
通讯作者：
Cui Xiahong
中科院分区：
文献类型：
--
作者：
Zhao Lei;Zhou Xiwen;Zhai Mingguo;Liu Bo;Cui Xiahong
华南地块印支期造山作用的认识，由于风化作用强、覆盖层厚，一直存在争议和困难。高温（HT）和高压（HP）变质岩related.to这个造山带被认为是不存在的，直到最近发现榴辉岩和麻粒岩相变火成岩，作为透镜体出现在八都杂岩的变沉积岩中。然而，这些变质沉积岩的变质状态仍然不清楚。此外，在八都杂岩中还没有HT泥质麻粒岩的年代学资料。本文介绍了新发现的蓝晶石石榴子岩、片麻岩、辉石石榴子岩和HT泥质麻粒岩（硅线石石榴子岩）的岩石学特征和锆石年代学结果。HT泥质麻粒岩的矿物组合为石榴子石+硅线石+三元长石+斜长石+石英+黑云母，蓝晶石石榴子片麻岩的矿物组合为蓝晶石+三元长石+石榴子石+硅线石+斜长石+石英+黑云母，辉石石榴子片麻岩的矿物组合为石榴子石+黑云母+辉石+斜长石+三元长石+石英。在这些泥质岩中，石榴子石颗粒周围均可见减压日冕。典型的麻粒岩相矿物组合和反应结构表明，这些岩石经历了高压麻粒岩相变质作用，并沿沿着的P-T环叠加减压作用。综合U-Pb.dating和REE分析的结果表明，与来自花岗岩源（通常> 1000球粒陨石）的碎屑锆石相比，来自亏损重REE源（100- 50.0球粒陨石）的变质锆石的生长。高压麻粒岩中的变质锆石没有或表现出微弱的负Eu异常，这可能表明榴辉岩相条件下的锆石过度生长。锆石增生年龄为250 ~ 235 Ma，表明这些表壳岩的高压麻粒岩相（榴辉岩相）-麻粒岩相变质作用发生在早-中三叠世。根据HP麻粒岩相泥质岩的存在，推测印支期造山运动中存在着明显的下冲作用，将这些表壳岩引入地壳下部。
The recognition of the Indosinian Orogeny in the South China block has been controversial and difficult because.of strong weathering and thick cover. High temperature (HT) and high pressure (HP) metamorphic rocks related.to this orogeny were considered to be absent from this orogenic belt until the recent discovery of eclogite and.granulite facies meta–igneous rocks, occurring as lenses within the meta–sedimentary rocks of the Badu.Complex. However, metamorphic state of these meta–sedimentary rocks is still not clear. Besides, there have.been no geochronological data of HT pelitic granulites previously reported from the Badu Complex. This paper.presents petrographic characteristics and zircon geochronological results on the newly discovered kyanite garnet.gneiss, pyroxene garnet gneiss and the HT pelitic granulites (sillimanite garnet gneiss). Mineral assemblages are.garnet+sillimanite+ternary feldspar+plagioclase+quartz+biotite for the HT pelitic granulite, kyanite+.ternary feldspar+garnet+sillimanite+plagioclase+quartz+biotite for the kyanite garnet gneiss,.and garnet+biotite+pyroxene+plagioclase+ternary feldspar+quartz for the pyroxene garnet gneiss, respectively..Decompressional coronas around garnet grains can be observed in all these pelitic rocks. Typical.granulite facies mineral assemblages and reaction textures suggest that these rocks experienced HP granulite.facies metamorphism and overprinted decompression along a clockwise P–T loop. Results from integrated U–Pb.dating and REE analysis indicate the growth of metamorphic zircons from depleted heavy REE sources (100–50.chondrite) compared with detrital zircons derived from granitic sources (typically > 1000 chondrite)..Metamorphic zircons in HP granulite exhibit no or subdued negative Eu anomalies, which perhaps indicate.zircon overgrowth under eclogite facies conditions. The zircon overgrowth ages range from 250 to 235 Ma,.suggesting that HP granulite (eclogite) to granulite facies metamorphism of these supracrustal rocks occurred in.the Early–Middle Triassic. Based on the presence of HP granulite facies pelitic rocks, it is inferred that significant.underthrusting was involved during the Indosinian Orogeny which introduced these supracrustal rocks to lower.crustal levels.
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影响因子：
--
作者：
Xiwen Zhou;C. Wei;Y. Geng;Lifei Zhang
通讯作者：
Xiwen Zhou;C. Wei;Y. Geng;Lifei Zhang
影响因子：
6.1
作者：
Yuejun Wang;W. Fan;Guowei Zhang;Yanhua Zhang
通讯作者：
Yuejun Wang;W. Fan;Guowei Zhang;Yanhua Zhang
影响因子：
4.5
作者：
Geisler, Thorsten;Schaltegger, Urs;Tomaschek, Frank
通讯作者：
Tomaschek, Frank
华南华夏地块八都杂岩早中生代退变榴辉岩和镁铁质麻粒岩：岩石学及构造意义
影响因子：
6.1
作者：
Zhao Lei;Zhai Mingguo;Santosh M.;Zhou Xiwen
通讯作者：
Zhou Xiwen
DOI：
10.1029/sc007p0001
发表时间：
2013-03
期刊：
--
影响因子：
--
作者：
F. Spear
通讯作者：
F. Spear