豫西秦岭杂岩变质带的分布及主期变质时代的限定

发布时间：2018-04-09 22:34

本文选题：变质带　切入点：锆石测年　出处：《岩石学报》2016年07期

【摘要】：豫西秦岭杂岩中变质分级可呈与造山带大致平行的带状分布,从两侧向中心变质级别升高,尤其南侧分带明显:由南向北,依次为黑云母带-石榴子石带-蓝晶石带-夕线石带,直至斜方辉石带,而不是整体上经历了麻粒岩相变质作用。局部发生的麻粒岩相变质未见明显向角闪岩相变质转化的退变结构。通过几种岩石的锆石LA-MC-ICPMS测年研究,多数样品中的锆石经受了后期强烈的改造,同位素体系或多或少被重置。尽管如此,侵位花岗岩和伟晶岩年龄限定了主期变质作用的时代应老于484±3Ma,并可能与早期的榴辉岩相变质作用在演化上有联系。主期变质(不包括榴辉岩相变质)性质与经典的巴罗式变质带可以对比;此外,研究区未经历明显的地壳增厚,与高喜马拉雅结晶岩系类似,秦岭杂岩可能经历了中、下地壳物质沿隧道流上升过程。
[Abstract]:The classification of metamorphic rocks in Qinling Mountains complex orogenic belt and is roughly parallel to the zonal distribution, increased from two sides to the center of modification level, especially on the south side of zoning is clear: from south to north, followed by garnet biotite belt belt belt - kyanite sillimanite zone, until orthopyroxene, rather than on the whole experienced granulite facies metamorphism. The local occurrence of granulite facies to amphibolite facies metamorphic transformation had no obvious degeneration structure. The zircon LA-MC-ICPMS dating on some rocks, most samples in zircon undergo later strong reformation of isotope system have been reset. Nevertheless, the emplacement of granite and pegmatite the age limit the main metamorphism in the age of 484 + 3Ma, and may be associated with early eclogite facies metamorphism in the evolution of a relationship. The main phase metamorphism (excluding eclogite facies metamorphism) with classical properties The Barro metamorphic belt can be compared. In addition, the study area did not experience obvious crustal thickening, similar to the high Himalaya crystalline rock series. The Qinling Mountains complex may have experienced the rising process of medium and lower crustal materials along the tunnel.

【作者单位】：中国地质科学院地质研究所;中国地质科学院地质力学研究所;中国地质大学;
【基金】：中国地质调查局地质调查项目(121201102000150009-4、121201102000150012)资助
【分类号】：P588.3

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