U–Pb dating of serpentinization: hydrothermal zircon from a metasomatic rodingite shell (Sudetic ophiolite, SW Poland)
U–Pb dating of serpentinization: hydrothermal zircon from a metasomatic rodingite shell (Sudetic ophiolite, SW Poland)
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DOI：
10.1016/j.chemgeo.2003.10.005
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发表时间：
2004-02
期刊：
影响因子：
3.9
通讯作者：
E. Dubińska;P. Bylina;A. Kozłowski;W. Dörr;K. Nejbert;Janina Schastok;C. Kulicki
中科院分区：
文献类型：
--
作者：
E. Dubińska;P. Bylina;A. Kozłowski;W. Dörr;K. Nejbert;Janina Schastok;C. Kulicki
丰富的锆石颗粒被发现在一个交代绿泥石-corrensite（三八面体规则间层蒙脱石/蒙皂石）壳，周围的rodingite从Jordanów-Gogogoów（JG）蛇纹岩Gulf（苏台德蛇绿岩，波希米亚地块）。锆石颗粒具有两种类型的原生流体包裹体，包含液体CO2或水溶液。包裹体被用来指定锆石形成的P-T条件（270-300 °C，约100 ° C）。1 kbar），使用交叉等容线法。磨掉的单颗粒锆石U-Pb年龄为400+4/−3 Ma，这被解释为锆石结晶的年龄。这种锆石是在rodingitization过程中形成的，即，与蛇纹岩化作用直接相关的交代作用，从而提供了对早期蛇纹岩化作用直接测年的机会。来自Jordanów-Gogoów火山岩的锆石年龄与奥利弗等人[J. Geol. Soc.（Lond.）150（1993）355]。Ce异常结合苏铁蛇绿岩中镁铁质岩绿片岩相变质的矿物学记录，表明Pin等[Lithos 21（1988）195]的Sm-Nd全岩同位素数据（353±21 Ma）可能代表了后期变质事件的年龄。
Abundant zircon grains were found within a metasomatic chlorite–corrensite (trioctahedral regularly interstratified chlorite/smectite) shell that surrounds rodingite from the Jordanów–Gogołów (JG) serpentinite massif (Sudetic ophiolite, Bohemian Massif). The zircon grains bear two types of primary fluid inclusions containing either liquid CO2or aqueous solutions. The inclusions were used to assign the P–T conditions of the zircon formation (270–300 °C, ca. 1 kbar), using the crossed-isochore method. Abraded single zircon grains give a U–Pb age of 400+4/−3 Ma, which is interpreted as the age of zircon crystallization. This zircon formed during rodingitization, i.e., a metasomatic process directly connected with the serpentinization and thus provides the opportunity of direct dating of the early serpentinization process. The zircon age from the Jordanów–Gogołów massif is consistent with the crystallization age of metagabbro protoliths from the Sudetic ophiolite as determined by Oliver et al. [J. Geol. Soc. (Lond.) 150 (1993) 355]. A Ce anomaly, combined with the mineralogical record of greenschist facies metamorphism of the mafic rocks from Sudetic ophiolite, suggests that the Sm–Nd whole-rock isotopic data of Pin et al. [Lithos 21 (1988) 195] (353±21 Ma) possibly characterize the age of later metamorphic event.