张帆, 王彦斌, 杨崇辉, 杜利林, 苑鸿庆. 河北赞皇杂岩官都群碎屑沉积岩锆石SHRIMPU-Pb定年及其地质意义[J]. 地质通报, 2019, 38(8): 1335-1343.
    引用本文: 张帆, 王彦斌, 杨崇辉, 杜利林, 苑鸿庆. 河北赞皇杂岩官都群碎屑沉积岩锆石SHRIMPU-Pb定年及其地质意义[J]. 地质通报, 2019, 38(8): 1335-1343.
    ZHANG Fan, WANG Yanbin, YANG Chonghui, DU Lilin, YUAN Hongqing. SHRIMP U-Pb zircon dating of clastic sedimentary rocks of the Guandu Group, Zanhuang Complex, Hebei Province, and its geological significance[J]. Geological Bulletin of China, 2019, 38(8): 1335-1343.
    Citation: ZHANG Fan, WANG Yanbin, YANG Chonghui, DU Lilin, YUAN Hongqing. SHRIMP U-Pb zircon dating of clastic sedimentary rocks of the Guandu Group, Zanhuang Complex, Hebei Province, and its geological significance[J]. Geological Bulletin of China, 2019, 38(8): 1335-1343.

    河北赞皇杂岩官都群碎屑沉积岩锆石SHRIMPU-Pb定年及其地质意义

    SHRIMP U-Pb zircon dating of clastic sedimentary rocks of the Guandu Group, Zanhuang Complex, Hebei Province, and its geological significance

    • 摘要: 新太古代-古元古代表壳岩系在华北克拉通广泛发育,在赞皇地区也出露有较典型的中低级变质的火山-沉积岩系,即从原赞皇群解体出来的官都群,其形成时代和成因目前仍有争议。官都群的主要岩石组合为变基性火山岩(包括角闪片岩和斜长角闪岩)、大理岩、石英片岩,以及一系列长英质副片麻岩等。对其中的长英质副片麻岩进行碎屑锆石定年研究,并结合前人已报道的碎屑锆石数据可知,碎屑锆石年龄主要峰值约为2.5Ga,部分样品出现2.0~2.2Ga的峰值。变质锆石记录主要有2个范围,分别为2.48Ga左右和1.85~1.9Ga,可能代表了2期不同的构造热事件记录。结合该地区近年来的研究,可以得到如下认识:①样品中存在形态完好的长柱状锆石,表明是近源沉积;②约2.48Ga的变质记录与核部岩浆锆石的年龄(约2.5Ga)非常接近,可能代表了物源区中酸性岩体侵位后遭受的一次构造热事件,而不代表沉积岩形成后遭受变质的记录,即沉积过程晚于2.48Ga;③官都群至少有一部分岩石组合形成于古元古代;④官都群可能是不同时代、不同岩性单元拼贴而成,需要进一步解体。

       

      Abstract: The Neoarchean-Paleoproterozoic supercrustal rocks as well as the Guandu Group from Zanhuang Complex have been widely reported in the whole North China Craton. The formation age and the environment of the Guandu Group are still controversial. Zircon SHRIMP U-Pb data of clastic sedimentary rocks of the Guandu Group, combined with previously available detrital zircon data, reveal that the majority of detrital ages are at~2.5Ga, with 2.0~2.2Ga peak for some samples. At least two metamorphic events were recorded, i.e., ~2.48Ga and 1.85~1.9Ga. Based on data obtained in this study as well as other studies of the Zanhuang Complex in recent years, some conclusions can be drawn as follows:① The well-preserved elongate prismatic morphology of some zircons implies that the source of depositional materials was not far away; ② The~2.48Ga metamorphic record is so close to the crystallization age of inner cores of zircons (~2.5Ga), probably suggests the existence of metamorphism that happened soon after the formation of the igneous rocks before the deposition of Guandu Group rocks, i.e., the deposition happened after~2.48Ga; ③ At least part of the Guandu Group was formed in Paleoproterozoic instead of late Archean; ④ The Guandu Group was probably not a continuous stratigraphic unit, but was composed of lithological units formed in different epochs and environments, and it thus should be disintegrated.

       

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