First SHRIMP zircon U-Pb ages for Hutuo Group in Wutaishan: Further evidence for Palaeoproterozoic amalgamation of North China Craton
First SHRIMP zircon U-Pb ages for Hutuo Group in Wutaishan: Further evidence for Palaeoproterozoic amalgamation of North China Craton
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DOI：
10.1360/03wd0220
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发表时间：
2004
影响因子：
--
通讯作者：
S. Wilde;Guochun Zhao;Kaiyi Wang;M. Sun
中科院分区：
文献类型：
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作者：
S. Wilde;Guochun Zhao;Kaiyi Wang;M. Sun
五台山台怀以南8 km处的滹沱群火山岩和沉积物变质序列中，长英质凝灰质岩石含有两个锆石群。SHRIMP 207 Pb/206 Pb加权平均年龄分别为2180 ±5 Ma和2087 ±9 Ma。较老的年龄与五台山大瓦梁花岗岩的年龄相差不大，并被认为来自类似的地壳岩浆源。新的年龄是在误差范围内的变沉积物和变火山岩的湾子表壳岩和南营花岗质片麻岩在相邻的富平杂岩，并解释为火山作用的年龄在滹沱群。这些数据表明：（1）滹沱群的时代为古元古代而非太古代;（2）五台杂岩和阜平杂岩的火山作用和沉积作用是同时代的。因此，沉积作用在这个时候是广泛的，并可能反映沉积沿着一个不断发展的大陆边缘，最有可能的是中国北方东部陆块的西部边缘。火山作用的年龄为2087 ±9 Ma，表明其变形变质作用发生在这一时期之后。这进一步支持了近年来其他研究所获得的证据，即五台山地区的主要构造活动发生在吕梁造山运动期间的~ 1.8Ga。这一造山运动导致了华北板块东西两块体的碰撞，并构成了全球超大陆合并事件的一部分。
A felsic tuffaceous rock, obtained from a metamorphosed sequence of volcanics and sediments of the Hutuo Group, 8 km south of Taihuai in Wutaishan, contains two zircon populations. These record SHRIMP207Pb/206Pb weighted mean ages of 2180 ±5 Ma and 2087 ±9 Ma, respectively. The older date is within error of the age of the Dawaliang Granite in Wutaishan and is considered to be derived from a similar crustal magmatic source. The younger date is within error of reported ages from metasediments and meta-volcanics of the Wanzi supracrustal rocks and the Nanying granitic gneisses in the adjacent Fuping Complex and is interpreted to be the age of volcanism in the Hutuo Group. These data establish that: (1) the Hutuo Group is Paleoproterozoic and not Archean in age and (2) the volcanism and sedimentation were coeval in the Wutai and Fuping complexes. Sedimentation was therefore widespread at this time and possibly reflects deposition along an evolving continental margin, most likely the western margin of the Eastern Block of the North China Craton. The age of 2087 ±9 Ma for volcanism in the Hutuo Group means that it must have been deformed and metamorphosed after this time. This further supports the evidence, obtained from other recent studies, that the main tectonism in the Wutaishan area occurred at ~1.8 Ga during the Lüliang orogeny. This orogeny resulted in the collision of the Eastern and Western blocks of the North China Craton and formed part of a global supercontinental amalgamation event.