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Abstract: There is a broad consensus that the North China Craton formed by the amalgamation of the Western and Eastern Blocks along the nearly N-S trending Trans-North China Orogen. However, it still remains controversial whether the Western and Eastern Blocks collided at ~2.5Ga or ~1.85Ga. U-Pb ages and Hf isotopic data of detrital zircons from foreland basins in the Trans-North China Orogen can place rigorous constraints on this controversial issue. One of such foreland basins is represented by the Hutuo Group in the Wutai Complex in the middle sector of the Trans-North China Orogen. The sequences of the Hutuo Group range from lower basal conglomerates and sandstones (Doucun Subgroup), through clastic sediments, dolomites and meta-basalts (Lower Dongye Subgroup), phyllites and dolomites (Upper Dongye Subgroup), to coarse-grained sandstones and conglomerates at the top (Guojiazhai Subgroup), most of which contain large amounts of detrital zircons. The detrital zircons from the Doucun, Lower Dongye, Upper Dongye and Guojiazhai Subgroups yield concordant 207Pb/206Pb ages of 2.11–3.88Ga, 2.01–2.84Ga, 1.88–2.72Ga and 1.92–2.65Ga respectively, the majority with Neoarchean to Paleoproterozoic ages. The presence of ~1.88Ga detrital zircons in the Upper Dongye and Guojiazhai Subgroups indicates that they deposited at some time after ~1.88Ga. This is in accordance with collision between the Eastern and Western Blocks along the Trans-North China Orogen to form the North China Craton at ~1.85Ga. [Copyright &y& Elsevier]

This paper reports detrital zircon age distributions of meta-sedimentary rocks of the Gaofan, Hutuo and Dongjiao groups in the Wutai and Dongjiao areas of the North China Craton. Detrital zircons of a quartzite from the Gaofan Group are mainly ~2.5 Ga in age, with some ~2.7 Ga and older. A quartzite pebble from the basal conglomerate of the Hutuo Group is similar in detrital zircon age distribution to the quartzite of the Gaofan Group. For a meta-feldspar-quartz sandstone from the Dongjiao Group, the age of detrital zircons is mainly concentrated at ~2.5 Ga. No zircons older than 2.6 Ga have been identified, but with some being 1.84 Ga and 2.2-2.0 Ga in age. Combined with earlier studies, the following conclusions can be drawn: (1) The Gaofan Group is early Palaeoproterozoic in age and is much younger and unrelated to the late Neoarchaean Wutai granite-greenstone terrane, which it unconformably overlies. As such, the Gaofan Group is one of the oldest Palaeoproterozoic meta-sedimentary units in the North China Craton. (2) The Hutuo Group was deposited in the middle Palaeoproterozoic (2.14-2.09 Ga) on a continental basement, after the early Palaeoproterozoic Gaofan Group. (3) The Dongjiao Group was formed after 1.84 Ga, and probably belongs to the lower portion of the Changcheng System. (4) The detrital zircons from all the three groups show an obvious age peak of ~2.5 Ga, being sourced from the igneous rocks formed in the intense tectono-magma-thermal events at the end of Archaean in the North China Craton. [ABSTRACT FROM AUTHOR]