ABSTRACT

The Qiaotou Formation comprises the late Mesoproterozoic to early Neoproterozoic strata in southern Jilin and Liaoning Provinces at the eastern margin of the North China Craton (NCC). The depositional age of the formation is 1.1–0.9 Ga, as constrained from the ages of the youngest detrital zircons and later mafic intrusions. U-Pb age dating of detrital zircons yielded age peaks at 1.16, 1.58, and 1.74 Ga, and a minor peak of 2.47 Ga. The late Neoarchaean to Palaeoproterozoic detrital zircons were derived from the ca. 2.5 Ga Longgang and Liaonan blocks, ca.1.9 Ga magmatic/metamorphic rocks and late Palaeoproterozoic extensional-related magmatic rocks in NCC. The abundance of Mesoproterozoic zircon grains is less easy to explain. The possible source may represent (i) possibly concealed/vanished Grenvillian magmatic rocks in NCC, or (ii) derivation from the Qinling Microcontinent or (iii) Fennoscandian shield, or (iv) São Francisco–Congo Craton.

摘要

桥头组位于华北克拉通（NCC）东缘的吉林南部和辽宁省南部的中元古代晚期至新元古代早期地层。地层的沉积年龄为 1.1-0.9 Ga，受最年轻的碎屑锆石和后来的镁铁质侵入体年龄的限制。碎屑锆石的 U-Pb 年龄测年产生了 1.16、1.58 和 1.74 Ga 的年龄峰值，以及 2.47 Ga 的次要峰。新太古代晚期至古元古代碎屑锆石来自约。2.5 嘎龙岗、辽南地块，约1.9 嘎岩浆/变质岩和晚古元古代拉张相关的华北克拉通岩浆岩。中元古代锆石颗粒的丰度不太容易解释。可能的来源可能代表 (i) NCC 中可能隐藏/消失的 Grenvillian 岩浆岩，