Paper No. 13
Presentation Time: 4:30 PM


ZHAO, Yue1, ZHANG, Shuanhong2, YANG, Zhenyu1 and PEI, Junling3, (1)Institute of Geomechanics, CAGS, 11# Min-Da-Nan-Lu, Beijing, 100081, China, (2)Institute of Geomechanics, 11# Zhong-Yang-Min-Zu-Da-Xue-Nan-Lu, Beijing, 100081, China, (3)Institute of Geomechanics, Chinese Academy of Geological Sciences, 11 Minzu-Daxue Nan Lu Street, Haidian District, Beijing, 100081, China,

North China Craton (NCC) was once a part of Paleoproterozoic–Mesoproterozoic supercontinent Columbia /Nuna, including Siberia, Laurentia, Baltica and so on(Zhang et al., 2009; Evans & Mitchell, 2011; Chen et al., 2013). Its lower cover sequence, known as the Changcheng, Jixian and Qingbaikou systems considered previously as typical Mesoproterozoic to Neoproterozoic in NCC from ca. 1800 Ma to 800 Ma., has been proven to be part of Mesoproterozoic from ca. 1655 Ma to 1325 Ma. In this presentation we show lines of evidence that deposition of the Changzhougou Formation, the bottom formation of the Changcheng system started around 1655 Ma while whole sequence terminated prior to emplacement of large volumes of diabase sills into the upper Mesoproterozoic ca. 1325 Ma, when Breakup of North China Craton from Columbia /Nuna occurred.

Emplacement of large volumes of diabase sills into the upper Mesoproterozoic, the Wumishan, Tieling and Xiamaling Formations in the ascending order around 1325 Ma (Zhang et al., 2009; 2012, and our new data) demonstrates not only breakup of NCC but also termination of the sequence, which is much similar to breakuping of Gondwana and emplacement of large volumes of thick Ferrar dolerite sills in the Transantarctic Mts. at the earliest Middle Jurassic, posterior to Beacon Supergroup sedimentation. SHRIMP U-Pb dating of K-bentonite beds and volcanic layers in the Xiamaling Formation yielded ages at 1368±12 Ma(Gao et al., 2007) and 1372±18 Ma (Su et al., 2010), in the Tieling Formation yielded age at 1437±21 Ma (Su et al., 2010), in the Gaoyuzhuang Formation yielded ages at 1560±5 Ma and 1559±12 Ma (Li et al., 2010), in the Dahongyu Formation yielded ages at 1622±23 Ma(Lu et al., 2008) and 1626±9 Ma (Gao et al., 2008), in the Tuanshanzi Formation yielded age at 1637±15 Ma (this presentation). Combined with zircon U-Pb LA-MC-ICPMS dating of a granite porphyry dyke intruded into the highly metamorphosed basement rocks and a weathering rapakivi granite overlain by the Changzhougou Formation, which gave ages at 1673±10 Ma (Li et al., 2011) and 1682±20 Ma (He et al., 2011) respectively, we infer the base age of the Mesoproterozoic sequence is ca. 1655 Ma. The sequence can be correlated with those in Columbia members, e.g., Siberia and had the same Paleomagnetic poles in Paleo-Mesoproterozoic (Chen et al., 2013).