Keywords

The North China Platform, measuring ca. 1000 km N–S and 1500 km E–W, is an epeiric platform developed on the stable Sino–Korean Craton (Meng et al. 1997). Sedimentation on the North China Platform started in the early Cambrian and continued until the Middle to Late Ordovician, forming a ~1800-m-thick succession of mixed carbonate and siliciclastic sediments (Meng et al. 1997) unconformably overlain by late Palaeozoic shallow marine and continental deposits.

Shandong Province is located in the central part of the North China Platform. The Cambrian succession is superbly exposed in this region, which has served as a standard for the Cambrian lithology of North China (Chough et al. 2010). Six lithostratigraphic units (the Liguan, Zhushadong, Mantou, Zhangxia, Gushan, and Chaomidian formations, in ascending order) have been recognized for the Cambrian succession, which unconformably overlies Precambrian granitic gneiss or metasedimentary rocks. Twenty-one trilobite biozones have been identified from this Cambrian succession (Fig. 1).

Fig. 1
figure 1

Lithostratigraphic and biostratigraphic summary of Shandong Province, China and the Taebaeksan Basin, Korea, with representative trilobites occurring in common to both regions. A–L representative trilobites from Shandong Province. M–X representative trilobites from the Taebaek Group, Taebaeksan Basin, Korea

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The tectonic reconstruction and stratigraphic correlation of the Palaeozoic basins indicate that the Taebaeksan Basin, Korea was located at the eastern margin of the North China Platform, ca. 900 km from present-day Shandong Province (Choi and Chough 2005). The Cambrian succession in the Taebaeksan Basin consists of six lithostratigraphic units, namely the Jangsan/Myeonsan, Myobong, Daegi, Sesong, Hwajeol, and Dongjeom formations, in ascending order, with the Cambrian–Ordovician boundary lying within the Dongjeom Formation. Seventeen biozones have been recognized from these strata (Fig. 1).

Although the Cambrian trilobite faunal assemblages in both regions are known to be generally similar (Choi and Chough 2005), the biostratigraphic schemes were independently developed in the two regions. As a result, a detailed correlation of the two regions has been hardly attempted. Recently, the Cambrian successions in both Shandong Province and the Taebaeksan Basin have been intensively studied in terms of palaeontology and sedimentology, and a precise biostratigraphic and lithostratigraphic correlation of the two regions is now possible. The comparison reveals that carbonate production was more active in Shandong Province, whereas coarse-grained siliciclastics were deposited more voluminously in the Taebaeksan Basin during the Cambrian. The most notable feature from the correlation is the diachroneity of the major lithological boundary. Both the Zhangxia Formation of Shandong Province and the Daegi Formation of the Taebaeksan Basin represent the microbial carbonate-dominant succession in the Cambrian Series 3 of the North China Platform. However, the biostratigraphy indicates that the microbial carbonate-dominant facies appeared earlier in Shandong Province than in the Taebaeksan Basin (Fig. 1). The abrupt cessation of the microbial carbonate accumulation, followed by deposition of shale-dominant lithology (the Gushan Formation in Shandong Province and the Sesong Formation in the Taebaeksan Basin) also occurred earlier in Shandong Province (Fig. 1). Identification of such diachronous lithological boundaries within the same platform will eventually help us to understand the dynamics of sedimentation processes as well as the palaeoenvironmental changes at a basin scale.