Methods and results of sedimentary geological mapping of special issues in the Shangyi Basin, western Yanshan Mountain

The Yanshan movement was an important intra-continental orogenic movement in East China during the Late Mesozoic, causing extensive and significant influence. Although researchers have studied the Yanshan movement for nearly one hundred years and achieved lots of results, the intra-continental orogeny of the Yanshan orogenic belt remains a problem of much controversy. To tackle this problem, the authors chose the Shangyi Basin in western Yanshan Mountain to carry out 1:50000 special geological mapping. On the basis of the geological mapping, an integrated analysis of basin filling sequences, lithofacies, sedimentary environment and provenance was conducted to reconstruct lithofacies paleogeography, construct basin evolutionary model and discuss sedimentary response to the intra-continental orogeny of the Yanshan orogenic belt. A 1:50000 formation-facies lithofacies geological map was completed by the method of sedimentary lithofacies association mapping. The sedimentary evolution of the Shangyi Basin in the western Yanshan Mountain recorded the whole process of pre-orogenic extension, syn-orogenic compression and post-orogenic extension of the Yanshan orogenic belt.