Abstract:

Various types of lacustrine shale and laminated carbonate rock are extensively developed in Eogene of Jiyang depression. Observation and analysis under microscope of more than 300 shale thin-sections show that these lacustrine shale and laminated carbonate rock are all composed of three basic laminae which are organic-rich laminae (i.e., organicrich clay mineral laminae), aphanitic carbonate laminae and clay laminae. According to the difference of laminaecombination and proportion, seven types of lacustrine shale and laminated carbonate rock can be systematically classified, which are black shale, calcareouslaminated shale, organic-rich laminated shale, mud shale, calcareous shale, laminated muddy limestoneand laminated limestone. Meanwhile, based on the laminae component, a triangular genetic classification scheme is alsoproposed. Since different laminae are formed in different ancient lake conditions, the proposed classification scheme canindicatetheir laminae composition and genesis.

Key words: shale, laminaecombination, couplet, genetic classification, Jiyang depression