NEW ADVANCES IN THE STUDY OF LATE NEOGENE STRATIGRAPHY IN THE LLIANG MOUNTAIN
LI Jian-xing~ 1) 2) , YUE Le-ping~ 1) , XU Yong~ 1) , SUN Bo~ 1) , SUN Lu~ 1) and WANG Xiao-yong~ 2) 1) State Key Laboratory of Northwest University Continental Dynamics,Xi’an 710069;2) Xi'an Centre of Geology Survey, China Geology Survey, Xi’an 710054
Based on the study of the Liulin and Baode sections in the western Lüliang Mountain, we conclude that the Baode Formation at the Weijiawa section in Liulin, Shanxi province can be correlated with the Baode section. The sandy gravel layer of the lower Baode Formation is aqueous deposits, but the upper sequence of brownish red clay and brownish yellow calcite nodules are considered to be eolian clay layers. The middle part is thought to be the transition zone from the lower aqueous deposits to upper eolian deposits. According to The Stratigraphic Guide of China and Its Explanation, a lithostratigraphic unit (e.g., formation) should consist of strata of consistent lithology, lithothcies, metamorphic grade. The lower aqueous deposits and the upper aeolian red clay can not be regarded as a rock assemblage that was formed in a uniform environment. Thus,it is inappropriate to use a single formation to define the beds formed in different environments. We suggest that the original definition of the Baode formation be reinstated. The lower sandy gravel deposits should be classified as the Luzigou Formation, roughly equivalent to the "Luzigou System" or "Luzigou Conglomerate". The upper eolian deposits belong to the Baode Formation, as it was originally defined. In this definition, the Luzigou Formation represents alluvial fan deposits which unconformably overlies the pre-Cenozoic bedrock but conformably underlies the Baode red clay. The Baode Formation includes all eolian deposits between the underlying Luzigou Formation and the overlying Jingle Formation.