SEDIMENTARY MODEL AND ORIGIN OF CONGLOMERATE IN THE SOUTHEASTERN MARGIN OF NEOGENE LONGCHUAN BASIN, WEST YUNNAN
Zhao Yongsheng;Chen Bake;Zhao Xikui; Kuang Pinghe; Shi Wenhua
Neogene conglomerates in the southeastern margin of Longchuan basin mainly consist of debris flow and channel conglomerates. The sedimentary model is in accordance with no channel alluvial fan for margin fault. The fans can be divided into three parts: lower, middle and upper.The lower fans mainly consist of debris flow conglomerates. Lithofacies combination areas follows: Gm Gb, Gm-F. The middle fans are composed of debris flow and channel conglomerates. The lithofacies combination is as follows:Ss-Gh-St,Ss-Gh-St,Ss-Sm-F, Gs-Gm-Sh-F. The upper fans are composed of water channel and swamp. There are coal layers in the swamp.Distribution frequency curves of clast size of conglomerates may indicate sedimentary environment. BTH and MPS of conglomerates show that the conglomerates are from debris flow.