滇中地区梁山组黏土岩锂富集作用分析及找矿预测

LITHIUM ENRICHMENT IN THE CLAY ROCKS OF LIANGSHAN FORMATION AND PROSPECTING PREDICTION IN CENTRAL YUNNAN PROVINCE

滇中地区中二叠统梁山组富锂黏土岩分布于梁山期滇中古陆东侧河口湾、滨海平原沼泽区的泥坪带.梁山组黏土岩由4种岩性类型组成:灰-灰褐色含铁铝土(矿)岩、灰白杂红色高岭石黏土岩、灰-灰绿色黏土岩、灰黑-黑色水云母碳质黏土岩.研究发现,半咸水向咸水转变、弱氧化-还原、低能、滞留局限的古地理环境有利于形成富锂黏土岩.在稳定的大地构造环境,温暖、潮湿的古气候,丘陵为主的古地形条件下,滇中古陆的寒武系—泥盆系镁质碳酸盐岩在次生风化作用下形成的富锂黏土,经过搬运、沉积作用形成富锂黏土岩.在昆明市东川-富民、玉溪市红塔-建水、丽江市永胜-宁蒗地区具较好的富锂黏土岩找矿潜力.

The Li-rich clay rocks of Middle Permian Liangshan Formation in central Yunnan Province are distributed in the mudflat zone of estuary and coastal plain swamp area on the east side of central Yunnan archicontinent during Liangshan Period.The clay rocks of Liangshan Formation are composed of four lithologic types,including gray-greyish brown ferric bauxite rock,grayish white-red kaolinite clay rock,gray-greyish green clay rock,and gray black-black hydromica carbonaceous clay rock.It is found that the paleogeographical environment of brackish water transition to saline water,weak oxidation-reduction,low energy and limited retention is conducive to the formation of Li-rich clay rocks.Under the stable tectonic environment and the condition of warm-humid paleoclimate and hilly paleoterrain,the Cambrian-Devonian magnesian carbonate rocks in central Yunnan archicontinent form the Li-rich clay by secondary weathering,and then Li-rich clay rocks through transport and sedimentation.Dongchuan-Fumin of Kunming,Hongta-Jianshui of Yuxi and Yongsheng-Ninglang of Lijiang are prospect areas for Li-rich clay rocks.