扬子北缘白田坝组含锂细碎屑岩物源与沉积环境分析OA

[Objective]The discovery of lithium-mineralized bodies in multiple layers in the Permian to the Jurassic at the northern margin of the Yangtze Block is of great significance to the investigation,development and utilization of sedimentary lithium resources.This study aims to ascertain the nature and tectonic setting of the parent rocks in the source area of the lithium-bearing(lithium-rich)fine clastic rocks of the Jurassic Baitianba Formation,and to prelim-inarily discuss the influence of paleoenvironmental conditions on lithium enrichment.[Methods]Detailed petrologi-cal investigations were conducted on the typical lithologies within the formation,along with elemental geochemical analyses focusing on the lithium-bearing(lithium-enriched)fine clastic rocks.[Results]The oxide discriminant function graph of the main elements and the LaN/YbN-ΣREE,K2O-Rb and La/Th-Hf diagrams indicate a mixed prove-nance of igneous,sedimentary and metamorphic rocks.The oxide discriminant function graph of the main elements,together with La-Th,Ti/Zr-La/Sc,La-Th-Sc,Th-Sc-Zr/10 and Th-Co-Zr/10 diagrams,show that the tectonic back-ground of the sedimentary period was an active continental margin,and some source rocks were formed in a continen-tal island arc environment.Lithium probably originated from arc magma material.Ga,Sr/Ba,Sr/Cu,C,CIA,U/Th,Ni/Co and other paleoenvironmental indicators indicate that the lithium-bearing rocks were deposited in a weakly oxi-dizing freshwater environment in a warm,humid climate.The A-CN-K and Th/Sc-Zr/Sc diagrams show that the parent rocks underwent moderate to intense weathering when the debris was first deposited.[Conclusions]The comprehen-sive study found that lithium enrichment was only superficially influenced by ancient salinity and ancient reduction-oxidation conditions.Rather,the warm humid climate was conducive to the formation of clay minerals,which in-creased the clay-mineral content of Li-bearing(Li-rich)fine clastic rocks and determined the extent of lithium enrich-ment.