Element Migration Mechanism And Prospecting Signs Of The Jiajika Pegmatite-Type Lithium Deposit In Sichuan Province

Technological revolutions such as new energy and new materials have brought about a rapid increase in the global demand for lithium resources.It is of great practical economic and long-term strategic significance to improve China's lithium resource reserves and their degree of protection.The Jiajika deposit is the largest-sized rare metal pegmatite deposit in China,which is characterized by shallow burial,rich grades with associated elements and beneficially mining.It is a typical representative of rare metal pegmatite deposits produced in large numbers in the western Sichuan.Studying the geochemical element combination characteristics of this deposit and its migration and dispersion mechanism in the supergene environment can provide methodological,technical guidance and significant reference to finding rare metal pegmatite-type lithium deposits in areas with similar geological conditions but low working degree in western Sichuan.The statistical data analysis of 39 elements shows that the associated element indicators of regional geochemical survey is Li-Be-B-Sn.Studies on te sample media grain size and migration of dranage system sediments in the Meka area show that the best sample grian size for the measurement of stream sediments for reginal geochemical surveyin the alpine landscape area of the Western Sichuan Plateau is-40 mesh.The indicator element migration distance(that is,the abnormal distribution range along the water system)is up to 6km,which can be traced to mineralization sources according to regional geochemical anomalies.Tests show that the measurement data of sediments at 1 point/4km~2 show the obvious Li-Be-B-Sn-Rb-Cs multi-element assemblage anomaly in the concentration center.When the sampling density is diluted to 1 point/9km,an obvious Li-Be-B-Sn-Cs abnormal combination can be obtained,but the abnormal intensity will reduce.The geochemical characteristics of granite rock,pegmatite vein ore,and corresponding soil and water system sediments in the Jiajika deposit are studied.It is found that the REE and Li contents in different lithological rocks in the Jiajika deposit are negatively correlated,which corresponds to the conditions in other regions,that is,the lower the total amount of rare earth elements of different mineralized rare metal pegmatite(vein),the higher the content of lithium element and the amount of lithium mineral resources.Studies have shown that the occurrence status of mineralization indicator elements in different rocks are different,which lead to differences in the geochemical behavior of elements during weathering.For example,the content of Li,Sn,and Be in granite is low and they mainly present in muscovite in the homomorphism form or super-obvious-micro unstructured mixed form,which is more likely to be lost during weathering.And these elements mainly exist as independent minerals in pegmatite ore,where Li mainly occurs in spodumene and lepidolite,and Be exists in the form of beryl,Sn exists in the form of cassiterite.The soil and stream sediments have inherited the geochemical characteristics of the source rock to a certain extent.The indicator element combination for regional mineralization in rock geochemical measurement of the mining area is Li-Be-B-Sn-Rb-Cs-Nb-Ta,for soil geochemical measurement of the mining area is Li-Be-B-Sn-Rb-Cs-Nb,for water-based sediments geochemical measurement of the mining area is Li-Be-B-Sn-Rb-Cs.