Geochemical characteristics of ore-bearing strata and their prospecting implications for the Longqiao-type iron deposit in Lujiang-Zongyang basin,Anhui Province,China

Longqiao iron deposit is a large deposit in Lujiang-Zongyang basin.The ownership of the ore-bearing strata in the deposit remains regarding right up to now.Based on systematic geological investigation of the spatial distribution of the ore-bearing strata and synthetically analysis of the structural styles on plane and profile for the ore-bodies,it is concluded that the ore-bearing strata is supposed to be the Middle Jurassic Luoling Formation in this region.Furthermore,minor element boron contents in the ore-bearing strata are close to them in terrestrial sediments.The REE geochemical characteristics of the ore-bearing strata are different from those of marine sediments,but are similar to those of lacustrine sediments,i.e.,low ∑REE,enrichment of LREE,Ce and Eu weak negative anomaly,and Y/Ho ratio 34.8.In addition,the characteristics of REE of sandstone in ore-bearing strata are also similar to those of the Middle Jurassic Luoling Formation.Geological and geochemical studies confirmed that the ore-bearing strata are the Middle Jurassic Luoling Formation and they are terrestial sediments.Combining with the recent exploration achievments,it is proposed that the southern part of Lujiang-Zongyang basin who contains these terrestial sediments is the good disrict to look for sedimentary type and superimposed-sedimentary type ore deposits.