The Geological Characteristics And The Metallogenic Evaluation Of Changren Basic-ultrabasic Intrusion In Jilin Province

The basic-ultrabasic intrusion in the changren area of Jilin province is located in the eastern part of the central Asian orogenic belt,spanning two geotectonic units with different properties: the north China craton and the xingmeng orogenic belt.The basic-ultrabasic intrusion is located in the active orogenic belt north of gudonghe fault,widely distributed in the NW-NNW direction,has superior metallogenic geological conditions.A large amount of Cu-Ni(PGE)deposits(ore occurrences)have been discovered here in the past years.The copper-nickel deposits in this area have been studied deeply by predecessors.However,there is a lack of systematic comparative study on the differences between ore-bearingand non-ore-bearing basic-ultrabasic intrusion.This paper selects basic-ultrabasic intrusions in changren area and typical ore-bearing basic-ultrabasic intrusions in China,aiming at ore-bearing evaluation of the intrusions by comparing the intrusions system aticly in macroscopic geology,chronology,petrology,mineralogy,petrogeochemistry,mineral and geochemistry,analysing the difference between ore-bearing intrusions and ore-free intrusions.Through analysis of Changren-NO.1,Changren-NO.1 and Changren-NO.37 basic-ultrabasic intrusions,we try to evaluate their mineralization potential.The main results are as follows:1.Study on the basic geology,petrology,geochemistry and physical geography characteristics of Changren-NO.1,Changren-NO.11,and Changren-NO.37 basic-ultrabasic intrusions,enriching the basic date of intrusions in the study area.2.Analysis and comparison on the basic geological and geochemical characteristics of typical ore-bearing basic-ultrabasic intrusion,summarizing the ore-bearing evaluation of the basic-ultrabasic intrusion in Changren area:The formation of deep fault structure controls the development of ore-bearing basic-ultrabasic intrusion.The ore-forming basic-ultrabasic intrusion has relatively small outcrop area,sufficient magmatic differentiation and diverse rock types,and the higher the degree of partial melting,the better the mineralization;The higher the degree of partial melting of basic-ultrabasic intrusion is,the more favorable it is for mineralization.The ore-forming basic-ultrabasic intrusions often have strong alteration,and there are many water-bearing minerals such as mica and amphibole.The nickel-pyrite-pyrrhotite-chalcopyrite mineral assemblages developed in rocks are favorable for mineralization.The content of MgO in ore-bearing basic-ultrabasic intrusion is mostly between 8 and 30%,and the m/f ratio is mostly between 2 and 6.5.The degree of REEs distribution of ore-forming basic-ultrabasic intrusions is right-dip curve;The basic-ultrabasic intrusions formed in the Indosinian Epoch have great metallogenic potential.3.Use the ore-bearing evaluation,evaluating the mineralization potential of several basic-ultrabasic intrusions in Changren area:The Changren NO.1 intrusion shows certain metallogenic potential,but it still needs further verification;The Changren NO.11 intrusion is controlled by the secondary fault,which shows good magmatic differentiation and well developed alteration.The geochemical characteristics of the intrusion are very similar to those of the typical large ore-bearing rock mass in China,therefore,it has the value of further research;The Changren NO.37 intrusion shows certain ore-bearing potential in macroscopic geological characteristics,magmatic differentiation and lithofacies zoning,but it is different from the typical ore-bearing intrusions in terms of alteration,mineralization characteristics,petrogeochemistry and age of intrusion formation.