Magmatic Evolution And Ore Bearing Property In The Laoheishan Area,Heilongjiang Province

The LaoHeishan area is located in the complex part of the Central Asia Mongolia tectonic domain and the coastal Pacific structure,holding in the Siberia plate,the North China plate and the Western Pacific plate,developing a large number of Mesoproterozoic to Mesozoic Magmatic Rocks,and recorded the process of magma evolution at different periods.In this study,the main magmatic rocks in late Jinning,Late Indosinian and Yanshannian period in the LaoHeishan area were investigated in the field,the study of indoor petrography and the whole rock main trace element geochemical analysis were carried out to reveal the process of regional magma evolution and to study the petrochemistry and microlithogeochemistry during the evolution of magma.Geochemical characteristics of elements are used to study the ore bearing property of magmatic rocks.Finally,a comparative study of typical ore deposits is conducted to demonstrate the correctness of the study of magmatic rocks and their ore bearing properties.The Late Indosinian period intrusive rocks were evolved from neutral to acid,from aluminous to peraluminous,calc alkaline calcium series,alkali rich and potassium rich;late Yanshannian period intrusive rocks are evolved from medium to acid to acid rocks and belong to peraluminous and high potassium calc alkaline series.It is rich in alkali and potassium.However,with the evolution of magma crystallization,two stages of magma show the trend of Fe enrichment to Ca and K enrichment.The REE distribution curves of magmatic in each period are near the same and are all right inclined,all belong to the light rare earth enrichment type,indicating that they are the product of the crystallization differentiation of the homologous magma,and the enrichment of the large ion lithogenous elements such as Rb,Ba,U,La,Nd,Zr and Hf and the loss of Nb,Nd,P and Ti,indicating that the magma may come from the enriched mantle.In the course of its evolution,there are crustal matter mixing effect,which has the characteristics of crust source and crust mantle mixed source.By studying the geochemical signs and trace elements geochemistry during magma evolution,the magma evolved from early to late,from neutral to acid,from rich Fe and Mg to alkali rich,especially in the rich K direction.However,with this evolution,the ore bearing properties of magma evolved from Au to Cu to Mo,and in different stages and orders.The rock mass formed by the segment has different mineralization types: the late Indosinian granodiorite porphyry is rich in Cu,and the late Yanshan granodiorite is rich in Cu and Mo.With the differentiation of magmatic crystallization,from early to late,the late Indosinian neutrophilic volcanic rock-subvolcanic rocks controlled the Jiu FoGou gold deposit.The late Indosinian granodiorite and granite diorite controlled the YangHuiDng Zi porphyry copper mine,and the late Yanshan emplacement of the granite diorite controlled the Kan ChuanGou copper molybdenum ore.The molybdenum copper deposit fully supports the research of the magmatic rock evolution and ore bearing property in the LaoHeishan area,and provides guidance for finding mineral deposits in the study area.