| Xueling copper polymetallic deposit is located in the southern of dongchuan mining area.Previous studies have found that the characteristics of diabase are similar to those of Emeishan basalt,but there are few systematic studies on xueling diabase.Diabase of xueling is the main research of this thesis,the systematic studies based on the petrography,geochemistry,chronology and other aspects.Comparing with the geochemical characteristics of Emeishan basalt and discussing their relativity and geological significance.The major elements of Xueling diabase are low in silicon?SiO2=42.52%51.68%,with an average content of 47.80%?,low in total alkali?Na2O+K2O=2.75%6.09%,with an average content of 4.29%?,low differentiation index?DI=25.650.62,with an average content of 36.55?,and the rittman index?=1.229.49,?with an average content of 3.93?,indicating that it is a weakly differentiated alkaline iron titanium-rich basic rocks.As for trace elements,the large ion lithophilic elements such as Rb,Ba,Th,U etc and the rare earth elements such as La,Nd etc are generally enriched,while elements with high field strength such as Nb,Zr,Hf etc are slightly depleted.It shows that the crustal material participates in the formation of rocks.REE?excluding Y?=194.07×10-6281.97×10-6,LREE/HREE=5.149.49,the standardized distribution mode diagram of chondrite of rare earth elements is of right-leaning type,indicating that the heavy and light rare earth fractionation is obvious in the basic rocks of snow ridge.87Rb/86Sr=0.1840.498,87Sr/86Sr=0.705460.70823,slightly higher than the modern value of the original mantle.147Sm/144Nd=0.12620.1322,143Nd/144Nd=0.5124830.512597,slightly lower than the modern value of the original mantle.206Pb/204Pb=18.27119.936,207Pb/204Pb=15.62515.696,208Pb/204Pb=38.47140.018,these characteristic values can be determined from the crust and mantle mixing characteristics of the xueling basic rocks.Dating results of LA-ICP-MS zircon U-Pb of xueling diabase show that the age-weighted average of diabase 206Pb/238U is 242 Maħ28 Ma.The emplacement age of diabase is basically consistent with the main eruption period of Emeishan large igneous province.Xueling diabase is similar to Emeishan basalt in geochemical characteristics.The source area of magma is mantle plume.The sample model age with normal lead characteristics is 260-381 Ma,similar to Emeishan basalt eruption age,the Sr-Nd isotope characteristics,and the tectonic setting is mainly intraplate basalt.It is considered that the diabase of Xueling copper polymetallic deposit is related to Emeishan basalt,and the diabase is the product of contemporaneous magmatic activity of Emeishan basalt. |
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