Geochronology,geochemical characteristics and genesis analysis of diorite in Gemalong,eastern East Kunlun
The Gemalong area is located in the southern part of the eastern section of the East Kunlun orogenic belt.The tectonic activity and magmatic activity in this area are strong.In this paper,LA-ICP-MS zircon U-Pb geochronology and whole-rock element composition of two granodiorites and two tonalite diorites are studied.The genetic types and magmatic source characteristics of the rocks are discussed,and the tectonic evolution environment of the diorites is analyzed.The results show that the diagenetic ages of two representative diorite samples are 405.3±1.1 Ma and 405.8±1.2 Ma,respectively,indicating that the diagenetic age is Early Devonian.The four diorite samples have the characteristics of high silicon,high aluminum,high alkali,poor calcium,poor magnesium and weak peraluminous,belonging to the weak peraluminous high potassium calc-alkaline series rock.The representative minerals of S-type granite are not developed in the four samples,and the Rb/Sr value is 0.32～0.43,which is less than 0.9,and the A/CNK value is 0.98～1.09,which is less than 1.1,which is consistent with the geochemical characteristics of I-type granite.By analyzing the La-La/Sm diagram and(Zr+Nb+Ce+Y)-(Na2O+K2O)/CaO diagram,combined with Nb/Ta,Zr/Hf,Nb/U,Rb/Sr,Ti/Y,Ti/Zr values,it can be concluded that the diorite in Gemalong area is formed by partial melting of crustal rocks,and may be accompanied by the participation of mantle-derived materials.Combined with previous studies,(Y+Nb)-Rb diagram and Rb/30-Hf-Ta*3 diagram,it can be seen that the diorite in Gemalong area was formed in the post-collisional extensional environment formed in the Early Devonian East Kunlun orogenic belt.
DioriteZircon U-Pb datingWhole rock geochemical analysisPost-collisional extensionGemalong areaEast Kunlun metallogenic belt
万方数据
维普
