Whole-rock geochemistry and geochronology of meta-basic rocks from the cobalt exploration area in Kuandian,eastern Liaoning Province
In this study,the whole-rock geochemistry and zircon U-Pb ages are reported for the meta-basic rocks of the Li'eryu Formation of the South Liaohe Group from the cobalt exploration area in Kuandian.These data provide a significant insight into the tectonic background,as well as the source of cobalt.Geochemical features of the meta-basic rocks in boreholes show that they are orthorhombic amphibolite,and have similar rare-earth elements(REEs)patterns,with slightly negative Eu anomalies.REEs and trace elements compositions have affinity to those of E-MORB.Based on the mineral compositional analyses and p-t estimates using conventional geothermobarometers,the clinopyroxene-bearing amphibolite(ZK2-1)records p-t conditions of p=0.82～1.00 GPa and t=712～751℃,which probably constrained the peak high amphibolites-facies stage.The metamorphic p-t conditions of(clinopyrox-ene-bearing)amphibolite(ZK1-1 and ZK3-1)are p=0.42～0.81 GPa,t=688～759℃ and p=0.59～0.85 GPa,t=703～739℃,respectively,which represent the conditions of the retrograde stage.The metamorphic zircon from the meta-basic rocks yield the SHRIMP U-Pb ages of 1 857～1 850 Ma.The integrated study of geochemistry and zircon U-Pb dating reveals that their protoliths of the meta-basic rocks are mid-Paleoproterozoic tholeiitic basalt and formed in an extended tectonic environment.Their protoliths underwent significant crustal assimilation imply that the scale of the mid-Paleoproterozoic oceanic basin may be limited.By comparing the geochemical characteristics of meta-basic rocks in the North and South Liaohe groups,it is believed that meta-basic rocks in the Kuandian area are not the main source of cobalt mineralization.The material sources of cobalt mineralization still needs further research.
万方数据
维普
