Comparison of the ultrabasic rocks associated with Cu-Ni deposits in Beishan and Jinchuan, Gansu Province and those associated with within-plate environment: preliminary results of big data research

Abstract

In this study, we collected data on the ultrabasic rocks related to Cu-Ni ore in Beishan and Jinchuan, Gansu Province and compared with that of the global intra-plate ultrabasic (WPU) rock collection in the GEOROC and PetDB databases. We found that in Beishan and Jinchuan ultrabasic rocks, the average elemental contents related to Cu-Ni were close to that of WPU (except for the slightly enriched LILE). Therefore, elements Cu, Cs, Nb and Ta or elemental pairs Rb/Nb, CaO in ultrabasic rocks can be used as important geochemical prospecting indicators for the Beishan and Jinchuan ultrabasic ore deposits. Beishan is distinguished from Jinchuan by high Th/Nb ratio and HREE enrichment. Our Pearson correlation coefficient study further indicated that the two ultrabasic rocks have different distribution, formation age and source area characteristics but are highly correlated geochemically, whereas for total WPU (WPU T ) or WPU of similar coordinates the correlation is relatively poor. However, despite extremely low geochemical similarity for WPU T , the average geochemical characteristics of WPU is similar to the Beishan and Jinchuan ultrabasic rocks. Meanwhile, we examined the data of 26 basic-ultrabasic rocks related to Cu-Ni sulfide deposits in the areas of Baishiquan, Shixi, Hulu, east of Huangshan, etc., and compare them with that of basic-ultrabasic rocks associated with the Beishan and Jinchuan Cu-Ni sulfide deposits in Gansu. We found still an extremely high overall correlation. Therefore, we conclude that the ultrabasic rocks associated with Cu-Ni sulfide deposits share some geochemical similarities provided with modifications by other effects during the formation processes. © 2019, Editorial Office of Earth Science Frontiers. All right reserved.