Geochemistry of the diamondiferous olivine basalt and magmatic evolution in the Bailushan area, Xuzhou

Xuzhou is located in the southeast of the north China craton. Alkaline ultrabasic rocks-basic rocks are widely developed in and around it, where there are some diamondiferous rocks, but mainly kimberlite. During the prospecting of primary diamond deposit, the diamondiferous rocks were discovered in Bailushan, north of Xuzhou. The SiO₂ content of olive basalt ranges from 42.64% to 51.13%, K₂O+Na₂O from 2.57% to 5.93%, Al₂O₃ from 10.48% to 13.53%, and MgO content from 3.11% to 19.34%. On the TAS diagram, the points of basic rocks in this area all fall into the range of basalt, indicating high potassium calcium alkalinity. Trace element signatures indicate that samples from Bailushan are close to the OIB and volcanic arc regions. The higher Ba/Th ratio of enriched endmember suggests that the basalts contain lower continental crust materials. Therefore, the wide range of elements geochemistry and isotopic composition of olivine basalts is not mainly caused by crustal contamination, but because the source area contains residual recirculation subcontinental crust. These geochemical characteristics suggest that the Bailushan olivine basalt in Xuzhou is related to the kimberlite in Liaoning and Shandong, which provides a favorable clue for diamond prospecting in this area.