Zircon U-Pb age, geochemical characteristics and mineralization, geotectonic significance for anorthosite of the ilmenite field in Tete Province, Mozambique

Mozambique is located in southern Africa. It is rich in mineral resources, and is one of the major export countries of titanium ore. Currently most industrial mining is based on the titanium zirconium sand ore along the coast. The primary ilmenite deposits are far less explored, and their geological background is largely unclear. A series of anorthosite samples closely related to the primary ilmenite have been collected in the Tete Province, Mozambique. Zircon U-Pb ages for the anorthosite samples are 580± 5Ma, which indicate the time of rock formation. The chemical characteristics of the samples indicate that the anorthosites are low Ti, low Mg and low K tholeiites. Rare earth elements show obvious accumulation of plagioclase, δEu shows extremely high positive anomaly; the LREE/HREE ratios are 8.27~21.44, which shows the enrichment of LREE, indicating that the anorthosites were formed by high-degree melting and crystallization differentiation of the primary mantle. The trace elements have obvious enrichment of Sr, Ba and other large-ion lithophile elements, as well as depletion of Zr, Nb and other high field strength elements. The Ta/Hf ratios are 0.1~0.26, Th/Ta ratios are 3.14~13.59, reflecting the formation of anorthosites in the continental retro-arc extensional tectonic environment. The study of the country rock of the ore-forming ilmenite has revealed that the genetic type of the ilmenite is late-stage magmatic crystallization differentiation, and the ore-forming model is crystallization, differentiation, pressure, filtration. Our data also show the important evidence of the 660~610Ma Pan-African orogeny in the Zambezi tectonic zone in Mozambique. © 2021, Science Press. All right reserved.