Zhang, and 5 co-authors, reported in 2006 that the No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit. REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this deposit have been systematically studied in this paper. The authors showed that the alkali-metasomatic granites and other altered rocks have the same REE distribution patterns as Indosinian granites.
The authors also found that the hydrothermal ore-forming solution had altered the Indosinian granites, and ore-forming materials may directly originate from the Indosinian granites. Calcite and fluorite of different stages are the products derived from the same source but different stages. The evolution and degassing of the mineralizing solution might induce LREE enrichment to varying degree. Mantle fluid and a large volume of mineralizer may be the crucial factors controlling uranium mineralization, and the hydrothermal solution with mineralizer played an important role in U transport and concentration. Meanwhile, the degassing of CO2 might promote U and REE precipitation.
The authors concluded that:
1) Ore-forming materials were derived mainly from the Indosinian granites. The Yanshanian granites may induce mineralization to carry on and provide a small part of ore-forming materials.
2) From the early-ore stage to the late-ore stage Eu showed a tendency of strong depletion to moderately strong depletion, indicating that the mineralization environment had turned into a relatively oxidizing one; U-mineralizing solutions tend to become relatively enriched in LREE to relatively enriched in HREE, the alkalinity of U-mineralization solutions was reduced during mineralization.
3) Calcites and fluorites of the different stages are the products derived from the same source but different stages of hydrothermal fluid. The evolution and degassing of mineralizing solutions might induce LREE enrichment to various degrees and this may be the reason why calcites show different REE distribution patterns between common hydrothermal ore deposits and the deposit studied, and
(4) Mantle fluids possibly provided a large volume of mineralizer (CO2) and part of early ore-forming fluid for the formation of the No.302 uranium deposit.
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