Origin and Role of Kaolinization in Roll-Front Uranium Deposits and Its Response to Ore-Forming Fluids in the Yili Basin, China

Table 1

Altered minerals and geochemical indexes of each geochemical zone in the Mengqiguer uranium deposit.

Altered minerals and geochemical indexes	Oxidation zone		Transition zone (mineralized zone)	Primary zone
	Strong oxidation zone	Weak oxidation zone
Colors	Red, light-red	Yellow, yellowish-white	Gray, grayish-white	Gray, dark-gray
Fe-minerals	Hematite, limonite	Limonite, rare pyrite	Pyrite, goethite	Pyrite, magnetite and siderite
Alterations	Hematitization, limonitization, kaolinization		Kaolinization, silicification, and uranium mineralization	Carbonation and chlorite
U-content (ppm)	4.0–6.0	6.5–20.6	>100	6.0–10.0
Total organic carbon (TOC) (wt%)	0.05–0.07	0.08–0.10	>0.5	>0.20
Fe^3+/Fe^2+	>0.9	0.5–0.8	0.3–0.5	0.2–0.4