Garnet and titanite U–Pb dating of the Kaladawan Fe–Mo orefield in the Altyn Mountains, NW China: Constrains for ore genesis

Abstract The Kaladawan Fe–Mo orefield is located in the east of the Altyn Mountains, NW China. It contains six Fe(–Mo) deposits, with total reserves of 60 Mt Fe and 10 kt Mo by-product. Mineralization is hosted in the contact zone between Early Paleozoic volcanic–sedimentary rocks and Ordovician granite, with intense and pervasive skarn alteration. Skarns exhibit some stratabound features. These deposits were variably classified as sedimentary-type with hydrothermal overprints, submarine volcanogenic iron-oxide- (SVIO-) type or skarn-type, centered on whether they are syngenetic or epigenetic. Titanite and garnet from skarn in the ore field are newly U–Pb dated to be ca. 482.6–481.0 Ma, consistent with the intrusive age of the granite but later than the formation age of the host rocks. These age data also further support that mineralization in the Kaladawan orefield is skarn-type.