Detrital Zircon U-Pb Geochronology of the Dazhuyuan Formation in Northern Guizhou: Implications for Bauxite Mineralization

The Late Carboniferous Dazhuyuan Formation, an important bauxite bearing bed, lies along the Northern Guizhou-Southern Chongqing formation. For tracing the material source of the bauxite, U-Pb dates on detrital zircon of aluminous from Dazhuyuan bauxite deposit using Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICPMS) have been determined. The results show that 84 groups of concordant age are distributed over a wide range, varying from 447 to 2825 Ma, with the main populations ranging from 505-660 Ma (n=5), 714-794 Ma (n=13), 900-1302 Ma (n=42) and 2473-2500 Ma (n=5). Compared with the detrital zircon age spectrum of Paleozoic Clastic of South China, the result lacks the data from about 440-400 Ma, which belongs to the middle-upper Devonian, more similar to a detrital zircon age spectrum of the Ordovician-Lower Devonian. Combined with the regional geological characteristics, it is postulated that (1) the detrital zircons of the aluminous come from the Hanjiadian group (S₁hj), which is the important metallogenic parent rocks of the bauxite. (2) The Caledonian orogeny made the collision between the Cathaysian block and the Yangtze block, implying that the Cathaysia block uplifted rapidly and suffered from erosion in the Silurian, which made a foundation providing a large amount of metallogenic material for the formation of the bauxite.