Sedimentary Processes of the Dazhuyuan Formation in Northern Guizhou (Southwest China): Evidence from Detrital Zircon Geochronology and Whole Rock Geochemistry

The Dazhuyuan Formation (northern Guizhou) is the host stratum for bauxite deposits and enriched with critical metals like Li. We investigated sedimentary processes of the formation using detrital zircon geochronology and whole-rock geochemistry. From bottom to top, the formation comprises iron-rich claystone (IC), clastic bauxite (CB), massive bauxite (MB; where Li is enriched (1555–4210 ppm)), and clastic claystone (CC). From lower part to upper part of the formation, the sedimentary environment becomes more reducing, transitioning from continental to marine–continental facies. The P1d exhibit rare-earth-element (REE) distributions similar to the Hanjiadian Formation. The Hanjiadian Formation detrital-zircon U–Pb ages reach ~960 and ~760 Ma; the IC and CB layers show similar results. The dominant peak of detrital-zircon ages for the MB and CC layers occurs at ~960 Ma, while the ~760-Ma dominant peak disappears. Numerous zircons are aged 1030–1150 Ma, which substantially diverges from the Hanjiadian Formation. All layers exhibit different REE distributions and detrital-zircon age distributions than the Huanglong Formation, indicating that the formation is the primary source for the Dazhuyuan Formation. The MB and CC layers receive contributions from other sources.