Recognition of the latest Permian to Early Triassic Cu–Mo mineralization on the northern margin of the North China block and its geological significance

Abstract

In this paper, we present newly obtained molybdenite Re–Os ages for the Chehugou copper–molybdenum deposit and the Yuanbaoshan molybdenum mineral locality from the Chifeng area on the northern margin of the North China block, combined with U–Pb zircon ages of the host granites. The Re–Os isochron age of six molybdenite samples from the Chehugou deposit is 257.5 ± 2.5 Ma and one molybdenite sample from the Yuanbaoshan locality yields a Re–Os model age of 248.0 ± 2.7 Ma. These ages clearly indicate the signature latest Permian to Early Triassic Cu–Mo or Mo mineralization that has not been previously recognized. Zircon LA-ICP-MS U–Pb dating shows that the host granites of the Chehugou deposit and Yuanbaoshan locality formed in the Late Devonian (376 ± 3 Ma) and Late Permian (269 ± 3 Ma), respectively, and is not of Jurassic age, as previously thought. The latest Permian to Early Triassic Cu–Mo mineralization is likely related to extension due to final closure of the Paleo-Asian Ocean and amalgamation of the Mongolian arc terranes with the northern North China block. The establishment of a latest Permian to Early Triassic age for mineralization should encourage renewed exploration aimed at the discovery of new Mo or Cu–Mo resources along the northern margin of the North China block.