Isotope geochemistry and Re–Os geochronology of the Yanjiagou Mo deposit in the central North China Craton

Abstract

The Yanjiagou deposit, located in the central North China Craton (NCC), is a newly found porphyry-type Mo deposit. The Mo mineralization here is spatially associated with the Mapeng batholith. In this study, we identify four stages of ore formation in this deposit: pyrite phyllic stage (I), quartz-pyrite stage (II), quartz-pyrite-molybdenite stage (III), which is the main mineralization stage, and quartz-carbonate stage (IV). We present sulphur and lead isotope data on pyrite, and rhenium and osmium isotopes of molybdenite from the porphyry deposit and evaluate the timing and origin of ore formation. The δ 34 S values of the pyrite range from -1.1‰ to À0.6‰, with an average of À0.875‰, suggesting origin from a mixture of magmatic/mantle sources and the basement rocks. 187 Os = 0.0032 ± 0.0012 ppb) is computed, which reveals a close link between the Mo mineralization and the magmatism that generated the Mapeng batholith. The age is close to the zircon U-Pb age of ca. 130 Ma from the batholith reported in a recent study. The age is also consistent with the timing of mineralization in the Fuping ore cluster in the central NCC, as well as the peak time of lithosphere thinning and destruction of the NCC. We evaluate the spatio-temporal distribution of the Mo deposits in the NCC and identify three important molybdenum provinces along the northern and southern margins of the craton formed during three distinct episodes: Middle to Late Triassic (240-220 Ma), Early Jurassic , and Late Jurassic to Early Cretaceous (150-125 Ma). The third period is considered to mark the most important metallogenic event, coinciding with the peak of lithosphere thinning and craton destruction in the NCC.

Origin and Evolution of the Ore-Forming Fluids in the Liyuan Gold Deposit, Central North China Craton: Constraints from Fluid Inclusions and H-O-C Isotopic Compositions

“…The folds which were formed primarily during Mesoarchean to Paleoproterozoic are coeval with the NNE-trending faults carrying the late Paleoproterozoic mafic-ultramafic dikes [48,49], while the regional NNE-trending faults, which cut across the Precambrian basement and Paleozoic strata, are mainly associated with the Mesozoic (Yanshanian) tectonic events [50,51]. Numerous Au, Ag, Cu, Mo, Pb, and Zn ore deposits, including the Liyuan gold deposit discussed in this paper, and the Lianbaling Pb-Zn, Mujicun Cu-Mo, Dawan Cu-Mo, and Shihu Au deposits, are distributed along the regional NNEtrending faults [52,53] (Figure 1(c)).…”