The Xiaoqinling gold field, located along the southern margin of the North China craton, is the second largest gold producer in China, which comprises more than 1,200 auriferous quartz veins with a proven gold reserve of at least 800 tons. Previously, the absolute age of the gold metallogenesis in this area has not been well defined due to the lack of suitable dating minerals. This study presents new in situ laser ablation-inductively coupled plasma-mass spectrometry U-Pb ages of coexisting hydrothermal monazite and rutile for the Fancha gold deposit in this area, which yielded 206Pb/238U ages of 127.5 ± 0.7 Ma (n = 65, mean square of weighted deviates [MSWD] = 1.8) and 129.7 ± 4.3 Ma (n = 37, MSWD = 1.4), respectively. Both ages overlap within analytical uncertainty at the 2σ level of significance, suggesting that both gold-bearing veins were emplaced at ca. 128 Ma. Mineralogical observations indicate that the monazite and rutile precipitated simultaneously with gold from the hydrothermal fluid. Our new data, combined with recently published monazite age, define a more precise gold episode, demonstrating that the gold endowment of the Xiaoqinling area was formed during a relatively brief period at ca. 130 to 127 Ma. We suggest that auriferous fluids were generated as a result of interactions between the enriched mantle and the lower crust, which was driven by westward flat slab subduction of the Paleo-Pacific plate during the late Mesozoic. The peak of lithospheric thinning during the postsubduction may have led to the rapid release of gold from the fertilized mantle. Consequently, the large number of gold-bearing veins in the Xiaoqinling area may ultimately be related to the tectonic evolution and mantle fluid processes that occurred during Early Cretaceous lithospheric extension.

The Xiaoqinling Precambrian metamorphic terrane is located in the southern margin of the North China Craton, where it is the second largest gold‐producing province in China. The Huashan, Wenyu, and Niangniangshan granitic plutons are distributed from west to east across the Xiaoqinling terrane. To fully reveal the terrane's cooling and uplift history, a systematic thermochronological study of the Niangniangshan pluton was carried out in this work. Combined with previous data for the other two plutons, our new data allow us to draw four important conclusions: (a) The Niangniangshan granitic pluton has experienced three cooling–uplift stages, with a rapid stage from 141.7 to 118.5 Ma, a second slow stage from 118.5 to 40.3 Ma, and a final relatively rapid stage from 40.3 to 29.0 Ma. Correspondingly, the cooling rates are 17.24°C/Ma, 0.77°C/Ma, and 11.50°C/Ma. (b) The three plutons experienced similar post‐emplacement rapid cooling stages until ca. 120 Ma, with high cooling rates of about 17–20°C/Ma. Subsequently, their host terrane entered a long period of tectonic quiescence with cooling rates of less than 1°C/Ma. A new diachronous rapid cooling stage began first in the west at 57 Ma, then in the centre at 45 Ma, and finally in the east at 40 Ma with markedly different cooling rates. In this latter rapid stage, the Huashan and Wenyu plutons experienced a much more rapid cooling and uplift than the Niangniangshan pluton, resulting in the higher elevations and larger outcrop area of granitoids in the west and centre of the terrane than in the east. Consequently, the present topography of the Xiaoqinling terrane was close to present‐day form by the Eocene–Oligocene. (c) The emplacement of the three plutons was prior to the regional extension and detachment faulting in the Xiaoqinling terrane, with the evolution of magmatic thermal domes triggering development of the Xiaoqinling metamorphic core complex. (d) Gold mineralization of the Xiaoqinling goldfield took place at ca. 132–125 Ma, which was coeval with the early rapid cooling stage of the plutons and the extensional detachment faulting of the Xiaoqinling metamorphic core complex. Regionally, the gold mineralization overlaps lithospheric thinning and asthenospheric upwelling below the entire eastern part of the North China Craton that occurred during the major extensional regime in the late Early Cretaceous.

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