Burial and Exhumation History of the Lujing Uranium Ore Field, Zhuguangshan Complex, South China: Evidence from Low-Temperature Thermochronology

Abstract

The Zhuguangshan complex hosts the main uranium production area in South China. We report (U-Th)/He and fission track thermochronological data from Triassic–Jurassic mineralized and non-mineralized granites and overlying Cambrian and Cretaceous sandstone units from the Lujing uranium ore field (LUOF) to constrain the upper crustal tectono-thermal evolution of the central Zhuguangshan complex. Two Cambrian sandstones yield reproducible zircon (U-Th)/He (ZHe) ages of 133–106 Ma and low effective uranium (eU) content (270–776 ppm). One Upper Cretaceous sandstone and seven Mesozoic granites are characterized by significant variability in ZHe ages (154–83 Ma and 167–36 Ma, respectively), which show a negative relationship with eU content (244–1098 ppm and 402–4615 ppm), suggesting that the observed age dispersion can be attributed to the effect of radiation damage accumulation on 4He diffusion. Correspondence between ZHe ages from sandstones and granites indicates that surrounding sedimentary rocks and igneous intrusions supplied sediment to the Cretaceous–Paleogene Fengzhou Basin lying adjacent to the LUOF. The concordance of apatite fission track (AFT) central ages (61–54 Ma) and unimodal distributions of confined track lengths of five samples from different rock units suggest that both sandstone and granite samples experienced a similar cooling history throughout the entire apatite partial annealing zone (~110–60 °C). Apatite (U-Th-Sm)/He (AHe) ages from six non-mineralized samples range from 67 to 19 Ma, with no apparent correlation to eU content (2–78 ppm). Thermal history modeling of data suggests that the LUOF experienced relatively rapid Early Cretaceous cooling. In most samples, this was followed by the latest Early Cretaceous–Late Cretaceous reheating and subsequent latest Late Cretaceous–Recent cooling to surface temperatures. This history is considered as a response to the transmission of far-field stresses, involving alternating periods of regional compression and extension, related to paleo-Pacific plate subduction and subsequent rollback followed by Late Paleogene–Recent India–Asia collision and associated uplift and eastward extrusion of the Tibetan Plateau. Thermal history models are consistent with the Fengzhou Basin having been significantly more extensive in the Late Cretaceous–Early Paleogene, covering much of the LUOF. Uranium ore bodies which may have formed prior to the Late Cretaceous may have been eroded by as much as ~1.2 to 4.8 km during the latest Late Cretaceous–Recent denudation.

Apatite Fission Track Thermochronology of Granite from the Xiazhuang Uranium Ore Field, South China: Implications for Exhumation History and Ore Preservation

“…1) (e.g., Wang et al, 2013Wang F et al, 2015;Zhu et al, 2022;Zhou et al, 2023). The NMB, generally referred to the E-W trending Nanling Range, is geographically located within the central part of the Cathaysia Block (Sun Y et al, 2021b;Bonnetti et al, 2023). In the Meso-Cenozoic, large exposed area of granitoids and their close relation to abundant hydrothermal uranium, tungsten, tin, bismuth and other specialty metal mineral resources were developed in the NMB, which formed under the control of the subduction of the Paleo-Pacific Plate, the Neo-Tethys Ocean and the India-Australia Plate (e.g., Mao et al, 2011Mao et al, , 2014Sun W D et al, 2012;Song et al, 2016;Zhu et al, 2016;Li et al, 2019;Wang D H et al, 2020;Sun Y et al, 2021b;Zhang et al, 2023).…”

A geospatial platform for the tectonic interpretation of low-temperature thermochronology Big Data

“…These observations, in turn, allow scientists to constrain the timing and rate of a breadth of geological processes which can affect the thermal state of the crust over geological time, including the advection of mass and heat due to the growth of mountain belts, extensional basin formation, and long-term denudation 1-4 . Consequently, low-temperature thermochronology is an important tool for studying surface weathering processes 5 , paleoclimate [6][7][8] , and climate change 9,10 , as well as for constraining the formation and preservation of various natural resources, such as hydrocarbons 11,12 , hydrothermal and supergene ore deposits [13][14][15][16] , and geothermal energy fields 17,18 . In certain instances, such analyses can even record thermal events related to localised conductive heat transfer related to igneous activity 19 , volcanic eruptions 20,21 , groundwater advection 22,23 , hydrothermal fluid flow 24 , faulting and shear heating 25,26 , wildfires 27 , or meteorite formation 28 .…”