Emplacement depth and uplift-erosion of the Guidong complex in northern Guangdong: Implications for deep prospecting in the Xiazhuang uranium ore field

Abstract

The Xiazhuang uranium ore field, situated on the southeastern side of the Guidong complex in northern Guangdong Province, is an important hard rock uranium resource bases in southern China. In this study, petrography, mineral thermobarometry, and apatite fission track (AFT) methods were used to study the genetic mineralogy and uplift-erosion history of various granites in the mining area. The Donggualing body is characterized by high temperature and pressure, medium to high oxygen fugacity, high water content, and alkalinity, with characteristics typical of a subduction zone supply. The biotite chemistry indicates that the Indosinian bodies have high Mg, low temperature, low oxygen fugacity, and peraluminous characteristics, whereas the Yanshanian bodies are calc-alkaline peraluminous granites of crustal origin. Estimates of emplacement depth suggest that biotite barometry may be more reliable than hornblende barometry, with the Caledonian Donggualing body emplaced at a depth of 11.9 km; the Indosinian Xiazhuang, Luxi, and Shituling bodies at an average depth of 14.5 km; and the Yanshanian Taoshuba, Shishitou, and Zhutongjian bodies at an average depth of 6.8 km. AFT and thermal history modeling showed that the uplift of the Indosinian bodies began earlier than that of the Yanshanian bodies, indicating that the Mesozoic-Cenozoic uplift process in the Guidong area expanded from east to west. Based on the physicochemical conditions of diagenesis, AFT thermal history modeling, and previous studies on diagenesis, mineralization ages, fluid inclusions, and deposits, the high U, rich F, low oxygen fugacity, and peraluminous characteristics of the Indosinian bodies are shown to have significantly controlled U enrichment. The natural absence or severe erosion of Indosinian bodies on the western side of the Guidong complex severely affects the spatial distribution of regional deposits. Furthermore, the combined control of the Huangpi and Mashishanshan faults is a key factor in the preservation of orebodies in the Xiazhuang uranium ore field. The deeper part of this area has better potential for mineral exploration than the western part of the Guidong complex.