Zheng Yisu, Duan Jianbing, Lü Yonghua, Huang Qiangfu, Chen Niannan, Li Mangen, Song Zhijie, Guan Baowen, Liao Yuanyuan, Fan Pengfei, Lu Jinping
School of Earth Sciences, East China University of Technology, Nanchang, Jiangxi 330013, China.
National Key Laboratory of Prospecting, Mining and Remote Sense Detecting on Uranium Resources, East China University of Technology, Nanchang, Jiangxi 330013, China.
ACS Omega. 2025 Aug 12;10(33):37201-37217. doi: 10.1021/acsomega.5c01899. eCollection 2025 Aug 26.
The Manglai uranium deposit is located in the Tabei Sag within the Manit Depression, centrally positioned in the eastern Erlian Basin at the core of an ancient valley uranium metallogenic belt. This study analyzed the geochemical properties of 22 clastic and mudstone samples from the Lower Cretaceous Saihan Formation in the Manglai deposit to assess its tectonic setting, provenance direction, redox conditions, and paleoclimatic environment. Key findings reveal that (1) The primary sediment source of the Saihan Formation in the Manglai deposit consists of felsic igneous rocks, situated mainly in a passive continental margin setting. Subunits within the Saihan Formation show enrichment in light rare earth elements (LREEs) and relative depletion in heavy rare earth elements (HREEs), presenting a right-leaning rare earth element distribution pattern with high concentrations of large-ion lithophile elements such as Rb, U, and Sr. (2) Similarities in rare earth and trace element distributions between the Saihan Formation and the northern source region suggest that the sediments were derived from the Chaganaobao and Weijing regions to the north, where parent rocks predominantly consist of Early Cretaceous rhyolite and Permian biotite potassic granite. These origins are linked to late Paleozoic north-south compression between the Siberian and North China Plates, marked by cycles of oceanic crust subduction, continental crust accretion, and block collision, accompanied by recurrent granitoid magmatism involving crustal assimilation and contamination. (3) The Chemical Index of Alteration (CIA) and Index of Compositional Variability (ICV) indicate that the Saihan Formation underwent moderate to intense weathering during deposition with relatively low rock maturity. Coupled with trace element geochemistry, these findings point to an arid to semiarid, mildly saline, and oxygen-rich depositional environment for the Saihan Formation.
芒来铀矿床位于满都凹陷内的塔北洼陷，地处二连盆地东部中心位置，位于一个古河谷铀成矿带的核心部位。本研究分析了芒来矿床下白垩统赛汉组22个碎屑岩和泥岩样品的地球化学性质，以评估其构造背景、物源方向、氧化还原条件和古气候环境。主要研究结果表明：（1）芒来矿床赛汉组的主要沉积物来源为长英质火成岩，主要位于被动大陆边缘环境。赛汉组各亚单元轻稀土元素（LREEs）富集，重稀土元素（HREEs）相对亏损，呈现右倾稀土元素分布模式，且Rb、U、Sr等大离子亲石元素含量较高。（2）赛汉组与北部源区稀土和微量元素分布的相似性表明，沉积物来源于北部的查干敖包和苇井地区，其母岩主要为早白垩世流纹岩和二叠纪黑云母钾长花岗岩。这些物源与晚古生代西伯利亚板块和华北板块之间的南北向挤压作用有关，其特征为洋壳俯冲、陆壳增生和地块碰撞的旋回，并伴有涉及地壳同化和污染的反复花岗岩类岩浆活动。（3）化学蚀变指数（CIA）和成分变异指数（ICV）表明，赛汉组在沉积过程中经历了中等至强烈的风化作用，岩石成熟度相对较低。结合微量元素地球化学，这些研究结果表明赛汉组的沉积环境为干旱至半干旱、轻度盐碱化且富氧环境。
