# Provenance and Paleo-Environment of the Late Carboniferous Bauxite Formations in Southern Shanxi
## 1 Introduction  
Based on the lithology of the underlying bedrock and metallogenic characteristics of bauxite, bauxite deposits are categorized into lateritic, karst, and sedimentary types [1]. In China, sedimentary bauxite is the most prevalent, comprising over 80% of the country's total bauxite reserves. These deposits are extensively found in Shanxi, Henan, Guizhou, Guangxi, and other regions of China. Bauxite has wide-ranging industrial applications and is classified as a strategic critical mineral by the United States, European Union, Japan, and China [2]. During the Late Carboniferous, the bauxite in the North China Craton (NCC) was relatively uniform, primarily concentrated at the base of the Benxi Formation. They conform to the coal-bearing strata of the Taiyuan Formation from the Late Carboniferous and parallel unconformity with the underlying Ordovician Majiagou or Fengfeng Formation [3]. Recently, numerous studies have been conducted on North China bauxite in terms of mineralogy, geochemistry, metallogenic materials source, ore deposit genesis, and metallogenicage [4; 5; 6; 7; 8; 9; 10; 11; 12]. The researchs show that differences exist in the sedimentary sources of bauxite in the northern, central, and southern regions of the NCC. The substantial clastic material present in the southern to central parts of the NCC is derived from the uplifted North Qinling orogenic belt [6; 13], while in the northern part of the NCC, the materials originate from the uplift zone caused by the southern branch of the Central Asian Orogenic Belt (Bainaimiao continental arc) [14; 12]. The detrital zircon age spectra in the bauxite deposits of the central part of the NCC demonstrate characteristics of both southern and northern sources [10]. However, the absence of any evidence pertaining to fluvial deposits has been observed in the bauxite beds thus far, suggesting that the convergence mechanism of the southern and northern sources in the central and southern parts of the NCC is still unclear, and the source of materials remaining a matter of debate. Shanxi Province is a major bauxite-producing region in China, with the large bauxite resource reserves in the country. These resources are distributed across the province and can be categorized into seven primary bauxite concentration areas from south to north and east to west: Pinglu, Wuxiang, Qinyuan, Linxian-Jiaokou, Yangquan, Yuanping-Ningwu, and Baode-Xingxian [15; 16]. According to the mineralization environment, bauxite can be classified into three types around the Pinglu mine area: marine, terrestrial, and marine-terrestrial transitional facies. Some geologists think it may be occurred in a weakly oxidizing environment of marine or marine-terrestrial transitional facies [17], coastal lake facies [15], marine sedimentary [18], or surface alkaline-reducing karst depression environments with microorganisms widely participating in the mineralization process [19]. And there are mainly three theories regarding the material sources of karst-type bauxite deposits in Shanxi Province. [PERSON] [20], [PERSON] et al. [21], and [PERSON] et al. [22] suggested that the bauxite originated from ancient landmass aluminosilicate rocks. [PERSON] [23] and [PERSON] et al. [24] hold that the bauxite is a mixed source from both the basement carbonate rocks and ancient landmass aluminosilicate rocks. However, [PERSON] et al. [19] thinks that the main body of the iron-rich clay rocks at the bottom of large karst-type bauxite deposits was formed by in situ weathering of the underlying carbonate rocks, while the upper bauxite and clay rocks are of allochthonous origin. In the geological history, the area of Pinglu County has experienced the ancient rock metamorphism and tectonic movement, forming a unique geological structural characteristics and rich mineral resources. Although some scholars have conducted research on the sedimentary bauxite in the Pingguo mining area, the number of samples is too small, and the testing data is limited.