Mixed volcanogenic–lithogenic sources for Permian bauxite deposits in southwestern Youjiang Basin, South China, and their metallogenic significance

Interaction between karst terrain and bauxites: evidence from Quaternary orebody distribution in Guangxi, SW China

“…The self-organization mechanism means that the various components of the system of interest spontaneously reacted in a purposeful (non-random) manner, such as the resultant regular distribution of element and geomorphology 29 . The interaction between the oxidized, alkaline water in karst terrain and the ferrous clay minerals that released H + during bauxite secondary weathering 7 , 8 , 10 , 15 (Fig. 6a ) was more intensive in high-elevation terrain than low-elevation one.…”

“…The genesis of the Quaternary bauxites is a unique process that involved not only the formation of bauxite but also the renovation of karst topography 12 . Abundant researches on the Quaternary bauxites have been carried out, mainly focusing on mineralogical and geochemical features 8 – 10 , 13 – 16 , mineralogical change and elemental migration during bauxitization or bauxite transformation 11 , 14 , 15 , ore quality and vertical structure 9 . Despite these researches, the distribution and controls of Quaternary bauxites have not yet been studied in detail and especially the relation between karstification process and Quaternary bauxite formation was obviously ignored, although the reaction of bauxites or terra rossa with carbonates has been verified 17 – 21 .…”

“…The western Guangxi paleogeographically belongs to the southwestern quadrant of the Youjiang Basin located along the southwestern margin of the South China block 15 (Fig. 1a ).…”

Provenance of the Lower Triassic Clastic Rocks in the Southwestern Margin of the South China Craton and Its Implications for the Subduction Polarity of the Paleo-Tethyan Ocean

“…Detrital zircons with the main peak at ~260-250 Ma were widely reported in the Late Permian to Early Triassic strata from the southwestern margin of the South China Craton (Figures 1, 12) (Yang et al, 2012(Yang et al, , 2014(Yang et al, , 2015Huang et al, 2014;Yu et al, 2016;Hou et al, 2017;Xu et al, 2019). Zircons from the upper and lower parts of Upper Permian sedimentary rocks in the northern Youjiang Basin are mostly plotted in the within-plate/ anorogenic field (Figure 9) and were derived from the Emeishan volcanic rocks (Yang et al, 2012(Yang et al, , 2014(Yang et al, , 2015Huang et al, 2014;Yu et al, 2016). However, zircons from the top of Upper Permian and Lower Triassic clastic rocks in the northern Youjiang Basin (Yang et al, 2012(Yang et al, , 2014 and Upper Permian sedimentary rocks in the southern Youjiang Basin (Yu et al, 2016) are mostly plotted in the arc-related/orogenic field (Figure 9).…”

“…Magmatic rocks are poorly exposed along the Paleo-Tethyan Ocean between the South China Craton and Indochina Block (Figure 1), and thus its subduction polarity has been controversial. Some studies suggested that the subduction was bidirectional (e.g., Zhong et al, 2013;Hou et al, 2017;Xia et al, 2019;Xu et al, 2019), whereas other studies argued that the subduction was unidirectional (e.g., Faure et al, 2014;Ngo et al, 2016;Yu et al, 2016;Gan et al, 2021;Li et al, 2021;Wang et al, 2021). The latter suggested that the southwestern margin of the South China Craton was a passive continental margin (Yan et al, 2019), and the Paleo-Tethyan Ocean may only undergo a subduction westward beneath the Indochina Block during the Late Permian-Early Triassic (Jian et al, 2009;Faure et al, 2014;Ngo et al, 2016;Li et al, 2021;Wang et al, 2021).…”