Xiao-Qing Zhu

Metallogenic Model of Bauxite in Central Guizhou Province: an Example of Lindai Deposit

The bauxites in central Guizhou are hosted by the Lower Carboniferous Jiujialu Formation. Geochemistrial characteristics of the Lindai bauxite deposit indicate that the underlying Shilengshui Formation dolomite is the precursor rock of mineral resources. Weathering simulation experiments show that Si is most likely to migrate with groundwater, the migration rate of which is several magnitude higher than Al and Fe under nature conditions (pH=3–9). The neutral and acid non-reducing condition is the most conducive to the Al rich and Si removal, while the acid reducing conditions is the most conducive to the Al rich and Fe removal. In the process of bauxite formation, coal beds overlying the Al-bearing rock series or other rock formation rich in organic materials can produce acid reducing groundwater, which are important for the bauxite formation. Finally, propose the metallogenic model of the bauxite in central Guizhou Province and put forward three new words which are “original bauxite material”, “bauxite material” and “original bauxite”.

Early Paleoproterozoic Metallogenic Explosion in North China Craton

This chapter compiles the geology and geochronology of numerous ores, including graphite, phosphorite, the Lake Superior type BIFs, marble, boron, magnesite, and lead-zinc deposits, hosted in 2.5–1.8 Ga stata from the North China Craton (NCC) and elsewhere, and thereby provides insights into understanding the mineralization of the early Paleoproterozoic metallogenic explosion in NCC. These mineralized records, accompanied with the blooms of biological photosynthesis (indicated by graphite, phosphorite deposits, organics in black shale), suggested different mineralizations, which responded to different stages of dramatic Earth’s environmental changes characteristic of the Great Oxidation Event (GOE). These changes includes that the early-stage hydrosphere oxidation (2.5–2.3 Ga), indicated by numerous development of the Lake Superior type BIFs; through the turnpoint from hydrosphere to atmosphere oxidation (2.3–2.25 Ga), indicated by the 2.29–2.25 Ga Huronnian Glaciation Event (HGE) and devoid of Rand-type Au–U deposits, to the late-stage atmospheric oxygenation, followed by 2.25–1.8 Ga sediments of thick-bedded carbonates strata and related deposits (e.g., marble, magnesite, boron, and lead-zinc deposits), the 2.25–1.95 Ga red beds, 2.22–2.06 Ga δ13Ccarb positive excursion (Lomagundi/Jatulian Event), as well as the prevail of black shales at 2.0–1.7 Ga and disappear of BIFs at ca. 1.8 Ga.