Geological characteristics of paleokarst type gold deposits in western Guangxi

Abstract：From the Cambrian to Triassic several erosions took place in western Guangxi. It has been largely ascertained that paleokarst surfaces formed during 11 sedimentary hiatuses in the area. Subaqueous karstification that continued for a relatively long period of time during two extensive tectonic uplifts and one rift extension resulted in strong corrosion of mainly Paleozoic carbonate rock series and formation of extensive paleokarst surface. These paleokarst surfaces exerted very pronounced controlling effects on finely disseminated gold deposits. Part of gold deposits do not directly occur on the paleokarst surfaces, but the ore-controlling faults are mostly related to the hidden paleokarst zones at depths. The paleokarst surfaces have played an indirect role in controlling mineralization. The main mineralized rocks include fine clastic rocks, siliceous rocks and basic and intermediate-acid intrusive and extrusive rocks, which are all sialic rocks; whereas the ultimate footwall rocks of the mineralization are all carbonate rocks below the paleokarst surfaces. The mechanism of gold deposit formation is as follows: when tectonism and metamorphism repeatedly occurred on the buried paleokarst hills, gold leached from the strata was concentrated on the paleokarst erosional surfaces or their influence belts and thus the ore formed.