The endogenetic metallogeny of northern Laos and its relation to the intermediate-felsic magmatism at different stages of the Paleotethyan tectonics: a review and synthesis

Northern Laos is at the junction of the Paleo-Tethys convergence and assemblages of several crustal blocks such as the Sibumasu, South China and the Indochina blocks, and also comprises the Houayxay-Sukhothai, the Simao-Phongsaly, the Louang Phrabang-Loei, the Truong Son and the Song Da terranes. During the amalgamation of the terranes derived from Gondwana, calc-alkaline magmatic rocks, peraluminous magmatic rocks, sub-alkaline volcanic-intrusive complexes, and alkaline rocks and related endogenetic metallogenic systems were emplaced in multiple stages during subduction-collision and post-collision events. According to chronological order, the tectonic-magmatic development processes and the metallogenic assemblages can be divided as follows: (1) Subduction arc related magmatic hydrothermal metallogenic systems, formed in calc-alkaline magmatic rocks due to the initial subduction during the late Carboniferous including porphyry Cu-Au deposits, skarn and epithermal Cu-Au deposits; (2) Arc-continent collisions and back-arc extensional settings and associated magmatic hydrothermal mineralization with calc-alkaline porphyry Cu-Au deposits, as well as alkaline porphyry and epithermal Cu-Au deposits during the early Permian; (3) Collisional orogenic magmatic hydrothermal metallogenic systems formed in the late Permian to the early to middle Triassic comprising high alumina magmatic rocks with Au-Pb-Zn(Ag)-Fe-Cu deposits associated with both orogenic type and hydrothermal vein type, and; (4) Post-orogenic extensional tectonic-hydrothermal metallogenic assemblages, which were formed in calc-alkaline to alkaline rocks within a exten 1000 sional tectonic setting during the late Triassic-early Jurassic, including: porphyry Cu-Mo-Sn deposits, porphyry-skarn and epithermal Cu-Au deposits, and also subalkaline volcanic-intrusive complex-related hydrothermal stratabound Cu-Pb-Zn and Au-Sb-Hg deposits. Further detailed studies and classification of metallogenic assemblages in Laos is of significance to understand the nature and timing of different mineralization styles in relation the evolution of the Paleo-Tethys.