Publication Type:Book Chapter
Source:34th international geological congress; abstracts, [International Geological Congress], [location varies], International, Volume 34, p.2655 (2012)
Keywords:absolute age, amphibolites, Asia, chemical composition, China, complexes, dates, Devonian, diagenesis, Far East, gabbros, Hydrothermal alteration, igneous rocks, Inner Mongolia China, ion probe data, iridium, Lower Devonian, magmatism, mass spectra, metal ores, metals, Metamorphic rocks, metasomatism, mineral composition, mineral deposits, genesis, nesosilicates, NICKEL, ore-forming fluids, orthosilicates, osmium, Paleozoic, palladium ores, platinum group, platinum ores, plutonic rocks, pyroxenite, Rhodium, ruthenium, SHRIMP data, silicates, spectra, sulfur, syngenesis, Temperature, U/Pb, ultramafics, websterite, zircon, zircon group
The Wengeqi complex in Guyang County, Inner Mongolia, is one of several Pd-Pt-mineralized Paleozoic mafic-ultramafic complexes along the north-central margin of the North China craton. The complex comprises pyroxenites, biotite pyroxenites, amphibole pyroxenites, gabbros, and amphibolites. Zircons extracted from a pyroxenite yield a U-Pb SHRIMP age of 399+ or -4 Ma. Several 2-6-m wide syngenetic websterite dikes contain 1-3 ppm Pd+Pd and are dominated by pyrite-chalcopyrite-pyrrhotite-magnetite-(pentlandite) assemblages with minor sperrylite, sudburyite, and kotuskite. Textural relationships indicate that pyrite has replaced magmatic chalcopyrite and that R magnetite has replaced magmatic pyrrhotite. The mineralization is enriched in Pd-Pt-Cu > Au >> Rh-Ir-Os-Ni > Ru, similar to other occurrences of hydrothermally modified magmatic mineralization, but very different from the much less fractionated compositions of magmatic PGE mineralization. Textural, mineralogical, and geochemical relationships are consistent with alteration of an original magmatic Fe-Ni-Cu sulfide assemblage by a S-rich oxidizing high-temperature (deuteric) hydrothermal fluid.
GeoRef, Copyright 2018, American Geological Institute.<br/>2013-051524<br/>Guyang China<br/>Wengeqi Complex