Comparison On Geochemical Characteristics Of Ore-forming Magmatic Rocks In Baoyintu Porphyry Molybdenum Mine And Chilean Porphyry Coppermolybdenum Belt

Baoyintu is a large molybdenum deposit newly discovered in Yanshanmagmatic belt which is on the northern margin of North China ancient continent. Itis located in the Zongnai-Shala mountain tectonic zone which is on the northernmargin of the North China plate and the west side of Langshan rift valley. Baoyintuis sandwiched between two NE-trending regional faults-Alashan and Engel Usu fault.Chilean porphyry copper （molybdenum） deposits are mainly located in the junctionof Nazca plate and the South American continental plate and nearly north-southzonal distribution along the plate binding lines. El Teniente and Escondida areselected to compare with Baoyintu in this paper.Geochemical characteristics show that Baoyintu ore-forming granites’ SiO2content is relatively high, with an average of more than70%, characteristicparameter A/CNK＞1, mainly belonging to high-K calc-alkaline series; low contentof Sr, Sr/Ba <1, high Rb/Sr ratios, low Th/U ratios, with unobvious light and heavyrare earth element fractionation and obvious negative Eu anomalies, belonging tothe continental crust remelting granites. Teniente and Escondida ore-formingporphyries’ SiO₂are low, respectively average of63.49%and58.22%, characteristicparameter A/CNK＜1, mainly belonging to calc-alkaline series; high Sr content,Sr/Ba＞1, low Rb/Sr ratios, high Th/U ratios, with obvious light and heavy rareearth element fractionation and unobvious Eu anomalies, belonging to the oceaniccrust remelting crust-mantle mixing magmatic rocks.Baoyintu’s ore-forming porphyries are isolated intrusions, which aresurrounded by Lower Proterozoic metamorphic rocks. ore-forming porphyries andwall rocks in Teniente and Escondida have the same source magmas. The volcanicserupted earlier act as wall rocks of ore-forming magmas which intrude later.According to the related definition of ore deposits, Baoyintu is epigenetic porphyrydeposit and Teniente and Escondida syngenetic porphyry deposits.