Geochemical Characteristics and Genesis of Late Cretaceous to Paleogene Basalts in the Tuyon Basin, South Tianshan Mountains

The Tianshan Mountains is believed to be a typical intercontinental mountain belt, which is formed during the tectonic amalgamation of the Tarim and Tianshan blocks and the Siberian carton in Late Carboniferous-Permian period. A series of basaltic extrusive and intrusive units emplaced primarily into the Late Cretaceous-Paleogene sedimentary rocks in the Tuyon basin and its adjacent area, the South Tianshan Mountains. Geochemical data of the basalts show low Sr and Pb isotopic values and relative high Nd values (87Sr/86Sr = 0.703554 ~ 0.703884; 143Nd/144Nd = 0.512838 ~ 0.512904; 206Pb/204Pb = 18.0063 ~ 18.4720; 207Pb/204Pb = 15.5060; 208Pb/204P b= 37.8072 ~ 37.9290). The data of major elements, trace elements and rare earth elements of the basalts indicate that these basaltic rocks are similar to those beneath the Hawaiian Islands. In the Tuyon basin and its adjacent areas, some Cenozoic alkaline basaltic magmatism may be related to the Cenozoic activity of mantle plume