The mineralogical and geochemical compositions of the Yaojia Formation sandstones in Qianjiadian area, Songliao Basin are intimately related to their provenance and depositional tectonic setting. Petrographical observation assorting with mineral chemical analysis indicates that the studied rocks have a major clastic mineral association of quartz+cuttings+feldspar with minor pyrite+charcoal shavings+heavy minerals and other transparent minerals. These rocks are also characterized generally by high content of SiO2 （68.4%～79.61%）, relatively high ratio of K2O/Na2O （1.83～2.03） and low concentration of Fe2O3T+MgO （1.48%～4.22%）. The REE patterns are characterized by LREE enrichment, flat HREE, and poor negative Eu and Ce anomalies. The pre-metasomatized CIA （57～63） and PIA （60～71） values, respectively, in connection with the A-CN-K and the AK-C-N modeling commonly suggest that these sediments were derived from source rocks with low-moderate weathering. And Zr/Sc and Th/Sc ratios illustrate that all sediments have undergone moderate degree of weathering and no significant sediment recycling, which indicates proximal provenances and poor sorting. Various diagrams for sedimentary provenance using major and trace elements show all the sediments studied were derived predominantly from felsic magmatic rocks source. Geochemical data for these rocks suggest a passive continental margin tectonic setting.
Shan Zhibo. Detrital modal, geochemical characteristics and tectonic setting of the Yaojia Formation ore-bearing sandstones in Qianjiadian area, Songliao Basin[J]. Chinese Journal of Geology, 2019, 54(2): 472-490.