关键词: 贺兰山, 晚三叠世, 主微量元素, 物源时空演化

Abstract: Systematic provenance analysis of the Late Triassic strata in the Helan Mountain area have been performed, based on the
geological conditions, thickness variation, and major and trace elements. Results show that sediments of the Late Triassic Yanchang
Formation in the Helan Mountain were mainly derived from its northwest, west, south and east in the early stage (the lower two
members) and from its northwest, west and south in the later stage (the upper three members). In this study, we systemically compare
the effectiveness of various major and trace elements as provenance indicators. Analysis of the major elements /UCC, main elements of
discriminant function diagram, trace elements /UCC, La/Th and Hf, Co/Th and La/Sc，Th/Sc and Zr/Sc discrimination diagrams, and
Th/U and Th discrimination diagram yields largely similar results in term of indicating provenance, though differences exists. Besides
the above indicators, analysis of lithological discriminant, CIA index, Eu anomaly, and Rb/Sr discrimination can also provide effective
information for provenance, and can be used as important indicator for judging the complex provenance compositions. This paper
provides details about the advantages and disadvantages of various methods for provenance analysis by major and trace elements and
draws some new insights, which provided a scientific basis for further improving provenance analysis.

Key words: Helan Mountain, Late Triassic, major and trace elements, provenance spatial-temporal evolution