Geochemical Characteristics of REE and Trace Elements of Mesozoic Sedimentary Rocks and Its Tectonic Setting In Western Liaoning

There had been three-whole-gyre volcanic—sedimentary rocks during Mesozoic in Western Liaoning province. And lot of information on the crustal evolution can get from sedimentary rocks. We had determined the contents of REE and trace elements using the inductively coupled plasma mass spectroscopy (ICP-MS), and also utilized the discriminant diagrams of La—Sc—Th, Th—Sc—Zr for sedimentary tectonic setting. The results are: (1) the contents of REE were high in the Mesozoic sedimentary rocks, and the patterns were approximately consistent with post-Archean sedimentary rocks. (2) Trias sedimentary formations had the same normalized patters, however, the REE patterns of different sedimentary strata of Jurassic and early Cretaceous were dispersive, two and three types respectively, which reflected the change of provenance and the active tectonic setting. (3) the sedimentary tectonic setting during Mesozoic was mainly the continental island arc, and in Trias— Jurassic sometimes was the stable-passive continental margin. And in the period of early Cretaceous the setting was more active, sometimes with the characteristic of the active continental margin.