Abstract:
In this paper, the authors studied the construct properties of volcanic rocks in the Late Paleoproterozoic period of Shanxi Province, which aims to provide references for the disagreements about boundary between Paleoproterozoic and Mesoproterozoic. The volcanic extrusive rocks of this period are unconformable on the crystalline basement with the character of active continental margin. Both of the Hangaoshan Group (Xiaolangling Formation) and the Xiyanghe Group (-Xionger Group) are extending to SEE direction, and the lava is absolute dominant, with occasional clastic rocks. Besides, the lava is mainly composed of fissures (beaded) and peaceful overflow eruptions, and the corresponding basic intrusive rock group was rising channel for the magma. The lithology is mainly andesite-basaltic andesite, with the lithology is mainly andesite and basaltic andesite, with a small amount of basalt and rhyolite. The rock phenocrysts are pyroxene and plagioclase, and occasionally composed of hornblende and biotite. The geochemistry of the rocks is rich in large ion lithophile elements and light rare earth elements, and low in high field strength elements, with
w(Th)>
w(Ta). The εNd(
t) and εHf(
t) values of the whole rock are negative, which are dominated by SH+HKCA series in the SiO
2-K
2O diagram and potassic volcanic rocks series. It is a continuation of the collision and cohere between the western and eastern continental blocks of the crystalline basement of the North China Craton in the Late and Middle Paleoproterozoic, which are the post-collision volcani arc magma.