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The Ekou banded iron formation (BIF) in the Wutai area is hosted within the late Archean Baizhiyan formation. The mineral assemblage is used to identify oxide and silicate facies. The oxide facies is composed of magnetite and quartz, and the silicate facies is characterized by the presence of silicate minerals. A geochemical analysis shows that the major elemental compositions are dominantly SiO2 and Fe2O3T, with very little Al2O3 and TiO2 and minor abundances of incompatible elements and transition elements. These results indicate that negligible terrigenous materials were involved in the BIF deposition. The rare-earth elements (REEs), normalized by post-Archean Australian shale, exhibit the characteristics of light REE (LREE) depletion, heavy REE (HREE) enrichment, and positive La, Y, and Eu anomalies. The Y/Ho ratios are superchondritic. These results indicate that the material that formed the Ekou BIF originated from the mixing of seawater and submarine hydrothermal fluids. A Ce anomaly deficiency and heavy Fe isotope enrichment indicate that the Ekou BIF formed in an anoxic marine environment. The δ30SiNBS-28 values for quartz in the Ekou BIF are similar to those of other BIFs with distribution ranges of modern sinters and black smokers. The δ18OV-SMOW distribution is similar to that of hydrothermal sedimentary siliceous rocks. These results suggest that the formation of the Ekou BIF was closely connected to submarine volcanic exhalation activity. [ABSTRACT FROM AUTHOR]

Three NE-striking zoned polymetallic ore districts were found at the transition between the Shanhaiguan-Beizhen paleo-uplift and the Liaoxi depression at the midway point of the northern margin of the North China Plate. Although these deposits are located proximal to one another, they are metallogenic different and closely associated with the granite intrusions, and Au, Pb-Zn, and Mo are the major ore-forming elements. This paper investigates the rock/ore rare earth elements and trace elements and part of the whole-rock major elements of the Wenzhangzi Au-polymetallic deposit in western Liaoning Province. The results indicate that the andesite, granodiorite, and Au-rich polymetallic ore-forming fluids in the deposits exhibit the same crustal origin and closely associated with the Archean Au-rich crystalline basement. Granodiorite in the area tends to show a transition from quasi-aluminous to peraluminous → S-type granite, whereas the closely associated granite in the Yangjiazhangzi-Lanjiagou Mo metallogenic district is a differentiated I-type granite. These granites differ in age, with the former emplacing during the Mesozoic tectonic regime transition period and the latter emplacing during the intra-plate extrusion-uplift orogeny. [ABSTRACT FROM AUTHOR]