1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. International Center for Geoscience Research and Education in Northeast Asia, Jilin University, Changchun 130026, China;
3. Tianjin Center of Geological Survey, China Geological Survey, Tianjin 300170, China;
4. Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang 065000, Hebei, China;
5. Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, China

Based on the study of geological characteristics of the deposit,the authors undertook zircon U-Pb dating and geochemical analysis of the representative trachyandesites in the host rock of the deposit,the results reveal:(1) six groups of single grained zircon U-Pb ages were obtained,of which �� is 2 422~2 683 Ma, for residual zircon ages, whereas �� to �� are 606~943 Ma, 428~437 Ma, 281~303 Ma and 169~221 Ma, respectively, for captured zircon ages. The zircon age of �� is 121~129 Ma, representing the formation of zircon in the processes of volcanism;(2) geochemical characteristics of major elements reveal that these volcanic rocks belong to high-potassium calc-alkaline series to shoshonite series;(3) trace elements and REE indicate that the rocks are characterized by enrichment of large ion-lithophile elements (LILE)(Rb,Ba,K, etc.) and light rare earth elements (LREE), but depletion of the HFSE elements (Nb,Ta,Ti, etc.) and heavy rare earth elements (HREE). Integrating all the relevant results,it is preliminary believed that there may exist a Paleoproterozoic-Neoarchaean basement or debris in the study area. The volcanism of this period was related to the partial melting of enriched mantle,magma intrusion and eruption in the tectonic background of lithospheric extension and thinning due to the subduction of the paleo Pacific Plate. The magma was contaminated by Early Jurassic intermediate-acidic intrusive rocks during the evolution process of rising. This magmatic activity is coincided with Early Cretaceous large-scale volcanic and magmatic events of Northeast China.