摘要
白石砬子钨矿位于'佳蒙地块'东段,主矿体赋存于燕山早期石英闪长岩与晚古生代青龙村群大理岩的接触带内,赋矿岩石为石榴石矽卡岩,成因上属矽卡岩型白钨矿矿床。矿区石英闪长岩中单颗粒锆石的LA-MC-ICP-MS定年结果表明:测点年龄值集中于195～205Ma,加权平均年龄为(198.27±0.80)Ma,成岩成矿作用发生于侏罗纪初期。岩石的主量元素组成具有低硅(58.07%～58.98%)、富碱(5.96%～6.41%)、富钠(3.65%～4.84%)、高铝(15.82%～17.89%)的特征,属准铝质富钠钙碱性系列;石英闪长岩REE总量较低((90.06～122.05)×10-6),以LREE相对富集、轻稀土和重稀土分异明显和较弱的铕异常为特征;结合高Sr、低Yb以及接近于原始地幔的Rb/Sr和Rb/Ba比值认为,石英闪长岩起源于俯冲板片的深部或加厚下地壳的下部(>40km)。综合本次研究和区域构造格局演化资料,初步认为白石砬子石英闪长岩的成岩成矿作用发生于古亚洲构造域和环太平洋构造域叠加和转换期,与以佳木斯地体为代表的中亚造山带东部地体群的俯冲-拼贴有关。
Baishilazi skarn tungesten deposit is located in the eastern part of Jiamusi-Xingmeng terrain.The major ore body occurs along the contact zone between the Early Yanshanian quartz diorite and the marble of the Late Paleozioc Qinglongcun Group.The host rock of the ore deposit is dominated by the garnet skarn.Using the LA-MC-ICP-MS single-zircon U-Pb dating method,the authors determined the ages of zircon grains separated from the intrusion,which are mainly from 195 Ma to 205 Ma with an average value of（198.27±0.80） Ma.Both the quartz diorite and its associated ore deposit were formed at the beginning of the Jurassic period.Major element geochemistry is characterized by low SiO2（58.07%-58.98%） and high alkaline（5.96%-6.41%）,sodium（3.65%-4.84%） and aluminum（15.82%-17.89%）.The quartz diorite belongs to the high-potassium and calcium system.Based on the features of low REE content（90.06×10-6-122.05×10-6）,high LREE and LREE/HREE ratios and low positive or negative Eu anomalies,it can be concluded that the quartz diorite was derived from the deep-crust source.As the quartz diorite has high Sr and low Yb content and its Rb/Sr and Rb/Ba ratios are similar to those of the primary mantle,it is inferred that the rock-forming materials were derived from the deep part of the subduction plate or the thickened lower crust（40 km）.In the light of geochronology and geochemistry of the Baishilazi intrusion in combination with regional tectonic evidence,the authors hold that both the intrusion and the associated tungsten deposit were formed during the transforming period between the Paleo-Asian tectonic belt and the Circum-Pacific accretion belt and related to the collision and collage of the terrain group represented by Jiamusi and Songnen massifs in the eastern Central Asian Paleozoic orogenic belt.
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2011年第6期1726-1735,1744,共11页
Journal of Jilin University：Earth Science Edition
基金
中国地质调查局项目(1212011085485)
吉林大学基本科研业务费项目(200903025
201004001)
中国科学院地球化学研究所矿床地球化学国家重点实验室开放基金(200910)
