地质找矿论丛2017，Vol.32Issue(1)：42-49,8.DOI:10.6053/j.issn.1001-1412.2017.01.006
北京密云沙厂BIF型铁矿地质地球化学特征与成矿时代
Geochemical characteristics and metallogenic age of BIF type Fe deposit at Shachang in Miyun County, Beijing
摘要
Abstract
Shachang Fe deposit at Miyun county,Beijing is an Anshan-style iron deposit in Archean metamorphic rock series of the Miyun group characterized by BIF.The ore is banded and densely massive and dominated by magnetite quartzite type with w(Fe)=25％00～30％.The country rock includes mainly biotite-plagioclase gneiss,pyroxene granulite and plagioclase amphibolite and local tonalitic gneiss.The UPb age of the core of rim-core zircon (Th/U ratio＞0.4) from biotite plagioclase gneiss is dated at 2 619±25Ma and 2 544±16Ma respectively.The former represent the age of the protolith (basic volcanic rock) of biotite plagioclase gneiss as well as those of the volcanic eruption and deposition of BIF at Shachang,the latter the age of TTG emplacement and the reworking events.Major and trace element analysis of the biotite plagioclase gneiss is characterized by Rb、Ba、Sr enrichment and Th depletion suggesting that during deposition of BIF may occur a crustal accretion event at about 2 550 Ma.Therefore,we think that the Shachang iron deposit belongs to Algoma type and is one of the representatives of preliminary cratonization of the North China continental block and large-scale magmatic thermal events at end of Neoarchean Era.关键词
密云沙厂铁矿/条带状铁建造(BIF)/锆石U-Pb年龄/黑云斜长片麻岩/北京市Key words
Shachang Fe deposit in Miyun county/BIF/zircon U-Pb age/biotite plagioclase gneiss/Beijing分类
天文与地球科学引用本文复制引用
方同明,孙永华,程新彬,刘鸿,吴虎峻,魏波..北京密云沙厂BIF型铁矿地质地球化学特征与成矿时代[J].地质找矿论丛,2017,32(1):42-49,8.基金项目
中国地质调查局项目“北京区域地质调查片区总结与服务产品开发”(编号:12120113012900)、“中国矿产地质与区域成矿规律综合研究(中国矿产地质志)”(编号:1212011220369)、“北京市1∶ 100000区域地质图编制”(编号:dkjdzky2015003)联合资助. （编号:12120113012900）
