矿床地质2012，Vol.31Issue(5)：1067-1074,8.
新疆西天山查岗诺尔铁矿床成矿时代——来自石榴子石Sm-Nd等时线年龄的信息
Metallogenic epoch of Chagangnuoer iron deposit in western Tianshan Mountains, Xinjiang: Information from garnet Sm-Nd isochron age
摘要
Abstract
The large-size Chagangnuoer iron deposit is hosted in andesite and andesitic volcaniclastic rocks in the middle-upper part of Carboniferous Dahalajunshan Formation, with widespread high hydrothermal alteration (represented by garnet) distributed extensively around the uppermost ore body Fel. The precise formation age of high hydrothermal alteration is the key to judging whether iron metallogeny was related to volcanism or intrusive activity. Garnet, which had a closely genetic relationship with magnetite, was formed simultaneously with or slightly earlier than magnetite. Garnet Sm-Nd isotope analyses reveal that 147Sm/144Nd values vary between 0.2792 and 0.5481 while 143Nd/144Nd ratios vary between 0.512950 and 0.513501. Data of seven isotope sam- pies form a good linear fitting relationship, yielding the Sm-Nd isochron age of (316.8 ± 6.7) Ma, which represents the formation epoch of high-temperature hydrothermal alteration. The result indicates that magnetite in-tergrown with garnet was formed at the late stage of Early Carboniferous period. Therefore, the iron metalloge-ny and high hydrothermal alteration might have resulted from the metasomatism between the post-magmatic hydrothermal solution derived from eruption of Dahalajunshan Formation volcanic rocks and the underlying marble, rather than the skarnization caused by the reaction between magmatic hydrothermal solution from Permian intrusion and marble in the ore district.关键词
地球化学/成矿时代/石榴石Sm-Nd等时线年龄/查岗诺尔铁矿/西天山/新疆Key words
geochemistry/ metallogenic epoch/ garnet Sm-Nd isochron age/ Chagangnuoer iron ore deposit/Western Tianshan Mountains/Xinjiang分类
天文与地球科学引用本文复制引用
洪为,张作衡,李华芹,李凤鸣,刘兴忠..新疆西天山查岗诺尔铁矿床成矿时代——来自石榴子石Sm-Nd等时线年龄的信息[J].矿床地质,2012,31(5):1067-1074,8.基金项目
本文得到国家重点基础研究发展计划(2012CB416803)、国家科技支撑计划(2011BAB06B02-05)和地质矿产调查评价项目(1212011085060)联合资助 （2012CB416803）
