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鞍山-本溪地区鞍山群含BIF表壳岩形成时代新证据:锆石SHRIMP U-Pb定年 被引量:17

Formation Age of BIF-Bearing Anshan Group Supracrustal Rocks in Anshan-Benxi Area:New Evidence from SHRIMP U-Pb Zircon Dating
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摘要 鞍本是华北克拉通最为重要的BIF铁矿集中区之一,BIF赋存于鞍山群表壳岩中.通过对广泛分布的鞍山群表壳岩的12个样品进行锆石SHRIMP U-Pb定年,大都获得2.50~2.55Ga岩浆锆石年龄,一些岩石中存在2.7~3.5Ga碎屑锆石或外来锆石.一些东北部(东部)岩石记录了新太古代晚期-古元古代早期变质锆石年龄.结合前人研究成果,可得出如下结论:(1)鞍本地区广泛分布的鞍山群含BIF表壳岩形成时代为新太古代晚期;(2)鞍山群表壳岩形成于陆壳基底之上.该研究进一步支持了已有认识:鞍本为东部古陆块西缘新太古代晚期巨型BIF成矿带的重要组成部分,稳定的构造环境有利于大规模BIF形成. Anshan-Benxi is one of the most important BIF concentration areas in the North China Craton,the BIF occurred in the Anshan Group supracrustal rocks.Using SHRIMP U-Pb zircon dating technique,12 supracrustal samples of the Anshan Group were analyzed.Most samples present 2.50-2.55 Ga zircon ages and 2.7-3.5 Ga detrital or xenocrystal zircons are observed in some samples.Combined with previous studies,main conclusions can be drawn as follows.(1)The widespread BIF-bearing Anshan Group supracrustal rocks in the Anshan-Benxi area were deposited during the Late Neoarchean.(2)The Anshan Group supracrustal rocks were formed over a continental basement.This study confirms that Anshan-Benxi is an important conponent of the huge Late Neoarchean BIF belt along the western margin of the eastern ancient terrane,and stable tectonic environment seems to be a key factor for the formation of huge-scale BIF ore deposit.
出处 《地球科学》 EI CAS CSCD 北大核心 2018年第1期57-81,共25页 Earth Science
基金 国家自然科学基金(No.41472169) 科技部基础专项(No.2015FY31010) 中国地质调查局项目(Nos.DD20160121-03 121201102000150012)
关键词 鞍山群 新太古代 锆石SHRIMP U-PB定年 鞍山-本溪地区 岩石学 Anshan Group Neoarchean SHRIMP U-Pb zircon dating Anshan-Benxi area petrology.
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