In situ LA-ICP-MS trace element analysis of magnetite from the late Neoarchean Gongchangling BIFs, NE China: Constraints on the genesis of high-grade iron ore
In situ LA-ICP-MS trace element analysis of magnetite from the late Neoarchean Gongchangling BIFs, NE China: Constraints on the genesis of high-grade iron ore
复制标题
中国东北新太古代晚期弓长岭 BIF 磁铁矿原位 LA-ICP-MS 微量元素分析：对高品位铁矿成因的制约
DOI：
10.1002/gj.3004
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发表时间：
2018
影响因子：
1.8
通讯作者：
Luan Yan
中科院分区：
文献类型：
--
作者：
Sun Xiaohui;Zhu Xiaoqing;Tang Haoshu;Luan Yan
前寒武纪带状铁地层（BIF）不仅与生命、海洋和大气的演化有关，而且还为世界各地提供了重要的铁储量。弓长岭铁矿床位于中国辽宁鞍本地区，属氧化相阿尔戈马型BIF矿床，弓长岭二号矿区是中国著名的高品位铁矿生产地。磁铁矿是弓长岭铁矿床的主要矿石矿物，磁铁矿主要呈现三种赋存模式：BIF（不含阳起石）、含阳起石BIF和高品位铁矿石。采用激光烧蚀电感耦合等离子体质谱法获取弓长岭铁矿不同产状磁铁矿的微量元素组成，以约束高品位铁矿的成因。与来自 BIF（不含阳起石）的磁铁矿相比，来自含阳起石 BIF 的磁铁矿显示出相对较低的 Mg、Al、Mn 和 Zn 含量，这表明共存矿物在磁铁矿中的微量元素浓度中发挥了重要作用。与 BIF（含/不含阳起石）相比，高品位铁矿石中的磁铁矿 Ti 和 V 含量较低，Al 和 Mn 含量较高，表明高品位铁矿石可能被高温变质热液重整。十字石-石榴石-黑云母片岩是高品位铁矿石的围岩，利用石榴石-黑云母地温测定法评价其变质温度为593±17℃。有人认为，区域变质作用过程中产生的变质热液改造了BIF，从而产生了高品位铁矿石。
The Precambrian banded iron formations (BIFs) not only relate to the evolution of life, ocean, and atmosphere but also provide important reserves of iron around the world. The Gongchangling iron ore deposit located in the Anshan‐Benxi area of Liaoning Province, China, is oxide facies Algoma‐type BIFs, and the Gongchangling No.2 mining area is famous for the production of high‐grade iron ore in China. Magnetite is the main ore mineral in the Gongchangling iron ore deposit, and the magnetite mainly exhibits three modes of occurrence: BIFs (without actinolite), actinolite‐bearing BIFs, and high‐grade iron ore. Trace elemental compositions of the magnetite with different occurrences of the Gongchangling iron ore deposit were obtained by laser ablation inductively coupled plasma mass spectrometry to constrain the genesis of the high‐grade iron ore. The magnetite from actinolite‐bearing BIFs shows relatively lower contents of Mg, Al, Mn, and Zn compared to the magnetite from BIFs (without actinolite), suggesting that coexisting minerals have played an important role in the trace element concentration in magnetite. The magnetite from high‐grade iron ore has lower contents of Ti and V and higher contents of Al and Mn than counterpart from BIFs (with/without actinolite), indicating that the high‐grade iron ore may be reformed by high temperature metamorphic hydrothermal fluid. The staurolite‐garnet‐biotite schist is the wall‐rock of high‐grade iron ore, and the garnet‐biotite geothermometry is used to evaluate the metamorphic temperature of 593 ± 17 °C. It is proposed that the metamorphic hydrothermal fluid produced during regional metamorphism reformed BIFs to generate high‐grade iron ore.