河北省邢台白涧铁矿床成矿作用研究

白涧铁矿床赋存于燕山期闪长岩和中奥陶统灰岩接触带中,空间上与矽卡岩密切相关; SIMS锆石U-Pb定年结果表明,含矿闪长岩加权平均年龄为128.47±1.2 Ma(MSWD=0.65, 95%置信度),代表白涧铁矿床形成的上限年龄;闪长岩Fe同位素组成的变化范围为δ⁵⁶Fe=+0.043‰~+0.166‰,平均值为0.0915‰±0.019(2SD, n=8);矽卡岩Fe同位素的变化范围为δ⁵⁶Fe=+0.058‰~+0.083‰,平均值为0.0707‰±0.019(2SD, n=3);灰岩Fe同位素的变化范围为δ⁵⁶Fe=-0.157‰~+0.042‰,平均值为-0.0575‰±0.019(2SD, n=2);磁铁矿Fe同位素的变化范围为δ⁵⁶Fe=+0.114‰~+0.146‰,平均值为0.1334‰±0.019(2SD, n=5);黄铁矿-磁黄铁矿Fe同位素的变化范围为δ⁵⁶Fe=+0.242‰~+0.270‰,平均值为0.2617‰±0.023(2SD, n=3)。闪长岩、矿石和矽卡岩Fe同位素组成的时空演化特征表明它们为同一流体体系演化的产物,具有相同的物质来源,来自于岩浆流体;白涧铁矿矽卡岩型矿体为燕山期华北克拉通破坏过程中岩浆流体成矿作用的产物。

Metallogenesis of Baijian iron deposit in Xingtai,Hebei

The Baijian iron orebody occurs between the Yeshan diorite and Middle Ordovician limestone, the distribution of the ore bodies is spatially related to skarn. By High-precision SIMS zircon U-Pb dating, we obtained the concordant age of 128.47±1.2 Ma(MSWD=0.65)for diorite, it indicates that the upper age of Baijian iron deposit. The δ⁵⁶Fe values of diorite range from+0.043‰ to+0.166‰, with an average of 0.0915‰±0.019(2SD, n=8). The δ⁵⁶Fe values of skarn range from+0.058‰ to+0.083‰, with an average of 0.0707‰±0.019(2SD, n=3). The δ⁵⁶Fe values of limestone range from-0.157‰ to+0.042‰, with an average of-0.0575‰±0.019(2SD, n=2). The δ⁵⁶Fe values of magnetite range from +0.114‰ to +0.146‰, with an average of 0.1334‰±0.019(2SD, n=3). The δ⁵⁶Fe values of pyrite and pyrrhotite range from+0.242‰ to+0.270‰, with an average of 0.2617‰±0.023(2SD, n=3). Evolution of Fe isotope suggest that ores and skarns resulted from the same magmatic fluid system and Fe element came from the same magmatic source.