宁芜盆地玢岩型铁矿床的成矿时代：金云母40Ar-39Ar同位素年代学研究

宁芜盆地是长江中下游成矿带的重要组成部分,盆地内广泛产出玢岩型铁矿床,但其精确的成矿时代及其形成构造背景研究仍十分薄弱.本文在详细野外地质工作的基础上,选择与磁铁矿密切共生的金云母为对象,利用40Ar-39Ar阶段加热同位素定年方法,对盆地内典型玢岩型铁矿床进行了成矿时代研究,确定了盆地内主要玢岩型铁矿床陶村、白象山和...

Geochronology of the Porphyry-like Type Iron Deposits in Ning-Wu Basin: Evidence from ~(40)Ar-~(39)Ar Phlogopite Dating

The Ning-Wu Basin is the important parts of the Middle-Lower Yangtze River Valley metallogenic belt, where there are widespread porphyry-like type iron deposits. However, the researches on precise ore-forming epoch and tectonic setting are very weak. Based on detailed field geological work, we present new 40Ar-39Ar phlogopite ages for the typical Taocun, Baixiangshan and Hemushan iron deposits to constrain the timing and duration of mineralization in the basin. Phlogopite from the Taocun, Baixiangshan and Hemushan iron deposits yielded 40Ar-39Ar plateau ages of 129.3±1.1Ma, 130.7±1.1Ma and 129.1±0.9Ma, respectively. The dating result indicates that different porphyry-like type iron deposits in the Ning-Wu Basin are all formed in early stage of Early Cretaceous about 130Ma and obviously later than skarn-porphyry Cu-Au deposits related to high-k calc-alkaline intrusions in uplift areas. The porphyry-like type iron deposits in Ning-Wu volcanic basin were thought to be formed under regional lithospheric and thinning environment.