东疆红山Cu-Au矿床氧化带硫酸盐矿物穆斯堡尔谱特征及其意义

Mssbauer Spectra Characteristics of Eight Sulfate Minerals in Oxidization Zone of Hongshan Hs-Epithermal Cu-Au Deposit,Eastern Tianshan,NW China,and Their Geological Significance

穆斯堡尔谱对确定铁离子占位、核外环境及氧化态方面有着独特的优势。在红山铜金矿床氧化带硫酸盐矿物的XRD、TA、湿法化学分析和红外光谱测试的基础上,测定了板铁矾、针绿矾等8种硫酸盐矿物的室温57Fe穆斯堡尔谱,并根据常温下硫酸盐矿物穆斯堡尔谱参数和其晶体结构中Fe3+和Fe2+的占据位置对其谱峰进行了指派。结果表明本矿床氧化带硫酸盐矿物的穆斯堡尔谱的同质异能位移较小、四级矩分裂值分布范围较大、无磁超精细分裂等特征,且硫酸盐矿物结构中存在着共价键。通过与青海锡铁山铅锌矿氧化带硫酸盐矿物的穆斯堡尔谱相比较,两者在近地表风化及氧化过程中所处的物理化学条件基本相同,酸性和氧化性的环境为硫酸盐矿物的产生和保存提供了良好条件,但红山矿床更为干旱少雨,导致两者硫酸盐的穆斯堡尔谱参数略有不同。

Mssbauer spectra have the priority to define the site of Fe cation,environment outside of nuclear and oxidation value. Based on the research results obtained previously,for example XRD、TA、chemical analysis and infrared spectrum,the56Fe Mssbauer spectra of eight sulfate minerals from oxidation zone of Hongshan Cu-Au sulfide deposit in hyper-drought district have been determined at normal temperature in the paper. The results show that their Mssbauer spectra are characterized by the smaller isomer shifts,a wider distribution range of quadrupole splittings,and no magnetic hyperfine splitting,etc.. And based on the crystal structural analysis of eight sulfates minerals,we assigned the quadrupole splittings formed by the Fe3 + and Fe2 +cation in site respectively。It has the same physical and chemical conditions in the weathering and oxidation progress on the surface of Xitiehsna and Hongshan sulfide deposits,but the climate in hongshan deposit is much dryer,which results in the difference of Mssbauer spectra of sulfate minerals. The acidic and oxidable environments provide a good condition for the occurrence and conservation of sulfate minerals.