蚀变矿物的偏振光谱学研究

地物和大气中目标的反射、散射、透射及辐射具有的偏振特性，可以用于解决部分传统光学探测器无法解决的问题，已被广泛应用在军事、环境、农业、医药等诸多领域。在地质学方面，前人对偏振特性的研究主要集中在岩石学上，即利用岩石的偏振特性区分不同的岩石类型，以及通过造岩矿物的偏振差异解释导致岩石偏振差异的内因。这些研究为基础地质的岩性解译工作提供了重要参考。然而，在地质学另一重要分支--矿床学领域，有关偏振特性的研究还十分薄弱。由于矿床学关注蚀变矿物和蚀变带，如不掌握蚀变矿物的偏振特征，偏振技术将无法在矿床学领域得到推广和应用。针对前人在蚀变矿物偏振特性研究上的不足，在传统可见光光谱测量基础上，利用自主研发的偏振光谱测量系统和数据处理软件，以9种斑岩型矿床蚀变带中的特征蚀变矿物、3种短波红外盲区蚀变矿物、2种可见光盲区蚀变矿物为研究对象，开展了系统的偏振光谱测量和对比研究。结果表明：斑岩型矿床的钾化带、青磐岩化带、绢英岩化带和高级泥化带特征蚀变矿物在偏振光谱上存在较为明显的不同，表现为偏振曲线的对称性、变化趋势和偏振度强度三方面的差异，可据此对不同蚀变矿物进行识别，进而划分蚀变带。研究还发现：石英、萤石、钾长石三种短波红外盲区矿物，以及方解石、白云石两种可见光盲区矿物的偏振特性存在明显差异，说明通过给光谱仪增加偏振系统可有效提高光谱仪辨识矿物的能力，这对研发新一代小型化光谱仪，以及将光谱仪运用于矿产勘查具有重要的指导意义。该研究还说明，偏振光谱在矿床学领域具有重要的研究价值，在矿产勘查方面具有很大的应用潜力，应当积极开展更为深入、系统的研究和实践。

Study on Polarization Spectroscopy of Alteration Minerals

Objects on the ground or in the atmosphere have unique polarization characteristics when they reflect,scatter,transmit,and radiate,which can be used to solve problems that some traditional optical detectors cannot,and increase the information richness.Polarization characteristics of targets have been widely used in military,environment,agriculture,medicine and many other fields.In geology,previous pieces of literature about polarization mainly focused on petrology study,in which the polarization characteristics of rocks or rock-forming minerals were used to distinguish different rock types or to explain the mechanism of differences in rock polarization properties.Though the achievements provide important references for lithological interpretation in geological mapping,no focuses on economic geology,another important branch of geology.Since ore deposits are usually associated with alterations,it is of great scientific value and economic interest to study the polarization characteristics of alteration minerals,so that the polarization spectral technology can be used to guide ore prospecting work.In this study,we carried out polarization spectral measurement and data processing for nine porphyry-related,three that cannot be distinguished by shortwave infrared,and two that cannot be distinguished by visible light alteration minerals using instrument and software developed by Beijing Research Institute of Uranium Geology in an attempt to fill the blank on polarization characteristics of alteration minerals.The results show that the polarization spectra of alteration minerals in the potassic,propylitization,sericite and advanced argillic zones of porphyry deposits are significantly different.The differences in spectral shapes and absorption intensities can be used to identify different alteration minerals,thus divide the alteration zones.The results also suggest that the polarization characteristics of three shortwave infrared blind minerals of quartz,fluorite,and potash feldspar,and two visible-light blind minerals of calcite and dolomite are significantly different,implying that a spectrometer with polarization system can identify more kinds of alteration minerals,which further implying a new generation of micro spectrometers with polarization system could be very useful in mineral exploration.Consequently,it is necessary to carry out more further and systematic research and practice on polarization characteristics of alteration minerals.