航空成像光谱的蚀变信息提取技术

Extraction of Alteration Information Based on Airborne Hyperspectral Image

根据成像光谱仪CASI/SASI的影像特点,制定了高光谱影像的处理方法流程,介绍了各步骤的内容和需要注意的事项。阐述了噪声和坏波段去除、大气校正的过程,并提出了一些经验性的处理方法。在成像光谱岩石蚀变提取算法中,根据经验对已有方法进行了改进;在基于特定算法的矿物填图方法中,依据柯坪地区CASI影像中富含二价铁的辉绿岩脉的光谱特征,提出了富二价铁岩石提取算法。经过实地验证,富二价铁岩石的提取对铀矿勘探具有较好的指导作用。通过提取的信息结果与已经矿区或矿点的空间叠加分析发现,富二价铁岩石空间分布与铀异常点分布有很强的相关性。根据富二价铁与铀矿的空间分布规律,提出了断裂+富二价铁岩石的成矿模式。红色砂岩提供铀源,岩脉提取铀成为存储容器。富二价铁岩石提供铀沉淀催化剂的作用,且线性的富二价铁岩石分布区域对成矿更有利。通过富二价铁岩石的提取,在柯坪南部地区新发现了3条铀异常带。

Based on CASI/SASI images＂ characteristics, lhe hyperspectral images processing procedure is established. The contents of each step and things, which should be paid attention to, are introduced. Before the extraction of alteration inforniation, the data pre- processing should be well completed, the type of alterations in the study area should be determined, and the corresponding spectral database should be built. Some empirical approaches are made for those processing. Based on the experience, the various methods are described in detail and some algorithms are improved. Based on the spectrum characteristics of the rock containing ferrous iron-rich on the CASI images of Keping area, the ferrous iron-rich rock extraction algorithms are proposed. The field work has proved that the alteration information extracted is correct, and the extraction of ferrous iron-rich is a good guidance for uranium exploration. The rule determining the mineralization model in the study area is found through the alteration information extraction and spatial superposition analysis on mine points or mineral area. The special distribution of ferrous iron-rich rock has a strong correlation with the uranium abnormal. In the study area, the red sand rock is the passage for uranium, the dyke is the storage for uranium, and the ferrous iron-rich rock makes uranium settle around the dyke. Three new dykes of uranium abnormal are found in south part of Keping using the method.