摘要
国内外学者在航空高光谱矿物填图时,根据Al-OH光谱特征吸收波长位置不同将浅色云母类矿物分为2~3类,分别命名为高铝绢云母、中铝绢云母、低铝绢云母,但对它们的成因特点却只有零星的讨论,没有比较系统的有针对性的研究。本文在新疆雪米斯坦铀多金属成矿带获取CASI/SASI航空高光谱数据,并开展矿物填图的基础上,针对高铝绢云母、中铝绢云母、低铝绢云母等三种矿物的成因学专门开展了比较系统的研究。采用的方法主要是在开展详细的野外地质观察、采样的基础上,对采集的上述三类矿物蚀变岩样品进行详细的室内光谱测量、Al-OH吸收波长位置统计、显微薄片观察、全岩X衍射分析、粘土X衍射分析等研究,并结流体成矿理论和已有矿物成因学知识,进行了详细深入的分析讨论。研究表明,高铝绢云母蚀变岩蚀变强烈,云母类蚀变矿物以绢云母、伊利石为主,且主要与叶腊石和微晶石英等矿物伴生,而低铝绢云母蚀变岩蚀变强度中等,以伊利石、伊蒙混层为主,绿泥石增加,主要与方解石、浊沸石等矿物伴生;高铝绢云母蚀变岩具有相对高的石英含量和粘土矿物总量,具有相对较低的钾长石、斜长石以及方解石含量;低铝绢云母蚀变岩则具有相对较低的石英和粘土含量,具有相对较高的斜长石、钾长石和方解石含量。通过深入分析讨论,本文提出了在研究区航空高光谱识别的高铝绢云母形成于相对高温、偏酸性的热液流体环境,低铝形成于相对低温、偏碱性的热液流体环境。这一新认识对航空高光谱遥感矿物填图结果的深入应用和深层次找矿信息反演具有重要意义。
Researchers at both home and abroad divide mica minerals into two or three categories, which are named high-Al, medium-Al and low-Al sericites based on wavelength of spectral Al-OH absorption. Although some concern was paid on their minerageny, no systematic specific study has been carried out. With CASI/SASI airborne hyperspectral data obtained for the Xuemisitan area, and based on implementation of mineral mapping, a systematical comparison study was conducted on origins of high-Al, medium-Al and low-Al sericites. Based on field geological observation and sampling in the Xuemisitan area, this study analyzed samples of three kinds （high-Al, medium-Al and low-Al sericites） of altered rocks using hyperspectal measurement, AI-OH absorption wavelength calculation and statistics, microscope observation of thin section, X ray diffraction of bulk rock, and X ray diffraction of clay minerals. In combination with fluid metallogenic theory and minerageny, this study also analyzed their forming mechanism. The results show that high-Al sericite underwent intensive alteration and altered minerals of mica include sericite and illite, accompanied by pyrophyllite and fine-grain quartz. By contrast, low-Al sericite underwent medium alteration, and altered minerals are dominantly illite and andreattite, and more chlorite, with minor laumonite. High-Al sericite altered rocks contain relatively higher contents of quartz and clay, but relatively lower contents of K-feldspar, plagioclase and calcite than that of the low- Al series. Low-Al sericite altered rocks contain low contents of quartz and clay, but relatively high contents of plagioclase, K-feldspar and calcite. Combined with detailed mineralogy studies, this study concludes that the high-Al sericite identified by hyperspectral may form in the hydrothermal fluid environment with comparatively high temperature and slight acid and the low-Al sericite formed in fluid environment of comparatively low temperature and slight alkaline. This understanding is of great significance for application of hyperspectral mineral mapping information and interpretation of deep exploration information.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2018年第2期395-412,共18页
Acta Geologica Sinica
基金
中核集团龙腾二期项目"铀及多金属矿产勘查高光谱遥感综合应用示范研究"(遥LTY1604)
国家自然科学基金项目"航空高光谱识别的高
中
低铝绢云母成因机理研究"(41772354)联合成果
作者简介
叶发旺，男，1974年生，博士，高级工程师（研究员级），研究生导师，主要从事铀矿勘查遥感新技术研究及找矿应用工作。Email：yfwbeijing2008@sina．com。
