Spectral Characteristics of Rock Varnish from Arid and Humid Regions in China

为探究岩石漆矿物组成在空间上的变化规律,采集了中国干旱、半干旱及湿润地区岩石漆样品,制作了岩石漆纵切片观察其形貌特征,对其进行了拉曼光谱与红外光谱分析.光谱学研究表明,所有岩石漆样品均检测出574 ～ 594 cm-1、622 ～645 cm-1的拉曼峰位和428 cm-1、466～ 468 cm-1、513 cm-1的红外峰位,表明水钠锰矿是岩石漆中普遍存在的锰氧化物矿物.干旱与部分半干旱地区岩石漆检测出290～291 cm-1、405 ～ 409 cm-1、610 cm-1的拉曼峰位,半干旱地区岩石漆检测出217 cm-1、275 ～ 279 cm-1、393 ～ 395 cm-1的拉曼峰位,表明干旱地区岩石漆内铁氧化物以赤铁矿形式产出,半干旱地区富含针铁矿与赤铁矿.湿润地区岩石漆未检测到铁氧化物的谱峰信号.说明气候差异与生物活动可能是岩石漆形貌与矿物组成差异性的原因.Rock varnish collected from arid,semiarid and humid regions of China was studied by Raman and infrared spectroscopy to explore its mineralogical variation.Spectral results show that Raman peaks at 574-594 cm-1,622-645 cm-1 and infrared peaks at 428 cm-1,466-468 cm-1,513 cm-1 can be detected in all samples,which indicates that birnessite is the common manganese oxides phase in rock varnish from different locations.Raman peaks at 290-291 cm-1,405-409 cm-1 and 610 cm-1can be detected in rock varnish from arid and partial semiarid regions,while Raman peaks at 217 cm-1,275-279 cm-1 and 393-395 cm-1can be detected in varnish from semiarid regions,suggesting that iron oxides in rock varnish from arid areas occur as hematite and iron oxides in rock varnish from semiarid area soccur as hematite and goethite.Iron oxides in rock varnish froin humid areas is not detected,suggesting a very limited content.Climate difference and biological activity may contribute to the morphological and mineralogical diversity of rock varnish from various environments.国家自然科学基金重点项目; 国家重点基础研究发展计划; 国家自然科学基金项目; 国家自然科学基金优青项目中国科学引文数据库(CSCD)2299-3073