北京石花洞石笋中有机质的赋存状态  

Occurrence of organic matter in stalagmite from Shihua cave,Beijing

作　　者：贾蓉芬[1] 蔡炳贵[2] 班凤梅[2] 刘德汉[1] 

机构地区：[1]中国科学院广州地球化学研究所有机地球化学国家重点实验室,广东广州510640 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球化学》2007年第2期193-199,共7页Geochimica

基　　金：国家自然科学基金(40472091);国家重点基础研究发展计划项目(2004CB720206)

摘　　要：选取北京石花洞石笋磨制成光薄片,对它进行了显微镜透射光、反射光和荧光观测。镜下见有两类有机质:一是发黄绿色荧光以富啡酸为主的腐殖酸类有机质,主要赋存在碳酸盐结晶程度差、溶孔发育的暗层或裂隙中;二是粒径小于30μm的碎屑状固态有机质,它们不发荧光,不均匀地聚集在暗层溶孔周边、暗层与亮层过渡区或亮层内的溶解裂隙中。碎屑状固态有机质的反射率Ro为6.72%～6.82%,拉曼光谱为典型石墨类单峰,分析表明,碎屑状固态有机质可能主要来自洞穴上覆土壤或已风化的煤系地层,被较强水流携带进入洞穴,与碳酸钙一同沉积,从而保存在石笋中。石笋微层中暗层与雨期、亮层与干期相对应,石笋中固态有机质的富集带可作为水动力突然变强或“事件”的标志。有机质常为金属离子或金属化合物的载体,不同地区石笋中有机质的研究也将有助于对气候变化多指标研究获得共识。A polished thin section made from the layers developed and rich in organic matters in a stalagmite from Shihua cave was observed under the microscope of transmission, reflex and fluorescence. Two types of organic matters are found： one is mainly humic acid with yellow-green fluorescence, and occurred in dark layer, where the carbonate has poor degree of crystallization and water-eroded caves develop, and the other is elastic particles less than 30 μm, with no fluorescence, and occurred around the cave in the dark layers in the transitional parts between the dark and bright layers, as well as in the dissolved fracture of bright layer. The organic clastic particles show high evolution with a reflectivity （R°） of 6.72% -6. 82%, and have a typical single peak of graphite in the Raman spectra. Apparently, the organic matters in stalagmite are mainly from soil and weathered coal measure strata around the Shihua cave and were carried into the cave by running water. The dark layer corresponds to rainy period and the bright layer to aridity one in the carbonate sequences of the stalagmite. The belt enriched in organic elastic particles is an indication of sudden increase of water current or an event . often a carder of metallic elements or compounds, the research on organic matters in Since the organic matter is stalagmite of different areas will help to reach an understanding of multiple proxy indicators of climate variation from the study of stalagmites by different methods.

关 键 词：石笋 微层 发荧光的有机质 碎屑状固态有机质 雨期 干期 石花洞 北京 

分 类 号：P593[天文地球—地球化学]