【摘要】 我国北方洞穴石笋中发育双重光性微层（透光微层和发光微层），两种微层可以相互对应，但也存在不相匹配的现象。运用二次离子质谱分析微层内物质组分，发现透光微层的浅色段含有相对丰度较高的Mg和Sr元素以及小分子有机质，而Ba和Fe及大分子有机质主要赋存于微层内暗色段，层内暗色物质包含有机质和粘土物质。微层物质组成和成因等方面的研究可以反映气候变化的高分辨率信息。更多还原

【Abstract】 Speleothems can be a valuable high-resolution record of terrestrial paleoclimate,especially for the larest 2 000 years. Research has tended to focus on characteristics of microlayers formed along the growing axes of stalagmites and can be identified under microscopes. It has been supported that the microlayers almost are annual layers by TIMS-U series, AMS 14C and other dating methods.Since 1994, we have obtained many stalagmites from the East China. All stalagmite samples were cut along the growth axes, then 1mm tO 0.1mm polished section were made and observed under microscopes. Most of the deposits, especially the stalagmites in North China, contain microlayers. Bi-optical microlayers of the samples of stalagmites from Water Cave and Shihua Cave can be observed under transmitted light and fluorescent respectively, and so called transmitted-light microlayers and luminescent microlayers. Range of thickness for transmitted-light microlayers is 101 to 102 μm. The layer mostly has a white part at the bottom and a dark part on the top. Generally, the brightness of microlayer decreases gradually from the bottom to the top, and change abruptly to next microlayer. The luminescent intensity increases gradually from the lower to the upper part, and changes to next layer abruptly. These two kinds of microlayers are usually on the same location of the section. However, sometimes the numbers of the two types of the microlayers in same section are different.It seems that their causes are not the same. Under the transmitted light, the non-trallsparent dark matter can reflect and refraCt the normal light so the bosAnttedw-light microlayers are observed. The dark matter includes OM (organicmatter) and clay detritUs. Under the excitahon of fluorescent light OM can becomeluminescent such as the humic / fulvic acid, so the luwhnescent microlayers are aPPearing. OM usually is non-tfapsparent but some organic moleculars, with small and simple stwtLlres, can be transparent. In shoyt words, the dark matter in transmitted-light microlayers are not completely the luminescent OM. Secondary ion mass spectrometry (SIMS) can help in situ analysis with high spahal resoluhon and high measurement precision. To understand the sedimentary mechanism of hi-ophcal ndcrolayers in stalagmites, and find some proxies for climatic signal, we analyzed the componentS of the whcrolayer by TFS-2000 LMIG/TOF SIMS.5 points from the bottom tO top of a ndcrolayer have been measured for sample TS9701. T’he resultS are reported as the ratios of several positive secondary ions tO .’Ca. We found that there are more "Mg, "Sr and small moleculars of OM (organic matter) in the light part of the microlayer than the dark pat. HOwever, "Fe and "’Ba are a little higher relahve to lighter part. Based on our resultS, we expect that the light part of ndcrolayer was formed in summef, and the dark part was formed in winter. In summer, because of a heavy rainfall and high temperatllre, there is a maximum content of CO, in the soil, and OM can be decomposed quickly to small moleculars, such as alkane, alkene, and benzene. They are transparent and less luminescent. But in winter, there is a lower discharge and lower temperatUre, OM is decomposed slowly, more large moleculars can be brought into cave through drip water. They can be lundnescent when excited aam ac. Mg, Sr can enter into the crystal structUre of carbonate due to their similar ionic radiuses tO Ca. Ba has larger ionic radius than Ca, and Fe has very differentgeochendstry characters from Ca, so it is a little more difficult for them tO rePlace Ca.But they can form complexes with OM and some clay dineral. This can increase thedark level in microlayer.The dark boundary of microlayers was probably formed by the precipitahon ofOM and clay detritlls washed down from the soils and fissures of rocks by thebeginning several rainfalls. In the wet season, usually in stimmer in East Asia, Cobcontent increases tO the highest in soil. When the CaCO, precipitation at is largestthe light pall of microlayers is formed. In the dry season, i.更多还原