四川黄龙钙华沉积剖面的矿物学特征及其指示意义

Mineralogical Characteristics and Its Significance of Travertine Deposition Profile in Huanglong, Sichuan

摘要: 近年对四川黄龙沟地表水体的研究发现，现代黄龙钙华共生有大量硅藻、蓝藻等优势藻类种属和多类细菌种属。对微生物是否参与钙华沉积及其在沉积中的作用得到了国内外学者的关注。本文通过对黄龙钙华沉积剖面进行矿物学特征及指示意义的研究，以调查微生物是否参与了黄龙钙华的沉积和为揭示黄龙钙华的形成机理提供科学证据。XRD晶体结构精修解析表明，黄龙钙华为三方晶系方解石结构的单一物相，沿晶胞C轴存在拉伸，晶胞体积扩大的特征，与生物矿化作用形成的方解石晶胞特征一致。化学成分和热分析表明，历史钙华存在微生物参与钙华沉积的可能。但因地质作用的影响，本文未能发现保留完整微生物化石，从而为微生物参与黄龙钙华沉积提供直接证据。

Abstract: In recent years, the studies of surface water in Huanglong ravine, Sichuan Province find that mod-ern Huanglong travertine is symbiosis with abundant species of diatoms, cyanobacteria and mi-crobes. The role of biotic influence in mineralization of calcium carbon has gained attention of the scholars at home and abroad with the aim of ascertaining whether microbiological activity plays a relevant role in depositing fossil travertine. The presented study focuses on studying mineralogical characteristics and environmental significances in Huanglong travertine deposition profile. The objectives are exploring whether the microbes are involved in the deposition of Huanglong travertine and providing scientific evidence for revealing the possible Huanglong travertine for-mation mechanism. The crystalline refinement results of X-Ray Diffraction (XRD) identified the travertine in Huanglong was a typical single crystalline calcite with anisotropic lattice distortions of along axes of C, suggesting some level of metabolic mediation during mineralization. The chemical composition and IR spectra of the history of travertine indicated that the possibility of microbes participated in travertine deposition. However, because of the influence of geological pro- cesses, the presented study didn’t find intact microbial fossils which provided directly evidence.