We summarize the characteristics of sedimentary cycles, cycle interface types of some stalagmites and related significances in climatic, environmental and geological sciences. Before that, the components and structures of some typical large stalagmite in southern China were studied. Also 210 isotopic samples of δ13C, δ18O, 20 samples for U series dating in D10 and some related trace elements were analyzed comparatively. According to the colors reflected by different impurities in carbonate, the lamina features and isotopic components of stalagmite in D10, three cycling features which are accordant parallel, unaccordant parallel and unaccordant unparallel can be divided. 19 sedimentary cycles can be identified. The average δ13C, δ18O value - 3. 91 %PDB and -6- 97 %PDB respectively represent the threshold values which indicate the evolution of cold and warm climate. Consequently, if the isotopic value is higher than the threshold value, it means the climate is in favor of cold conditions. According to the isotopic and cycle characteristics of the sedimentary, it is considered preliminarily that the 19 cycles deposited during the years from 352 930 to 99 410 in Libo area indicate a relatively complete process of the climate evolution in the fifth Ice Age of the Quaternary Ice Age series in China. The 50 000 years which is calculated from cycle 10 to cycle 15 is surmised as a continuous freezing glacial maximum. The cycle 1 and cycle 16 represents probably interglacial period which was relative warmer. Furthermore, there also existed 50 000 or 100 000 years scale climatic cycle during the period. It is demonstrated that there was glacial period in Libo area from 350 000 to 100 000 years ago. The prophase about 170 000 years was frigid climate, and during 350 000 years and 250 000 years period was even more frigid, however the ecological environment evolved normally. The metaphase about 50000 years was extremely frigid and the ecological environment evolved in favor of the arctic weather. The late stage about 30 000 years represented an extreme climate in which the abrupt change between cold climate and warm climate occurred frequently, the normal and mutational succession coexisted.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Dec 1 2009|
- Dongge cave