E-Net News

Xiao publishes article on Quaternary Sciences

Honglin Xiao, assistant professor of history and geography, has published a peer reviewed article on Quaternary Sciences.

2006 Vol.26 No.5. The article, “A Historical Event in a stalagmite from Yangzipo Cave, Guizhou, China”, studied a 18.6 cm long active stalagmite from Yangzhipo Cave, Guizhou Province in southern China. Thin section analysis revealed 125annual layers which could be identified by detrital grains at the top of each laye in the upper 4.1 cm of the stalagmite. Thin section studies also showed that the basal one-fourth part of the formation is predominantly aragonite while the upper, darker three-fourth section is largely calcite. The presence of aragonite is interpreted as the result of deposition in relatively dry or evaporative conditions at higher saturation states, and calcite is considered as the result of precipitation in wetter conditions at lower precipitation rates and saturation states.

Several dating methods including Pb210 dating of 4 samples at the Skidaway Institute of Oceanography, University of Georgia, and thermal ionization mass spectrometry (TIMS) U-series dating of 14 samples at the Department of Geology and Geophysics, University of Minnesota, USA, and annul layers counting were applied to obtain a reliable and accurate age for it. Pb210 analysis and annual layer counts in the upper part of the stalagmite indicate deposition at about 0.32mm/yr during about the last 125 years. Interestingly, the growth of the stalagmite about 125 years ago corresponds well with a farmer rebellion around AD1850. The variation on grey scale intensity, d18O and d13C was too great to be explained by the change in climate alone. Close thin section studies with additional field trips to Yangzipo Cave area revealed that the sharp change was at least partially influenced by a layer of wood detritus created by a historical event taken placed around the cave at that time. In this event, the rebels cut the trees above the cave to set up a fire to kill hundred villagers hiding inside. Electronic scanning microscopy study indicated that there was a clear carbon detritus layer recorded in the stalagmite, further confirmed our claim.

This study of a stalagmite from Guizhou Province in China suggest that stalagmites from this region may provide a high-resolution record of climate change and at the same time may also preserve information about land use/land cover therefore human activities above the cave.

David Hibbard,
Staff
11/15/2006 8:46 AM