2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 10
Presentation Time: 4:15 PM


CHEN, Tianhu1, XU, Huifang2, XIE, Qiaoqin1, CHEN, Jun3, JI, Junfeng3 and LU, Huayu4, (1)Scholl of Natural Resources and Environmental Engineering, Hefei Univ of Technology, Hefei, 230009, (2)Department of Geology and Geophysics, Univ of Wisconsin, Department of Geology and Geophysics, University of Wisconsin, Madison, WI 53706, USA, Madison, WI 53706, (3)Department of Earth Sciences, Nanjing Univ, Nanjing, 210093, China, (4)State Key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences, No.10, Fenghui Nanlu, Xi'an, 710075, China, chentianhu168@vip.sina.com

Nano-rod calcites were discovered in loess-paleosol sequence with field emission scanning electron microscopy and transmission electron microscopy investigation for the samples of Duanjiapo, Luochuan, Lingtai and Xifeng Sections. Nano-rod calcites crystals arrange as bird net like. The mount of nano-rod calcites in loess is more than those of paleosol. Even though large amount of carbonate and various kind of autogenetic calcite in loess-paleosol sequence of China and nano-rod calcite in Tataouine meteorite in South Tunisia had been found, this kind of nano-rod calcites constituting main part of carbonate in loess-paleosol sequence and occurring widely in Chinese Loess Plateau was discovered first time. Diameters of the nano-rod calcites are 30~50 nanometer, length from hundreds nanometer to several micrometer. Nano-rod calcites crystals are roundness fiber, there are minute changed in thickness and minute bend along the direction of crystal length. Crystals of the nano-rod calcites present occasionally interlaced arrangement, arborization and frame by connection with right-angle among crystals. Electron dispersive spectrum shows the peaks of magnesium, phosphorous, and sulfur. Morphology and composition indicate that the formation of the nano-rod calcite is involved in matter derived from microorganism and biomineralization because of organic controlling to growth of calcite in loess deposit environment. Forming conditions of the nano-rod calcites should present paleoclimate, paleoenvironment and paleoecology. So, the discovery of nano-rod calcites in loess-paloesol sequence provide new route for reconstruct paleoclimate by oxygen and carbon isotope employing nano-rod calcites. It will be same important for nanogeoscience because it: (1) provides demonstration data of natural nanometer minerals occurring large mount to research microorganism nanometer mineralization and formation mechanism of natural nanometer minerals; (2) provide novel methods for the synthesis of nano-rod calcite as well as other minerals in material science. The work was supported by the Outstanding Overseas Chinese Scholars Fund of Chinese Academy of Sciences (2003-1-7) and National Science Foundation of China (40331001).