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| WEATHERING CHARACTERISTIC AND MECHANISM OF SEDIMENTARY PYROCLASTIC ROCKS AT THE BOTTOM OF EMEISHAN BASALT |
| XU Zemin |
| (Department of Civil Engineering，Kunming University of Science and Technology，Kunming，Yunnan 650224，China) |
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Abstract The spheroidal weathering of sedimentary pyroclastic rocks which deposited at the bottom of Emeishan basalt is intensive. The weathering extent is stronger evidently than that of the overlying basalt. The saprolited crust have spongy microtexture and are characteristic of high porosity，high intrinsic permeability，high specific water capacity，low specific yield and low density. Both of the sedimentary volcanic clasolite have a homothetic chemical composition. Also，the changes of chemical composition in the weathering process are nearly the same. The temperature fluctuation in vadose zone can form to tiny slot between different clasts. The condensated vapor water in the tiny slot dissolve the limestone clast firstly，and then a sponginess crust occur，whose water absorbability and storativity are stronger than other saprolized crusts. The liquid water which has been absorbed and stored in the sponginess crust can both ensures the dissolution of the pyroclasts in the crust itself and supports the spread of the weathering front. The weathering process of basic calcareous sendimentary pyroclast can be divided into two stages which can not be separated absolutely. In the first stage，limestone clasts are mainly dissolved and basaltic clasts are dissolved in second stage.
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Received: 15 September 2010
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| [1] 熊舜华，李建林. 峨眉山区晚二叠世大陆裂谷边缘玄武岩系的特征[J]. 成都地质学院学报，1984，(3)：43–63.(XIONG Shunhua，LI Jianlin. The characteristics of the late Permian basalts in the margin of continental rift in Emeishan area[J]. Journal of Chengdu College of Geology，1984，(3)：43–63.(in Chinese))
[2] 宋谢炎，王玉兰，曹志敏，等. 峨眉山玄武岩、峨眉地裂运动与慢热柱[J]. 地质地球化学，1998，(1)：47–52.(SONG Xieyan，WANG Yulan，CAO Zhimin，et al. Emeishan basalts，Emei tafrogeny and mantle plume[J]. Geology Geochemistry，1998，(1)：47–52. (in Chinese))
[3] 沈军辉，王兰生，徐林生，等. 峨眉山玄武岩的岩相与岩体结构[J]. 水文地质工程地质，2001，(6)：1–4.(SHEN Junhui，WANG Lansheng，XU Linsheng，et al. The lithofacies and the rock mass struature of Emei mountain basalt rockmass[J]. Hydrogeoloyg and Engineering Geology，2001，(6)：1–4.(in Chinese))
[4] 何 斌，徐玉刚，王雅玫，等. 东吴运动性质的厘定及其时空演化规律[J]. 地球科学(中国地质大学学报)，2005，30(1)：89–96.(HE Bin，XU Yigang，WANG Yamei，et al. Nature of the Dongwu movement and its temporal and spatial evolution[J]. Earth Science (Journal of China University of Geosciences)，2005，30(1)：89–96.(in Chinese))
[5] 钱壮志，徐翠玲，章正军，等. 滇东北地区峨眉山玄武岩铜矿成矿物质来源[J]. 矿物岩石，2007，27(1)：78–82.(QIAN Zhuangzhi，XU Cuiling，ZhANG Zhengjun，et al. Ore-forming source of copper deposits in Emeishan basalt area in northeast Yunnan province[J]. Journal of Mineralogy petrology，2007，27(1)：78–82.(in Chinese))
[6] 张云湘，骆耀南，杨崇喜. 攀西裂谷[M]. 北京：地质出版社，1988：141–197.(ZHANG Yunxiang，LUO Yaonan，YANG Chongxi. Panxi rifi[M]. Beijing：Geological Publishing House，1988：141–197.(in Chinese))
[7] 徐则民. 温湿气候区结晶岩与碎屑岩腐岩特征及其发育过程[J]. 地学前缘，2009，16(3)：364–373.(XU Zemin. Characteristics of aprolites formed from crystalline rock and clasolite in humid climatic regions and their development process[J]. Earth Science Fronties，2009，16(3)：364–373.(in Chinese))
[8] 徐则民，唐正光. 石灰岩腐岩的基本特征及其形成机制[J]. 地质论评，2007，53(3)：421–428.(XU Zemin，TANG Zhengguang. Principal characteristics of limestone saprolite and its forming mechanisms[J]. Geological Review，2007，53(3)：421–428.(in Chinese))
[9] 云南省地质矿产局. 云南省区域地质志[M]. 北京：地质出版社，1990：291–295.(Yunnan Bureau of Geology and Mineral Resources. Regional geology of Yunnan Province[M]. Beijing：Geological Publishing House，1990：291–195.(in Chinese))
[10] 四川省地质矿产局. 四川省区域地质志[M]. 北京：地质出版社，1982：363–365.(Bureau of Geology and Mineral Resources of Sichuan Province. Regional geology of Sichuan province[M]. Beijing：Geological Publishing House，1991：363–365.(in Chinese))
[11] 卢记仁. 峨眉地幔柱的动力学特征[J]. 地球学报，1996，17(4)：424–438.(LU Jiren. Dynamic characteristics of the Emeishan mantle plume[J]. Acta Geosceentia sinica，1996，17(4)：424–438.(in Chinese))
[12] 何 斌，徐义刚，肖 龙，等. 峨眉山大火成岩省的形成机制及空间展布：来自沉积地层学的新证据[J]. 地质学报，2003，77(2)：194–202.(HE Bin，XU Yigang，XIAO long，et al. Generation and spatial disttribution of the Emeishan large igneous province：new evidence from stratigraphic records[J]. Acta Geological Sinica，2003，77(2)：194–202. (in Chinese)) |
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2011, Vol. 30 
