| 贵州拉丁晚期扬子台地边缘地表暴露带的特征及裂隙中微型钟乳石的成因 |
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| 关键词:platform margin exposure belt micro-stalactite carbon and oxygen isotope composition Late Ladinian |
| 基金项目:国家重点基础研究发展规划项目(编号G1999042310) |
| 作者 | 单位 | | 肖加飞 | 中国科学院地球化学研究所矿床地球化学开放实验室,贵州贵阳,550002；中国科学院研究生院,北京,100039
贵州省区域地质调查研究院,贵州贵阳,550005 | | 魏家庸 | 贵州省区域地质调查研究院,贵州贵阳,550005 | | 胡瑞忠 | 中国科学院地球化学研究所矿床地球化学开放实验室,贵州贵阳,550002 |
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| 摘要: |
| Characteristics of Superficial Exposed Belt on the Margin of the Yangtze Platform in the Guizhou in Late Ladinian Period and the Genesis of Micro-Stalactites in Fissures |
| The superficial exposure belt experienced a long evolutionary time(about 1 Ma ),and formed a great thickness of sidiments(usually between 100～150 m,with the largest thickness being some 180 m) during Late Ladinian period of Middle Triassic. There exist very clear exposure features,such as vadose pisolite,fenestral(birdeye) structure,middle-large type teepee structure and karst breccia. The belt is therefore evidently a calcareous weathering crust under humid-semihumid climate condition in an ancient upwarped region. There are three types of micro-stalactite in fissures of the exposed belt,namely,drapestone,dripstone,and flostone. Their 18 O isotope composition is usually about -10‰(PDB),and their 13 C isotope values are generally between 1.5‰-2‰(PDB).The 18 O isotope composition indicates that micro-stalactites are of fresh-water origin,but their 13 C values are slightly higher than the values of the freshwater sedimentary. This is probably attributed to the fact that meteoric water dissolved pre-formed limestone (bedrock) and obtained 13 C.The three shapes of the micro-stalactite are petrologically typical of fresh-watter sediments .It is thus considered that the micro-stalactites are fresh water sediments. |
| XIAO Jia-fei,WEI Jia-yong,HU Rui-zhong.2004.Characteristics of Superficial Exposed Belt on the Margin of the Yangtze Platform in the Guizhou in Late Ladinian Period and the Genesis of Micro-Stalactites in Fissures[J].Acta Geoscientica Sinica,25(2):177-180. |
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