| 苏、浙、皖边界地区长兴组底部砾岩的时代问题及其意义 |
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| 作者姓名： | 姚伦淇 |
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| 作者单位： | 同济大学海洋地质系 |
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| 摘 要： | 本区长兴组底部普遍发现一薄层砾岩,经酸解分析,内含丰富的牙形刺和鱼牙化石。根据化石确定,此层砾岩在不同地区为不同时代:浙江长兴煤山,砾岩时代为晚二叠世早期之末;安徽广德独山和江苏张渚园田,砾岩时代为晚二叠世晚期之初。此砾岩的出现说明本区龙潭组沉积之后有一短期侵蚀,并代表长兴组沉积的开始。因此长兴组沉积在各地不同,应是一穿时的地层单位。它始于晚二叠世早期之末至晚二叠世末。并根据岩相分析结果认为本区长兴组是一个由北东向南西展布的浅海台地到台前凹陷的低能海进沉积环境。
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| 关 键 词： | 长兴组底部砾岩 |
THE CHRONOSTRATIGRAPHY AND ITS SIGNIFICANCE OF THE BOTTOM CONGLOMERATE OF THE CHANGXING FORMATION AT THE BORDERING REGION OF JIANGSU, ZHEJIANG AND ANHUI PROVINCES |
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| Authors: | Yao Lunqi |
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| Institution: | Yao Lunqi Department of Marine Geologg,Tongji university |
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| Abstract: | The Changxing Formation of this region distributes mainly in Wuxi and Suzhou of southern Jiangsu Province; Meishan, Changxing of northern Zhejiang Province and Guangde of southern Anhui Province. A conglomerate bed (about 10-30 cm in thickness) exists at the bottom of the Changxing Formation in this region. Fossil-conodonts are contained in the calcareous cement. In Meishan (the ZK 273 well), Neogondolella orientalis is found in the conglomerate, and its geologic time may be the end of the early Late Permian. However, in Dushan (in Anhui Province) and Lishan (in Jiangsu Province), Neogondolella subcarinata and N. changxingesis are found in the conglomerate, and therefore its geologic time may be the beginning of late Late Permian. In conclusion, the occurrence of this conglomerate bed indicates that there was a short erosion period after the deposition of Lungtan Formation and then at different times, deposition of Changxing Formation began in different places, so that it is a diachronous stratigraphic unit from the end of the early Late Permian to the late Late Permian. It was deposited in a lower energy environment of transgression in the sublittoral platform to fore depression of platform from northeast to southwest. |
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| Keywords: | A conglomerate bed at the bottom of the Changxing Formation |
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