| 赣东北蛇绿岩带相关地质问题的构造古地理分析 |
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| 引用本文： | 吴浩若.赣东北蛇绿岩带相关地质问题的构造古地理分析[J].古地理学报,2003,5(3):328-342. |
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| 作者姓名： | 吴浩若 |
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| 作者单位： | 中国科学院地质与地球物理研究所 北京100029 |
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| 摘 要： | 对赣东北蛇绿混杂岩带相关地层的时代、沉积相和接触关系等方面认识的重大分歧,导致对华南地质演化史的不同解释。混杂岩的深成岩块体的同位素年龄数据大都在900～1000Ma之间,伴生的火山－沉积岩系（登山群）中却有古生代微体化石发现,但化石的确切年代尚难确定。古地理分析表明,赣东北地区早古生代并不存在“江南古陆”,却有深水的江南海盆。华南晚奥陶世火山碎屑沉积广泛分布,但来源不明,赣东北有可能为当时喷发中心,形成于火山岛弧环境的登山群正好与之匹配。因而,其时代可能为晚奥陶世。志留纪早期江南海盆封闭,扬子地块和华夏地块之间形成加里东褶皱带,赣东北蛇绿岩带为加里东褶皱带和华夏地块之间的接合带。这里扬子地块和华夏地块的距离最近,挤压程度高,抬升幅度大,剥蚀时间长,早古生代沉积不易保存,登山群可能是残留部分。
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| 关 键 词： | 赣东北 蛇绿岩 地质问题 构造古地理分析 晚奥陶世 登山群 |
| 文章编号： | 1671-1505(2003)03-0328-15 |
| 修稿时间： | 2002年12月6日 |
TECTONOPALAEOGEOGRAPHIC ANALYSIS OF THE GEOLOGIC PROBLEMS RELATED TO OPHIOLITIC BELT IN NORTHEASTERN JIANGXI PROVINCE |
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| Wu Haoruo Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing.TECTONOPALAEOGEOGRAPHIC ANALYSIS OF THE GEOLOGIC PROBLEMS RELATED TO OPHIOLITIC BELT IN NORTHEASTERN JIANGXI PROVINCE[J].Journal of Palaeogeography,2003,5(3):328-342. |
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| Authors: | Wu Haoruo Institute of Geology and Geophysics Chinese Academy of Sciences Beijing |
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| Institution: | Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | The different views on the age, lithofacies and contact relationship of the strata related to the ophiolite melange belt in northeastern Jiangxi Province lead to the different explanations on the history of geological evolution of South China. The isotopic ages obtained from igneous blocks of the melange were mostly between 900 and 1 000 Ma. On the other hand, some Paleozoic microfossils were found from a volcanic-sedimentary sequence (Dengshan Group) associated with the ophiolitic belt, but the exact ages of those fossils could not be determined. The palaeogeographic analysis indicates that in the Early Paleozoic there was not a "Jiangnan Paleocontinent", but a deep-water "Jiangnan Basin" in northeastern Jiangxi Province. Late Ordovician pyroclastic deposits are widely spread in South China, but their source is still unclear. Based on the lithofacies palaeogeographic analysis, the eruptive center was probably located in northeastern Jiangxi Province at that time, which just matched with the Dengshan Group formed in the volcanic island-arc environment,implying that it is the Late Ordovician age to the Dengshan Group. In the early Silurian the Jiangnan Basin closed and a Caledonian fold belt was formed between the Yangtze Block and Cathaysian Block. The ophiolitic belt in northeastern Jiangxi Province was a suture between the fold belt and the Cathaysian Block. Here the distance between the two blocks are the smallest in South China and rocks were strongly compressed, resulting in major uplift and stronger erosion. Therefore, Lower Paleozoic was difficult to be preserved in the area, and the Dengshan Group was just their remains. |
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| Keywords: | northeastern Jiangxi ophiolite melange Dengshan Group Late Ordovician tectono-palaeogeographic analysis |
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