| 西藏荣玛地区尼俄玛山下二叠统曲地组沉积特征 |
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| 引用本文： | 陈耀飞,高金汉,王根厚,黄宇飞,孙霄飞,王忠宝.西藏荣玛地区尼俄玛山下二叠统曲地组沉积特征[J].古地理学报,2016,18(1):49-63. |
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| 作者姓名： | 陈耀飞 高金汉 王根厚 黄宇飞 孙霄飞 王忠宝 |
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| 作者单位： | 1.中国地质大学(北京)地球科学与资源学院,北京 100083;2.内蒙古自治区第九地质矿产勘查有限公司,内蒙古锡林浩特 026000 |
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| 基金项目： | Financially supported by the four Geological Maps (No.I45E019011,I45E019012,I45E020011,I45E020012) 1︰50000 Regional Geological and Mineral Survey Project in Rongma Area, Tibet(No.Base[2014]01-029-015) |
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| 摘 要： | 西藏荣玛地区尼俄玛山下二叠统曲地组发育一套重力流沉积组合,根据其岩性、沉积构造和含化石特征等,在该套沉积体系识别出了9种岩石类型、5种岩石组合类型,并分别将其划归内扇主水道-水道间、中扇分支水道-天然堤-水道间、外扇朵叶体-末端水道及深水玄武岩和泥岩4种微相组合类型,以及海底扇和深海盆地2种沉积相类型,证明研究区曲地组属于半深海-深海沉积环境。这一结论与前人认为曲地组属于滨浅海相的认识完全不同,说明南羌塘盆地下二叠统曲地组在区域上存在明显的相变,即西部日土一带的滨浅海沉积向东到改则-尼玛一带逐渐变为半深海-深海沉积;证明南羌塘盆地早二叠世古特提斯洋进入演化成熟期,但羌塘地块从冈瓦纳北缘的裂解、脱离时间在东西向并不一致,东部早于西部;曲地组大套深水黑色泥页岩及砂岩为代表的重力流沉积的广泛发育,说明其具有重要的油气地质意义。
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| 关 键 词： | 岩石类型 岩石组合 曲地组 下二叠统 西藏荣玛地区 |
| 收稿时间： | 10 July 2015 |
Sedimentary characteristics of the Lower Permian Qudi Formation of Ni’ema Mountain in Rongma area,Tibet |
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| Chen Yaofei,Gao Jinhan,Wang Genhou,Huang Yufei,Sun Xiaofei,Wang Zhongbao.Sedimentary characteristics of the Lower Permian Qudi Formation of Ni’ema Mountain in Rongma area,Tibet[J].Journal of Palaeogeography,2016,18(1):49-63. |
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| Authors: | Chen Yaofei Gao Jinhan Wang Genhou Huang Yufei Sun Xiaofei Wang Zhongbao |
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| Institution: | 1. School of Earth Science and Resources, China University of Geosciences(Beijing),Beijing 100083;
2. Inner Mongolia ninth Geology and Mineral Exploration and Development Institute,Xilinhot 026000,Inner Mongolia |
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| Abstract: | A set of gravity flow sediments is found in the Lower Permian Qudi Formation in Ni’ema Mountain of Rongma area,Tibet. According to the lithology,sedimentary structures and fossil records,9 rock types and 5 rock associations can well be identified. These rock types belong to the inner fan,the middle fan, and the outer fan respectively of submarine fan and can be subdivided into the main channel and inter-channel microfacies of inner fan,the branch channel,natural levee and inter-channel microfacies of middle fan,the leafy sand body and ending channel microfacies of outer fan,as well as the deep-sea basalt and mudstone. Therefore,it is fairly concluded that the Qudi Formation in the study area is an abyssal fan formed in a bathyal to abysmal settings. Obviously,this conclusion is different from the previous so called shallow marine Qudi Formation,and it can be illustrated that the sedimentary environment of the Qudi Formation in the Southern Qiangtang Basin is obviously different regionally in the west from in the east direction,which was gradually changed from the shallow marine in Ritu in the west to the abysmal-bathyal in Gaize and Nima in the east. It also shows that the Palaeotethys in the study area was at the mature evolutionary stage in the Early Permian,and the time when Qiangtang block rifted and drifted from the northern margin of Gondwana is earlier in the east than in the west. The discovery of the large set of deep water black gravity flow sediments of the Qudi Formation shows that it has a great significance of petroleum geology. |
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| Keywords: | rock types rock association Qudi Formation Lower Permian Rongma area in Tibet |
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