| 内蒙古东部古生代块体碰撞区的大地电磁测深研究——Ⅰ.观测与资料分析 |
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| 引用本文： | 白登海,蒋邦本.内蒙古东部古生代块体碰撞区的大地电磁测深研究——Ⅰ.观测与资料分析[J].地球物理学报,1993,36(3):326-336,T001. |
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| 作者姓名： | 白登海 蒋邦本 |
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| 作者单位： | 1. 中国科学院地球物理研究所北京 100101;
2. 北京大学地球物理系, 北京 100871 |
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| 基金项目： | 国家自然科学基金;北京大学地质系博士点基金联合资助的课题 |
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| 摘 要： | 内蒙古东部地区是古生代古亚洲洋闭合、中朝和西伯利亚块体碰撞区的中东段.本文分析了赤峰-东乌旗长约400km的剖面上12个点的大地电磁（MT）资料,介绍了数据处理方法,讨论了研究区的电性特征.研究区是一个二维性占主要成分的三维结构,受此影响,大多数点的视电阻率曲线含有明显的静态移动和畸变效应,对此采取了静态校正和畸变校正.校正后的视电阻率和相位及感应函数显示出:1.巴林右旗以南和西乌旗以北是两个相对的高阻值区,剖面中部的大兴安岭地区是相对的低阻值区;2.视电阻率曲线在周期大于1000s时普遍呈下降趋势,相应的相位则呈上升趋势,反映了该区上地幔高导层的存在;3.西拉木伦河北侧的早古生代蛇绿混杂岩带和锡林浩特杂岩带表现出横向上强的电性梯级变化.结合地质资料,初步认为上述两个电性梯级带是两个可能的地质分界线,分别对应中朝块体和西伯利亚块体早古生代和晚古生代的缝合带;4.东乌旗-西乌旗之间中地壳有一发育较好的高导层,观测中没有发现贺根山地区具有较深的“根”;5.赤峰-翁牛特旗之间电性存在较大差异,有可能表征了一个较大的断裂或地质界限.
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| 关 键 词： | 内蒙古东部 块体碰撞区 大地电磁测深 静态校正 畸变校正 |
| 收稿时间： | 1992-01-29 |
A MAGNETOTELLURIC STUDY OF THE PALEOZOIC COLLISION ZONE IN THE EAST OF INNER-MONGOLIA:I. OBSERVATIONS AND DATA ANALYSES |
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| BAI DENG-HAI,ZHANG LI,KONG XIANG-RU,JIANG BANG-BEN,GAO WEN.A MAGNETOTELLURIC STUDY OF THE PALEOZOIC COLLISION ZONE IN THE EAST OF INNER-MONGOLIA:I. OBSERVATIONS AND DATA ANALYSES[J].Chinese Journal of Geophysics,1993,36(3):326-336,T001. |
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| Authors: | BAI DENG-HAI ZHANG LI KONG XIANG-RU JIANG BANG-BEN GAO WEN |
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| Institution: | 1. Institute of Geophysics, Academia Sinica, Beijing 100101;
2. Department of Geophysics, Peking University, Beijing 100871 |
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| Abstract: | Magnetotelluric （MT） observations at 12 sites were carried out along a profile of about 400 km long, from Chifeng to Dong Ujimqin Qi in the East of Inner-Mongolia, where is the mid-east part of the Paleo-Asian Ocean collision zone of the Paleozoic time. This paper analyses the characteristics of the observed data and discribes the data processing. Finally, the major electromagnetic features of the area are discussed. The area is mainly a 2D structure with some 3D dimensionality. Affected by the local inhomogeneities, the MT curves for most sites are contaminated by static shifts and distortion effects. For these reasons, static and distortion corrections are employed in data analysis. Correc ted apparent resistivities and impedence phases, as well as induction functions show: 1. Regions northwards from Xi Ujimqin Qi and southwards from Bairin Youqi appear relatively high resistive, while the Great Hinggan volcanic regions in the middle of the profile relatively low resistive. 2. The decline in the apparent resistivities and the rise in the impedence phases for all sites beyond 1000s period maybe indicate the exsistance of the upper mantle conductive layer. 3. Very strong variations in electric features can be seen in the Early Paleozoic ophiolites on the north of Xar Moron River and the Xilinhot complex on the south of Xi Ujimqin Qi. Considering the geological materials, we think preliminarily they symbolize the Early and Late Paleozoic suture zones of the Sino-Ko-rean and Siberian blocks respectively. 4. A well developed conductive layer lies in the mid-crust between Dong Ujimqin Qi and Xi Ujimqin Qi, but no obvious deep "roots" were found in Hegenshan this time. 5. Remarkable changes in electric features between Ongniud Qi and Chifeng may reflect a big fault or geological division. |
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| Keywords: | The East of Inner-Mongolia Collision zone Magnetotelluric Static correction Distortion correcion |
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