小江—奠边府断裂活动性研究
发布时间：2018-08-20 17:38
【摘要】：小江断裂和奠边府断裂均为深切地壳的重要块体边界,GPS观测显示出青藏高原物质受塔里木、阿拉善、四川地块阻挡,被向东挤出并发生顺时针转向,之后以二者为东-东南边界跨红河断裂带连续变形,对南北地震带南段的研究也将注意力投向印支地区,但侧向挤出和南北地震带边界的认识尚未统一。深入探讨小江断裂和奠边府断裂之间的联系,对促进中国大陆强震活动规律和地壳运动研究的完整性、全面性有重要意义。 以收集、分析、消化国内外前人研究资料和成果为主要方法从大地构造、新构造运动背景、断裂演化历史和深部介质特性,研究了小江和奠边府断裂存在的联系；为了提高地震活动性分析数据精度,在研究区(19°～27°N,101°～104°E)1900年至2014年地震目录和双差定位方法重定位2000年1月至2014年7月地震得到3702个结果基础上,使用GIS平台三维可视化和筛选与断裂带有关地震,分析活动时空分布；利用地壳应力资料和震源机制解用于研究区域和断裂应力状态、产状,并对比最新的地壳形变成果。形成以下认识： 1.小江断裂、奠边府断裂两侧块体性质存在明显差异。印支地块内印支古陆核和掸泰古陆核具有前寒武纪结晶基底,而华南地块是早古生代加里东时期形成的古褶皱系,地壳密度大,地磁和重力异常变化较弱,具有整体稳定的特点。相对软弱的川滇地块内部地磁异常和重力异常存在正负相间的现象。思茅一兰坪地块延续了川滇块体低密度趋势。 2.新构造运动以来小江和奠边府断裂,通过大规模的左旋走滑控制区域块体间差异运动,拥有相似大震孕育模式：6级以上大震后活动减弱,而后爆发6级以上大震。奠边府平静期更长,可能爆发更大地震。研究区1970年至1983年莱州地震期间为6级以上地震高发期,之后20多年地震活动强度和震级都偏低,2000年至2014年没有M≥5.0级地震。小江断裂带北端震源深度连续分布在0km～60km,中南段一直到奠边府断裂带集中在33km和lOkm深度处。小震也有类似北深南浅现象。震源机制解数据反映区内地震走滑为主,地壳应力近水平。小江断裂带附近主压应力集中在NW-SE向,奠边府断裂在NNW-SSE,主压应力近水平,断层破裂面陡立。 3.研究区内断层以走滑活动为主。地壳应力受到小江断裂、奠边府断裂约束时,根据应力大小和与断裂夹角的不同,表现出逆断活动或应力矢量方向突变现象。参考各个稳定地块的GPS观测反映形变矢量遇到华南地块、昆嵩地块时发生转向。 综上,小江断裂和奠边府断裂分隔了强弱块体,是地球物理场、地壳应力和地壳形变的突变带,地震活动具有相似性,将他们作为青藏高原侧向挤出和南北地震带边界较为合适。 限于资料的不足,地震数据有限,目前所做的研究还有许多方面可以改进和深入。
[Abstract]:Both the Xiaojiang fault and the Dianbifu fault are important block boundaries of deep crust. GPS observations show that the material of the Qinghai-Tibet Plateau is blocked by the Tarim, Alashan, and Sichuan landmasses, squeezed eastward and turned clockwise. After that, the study on the southern segment of the north-south seismic belt is also focused on the Indosinian region, but the understanding of lateral extrusion and the boundary of the north-south seismic belt has not been unified. It is of great significance to probe into the relationship between Xiaojiang fault and Dianbianfu fault in order to promote the regularity of strong earthquake activity and the integrality of crustal movement in the mainland of China. By collecting, analyzing and digesting the previous research data and achievements at home and abroad, the relationship between Xiaojiang fault and Dianbianfu fault is studied from geotectonic, neotectonic background, history of fault evolution and characteristics of deep medium. In order to improve the accuracy of seismicity analysis data, based on the results of seismic catalogs from 1900 to 2014 in the study area (19 掳~ 27 掳N ~ + 101 掳~ 104 掳E) and the relocation of earthquakes from January 2000 to July 2014, 3702 results were obtained. GIS platform is used to visualize and screen earthquakes related to fault zones and to analyze the temporal and spatial distribution of activity. The crustal stress data and focal mechanism solution are used to study the regional and fault stress states and occurrence, and the latest crustal deformation results are compared. Form the following understanding: 1. There are obvious differences in block properties between Xiaojiang fault and Dianbifu fault. Indosinian paleo-continental nucleus and Shantaigu continental nucleus in Indosinian block have Precambrian crystalline basement, while South China block is a paleofold system formed in early Paleozoic Caledonian period, with high crustal density and weak variation of geomagnetic and gravity anomalies. It has the characteristics of overall stability. There is a positive and negative phase between geomagnetic anomaly and gravity anomaly in the relatively weak Sichuan-Yunnan block. The Simao-Lanping block continues the low density trend of Sichuan-Yunnan block. 2. Since the neotectonic movement, the Xiaojiang and Dianbianfu faults, through large-scale left-lateral strike-slip control regional differential movement between blocks, have similar strong earthquake preparation mode after the strong earthquake of M 鈮，
本文编号：2194454
[Abstract]:Both the Xiaojiang fault and the Dianbifu fault are important block boundaries of deep crust. GPS observations show that the material of the Qinghai-Tibet Plateau is blocked by the Tarim, Alashan, and Sichuan landmasses, squeezed eastward and turned clockwise. After that, the study on the southern segment of the north-south seismic belt is also focused on the Indosinian region, but the understanding of lateral extrusion and the boundary of the north-south seismic belt has not been unified. It is of great significance to probe into the relationship between Xiaojiang fault and Dianbianfu fault in order to promote the regularity of strong earthquake activity and the integrality of crustal movement in the mainland of China. By collecting, analyzing and digesting the previous research data and achievements at home and abroad, the relationship between Xiaojiang fault and Dianbianfu fault is studied from geotectonic, neotectonic background, history of fault evolution and characteristics of deep medium. In order to improve the accuracy of seismicity analysis data, based on the results of seismic catalogs from 1900 to 2014 in the study area (19 掳~ 27 掳N ~ + 101 掳~ 104 掳E) and the relocation of earthquakes from January 2000 to July 2014, 3702 results were obtained. GIS platform is used to visualize and screen earthquakes related to fault zones and to analyze the temporal and spatial distribution of activity. The crustal stress data and focal mechanism solution are used to study the regional and fault stress states and occurrence, and the latest crustal deformation results are compared. Form the following understanding: 1. There are obvious differences in block properties between Xiaojiang fault and Dianbifu fault. Indosinian paleo-continental nucleus and Shantaigu continental nucleus in Indosinian block have Precambrian crystalline basement, while South China block is a paleofold system formed in early Paleozoic Caledonian period, with high crustal density and weak variation of geomagnetic and gravity anomalies. It has the characteristics of overall stability. There is a positive and negative phase between geomagnetic anomaly and gravity anomaly in the relatively weak Sichuan-Yunnan block. The Simao-Lanping block continues the low density trend of Sichuan-Yunnan block. 2. Since the neotectonic movement, the Xiaojiang and Dianbianfu faults, through large-scale left-lateral strike-slip control regional differential movement between blocks, have similar strong earthquake preparation mode after the strong earthquake of M 鈮，
本文编号：2194454
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