【摘要】：小江斷裂和奠邊府斷裂均為深切地殼的重要塊體邊界,GPS觀測顯示出青藏高原物質受塔里木、阿拉善、四川地塊阻擋,被向東擠出并發(fā)生順時針轉向,之后以二者為東-東南邊界跨紅河斷裂帶連續(xù)變形,對南北地震帶南段的研究也將注意力投向印支地區(qū),但側向擠出和南北地震帶邊界的認識尚未統(tǒng)一。深入探討小江斷裂和奠邊府斷裂之間的聯(lián)系,對促進中國大陸強震活動規(guī)律和地殼運動研究的完整性、全面性有重要意義。 以收集、分析、消化國內外前人研究資料和成果為主要方法從大地構造、新構造運動背景、斷裂演化歷史和深部介質特性,研究了小江和奠邊府斷裂存在的聯(lián)系；為了提高地震活動性分析數(shù)據精度,在研究區(qū)(19°～27°N,101°～104°E)1900年至2014年地震目錄和雙差定位方法重定位2000年1月至2014年7月地震得到3702個結果基礎上,使用GIS平臺三維可視化和篩選與斷裂帶有關地震,分析活動時空分布；利用地殼應力資料和震源機制解用于研究區(qū)域和斷裂應力狀態(tài)、產狀,并對比最新的地殼形變成果。形成以下認識： 1.小江斷裂、奠邊府斷裂兩側塊體性質存在明顯差異。印支地塊內印支古陸核和撣泰古陸核具有前寒武紀結晶基底,而華南地塊是早古生代加里東時期形成的古褶皺系,地殼密度大,地磁和重力異常變化較弱,具有整體穩(wěn)定的特點。相對軟弱的川滇地塊內部地磁異常和重力異常存在正負相間的現(xiàn)象。思茅一蘭坪地塊延續(xù)了川滇塊體低密度趨勢。 2.新構造運動以來小江和奠邊府斷裂,通過大規(guī)模的左旋走滑控制區(qū)域塊體間差異運動,擁有相似大震孕育模式：6級以上大震后活動減弱,而后爆發(fā)6級以上大震。奠邊府平靜期更長,可能爆發(fā)更大地震。研究區(qū)1970年至1983年萊州地震期間為6級以上地震高發(fā)期,之后20多年地震活動強度和震級都偏低,2000年至2014年沒有M≥5.0級地震。小江斷裂帶北端震源深度連續(xù)分布在0km～60km,中南段一直到奠邊府斷裂帶集中在33km和lOkm深度處。小震也有類似北深南淺現(xiàn)象。震源機制解數(shù)據反映區(qū)內地震走滑為主,地殼應力近水平。小江斷裂帶附近主壓應力集中在NW-SE向,奠邊府斷裂在NNW-SSE,主壓應力近水平,斷層破裂面陡立。 3.研究區(qū)內斷層以走滑活動為主。地殼應力受到小江斷裂、奠邊府斷裂約束時,根據應力大小和與斷裂夾角的不同,表現(xiàn)出逆斷活動或應力矢量方向突變現(xiàn)象。參考各個穩(wěn)定地塊的GPS觀測反映形變矢量遇到華南地塊、昆嵩地塊時發(fā)生轉向。 綜上,小江斷裂和奠邊府斷裂分隔了強弱塊體,是地球物理場、地殼應力和地殼形變的突變帶,地震活動具有相似性,將他們作為青藏高原側向擠出和南北地震帶邊界較為合適。 限于資料的不足,地震數(shù)據有限,目前所做的研究還有許多方面可以改進和深入。
[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 擄~ 27 擄N ~ + 101 擄~ 104 擄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，

本文編號：2194454