四川岷江断裂带北段的新活动、岷山断块的隆起及其与地震活动的关系
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摘要
岷山断块由岷江断裂和虎牙断裂自西向东的推覆逆掩运动所形成 ,处于我国南北地震带的中段。受区域NWW向主压应力场的控制 ,岷江断裂带第四纪以来表现为明显的推覆逆掩运动并具有一定的左旋走滑分量 ,岷山断块则处于强烈的隆起抬升状态。航片解译及野外地质考察结果表明 ,岷江断裂带由数条次级断裂呈羽列组合而成 ,其中尕米寺 -川盘右阶羽列区的羽列距达3km ,控制了低序次的地震破裂单元。第四纪地貌发育过程及断错地貌研究结果表明 ,岷江断裂晚第四纪以来的平均垂直滑动速率为 0 37～ 0 53mm/a ,水平位错量与垂直位错量大致相当 ;岷山断块第四纪以来的平均隆起速率为 1 5mm/a左右。地震活动特征表明 ,该地区 6级以上强震丛集于强烈活动的断块边界断裂上 ,中强地震及小震发生在新构造隆起区及近东西向断裂带上 ,与断裂的活动性质具有密切的成因联系。
Located at the mid section of the north south seismic zone in China, the Minshan block was resulted from the reverse and over thrust movement of the Minjiang fault and the Huya fault from west to east. Under the background of a regional main compressive stress field with NWW direction, the Minjiang fault shows an obvious reverse and overthrust movement with some sinistrogynic slip components, while the Minshan block has strongly uplifted since Quaternary. The aerial photo interpretation and field survery on geology and seismology indicate that the Mingjiang blook is composed of several secondary faults with echelon pattern, among them, the row distance of Gamisi Chuanpan dextral echelon part is 3 km, which perhaps controls the secondary seismic rupture unit. Research by the geological landform formation history and rupture landform shows that the average vertical slip rate of the Minjiang fault is 0.37～0.53 mm/a, the horizontal slip amount is similar to the vertical slip amount since late Quaternary, the average lift rate of Minshan Block is 1.5 mm/a since Quaternary. It is suggested that M ≥6.0 earthquakes occurred mainly on the border faults of the strong blocks, while middle and small earthquakes often took place on the faults with nearly east west direction and new tectonic lift, which are associated with the active features of these faults.
Located at the mid section of the north south seismic zone in China, the Minshan block was resulted from the reverse and over thrust movement of the Minjiang fault and the Huya fault from west to east. Under the background of a regional main compressive stress field with NWW direction, the Minjiang fault shows an obvious reverse and overthrust movement with some sinistrogynic slip components, while the Minshan block has strongly uplifted since Quaternary. The aerial photo interpretation and field survery on geology and seismology indicate that the Mingjiang blook is composed of several secondary faults with echelon pattern, among them, the row distance of Gamisi Chuanpan dextral echelon part is 3 km, which perhaps controls the secondary seismic rupture unit. Research by the geological landform formation history and rupture landform shows that the average vertical slip rate of the Minjiang fault is 0.37～0.53 mm/a, the horizontal slip amount is similar to the vertical slip amount since late Quaternary, the average lift rate of Minshan Block is 1.5 mm/a since Quaternary. It is suggested that M ≥6.0 earthquakes occurred mainly on the border faults of the strong blocks, while middle and small earthquakes often took place on the faults with nearly east west direction and new tectonic lift, which are associated with the active features of these faults.
引文
① 四川省地质矿产局 ,1995,1/5万漳腊幅、黄胜关幅区域地质调查报告
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邓起东 ,于贵华 ,叶文华 .1992 .地震地表破裂参数与震级关系研究 .见 :邓起东主编 .活动断裂研究理论与应用
(2 ) .北京 :地震出版社 .2 4 7～ 2 6 4 .
邓起东 ,陈社发 ,赵小麟 .1994 .龙门山及其邻区的构造地震活动及动力学 .地震地质 ,16 (4 ) :389～ 4 0 3.
马杏垣主编 .1989.中国岩石圈动力学地图集 .北京 :中国地图出版社 .16 .
钱洪 ,马声浩 ,龚宇 .1995.关于岷江断裂若干问题的讨论 .中国地震 ,11(2 ) :140～ 146 .
杨景春 ,邓天岗 ,王元海 ,等 .1979.岷江上游地区第四纪构造应力状态及其与地震的关系 .地震地质 ,1(3) :6 8～ 75.
赵小麟 ,邓起东 ,陈社发 .1994 .岷山隆起的构造地貌学研究 .地震地质 ,16 (4 ) :4 2 9～ 4 39.
BarkaAA ,KKadinsky Cade.1998.Strike -slipfaultgeometryinTurkeyanditsinfluenceonearthquakeactivity .
Tectonics ,17(3) :141～ 16 8.
CarverGA ,McCalpinJP .1996 .PaleoseismologyofcompressionalTectonicEnviroments .EditedbyJamesP ,
Mdalpin .Paleoseismology .SanDiego ,California :AcademicPress ,Inc .183～ 2 70 .
CroneAJ ,MachetteM .1984 .SurfacefaultingaccompanyingtheBorahpeakearthquake ,CentralIdaho .Geology ,12 :149～ 158.
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