中国地质
中國地質
중국지질
CHINESE GEOLOGY
2014年
5期
1464-1475
,共12页
闵刚%程建华%尹秉喜%蔡学林%夏时斌
閔剛%程建華%尹秉喜%蔡學林%夏時斌
민강%정건화%윤병희%채학림%하시빈
宁南弧形构造带%大地电磁探测%电性结构%壳内低阻层%古隆起%滑脱面
寧南弧形構造帶%大地電磁探測%電性結構%殼內低阻層%古隆起%滑脫麵
저남호형구조대%대지전자탐측%전성결구%각내저조층%고륭기%활탈면
Southern Ningxia arc structure%MT method%electrical structure%shell low resistance layer%palaeohigh%detachment layer
提利用大地电磁探测方法在宁南弧形构造带内蒙古乱井-甘肃大沟段进行了中上地壳电性结构特征研究,通过二维反演获得了研究区的电性结构模型,模型清楚揭示出了该区典型的电性结构特征:(1)中上地壳电性结构整体表现为“碎块状”的构造特征,其中走廊构造带总体表现为相对低阻,北祁连碰撞造山带总体表现为相对高阻;(2)海原地震震源区的震源断裂所反映的低阻带构造样式既不像走滑断裂那样陡峭,也不像逆冲断裂那样平缓,而是兼具走滑与逆冲断裂带的双重特征;(3)研究区壳内低阻层呈现不连续分布,总体表现为南深北浅的构造样式,一般都终止于高阻地块边缘或与逆冲推覆构造的滑脱面相交汇处;(4)清水河裂褶带内发育的高阻地块可能为晚古生代或早中生代发育在元古宙基底上的古隆起,为该区燕山期构造运动提供了深部大地电磁资料证据。
提利用大地電磁探測方法在寧南弧形構造帶內矇古亂井-甘肅大溝段進行瞭中上地殼電性結構特徵研究,通過二維反縯穫得瞭研究區的電性結構模型,模型清楚揭示齣瞭該區典型的電性結構特徵:(1)中上地殼電性結構整體錶現為“碎塊狀”的構造特徵,其中走廊構造帶總體錶現為相對低阻,北祁連踫撞造山帶總體錶現為相對高阻;(2)海原地震震源區的震源斷裂所反映的低阻帶構造樣式既不像走滑斷裂那樣陡峭,也不像逆遲斷裂那樣平緩,而是兼具走滑與逆遲斷裂帶的雙重特徵;(3)研究區殼內低阻層呈現不連續分佈,總體錶現為南深北淺的構造樣式,一般都終止于高阻地塊邊緣或與逆遲推覆構造的滑脫麵相交彙處;(4)清水河裂褶帶內髮育的高阻地塊可能為晚古生代或早中生代髮育在元古宙基底上的古隆起,為該區燕山期構造運動提供瞭深部大地電磁資料證據。
제이용대지전자탐측방법재저남호형구조대내몽고란정-감숙대구단진행료중상지각전성결구특정연구,통과이유반연획득료연구구적전성결구모형,모형청초게시출료해구전형적전성결구특정:(1)중상지각전성결구정체표현위“쇄괴상”적구조특정,기중주랑구조대총체표현위상대저조,북기련팽당조산대총체표현위상대고조;(2)해원지진진원구적진원단렬소반영적저조대구조양식기불상주활단렬나양두초,야불상역충단렬나양평완,이시겸구주활여역충단렬대적쌍중특정;(3)연구구각내저조층정현불련속분포,총체표현위남심북천적구조양식,일반도종지우고조지괴변연혹여역충추복구조적활탈면상교회처;(4)청수하렬습대내발육적고조지괴가능위만고생대혹조중생대발육재원고주기저상적고륭기,위해구연산기구조운동제공료심부대지전자자료증거。
In order to study the conductivity characteristics of Dagou-Luanjing middle and upper crust, the authors carried out magnetotelluric sounding work in the study area, and obtained the electrical structure model by the two-dimensional inversion method, which clearly reveals the typical electrical structure of Dagou-Luanjing: (1) The middle and upper crust shows the"chunky"structural style totally, and the authors infer that the conductivity of the corridor structure belt is relatively lower whereas the conductivity of the Qilian orogenic belt is relatively higher;(2) The low-resistivity zone caused by focal fracture of Haiyuan earthquake is neither steep like the strike-slip fault nor gentle like the thrust belt, but has both strike-slip and thrust characteristics;(3) The low-impedance and high-conductivity layers in the mid-upper crust of the study area intermittently exist, and show the structural style of deeper in the south and shallower in the north; it can also be inferred that these low-impedance and high-conductivity layers always reach their termination at the edge of the high impedance plots, or intersect the detachment layer under the thrust nappes; (4) A high resistance block exists in Qingshui River depression basin, which is likely to be an“island chain”paleouplift that was developed on the basin basement in Late Paleozoic and Early Mesozoic period,thus providing evidence for the tectonic movement of Yanshanian.