【摘要】：小江斷裂帶南段位于近SN向的鮮水河-小江斷裂系與NW向的紅河-哀牢山斷裂系的交會(huì)地帶。在遙感影像上,小江斷裂帶南段線狀特征清楚,且連續(xù)分布,表現(xiàn)為1條貫通的、單一的斷裂構(gòu)造,全長(zhǎng)約70km,總體走向N20°E左右,中間呈略向E凸出的弧形。在龍?zhí)洞鍍刹砗右粠?沿著該斷裂段存在比較典型的山脊、沖溝同步左旋位錯(cuò)現(xiàn)象。在跨斷塞塘開(kāi)挖的探槽剖面上,斷裂分布狀況、斷錯(cuò)地層的沉積學(xué)特征、產(chǎn)狀變化以及初步年代測(cè)試結(jié)果揭示了3次明顯斷錯(cuò)地表的古地震事件,顯示了小江斷裂帶南段具有重復(fù)孕育和發(fā)生強(qiáng)震的能力。利用Trimble 5800 GPS實(shí)時(shí)差分測(cè)量系統(tǒng),對(duì)兩岔河地區(qū)存在典型同步位錯(cuò)特征的2條沖溝及其它們中間的臺(tái)地進(jìn)行了精細(xì)測(cè)量,位錯(cuò)量為(18.3±0.5)m;T_2階地面是斷裂西盤(pán)2條沖溝之間及其鄰近地帶的最高層狀地貌面,通過(guò)不同深度年代數(shù)據(jù)的線性回歸分析,該地貌面停止接受沉積的時(shí)代約為2606a BP。根據(jù)地質(zhì)方法獲得了小江斷裂帶南段全新世左旋走滑速率為(7.02±0.20)mm/a,與利用GPS數(shù)據(jù)獲得的結(jié)果有著較好的一致性。對(duì)小江斷裂帶南段活動(dòng)性和滑動(dòng)速率的初步研究結(jié)果表明,在滇東南地區(qū)不存在川滇塊體向S或SSE方向滑移被曲江斷裂和石屏-建水?dāng)嗔褦D壓變形吸收、而使得小江斷裂帶南段左旋走滑速率大幅度減小的現(xiàn)象,該斷裂段是1條活動(dòng)性明顯的全新世斷裂。這些初步認(rèn)識(shí)為小江斷裂帶南段的未來(lái)地震危險(xiǎn)性評(píng)價(jià)以及川滇地區(qū)的地震構(gòu)造模型建立和檢驗(yàn)提供了可以借鑒的基礎(chǔ)地質(zhì)資料。
[Abstract]:The southern section of the Xiaojiang fault zone is located in the intersection zone between the Xianshuihe-Xiaojiang fault system near the SN direction and the Honghe-Ailaoshan fault system in the NW direction. In remote sensing images, the southern section of the Xiaojiang fault zone has clear linear features and continuous distribution, showing a single fault structure with a total length of about 70 km, with an overall strike of about N20 擄E, and a slightly protruding arc in the middle. Along the Liangcha River of Longtan Village, there are typical ridges along this fault section and synchronous left-lateral dislocation phenomenon in gullies. The distribution of faults, the sedimentary characteristics of faulted strata, the changes of occurrence and the preliminary dating results reveal three paleoearthquake events on the surface of obvious fault on the section of the exploration channel excavated across the faulted seawall. It shows that the south section of Xiaojiang fault zone has the ability of repeated preparation and strong earthquake. Using Trimble 5800 GPS real time differential measurement system, two gullies with typical synchronous dislocation characteristics and other platforms in the middle of Liangchahe area were carefully measured. The dislocation amount was (18.3 鹵0.5) m. The T _ 2th surface is the highest stratified geomorphologic surface between the two gullies in the western rim of the fault and its adjacent zone. By linear regression analysis of the age data of different depths, the age at which the geomorphologic surface ceased to accept deposition was about 2606a BP.. According to the geological method, the left-lateral strike-slip rate of the southern section of the Xiaojiang fault zone in Holocene is (7.02 鹵0.20) mm/a, which is in good agreement with the results obtained from the GPS data. The preliminary study on the activity and slip rate of the southern section of the Xiaojiang fault zone shows that there is no S or SSE direction slip of the Sichuan-Yunnan block in the southeast of Yunnan province, which is absorbed by the compression deformation of Qujiang fault and Shiping-Jianshui fault. However, the left-lateral strike-slip rate of the southern section of the Xiaojiang fault zone is greatly reduced. The fault segment is an active Holocene fault. These preliminary understandings provide basic geological data for the future seismic risk assessment in the southern section of the Xiaojiang fault zone and for the establishment and verification of seismic structural models in Sichuan-Yunnan region.
【作者單位】： 中國(guó)地震局地質(zhì)研究所;中國(guó)地質(zhì)大學(xué)(北京) 地球科學(xué)與資源學(xué)院;陜西省地震局;
【基金】：國(guó)家自然科學(xué)基金(41372219) 地震行業(yè)科研專(zhuān)項(xiàng)(201108001)共同資助
【分類(lèi)號(hào)】：P315.2

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