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新疆阿尔泰山富蕴断裂带几何学与地貌学特征研究
张之武
Subtype硕士
Thesis Advisor刘小汉
2009-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士研究生
Degree Discipline构造地质学
Keyword活动断层  断层分段  右旋走滑  滑动速率  拉分盆地  滑脱面深度  晚第四纪  富蕴断裂带  阿尔泰山
Call NumberS000023
Abstract

富蕴断裂带位于阿尔泰山南侧,横切阿尔泰山褶皱带南缘及额尔齐斯深断裂,是一条长180 km呈北北西向展布的右旋走滑断裂带。1931年M8.0级富蕴地震形成地表破裂带的地貌特征,经过70多年后仍保存良好。小型的地震鼓包、地震凹槽、断层陡坎、错断山脊、错断冲沟等一系列与走滑活动相关的构造地貌特征,在整个的地表破裂带均有分布,使其成为研究走滑类活动断裂的天然实验室。论文在高分辨率遥感图像、后差分GPS测量技术和数字高程模型分析的基础上,结合野外实地构造地貌测量,对沿富蕴断裂带的构造地貌、几何特征、沿断裂带发育拉分盆地、系统错断水系相关特征进行了分析研究。研究结果表明:根据1931年富蕴M8.0级地震形成的地表破裂带几何学和地貌学特征以及错断量的分布特征,可将其划分为五个一级段:从北向南依次为S1,S2,S3,S4,S5,各段长度15~47 km不等;另外,这些一级段还可进一步划分出若干二级亚段,如S3进一步分为南、中、北三段,各段长度在几公里到十几公里之间。分段结果与水平位移分布显示出良好的一致性,每段起始、结束位移小,中间明显偏大。错断量的分布特征在分段断裂边界多出现突变,推测1931年M8.0级富蕴地震中,主震之后可能伴有若干次亚事件发生。此外,根据卡拉先格尔地区地表破裂带分布特征与前人的研究资料分析,挤出式的断裂构造机制能较好的解释这一现象。利用DGPS技术手段结合野外实地考察资料,对发育于富蕴断裂带的小型拉分盆地进行初步研究后得到如下结论:该拉分盆地是最近大地震形成的产物;公式ⅱ中R取值应该为7~8m,估算该拉分盆地滑脱面深度大约为40m。测量得到的DGPS精度较高,由于限制因素存在,因此该深度值仅为一半定量参考值。应用构造-气候旋回概念建立时间标尺,利用河流阶地与错断水系相结合方法,借助于遥感影像数据以及有关冰川学资料,大体估算出断裂的滑动速率范围。沿富蕴断裂带分布的水系大致可以划分为6个级别:1931年地震形成的冲沟;90m左右断距的恰尔沟三级支流错断水系,可能形成时间为末次冰期Ⅲ阶段末期,约20 ka;150 m左右断距的恰尔沟二级支流错断水系,可能形成时间为末次冰期Ⅰ阶段末期,约120 ka;500 m左右断距的恰尔沟一级支流错断水系,可能形成于该地区冰川广泛消融的倒数第2次冰期的Ⅱ阶段末期,约为250 ka;1500 m左右断距的恰尔沟、水磨沟、白杨沟、乌铁布克河、卡布尔特河等错断水系,可能形成于倒数第3次冰期Ⅱ阶段末期,约为360 ka;2000 m以上断距的额尔齐斯河与乌伦古河错断水系。根据水系断距,及相关年代学数据估算,得出富蕴断裂带晚第四纪以来平均右旋走滑速率为1.46~4.99 mm/a。总之,富蕴断裂带是中亚大陆内部重要的活动断裂带,为研究走滑构造地貌特征与几何特征提供了宝贵的素材,是走滑断裂带微构造地貌研究的天然实验室。

Other Abstract

The Fuyun Fault Zone, a NNW-trending right-lateral strike-slip fault, is located in the south of the Altay Mountains, Northeastern Xinjiang, China. Geomorphologic features, such as offset streams, fluvial fans, terraces, pull-apart basins and pressure ridges are well developed along the fault zone. These typical geomorphologic features related to strike-slip fault are resulted from long term geomorphologic growth and the dry and cold climate as well as the little humans’ activities in these mountain-regions. The surface rupture associated with 1931 Fuyun M 8.0 earthquake extends about 160 km, and dominant style of faulting is right-lateral strike-slip. The rupture zone can be divided into five first-order segments; S-1, 2, 3, 4, and 5 segments from north to south, whose length are between 15 and 47 km, mainly according to the distribution of strands and fault displacements. In addition, some segments also can be further divided into second-order segments. For example, the S3 can be divided into the southern, central, and northern sub-segments with a few kilometers to more than ten kilometers in length. The distribution of the horizontal displacement along the fault shows a good and obvious consistency with each segment. Usually at the end of each segment, the displacement is small, but at the middle of each segment, it is huge. The distribution of displacement along the fault changes suddenly around boundaries of segments. So we infer that the mainshock may occur with a number of sub-events during the 1931 Fuyun M 8.0 earthquake. According to the DGPS method as well as field observations, we study a single small pull-apart basin appearing along the Fuyun Fault rupture and calculate its detachment’s depth. We infer the basin was formed by the last event and the dextral offset is about 7 ~ 8 m. Based on the model inferred and the 7 ~ 8 m displacement, we finally estimate the detachment’s depth of the pull-apart, which is about 40 meters. However, considering the existence of the constraints, this result may be not a precise estimation. Based on the analyses of high-resolution satellite images (Landsat TM, ASTER VNIR, ASTER DEM and IKONOS data) as well as field observations, we document the Late Quaternary stream offsets along the Fuyun Fault Zone. The result shows that offset streams occurred along the Fuyun Fault Zone. And they can be classified into six groups: 8 m, 90 m, 150 m, 500 m, 1500 m, and more than 2000 m offsets. We inferred that these different scale stream offsets are likely formed in ca 1931, 20 ka, 120 ka, 250 ka, 360 ka and late Miocene, respectively, based on analyses of glacial data in the whole Altay Mountains. Finally, we estimate that a long-term slip rate ranges from 1.46 mm/a to 4.99 mm/a since the Late Pleistocene (ca 360 ka B P), which is a little higher than the slip rate (1 mm/a) of strike-slip faults in the Mongolian Altay Mountains and that one measured from the geodetic measurements (0.86~2.00 mm/a), but it is close to the result estimated from the geologic features (4±2 mm/a). In summary, the remote sensing method plays an important method in the active fault research. the Fuyun Fault is an important active fault in the Altay Mountains, and also an important active fault in the central Asia.

Department大陆碰撞与高原隆升重点实验室
Subject Area地质学
MOST Discipline Catalogue理学::地质学
Pages52 页
Language中文
Document Type学位论文
Identifierhttp://ir.itpcas.ac.cn/handle/131C11/1216
Collection图书馆
Recommended Citation
GB/T 7714
张之武. 新疆阿尔泰山富蕴断裂带几何学与地貌学特征研究[D]. 北京. 中国科学院研究生院,2009.
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