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In this paper a fracture zone caused by Aug. 11, 1931 Fuyun earthquake in Xinjiang province is detailly described, and the seismogenic structure and its recent tectonic movement are discussed.This seismic fracture zone has developed superimposedly on the NNW-trending Kok-tohai-Ertai fault, its southern end is beyond the old fracture. The full length of this zone is 170 km. General trend is N342°W. The fault plane dips to north-west at an angle of 70°. The occurence of seismogenic fault, mountain ridges... In this paper a fracture zone caused by Aug. 11, 1931 Fuyun earthquake in Xinjiang province is detailly described, and the seismogenic structure and its recent tectonic movement are discussed.This seismic fracture zone has developed superimposedly on the NNW-trending Kok-tohai-Ertai fault, its southern end is beyond the old fracture. The full length of this zone is 170 km. General trend is N342°W. The fault plane dips to north-west at an angle of 70°. The occurence of seismogenic fault, mountain ridges and ravines show that the movement is mainly horizontal with right-lateral wrench.The great Fuyun earthquake of 8.0 magnitude is an appearance of the recent movement along the Koktohai-Ertai fault, and this movement has a clearly inherit nature in terms of the regional stress state, fracture mechanism and pattern movement. 本文对1931年8月11日富蕴8.0级地震造成的地震断裂带作了较详细的叙述,探讨了发震构造及其新构造运动特征。地震断裂带是在北北西向的可可托海-二台断裂的基础上发展的,南端已超出老断裂范围。全长170公里,总体走向北西342°,断裂面多向北东倾斜,倾角70°左右。从地震断裂的组合形式及山脊、冲沟错动情况,显示出水平运动为主的右旋扭动特征。富蕴8.0级大地震是可可托海-二台断裂新活动的体现,无论在区域受力状况,断裂力学性质和运动方式等方面,都具有强裂的继承性活动特征。 The 1°/1° free-air anomaly and bouguer anomaly of the Chinese continent can be briefly outlined by 104°E as a border line separating into the eastern and the western parts, distinctly different in anomaly features. The anomaly change of the former is gentle with a NNE strike of linear anomaly, while the latter's is intensive with a NWW strike of linear anomaly. The further subdivision of Chinese continent gives four anomaly regions, the Eastern, the Central, the Xinjiang and the Qinghai-Xizang, they vary... The 1°/1° free-air anomaly and bouguer anomaly of the Chinese continent can be briefly outlined by 104°E as a border line separating into the eastern and the western parts, distinctly different in anomaly features. The anomaly change of the former is gentle with a NNE strike of linear anomaly, while the latter's is intensive with a NWW strike of linear anomaly. The further subdivision of Chinese continent gives four anomaly regions, the Eastern, the Central, the Xinjiang and the Qinghai-Xizang, they vary obviously in nature. We discussed the relationships between the regional gravity field and tectonics, isostasy and seismicity. It is suggested that the linear anomalies of the Eastern part reflect mainly the structural system of NNE strike but the Western part reflect the structural system of NWW strike. The Bouguer anomaly gradient zones are coincident with the fault belts between fault blocks, and the Chinese continental crust is principally in an isostatic state on a large scale. Therefore it can be assumed that most of earthquakes would take place along the gravity gradient zones. 中国大陆1°×1°空间重力异常和布格重力异常大体以东经104°线为界分为东、西绝然不同的两部分,东部异常变化平缓,线性异常的走向以北北东向为主,西部异常变化急剧,线性异常的走向以北西西向为主,进而还可分成异常特征明显不同的东部、中部、新疆、青藏四大区。文章初步讨论了中国大陆区域重力场与大地构造,地壳均衡和地震活动的关系,认为中国东部线性异常主要反映了北北东向新华夏构造体系,中国西部线性异常主要反映了北西西向西域构造体系,布格重力异常梯度带大都对应断块间的断裂带;布格重力异常和地形高程基本上呈负相关, 中国大陆地壳在大范围内基本处于均衡状态;地震大都发生在重力梯度带上。 On the basis of the measured ground data ten free air gravity maps of China have been constructed from mean free air values in square areas of 1°×1° to 10°×10° using average filter to eliminate successively the shorter wavelengths. These results indicate a great difference between East China and West China in the anomaly configuration: the anomaly value changes are gently in the East and sharply in the West: the short wavelength anomalies trend in a NE direction in the East and in NW in the West, whereas the... On the basis of the measured ground data ten free air gravity maps of China have been constructed from mean free air values in square areas of 1°×1° to 10°×10° using average filter to eliminate successively the shorter wavelengths. These results indicate a great difference between East China and West China in the anomaly configuration: the anomaly value changes are gently in the East and sharply in the West: the short wavelength anomalies trend in a NE direction in the East and in NW in the West, whereas the long wavelength anomalies trend in a NS direction in the East and in EW in the West. In addition, there are four NW disturbance zones cutting across the NE linear anomalies in the East. From the map 1 (1°×1°) can be seen that in the East there exist two prominent nearly parallel positive anomaly zones, one of which extends from the Changbaishan mountains through the Liaoning and Shandong peninsulas into the coastal ranges in the Zhejiang and Fujian provinces, and the other runs from the Dahin-gganling mountains along the Taihangshan mountains through the Qinling mountains into the ranges of western Hubei and Hunan provinces. Between the two zones exist a wide and low gravity anomaly zone associated with the Songliao, North China and Jianghan plains and Hengyang basin. In the West, the anomaly configurations are very complex and have the same NW direction as the positive linear anomalies over the Qilianshan mountains, the eastern Tianshan and the Altayshan. On the map 2 (3°×3°) are shown the high-amplitude positive anomalies for almost all the mountain regions and the low-amplitude positive or negative anomalies for all the plains and plateaus, whereas the interior basins always correspond to the large high-amplitude negative anomalies. On the map 3 (5°×5°) can be found five dominant large anomalies for the China continent: the positive from 110°E to the east, the negative over the Sichuan basin and Ordos plateau, the positive over the Qinghai and Xizang region, the negative over the Neimon-ggol and Xinjiang Autonomous regions. Besides, a great negative anomaly appears in the eastern Xizang. As shown on the maps 4 and 5 (7°×7° and 9°× 9°), the direction of the main linear anomalies turns into a normal NS one in East China and EW in the West. It is suggested that the short wavelength anomalies (1°×1°) associated with the tectonic features are produced due to successive tectonic movements causing the non-homogenous mass distribution in the lithosphere. The moderate wavelength anomalies (3°×3° and 5°×5°) resulted from the broad bent of the lithosphere caused by the current stress from plate motions. Probably, the long-wavelength anomalies (7°×7° and 9°×9°) are related to the mantle deep-seated mass inhomogeneity, except the effect of the plate motions. The relation of the above-stated phenomena to the tectonic framework, isostasy, seismicity as well as the possible geodynamical process are also discussed. 本文利用地面实测的重力资料计算并构制了从1°×1°到10°×10°平均的中国大陆自由空气重力异常图,并对这套图中所反映出来的基本事实进行了分析和解释,且就这些基本事实与大地构造、地壳均衡、地震活动的关系及其可能的地球动力学过程进行了讨论。
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