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161.
Chai Chizhang 《中国地震研究》2007,21(3):225-235
The paper introduces the steps and methods of multi-approach,multi-level exploration of buried faults in thick Quaternary sediment regions by taking the test exploration of the Yinchuan active fault as example.Based on the comprehensive analyses of previous data,we choose the Xinqushao Village of Xingqing District of Yinchuan City as the test site for the comprehensive exploration.Firstly,we adopted shallow seismic investigation with group intervals of 10m,5m and 1m to gradually trace layer by layer the master fault of the Yinchuan buried fault from a deep depth to a shallow depth where drilling could be used.Then,with composite geological profile drilling,we determined the precise location and dip angle of the fault.The drilling show the buried depth of the upper offset point is 8.3m.Finally,large-scale trenching revealed that the actual buried depth of the upper offset point of the fault is 1.5m from the ground surface and there are paleoearthquake events of 5 stages.Combined with the preliminary result of corresponding sample age,we conclude the Yinchuan buried fault is a mid to late Holocene active fault. 相似文献
162.
Hiromasa Ishikawa Tsukasa Ohba Hirokazu Fujimaki 《Journal of Volcanology and Geothermal Research》2007
The ratio of 87Sr/86Sr was measured from different water samples of thermal/mineral (hot spring as well as crater lake) and meteoric origins, in order to specify the location and to verify the detailed model of a volcano-hydrothermal system beneath Zao volcano. The ratio showed a trimodal distribution for the case of thermal/mineral water: 0.7052–0.7053 (Type A, Zao hot spring), 0.7039–0.7043 (Type B, Okama crater lake and Shin-funkiko hot spring), and 0.7070–0.7073 (Type C, Gaga, Aone, and Togatta hot springs), respectively. However, in comparison, the ratio was found to be higher for meteoric waters (0.7077–0.7079). The water from the central volcanic edifice (Type B) was found to be similar to that of nearby volcanic rocks in their Sr isotopic ratio. This indicates that the Sr in water was derived from shallow volcanic rocks. The 87Sr/86Sr ratio for water from the Zao hot spring (Type A) was intermediate between those of the pre-Tertiary granitic and the Quaternary volcanic rocks, thus suggesting that the water had reacted with both volcanic and granitic rocks. The location of the vapor–liquid separation was determined as the boundary of the pre-Tertiary granitic and the Quaternary volcanic rocks by comparing the results of this strontium isotopic study with those of Kiyosu and Kurahashi [Kiyosu, Y., Kurahashi, M., 1984. Isotopic geochemistry of acid thermal waters and volcanic gases from Zao volcano in Japan. J. Volcanol. Geotherm. Res. 21, 313–331.]. 相似文献
163.
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165.
城市地震活断层探测的地球物理方法 总被引:8,自引:0,他引:8
通过国内外有关城市地震活断层探测的实例,对城市地震活断层探测的主要地球物理方法进行了介绍。由于城市地区特殊的干扰环境,城市地震活断层探测需要对传统的技术方法进行必要的改进和调整。以提高探测方法的抗干扰能力,城市地球地震活断层探测应充分利用高分辨浅层地震勘探和人工地震测深精度高的优势,根据不同城市的地球物理特征,配合电法勘探、磁法勘探、重力勘探和天然地震观测等其他地球物理方法,通过对资料的综合分析和解释,提高探测结果的分辨率和可靠性。 相似文献
166.
本文从变质岩带的含铀性分析入手,研究了赣中变质岩带中铀矿化与变质岩带的含铀性、构造岩浆活动带、变质岩带出露的动力学机制及变质核杂岩构造的关系。研究表明:铀成矿与构造岩浆活动带以及地壳减薄、地幔上隆和在变质核杂岩边缘沿着低角度正断层的地壳伸展构造有着实质的关系。 相似文献
167.
Quaternary vertical offset and average slip rate of the Nojima Fault on Awaji Island, Japan 总被引:5,自引:0,他引:5
Abstract Drilling was carried out to penetrate the Nojima Fault where the surface rupture occurred associated with the 1995 Hyogo-ken Nanbu earthquake. Two 500 m boreholes were successfully drilled through the fault zone at a depth of 389.4 m. The drilling data show that the relative uplift of the south-east side of the Nojima Fault (south-west segment) was approximately 230 m. The Nojima branch fault, which branches from the Nojima Fault, is inferred to extend to the Asano Fault. From the structural contour map of basal unconformity of the Kobe Group, the vertical component of displacement of the Nojima branch–Asano Fault is estimated to be 260–310 m. Because the vertical component of displacement on the Nojima Fault of the north-east segment is a total of those of the Nojima Fault of the south-west segment and of the Nojima branch–Asano Fault, it is estimated to total to 490–540 m. From this, the average vertical component of the slip rate on the Nojima Fault is estimated to be 0.4–0.45 m/103 years for the past 1.2 million years. 相似文献
168.
IntroductionWith the most feasible and powerful technical support provided by the high-precision GPS measurement for the study on horizontal crustal deformation, the obtainment of various-scale horizontal movement data and its study over the whole world is now in the ascendant, and its applicable fields is now expanding successively. In China, besides the GPS monitoring networks for different applications arranged by many agencies and departments, the key scientific project Crustal Movement… 相似文献
169.
There are 18 gullies displaying sinistral contortions to different degrees along the western terminal segment about 10 km long of the active Daqingshan piedmont fault near the Donghe District, Baotou City. The contortion amount of gullies ranges from 20 m to 300 m. The contortion and length of the gullies are in direct proportion. The relation between piedmont terraces and gullies indicates that the gullies with upper reaches of about 1 ~ 5 km long and those smaller than one kilometer were formed at the end of Late Pleistocene and Holocene.Meanwhile, sandy gravel layer of alluvial-proluvial sediment on the upthrown wall is directly in contact with yellow clayey sand of the downthrown wall. During the Holocene, the sinistral strike-slip rate along the western terminal segment of the active Daqingshan piedmont fault reached 5 mm/a from age data of dislocated sediments. The evolutional mechanism of the active Daqingshan piedmont fault is also discussed in the paper. 相似文献
170.
Su Young Lee Masatsugu Ohnishi Yasuhiro Shibata Makoto Wwatanabe Kenichi Hoshino Mayumi Jige Xiangping Gu Hitoshi Chiba Tamotsu Oomori Kantaro Fujioka Peter A. Rona 《Resource Geology》2001,51(1):63-68
Abstract: Pyrite rich in Zn, up to 3.1 wt%, was found in the TAG active mound of the TAG hydrothermal field, the slow-spreading Mid-Atlantic Ridge at 26°08'N and 44°49'W. The Zn-rich pyrite is characterized by an optical homogeneity, a homogeneous distribution of Zn in the back-scattered electron images, both at a magnification of about 500, a negative correlation between Fe and Zn contents of the pyrite and a rather small unit cell edge (a0 = 5.4117 ± 0.0008Å), strongly indicating that the detected Zn is present in the pyrite in solid solution. Such Zn concentrations are observed exclusively in dendritic pyrite, suggesting that the Znrich pyrite grew from hydrothermal fluids of a high degree of supersaturation due to quenching on the seafloor. 相似文献