排序方式: 共有17条查询结果,搜索用时 12 毫秒
1.
Fault slip analysis of Quaternary faults in southeastern Korea 总被引:1,自引:0,他引:1
The Quaternary stress field has been reconstructed for southeast Korea using sets of fault data. The subhorizontal direction of the maximum principal stress (σ1) trended ENE and the direction of the minimum principal stress (σ3) was nearly vertical. The stress ratio (Φ = (σ2 − σ3) / (σ1 − σ3)) value was 0.65. Two possible interpretations for the stress field can be made in the framework of eastern Asian tectonics; (1) The σHmax trajectory for southeast Korea fits well with the fan-shaped radial pattern of maximum principal stress induced by the India–Eurasia collision. Thus, we suggest that the main source for this recent stress field in southeast Korea is related to the remote India–Eurasia continental collision. (2) The stress field in Korea shows a pattern similar to that in southwestern Japan. The origin for the E–W trending σHmax in Japan is known to be related to the mantle upwelling in the East China Sea. Thus, it is possible that Quaternary stress field in Korea has evolved synchronously with that in Japan. We suggest further studies (GPS and in situ stress measurement) to test these hypotheses. 相似文献
2.
3.
Jong-Chan Park Woohan Kim Tae Woong Chung Chang-Eob Baag Jin-Han Ree 《Geophysical Journal International》2007,169(3):1103-1114
We evaluate the stress field in and around the southern Korean Peninsula with focal mechanism solutions, using the data collected from 71 earthquakes ( ML = 1.9–5.2) between 1999 and 2004. For this, the hypocentres were relocated and well-constrained fault plane solutions were obtained from the data set of 1270 clear P -wave polarities and 46 SH / P amplitude ratios. The focal mechanism solutions indicate that the prevailing faulting types in South Korea are strike-slip-dominant-oblique-slip faultings with minor reverse-slip component. The maximum principal stresses (σ1 ) estimated from fault-slip inversion analysis of the focal mechanism solutions show a similar orientation with E–W trend (269°–275°) and low-angle plunge (10°–25°) for all tectonic provinces in South Korea, consistent with the E–W trending maximum horizontal stress (σHmax ) of the Amurian microplate reported from in situ stress measurements and earthquake focal mechanisms. The directions of the intermediate (σ2 ) and minimum (σ3 ) principal stresses of the Gyeongsang Basin are, however, about 90 deg off from those of the other tectonic provinces on a common σ2 –σ3 plane, suggesting a permutation of σ2 and σ3 . Our results incorporated with those from the kinematic studies of the Quaternary faults imply that NNW- to NE-striking faults (dextral strike-slip or oblique-slip with a reverse-slip component) are highly likely to generate earthquakes in South Korea. 相似文献
4.
The crustal-scale Kyonggi shear zone of central Korea has been identified as a major boundary between the Precambrian Kyonggi massif in the south and the Imjingang belt in the north. The latter is an eastward extension of the Qinling-Dabie-Sulu collisional belt of China. Field observations and microstructural analysis indicate that the extensional shear zone evolved from a deep crustal ductile regime to a shallow crustal brittle regime, associated with a rapid uplift of the Kyonggi massif following the Late Permian-Early Triassic collision between the Sino-Korean and Yangtze cratons. A Rb-Sr muscovite age (226+/-1.2 Ma) of the mylonite suggests that the extensional ductile shearing occurred during the Late Triassic. 相似文献
5.
Hyeong Soo Kim Jin-Han Ree Jeongmin Kim 《International Journal of Earth Sciences》2012,101(2):499-501
6.
Octachloropropane (C3C18) was sheared using a press mounted on an optical microscope and then allowed to adjust its microstructure statically, at the deformation temperature. Depending on strain rate and deformation temperature, the post-deformational changes in microstructure are strikingly different. After low temperature-high strain-rate deformation, fast growth of new strain-free grains on the boundaries of deformed grains results in the obliteration of grain-shape foliation and intracrystalline deformation features, and the development of a foam texture. After high temperature—low strain-rate deformation, on the other hand, grain-shape foliation and grains with subgrain boundaries tend to survive the adjustment. Lattice preferred orientation is maintained after the post-deformational adjustment at both deformation conditions and thus remains a good indicator of deformation. 相似文献
7.
Origin of Mesozoic gold mineralization in South Korea 总被引:6,自引:0,他引:6
Abstract The Mesozoic gold–silver deposits in South Korea are closely associated with the Mesozoic granitoids. The Jurassic gold–silver deposits can be distinguished from the Cretaceous ones in terms of occurrence, alteration style, gold fineness, associated mineral assemblage, fluid inclusion and stable isotopic compositions. The Jurassic deposits were formed in mesozonal environments related to deep-seated granitoids, whereas the Cretaceous ones were formed in epizonal environments related to shallow-level granitoids. The Jurassic auriferous deposits (about 165–145 Ma) show fluid characteristics typical of an orogenic-type gold deposit, and were probably generated in a compressional regime caused by an orthogonal convergence of the Izanagi oceanic plate into the Asiatic margin. However, strike-slip faults and caldera-related fractures, together with subvolcanic to volcanic activity, may have played an important role in the formation of Cretaceous gold–silver lode deposits (about 110–45 Ma) under a continental arc setting. 相似文献
8.
Raehee Han Jin-Han Ree Deung-Lyong Cho Sung-Tack Kwon Richard Armstrong 《Gondwana Research》2006,9(1-2):106
The Bansong Group (Daedong Supergroup) in the Korean peninsula has long been considered to be an important time marker for two well-known orogenies, in that it was deposited after the Songnim orogeny (Permian–Triassic collision of the North and South China blocks) but was deformed during the Early to Middle Jurassic Daebo tectonic event. Here we present a new interpretation on the origin of the Bansong Group and associated faults on the basis of structural and geochronological data. SHRIMP (Sensitive High-Resolution Ion MicroProbe) U–Pb zircon age determination of two felsic pyroclastic rocks from the Bansong Group formed in the foreland basin of the Gongsuweon thrust in the Taebaeksan Basin yielded ages of 186.3 ± 1.5 and 187.2 ± 1.5 Ma, respectively, indicating the deposition of the Bansong Group during the late Early Jurassic. Inherited zircon component indicates ca. 1.9 Ga source material for the volcanic rocks, agreeing with known basement ages.The Bansong Group represents syntectonic sedimentation during the late Early Jurassic in a compressional regime. During the Daebo tectonic event, the northeast-trending regional folds and thrusts including the Deokpori (Gakdong) and Gongsuweon thrusts with a southeast vergence developed in the Taebaeksan Basin. This is ascribed to deformation in a continental-arc setting due to the northwesterly orthogonal convergence of the Izanagi plate on the Asiatic margin, which occurred immediately after the juxtaposition of the Taebaeksan Basin against the Okcheon Basin in the late stage of the Songnim orogeny. Thus, the Deokpori thrust is not a continental transform fault between the North and South China blocks, but an “intracontinental” thrust that developed after their juxtaposition. 相似文献
9.
10.
Hyeong Soo Kim Jin-Han Ree Jeongmin Kim 《International Journal of Earth Sciences》2012,101(2):483-498
The deformed and metamorphosed middle Pennsylvanian to Early Triassic (?) rocks of the Pyeongan Supergroup, occurring in northeastern flank of the Paleozoic Taebaeksan Basin, east central South Korea, record the impact of the Late Permian–Triassic Songrim (Indosinian) collisional orogeny in the eastern Eurasia margin. Analysis of meso- and microstructures and their relationship with porphyroblast growth has revealed that these metasedimentary rocks were affected by four deformation events (D1–D4). During the polyphase deformations, successive foliations with alternately steep (S1 and S3) and flat-lying (S2 and S4) orientations were produced with growth of chloritoid, andalusite and kyanite porphyroblasts during D1 and D2, and growth of garnet, staurolite and andalusite porphyroblasts during D3 and D4. SHRIMP U–Pb detrital zircon ages (330–310 Ma) from metapelites in the oldest unit of the Pyeongan Supergroup in the study area, combined with the previous data on sandstone compositions, indicate magmatic activity that was contemporaneous with the initial deposition of the Pyeongan Supergroup. This also suggests that the Pyeongan Supergroup was deposited in an arc-related foreland basin at an active continental margin during the Late Carboniferous and Permian time. Two contractional deformation events (D1 and D3) and two events related to gravitational flattening (D2 and D4), along with Barrovian-type medium-pressure regional metamorphism, may have resulted from the Late Permian–Triassic Songrim orogeny, related to collision between the North and South China blocks and/or collision between the Eastern Eurasia margin and the proto-Japan terrane. 相似文献