The formation model of neotectonic fault zone in the Ulsan Fault Zone, Gyeongsang basin, Korea

2020 ◽  
Author(s):  
Ji-Hoon Kang
Keyword(s):  
Human Resource Development ◽  
Fault Zone ◽  
Korean Peninsula ◽  
Active Faults ◽  
Development Project ◽  
Strike Slip ◽  
Formation Model ◽  
The West ◽  
Quaternary Deposits ◽  
Gyeongsang Basin

<p>The Yangsan Fault Zone (YFZ) of NNE trend and Ulsan Fault Zone (UFZ) of NNW trend are developed in the Gyeongsang Basin, the southern part of the Korean Peninsula, and many active faults and Quaternary faults (ATV and QTY Fs) have been found in these fault zones. The tectonic movement of the YFZ can be explained at least by two different strike-slip movements, named as D1 sinistral strike-slip and D2 dextral strike-slip, and then two different dip-slip movements, named as D3 conjugate reverse-slip and D4 Quaternary reverse-slip. The surfaces of D3 fault in basement rocks are extended those of D4 fault in the covering Quaternary deposits, like the other Quaternary faults within the YFZ. The D3 and D4 faults were formed under the same compression of (N)NW-(S)SE direction. After that, the active faults occurred in the Korean Peninsula under the compression of E-W direction. The ATV and QTY Fs thrust the Bulguksa igneous rocks of Late Cretaceous-Early Tertiary upon the Quaternary deposits or are developed within the Quaternary deposits in the UFZ, showing the reverse-slip sense of top-to-the west movement. This presentation is suggested the formation model of neotectonic fault zone in the UFZ on the basis of the various trends [(W)NW, N-S, (E)NE trends] of fault surfaces of the ATV and QTY Fs found in the UFZ, and the zigzag-form connecting line of their outcrop sites, and the deformation history (the N-S trending 1st reverse-slip faulting by the 1st E-W compression and associated the E-W trending strike-slip tear faulting, the N-S trending 2nd reverse-slip faulting by the 2nd E-W compression) of neotectonic fault zone in the Singye-ri valley around the UFZ, and the compressive arc-shaped lineaments which convex to the west reported in the YFZ.</p><p>Acknowledgements: This research was financially supported by a grant (2017-MPSS31-006) from the Research and Development of Active fault of Korean Peninsula funded by the Korean Ministry of the Interior and Safety, and by Ministry of public Administration and Security as Disaster Prevention Safety Human resource development Project.</p>

scholarly journals Mantle degassing along strike-slip faults in the Southeastern Korean Peninsula

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hyunwoo Lee ◽  
Heejun Kim ◽  
Takanori Kagoshima ◽  
Jin-Oh Park ◽  
Naoto Takahata ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Korean Peninsula ◽  
Lower Crust ◽  
Hot Springs ◽  
Active Faults ◽  
Strike Slip ◽  
Southeastern Part ◽  
Ductile Shearing ◽  
Groundwater Wells ◽  
Ductile Lower Crust

Abstract On September 12, 2016, a ML 5.8 earthquake hit Gyeongju in the southeastern part of the Korean Peninsula (SeKP), although the area is known to be far from the boundary of the active plate. A number of strike-slip faults are observed in heavily populated city areas (e.g., Busan, Ulsan, Pohang, and Gyeongju). However, dissolved gases related to the active faults have rarely been studied despite many groundwater wells and hot springs in the area. Here we report new results of gas compositions and isotope values of helium and carbon dioxide (CO2) in fault-related fluids in the region. Based on gas geochemistry, the majority of gas samples are abundant in CO2 (up to 99.91 vol.%). Measured 3He/4He ratios range from 0.07 to 5.66 Ra, showing that the mantle contribution is up to 71%. The range of carbon isotope compositions (δ13C) of CO2 is from −8.25 to −24.92‰, showing mantle-derived CO2 is observed coherently where high 3He/4He ratios appear. The weakening of faults seems to be related to enhanced pressures of fluids containing mantle-derived helium and CO2 despite the ductile lower crust underneath the region. Thus, we suggest that the SeKP strike-slip faults penetrate into the mantle through ductile shearing.

Kinematic data on major Variscan strike-slip faults and shear zones in the Polish Sudetes, northeast Bohemian Massif

1997 ◽  
Vol 134 (5) ◽  
pp. 727-739 ◽  
Author(s):  
P. ALEKSANDROWSKI ◽  
R. KRYZA ◽  
S. MAZUR ◽  
J. ŻABA
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Bohemian Massif ◽  
Early Carboniferous ◽  
Shear Zones ◽  
Strike Slip ◽  
Late Carboniferous ◽  
Late Devonian ◽  
The West ◽  
West Sudetes

The still highly disputable terrane boundaries in the Sudetic segment of the Variscan belt mostly seem to follow major strike-slip faults and shear zones. Their kinematics, expected to place important constraints on the regional structural models, is discussed in some detail. The most conspicuous is the WNW–ESE Intra-Sudetic Fault Zone, separating several different structural units of the West Sudetes. It showed ductile dextral activity and, probably, displacement magnitude of the order of tens to hundreds kilometres, during late Devonian(?) to early Carboniferous times. In the late Carboniferous (to early Permian?), the sense of motion on the Intra-Sudetic Fault was reversed in a semi-brittle to brittle regime, with the left-lateral offset on the fault amounting to single kilometres. The north–south trending Niemcza and north-east–southwest Skrzynka shear zones are left-lateral, ductile features in the eastern part of the West Sudetes. Similarly oriented (northeast–southwest to NNE–SSW) regional size shear zones of as yet undetermined kinematics were discovered in boreholes under Cenozoic cover in the eastern part of the Sudetic foreland (the Niedźwiedź and Nysa-Brzeg shear zones). One of these is expected to represent the northern continuation of the major Stare Mesto Shear Zone in the Czech Republic, separating the geologically different units of the West and East Sudetes. The Rudawy Janowickie Metamorphic Unit, assumed in some reconstructions to comprise a mostly strike-slip terrane boundary, is characterized by ductile fabric developed in a thrusting regime, modified by a superimposed normal-slip extensional deformation. Thrusting-related deformational fabric was locally reoriented prior to the extensional event and shows present-day strike-slip kinematics in one of the sub-units. The Sudetic Boundary Fault, although prominent in the recent structure and topography of the region, was not active as a Variscan strike-slip fault zone. The reported data emphasize the importance of syn-orogenic strike-slip tectonics in the Sudetes. The recognized shear sense is compatible with a strike-slip model of the northeast margin of the Bohemian Massif, in which the Kaczawa and Góry Sowie Units underwent late Devonian–early Carboniferous southeastward long-distance displacement along the Intra-Sudetic Fault Zone from their hypothetical original position within the Northern Phyllite Zone and the Mid-German Crystalline High of the German Variscides, respectively, and were juxtaposed with units of different provenance southwest of the fault. The Intra-Sudetic Fault Zone, together with the Elbe Fault Zone further south, were subsequently cut in the east and their eastern segments were displaced and removed by the younger, early to late Carboniferous, NNE–SSW trending, transpressional Moldanubian–Stare Mesto Shear Zone.

Deformation of continental blocks within convergent plates: Anatolia as a case study

2020 ◽  
Author(s):  
Cengiz Zabcı ◽  
Taylan Sançar ◽  
Müge Yazıcı ◽  
Anke M. Friedrich ◽  
Naki Akçar
Keyword(s):  
Fault Zone ◽  
Plate Boundary ◽  
Slip Rate ◽  
Shear Zones ◽  
Strike Slip ◽  
Central Anatolia ◽  
Western Boundary ◽  
The West ◽  
Secondary Importance ◽  
Continental Block

<p>Anatolia is part of the west-central Alpide plate-boundary zone, particularly where the deformation is characterized by the westward extrusion of this continental block between the Arabian-Eurasian collision in the east and the Hellenic Subduction in the west. Although, this motion mostly happens along the boundary structures, i.e., the North Anatolian and East Anatolian shear zones, there are multiple studies documenting the active deformation along NE-striking sinistral and NW-striking dextral strike-slip faults within the central and eastern parts of Anatolia. These secondary faults slice Anatolia into several pieces giving formation of the Malatya-Erzincan, Cappadocian and Central Anatolian slices from east to west, where their boundary geometries are strongly controlled by the weak zones, the Tethyan Suture Zones.</p><p>We compiled all geological slip-rate and palaeoseismological studies, which point out inhomogeneous magnitude of deformation along different sections of these secondary structures. The Central Anatolian Fault Zone, the westernmost NE-striking sinistral strike-slip structure and the western boundary between the Central Anatolia and Cappadocian slices, has an average horizontal slip-rate of about 1 to 1.5 mm/a for the last few tens of thousands of years. The earthquake recurrence of about 4500 years between two events revealed on the northern sections of the CAFZ also support this rate of deformation. However, the Malatya-Ovacık Fault Zone has a bimodal behaviour in terms of deformation rate, which is 2.5 times higher along its northern member, the Ovacık Fault (OF) than the southern one, the Malatya Fault (MF) (2.5 to 1 mm/a), respectively. This velocity difference between two distinct members of the same fault zone can be explained by the relative westward motion of slices where the OF makes the direct contact between the Central Anatolian and Malatya-Erzincan, and the MF delimits Cappadocian and Malatya-Erzincan slices. Although these structures, which are shallow and probably deform only the upper crust, are of having secondary importance, yet they are still capable of producing infrequent but strong earthquakes within this highly deforming convergent setting. This study is supported by TÜBİTAK projects no. 114Y227 and 114Y580.</p>

scholarly journals Fractured latest Devonian granites of the West Moose River pluton along the Cobequid Shear Zone, Nova Scotia: implications for regional mineralization

2017 ◽  
Vol 54 (11) ◽  
pp. 1119-1137 ◽  
Author(s):  
Georgia Pe-Piper ◽  
David J.W. Piper ◽  
Angeliki Papoutsa ◽  
Joshua Wisen
Keyword(s):  
Fault Zone ◽  
Earth Element ◽  
Country Rock ◽  
Strike Slip ◽  
The West ◽  
Ree Mineralization ◽  
Mineral Assemblages ◽  
Complex Sequences ◽  
Host Complex ◽  
Moose River

Latest Devonian (∼365–358 Ma) A-type granites in the Cobequid Highlands host complex sequences of rare-earth element (REE) and other hydrothermal minerals. The West Moose River pluton is the only pluton truncated and brittly deformed by the mid-Carboniferous (∼327 Ma) strike-slip Minas Fault Zone during the Alleghanian orogeny. Fractures in the granite provide a record of several deformational and hydrothermal events with distinct mineral assemblages. Early sodic alteration produced albitization of feldspar, and riebeckite and tourmaline veins. The δ18O of albite and albitized granite (5‰–6‰) is similar to other regional granites, suggesting a mantle source of albitizing fluids. Nearby halite deposits are younger and thus not a source of Na. Early chlorite veins were followed by potassic alteration and hydrothermal biotite, and by diabase and lamprophyre dyke emplacement. Euhedral magnetite occupies new cross-cutting fractures and vugs, correlated with regional iron oxide – carbonate – sulphide mineralization following initiation of the Minas Fault Zone. This change in stress field resulted in widespread fracturing of the granite, greatly increasing its permeability. Magnetite is postdated by titania minerals with hydrothermal REE minerals in dissolution voids. The spatial variation in REE mineral types indicates variable availability of F, Cl, and CO2 in mineralizing fluids derived from groundwater. REE mineralization is rare in veins in country rock, demonstrating local plutonic sources of REEs. The emplacement of REE minerals was complex in time and space and was a consequence of pervasive microfracturing of the granite.

The Ny Friesland Orogen, Spitsbergen

1992 ◽  
Vol 129 (6) ◽  
pp. 679-707 ◽  
Author(s):  
W. B. Harland ◽  
R. A. Scott ◽  
K. A. Auckland ◽  
I. Snape
Keyword(s):  
Fault Zone ◽  
Strike Slip ◽  
Central Province ◽  
The West ◽  
Eastern Province ◽  
Shallow Marine ◽  
Western Province ◽  
Slip Regime ◽  
Facies Metamorphism ◽  
Slip Displacement

AbstractThe Caledonides of Ny Friesland comprise the type Hecla Hoek sequence of Svalbard, a succession of late Proterozoic to Ordovician strata greater than 18 km thick. Three supergroups constitute the sequence: the Stubendorffbreen Supergroup (Riphean), the Lomfjorden Supergroup (late Riphean-Sturtian) and the Hinlopenstretet Supergroup (Varanger-mid-Ordovician). Basement elements have recently been identified within the Stubendorffbreen Supergroup, but their extent and significance is yet to be established. The Stubendorffbreen Supergroup records the deposition of sediments and volcanics (both acid and basic) in an unstable marine environment. In contrast, the Lomfjorden and Hinlopenstretet supergroups record sedimentation in a shallow-marine, periodically emergent, stable environment without volcanism. The Ny Friesland Orogen is divided into two subterranes by the Veteranen Line, a zone of attenuation along which sinistral strike-slip displacement has occurred. This line separates the strongly deformed Stubendorffbreen Supergroup rocks in the west from the less-intensely deformed Lomfjorden and Hinlopenstretet supergroup rocks in the east. Despite these contrasts and the obvious displacement, there is no evidence that a significant stratigraphie break occurs across it.All the supergroups were deformed and metamorphosed during the late Ordovician-Silurian Ny Friesland Orogeny. Early compressional deformation produced isoclinal folding and nappes in the Stubendorffbreen Supergroup rocks, accompanied by amphibolite faciès metamorphism; deformation in the Lomfjorden and Hinlopenstretet supergroups was less intense with open, upright folds and greenschist or subgreenschist facies metamorphism. Early compression was followed by a Silurian transpressive deformation that generated a pervasive lineation in the Stubendorffbreen Supergroup rocks. Transpressive deformation and the associated sinistral strike-slip was focused where strata were in a near-vertical attitude conducive to displacement. At a late stage in the orogeny, and probably still under a strike-slip regime, batholiths were emplaced into rocks east of the Veteranen Line.As a result of continued sinistral displacement (transpression, transcurrence and transtension) along the Billefjorden Fault Zone, Ny Friesland (part of the Eastern Province of Svalbard) finally docked against the Central Province during the late Devonian Svalbardian movements. At the same time, the Central Province docked against the Western Province. In total, hundreds of kilometres of Caledonian displacement along the Billefjorden Fault Zone brought the Eastern and Central provinces into their present positions. Pre-Carboniferous Svalbard is thus a composite terrane of at least three provinces, each comprising more than one minor terrane.

scholarly journals Source processes of large earthquakes along the Xianshuihe fault in southwestern China

1983 ◽  
Vol 73 (2) ◽  
pp. 537-551
Author(s):  
Huilan Zhou ◽  
Hsui-Lin Liu ◽  
Hiroo Kanamori
Keyword(s):  
Fault Zone ◽  
Body Wave ◽  
Active Faults ◽  
Strike Slip ◽  
The Body ◽  
Southwestern China ◽  
Total Moment ◽  
Lateral Strike Slip ◽  
Largest Aftershock ◽  
Large Earthquakes

abstract The Xianshuihe fault is one of the most active faults in southwestern China. Recently, three large earthquakes occurred along it in 1967 (Ms = 6.1), 1973 (Ms = 7.5), and 1981 (Ms = 6.8). The 1981 event occurred near the central portion of the fault zone. Modeling of the body and surface waves indicates pure left-lateral strike-slip motion on a vertical fault striking N40°W consistent with the surface trend of the Xianshuihe fault. Two major ruptures are suggested for this source, with a total moment of 1.3 ×1026 dyne-cm. The 1973 event occurred about 65 km northwest of the 1981 event and ruptured about 90 km bilaterally along the fault. The body-wave synthetics indicate three main ruptures during faulting within 43 sec, with a total moment of 1.8 ×1027 dyne-cm. The mechanisms are similar to the 1981 event, and the average slip is determined to be 3.8 m. The largest aftershock (Ms = 5.9) occurred 1 day after the main event with a normal-fault mechanism striking almost perpendicular to the surface breakage. The 1967 event occurred at the northwestern end of the fault zone, with a strike of N65°E. It had a nearly normalfault mechanism with a seismic moment of 4.5 ×1025 dyne-cm. The largest aftershock (Ms = 5.1) occurred 7 hr later with a similar focal mechanism. The primary faulting along the Xianshuihe fault is left-lateral strike-slip, but the normal faulting with strike direction about perpendicular to the Xianshuihe fault trace is common, especially in the northwestern segment. The faulting pattern in this region is consistent with the regional stress field caused by the India-Tibet collision. The normal event which is not on the major fault seems to have more frequent foreshocks and aftershocks than those on the main fault.

scholarly journals Kinematic partitioning in the Southern Andes (39° S–46° S) inferred from lineament analysis and reassessment of exhumation rates

2021 ◽  
Author(s):  
Paul Leon Göllner ◽  
Jan Oliver Eisermann ◽  
Catalina Balbis ◽  
Ivan A. Petrinovic ◽  
Ulrich Riller
Keyword(s):  
Fault Zone ◽  
Vertical Displacement ◽  
Strike Slip ◽  
Structural Studies ◽  
Southern Andes ◽  
Plate Convergence ◽  
Exhumation Rates ◽  
Lineament Analysis ◽  
Dextral Strike Slip ◽  
Data Call

AbstractThe Southern Andes are often viewed as a classic example for kinematic partitioning of oblique plate convergence into components of continental margin-parallel strike-slip and transverse shortening. In this regard, the Liquiñe-Ofqui Fault Zone, one of Earth’s most prominent intra-arc deformation zones, is believed to be the most important crustal discontinuity in the Southern Andes taking up margin-parallel dextral strike-slip. Recent structural studies, however, are at odds with this simple concept of kinematic partitioning, due to the presence of margin-oblique and a number of other margin-parallel intra-arc deformation zones. However, knowledge on the extent of such zones in the Southern Andes is still limited. Here, we document traces of prominent structural discontinuities (lineaments) from the Southern Andes between 39° S and 46° S. In combination with compiled low-temperature thermochronology data and interpolation of respective exhumation rates, we revisit the issue of kinematic partitioning in the Southern Andes. Exhumation rates are maximal in the central parts of the orogen and discontinuity traces, trending predominantly N–S, WNW–ESE and NE–SW, are distributed across the entire width of the orogen. Notably, discontinuities coincide spatially with large gradients in Neogene exhumation rates and separate crustal domains characterized by uniform exhumation. Collectively, these relationships point to significant components of vertical displacement on these discontinuities, in addition to horizontal displacements known from published structural studies. Our results agree with previously documented Neogene shortening in the Southern Andes and indicate orogen-scale transpression with maximal vertical extrusion of rocks in the center of the transpression zone. The lineament and thermochronology data call into question the traditional view of kinematic partitioning in the Southern Andes, in which deformation is focused on the Liquiñe-Ofqui Fault Zone.

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