Geometry and kinematics of the subsidiary faults of the Ilgwang fault, SE Korea

하상민,; Cheon, Youngbeom; 강희철,; Kim, Jong-Sun; leesonkap,; Son, Moon

doi:10.14770/jgsk.2016.52.1.31

Cited by 14 publications

(4 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We conclude that the more distributed pattern of deformation in the northern part of the incised valley relative to the southern part is probably related to the structural complexity within the intersection area between these two major fault zones. This interpretation is supported by recent studies on the structural evolution of SE Korea, which have identified multiple stages of movement on the Yangsan Fault since at least the Late Cretaceous, with the most intense phase (dextral movement) occurring during the Paleogene (e.g., Ha et al, 2016;Cheon et al, 2019), and the subsequent development of Miocene sedimentary basins, which are distributed only to the east of the Yangsan Fault (e.g., Sohn and Son, 2004;Son et al, 2013;Son et al, 2015).…”

Section: Spatiotemporal Tectonic Evolution Of the Ulsan Fault Zone An...supporting

confidence: 58%

Structural architecture and late Cenozoic tectonic evolution of the Ulsan Fault Zone, SE Korea: New insights from integration of geological and geophysical data

et al. 2023

Self Cite

View full text Add to dashboard Cite

Integration of geological and geophysical data is essential to elucidate the configuration and geometry of surface and subsurface structures, as well as their long-term evolution. The NNW–SSE-striking incised valley and parallel mountain range in the southeastern margin of the Korean Peninsula, extending 50 km from Gyeongju to Ulsan cities, are together regarded as one of the most prominent geographical features in South Korea. This paper presents an investigation into the structural architecture and deformation history of the valley and mountain range during the late Cenozoic based on combined data from field observations and gravity and electrical resistivity surveys. Our results based on integrated and reconciled geological, structural, and geophysical data are as follows. First, the incised fault valley can be divided into 1) the northern part, which comprises several distributed buried or exposed fault strands; and 2) the southern part, which comprises a concentrated deformation zone along the eastern margin of the valley. Different deformation features between the two parts are controlled by the lithology of host rocks and by the location and geometry of the neighboring major structures, that is, the Yeonil Tectonic Line (YTL) and the Yangsan Fault. Second, we defined the Ulsan Fault Zone as a NNW–SSE-to N–S-striking fault within the incised valley and along the eastern margin of the valley. In particular, the constituent strands located along the eastern margin of the valley have acted mainly as an imbricate thrust zone, characterized by an east-side-up geometry with moderate to low dip angles and reverse-dominant kinematics in the shallow subsurface during the Quaternary. Third, reactivated strands within the Ulsan Fault Zone during the Quaternary are interpreted as shortcut faults developed in the footwall of Miocene subvertical structures, predominantly the YTL. In addition, movements on the Ulsan Fault Zone and the YTL during the Miocene to Quaternary were arrested by the NNE–SSW-striking Yangsan Fault, which was a prominent and mature pre-existing structure. Our results highlight the spatiotemporal structural variation in SE Korea and emphasize the strong control of the configuration and geometry of pre-existing structures on the distribution and characteristics (i.e., geometry and kinematics) of the subsequent deformation under changing tectonic environments through the late Cenozoic.

show abstract

Section: Spatiotemporal Tectonic Evolution Of the Ulsan Fault Zone An...supporting

confidence: 58%

Structural architecture and late Cenozoic tectonic evolution of the Ulsan Fault Zone, SE Korea: New insights from integration of geological and geophysical data

et al. 2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recently, based on a compilation of previous results, Cheon et al. (2019) proposed the tectonic evolution of the fault and age constraints, including the following: (a) Late Cretaceous sinistral movement with a component of extensional deformation (e.g., NW–SE‐striking extensional structures, and the Dadaepo pull‐apart basin between the Yangsan and Dongnae faults; Cheon et al., 2017; Cho et al., 2007, 2016; Ha et al., 2016); (2) late Paleogene (∼43–23 Ma) dextral movement, which was the most intense phase of deformation on the fault, with 20–30 km of dextral offset being inferred from the distribution of several piercing points, such as A‐type granite bodies (see Figure 1c; Chang et al., 1990; Hwang, Lee, et al., 2007; Hwang, McWilliams, et al., 2007); and (c) subsequent reactivations along some segments during the late Miocene associated with sinistral kinematics (Chang, 2002; Chang & Chang, 1998; Choi et al., 2009). Gu et al.…”

Section: The Yangsan Faultmentioning

confidence: 99%

“…Multiple stages of deformation of the Yangsan Fault have been suggested by various structural observations and radiometric age determinations of transected rocks (e.g., Chang, 2002;Chang & Chang, 1998;Cheon et al, 2019;Cho et al, 2007Cho et al, , 2016Kim, 1992), as well as by K-Ar illite ages (Sim et al, 2017;Song et al, 2016Song et al, , 2019 and electron spin resonance ages Lee & Schwarcz, 2001;Yang, 2006;Yang & Lee, 2012 of fault gouge. Recently, based on a compilation of previous results, Cheon et al (2019) proposed the tectonic evolution of the fault and age constraints, including the following: (a) Late Cretaceous sinistral movement with a component of extensional deformation (e.g., NW-SE-striking extensional structures, and the Dadaepo pull-apart basin between the Yangsan and Dongnae faults; Cheon et al, 2017;Cho et al, 2007Cho et al, , 2016Ha et al, 2016); (2) late Paleogene (∼43-23 Ma) dextral movement, which was the most intense phase of deformation on the fault, with 20-30 km of dextral offset being inferred from the distribution of several piercing points, such as A-type granite bodies (see Figure 1c; Chang et al, 1990;Hwang, Lee, et al, 2007;; and (c) subsequent reactivations along some segments during the late Miocene associated with sinistral kinematics (Chang, 2002;Chang & Chang, 1998;Choi et al, 2009). Gu et al (2021) suggested that the structural maturity of the fault appears to fit the intermediate class (Class 2) following the criteria of Manighetti et al (2007) based on the minimum values of fault length on land (∼200 km), fault initiation age (>70 Ma), maximum long-term slip rate (∼0.4 cm/yr), and finite dextral offset (>20-30 km).…”

Section: Early Faultingmentioning

confidence: 99%

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

et al. 2022

Self Cite

View full text Add to dashboard Cite

An intraplate tectonic fault evolves with repeated seismic cycles that may exhibit multi‐mode slip behaviors (continuous aseismic sliding, slow slip with silent earthquakes, and earthquakes resulting from stick‐slip frictional instability). Here, we show long‐term (geological time scale) fault zone weakening processes and short‐term (seismic cycle scale) fault behavior of the Yangsan Fault, SE Korea, based on structural and mineralogical observations of an across‐strike fault zone sequence retrieved by inclined borehole drilling. Since the Late Cretaceous, physical and chemical weakening processes have formed a wide and complex fault zone characterized by interconnected clay‐rich fault core strands and fractured lenses. The deformation is more concentrated in the eastern block (Cretaceous sedimentary rock with felsic dikes) of the fault zone than in the western block (Paleogene granite) of the fault zone. The asymmetrical deformation pattern is controlled by the distinct properties of the different host rocks and differential fluid‐assisted reaction softening involving hydrothermal processes. Of the five main strands and numerous subsidiary strands in the wide fault zone, strand S1 between the sedimentary rock and granite has accommodated the largest displacements. In particular, the smectite‐rich, <2‐cm‐wide principal slip zone within S1 has acted as the major pathway for past seismic slip. Our findings consider that slow deformation in the sedimentary rocks formed the asymmetrical wide fault zone over long geological time, whereas that the preferential propagation of repeated seismic slip events propagated preferentially along the narrow principal slip zone of S1.

show abstract

“…Therefore, the limitations of the previous study were supplemented and information about intermediate and minor axes was extracted to obtain additional strain information. Previous studies have been conducted to investigate AMS that acquired information on the magnetic susceptibility of rocks, which was a similar concept to that used in this study [20,23,[36][37][38]. The AMS ellipsoid of the rock was calculated by measuring the strength according to the orientation of magnetic susceptibility at least six times, and the strain was analyzed using the orientation and crystallographic characteristics of the major, intermediate, and minor axes [39].…”

Section: Distribution Of Axes On Stereogrammentioning

confidence: 99%

3D Fabric Analysis in Fault Rock Using Synchrotron μ-CT: A Statistical Approach to SPO (Shape Preferred Orientation) for Estimation of Fault Motion

et al. 2020

View full text Add to dashboard Cite

This study provides information about fault motion by statistically presenting shape and orientation information for tens of thousands of grains. The recently developed shape preferred orientation (SPO) measurement method using synchrotron micro-computed tomography was used. In addition, various factors that were not considered in previous SPO analysis were analyzed in-depth. The study area included the Yangsan and Ulsan fault zones, which are the largest fault zones in the southeastern part of the Korean Peninsula. Samples were collected from five outcrops in two regions. According to the field observation results, the samples in the area were largely divided into fault gouge and cataclasite, and as a result of SPO analysis, we succeeded in restoring the three-dimensional fault motion direction for each outcrop and identified the fault type. In addition, the analysis results of the fault gouge and cataclasite samples collected from the thin fault zone were interpreted using the focal mechanism solution. As a result, the statistical SPO analysis approach supplements the shortcomings of previous research methods on two-dimensional planes and can quantitatively infer the three-dimensional fault motion for various fault rock samples in the same sequence, thus, presenting useful evidence for structural analysis.

show abstract

Geometry and kinematics of the subsidiary faults of the Ilgwang fault, SE Korea

Cited by 14 publications

References 31 publications

Structural architecture and late Cenozoic tectonic evolution of the Ulsan Fault Zone, SE Korea: New insights from integration of geological and geophysical data

Structural architecture and late Cenozoic tectonic evolution of the Ulsan Fault Zone, SE Korea: New insights from integration of geological and geophysical data

Long‐Term Weakening Processes and Short‐Term Seismic Slip Behavior of an Intraplate Mature Fault Zone: A Case Study of the Yangsan Fault, SE Korea

3D Fabric Analysis in Fault Rock Using Synchrotron μ-CT: A Statistical Approach to SPO (Shape Preferred Orientation) for Estimation of Fault Motion

Contact Info

Product

Resources

About