Jin-Han Ree

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Verified

Jin-Han verified their affiliation via an institutional email.

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• Ph.D.
• Professor at Korea University

The formations in the early Paleozoic Joseon Supergroup (mainly carbonates with subordinate siliciclastics) within the Taebaeksan Basin in the Danyang area, South Korea, show an apparent right-side-up homoclinal stratigraphy without repetition or omission of any formation, and it was therefore thought that the NW-dipping formation boundaries are pr...

The 2016 magnitude (MW) 5.5 Gyeongju earthquake, which occurred in Korea near assumed epicenters of several substantial historical earthquakes and Quaternary fault segments, underscores the importance of seismic hazard assessment in the region. However, uncertainties about potential seismic sources make evaluating the potential for a moderate-to-la...

The southeastern Korean Peninsula (SeKP) has experienced intense deformation owing to subduction and back-arc extension at the eastern continental margin of the Eurasian plate, leading to the formation of complex tectonic structures. Abnormally high surface heat flux, Cenozoic volcanism, signatures of mantle degassing and hydrothermal alteration, a...

Fault zones in crystalline rocks generally possess a relatively narrow (<50-cm-thick) fault core (i.e., a fault gouge layer/zone). However, the Geumwang Fault, a major strike-slip fault developed in granitic rocks in Korea, has a wider (∼24-m-thick) fault core with several gouge layers. Here we conduct detailed field and microanalytical investigati...

Clast–cortex aggregates (CCAs) have been commonly reported in experimental and natural fault gouges. Here we discuss the formation process of CCAs and its mechanical implications, based on experimentally simulated fault gouges. We conducted low- to high-velocity rotary shear experiments on Ca-bentonite gouges at a normal stress of 1 MPa, slip rates...

In this study, we probe the misalignment of 200 temporary broadband seismometers based on the polarization of P waves from regional and teleseismic earthquakes. The seismometers were deployed in the epicentral region of 2016 ML 5.8 Gyeongju earthquake, South Korea, and this unprecedented dense array provided a unique opportunity for investigating f...

A damaging Mw5.5 earthquake occurred at Pohang, South Korea, in 2017, after stimulating an enhanced geothermal system by borehole fluid injections. The earthquake was likely triggered by these operations. Current approaches for predicting maximum induced earthquake magnitude (Mmax) consider the volume of the injected fluid as the main controlling f...

The Taean Formation on the central western margin of the Korean Peninsula contains layered metapelite, quartzo‐feldspathic schist, amphibolite, calcsilicate, and impure marble. The layering was formed by tectonic transposition of the original bedding. The formation has lithologic and isotopic age signatures similar to those of metasedimentary rocks...

Frictional healing of faults is a key mechanism controlling fault strength recovery, which enables the development of repeating earthquake cycles. Carbonate fault rocks are commonly characterized by shiny mirror-like surfaces, sometimes referred to as fault mirrors. In spite of the prevalence of fault mirrors in both natural and experimental fault...

A commission of the Korean government on the 2017 Mw 5.5 Pohang earthquake concluded that seismic activity was triggered by fluid injection from the nearby Pohang enhanced geothermal system. The temporal and spatial distribution of hypocenters (depth range of 3–6 km) was recorded by our local seismic array for 345 days. It included, in addition to...

The 2017 Mw 5.5 Pohang earthquake in South Korea, the first reported and largest magnitude‐induced earthquake, occurred near the enhanced geothermal power plant in Pohang on 15 November 2017. We compute the spatiotemporal changes in poroelastic stresses perturbed by injected fluid under various conditions to better understand the occurrences of the...

Plain Language Summary The 2017 Pohang earthquake (Mw 5.5) raised a serious social debate as to whether it was triggered by the fluid injections at the Pohang enhanced geothermal system (EGS). In March 2019, the Overseas Research Advisory Committee organized by the Korean government authoritatively concluded that the Pohang event was triggered by h...

Crustal-scale shear zones developed on the boundaries of the Precambrian Gyeonggi Massif (GM) can play key role on understanding collisional orogeny during the Late Paleozoic to Early Mesozoic in the Korean Peninsula. Garnet schist formed on the boundary between the GM and Okcheon Metamorphic Belt (OMB) experienced contractional (Dn) and extensiona...

The 2017 ML 5.4 Pohang Earthquake in southeastern Korea, which was induced by fluid injection from an enhanced geothermal system, and its foreshock–aftershock sequence has been recorded by a dense and portable temporary seismic array. The hypocentral distribution of the earthquake sequence reveals the reactivation of a complex subsurface fault syst...

Obtaining a reliable age of the latest seismic slip event along an active fault is important for seismic hazard assessment. Here, we observe changes in the optically stimulated luminescence (OSL) signal of quartz crystals due to frictional heating in artificial fault gouges (comprising a mixture of quartz grains and Ca-bentonite powder). The fault...

Although the 2011 Tohoku-Oki earthquake (Mw 9.0, 11 March 2011) occurred more than 1,000 km from South Korea, it significantly changed the magnitudes and orientations of Global Positioning System (GPS) velocity vectors in the country, which took two years to return to preearthquake values. Then, areas with relatively thick crust show contractional...

Triggering quakes in a geothermal space Enhanced geothermal systems (EGSs) provide a potentially clean and abundant energy source. However, two magnitude-5 earthquakes recently occurred in South Korea during EGS site development. Grigoli et al. and Kim et al. present seismic and geophysical evidence that may implicate the second of these earthquake...

The geological relationship between the Okcheon and Taebaeksan basins of the Okcheon belt on the Korean peninsula is a key issue in reconstructing the tectonic evolution of the peninsula. The boundary between the two basin sequences has been variously interpreted as a conformable, unconformable, or thrust contact, without clear evidence being provi...

We review paleontologic evidence from the Upper Ordovician to Devonian strata in the Korean Peninsula and discuss their tectonostratigraphic origin. The Upper Ordovician–Devonian fossil-bearing strata are largely distributed in North Korea, and tectonostratigraphically in the southern margin of the Pyeongnam Basin and in the northern part of the Im...

Fabric transition by a switch in the dominant slip system of minerals in the plastic regime can be induced by changes in temperature, strain rate, or water content. We propose here this fabric transition by frictional heating in seismogenic fault zones in the brittle regime. The Garam Thrust in the Taebaeksan Basin of South Korea has a hanging wall...

A supposed ‘archaeocyath’ specimen from the Hyangsanni Formation of the Okcheon Basin (Okcheon Metamorphic Belt), Korea, reported about 50 years ago, has previously been used to constrain the depositional age of the metasedimentary succession in the basin. However, a re-examination of the specimen reveals that it lacks the typical morphology of arc...

We present new data on the crystal preferred orientation (CPO) and seismic properties of omphacite and lawsonite in extremely fresh eclogite from the southern Motagua fault zone, Guatemala, to discuss the seismic anisotropy of subducting oceanic crust. The CPO of omphacite is characterized by (010)[001], and it shows P-wave seismic anisotropies (AV...

Reconstruction of the Neoproterozoic to Early Cambrian paleogeography of northeast Asia proposed by Lee et al. (2016, Palaeogeography, Palaeoclimatology, Palaeoecology, 441, 770-786) is based on miscalculated statistical values and/or some radiometric data ignored without rationale. The Gondwana linkage between the Korean Peninsula and the Sino-Kor...

Experimental fault zones developed in Carrara marble that were deformed at seismic slip rates (1.18–1.30 m s-1) using a high-velocity-rotary-shear apparatus exhibit very low friction (friction coefficient as low as 0.06) at steady state due to nanoparticle lubrication of the decomposition product (lime). The fault zones show a layered structure; a...

The Permo–Triassic collision of the North and South China blocks caused the development of the Dabie– Sulu Orogen in China and Songrim Orogen in the Korean Peninsula. Extension after this collision is known from the Dabie–Sulu Orogen, but post-orogenic extension is not well defined in the Korean Peninsula. Extensional deformation along the southern...

This study delineates the collision belt (late Permian-Triassic) between the Sino-Korean and South China blocks in the northeast Asian margin, based on correlation of endemic fossil components (corals) in shallow marine deposits of the Silurian and Devonian, identified in both south China and southwest and northeast Japan. The Qinling-Dabie Belt in...

The establishment of robust Paleozoic tectonic links between parts of the Korean Peninsula and cratonic blocks within China remains uncertain, despite their important implications for the overall tectonic evolution of East Asia. Here we provide new SHRIMP U–Pb detrital zircon geochronological constraints on correlations between sedimentary rocks of...

The Permo-Triassic Songrim (Indosinian) orogeny in South Korea was a major tectonic event involving complicated continental collisions at the eastern margin of Eurasia. Previous studies have examined the structural and metamorphic features of the Songrim orogeny in each of the Paleozoic terranes of the orogenic belt (i.e., the Taebaeksan Basin, the...

Solidified frictional melts, or pseudotachylytes, remain the only unambiguous indicator of seismic slip in the geological record. However, pseudotachylytes form at >5 km depth, and there are many rock types in which they do not form at all. We performed low- to high-velocity rock friction experiments designed to impose realistic coseismic slip puls...

The Paleozoic Taebaeksan Basin in Korea suffered two major tectonic events, the Late Permian - Triassic collisional Songrim orogeny and the Middle Jurassic Daebo tectonic event. The distinction between the ``Songrim'' and ``Daebo'' structures in the basin has been difficult since both structures are known to have a similar orientation and vergence....

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 microstr...

The most widely used method for quantitative analyses of the spatial distribution of grains in a rock body is the nearest-neighbor method (a position-based method), which recognizes the grain center as the position of the grain without consideration of grain size or shape. However, the spatial distribution of grains is influenced by their size and...

The hanging-wall Cambrian dolostone and footwall Ordovician limestone of the Garam Thrust in the Taebaeksan Basin of Korea show markedly different microfabrics adjacent to a narrow (<1 cm) principal slip zone (PSZ). The dolostone of the hanging-wall consists of euhedral dolomite grains (160-200 μm) with some fossil fragments. The dolostone is highl...

The Silurian Hoedongri Formation of the Taebaeksan Basin of South Korea has been used as a key unit to the correlation of tectonic provinces of East Asia since the South China craton (or Yangtz block) contains Silurian-Devonian sequences as well as Cambrian-Ordovician ones in the Paleozoic basins while the North China craton (or Sino-Korea block) i...

The Deokpori Thrust, juxtaposing the early Paleozoic Yeongwol-type Joseon Supergroup (Yeongwol Group) against the Duwibong-type Joseon Supergroup (Taebaek Group) in the Okcheon belt, is an important regional structure in the Phanerozoic tectonic evolution of Korea. Although the initiation of the thrust has recently been conjectured to occur during...

Abstract The question of whether millennial-scale geological slip rates are consistent with decade-scale geodetic slip rates is of great importance in evaluating the nature of continental deformation within the Tibetan Plateau. We determined the time-averaged slip rate of the Sulu He segment of the Altyn Tagh Fault, near Changma in Gansu Province,...

Static adjustment of grain boundaries during the waning stage of deformation with sustained heat (e.g. at the end of an orogeny) has not been studied much, although it is important for the interpretation of microstructural status during the main stage of deformation. We report here that static adjustment of calcite grain boundaries is dependent on...

The coexistence of pseudotachylyte, a brittle fault rock representing seismic slip, and mylonite, a plastic or semiplastic fault rock associated with aseismic slip, has been debated for its origin in earthquake-generating faults. Deformation experiments on halite gouge at seismic slip rates show that mylonite forms simultaneously with frictional me...

Metasedimentary rocks of the Pyeongan Supergroup in the northeastern flank of the Taebaeksan Basin, South Korea, commonly contain two Al2SiO5 polymorphs (And+Ky and And+Sil), or more rarely, three coexisting Al2SiO5 polymorphs. Lower-grade rocks preserve chloritoid+andalusite±kyanite in muscovite–chlorite phyllite, and higher-grade rocks contain an...

The principal slip layer (PSL) along which most of the shear displacement within a fault zone occurs is very narrow (less than 1-5 mm) and it is not so clear how this narrow layer accommodates a large (several m to several km) displacement. The NNW-striking and WSW-dipping Garam Thrust puts the Cambrian Wagok Formation on top of the Ordovician Mung...

The Gongsuwon Thrust in the Taebaeksan Basin is one of the important regional structures for the Phanerozoic tectonic evolution of the Korean Peninsula. The late Early Jurassic Bansong Group (Daedong Supergroup) is structurally overlain by the early Paleozoic Joseon Supergroup along the thrust in the Yeongwol area. We present four lines of evidence...

Quantification of the strain distribution of the Altygn Tagh Fault in the northern Tibet, is of great importance for understanding the dynamics of the India-Eurasia collision. We determined time-averaged slip rate of the easternmost segment of the Altygn Tagh Fault around Changma in Gansu province by combining structural investigations, remote sens...

Recognition of seismic slip zone is important for a better understanding of earthquake generation processes in fault zones and paleoseismology. However, there has been no reliable record of ancient seismic slip except pseudotachylyte. Recently, it has been suggested that decomposition (dehydration or decarbonation) products due to frictional heatin...

Slip weakening is an essential process for large earthquakes to occur. Frictional melting has been known to be one of the effective slip weakening mechanisms, although there are some suggestions that frictional melt may strengthen fault during seismic slip. Our high-velocity friction experiments on a siltstone imply that frictional melt may act as...

Quartz ribbons in a quartz–muscovite mylonite from the Sunchang shear zone of South Korea show a variation in the average size (25−107 μm) of dynamically recrystallized quartz depending on the fraction and dispersion of muscovite within the ribbons. Micas within the quartz ribbons occur both inside quartz grains and along their boundaries, having a...

Pseudotachylyte formed by frictional melting has been the only unequivocal evidence of past seismogenic fault slip. We report from high-velocity friction experiments on sideritebearing gouge that mineral decomposition due to frictional heating also can leave evidence of paleoseismic events along shallow crustal faults other than pseudotachylyte. Ex...

We report a mingling behavior of granitic and andesitic melts produced by frictional heating in simulated faults of a syenite using a high-velocity rotary shear testing apparatus at Kyoto University. The syenite (so-called larvikite) is composed of perthitic alkali feldspar (~80%), mafic minerals (~15%), apatite (2 - 3%) and nepheline (1 - 2%). The...

Crystallographic preferred orientation (CPO)s of olivine and clinopyroxene in spinel peridotite from Baengnyeong Island in South Korea were investigated. Baengnyeong Island is located in the western most part of Korea in Yellow Sea and near the boundary between the Phanerozoic Imjingang belt and Precambrian Nangrim massif in North Korea. The Imjing...

Halite exhibits deformation behavior ranging from brittle to plastic at room temperature and at low pressures, and has been used to simulate deformation processes of the brittle-ductile transition zone. However, previous experiments on halite were performed at very low slip rates (10-9-10-3 m/s), requiring friction data at seismic slip rates for a...

This chapter describes a range of microdynamic processes that have been implemented in the software Elle or related codes. The first section describes the software Elle, which is the main software used in this book. The Elle software is included on the CD.

High-velocity weakening of faults may drive fault motion during large earthquakes. Experiments on simulated faults in Carrara marble at slip rates up to 1.3 meters per second demonstrate that thermal decomposition of calcite due to frictional heating induces pronounced fault weakening with steady-state friction coefficients as low as 0.06. Decompos...

There have been few studies on earthquake-generation processes in phyllosilicate-rich rocks, although pelitic rocks are common in seismogenic zones of foreland basins and subduction zones. Here, we report from high- velocity friction experiments on a siltstone that gouge-generating wear at a low normal stress (7.4 MPa) and low slip rates (0.17-0.55...

The spatial distribution pattern of constituent phases of rocks has important information for understanding nucleation processes of phases in igneous and metamotphic rocks, timing relationship between partial melting and deformation in migmatites, and effect of one phase on static or dynamic grain growth of another phase in metamorphic rocks. For t...

To understand the physico-chemical processes and dynamic frictional strength of carbonate-rich fault zones during seismic faulting, we conducted rotary shear friction tests at seismic slip-rates on carbonate rocks (calcite marble and dolomite marble) and artificial gouges of siderite and siderite-calcite-quartz mixture. Here, we report that thermal...

In the middle crust, deformation of granitic rocks is characterized by crystal plastic deformation of quartz and cataclasis of feldspar. For common granitic rocks with textures of framework feldspar and interstice-filling quartz, brittle strength of feldspar is a close approximation of the bulk rock strength because feldspar forms the load-bearing...

The Gongsuwon thrust together with the Deokpori (Gakdong) thrust in northeastern Okcheon belt is considered to be an important structure in understanding the tectonic evolution of the Korean peninsula following the Permian-Triassic collision between North and South China continents. We obtained Rb-Sr ages for Paleozoic sedimentary rocks around the...

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 st...

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 pr...

SUMMARYA recent paper published in Geophysical Journal International reports that the Late Palaeozoic to Early Mesozoic sedimentary rocks in the northeastern Okcheon belt of Korea were remagnetized during the Late Cretaceous to Early Tertiary, and argues that the remagnetization was triggered by fluids travelling more than 800 km from the subductin...

There has been a lack of seismic data in the Korean Peninsula mainly because it is in a seismically stable area within the Eurasian plate (or Amurian microplate) and because a network of seismic stations has been poor until recently. Consequently, first motion studies on the peninsula showed a large uncertainty or covered only local areas. Also, a...

Quartz ribbons in quartz-muscovite mylonite from the Honam shear zone of South Korea show a size variation of dynamically recrystallized quartz depending on fraction, size and distribution of mica. The quartz ribbons in muscovite matrix are 0.13 to 0.88 mm thick with axial ratio of 7 to 12. Quartz grains (5 to 200 μm) within the ribbons mostly have...

Feldspar grain-size reduction occurred due to the fracturing of plagioclase and K-feldspar, myrmekite formation and neocrystallization of albitic plagioclase along shear fractures of K-feldspar porphyroclasts in the leucocratic granitic rocks from the Yecheon shear zone of South Korea that was deformed under a middle greenschist-facies condition. T...

NE trending granitoid batholiths in South Korea are part of the huge Phanerozoic granitoid belt in east Asia. The crystallization ages of granitoid plutons show three episodes of Mesozoic magmatism in South Korea: Triassic (248–210 Ma), Jurassic (197–158 Ma), and Late Cretaceous–early Tertiary (110–50 Ma), with a Late Jurassic–Early Cretaceous (∼50...

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...

The Wangsan Fault in the Gyeongju area shows the largest known displacement of about 28 m among the Quaternary reverse faults in South Korea. Recent optically stimulated luminescence (OSL) age data of the Quaternary deposits cut by the fault have been interpreted as suggesting that the time-averaged slip rate and maximum recurrence interval of the...

Evolution of fault-zone strength and its weakening mechanisms during an earthquake are critical for understanding of earthquake rupture process. We report dramatic weakening of dry simulated faults in Carrara marble at seismic slip-rates, with frictional coefficient as low as 0.04 (probably the lowest record as rock friction). Calcite decomposition...

Deformation behavior of feldspar grains in granitic rocks is important in assessing crustal strength especially when they constitute a load-bearing framework. Grain-size reduction of feldspar can be achieved by fracturing and albite neocrystallization at greenschist facies condition, and by myrmekite formation, reaction and dissolution together wit...

We have developed a model for diffusion zoning development in garnet employing a numerical modeling system, Elle [Jessell et al. 2001]. The Elle system simulates textural development at thin section scale with an assumption that long term textural changes can be achieved by adding incremental processes. Many numerical models have been developed for...

We have modelled rigid-body rotation of growing prismatic porphyroblasts and development of internal foliation formed by capturing external foliation. Jefferey equations (1922) were used for the porphyroblast rotation with the assumptions that porphyroblasts are mechanically rigid objects embedded in a deforming ductile matrix. The growth rule appl...

Abstract Two groups of Quaternary faults occur in the southeastern Korean Peninsula. The first group is north-northeast-striking, high-angle dextral strike–slip faults. The second group is north-northeast-striking, low-angle reverse faults that represent the reactivation of the pre-existing normal faults. Optically stimulated luminescence dating of...

Quartz inclusions within intertectonic garnet porphyroblasts of metapelites from the southern Imjingang belt have a lattice preferred orientation. c-Axis fabrics of the quartz inclusions tend to show a single girdle pattern at a high angle to an earlier foliation together with a submaximum subparallel to an earlier lineation. This lattice preferred...

Structural analyses of three granitic plutons in the south central Okchon belt of the Korean peninsula reveal that the Baegnok and Cheongsan plutons are pretectonic with respect to right lateral strike-slip ductile shearing along the Cheongsan shear zone and later top to the ESE thrusting, whereas the Boeun pluton is posttectonic with respect to th...

In order to investigate the evolution of lattice preferred orientation (LPO) obtained during deformation, we carried out post-deformational annealing experiments for rock analog materials, octachloropropane (C3Cl8) and norcamphor (C7H10O). Polycrystalline aggregates deformed at low-temperature/high-strain-rate conditions show complete obliteration...

This review focuses on the tectonics and sedimentation of major sedimentary basins and orogenic belts (Late Proterozoic–Neogene) in the Korean peninsula. The Korean peninsula is part of the Amuria Plate and represents an important link between continental blocks of North and South China and the island arcs of Japan. The basement rocks, exposed in t...

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...

Grain boundary sliding is an important deformation process not only in diffusion creep but also in dislocation creep. The details of grain boundary sliding and associated accommodation mechanisms are discussed in experimentally deformed octachloropropane at a high homologous temperature. Grains unsuitably oriented for basal slip tend to deform by g...

We describe non-rotation of garnet porphyroblasts in non-coaxially deformed metapelites of the Imjingang orogenic belt in the middle Korean Peninsula. The three-dimensional geometry of inclusion trails within 1–2 mm garnet porphyroblasts was analyzed by serial polishing and reflected-light microscopy. Most of the garnet porphyroblasts have straight...

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 deforma...

Structural, petrological, and geochronological data from the middle Korean peninsula indicate that the Qinling-Dabie-Sulu collisional belt of east-central China crosses the Yellow Sea and extends into the Imjingang belt. The Yeoncheon complex, first identified as the western Imjingang belt, comprises primarily north-dipping metamorphic sequences: (...

In situ observations of grain boundary sliding and associated accommodation mechanisms in experimentally pure- and simple-sheared octachloropropane at 75–85% of its absolute melting temperature and at strain rates of 10−5-10−6 s−1 are discussed. Discontinuities in the strain, rotation and/or translation components of deformation across the grain bo...

The history of the intensity and orientation of a grain-shape foliation was investigated in octachloropropane deformed in simple shear at 80% of its absolute melting temperature and a shear strain-rate of 4 × 10−5S−1. Foliation orientation, developed from the beginning of the deformation, remains steady throughout the deformation. Foliation intensi...

Dynamic grain growth and lattice preferred orientation development in octachloropropane polycrystals simple-sheared at 0.8 Tm using synkinematic microscopy are discussed. Both soft and hard grains are observed to grow. It is suggested that globular grains are not necessarily an indicator of coaxial deformation. Strain heterogeneity is induced by pa...

Subgrain boundaries in thin sheets of octachloropropane deformed at 0.7–0.8 TM on the stage of a microscope are seen to appear in the material in seven different ways. Type I boundaries show the classical evolution by polygonization of bent crystals. Type II are essentially kink boundaries, which migrate sideways during deformation to reach their p...