East Asia-Wide Flat Slab Subduction and Jurassic Synorogenic Basin Evolution in West Korea

Egawa, Kosuke

doi:10.5772/56770

Cited by 7 publications

(8 citation statements)

References 77 publications

(138 reference statements)

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“…Although previous studies have suggested early Jurassic or later timing of this event, most recent geochemical, geochronological and structural investigations in NE and SE China show that onset of an active margin tectonics and the initiation of subduction of the palaeo-Pacific oceanic lithosphere beneath East China were under way by the early Triassic (Zhou et al 2014;Sun et al 2015;K Liu et al 2017) and perhaps even earlier in the late Permian (Wang et al 2005;Li et al 2006;Zhou et al 2006;Z-X Li et al 2012;Duan et al 2018;Shen et al 2018). Based on the findings of the work of FQ Zhang et al (2020), our work on Hainan (this study), and the findings of other recent studies Egawa, 2013;Domeier & Torsvik, 2014;Shen et al 2018), we postulate a latest Permianearly Triassic start of an active margin tectonics that marked the beginning of the Pacific Rim of Fire in its western domain near the eastern margin of East Asia in the western Pacific Ocean (Fig. 13a).…”

Section: Geodynamic Modelsupporting

confidence: 73%

Magmatic record of the Mesozoic geology of Hainan Island and its implications for the Mesozoic tectonomagmatic evolution of SE China: effects of slab geometry and dynamics in continental tectonics

Dilek

Tang

2020

Geol. Mag.

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Our field-based geochemical studies of the Triassic, Jurassic and Cretaceous granitoids on Hainan Island indicate that their magmas had different geochemical affinities, changing from alkaline in the Triassic through ocean island basalt (OIB) in the Jurassic, to calc-alkaline in the Cretaceous. We show that these changes in the geochemical affinities of the Mesozoic granitoids on Hainan and in SE China reflect different melt sources and melt evolution patterns through time. Our new geodynamic model suggests that: (1) Triassic geology was controlled by flat-slab subduction of the palaeo-Pacific plate beneath SE China. This slab dynamics resulted in strong coupling between the lower and upper plates, causing push-over tectonics and contractional deformation in SE China. Flat subduction-induced edge flow and aesthenospheric uprising led to the production of high-K granites, syenites and mafic rocks. (2) Slab foundering, accelerated subduction rates and subduction hinge retreat in the Early Jurassic caused rapid rollback of the downgoing slab. Strong decoupling of the upper and lower plates resulted in pull-away tectonics, producing extensional deformation in SE China. Decompression melting of the upwelling aesthenosphere produced OIB-type melts, which interacted with the subcontinental lithospheric mantle (SCLM) to form A- and I-type granitoids. (3) Segmentation of the palaeo-Pacific plate in the Early Cretaceous resulted in steeply dipping slabs and their faster rollback, facilitating lithospheric-scale extension and oceanward migration of calc-alkaline magmatism. This extensional deformation played a significant role in the formation of metamorphic core complexes, widespread crustal melting and development of a Basin and Range-type tectonics and landscape evolution in SE China.

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Section: Geodynamic Modelsupporting

confidence: 73%

Magmatic record of the Mesozoic geology of Hainan Island and its implications for the Mesozoic tectonomagmatic evolution of SE China: effects of slab geometry and dynamics in continental tectonics

Dilek

Tang

2020

Geol. Mag.

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“…The control of slab angle on arc position is supported by recent numerical modeling and global analyses in subduction systems (Grove et al, , , Figure 11a). The study of ancient and current flat‐slab processes has revealed a broad range of time span and arc width in these settings, which is likely related to the diversity of processes driving variations in slab dip (e.g., Payenia flat slab: 150–200 km, 13 Ma, Litvak et al, , Figure 2; Pampean flat slab, 230–200 km; 18 Ma to present, V. A. Ramos et al, , Figure 10; Laramide flat slab, 900 km, 45 Ma, Coney & Reynolds, ; South China flat slab, 1,000 km, 60 Ma, Li & Li, , Figure 3; South Korea flat slab, 250 km, 100 Ma, Figure 7 of Egawa, ). Slab shallowing could be compatible with the arc behavior observed in Figure as it may produce arc broadenings of 250 km and a subsequent magmatic shut‐off.…”

Section: Discussionmentioning

confidence: 99%

“…The control of slab angle on arc position is supported by recent numerical modeling and global analyses in subduction systems (Grove et al, 2009(Grove et al, , 2010 Figure 11a). The study of ancient and current flat-slab processes has revealed a broad range of time span and arc width in these settings, which is likely related to the diversity of processes driving variations in slab dip (e.g., Figure 7 of Egawa, 2013). Slab shallowing could be compatible with the arc behavior observed in Figure 9 as it may produce arc broadenings of 250 km and a subsequent magmatic shut-off.…”

Section: The Deseado Ftb In the Context Of The Cretaceous Andean Evolmentioning

confidence: 96%

Cretaceous Intraplate Contraction in Southern Patagonia: A Far‐Field Response to Changing Subduction Dynamics?

et al. 2018

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The origin, extent, and timing of intraplate contraction in Patagonia are among the least understood geological processes of southern South America. Particularly, the intraplate Deseado fold‐thrust belt (FTB), located in the Patagonian broken foreland (47°–48°30′S), is one of the most enigmatic areas. In this belt, time constraints on tectonic events are limited and synorogenic deposits have not been documented so far. Furthermore, the driving mechanism for intraplate contraction remains unknown. In this study, we carried out a structural and sedimentological analysis. We report the first syntectonic deposits in this area in the Baqueró (Aptian) and Chubut (Cenomanian/Campanian) groups and a newly found unit referred to as the Albian beds (109.9 ± 1.5 Ma). Thus, several contractional stages in late Aptian, Albian, and Cenomanian‐Campanian are then inferred. We suggest that the Deseado FTB constituted the southernmost expression of the early Patagonian broken foreland in Cretaceous times. Additionally, we analyzed the spatiotemporal magmatic arc behavior as a proxy of dynamic changes in the Andean subduction during determined stages of intraplate contraction. We observe a significant arc broadening from ~121 to 82 Myr and magmatic quiescence after ~67 Ma. This is interpreted as a slab shallowing to flattening process. Far‐field tectonic forces would have been produced by increased plate coupling linked to the slab flattening as indirectly indicated by the correlation between Cretaceous arc expansion and intraplate contraction. Finally, the tectonic evolution of the Deseado FTB favors studies supporting inception of Andean shortening since Cretaceous times.

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“…The Gimpo Group crops out along the western and northwestern margin of the Gyeonggi Massif (Kee, 2011;Kee et al, 2008) and forms the northernmost occurrence of the Daedong Supergroup in South Korea. The Daedong Supergroup in central South Korea comprises postcollisional, non-marine conglomerates, sandstones and coal-bearing shales with intercalated tuffs and tuffaceous rocks deposited in structurally controlled, fault-bounded (intra-arc) basins on a metamorphic basement (Egawa, 2013;H.-j. Lee et al, 2021;Lim & Cho, 2012).…”

Section: Gimpo Groupmentioning

confidence: 99%

“…Lee et al, 2021;Lim & Cho, 2012). Sediments of the Supergroup's lower part are metamorphosed and experienced ductile deformation (Egawa, 2013;Lim & Cho, 2012). The maximum illite crystallinity values indicate a high thermal maturity with average temperatures of the order of 320-340°C (Egawa, 2013).…”

Section: Gimpo Groupmentioning

confidence: 99%

40Ar/39Ar Age and Structural Constraints on Permian-Triassic and Jurassic Tectono-Metamorphic and Exhumation Phases in the Korean Collision Belt and Tectonic Implications

Jong

Ruffet

Han

2023

Preprint

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The Korean Collision Belt originally constituted a single coherent southwards-thinning tectonic wedge formed by accretion of the Qinling-type Barrovian metamorphic Jingok and Samgot units (Yeoncheon Complex) and Taean Formation onto the Sino–Korean Craton’s southern extension (Precambrian Gyeonggi Massif) while being underthrust by the South China Block. Detailed structural geological study and Ar/Ar laser-probe dating of 47 mineral single-grain and 2 whole-rock samples with both syn-collisional peak metamorphic and retrograde mineral assemblages reveal a prolonged tectonic evolution from the Devono–Carboniferous pre-collisional stage (375–370 Ma; ~315 Ma) to the Midde–Late Jurassic reactivation of the Permian–Triassic wedge during the second major exhumation phase of the Gyeonggi Massif (194–165 Ma). The latest Permian to Late Triassic main orogeny comprises three distinct correlated tectono-metamorphic phases. Essentially concordant (pseudo-)plateau ages (255.2–249.9 ± 0.4–0.9 Ma, 1σ) for main-phase-fabric-forming muscovite and biotite in the garnet, staurolite and kyanite zones and discordant late-stage andalusite-quartz veins (Jingok Unit) show fast cooling during exhumation from ~30 km to ≤12.5 km. Hornblendes (248.8–247.0 ± 0.6–1.6 Ma, 1σ) in the underlying higher-grade metamorphic, deeper underthrust Samgot Unit show later cooling. Fabric asymmetry implies cooling and age differences stem from (S)SE-ward exhumation along low-angle ductile normal faults. Incipient exhumation of mid-Triassic eclogites (Hongseong Belt) induced strong tectono-metamorphic reworking of the overriding plate (242–237 Ma; Yeoncheon Complex, Taean Formation, Gyeonggi Massif). Structurally downwards increasing resetting of mica (225–220 Ma), retrogression and overprinting by top-to the-north post-main-phase-shear constrains the Gyeonggi Massif’s further exhumation and cooling. Key Points: Korean Collision Belt: a southwards-tapering tectonic wedge with discrete tectono-metamorphic phases at 255–247, 245–237, 225–220 Ma 255–247 Ma: fast cooling, rapid exhumation, top-to-SE normal shear; 225–220 Ma: downwards increase retrogression, top-to-N normal shear 245–237 Ma: strong reworking; exhumation mid-Triassic eclogite; 194–165 Ma: final metamorphic reactivation and top-to-N normal shear

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East Asia-Wide Flat Slab Subduction and Jurassic Synorogenic Basin Evolution in West Korea

Cited by 7 publications

References 77 publications

Magmatic record of the Mesozoic geology of Hainan Island and its implications for the Mesozoic tectonomagmatic evolution of SE China: effects of slab geometry and dynamics in continental tectonics

Magmatic record of the Mesozoic geology of Hainan Island and its implications for the Mesozoic tectonomagmatic evolution of SE China: effects of slab geometry and dynamics in continental tectonics

Cretaceous Intraplate Contraction in Southern Patagonia: A Far‐Field Response to Changing Subduction Dynamics?

40Ar/39Ar Age and Structural Constraints on Permian-Triassic and Jurassic Tectono-Metamorphic and Exhumation Phases in the Korean Collision Belt and Tectonic Implications

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