Inversion of a hyper-extended rifted margin in the southern Central Range of Taiwan

McIntosh, K. D.; Avendonk, H. J. Van; Lavier, L. L.; Lester, W. R.; Eakin, D. H.; Wu, Francis T.; Liu, Char‐Shine; Lee, Chao Shing

doi:10.1130/g34402.1

Cited by 119 publications

(137 citation statements)

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“…Thus, southern Taiwan (Hengchun Peninsula) and its offshore extension on the Hengchun Ridge to the north of 21 o N are in the early stage of mountain building due to active collision, which began latter than that of the north part at about 5 Ma. South of 21 o N, the offshore Hengchun Ridge likely represents the 'pre-collision' conditions of the southern Chinese margin and Manila trench subduction system (Byrne and Liu, 2002; A C C E P T E D M A N U S C R I P T McIntosh et al, 2013). Thus, the Hengchun Peninsula records a history of the intra-oceanic subduction prior to 5 Ma and since then it has been a site of arc-continent collision (Fig.…”

Section: Accepted Manuscriptmentioning

confidence: 95%

“…tectonic mélange) can be transported upward along these mega-thrusts. Moreover, new marine seismic reflection and coincident wide-angle ocean-bottom seismometer data acquired offshore Taiwan show a chaotic area underlying the Hengchun Ridge accretionary complex(Lester et al, 2013). This may represent the early syn-subduction stage of formation of the Kenting Mélange, which was then transported to the shallow level in the accretionary complex.…”

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From convergent plate margin to arc–continent collision: Formation of the Kenting Mélange, Southern Taiwan

et al. 2016

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A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTThe Kenting Mélange on the Hengchun Peninsula, Taiwan, formed through tectonic shearing of subduction complex lithologies, probably within the plate boundary subduction channel between the Eurasian and Philippine Sea plates, with further deformation and exhumation in the Pliocene-Pleistocene during arc-continent collision. Field relations reveal a structural gradation from normal stratified turbidite sequence (Mutan Formation) through broken formation to highly sheared Kenting Mélange containing allochthonous polygenic blocks. This gradation is consistent with an increase of average vitrinite reflection values from ~0.72% in the Mutan Formation through ~0.93% in the broken formation to ~0.99% in the mélange, suggesting temperatures of at least 140 ºC during formation of the Kenting Mélange. Zircons from gabbro in the Kenting Mélange are dated as 25.46 ± 0.18 Ma, which together with geochemical data constrains the source to South China Sea oceanic lithosphere.In combination with the field relationships, vitrinite reflectance values, microfossil stratigraphy and offshore geophysical data from S and SE Taiwan, we propose that the Kenting Mélange initially formed at the subduction plate boundary from offscraped trench deposits. Minor Plio-Pleistocene microfossils (<5%) occur within the mélange in proximity to slope basin of equivalent age and were likely sheared into the mélange during out-of-sequence thrusting associated with active arc-continent collision, which in the Hengchun Peninsula commenced after 6.5 Ma.

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From convergent plate margin to arc–continent collision: Formation of the Kenting Mélange, Southern Taiwan

et al. 2016

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“…The oceanic crust in the northern SCS has generally been interpreted to be present only south of approximately 20°N based on magnetic anomalies (Taylor and Hayes, 1980;Briais et al, 1993). North of this, a velocity profile of OBS1995 across the Hengchun Peninsula off SW Taiwan shows that 11-16-km-thick transitional crust subducts eastward beneath the Manila Trench (McIntosh et al, 2005(McIntosh et al, , 2013. Recent seismic reflection and wide-angle data indicate that the transitional crust at the northeastern margin of the SCS is highly extended with typical thicknesses of 7-15 km and is even hyper-extended (here, <4 km thick) in places (Van Avendonk et al, 2009;Pichot et al, 2013;Lester et al, 2014).…”

Section: Cot At the Mid-northern Margin Of The Scsmentioning

confidence: 97%

The continent–ocean transition at the mid-northern margin of the South China Sea

Gao

McIntosh

et al. 2015

Tectonophysics

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“…Lundin and Doré, 2011;Lester et al, 2013;McIntosh et al, 2013). As pointed out by Lundin and Doré (2011), hyper-extension riftrelated processes may lead to significant weakening of the preorogenic lithosphere, thus playing a critical role on the reactivation and inversion of rifted margins.…”

Section: Rift Inheritance and Tectono-metamorphic Evolutionmentioning

confidence: 99%

Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Beltrando

Manatschal

Mohn

et al. 2014

Earth-Science Reviews

125

104

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Magma-poor rifted margins are being increasingly recognized in present-day Atlantic-type systems. However, findings of fossil areas floored by exhumed mantle or hyper-extended crust are comparatively rare within orogenic belts that were originated through the inversion of pre-existing rifted margins. This discrepancy may be due to the common reactivation of lithological contacts during subduction/orogeny, potentially masking pre-orogenic relationships, and, most importantly, to the frequent lack of a preorogenic layer-cake architecture, hindering retro-deformation of multiply deformed tectonic units. This study outlines a methodology to detect sections of magma-poor, hyper-extended rifted margins without a layer-cake architecture in multiply deformed/metamorphosed terrains. This approach is defined by comparison to well studied examples of fossil analogues preserved in weakly deformed parts of Alpine orogens. In the latter domains, continental basement and hydrated peridotites were exhumed at the basin floor during Jurassic rifting along long-offset detachment systems. Extensional geometries locally resulted in tectonic sampling of laterally discontinuous slivers of allochthonous continental basement and pre-rift sediments from the hanging wall blocks. Lithostratigraphic associations consisting of continental basement rocks directly juxtaposed with syn-to post-rift meta-sediments and/or serpentinized subcontinental mantle are widespread within sections of Alpine-type orogenic belts that underwent high-to ultra-high-pressure metamorphism. However, similar associations may arise from a variety of processes other than rift-related lithospheric thinning in magma-poor environments, including subduction mélange dynamics or deposition of sedimentary mélanges along convergent/divergent margins. The partial preservation of rift-related lithostratigraphic associations may still be assessed, despite the lack of biostratigraphic evidence, by (1) the consistency of the lithostratigraphic architecture over large areas, despite pervasive Alpine deformation, which rules out chaotic mixing during subduction/ exhumation, (2) the presence of clasts of basement rocks in the neighboring meta-sediments, indicating the original proximity of the different lithologies, (3) evidence of brittle deformation in continental basement and ultramafic rocks pre-dating Alpine metamorphism, indicating that they were juxtaposed by fault activity prior to the deposition of post-rift sediments, and (4) the similar Alpine tectono-metamorphic evolution of ophiolites, continental basement and meta-sediments. A re-assessment of basement-cover relationships in...

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Inversion of a hyper-extended rifted margin in the southern Central Range of Taiwan

Cited by 119 publications

References 23 publications

From convergent plate margin to arc–continent collision: Formation of the Kenting Mélange, Southern Taiwan

From convergent plate margin to arc–continent collision: Formation of the Kenting Mélange, Southern Taiwan

The continent–ocean transition at the mid-northern margin of the South China Sea

Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

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