Atypical syn-collisional wedges at thrust fronts: Their tectonic and gravity-driven development, and interpretation-related controversies

Morley, C.K.

doi:10.1016/j.earscirev.2023.104663

Cited by 2 publications

(3 citation statements)

References 321 publications

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“…Although an accretionary wedge would not be expected to develop in an intra-oceanic subduction setting, accretion could occur as the arc begins to collide with a passive continental margin and these sediment were accreted (Draut & Clift, 2012). In this sense, the Palawan wedge represents an orogenic wedge (e.g., Morley, 2024) rather than a classic accretionary wedge that generates during the subduction of the oceanic crust in the lower plate. The wedge was developed by a combination of crustal shortening and gravitational collapse (Morley et al, 2023).…”

Section: Geology Offshore Palawanmentioning

confidence: 99%

“…The North Sabah wedge was characterized by the development of a serious of mini-basins with sediment thickness of 3-4 km (Morley et al, 2023). These mini-basins were proposed to be subsided by a combination of downbuilding and normal faulting driven by rapid sediment loading on the unstable, overpressured mudstone (equivalent of the Pagasa Formation) within the wedge (Morley, 2024;Morley et al, 2023). We argue against that the subsidence of the Isugod Basin was induced by the sediment loading on the wedge because there would be no overpressured mudstone (the Pagasa Formation) under the basin.…”

Section: Subsidence Of the Isugod Basin And Gravitational Collapse Of...mentioning

confidence: 99%

“…The presence of overpressured fluid-rich mudstones in the orogenic wedge was also proposed as a mechanism for the gravitational instability and collapse of the wedge and opening of syn-orogenic basins (Harris, 2011;Harris et al, 1998;Morley, 2024;Morley et al, 2023). For instance, the gravitational collapse of the Timor wedge can also be driven by lowering of the coefficient friction of the décollement at the base of the wedge as the décollement propagates into mud-rich units (overpressured mudstone) of the underthrust Australian continental margin (Harris, 2011;Harris et al, 1998), in addition to tectonic underplating.…”

Section: Subsidence Of the Isugod Basin And Gravitational Collapse Of...mentioning

confidence: 99%

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Evolution of Arc‐Continent Collision in the Southeastern Margin of the South China Sea: Insight From the Isugod Basin in Central‐Southern Palawan

Chen,

Yan,

Carter

et al. 2024

Tectonics

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The evolution of arc‐continent collision between the Palawan microcontinental block and the Cagayan Ridge in the southeastern margin of the South China Sea (SCS) is vital to understand how this collision correlated with seafloor spreading of the SCS. To address the evolution of arc‐continent collision, we studied the biostratigraphy and provenance of syn‐collisional sediments in the Isugod Basin in central‐southern Palawan. Microfossil analysis indicates a Late Miocene age (11.5–5.6 Ma) for the Isugod and Alfonso XIII Formations and rapid subsidence during initiation of the basin which may have been triggered by local extensional collapse of the wedge in response to forearc uplift. Multidisciplinary provenance analysis reveals that the Isugod and Alfonso XIII Formations were derived from the Middle Eocene–lower Oligocene Panas‐Pandian Formation on the Palawan wedge and the Late Eocene Central Palawan Ophiolite. These results suggest the emergence of both the orogenic wedge and obducted forearc ophiolite at ∼11.5 Ma, implying collision onset before ∼11.5 Ma. The collision initiation in Palawan could be better constrained to ∼18 Ma, based on the drowning of the Nido carbonate platform in the foreland. Therefore, the gravitational collapse of the Palawan wedge and the subsidence/formation of the Isugod Basin might reflect a significant uplift pulse in the hinterland of the wedge beginning within 13.4–11.5 Ma in the late stage of collision. It indicates that although compression originated from spreading of the SCS had ceased at 16–15 Ma, arc‐continent collision in Palawan did not stop and was sustained by compression from the upper plate afterward.

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Section: Geology Offshore Palawanmentioning

confidence: 99%

Section: Subsidence Of the Isugod Basin And Gravitational Collapse Of...mentioning

confidence: 99%

Section: Subsidence Of the Isugod Basin And Gravitational Collapse Of...mentioning

confidence: 99%

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Evolution of Arc‐Continent Collision in the Southeastern Margin of the South China Sea: Insight From the Isugod Basin in Central‐Southern Palawan

Chen,

Yan,

Carter

et al. 2024

Tectonics

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An Integrated Study of Age and Formation of the Aru Trough, Eastern Banda Arc, Indonesia: Implications for Seismic Hazards

Zhang,

Yang,

Mooney

et al. 2024

Tectonics

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The Banda Arc in eastern Indonesia has a complex tectonic history involving oceanic and continental subduction, arc‐continent collision and slab rollback. Among these the subduction rollback that began at 16 Ma shaped the regional tectonic configuration, causing notable upper plate extension evidenced by the Banda Sea and Weber Deep. However, the effects of subduction rollback on the lower plate remain less understood. The Aru Trough, part of subducting Australian continental margin, shows strong deformation and high seismicity, making it ideal for studying these effects. Utilizing multibeam bathymetry, seismic reflection profiles, GPS observations, seismicity and focal mechanisms, we investigate the crustal deformation, driving mechanisms and seismic risks in the Aru Trough under the background of Banda slab rollback. The Aru Trough shaped like an inverted triangle narrows from 160 to 40 km southward. It has a fast 53.8 mm/yr extensional rate at present, when combined with its maximum width suggesting a 3 Ma age. High‐angle faults (>60°) are present at its margins and interior. The trough has a high density of seismicity up to 5.9 events per 25 km2, with dominant normal and strike‐slip events, consistent with observed deformational patterns. The low seismic b‐value of 0.82 ± 0.01 suggests a high‐stress state with potential for strong earthquakes (Mw ≥ 6.5). Our findings indicate that lower plate deformation is profoundly influenced by subduction rollback, oblique arc‐continent collision and regional strike‐slip faulting. Understanding deformation in the Aru Trough is crucial for grasping the broader tectonic evolution of the Banda Arc and assessing seismic risks.

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Atypical syn-collisional wedges at thrust fronts: Their tectonic and gravity-driven development, and interpretation-related controversies

Cited by 2 publications

References 321 publications

Evolution of Arc‐Continent Collision in the Southeastern Margin of the South China Sea: Insight From the Isugod Basin in Central‐Southern Palawan

Evolution of Arc‐Continent Collision in the Southeastern Margin of the South China Sea: Insight From the Isugod Basin in Central‐Southern Palawan

An Integrated Study of Age and Formation of the Aru Trough, Eastern Banda Arc, Indonesia: Implications for Seismic Hazards

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