Slab Rollback Versus Delamination: Contrasting Fates of Flat‐Slab Subduction and Implications for South China Evolution in the Mesozoic

Dai, Liming; Wang, Liangliang; Lou, Da; Li, Zhong‐Hai; Huang, Dong; Ma, Fangfang; Li, Fakun; Li, Sanzhong; Yu, Shengyao

doi:10.1029/2019jb019164

Cited by 51 publications

(41 citation statements)

References 74 publications

(143 reference statements)

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“…Thus, we propose this anomaly to be a fossil fragment of the Nazca slab that was subducting steeply prior to the onset of flattening, indicating break-off from the leading edge of the current Nazca slab (Liu & Currie, 2016). Slab break-off during the slab flattening process is common in geodynamic models (e.g., Dai et al, 2020;Haschke et al, 2002;Liu & Currie, 2016. The conditions for slab break-off during the slab flattening process include fast trenchward migration of the overriding plate (high convergence rate) and a strong buoyancy contrast between either an oceanic plateau or aseismic ridge crust (here the JFR) and the normal thickness oceanic crust of an old slab (Haschke et al, 2002;Li et al, 2011;Liu & Currie, 2016.…”

Section: Slab Break-off: Transition From Steep To Flat Subduction?mentioning

confidence: 89%

Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion

Gao

Yuan

Heit

et al. 2021

Preprint

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A new seismic model for crust and upper mantle of the south Central Andes is derived from full waveform inversion, covering the Pampean flat subduction and adjacent Payenia steep subduction segments. Focused crustal low-velocity anomalies indicate partial melts in the Payenia segment along the volcanic arc, whereas weaker low-velocity anomalies covering a wide zone in the Pampean segment are interpreted as remnant partial melts. Thinning and tearing of the flat Nazca slab is inferred from gaps in the slab along the inland projection of the Juan Fernandez Ridge. A high-velocity anomaly in the mantle below the flat slab is interpreted as relic Nazca slab segment, which indicates an earlier slab break-off triggered by the buoyancy of the Juan Fernandez Ridge during the flattening process. In Payenia, largescale low-velocity anomalies atop and below the re-steepened Nazca slab are associated with the reopening of the mantle wedge and sub-slab asthenospheric flow, respectively. Plain Language SummaryTaking advantage of the abundant information recorded in seismic waveforms, we imaged the seismic structure of the crust and upper mantle beneath central Chile and western Argentina, where the oceanic Nazca slab is subducting beneath the South American plate. The subducted Nazca slab is almost flat at a depth of 100-150 km in the north of the study area below the Pampean region, where the Juan Fernandez seamount ridge is subducting as part of the Nazca slab. The slab steepens again in the south in the Payenia region. Our model reveals pronounced low-velocity anomalies within the Pampean flat slab along the inland projection of the Juan Fernandez Ridge, indicating that the Pampean flat slab is thinned or even torn apart. A high-velocity anomaly is imaged beneath the flat slab, representing a former slab segment that was broken off during the slab flattening process and was overridden by the advancing young slab. Our model suggests a causal relationship between the oceanic ridge subduction and the flat slab formation. In the Payenia region, the slab resteepening resulted in the re-establishment of the mantle wedge and induced hot mantle flow below the slab, which are characterized by low-velocity anomalies in the model.

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Section: Slab Break-off: Transition From Steep To Flat Subduction?mentioning

confidence: 89%

Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion

Gao

Yuan

Heit

et al. 2021

Preprint

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“…The SCB is characterized by widespread extensional basin and dome generation, voluminous magma intrusion, and associated polymetallic mineralization during the Cretaceous (Figures 1 and 5; Dai et al, 2020; Li, Zhang, et al, 2014; Wang & Shu, 2012). A comprehensive study of these data can help us reconstruct the Cretaceous tectonic evolution of the SCB.…”

Section: Discussionmentioning

confidence: 99%

“…The tectonic evolution of the South China Block (SCB) in the Cretaceous is characterized by widespread extensional basin and dome generation, voluminous magma intrusions and associated polymetallic mineralization (Figure 1; Deng, Wang, & Li, 2017; Deng & Wang, 2016; Li, Zhang, et al, 2014 and reference therein). Most researchers relate this process to the subduction of the Pacific Plate (e.g., Dai et al, 2020; Deng, Zhang, Fan, & Pérez‐Gussinyé, 2014; Li, Jiang, Zhang, Zhao, & Zhao, 2015; Li & Li, 2007; Pan et al, 2018; Shi, Dong, Zhang, & Huang, 2015; Wang, Fan, Zhang, & Zhang, 2013; Wang & Shu, 2012; Xu, Deng, & O'Reilly, 2003; Zhou, Sun, Shen, Shu, & Niu, 2006). During the Cretaceous, the subduction of the Pacific Plate changed the intracontinental topography, and various fission track (FT) thermochronological investigations of the apatite and zircon have indicated that the southwestern SCB experienced an intricate pattern of uplift and exhumation (Guo, 2004; Li, Wang, Tan, & Peng, 2005; Zhou, Gon, Shen, Xu, & Yang, 2005).…”

Section: Introductionmentioning

confidence: 99%

Cretaceous exhumation history of the southwestern South China Block: Constraints from fission‐track thermochronology

et al. 2020

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To detect the exhumation history of the southwestern South China Block (SCB), we performed fission track (FT) analysis on zircon and apatite grains in granitoid and sedimentary samples. From east to west, the study area includes the Yunkai Massif, Lingshan granitic belt, Shiwandashan Basin, and eastern margin of the Youjiang Basin. The granite sample of the Yunkai Massif has two peaks of 75 and 92 Ma for zircon FT dating. The Lingshan granitic belt samples yield zircon FT central ages from 135 to 132 Ma. The Permian bauxite samples of the Youjiang Basin yield zircon FT central ages from 109 to 93 Ma and display age peaks at~97-93 Ma. The Yunkai Massif granite sample has two peaks at 74 and 104 Ma for apatite FT dating, while the Lingshan granitic belt sample has two peaks at 81 and 111 Ma. The cooling paths of the Yunkai Massif sample started with an Early Cretaceous (~120-100 Ma) cooling event that brought the granitoids into the apatite partial annealing zone (PAZ). Through comparative studies, we suggest that the southwestern SCB underwent three periods of crustal uplift during~135-132,~111-92, and~81-74 Ma, respectively, which is consistent with the regional stratigraphic unconformity and crustal extension. Only the Yunkai Massif and Lingshan granitic belt were uplifted during~135-132 Ma. During 111-92 Ma, the southwestern SCB experienced crustal uplift, and the basal conglomerate began to deposit in the Shiwandashan Basin. Late Cretaceous uplifted occurred during~81-74 Ma, and the Yunkai Massif was uplifted throughout the Cretaceous. From 97 to 92 Ma, the Permian bauxite deposits in the Youjiang Basin were uplifted, which provided the basis of the later transformation to Quaternary bauxite.

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“…The oceanic mantle consists of 73 km of dry olivine (Hirth & Kohlstedt, 2004), and is compositionally lighter than the asthenosphere (ρAsthenosphere -20 kg/m³). The lithosphere is given an initial dip of ~15° to facilitate the initial flat slab stage (Van Hunen et al, 2004;Huangfu et al, 2016;Liu & Currie, 2016;Dai et al, 2020). A 12 km thick "ridge" (2800 kg/m³) of weak quartz (Ranalli, 1997) is placed along the dipping subduction interface to aid in subduction initialization.…”

Section: Methodsmentioning

confidence: 99%

Trench migration and slab buckling control the formation of the Central Andes

Pons¹,

Sobolev²,

Liu³

et al. 2022

Preprint

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The formation of the Central Andes dates back to ~50 Ma, but its most pronounced phase, including the growth of the Altiplano-Puna Plateau and pulsatile tectonic shortening phases, occurred within the last 25 Ma. The reason for this evolution remains unexplained. Using geodynamic numerical modeling we infer that the primary cause of the pulses of tectonic shortening and growth of Central Andes is the changing geometry of the subducted Nazca plate, and particularly the steepening of the mid-mantle slab segment which results in a slowing down of the trench retreat and subsequent shortening of the advancing South America plate. This steepening first happens after the end of the flat slab episode at ~25 Ma, and later during the buckling and stagnation of the slab in the mantle transition zone. The Intensity of the shortening events is enhanced by the processes that mechanically weaken the lithosphere of the South America plate, which were suggested in previous studies. These processes include delamination of the mantle lithosphere and weakening of the foreland sediments. Our new modeling results are consistent with the timing and amplitude of the deformation from geological data in the Central Andes at the Altiplano latitude.

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Slab Rollback Versus Delamination: Contrasting Fates of Flat‐Slab Subduction and Implications for South China Evolution in the Mesozoic

Cited by 51 publications

References 74 publications

Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion

Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion

Cretaceous exhumation history of the southwestern South China Block: Constraints from fission‐track thermochronology

Trench migration and slab buckling control the formation of the Central Andes

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