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Linking plate subduction and mantle dynamics in circum-Pacific margins

Dynamic topography is an important component of topography produced by mantle flow beneath the lithosphere. Like other components topography, dynamic topography sheds control on the eustacy, coastline evolution, source-to-sink systems, and long-wavelength variations in topography within continental interior far away from plate margins. In this aspect, dynamic topography has played a vital role in exploring the relationships between plate subduction, mantle flow, and Earth surface process. The circum-Pacific domain has been undergoing multiple re-orientations in subduction and given rise to basin-mountain systems in both eastern (western North America and South America) and western (East Asia) Pacific continental margins since late Mesozoic. Prominent diversity between the modern mantle structures of East Asia and the Americas strongly indicate different plate subduction history; this difference in evolution of the plate tectonics and mantle structure is recorded in dynamic topography. Fully unraveling the four-dimensional dynamic topography and its implications for tectonics has been one of the major challenges in both East Asia and the Americas. To help understand this complex relationship, we welcome your contributions addressing topics that concentrate on (1) the formation/origin and evolution of mantle architecture, (2) spatial-temporal evolution of Earth’s surface topography, especially dynamic topography, (3) evolution of basin-mountain systems and their indication of plate subduction, and (4) 4-D geodynamic models of eastern and western Pacific continental margins and the other regions since late Mesozoic.

Co-organized by TS7
Convener: Shaofeng Liu | Co-conveners: Michael Gurnis, Wei Leng, Simon Williams, Chengfa LinECSECS
Presentations
| Fri, 27 May, 08:30–09:50 (CEST)
 
Room -2.91

Fri, 27 May, 08:30–10:00

Chairpersons: Shaofeng Liu, Simon Williams

08:30–08:40
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EGU22-6749
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solicited
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Highlight
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Virtual presentation
Brian K. Horton

Variations in subduction configuration and mantle dynamics can be detected in retroarc foreland basins.  Modern and ancient examples from western South America show how discrete geodynamic mechanisms drive regional unconformity development in the Andean foreland basin.  Positive dynamic topography in the basin, fold-thrust belt, and broader convergent plate margin can be generated by (1) flat slab subduction, (2) slab window formation, (3) slab breakoff, (4) elevated intraplate (in-plane) stress, or (5) mantle flow variations.  A survey of long duration (>1–20 Myr) unconformities considers these and alternative mechanisms, including (6) local shortening-induced uplift in the frontal thrust belt and proximal foreland, (7) growth and advance of a broad flexural forebulge in the distal foreland, (8) uplift of intraforeland basement blocks along crustal-scale reverse faults, (9) tectonic quiescence with regional isostatic rebound, and (10) diminished accommodation or sediment supply due to changes in sea level, climate, erosion, or sediment transport.  These contrasting mechanisms can be readily observed in the modern foreland, particularly in the case of increased interplate coupling during active flat slab subduction and slab window generation associated with subduction of an active oceanic spreading ridge.  In the ancient record, the operative geodynamic mechanisms can be distinguished on the basis of the spatial distribution, stratigraphic position, paleoenvironmental context, and duration of foreland unconformities within the Cretaceous to Quaternary geodynamic framework of the Andean orogenic system.

How to cite: Horton, B. K.: Stratigraphic record of dynamic topography in the Andean foreland basin, South America, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6749, https://doi.org/10.5194/egusphere-egu22-6749, 2022.

08:40–08:45
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EGU22-10560
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Highlight
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Virtual presentation
Jonny Wu et al.

One of the greatest challenges of modeling the plate tectonic history of Earth during the Mesozoic and Cenozoic eras lies in reconstructing the Pacific Ocean and its predecessor ocean, Panthalassa.  A major reason for the plate tectonic uncertainty in this region is extensive subduction, which has consumed most (>95%) of the Pacific-Panthalassan ocean lithosphere formed since 150 Ma (Törsvik et al., 2019) and recycled it into the mantle, destroying the information on past plate motions recorded by seafloor magnetic lineations.  Consequently, many circum-Pacific margin plate tectonic models, including the popular GPlates models (e.g. Matthews et al., 2016; Müller et al., 2019), necessarily extrapolate 1000’s of km of subducted seafloor (i.e. synthetic seafloor isochrons).  Given the limited constraints, it is understandable that such models also prefer more straightforward solutions with a smaller number of larger plates, avoiding the complexities of modeling intra-oceanic subduction despite geological evidence from accreted circum-Pacific oceanic terranes.

Here we build the first topologically-closed, global plate tectonic model of the circum-Pacific using structurally-restored slabs from mantle seismic tomography as our primary constraint.  We use the numerical code TERRA to assimilate three variants of our ‘tomographic’ global plate model into mantle circulation forward models and assimilate the default GPlates model as a reference.  We show our preliminary geodynamic modeling results and test our model predictions against observed mantle structure, Earth’s geoid, and oceanic realm dynamic topography. 

All cases favor plate models that incorporate intra-oceanic subduction within Pacific-Panthalassa, particularly within the northern Pacific.  We find robust support for significant slab lateral advections (i.e. non-vertical slab sinking) under NW Pacific basin.  We discuss similarities and differences between our new ‘tomographic’ plate models and the GPlates model, which has been used for almost all geodynamic studies of the circum-Pacific to date. 

How to cite: Wu, J., Lin, Y.-A., Colli, L., Chen, Y.-W., Fuston, S., and Wu, T.-J. J.: First views from assimilation of a new ‘tomographic’ circum-Pacific plate reconstruction into mantle circulation models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10560, https://doi.org/10.5194/egusphere-egu22-10560, 2022.

08:45–08:50
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EGU22-5668
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ECS
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Highlight
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Virtual presentation
Jiashun Hu et al.

The Hawaiian-Emperor Seamount Chain changed its strike by 60° around 47 Ma, causing the Hawaiian-Emperor Bend (HEB). Both a change in Pacific Plate motion and a change in plume dynamics have been proposed to account for the HEB, but vigorous debates remain on their relative contribution. In order to have a better understanding, we build high–resolution global mantle convection models and test alternative plate reconstructions of North Pacific to quantify the contribution of each mechanism. For the contribution of Pacific Plate motion change, we find that Izanagi Plate subduction, followed by demise of the Izanagi–Pacific ridge and Izu–Bonin–Mariana subduction initiation alone, is incapable of causing a sudden change in plate motion, challenging the conventional hypothesis on the mechanisms of Pacific Plate motion change. Instead, with the alternative intra-oceanic subduction model, the Paleocene slab pull from Kronotsky subduction in North Pacific exerts a northward pull on the Pacific Plate, with its demise causing a sudden 30-35° change in plate motion. We further quantify the Hawaiian Hotspot drift using global mantle convection models with both the traditional and the alternative plate reconstructions. We find both models yield a fast southward drifting Hawaiian plume due to the push of slabs on the edge of the Pacific LLSVP. In the end, we discuss the combinational effects of Pacific Plate motion change and Hawaiian hotspot drift on the formation of HEB under different scenarios to gain insights on the possible history of North Pacific since the Late Cretaceous.

How to cite: Hu, J., Gurnis, M., Rudi, J., Stadler, G., Müller, D., and Zhang, J.: Quantifying the contributions of Pacific Plate motion change and hotspot drift to the formation of Hawaiian-Emperor Bend, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5668, https://doi.org/10.5194/egusphere-egu22-5668, 2022.

08:50–08:55
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EGU22-1896
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ECS
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Virtual presentation
Hamish Brown et al.

The tectonics of East and Southeast Asia are notoriously complex. Consisting of an intricate patchwork of microplates and accreted terrains, even the recent (i.e Cenozoic) tectonic history of the region remains controversial; and many differing reconstructions have been proposed. While the exact kinematics remain poorly constrained, it is generally accepted that the region has been characterised by a long history of subduction and downwelling. However, numerous geological and geophysical observations, at a first glance, appear to lie in stark contrast to this history. For example, regions of present-day dynamic uplift inferred from residual topography studies, the observation of seismically slow anomalies in numerous tomography models, and the widespread intraplate volcanism in East Asia since the latest Paleogene are all at odds with the expected cold upper mantle and downwelling associated with a history of subduction. Here, we propose a solution to this problem, in which hot asthenospheric material flows from the Pacific domain into East Asia—passing through the slab window opened by the subduction of the Izanagi-Pacific ridge during the early Cenozoic. To investigate this hypothesis, we compare several independent geological observations to the asthenospheric flow predicted by a suite of recently published 3D global mantle convection models.  Firstly, we compare observations linked to uplift and erosion to the changes in dynamic topography induced by this influx of hot material. These include the widespread late Eocene–Oligocene sedimentary hiatus in far eastern China and the regional erosion of southeastern China since the Miocene inferred from Apatite Fission Track Thermochronology (AFT) studies. Secondly, the timing and location of intraplate volcanism is compared with the predicted distribution of hot material through time. We find the westward influx of asthenospheric material to be a robust feature in the models, being predicted under all considered tectonic reconstructions.  Nevertheless, the influence of this material is significantly affected by differing implementations of the Philippine Sea Plate (PSP) history, which allows us to distinguish between these reconstructions based on their correlations with the evidence considered. A larger PSP is found to predict dynamic subsidence in regions where uplift and erosion is present, such as the East China Sea Shelf Basin and the Cathaysia Block, while also predicting large-scale mantle downwelling in regions where intraplate OIB-type magmatism has been recorded. A smaller PSP and the consequent existence of the hypothesised 'East Asian Sea' slabs instead allows the hot asthenospheric material to predominate over a larger region, providing a better fit to the spatial distribution of regional-scale erosional episodes and OIB-type magmatism.

How to cite: Brown, H., Colli, L., and Bunge, H.-P.: Asthenospheric Flow through the Izanagi-Pacific Slab Window and its Influence in East Asia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1896, https://doi.org/10.5194/egusphere-egu22-1896, 2022.

08:55–09:00
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EGU22-2130
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Virtual presentation
Yinbing Zhu et al.

A well-constrained plate deformation model may lead to an improved understanding of sedimentary basin formation and the connection between subduction history and over-riding plate deformation. Building quantitative models of basin kinematics and deformation remains challenging often due to the lack of comprehensive constraints. The Bohai Bay Basin (BBB) is an important manifestation of the destruction of the North China Craton, and records the plate kinematic history of East Asia during the Cenozoic. Although a number of interpretations of the formation of the BBB have been proposed, few quantitative basin reconstruction models have been built to test and refine previous ideas. Here, we developed a quantitative deformation reconstruction of the BBB constrained with balanced cross-sections and structural, stratigraphic, and depositional age data. Our reconstruction suggests that the basin formation process was composed of three main stages: Paleocene-early Eocene (65-42 Ma) extension initiation, middle Eocene-early Oligocene (42-32.8 Ma) extension climax, and post-Oligocene (32.8-0 Ma) post-extensional subsidence. The deformation of the BBB is spatially heterogeneous, and its velocity directions rotated clockwise during the basin formation process. The reconstruction supports the interpretation that the BBB formed via strike-slip faulting and orthogonal extension and that the basin is classified as a composite extensional-transtensional basin. We argue that the clockwise rotation of the basin velocity field was driven by the counter-clockwise rotation in the direction of Pacific Plate subduction. The kinematics of the BBB imply that the Pacific Plate may have been sufficiently coupled to the over-riding East Asian Plate during the critical period of Pacific Plate reorganization. The new reconstruction provides a quantitative basis for studies of deformation processes not only in the vicinity of the BBB but more broadly throughout East Asia.

How to cite: Zhu, Y., Liu, S., Zhang, B., Gurnis, M., and Ma, P.: Reconstruction of the Cenozoic deformation of the Bohai Bay Basin, North China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2130, https://doi.org/10.5194/egusphere-egu22-2130, 2022.

09:00–09:05
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EGU22-2715
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ECS
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Virtual presentation
Huizi Jian et al.

The back-arc marginal sea is a small ocean basin located between the volcanic arc and the continental crust. This area is not only an important gathering place for natural resources, but also an important place for plate interaction. Therefore, clarifying the origin and evolution of marginal seas can produce a huge boost for us to explore natural resources and improve the plate interaction mechanism. At present, the back-arc marginal sea with the largest opening rate of the Earth is the Lau Basin, and most marginal seas are generally in a state of medium-to-low-speed opening, such as the Mariana Trough, the Aegean Sea and the Caribbean Sea, and a small amount of marginal seas are even shortening, such as the Sea of Japan. What caused the marginal seas to open at different speeds?  In order to answer this question systematically and give a unified model for the origin and evolution of the marginal seas of the Earth, we must first figure out when the marginal sea will grow up. Therefore, we run 2-D and 3-D numerical experiments to test the possible effects of different factors on the evolution of the marginal sea. The results of our dynamic models can not only fit the evolution of the global marginal sea well, but also come to a robust conclusion: when the subducting plate stagnate in the transition zone, the opening rate of the marginal sea may decrease; but the marginal sea that stopped opening may still grow up again under special conditions. Furthermore, we explain the diversity of the current marginal sea evolution, which provides more theoretical foundations for the discipline of plate tectonics.

 

How to cite: Jian, H., Yang, T., and Guo, P.: When will the marginal sea grow up?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2715, https://doi.org/10.5194/egusphere-egu22-2715, 2022.

09:05–09:10
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EGU22-5762
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On-site presentation
Anouk Beniest et al.

 The Mangatolu Triple Junction (MTJ) and the Fonualei Rift and Spreading Center (FRSC) are two prominent bathymetric features in the northern Lau Basin in the southwest Pacific Ocean. We present the results of six W-E running Multi-Channel Seismic (MCS), magnetic and sediment echo sounding profiles acquired during the ARCHIMEDES-I expedition. These profiles cover the MTJ, the FRSC and the region just south of the FRSC to investigate the tectonic history and current tectonic activity of the Lau Basin. 

On all MCS profiles, we observe a heavily faulted basement on both sides of the MTJ and FRSC with faults that are covered with sediments, confirmed by the sediment echo sounding data. We consider these buried faults inactive today. We also observe faults that reach the seafloor. These faults are generally located closer to the MTJ and the FRSC and they correlate well with seismic activity recorded in the region. We thus consider these faults currently active. Seismically transparent bodies are observed on most profiles as well. We have interpreted those as volcanic intrusions, i.e. sills, or as volcanoes that pierce through the stratigraphy, especially closer to the volcanic arc. 

The two sets of faults, the notion that extension rates are higher at the MTJ (32 mm/yr) than at the southern tip of the FRSC (8 mm/yr) and the results from our newly acquired and interpreted magnetic data, have led to the interpretation that an earlier rift phase accommodated extension in a wide rift tectonic setting between 2.15 Ma and 0.85 Ma at the MTJ and 2.15 and 1.61 Ma at the FRSC. Today, the extension is accommodated in a narrow rift tectonic setting close to the MTJ and FRSC with a higher extension rate at the MTJ than at the southern tip of the FRSC. These findings suggest that the MTJ and FRSC are one, single intra-plate extension zone that is in the process of breaking apart the overriding Niuafo’ou-Tonga microplate along the MTJ and FRSC.

How to cite: Beniest, A., Schnabel, M., Barckhausen, U., Dannowski, A., Schmid, F., Riedel, M., Jegen, A., and Kopp, H.: Tectonic activity at Mangatolu Triple Junction and the Fonualei Rift and Spreading Center: breaking apart the intra-oceanic Niuafo’ou-Tonga microplate, Lau Basin, South West Pacific Ocean, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5762, https://doi.org/10.5194/egusphere-egu22-5762, 2022.

09:10–09:15
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EGU22-6764
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ECS
Menno Fraters et al.

The Cascadia Subduction Zone is characterized by young subducting lithosphere, its isolation from other subducting slabs, and its ability to produce megathrust earthquakes (M>9.0) and devastating tsunamis. Due to its high potential hazard and risk, it is also a well-studied subduction zone where modern, diverse and detailed observational datasets are available through the USGS and initiatives like GeoPrisms and EarthScope. These datasets include high quality GPS, onshore and offshore geophysical imaging, magmatic and seismic anisotropy data. These datasets present an opportunity to gain insight into slab structure, tectonic evolution, and present-day seismic hazards. Still, many questions remain about the physical processes that can self-consistently explain all the observations, and better estimate seismic hazards. For example, for the slab, geologic and geophysical data suggest that there may be one or two prominent slab gaps or tears, while tomographic data does not fully constrain the depth extent of the slab. Furthermore, the overriding plate is composed of several different terranes and contain numerous active and slowly moving faults, complicating efforts to accurately constrain variations in the overriding plate present-day stress and deformation rates.

In this study we test whether comparison of observations to model predictions can distinguish between different slab geometries for the Cascadia Subduction Zone. To this end, we have created regional 3D geodynamic models of Cascadia including the Cascadia slab based on the Slab 2.0 dataset. The model setup is built with the Geodynamic World Builder and, and the models are run using the mantle convection and lithospheric dynamics code ASPECT. During the evolution of these models we track the development of the CPO (Crystal Preferred Orientation), so we can compare it against seismic anisotropy data of the region. Our presentation will focus on the preliminary results of these models and demonstrate workflows for linking the model results to surface tectonics.

How to cite: Fraters, M., Billen, M., Naliboff, J., Staisch, L., and Watt, J.: Exploring the Cascadia slab structure coupling 3D thermomechinal and CPO modeling., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6764, https://doi.org/10.5194/egusphere-egu22-6764, 2022.

09:15–09:20
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EGU22-6782
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ECS
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Virtual presentation
Meng Zhou et al.

It is widely accepted that the subduction system along an active continental margin has significant impacts on continental motions and deformation. The longest strike-slip fault in East Asian, the Tan-Lu Fault extends through the lithosphere and parallels the East Asian margin trench could be recognized as weak zone and left more significant geological information of plate tectonics than surrounding areas ( Collettini et al., 2019 ). Previous studies have gained some common sense about the motion of the East Eurasia continent margin from the Tan-Lu fault in the Late Mesozoic. The Tan-Lu fault experienced two phases sinistral strike-slip motion under compression with a striking-length about 150~200 km ( Zhu et al.,2005, 2009; Zhao et al.,2016 ), one stage is the Late Jurassic of the obtained age of 162~150 Ma and the other stage is the Early Cretaceous of the gained age of 143Ma~132Ma ( Zhu et al.,2005, 2010, 2018; Zhang and Dong, 2008 ). However, the formation mechanism of the large strike motion is still in doubt. Zhu et al., (2018) suggest that the Mesozoic tectonism of the Tan-Lu fault zone is dominated by paleo-Pacific plate subduction and thus can reflect its subduction history, while some others think the geodynamics of the Tan-Lu fault is controlled by the combined influences of the collision between the Tibetan blocks and Eurasia and the paleo-Pacific plate subduction ( Zhang et al., 2010 ).

 

To understand whether the paleo-Pacific subduction could have a dominant impact on the tectonic activities along the Tan-Lu fault and how does it influence the overriding plate, we perform 3-D numerical simulations of oceanic-continental subduction with a weakened fault zone simulating the Tan-Lu Fault. The results indicate that the motion and deformation of the East Asian continental plate can be strongly influenced by the interaction between the paleo-Pacific plate and East Asia, especially by the coupling degree between the subduction plate and the overriding plate. The coupling degree could significantly improve when there is micro-continent from subduction plate collide with overriding plate and the overriding plate would undergo compression. The collision between micro-continents with East Eurasia continent in Late Jurassic and Early Cretaceous has been observed ( Li et al.,2020; Charvet,2013 ). From the plate reconstructions ( Müller et al.,2016 ), in the Late Mesozoic had a northward component with an average velocity 40~50 mm/yr. In our numerical model, the generation of large sinistral strike-length could explained by strong coupling caused by collision of micro-continents with Eurasia plate.

How to cite: Zhou, M., Yang, T., Deng, L., and Guo, P.: Strike-slip motion in the Late Mesozoic on the East Asian continental margin: Insight from 3-D numerical models with the Tan-Lu fault, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6782, https://doi.org/10.5194/egusphere-egu22-6782, 2022.

09:20–09:25
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EGU22-7368
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Virtual presentation
Danya Zhou et al.

The spatial and temporal variations of basin subsidence could potentially provide critical information for investigating the history of orogeny and deep mantle processes. However, due to the complexity of the formation mechanism of the Western Interior Basin, the factors controlling the basin subsidence has long been debated. Here, by reconstructing a high-resolution chronostratigraphic framework for the Upper Cretaceous strata and restoring the subsidence history of the basin, we analyze the control of the Sevier and Laramide orogenies on the Late Cretaceous evolution of the basin in the Wyoming-Utah-Colorado, and reveal the contemporary migration pattern of long-wavelength dynamic subsidence. During Cenomanian to Santonian time, thrusting events were active on the western margin of the basin, along which NS-trending long-wavelength subsidence center developed. By early Campanian (ca. 82 Ma), thrusting events developed into NW trend, and the center of long-wavelength subsidence shifted in the same orientation and gradually migrated to the center of the basin. Starting in the Maastrichtian (ca. 72 Ma), the NW-trending thrusting events migrates northeastward, roughly consistent with coeval long-wavelength subsidence center. Our results show that the former thrust event is related to Sevier orogeny, while the latter should be related to the Laramide orogeny. The initial timing of the Laramide deformation could start at as early as 82 Ma. This finding suggests that migrations of both long-wavelength subsidence center and Laramide deformation are driven by changes of Farallon subduction direction from eastward to northeastward and subduction angle from deep to flat. Our work shows how the subsidence history precisely records the timing and trajectory of Sevier and Laramide orogenies and dynamic topography, providing valuable insights for future three-dimensional modeling of dynamic subsidence in the Western Interior Basin.

How to cite: Zhou, D., Liu, S., Wang, L., and Wan, N.: Late Cretaceous Sevier and Laramide orogenies in Wyoming-Utah-Colorado, USA: Insight from basin subsidence history, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7368, https://doi.org/10.5194/egusphere-egu22-7368, 2022.

09:25–09:30
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EGU22-11229
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ECS
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Virtual presentation
Bo Zhang et al.

The kinematics of plate tectonics, deformation, and dynamic topography are strong indicators of coupling between plates and the mantle. East Asia is characterized by the presence of an unusually large horizontal slab that lies within the mantle transition zone. How this feature evolved and is linked to plate tectonics, deformation, and topography is poorly understood. Here, we show four-dimensional geodynamic modeling results constrained by a new deforming plate reconstruction that fits mantle architecture inferred from seismic tomography. We find that the subducted western Pacific slab was progressively torn by the Philippine Sea plate rotating clockwise during the Miocene and that northwestward mantle flow contributed to shaping the horizontal slab during subduction, leading to dynamic subsidence along the East Asia margin. The rather subdued change in dynamic topography, predicted from those models that fit the horizontal slab in the mantle, is consistent with the variation in residual topography, recorded in the stratigraphy, within only about +/- 200 m over the last 50 Myr during a period of no large marine inundation or retreat. The tectonics and topography of East Asia strongly contrast with those of Southeast Asia and are reflective of slabs ephemerally stagnating in the mantle below East Asia while avalanching into the lower mantle below Southeast Asia.

How to cite: Zhang, B., liu, S., Ma, P., and Gurnis, M.: The Horizontal Slab Beneath East Asia and Its Subdued Surface Dynamic Response, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11229, https://doi.org/10.5194/egusphere-egu22-11229, 2022.

09:30–09:35
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EGU22-13356
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ECS
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Virtual presentation
Chengfa Lin et al.

Decoding tectonic and climatic signatures from continental successions has become important in basin analysis. However, tectonic and climatic signatures can still be difficult to discriminate from each other. The late Mesozoic Xuanhua basin in the western Yanshan fold‑and‑thrust belt represents a representative intramontane basin and allows detailed stratigraphic, sedimentological, and provenance analyses. The work entailed an analysis of alluvial fan, fluvial, lake‑delta, and lacustrine systems in the Tuchengzi Fm. Lateral correlation of sedimentary columns reveals two large‑scale upward‑coarsening cyclothems each 80-240m thick, with prominent vertical changes from lacustrine through deltaic and fluvial to alluvial fan deposits. Two intervals of thrust‑related growth strata identified in the Tuchengzi Fm suggest that the cyclothems were controlled by tectonic uplift and accommodation change related to the Likouquan and the Mapu thrusting. In the lower upward‑coarsening cyclothem, stacking of small‑scale (3-16 m thick) upward‑fining cyclothems was revealed and argued to have been generated by alternating wet‑dry cycles. The wet half‑cycle started with discharge and deposition of flood‑generated mass‑flows into the lake and ended with accumulation of lacustrine mudstones as lake level rose. The lake deposits include the maximum flooding during the wet half‑cycle. The dry half‑cycle was characterized by continued lacustrine deposits, but with increased evidence of subaerial exposure indicated by rooting, paleosols and mudcracks resulting from falling of the lake level under dry conditions.

How to cite: Lin, C., Liu, S., and Steel, R.: Tectonic and climatic controls on the Late Jurassic-Early Cretaceous stratigraphic architecture of the Xuanhua basin, North China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13356, https://doi.org/10.5194/egusphere-egu22-13356, 2022.

09:35–09:40
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EGU22-13514
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ECS
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Virtual presentation
Bo Zhang et al.

The basin is an essential window for exploring tectonic evolution, which preserves the information of regional extension, subsidence, uplift, and denudation. The Jiaolai Basin, located on the northern the Sulu Orogenic Belt, records the extension events of East Asia and the post-orogenic evolution of the Sulu Orogenic Belt during the Cretaceous. Multiple provenance analyses were used in the study to reconstruct the source-to-sink system of the Laiyang Group in the Jiaolai Basin. The results show that the Jiaolai Basin has a two-stage evolution history. In the early Early Cretaceous (ca. 135-122Ma), the Zhucheng sag and Gaomi sag in the south developed firstly. Subsequently, in the late Early Cretaceous (ca. 121-113Ma), the Laiyang Sag in the north developed. Moreover, these sags undergone independent, multi-stage source-sink system evolution in their early stages, and shared similar provenance supply systems at the end of Laiyang Group (ca. 113Ma). The provenance analysis results show that at ~121 Ma, ultra-high pressure (UHP) rock undergone a rapid exhumation in the northern section of the Sulu orogenic belt, whereas, for the southern section, The UHP may not be exposed until ca.113Ma. The two-stage extension in Eastern Asia with the change in direction and magnitude, recorded in the Jiaolai basin, suggests the trench retreat and subduction direction Change of the Izanagi plate should be the first-order drive force of the extension events of Eastern Asia during the Cretaceous. Our results indicate that the change of the Izanagi subduction direction may be ~121 Ma.

How to cite: Zhang, B., Liu, S., Lin, C., and Ma, P.: Two-stage rifting of Jiaolai Basin, Eastern China, decoding from the source-to-sink reconstruction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13514, https://doi.org/10.5194/egusphere-egu22-13514, 2022.

09:40–09:45
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EGU22-13548
Tectonic and eustatic control of Mesaverde Group (Campanian-Maastrichtian) architecture, Wyoming-Utah-Colorado region, USA
(withdrawn)
Keith Minor et al.
09:45–09:50
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EGU22-13552
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ECS
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Virtual presentation
Neng Wan et al.

The Jurassic Ordos basin is generally considered an intracontinental basin characterized by rapid subsidence rate along western margin and slow subsidence rate within basin interior. However, the formation mechanism of Ordos basin was not yet well understood. Flexural backstripping of stratigraphic record spanning from 174-153Ma, along three well sections perpendicular to the western margin of Ordos basin clearly demonstrates that there were long wavelength anomalous subsidence components, termed residual subsidence, in addition to those induced by thrust loads and sediment loads. Flexural components exhibit similar spatial and temporal trends along three sections. Simulations demonstrates that the foredeep is only 80-100 km wide, corresponding to effective thickness of 15-20 km. Contribution by flexural component relative to cumulative subsidence decreases from 50-60% to -15% within foredeep from thrust front towards basin interior, while residual subsidence could account for 40-50% of cumulative subsidence for areas outboard extent of foredeep. From 174-153 Ma, residual subsidence increases from ~150 m to ~330 m, ~200 m to ~390 m, ~180 m to ~480 m in southern, middle and northern section respectively. Our results indicate that thrust loads could act as the dominant driver for subsidence of foredeep while other mechanism needs to be raised to explain the basin-wide anomalous residual subsidence. The general agreement regarding both magnitude and trends along all three sections between dynamic topography predicted by geodynamic models and residual subsidence separated from flexural modeling, indicates that the anomalous subsidence component might be of dynamic origin, related to subduction of paleo-Pacific plate initiated from latest Early Jurassic.

How to cite: Wan, N., Liu, S., Liu, G., and Li, X.: Dynamic origin of anomalous subsidence of Jurassic Ordos basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13552, https://doi.org/10.5194/egusphere-egu22-13552, 2022.