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1 (a) Generalized tectonic map of the globe showing proposed regions of lithospheric delamination (references are given in the text). (b) Proposed lithospheric delamination model (migrating instability) where mantle lithosphere peels off from the crust (asymmetric removal).
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This chapter presents numerical and laboratory-based geodynamical models that explore the evolution of the lithospheric delamination-peel-away process. The numerical model results are used to approximate the surface subsidence-uplift and crustal deformation patterns along a north-south cross section through East Anatolia, orthogonal to the Arabia-E...
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... 1998], the Apennines [Channell and Mareschal, 1989;Chiarrabba and Chiodini, 2013], the Carpathians [Girbacea and Frisch, 1998;Houseman and Gemmer, 2007], the East Anatolian plateau [Ş engör et al., 2003, 2008Keskin, 2003Keskin, , 2007Göğ üş and Pysklywec, 2008a], and the Tibetan plateau [Bird, 1978;Harrison et al., 1992;Ren and Shen, 2008] (Fig. ...
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... different lithospheric removal mechanisms (e.g., dripping vs. delaminating) as referred in Göğ üş and Pysklywec [2008b]. Here, we adopt the term delamination to describe the specific process, as defined by Bird [1979] such that cold and dense mantle lithosphere slab can peel away from the crust as a coherent slice in a plate/slab-like manner ( Fig. 5.1b). Other styles of lithospheric removal, such as viscous Rayleigh-Taylor-type instability of the mantle lithosphere [e.g., Houseman et al., 1981] are valid processes, but we focus on the nature of the delamination (peel away) type removal under continents and accretionary ...
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... In this context, Figure 5.2 shows orogenic regions formed by large-scale accretionay prisms [adopted from Ş engör and Natal'in, 1996] as pre- sent-day analogues to eastern Anatolia. ...
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... is based on the arbitrary Lagrangian-Eulerian finite element technique and as such is useful for treating finite deformations, and for tracking boundaries (surface topography) and inter- nal particles (e.g., P-T paths) [Fullsack, 1995;Pysklywec et al., 2002;Göğ üş and Pysklywec, 2008a,b]. Figure 5.3 shows the initial setup of our delamination (NUMMODEL-1 and NUMMODEL-2) experiments. ...
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... the crust has a brittle Coulomb behavior with an internal angle of friction φ = 15° -2°. Both experiments, NUMMODEL-1 and NUMMODEL-2, have several modifications to start the delamination process. Namely, weak decoupling layers have been included with a viscosity of 5 × 10 19 Pa s, between a section of the crust and mantle lithosphere ( Fig. 5.3). The inclusion of a low-viscosity weak zone to initiate delamination may also be considered to be the weak lower crust emplaced between strong upper crust and the mantle lithosphere layers (i.e., jelly sandwich model interpreted for the rheological structure of litho- sphere) [Burov and Watts, 2006]. According to the seismic ...
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... inclusion of a low-viscosity weak zone to initiate delamination may also be considered to be the weak lower crust emplaced between strong upper crust and the mantle lithosphere layers (i.e., jelly sandwich model interpreted for the rheological structure of litho- sphere) [Burov and Watts, 2006]. According to the seismic interpretations by Chen and Molnar [1983] in the context Figure 5.3 Illustration of model setup for lithosphere delamination model including the dimensions, initial thermal conditions, material types, and density for crust, mantle lithosphere, and underlying sublithospheric mantle. ...
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... held at 25 °C and the bottom boundary is held at 1523 °C and the heat flux across the side boundaries is zero. The 350 °C Moho is based on estimates for the southern Sierra Nevada of California [Lachenbruch and Sass, 1977] as a region where delamination process has been postulated. The ini- tial temperature profile is the same in both experiments (Fig. 5.3). The numerical (width) × (depth) resolution is defined by 201 × 101 Eulerian nodes and 601 × 301 Lagrangian nodes. However, half of the Eulerian and Lagrangian elements are concentrated in the top 160 km in order to enhance the resolution in the ...
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... reference experiment, NUMMODEL-1, is repre- sented by the delamination of the mantle lithosphere from the overlying crust and its geodynamical evolution is given in Figure 5.4 with associated plots of surface topography and crustal thickness evolution. The model is intended to explore the surface and crustal deformation styles of lithospheric delamination process with imposed plate convergence (Vp = 3 cm/yr) to the right side of the lithospheric plate. ...
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... to the delamination style separation of the oce- anic lithosphere from the overlying accretionary prism in accordance with the plate collision [Ş engör et al., 2003;Keskin, 2003;Göğ üş and Pysklywec, 2008]. Figure 5.4a shows that the dense mantle lithosphere has been peeling away from the crust rapidly (in less than 3 m.y.) while upwelling of the hot and buoyant (less dense) sublithospheric (asthenospheric) mantle occurs under crust into the area vacated by the mantle litho- sphere. ...
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... mantle with the mantle lithosphere, together with the dynamic flow and the plate convergence, results in > 2 km of uplift surface topography. The negative surface deflection (~ −1 km) adja- cent to the topographic peak has developed due to the downward pulling of the hanging mantle lithosphere under the delaminating hinge position ( Fig. 5.4b). The crust is thickened > 10 km (with respect to 42.6 km at t = 0) above this hinge since the "slab pull" produced by the hanging slab inherently drives the crustal shortening and thickening. Across the high-elevation region, the crust thins to 40 km within the plateau gap likely due to the gravitational col- lapse of the previously ...
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... is not homog- enously distributed along the model space. By t = 7.0 m.y., a broader area of mantle lithosphere delaminates/peels away from the crust and the crust becomes entirely exposed to the hot sublithospheric mantle. Since slab detachment occurs under the delami- nating hinge, the surface depression is recovered to less than ~ −500 m ( Fig. 5.4b). The position of the surface depression has migrated near the model edge toward the opposite direction of the plate convergence velocity. Previous analogue modeling by Göğ üş et al. [2011] finds that the behavior of the delaminating slab is similar to the retreating ocean slab in which the trench position migrates in the reverse ...
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... asthenospheric mantle mantle lithosphere Vp = 3 cm/year t = 2.9 m.y. still considerably high (i.e., plateau elevation is more than 2 km), however, the crust has been thinned compared to its original thickness. Model predictions show that the imposed plate convergence is taken up on the edges of the plateau as the crust thickens to more than 55 km (Fig. ...
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... higher plate convergence velocity in the delamination process may be considered as an approxi- mation to the northward motion of the Indian Plate in which the uplift of the Tibetan plateau has been sug- gested to be driven by a combination of lithosphere delamination and plate-shortening processes [Bird, 1978;Harrison et al., 1992;Ren and Shen, 2008]. Figure 5.5a shows the geodynamic model evolution after t = 2.9 m.y. and at t = 7.0 m.y. ...
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... area of lithospheric gap was expected to develop by t = 2.9 m.y., the shortening caused by the plate conver- gence effectively delimited the "delamination space". For the same time, the maximum surface topography (~4 km) is 2 km more compared with the previous model, and most of the surface crust is now associated with positive surface elevation (Fig. 5.5b). The only localized surface subsidence (−1 km) is at the delaminating hinge where the partial break-off of the postdelaminating slab occurs. This hinge location, represented by lower elevation, developed as a response to vertical pull through the sinking slab. Model predictions show widespread crus- tal shortening/thickening along the ...
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... East Anatolian plateau is represented by 2 km high average elevation and is bordered by the Bitlis suture front to the south and the Pontide arc to the north ( Fig. 5.6a). Geological studies suggest that the plateau has attained its high elevation in the last 13 m.y. [Ş engör et al., 2003] about the same time as the presumed conti- nental collision between the Arabian and the Eurasian plates [Okay et al., ...
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... reconstructions by Ş engör and Kidd [1979] suggest that the high plateau is compensated by thick lithosphere following plate shortening. However, seismo- logical and petrological studies interpret that significant portions of the lithosphere have been removed beneath all of present-day East Anatolia (Fig. 5.6b, c). Specifically, P-wave tomography models [Al Lazki et al., 2004;Biryol et al., 2011], the Sn wave attenuation [Gök et al., 2007] [2015] shows that the litho- sphere-asthenosphere boundary beneath all of Anatolia does not go deeper than 80-100 km and this prediction is in good agreement with the mantle upwelling hypothesis. Moreover, the ...
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... the crustal thickness under the plateau was formerly suggested to be as much as 55 km [Ş engör and Kidd, 1979], however, receiver function work by Zor [2008], Ozacar et al. [2008], Vanacore et al. [2013], and integrated Pn analysis of Moho variation by Kömeç-Mutlu and Karabulut [2011] suggest relatively thinner crust under the plateau (40-50 km; Fig. 5.6c). Corroborating the seismological interpretations, synthesized petrological work by Pearce [1990] and Keskin [2003] indicates that the widespread distribution of young (last 13 m.y.) volcanics in East Anatolia originated through decompression melting of upwelling asthenospheric ...
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... on the recent and geological, geophyscial, and petrological observations, a slab steepening and break- off geodynamic hypothesis has been suggested by Ş engör et al. [2003] and Keskin [2003,2007] to account for all the anomalous tectonic features presented above (Fig. 5.7). According to the authors, the oceanic lithosphere sub- ducted underneath the Pontides in the north of the East Anatolian plateau until the Oligocene. Following this subduction, the closure of the Neo-Tethyan Ocean occurred and the stacking of East Anatolian accretionary complex developed. Based on the proposed scenario, the northward ...
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... occurred nearly 13-11 m.y. ago [Ş engör et al., 2003] in conjunction with the onset of magmatism in calc-alkaline chemistry around the Erzurum-Kars pla- teau (northern section of the plateau) [Keskin, 2003]. Both of these interpretations may be used as a critical time frame for the onset of the lithospheric instability that started about 13 m.y. (Fig. ...
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... Figure 5.8, we compare our modeled surface topog- raphy and crustal thickness variation results for t = 7.0 m.y. ...
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... plateau. Results from the modeling indicate that the peel away of the dense lithosphere (it is the oceanic lithosphere in this geologi- cal context) and plate convergence may cause surface uplift as a result of isostatic and dynamic effect of lith- ospheric removal comparable to the present-day average elevation of East Anatolia along 42°E (Fig. 5.8a). It has been suggested that East Anatolia emerged from sea level ~11 m.y. ago, a timescale similar to that of modeled delamination events. Note that the short-wavelength topographic features in the observed profile are related to geomorphologic processes not included in our models. The long-wavelength plateau uplift of eastern ...
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... factors may account for this. The models do not include material transformations that could result in removal of the lower parts of the thickened crust [Jull and Kelemen, 2001]. Also it is possible that anomalously thinner crust in the northern part of the Bitlis suture zone may be a result of post-removal of eclogitization of the lower crust ( Fig. ...
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... used a rectangular Plexiglas tank with 25 cm (width) × 55 cm (length) × 25 cm (depth) and the expri- ment was scaled as upper mantle depth model of foreland plate (pro-plate) collision/subduction beneath a hinter- land plate (retro-plate) (Fig. ...
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... s) [Espurt, et al., 2008;Guilliume et al., 2009] (Table 5.2). The 1.3 cm thick proplate mantle lithosphere is modeled by a Figure 5.7 Simplified geodynamic evolution of the eastern Anatolia region at t = 13, 10, and 2 m.y. to present [modified from Keskin, 2003[modified from Keskin, , 2007Ş engör et al., 2003, 2008. Newtonian viscous silicone putty (Rhodrosil Gomme, PBDMS + galena fillers) [Funiciello et al., 2004[Funiciello et al., , 2006Bellahsen et al., 2005]. ...
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... (LABMODEL-1), the density and viscosity of the foreland plate (proplate) mantle lithosphere are ρ ml = 1507 kg/m 3 and η ml = 3.5 × 10 5 Pa s, respectively (Table 5.2). The lower crust is modeled by glucose syrup (the same material as the sublithospheric mantle) to serve as a decoupling "weak layer" between the crust and the mantle lithosphere a (Fig. 5.9). The upper crust and retroplate lithosphere are made up of vis- cous silicone putty (Rhodrosil Gomme, PBDMS + galena fillers) of similar viscosity to the mantle lithosphere of the pro-plate but of lower density (Table 5.2). These materials were used to simplify the stratified temperature-dependent Earth rheological profile respect- ...
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... lithosphere subduction is initiated in the experiments by forcing downward the leading edge of the mantle lithosphere into the glucose to a depth of 3 cm with an angle of approximately 45° (Fig. 5.9). After this, the buoyancy of the slab drives the subduction dynamics as the piston drives the proplate toward the retroplate. Previous studies show that faster plate con- vergence is associated with advancing plate subduction, whereas slower plate convergence is associated with retreating plate subduction [Bellahsen et al., ...
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... (Table 5.2). The model begins with the subduction of the ocean plate into sublithospheric mantle at about 90° dip angle. By t = 8 min, the subducting slab reaches to the bottom of the Plexiglas tank and by t = 16 min, the subduction has evolved into the continental delamination as the dense mantle lithosphere peels away from the over- lying crust (Fig. 5.10a). The top view and the side view of the model photography suggest that the ~5 cm of mantle lithosphere is replaced with the light-colored sublith- ospheric mantle due to the delamination. The top view figure shows that the central part of the model is asso- ciated with more delamination than the edges of the mantle lithosphere because ...
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... delamination of the model progresses as the model evolves and by t = 33 min, about 10 cm of the mantle lithosphere delaminated from the upper crust (Fig. 5.10b). Again, this process is visible from the top view and side view photographs as the light-colored sublithospheric mantle intrudes beneath the convergent crust. At this time, 10 cm of the mantle lithosphere slab sinks into the mantle and flattens at the bottom of the tank. Although the plate convergence actively pushes the lithosphere to ...
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... tracked the surface topography evolution of LABMODEL-1 by using a laser scanning technique where the laser machine is placed on top of the experi- ment (near the camera). Figure 5.10c shows the surface elevation for t = 16 min and t = 33 min along the X-X′ cross section line. ...
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... t = 33 min, the surface topography is associated with a wider zone of uplift due to the lithospheric shortening induced by the imposed plate convergence (Fig. 5.10c). The subsidence (−0.2 cm) at the delamination hinge still persists at x = 26 cm. We note that the migration of sub- sidence has moved ~5 cm on the reverse direction of the plate convergence and this suggests that the subcrustal retreat (delamination) develops in conjunction with ...
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... the rest of the model parameters are left the same as the previous experiment. At the beginning, as in the previ- ous experiment, the mantle lithosphere subducts into the sublithospheric mantle at a high dip angle (70°-80°) and at t = 5 min, the subducted lithosphere hits the bottom of the box while it is also subducting beneath the retroplate (Fig. 5.11a). At t = 12 min, the ocean plate subduction still continues (an ocean basin still exists between two plates) as the slab has just reached the bottom of the tank. Unlike LABMODEL-1, the subducting slab does not roll back, rather the slab drapes forward under the retroplate. By t = 27 min, the plate collision occurred between the two ...
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... between two plates) as the slab has just reached the bottom of the tank. Unlike LABMODEL-1, the subducting slab does not roll back, rather the slab drapes forward under the retroplate. By t = 27 min, the plate collision occurred between the two plates and the proplate crust is partially decoupled from the crust and overthrusts onto the retroplate (Fig. 5.11b). This sug- gests that the delamination of the mantle lithosphere from the overlying crust did not have sufficient time to occur, instead the partial decoupling of the crust from the mantle lithosphere occurs and a piece of the crust accretes to the retro(hinterland)plate. This type of crustal stacking onto the overriding plate is ...
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... style of crustal accretion is termed flake tectonics by Oxburgh [1972]. Figure 5.11c shows the surface topography evolution (along X-X′ cross section) for LABMODEL-2 at times, t =12 min and t = 27 min. ...
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... the hinge zone. Detachment of this lithosphere changes the surface elevation variation near the delamination hinge or where the sinking slab is attached to the overlying crust [Göğ üş and Pysklywec, 2008a]. Our modeled surface topography at t = 7.0 m.y. is consistent with the profile of the present-day topography across eastern Anatolia at 42°E (Fig. 5.8a). Consequently, we attribute the anoma- lous plateau uplift in the region to the removal of the ocean lithosphere and slow plate shortening. Previous studies suggest that eastern Anatolia started to emerge from sea level ~11 m.y. ago and in the last 6-7 m.y. has experienced enhanced volcanic activity (with subduction and decompression ...
Citations
... Similar geodynamic interactions involving slab retreat, roll-back, or delamination have been proposed in other postcollisional continental extensional systems (e.g., Tirel et al., 2013;Chen et al., 2016;Roche et al., 2018). This process is thought to be the dominant mechanism in the evolution of metamorphic core complexes in the Anatolian-Aegean extensional province (e.g., Göğüş et al., 2017;Erkül et al., 2018). Konstantinou and Miller (2015) compiled post-Laramide regional structural, magmatic, metamorphic, and sedimentation trends around metamorphic core complexes along a N-S transect of the western United States (Fig. 10). ...
This Special Paper focuses on the evolution of the crust of the hinterland of the orogen during the orogenic cycle, and describes the evolution of the crust and basins at metamorphic core complexes. The volume includes a regional study of the Sevier-Laramide orogens in the Wyoming province, a regional seismic study, strain analysis of Sevier and Laramide deformation, and detrital zircon provenance from the Pacific Coast to the foreland between the Jurassic and the Eocene.
... Some petrological and geodynamic modeling studies favor slab steepening/peel-back of initially flat subduction and eventual break-off as the cause, suggesting it is required to explain N-S discrepancies in volcanic alkalinity (Bartol & Govers, 2014;Keskin, 2003;Şengör et al., 2008) and satisfy the 1-2 km plateau uplift (Göğüş & Pysklywec, 2008;Göğüş & Ueda, 2018;Memiş et al., 2020). Other geochronologic and geodynamic studies favor lithospheric removal/thinning in the form of gravitational instabilities developed during collision (Göğüş, Pysklywec, & Faccenna, 2017;Schleiffarth et al., 2018), advocating it is required to explain the rapid surface uplift and volcanism along plateau edges. Better constraints for lithospheric thickness and the presence of thermal or melt derived anomalies below central and eastern Anatolia may help discriminate between the two scenarios. ...
... Major resulting provinces include the Central and Eastern Anatolian Volcanic Provinces (CAVP and EAVP) within the Central and East Anatolian Plateaus (Figure 1a; CAP and EAP). The 2 km-high EAP, resembling the Tibetan Plateau (e.g., Şengör et al., 2003), is covered in 1 km-thick, dominantly 10 Ma to recent volcanic units (Göğüş, Pysklywec, & Faccenna, 2017;McNab et al., 2018;Reid et al., 2017). However, recent isotopic data show volcanism may have been active since 20 Ma (Memiş et al., 2020;Rabayrol et al., 2019;Schleiffarth et al., 2018). ...
... Central and eastern Anatolia each display a unique geochemical and lithospheric character that would imply separate geodynamic and geological evolutions (e.g., Göğüş, Pysklywec, & Faccenna, 2017;Göğüş & Ueda, 2018;Reid et al., 2017;Schleiffarth et al., 2018). Central Anatolian basement forms part of the continental Menderes Taurus tectonic unit (e.g., Okay & Tüysüz, 1999), whereas Eastern Anatolia is generally characterized as an accretionary prism (e.g., Keskin, 2003). ...
The Eastern Mediterranean captures the east‐west transition from active subduction of Earth's oldest oceanic lithosphere to continental collision, making it an ideal location to study terminal‐stage subduction. Asthenospheric‐ or subduction‐related processes are the main candidates for the region's ∼2 km uplift and Miocene volcanism; however, their relative importance is debated. To address these issues, we present new P and S wave relative arrival‐time tomographic models that reveal fast anomalies associated with an intact Aegean slab in the west, progressing to a fragmented, partially continental, Cyprean slab below central Anatolia. We resolve a gap between the Aegean and Cyprean slabs, and a horizontal tear in the Cyprean slab below the Central Anatolian Volcanic Province. Below eastern Anatolia, the completely detached “Bitlis” slab is characterized by fast wave speeds at ∼500 km depth. Assuming slab sinking rates mirror Arabia‐Anatolia convergence rates, the Bitlis slab's location indicates an Oligocene (∼26 Ma) break‐off. Results further reveal a strong velocity contrast across the North Anatolian Fault likely representing a 40–60 km decrease in lithospheric thickness from the Precambrian lithosphere north of the fault to a thinned Anatolian lithosphere in the south. Slow uppermost‐mantle wave speeds below active volcanoes in eastern Anatolia, and ratios of P to S wave relative traveltimes, indicate a thin lithosphere and melt contributions. Positive central and eastern Anatolian residual topography requires additional support from hot/buoyant asthenosphere to maintain the 1–2 km elevation in addition to an almost absent lithospheric mantle. Small‐scale fast velocity structures in the shallow mantle above the Bitlis slab may therefore be drips of Anatolian lithospheric mantle.
... Such a removal/thinning process that yields thin lithosphere and localized zones of high heat flow Girbacea & Frisch, 1998;Göğüş et al., 2016;Houseman & Gemmer, 2007;Knapp et al., 2005;Lorinczi & Houseman, 2009) most likely occurs due to the reactivation of orogenic activity (e.g., Matenco, 2017). According to recent geodynamic modeling work, the elevation (>1.5 km) in the SE Carpathians and the extension in the adjacent region (e.g., the normal fault-controlled Brasov Basin) might be explained by lithospheric delamination-a slab peeling away from the overlying crust (Göğüş et al., , 2017. It can be inferred from Göğüş et al. (2016) that the subsidence and crustal thickening in the Focsani foredeep basin are related to interpreted thermal and dynamic (mantle and lithosphere) forcing beneath the region. ...
Spectral variations of gravity and topography data show non‐isostatic compensation of elevation in the Southeast Carpathians that is consistent with our new residual topography calculations. Multi‐dimensional thermo‐mechanical models are created to consider a possible mantle flow component of the surface topography with varying temperature models and crustal configurations. The temperature anomalies derived from large‐scale P‐wave velocity anomalies and combined temperature model are estimated as input for the parametric numerical modeling experiments. Model results show that a surface uplift (up to ~ 1 km) develops in the southeastern Carpathians due to the rising hot upper mantle beneath the region. The upwelling flow is also in concordance with observations such as volcanism and enhanced surface heat flow in the region. Subsidence in the eastern part (0.5‐1 km over the Vrancea zone and the Focsani Basin) forms in relation to the down‐going Vrancea slab. The findings indicate the significant role of upper mantle structures on the present‐day anomalous topography related to proposed post‐collisional tectonics in the Southeast Carpathians.
... Similarly to other chains worldwide (e.g. Gogus et al., 2017 and references therein), geological, geophysical, and geochemical evidence suggests that the evolution of the Apenninc system is related to large-scale removal of the underlying lithosphere (e.g. Lort, 1971;Karner and Watts, 1983;Royden and Karner, 1984;Malinverno and Ryan, 1986;Patacca et al., 1990;Wortel and Spakman, 1992;Buiter et al., 1998;Doglioni et al., 1998;Faccenna et al., 2003;Scrocca et al., 2005;Pauselli et al., 2006 and references therein). ...
... Finally, this approach can be generalized to further investigate other chains whose behaviour is known to be similar to the Apennines (e.g. Royden and Karner, 1984;Gogus et al., 2017). ...
The discrepancy between the size of the Apenninic chain and the depth of the Adriatic foredeep is investigated using 2D flexural backstripping on well-constrained depth-converted cross sections in the Pescara basin (Central Italy). The procedure consisted of removal, uplift, unfolding and unfaulting of the Pliocene–Pleistocene foreland deposits to produce a palaeogeographic map of the basin at the end of the Messinian and to constrain sedimentary rates since the Miocene. Results are found to support the contribution of an external load to the foreland evolution together with the Apenninic chain load. The interplay of the two types of loads resulted in spatial and temporal variations of the foredeep evolution that are quantified by palaeogeographic maps and sedimentation rates obtained through backstripping. Results are interpreted as representing the effects of a southward-migrating wave linked to slab detachment beneath the Adriatic foredeep. This procedure can be useful to investigate similar problems on other chains worldwide.
Lower crustal flow in regions of post-orogenic extension has been inferred to explain the exhumation of metamorphic core complexes and associated low-angle normal (detachment) fault systems. However, the origin of detachment faults, whether initially formed as high-angle or low-angle shear zones, and the extension is symmetric or asymmetric remains enigmatic. Here, we use numerical modeling constrained by geophysical and geological data to show that symmetric extension in the central Menderes Massif of western Anatolia is accommodated by the crustal flow. Our geodynamic model explains how opposite dipping Gediz and Büyük Menderes detachment faults are formed by ∼40◦ footwall rotation. Model predictions agree with seismic tomography data that suggests updoming of lower crust beneath the exhumed massifs, represented as “twin domes” and a flat Moho. Our work helps to account for the genetic relation between the exhumation of metamorphic core complexes and low-angle normal faulting in both Cordillera and Aegean orogenic regions and has important implications on crustal dynamics in extensional provinces.
Stratigraphic, petrological and geophysical studies suggest that the Late Permian (~ 260 Ma) Emeishan Large Igneous Province in southern China may be formed by mantle plume activity. However, the plume impingement hypothesis remains controversial since interpretations based on volcano-stratigraphic analyses around plume induced domal uplift/inner zone suggest that the volcanism occurred under submarine environment rather than elevated sub-aerial (above sea level) conditions, usually associated with the dynamic topography effects of the ascending mantle plumes. Here, 2-D numerical and 3-D scaled laboratory (analogue) plume experiments are used to explore the coupled dynamics of plume-mantle-lithosphere interaction and their evolution of surface topography characteristics. Experimental results show that the initial (plume incubation) phase is characterized by rapid, transient domal uplift above the plume axis, subsequently, as plume head flattens, there is short wavelength topographic variation (ie. subsidence and uplift occurs synchronously) due to the shear stress imposed onto the base of the lithosphere and loss of gravitational potential energy. The surface depressions predicted by the plume models, next to the plume axial/inner/uplift zone, may explain the deposition of submarine volcanics at Lake Erhai, Dali in the western side and Xiluo and Daqiao in the eastern side, which may resolve the plume controversy for the formation of Emeishan Large Igneous Province. Notably, while experimental results from these two different techniques show some differences, (e.g much bigger plume head for the laboratory experiment), the overall characteristics of the predictions have robust similarities. For instance, the extension above the plume axis may explain the enigmatic cause of the Panxi rift system, in the middle of the inner zone where giant dyke swarms radiate from, and mafic magma underplatings in the lower crust has been described by seismological studies.
Stratigraphic evidence is used to interpret that the East Anatolian Plateau with 2 km average elevation today was below sea level ~20 Ma and uplift began in the northern part. The presence of voluminous volcanic rocks/melt production across the plateau—younging to the south—corroborates geophysical interpretations (e.g., high heat flow and lower seismic velocities) that suggest progressive removal of the slab subducting under the Pontides. Here, we conduct numerical experiments that investigate the change in the surface uplift as a response to slab peel‐back and potential break‐off processes under subduction‐accretionary complexes as well as continental lithosphere. Model results show similar types of tectonic behavior and magnitudes of uplift‐subsidence in both oceanic and continental removal processes, and they satisfactorily explain 1.5 km of plateau rise and a ~280 km wide asthenospheric upwelling zone beneath Eastern Anatolia over 18 Myr timescale. Parametric investigation for varying plate strength and convergence velocities show that such model parameters control the amount of surface uplift (1 to 3 km), the width of the asthenospheric upwelling zone, and the potential timing/depth of break‐off of the steepening/peeling slab. Experiments show that slab break‐off develops during the terminal phase, which may correspond to only a few million years ago. Therefore, the long wavelength plateau uplift and magmatism over the Eastern Anatolian‐Lesser Caucasus region since 20 Ma is controlled by progressive slab peel‐back and resulting mantle dynamics. The slab break‐off process (if it happened) has yet an indiscernible role.
