Continental collisions commonly involve highly curved passive plate margins, leading to diachronous continental subduction during trench rollback. Such systems may feature back-arc extension and ophiolite obduction postdating initial collision. Modern examples include the Alboran and Banda arcs. Ancient systems include the Newfoundland and Norwegian Caledonides. While external forces or preexisting weaknesses are often invoked, we suggest that ophiolite obduction can equally be caused by internal stress buildup during collision. Here, we modeled collision with an irregular subducting continental margin in three-dimensional (3-D) thermo-mechanical models and used the generated stress field evolution to understand resulting geologic processes. Results show how tensional stresses are localized in the overriding plate during the diachronous onset of collision. These stresses thin the overriding plate and may open a back-arc spreading center. Collision along the entire trench follows rapidly, with inversion of this spreading center, ophiolite obduction, and compression in the overriding plate. The models show how subduction of an irregular continental margin can form a highly curved orogenic belt. With this mechanism, obduction of back-arc oceanic lithosphere naturally evolves from a given initial margin geometry during continental collision.The formation of highly curved orogenic belts is still debated (Rosenbaum, 2014). Proposed mechanisms include processes associated with deformation along thinned fold-and-thrust belts (Marshak, 1988), gravitational spreading (e.g., Edey et al., 2020), or along-strike migration rate variations of plate boundaries (Rosenbaum and Lister, 2004). The latter includes processes such as plate rotation, trench rollback, or indentation during continental collision (Rosenbaum, 2014; Rosenbaum and Lister, 2004).The Alboran and Banda arcs are two modern systems that are associated with trench rollback and diachronous continental subduction along strike (Spakman and Hall, 2010; van Hinsbergen et al., 2014). Both regions experienced trench rollback against a highly nonlinear passive margin (see Fig. 1), where continental lithosphere subducted diachronously along the trench (Pownall et al., 2016; Spakman and Hall, 2010; van Hinsbergen et al., 2014). In the Banda region, continental material initially (15 Ma) subducted at Seram (Spakman and Hall, 2010), coinciding with trench rotation, and this was followed by continental subduction (4 Ma) at Timor, in the south (Fig. 1A). Oceanic subduction is now ceased, with collision occurring along the entire continental margin. The tectonic history of the Alboran Basin in the western Mediterranean is debated (van Hinsbergen et al., 2014). Most models agree that the slab retreated westward into the narrowing Alboran embayment since 30–20 Ma (Fig. 1B).Both regions share puzzling geological features, such as extensional basins in the upper plate (Pownall et al., 2016; Watts et al., 1993), and exhumed subcrustal continental lithosphere (Frasca et al., 2017; Gueydan et al., 2019; Pownall et al., 2014). The Banda system involves ophiolite obduction (Ishikawa et al., 2007), but this has not been identified in the Alboran arc. The world's largest subcontinental mantle exposures, the Ronda and Beni peridotites in the Alboran arc (Gueydan et al., 2019), have been suggested to have been exhumed by gravitational collapse after slab break-off (Platt and Vissers, 1989; Van der Wal and Vissers, 1993), by thrusting of an older Jurassic rifted margin (Tubia et al., 2009), or by hyperextension of the overriding plate before, and thrusting during, continental collision (Frasca et al., 2017; Gueydan et al., 2019; see Fig. 1C). It is unclear in these examples how the geologic evolution is linked to the highly arcuate geometry and irregular shape of the subducting continental margin, if at all.The aim of this study was to examine evolving plate stresses during irregular continental subduction and the formation of curved orogenic belts, to provide a better understanding of the drivers and controls of the geologic evolution. We show that localized tensional stresses during the initial stages of irregular margin collision cause short-lived back-arc rifting or spreading centers that are rapidly inverted once continental subduction spreads along the trench.We investigated the stress regime evolution during continental collision with an irregular margin (Fig. 2) in a model space of 3300 by 3960 by 660 km in size. The finite element code Citcom (Moresi et al., 1996; Zhong et al., 2000; Magni et al., 2014) solves the conservation equations for momentum, energy, mass, and composition. We used a visco-plastic rheology including diffusion and dislocation creep, lithospheric yielding, and an upper-limit viscosity (Magni et al., 2014; van Hunen and Allen, 2011). We did not apply external forcing; all dynamics were driven by internal buoyancy forces. Subducting and overriding plates were separated by a weak zone and decoupled from neighboring plates by weak transform faults to permit toroidal mantle flow (van Hunen and Allen, 2011; Magni et al., 2014). Continental lithosphere was free to move toward the trench and collide with the overriding plate as the intervening oceanic basin closed. The continental crust was initially 40 km thick; the underlying mantle lithosphere extended from 100 km depth close to the trench to 150 km in the far-field area to mimic the thicker plate interior (Fig. 2B). The subducting passive margin included an oceanic embayment of (along-strike) width wb and breadth (here used for the across-strike width) bb, with flanks that sat at an angle α with respect to the convergence direction. To study the impact of this embayment on the evolving stress distribution, we varied the initial width (between 600 and 1200 km) and breadth (between 300 and 700 km) while keeping the flank orientation angle α constant. The convergence-parallel stress field, σxx, was computed to investigate the stress localization that could be responsible for the observed normal or thrust faulting.Figure 3 depicts the model evolution of a subducting continent including an oceanic embayment wb = 1000 km by bb = 600 km. Initially, negative buoyancy of the oceanic slab drives subduction, trench rollback, and uniform extension in the overriding plate in all models (Fig. 3A). Initial continental subduction at the sides of the embayment locally reduces subduction velocities, and trench retreat stops (Fig. 3B). Trench retreat continues, however, at the oceanic embayment on the passive margin. With the local onset of continental collision (Fig. 3B), stresses start to vary significantly along the trench and upper plate. There is localized compression in collision regions, while extension close to the oceanic embayment continues to exert slab pull and trench retreat. The differential stresses cause yielding and rupture of the overriding plate. Opening of a back-arc spreading center (Fig. 3C) briefly increases convergence velocities by a factor of three (Fig. 4A). Shortly (∼5 m.y.) after onset of back-arc spreading, the oceanic embayment is completely subducted, and this is followed by continental subduction (Figs. 3D–Fig. 3F). At this point, the young oceanic back-arc basin measures only 166 km in ridge-perpendicular spreading distance (Fig. 3D). High continental crustal buoyancy reduces subduction velocities and stops trench rollback (Fig. 4A). Without local, rapid trench rollback driving the extensional stresses in the back-arc area, back-arc spreading ceases, and its stress state changes from an extensional to a compressional stress state within 10 m.y. after initial collision (Figs. 3E and Fig. 3F). During this last stage, slab break-off along the entire subducted margin ends subduction and allows the subducted continent to begin exhumation.Subduction of smaller embayments (Fig. 4B) does not rupture the overriding plate to produce back-arc spreading, but it still thins the overriding continent; crustal thickness reduces from the initial 40 km to as little as 8 km (Fig. 4B; Fig. S1 in the Supplemental Material1) at the onset of collision. The embayment breadth, bb, determines the duration of the overriding plate extensional phase, and hence the presence or absence of an oceanic back-arc basin. Too narrow embayments (small wb) do not create sufficient tensional stresses, while the widest embayments (wb = 1200 km) lack the required stress localization. When a back-arc spreading center is formed, its spreading duration varies from 1 m.y. in the smallest basin, to 5 m.y. (reference model, Fig. 3), to 10 m.y. in the models with the largest embayments (wb = 1200 km and bb = 600 km) and forming the largest back-arc basin (253 km cross-spreading distance).Subduction of an irregular passive margin allows formation of curved orogenic belts and a two-stage stress evolution from extensional to compressional states in the overriding plate during collision. Our models show how localized thinning or rupturing of the overriding plate occurs during local initial collision, while oceanic subduction continues elsewhere. Stress inversion and compressional deformation take place in a second stage, during full continental subduction. Such features are probably common in collision zones, given the naturally irregular shape of passive margins (Dewey and Burke, 1974).Many numerical models of continental collision have focused on linear passive margins (Schliffke et al., 2019; van Hunen and Allen, 2011) or oblique collision (Bottrill et al., 2014) to study slab break-off and exhumation of subducted continental crust. Compressional stresses and resulting topography during continental collision are controlled by plate coupling (Faccenda et al., 2009), rheological flow laws (Pusok et al., 2018), and buoyancy ratios and convergence velocities (Pusok and Kaus, 2015). Also, lateral compositional variations along strike on the subducting plate can trigger the formation of back-arc spreading centers (Magni et al., 2014; Menant et al., 2016), under the precondition of nonlinear rheology (Pusok et al., 2018). Our models combined these approaches and showed that the resulting stress inversion from extensional to compressional states in the back-arc basins is similar to sequences proposed for the obduction of ophiolites (Cawood and Suhr, 1992) or hyperextended continental margins (Gueydan et al., 2019). Previous modeling of ophiolite formation (e.g., Duretz et al., 2016; Hässig et al., 2016) typically prescribed a “thermal anomaly” (Duretz et al., 2016) or hot mantle upwelling (Hässig et al., 2016) close to a continental-oceanic margin to create a weak discontinuity. Shortening from far-field forcing then would lead to continental subduction at the weak discontinuity and emplacement of ophiolites on the continent. Our work suggests that such external factors are not necessarily required, since collision generates the weakening and compressional stresses in the back-arc area that are needed for the observed ophiolite obduction and crustal exhumation.The interface between upper and lower plate in our models is a constant viscosity weak zone: This determines stress transfer between the two plates (Hassani et al., 1997; Faccenda et al., 2009). During the transition from subduction to collision, this coupling is likely to change (Luth et al., 2010). Lower fluid and melt percolation (Faccenda et al., 2009) or low sedimentation rates increase coupling (Burov and Toussaint, 2007) and may transfer compressional stresses into the back-arc area more efficiently than in our models. If so, the timing and degree of compressional stresses of the back-arc area in our models would be underestimated; i.e., a faster and stronger transfer of stresses should occur in nature. In contrast, too high plate coupling would end shortening and cause regional forearc uplift (Luth et al., 2010), with no shortening in the back-arc area.Observations in the Banda and Alboran systems validate the sequence of stresses and processes predicted by our models (Gueydan et al., 2019; Spakman and Hall, 2010; van Hinsbergen et al., 2014; see Fig. 1C). Trench rollback into the Banda arc caused lateral arc-continent collision and synchronous opening of the extensional Weber Deep Basin (Pownall et al., 2016; Spakman and Hall, 2010). Subcrustal mantle lithosphere is thrusted at corners of the recent extensional basin (Pownall et al., 2014), where our models predict thinned crust and the most rapid change from extension to compression. In the Alboran arc, there is a high-velocity body along the entire arc subsurface, interpreted as a continuation of the peridotite at Ronda and Beni (Gueydan et al., 2019). A process of rifting by localized tensional stresses close to the trench during rollback (Fig. 1C), followed by compression and thrusting during continental subduction, has been suggested to trigger hyperextended continental margin obduction (Gueydan et al., 2019). In the Alboran arc, trench rollback rates have reduced from rapidly retreating (up to 8 cm/yr) during narrowing of the slab (van Hinsbergen et al., 2014) to subduction cessation coinciding with subduction of continental crust along the entire trench. Our models showing the highest retreat rates during narrowing of the oceanic basin followed by subduction cessation with full continental collision (Fig. 4A) fit these trends.Diachronous continental subduction has further been suggested to have formed young back-arc ophiolites by thrusting onto a continental margin during large-scale continental collision in the Caledonide orogen (Cawood and Suhr, 1992; Slagstad and Kirkland, 2018). During Baltica-Laurentia collision, diachronous initial collision in Newfoundland (Cawood and Suhr, 1992) and Norway (Slagstad and Kirkland, 2018) coincided with extension, as shown by mafic layered intrusions and ophiolite creation, while obduction is dated ∼15–20 m.y. later. With the onset of back-arc spreading predating continental subduction along the entire trench by ∼5 m.y. and predating compression in the back-arc area by ∼20 m.y. in our models, we estimate obduction within the period of 5–20 m.y. of back-arc formation, similar to the observations. The limited (trench perpendicular) ophiolite size (<100 km) in the Norwegian Caledonides and Newfoundland hints that the newly formed spreading center must have been small during onset of collision, and the spreading center was close to the main suture where the back-arc obducted.In conclusion, collision of a continent with an irregular passive margin not only can form highly arcuate orogenic belts, but it can also cause complex geological processes in the overriding plate resulting from the associated transient stress changes. Such a setting causes localized crustal thinning, rapidly followed by crustal shortening, and it provides an ideal intrinsic mechanism for obduction of ophiolites or a hyperextended continental margin, without a need for any far-field forcing or preexisting weaknesses in the upper plate.This work was supported by European Union FP7 Marie Curie ITN “Subitop,” grant agreement no. 674899. J. van Hunen acknowledges funding from the Natural Environment Research Council (NERC) (grant NE/M000281/1); V. Magni acknowledges support from the Research Council of Norway through its Centres of Excellence funding scheme, Project Number 223272. M.B. Allen acknowledges NERC grant NE/H021620/1. This work made use of the computational facilities of Hamilton HPC at Durham University.

中文翻译：

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弯曲的造山带、弧后盆地和作为不规则大陆边缘碰撞结果的俯冲

大陆碰撞通常涉及高度弯曲的被动板块边缘，导致海沟回滚期间的历时大陆俯冲。这样的系统可能具有弧后延伸和蛇绿岩在初始碰撞后发生的特征。现代例子包括 Alboran 和 Banda 弧。古代系统包括纽芬兰和挪威 Caledonides。虽然外力或先前存在的弱点经常被引用，但我们认为蛇绿岩内收同样可以由碰撞过程中的内部应力积累引起。在这里，我们在三维 (3-D) 热机械模型中模拟了与不规则俯冲大陆边缘的碰撞，并使用生成的应力场演化来了解由此产生的地质过程。结果显示了在碰撞历时开始期间张应力如何在上层板中局部化。这些应力会使覆盖板变薄，并可能打开弧后扩展中心。沿着整个海沟的碰撞迅速发生，伴随着这个扩张中心的倒置、蛇绿岩的外展和上覆板块的压缩。这些模型显示了不规则大陆边缘的俯冲如何形成高度弯曲的造山带。有了这种机制，在大陆碰撞期间，弧后大洋岩石圈的抑制自然会从给定的初始边缘几何形状演变而来。高度弯曲的造山带的形成仍然存在争议（Rosenbaum，2014）。提议的机制包括与沿变薄的褶皱冲断带变形相关的过程（Marshak，1988 年）、重力传播（例如 Edey 等人，2020 年）、或板块边界的沿走向迁移率变化（Rosenbaum 和 Lister，2004 年）。后者包括板块旋转、海沟回滚或大陆碰撞期间的压痕等过程（Rosenbaum，2014 年；Rosenbaum 和 Lister，2004 年）。 Alboran 和 Banda 弧是两个现代系统，与海沟回滚和沿走向的历时大陆俯冲有关（Spakman 和 Hall，2010 年；van Hinsbergen 等人，2014 年）。这两个地区都经历了相对于高度非线性被动边缘的海沟回滚（见图 1），其中大陆岩石圈沿海沟历时俯冲（Pownall 等人，2016 年；Spakman 和 Hall，2010 年；van Hinsbergen 等人，2014 年）。在班达地区，大陆物质最初 (15 Ma) 在塞拉姆俯冲 (Spakman and Hall, 2010)，与海沟旋转一致，紧随其后的是南部帝汶的大陆俯冲（4 Ma）（图1A）。大洋俯冲现已停止，沿整个大陆边缘发生碰撞。地中海西部 Alboran 盆地的构造历史存在争议（van Hinsbergen 等，2014）。大多数模型同意板块自 30-20 Ma 以来向西退缩进入变窄的 Alboran 海湾（图 1B）。这两个地区都具有令人费解的地质特征，例如上板块的伸展盆地（Pownall 等，2016；Watts 等） ., 1993)，以及挖掘出的地壳下大陆岩石圈（Frasca 等人，2017 年；Gueydan 等人，2019 年；Pownall 等人，2014 年）。Banda 系统涉及蛇绿岩内生（Ishikawa 等人，2007 年），但这在 Alboran 弧中尚未确定。世界上最大的次大陆地幔暴露，Alboran 弧中的 Ronda 和 Beni 橄榄岩（Gueydan 等人，2019 年）被认为是在板块断裂后因重力坍塌而挖掘出来的（Platt 和 Vissers，1989 年；Van der Wal 和 Vissers，1993 年），由较老侏罗纪裂谷边缘的逆冲作用（Tubia 等人，2009 年），或在大陆碰撞之前和期间上覆板块的过度伸展（Frasca 等人，2017 年；Gueydan 等人，2019 年；见图 1C） ）。在这些例子中，尚不清楚地质演化如何与俯冲大陆边缘的高度弧形几何形状和不规则形状相关联（如果有的话）。本研究的目的是检查不规则大陆俯冲过程中演化的板块应力和弯曲大陆边缘的形成。造山带，以更好地了解地质演化的驱动因素和控制因素。我们表明，不规则边缘碰撞初始阶段的局部张应力会导致短暂的弧后裂谷或扩张中心，一旦大陆俯冲沿海沟蔓延，这些中心就会迅速倒置。 我们研究了不规则边缘大陆碰撞期间的应力状态演变（图 2）在 3300 x 3960 x 660 km 大小的模型空间中。有限元代码 Citcom（Moresi 等人，1996 年；Zhong 等人，2000 年；Magni 等人，2014 年）求解动量、能量、质量和成分的守恒方程。我们使用了粘塑性流变学，包括扩散和位错蠕变、岩石圈屈服和上限粘度（Magni 等，2014；van Hunen 和 Allen，2011）。我们没有应用外部强迫；所有动力都是由内部浮力驱动的。俯冲板块和上覆板块被弱区隔开，并通过弱转换断层与相邻板块分离，以允许环形地幔流动（van Hunen 和 Allen，2011；Magni 等，2014）。当介入的大洋盆地关闭时，大陆岩石圈可以自由地向海沟移动并与上覆的板块发生碰撞。大陆地壳最初厚 40 公里；下伏地幔岩石圈从靠近海沟的 100 公里深度延伸到远场区域的 150 公里，以模拟较厚的板块内部（图 2B）。俯冲被动边缘包括（沿走向）宽度 wb 和宽度（这里用于横向宽度）bb 的海洋海湾，其侧翼与会聚方向成 α 角。为了研究这个海湾对不断变化的应力分布的影响，我们改变了初始宽度（在 600 到 1200 公里之间）和宽度（在 300 到 700 公里之间），同时保持侧面方向角 α 恒定。计算平行收敛应力场 σxx 以研究可能导致观察到的正常或逆冲断层的应力定位。图 3 描绘了俯冲大陆的模型演化，包括大洋湾 wb = 1000 km by bb = 600公里。最初，在所有模型中，大洋板块的负浮力驱动俯冲、海沟回滚和上覆板块的均匀伸展（图 3A）。海湾两侧的初始大陆俯冲局部降低了俯冲速度，海沟后退停止（图 3B）。然而，在被动边缘的大洋湾，海沟继续退缩。随着大陆碰撞的局部开始（图 2）。如图 3B) 所示，应力沿沟槽和上板开始显着变化。碰撞区域存在局部压缩，而靠近大洋湾的延伸继续施加板块拉力和海沟后退。不同的应力导致覆盖板的屈服和破裂。弧后扩展中心的开放（图 3C）使会聚速度短暂地增加了三倍（图 4A）。在弧后扩张开始后不久（~5 my），大洋湾完全俯冲，随后是大陆俯冲（图 3D-图 3F）。此时，年轻的大洋弧后盆地的脊垂直扩展距离仅为 166 公里（图 3D）。大陆地壳的高浮力降低了俯冲速度并阻止了海沟回滚（图 4A）。没有本地，沟槽的快速回滚驱动弧后区域的拉伸应力，弧后扩展停止，其应力状态在初始碰撞后的 10my 内从拉伸应力状态变为压缩应力状态（图 3E 和图 3F）。在这最后一个阶段，沿整个俯冲边缘的板块断裂结束俯冲并允许俯冲大陆开始剥脱。较小海湾的俯冲（图 4B）不会使上覆板块破裂产生弧后扩张，但它仍然使覆盖的大陆变薄；在碰撞开始时，地壳厚度从最初的 40 公里减少到 8 公里（图 4B；补充材料中的图 S1）。海湾宽度 bb 决定了上覆板块伸展阶段的持续时间，因此决定了大洋弧后盆地的存在与否。太窄的海湾（小 wb）不会产生足够的张应力，而最宽的海湾（wb = 1200 公里）缺乏所需的应力定位。当弧后扩张中心形成时，其扩张持续时间从最小盆地的 1 米到 5 米（参考模型，图 3），再到具有最大海湾的模型中的 10 米（wb = 1200 公里和bb = 600 km）并形成最大的弧后盆地（253 km 横向扩展距离）。不规则被动边缘的俯冲允许形成弯曲的造山带和上覆板块从拉伸状态到压缩状态的两阶段应力演化在碰撞过程中。我们的模型显示了在局部初始碰撞期间上覆板块的局部变薄或破裂是如何发生的，而大洋俯冲在其他地方继续进行。应力反转和压缩变形发生在第二阶段，即大陆完全俯冲期间。考虑到被动边缘的自然不规则形状，此类特征可能在碰撞带中很常见（Dewey 和 Burke，1974 年）。许多大陆碰撞数值模型都关注线性被动边缘（Schliffke 等，2019；van Hunen 和 Allen， 2011) 或倾斜碰撞 (Bottrill et al., 2014) 以研究俯冲大陆地壳的板片断裂和剥脱。大陆碰撞期间的压应力和由此产生的地形受板块耦合（Faccenda 等人，2009 年）、流变流动定律（Pusok 等人，2018 年）以及浮力比和收敛速度（Pusok 和 Kaus，2015 年）控制。还，在非线性流变学（Pusok 等，2018）的前提下，沿俯冲板块走向的横向成分变化可以触发弧后扩张中心的形成（Magni 等，2014；Menant 等，2016）。我们的模型结合了这些方法，并表明在弧后盆地中产生的从拉伸状态到压缩状态的应力反转类似于为蛇绿岩的外展（Cawood 和 Suhr，1992）或超伸展的大陆边缘（Gueydan 等人， 2019）。蛇绿岩形成的先前模型（例如，Duretz 等人，2016 年；Hässig 等人，2016 年）通常规定了“热异常”（Duretz 等人，2016 年）或热地幔上涌（Hässig 等人，2016 年）到大陆 - 海洋边缘以创建弱不连续性。远场强迫的缩短将导致大陆俯冲弱不连续性和蛇绿岩在大陆上的就位。我们的工作表明，这些外部因素不一定是必需的，因为碰撞在弧后区域产生了弱化和压缩应力，这是观察到的蛇绿岩外展和地壳剥脱所需的。我们模型中上下板块之间的界面是一个恒定粘度弱区：这决定了两个板之间的应力传递（Hassani 等人，1997 年；Faccenda 等人，2009 年）。在从俯冲到碰撞的转变过程中，这种耦合可能会发生变化（Luth 等，2010）。较低的流体和熔体渗透（Faccenda 等，2009）或低沉降速率会增加耦合（Burov 和 Toussaint，2007）并且可能比我们的模型更有效地将压缩应力传递到弧后区域。如果是这样，我们模型中弧后区域的压缩应力的时间和程度将被低估；即，在自然界中应该发生更快和更强的应力转移。相比之下，太高的板块耦合会结束缩短并导致区域弧前隆起（Luth 等，2010），而弧后区域不会缩短。 Banda 和 Alboran 系统中的观测证实了预测的应力和过程序列我们的模型（Gueydan 等人，2019 年；Spakman 和 Hall，2010 年；van Hinsbergen 等人，2014 年；见图 1C）。海沟回滚到班达弧导致横向弧-大陆碰撞和韦伯深盆地的同步张开（Pownall 等人，2016 年；Spakman 和 Hall，2010 年）。地壳下地幔岩石圈在最近的伸展盆地（Pownall et al., 2014）的角落被推挤，我们的模型预测地壳变薄以及从伸展到压缩的最快速变化。在 Alboran 弧中，沿整个弧地下存在一个高速体，被解释为 Ronda 和 Beni 橄榄岩的延续（Gueydan 等，2019）。回滚期间靠近海沟的局部张应力引起的裂谷过程（图 1C），然后是大陆俯冲期间的压缩和推力，已被建议触发超伸展的大陆边缘俯冲（Gueydan 等，2019）。在奥尔博兰弧，在板坯变窄期间，沟槽回滚率从快速后退（高达 8 厘米/年）降低（van Hinsbergen 等人，2014) 到俯冲停止与大陆地壳沿整个海沟的俯冲同时发生。我们的模型显示在大洋盆变窄期间俯冲停止和大陆完全碰撞（图 4A）符合这些趋势。 Caledonide 造山带大规模大陆碰撞期间的边缘（Cawood 和 Suhr，1992 年；Slagstad 和 Kirkland，2018 年）。在 Baltica-Laurentia 碰撞期间，纽芬兰（Cawood 和 Suhr，1992 年）和挪威（Slagstad 和 Kirkland，2018 年）的历时初始碰撞与伸展同时发生，如镁铁质层状侵入和蛇绿岩的形成所示，而俯冲的年代约为 15-20 年之后。在我们的模型中，随着沿整个海沟的大陆俯冲前弧后扩张开始约 5 米，并在我们的模型中弧后区域的压缩前约 20 米，我们估计在 5 至 20 米的回旋期间内发生俯冲。电弧形成，类似于观察。挪威 Caledonides 和 Newfoundland 的有限（海沟垂直）蛇绿岩尺寸（<100 公里）表明，新形成的扩张中心在碰撞开始时一定很小，并且扩张中心靠近主缝合线，其中后弧综上所述，具有不规则被动边缘的大陆碰撞不仅可以形成高度弧形的造山带，而且还可以由于相关的瞬态应力变化而导致上覆板块的复杂地质过程。这种环境导致局部地壳变薄，紧随其后的是地壳缩短，它为蛇绿岩或超伸展的大陆边缘提供了理想的内在机制，而无需任何远场强迫或上板块预先存在的弱点。这项工作得到欧盟 FP7 Marie Curie ITN “Subitop”的支持，授予协议编号。674899. J. van Hunen 承认自然环境研究委员会 (NERC) 的资助（授权 NE/M000281/1）；V. Magni 通过其卓越中心资助计划，项目编号 223272，感谢挪威研究委员会的支持。MB Allen 承认 NERC 赠款 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。并且它为蛇绿岩或超延展的大陆边缘提供了理想的内在机制，不需要任何远场强迫或上板块预先存在的弱点。这项工作得到了欧盟 FP7 Marie Curie ITN “Subitop”的支持，授予协议编号 674899. J. van Hunen 承认自然环境研究委员会 (NERC) 的资助（授权 NE/M000281/1）；V. Magni 通过其卓越中心资助计划，项目编号 223272，感谢挪威研究委员会的支持。MB Allen 承认 NERC 赠款 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。并且它为蛇绿岩或超延展的大陆边缘提供了理想的内在机制，不需要任何远场强迫或上板块预先存在的弱点。这项工作得到了欧盟 FP7 Marie Curie ITN “Subitop”的支持，授予协议编号 674899. J. van Hunen 承认自然环境研究委员会 (NERC) 的资助（授权 NE/M000281/1）；V. Magni 通过其卓越中心资助计划，项目编号 223272，感谢挪威研究委员会的支持。MB Allen 承认 NERC 赠款 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。这项工作得到了欧盟 FP7 Marie Curie ITN “Subitop”的支持，赠款协议编号。674899. J. van Hunen 承认自然环境研究委员会 (NERC) 的资助（授权 NE/M000281/1）；V. Magni 通过其卓越中心资助计划，项目编号 223272，感谢挪威研究委员会的支持。MB Allen 承认 NERC 赠款 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。这项工作得到了欧盟 FP7 Marie Curie ITN “Subitop”的支持，赠款协议编号。674899. J. van Hunen 承认自然环境研究委员会 (NERC) 的资助（授权 NE/M000281/1）；V. Magni 通过其卓越中心资助计划，项目编号 223272，感谢挪威研究委员会的支持。MB Allen 承认 NERC 赠款 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。艾伦承认 NERC 授予 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。艾伦承认 NERC 授予 NE/H021620/1。这项工作利用了达勒姆大学汉密尔顿高性能计算的计算设施。