Abstract. Continental collision is a crucial process in plate tectonics, whereas our understanding regarding the tectonic complexities at such convergent plate boundary remains largely unclear in terms of the evolution and the controlling parameters of its lateral heterogeneity. In this study, we conducted a series of two-dimensional numerical experiments to investigate how continental lithospheric thermal structure influences the development of lateral heterogeneity along the continental collision zone. Two end members were achieved: 1) Continuous subduction mode, which prevails when the model has a cold procontinental moho (Tmoho ≤ 450 °C). In this case, a narrow collision orogen develops, and the subducting angle steepens with the increasing retrocontinental Tmoho. 2) Continental subduction with a slab break-off, which generates a relative wide collision orogen, and dominates when the model has a relative hot procontinental Tmoho (≥ 500 °C), especially when the Tmoho ≥ 550 °C. In contrast, Hr is the second-order controlling parameter in varying the continental collision mode, while it prefers to enhance strain localization in the upper part of the continental lithosphere and promote the growth of shear zones there. By comparing the model results with geoscience observations, we suggest that the discrepant evolutionary paths from the continuous subduction underlying the Hindu Kush to the continental subduction after slab break-off beneath eastern Tibet may originate from the inherited lateral inhomogeneity of Indian lithospheric thermal structure. Besides, the high content of crustal radioactive elements may be one of the important factors that controls the formation of large thrust fault zones in the Himalayas.
Paleolatitudes of volcanic rocks reveal that prominent changes in volcanic trend of the Hawaii-Emperor hotspot chain represent meridional migration of the magma source. However, models assuming latitudinal plume migration fail to explain the observed age distribution, rock composition, and erratic paleolatitude changes of the oldest Emperor seamounts. Here we use data-assimilation models to better reproduce the Hawaii-Emperor hotspot track by systematically considering plate reconstruction, plume-lithosphere interaction, and simplified melt generation and migration. Our results show that plate drag and plume-ridge interaction are both important in explaining the observed seamount ages. These shallow dynamic processes could account for 50% of the observed paleolatitude's secular reduction and erratic variations over time, where the necessary southward migration of the Hawaiian plume root is significantly less than previously thought. We conclude that plume-lithosphere interaction represents a common mechanism in affecting hotspot track, and has important implications in understanding mantle dynamics and plate reference frames.
Abstract. Continental collision is a crucial process in plate tectonics. However, in terms of the evolution and the controlling parameters of its lateral heterogeneity, our understanding of the tectonic complexities at such a convergent plate boundary remains largely unclear. In this study, we conducted a series of two-dimensional numerical experiments to investigate how continental lithospheric thermal structure influences the development of lateral heterogeneity along the continental collision zone. The following two end-members were achieved. First, continuous subduction mode, which prevails when the model has a cold procontinental Moho temperature (≤450 ∘C). In this case, a narrow collision orogen develops, and the subducting angle steepens with the increasing retrocontinental Moho temperature. Second, continental subduction with a slab break-off, which generates a relative wide collision orogen and dominates when the model has a relatively hot procontinental Moho temperature (≥500 ∘C), especially when the Moho temperature ≥ 550 ∘C. Radioactive heat production is the second-order controlling parameter in varying the continental collision mode, while it prefers to enhance strain localization in the upper part of the continental lithosphere and promote the growth of shear zones there. By comparing the model results with geological observations, we suggest that the discrepant evolutionary paths from the continuous subduction underlying the Hindu Kush to the continental subduction after slab break-off beneath eastern Tibet may originate from the inherited lateral inhomogeneity of the Indian lithospheric thermal structure. Besides, the high content of crustal radioactive elements may be one of the most important factors that controls the formation of large thrust fault zones in the Himalayas.
Continental collision zones are widely distributed across the earth’s surface with diverse types of tectonic processes. Even the same collision zone shows significant lateral tectonic variations along its strike. In this study, we systematically investigated how plate velocity slowdown after the closure of the ocean influences the continental collision evolution, as well as the effects of kinematic characteristics and continental rheology on varying the continental collision modes in a plate velocity slowdown model. From the comparison between the constant plate velocity system (CVS) and the plate velocity-dropping system (VDS), we can conclude the following: Plate velocity dropping promotes the extension inside the slab by decreasing the movement of the surface plate, whereas slab pull increases as subduction continues. The timing of the subducting slab break-off and the polarity alteration was initiated earlier in the plate velocity drop models than in the constant plate velocity models, and fast convergence may have triggered multiple episodes of slab break-off and caused strong deformation adjacent to the collision zone. Parametric tests of the initial subducting angle, plate convergence velocity, and continental crustal rheological strength in VDS indicated the following: (1) Three end members of the continental lithospheric mantle deformation modes were identified from the VDS; (2) models with a low subducting angle, fast continental convergence velocity, and medium-strength overriding crust were more likely to evolve into a polarity reversed mode, whereas steep-subducting-angle, slow-plate-velocity, weak-overriding-crust models tended toward a two-sided mode; (3) a strong overriding continent is more liable to develop a stable mode; and (4) overriding crustal rheological strength plays a significant role in controlling changes in continental collision modes.
Abstract. Continental collision is a crucial process in plate tectonics, whereas our understanding regarding the tectonic complexities at such convergent plate boundary remains largely unclear in terms of the evolution and the controlling parameters of its lateral heterogeneity. In this study, we conducted a series of two-dimensional numerical experiments to investigate how continental lithospheric thermal structure influences the development of lateral heterogeneity along the continental collision zone. Two end members were achieved: 1) Continuous subduction mode, which prevails when the model has a cold procontinental moho (Tmoho ≤ 450 °C). In this case, a narrow collision orogen develops, and the subducting angle steepens with the increasing retrocontinental Tmoho. 2) Continental subduction with a slab break-off, which generates a relative wide collision orogen, and dominates when the model has a relative hot procontinental Tmoho (≥ 500 °C), especially when the Tmoho ≥ 550 °C. In contrast, Hr is the second-order controlling parameter in varying the continental collision mode, while it prefers to enhance strain localization in the upper part of the continental lithosphere and promote the growth of shear zones there. By comparing the model results with geoscience observations, we suggest that the discrepant evolutionary paths from the continuous subduction underlying the Hindu Kush to the continental subduction after slab break-off beneath eastern Tibet may originate from the inherited lateral inhomogeneity of Indian lithospheric thermal structure. Besides, the high content of crustal radioactive elements may be one of the important factors that controls the formation of large thrust fault zones in the Himalayas.
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