Mesozoic tectono-magmatic evolution of the Tanlu Fault zone and its relationship with the destruction of the North China Craton
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ABSTRACTThe lithosphere beneath the eastern part of the North China Craton (NCC) is widely recognized as having undergone extensive thinning and destruction since the Mesozoic. Although most models propose that the destruction was related to the Paleo-Pacific subduction, the timing and mechanism of the destruction remains controversial. The Tanlu Fault is the largest deep strike-slip fault zone in eastern China. It is an ideal object to study the destruction of the NCC and the subduction history of the Paleo-Pacific. In this review, we compile the ages and geochemical data of the Mesozoic magmatic rocks along the Tanlu Fault zone, in combination with evidence related to the tectonic evolution of the Tanlu Fault during this time. We further discuss the relationship between subduction of the Paleo-Pacific and the thinning and destruction processes affecting the NCC lithosphere. In the Late Triassic period, adakitic rocks, A-type granites, and mafic rocks generated from depleted asthenosphere were distributed in Liaoning and Shandong provinces along the Tanlu Fault. These magmas were related to an extensional environment caused by exhumation of the Yangtze block after subduction. The magmatic characteristics indicate that the lithospheric mantle began to change from cold and refractory to a hot and active, suggesting that the NCC began to undergo cratonic destruction at this time. The magmatic lull ranging from 200–185 Ma represents the transition for the Tanlu Fault zone tectonic domain from Paleo-Asian Ocean subduction in the north to the Paleo-Pacific subduction in the east. During the Jurassic, the NCC was also affected by subduction and compression of the Mongol – Okhotsk domain in the north and the influence of the Tethys tectonic domain in the south. Under this multi-directional compression, the crust thickened and the subducted slabs were dehydrated and melted, triggering partial melting of the overlying lithospheric mantle, providing a heat source for partial melting of the crust. At the end of the Jurassic, due to the steepening of the subduction angle of the Paleo-Pacific plate and the roll-back of the plate at that time, another magmatic lull (155–145 Ma) occurred in the Tanlu Fault area. In the early Early Cretaceous, due to a change of the Paleo-Pacific subduction direction (from NW to NNW), a large-scale strike-slip movement took place along the Tanlu Fault zone, and the study area began to experience extensive magmatism. At ca. 125 Ma, A-type granites were formed, representing the large-scale extension. At ca. 122 Ma, OIB-like mafic rocks began to intrude, which indicate that the geochemical properties of the lithospheric mantle of the NCC underwent a fundamental transformation at this time. Hence, the lithospheric mantle of the NCC was replaced by new lithospheric mantle. Slab subduction certainly weakened the NCC. However, the studies of mantle peridotite xenoliths in Cenozoic basalts indicate that the large fault zone (Tanlu Fault) was the priority area for lithospheric mantle transformation and replacement. Taking the time and space distribution characteristics of the NCC destruction into consideration, thermochemical erosion was an indispensable destruction model. According to magmatic and structural evidence, the destruction of the NCC was indeed related to the Paleo-Pacific movement. Besides, it should be noted that the Tanlu Fault was also a factor that cannot be ignored.KEYWORDS: North China CratonTanlu FaultPaleo-Pacific platelithospheric thinningMesozoic AcknowledgmentsThe first author would like to thank Professor Simon Wilde for his patient revision to improve the early draft. We really appreciate Professor Stern for his suggestions and patience. We are very grateful to the two reviewers (Professor Wen-Liang Xu and Professor Ross N. Mitchell) for their comments and suggestions, which have greatly improved the manuscript. We thank members of the Beijing SHRIMP Center for their help with SHRIMP analysis and zircon CL imaging.Disclosure statementNo potential conflict of interest was reported by the author(s).Supplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2023.2269221Additional informationFundingThis study was financially supported by Key Laboratory of Gold Mineralization Processes and Resource Utilization, MNR, Shandong Provincial Key Laboratory of Metallogenic Geological Process and Resource Utilization (KFKT202101), and China National Space Administration (Grant no. D020205).Cite
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The north China craton (NCC) is one of the oldest cratons in the world; however, the lithosphere of the craton was destructed during Phanerozoic tectonism and then became tectonically and seismically active. Because the lithospheric structure of this complex craton has not been well studied, the mechanism behind the thinning, transformation, and destruction of the lithosphere remains debated. Using an efficient and scalable 3‐D surface wave tomography method, we obtain a high‐resolution regional S wave velocity model that shows the three‐dimensional lithospheric structure of the NCC. In addition, we convert the S wave structure to an estimated thermal structure using accepted relationships between S wave velocity and temperature. The model images a large upper mantle low‐velocity body beneath the eastern NCC, especially beneath the seismically active zone from Tangshan to Xingtai. This body is interpreted to represent hot material or volatiles escaping from the slab edge in the transition zone between the upper and lower mantle. The low‐velocity body is a key piece of evidence in demonstrating thermochemical bottom‐up erosion/transformation of the overlying cratonic lithosphere, thereby leading to destruction of the lithosphere, which may have occurred during the Cenozoic. This erosion mechanism appears to have had less influence in the western NCC (Ordos block); however, our results reveal a ∼130‐km‐thick lithosphere beneath the present cratonic Ordos block, which is thinner than the ∼200 km thickness of the NCC lithosphere during the Paleozoic, as determined from analyses of xenoliths.
Seismic Tomography
Low-velocity zone
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Abstract The nuclei of continents, manifested as cratons, are the most long-lived parts of Earth’s lithosphere. However, ancient cratons in some areas can be substantially destroyed through mechanisms that are not fully understood. We used experimentally calibrated geobarometers to calculate the equilibrium pressures of mafic magmas in the North China craton, which directly constrain the evolving depth of the lithosphere-asthenosphere boundary beneath the craton through time. We show that the lithospheric thickness of the eastern part of the craton decreased from ~200 km to ~35 km in the Early Cretaceous. This intense destruction took place within a short time interval of ~10 m.y., at least locally. Following this destruction, the lithosphere gradually rethickened and stabilized as the upwelling asthenosphere cooled and formed a juvenile lithosphere. We suggest that this catastrophic lithosphere thinning resulted from wholesale lithosphere delamination. As a consequence of this catastrophic loss of thick mantle roots, the eastern part of the North China craton may have undergone rapid crustal rebound and surface uplift, as recorded by the regional unconformities formed between 130 and 120 Ma in the destructed area.
Asthenosphere
Delamination
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Asthenosphere
Receiver function
Lithospheric flexure
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几何学并且北方中国 craton (NCC ) 的合并预定是争论的与有地区性的结构的显著地不同的解释的三个主要模型一起，地球年代学，和地质的关系。赵 G C 等的模型。建议 NCC 的东方、西方的块独立形成了在太古代，并且活跃边缘在在 2.5 和 1.85 Ga 之间的东方块上被开发，二什么时候堵住，在蘸 subduction 的东方上面碰撞了地区。Kusky 等的模型。想从在大约 2.7 Ga 的一个未知更大的大陆的东方块 rifted ，并且与一条弧经历了碰撞(也许属于西方的块)在在 2.5 Ga 的一个蘸西方的 subduction 地区上面，并且当 NCC 加入了哥伦比亚 supercontinent 时， 1.85 Ga 变态与沿着 craton 的北边缘的碰撞有关。福莱等的模型。在中央 orogenic 带建议二碰撞，在 2.1 和 1.88 Ga。最近的地震结果两个都支持 Kusky 等的模型。并且福莱等，在中央 orogenic 带(圆块) 下面显示出那 subduction 是指导西方的，并且有一秒，定位到蘸在西方的块(Ordos craton ) 下面的圆块的东方的蘸西方的 paleosubduction 地区。通过地球物理识别的边界不与在赵等建议的 Trans 北方中国 orogen 的边界相关。模型，和 subduction 极性在由那个模型预言了那对面。地震侧面与在在 Kusky 等的模型预言的 COB 下面的一个蘸西方的 subduction 地区上面的太古代的碰撞一致，并且第二个蘸西方的 subduction 地区与二个事件在福莱等建议了一致。当模特儿。
Supercontinent
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Abstract Recently, the continually increasing availability of seismic data has allowed high‐resolution imaging of lithospheric structure beneath the African cratons. In this study, S‐wave seismic tomography is combined with high resolution satellite gravity data in an integrated approach to investigate the structure of the cratonic lithosphere of Africa. A new model for the Moho depth and data on the crustal density structure is employed along with global dynamic models to calculate residual topography and mantle gravity residuals. Corrections for thermal effects of an initially juvenile mantle are estimated based on S‐wave tomography and mineral physics. Joint inversion of the residuals yields necessary compositional adjustments that allow to recalculate the thermal effects. After several iterations, we obtain a consistent model of upper mantle temperature, thermal and compositional density variations, and Mg# as a measure of depletion, as well as an improved crustal density model. Our results show that thick and cold depleted lithosphere underlies West African, northern to central eastern Congo, and Zimbabwe Cratons. However, for most of these regions, the areal extent of their depleted lithosphere differs from the respective exposed Archean shields. Meanwhile, the lithosphere of Uganda, Tanzania, most of eastern and southern Congo, and the Kaapvaal Craton is thinner, warmer, and shows little or no depletion. Furthermore, the results allow to infer that the lithosphere of the exposed Archean shields of Congo and West African cratons was depleted before the single blocks were merged into their respective cratons.
Seismic Tomography
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Abstract We propose that subducting slabs may cause lithospheric removal by directing mantle flow along the craton margin. This process could carve and shape the cratons, leading to conditions that impact the overall (in)stability of the lithosphere. We use three-dimensional geodynamic models to investigate how subduction-driven directed flow interacts with cratonic lithosphere of differing shape, concluding that the margin shape controls both channelization of flow around the craton as well as the potential for destruction. While the simulations show that all craton shapes aid in channelization, the cratons with straight vertical margins are the most resistant to deformation, and the cratons with gradually thickening margins are less resistant to deformation. The dependence on shape could contribute to the progressive removal of cratonic lithosphere along its margin in a runaway process until a more stable vertical margin shape evolves.
Margin (machine learning)
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