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The cause of magmatic tempo in an active plate margin remains controversial, partly due to lack of structural analysis. During 130–105 Ma, the magmatism in the South China Block (SCB) was significantly reduced (lull) and restricted around the Changle‐Nan'ao Belt (CNB) while the magmatism was highly active (flare‐up) in North China. For unveiling the tectonic role on magmatism, a multidisciplinary study including field and microscopic structural observations, magnetic fabric measurement (AMS), and zircon/monazite dating was conducted on the plutons with oriented minerals in the CNB. Structural analysis and AMS results show a highly clustered NE‐striking vertical foliation developed during the emplacement indicating a syn‐emplacement NW‐SE shortening regime. The geochronology results confirm that the emplacement occurred during 130–105 Ma. Regional geologic correlation indicates that the collision between the Dangerous Grounds‐West Philippines Block and SCB was responsible for this shortening regime. The collected depleted zircon εHf(t) data suggest that a possible collision‐triggered slab break‐off caused the syn‐collisional magmatic activity around the CNB. This study shows that the magmatic lull in the SCB was coeval with a crustal shortening regime due to the arrival of a microcontinent carried by the subduction slab, while the magmatic flare‐up was coeval with an extensional regime due to the subduction roll‐back and retreat as evidenced by the Cretaceous evolution of the SCB before and after the collision and that of North China which is unaffected by the collision. The cause of magmatic tempo in the continental margin is largely due to the tectonic evolution of underlain subduction slabs. Plain Language Summary: Magmatic activity is closely connected to human life as it provides us with useful metals, releases greenhouse gases, triggers natural hazards. It is necessary to explore what controls a magmatic activity. Several previous studies considered that a shortening regime with thickened crust causes strong magmatism (flare‐up). The South China Block (SCB) featured by alternating magmatic flare‐up and lulls, provides an appropriate research target to test this hypothesis. During the Cretaceous, the SCB was dominated by an extensional regime caused by the Paleo‐Pacific oceanic slab subduction. However, our structural analyses on the SCB document a shortening regime caused by the collision between the SCB and a microcontinent carried by the Paleo‐Pacific oceanic slab in the period of the Cretaceous. During the collision, the SCB was generally featured by a magmatic lull, although magmatic activity was only observed around the Changle‐Nan'ao Belt, probably caused by the break‐off of the subducted Paleo‐Pacific oceanic slab. Before and after the collision, the extensional regime caused by Paleo‐Pacific oceanic slab subduction was coeval with magmatic flare‐up. This study questions the previous claims and proposes that the tectonic evolution of the subducting slab may control the magmatic flare‐up and lull in the overlain active continental margin. Key Points: The 130–105 Ma syn‐tectonic plutons intruded the Changle‐Nan'ao Belt in a NW‐SE shortening regime caused by a microcontinent collisionThe shortening/extension regimes were coeval with magmatic lull/flare‐up in the East Asia Continental Margin during the CretaceousThe collision causing break‐off can account for the plutonism in the Changle‐Nan'ao Belt during the magmatic lull of the South China Block [ABSTRACT FROM AUTHOR]

The tectono-magmatic evolution of the North China Craton (NCC) plays a crucial role in understanding the Jurassic–Early Cretaceous (Yanshanian) intracontinental orogeny in East Asia. A holistic understanding of multi-phased deformation and magmatism in the NCC is greatly complicated by the sporadically distributed Mesozoic strata with significantly different stratigraphic associations in various zones. In this paper, we review the Jurassic–Early Cretaceous litho-stratigraphy with emphasis on unconformities to define a coherent chronostratigraphic framework of the entire NCC. Integrating available data concerning tectonic deformation, and geochemistry and fabric of igneous rocks into the well-established coherent chronostratigraphic framework, a four-stage tectonic evolutionary model of the NCC is proposed, providing new insights into the dynamics of the Yanshanian intracontinental orogeny in East Asia. The first stage concerns a N–S extension in the NCC during the Early–early Middle Jurassic (∼200–170 Ma), expressed by the E–W striking brittle normal faults developed in the Lower–lower Middle Jurassic strata, and magmatism along the southern and northern margins of the NCC. It could be related to the post-orogenic extension after the deep continental subduction of the South China Block beneath the NCC. The second one is characterized by a N–S compression (i.e., Event A of the Yanshanian orogeny) in the late Middle Jurassic (∼170–160 Ma), evidenced by the unconformity above the Lower–lower Middle Jurassic strata and the upper Middle Jurassic syn-tectonic deposition. The associated N–S directed thrusts and fault-related folds were mainly localized in the northern part of the NCC, possibly responding to the far-field compression related to the closure of the Mongol–Okhotsk Ocean. The third stage corresponds to a NW–SE compression (i.e., Event B of the Yanshanian orogeny) during the Late Jurassic–earliest Cretaceous (∼160–135 Ma), illustrated by the NW–SE directed thrusts and the overprint of pre-existing N–S directed thrusts by the latter NW–SE directed thrusts. It was well recorded by the Upper Jurassic–lowermost Cretaceous syn-tectonic deposition and the unconformity above. This NW–SE compression in response to the flat slab subduction of the Paleo-Pacific Plate had influenced the entire NCC. However, the latest Middle–early Late Jurassic (∼165–150 Ma) local NE–SW extension, recorded by ductile and brittle normal faults, magnetic lineation in granitic plutons, and magmatism that extended to Northeast China and its adjacent areas, also occurred in the northeastern part of the NCC. This could be related to tectonic transition from the N–S closure of the Mongol–Okhotsk Ocean to the NNW-directed subduction of the Paleo-Pacific Plate. In the latest stage during the Early Cretaceous (∼135–115 Ma), the large-scale crustal extension, characterized by metamorphic core complexes, magmatism, graben or half-graben basins, occurred in a vast area extending more than 4000 km, from Transbaikalia, through the NCC, to the South China Block. It could be the consequence of the lithospheric thinning and the formation of the wide rift due to the southeastward stress relaxation of the NW–SE convergent East Asian continent as the slab rollback of the Paleo-Pacific Plate. These results provide a notable example of polyphase intra-plate deformation and magmatism paradigm in response to intracontinental orogeny with variable plate-boundary geodynamics. [ABSTRACT FROM AUTHOR]

Abstract: Metamorphic Core Complexes (MCC) constitute remarkable features within wide rifts. Based on analogue and numerical modelling, MCC dynamics and structural development are mainly controlled by first geothermal gradient, second the compositional layering, and after the strain rate and partial melting. In the Late Mesozoic, continental extension occurred in East Asia leading to the development of MCC, magmatism and extensional sedimentary basins. Based on an integrated study (i.e. structural and finite strain analysis, petrofabrics, Anisotropy of Magnetic Susceptibility (AMS) and U/Pb on zircon dating), this paper aims at constraining the tectonic evolution and deformation mechanisms in the South Liaodong Peninsula (NE China). The Gudaoling massif is identified as a “migmatitic” MCC developed from Upper Jurassic (ca. 157–154Ma) to Early Cretaceous (ca. 128–113Ma). Intrusion of the Yinmawanshan synkinematic pluton (Early Cretaceous) to the south of the dome marks out the final stages of shearing along the Gudaoling detachment zone and of exhumation of the MCC into the upper crust. The Gudaoling MCC and the Yinmawanshan pluton stay in line with the coeval South Liaodong MCC, to the south, all making a ~140×30km wide extensional band formed during a regional E–W to NW–SE crustal stretching. The area shows a bi-phased development with a “slow” and a “fast” stage which corresponds to (1) crustal necking and (2) dome amplification/exhumation stages according to published thermo-mechanical modelling results. Finally, the Gudaoling MCC lower unit almost exclusively displays migmatites and anatectic granitoids of Late Jurassic and Early Cretaceous, respectively. Occurrence of partial melting during earlier stages of extension seems controlling the initiation of MCC (as a soft anomaly within the lower crust). In East Asia, a regional-scale thermal event, during Jurassic–Cretaceous times, may have significantly reduced the bulk lithosphere strength and locally induced partial melting, emphasizing pervasive deformations and development of a wide rift system. [Copyright &y& Elsevier]

Abstract: Mechanism and kinematics of the Late Mesozoic continental extension event of Eastern Asia are still debated. In order to better constrain its evolution, two granodioritic plutons of the Jiaodong Peninsula have been chosen as targets for a time-constrained palaeomagnetic study. Indeed, plutons are devoid of visible deformation, did not experience rotation along horizontal axis and are precisely dated by U/Pb and 40Ar/39Ar methods. Multidomain (MD) magnetite has been identified as the principal magnetic remanent carrier. The interpolation of existing and new U/Pb and 40Ar/39Ar ages revealed that characteristic remanent magnetisation was acquired in a narrow range of 116±2Ma. Twenty out of 27 sites present stable magnetic directions calculated from high-temperature or high-coercive components. The observations of the solo normal magnetic polarity for this palaeomagnetic collection and of the magnetic remanent age consistent with the Cretaceous Normal Superchron (CNS) argue that the characteristic magnetic remanence may be considered as primary. Detailed field observations of the intrusive relationship between the plutons and country rocks and Anisotropy of Magnetic Susceptibility (AMS) study reveal the absence of the subsequent deformation of plutons, or rigid rotation of plutons along a horizontal axis. Two palaeomagnetic poles have been therefore calculated from these plutons. Among 12 out 15 Cretaceous palaeomagnetic poles, including the two new poles provided by this study, from the Jiaodong Peninsula and on both sides of Tan-Lu and Muping-Jimo faults are statistically consistent. As a result, the Jiaodong Peninsula behaved as a rigid block as internal deformation appears negligible. The remaining three derived poles are probably due to the secular variation or/and the vicinity of fault zones near of the palaeomagnetic sampling site. Thus, they can not be applied to the peninsula-scaled tectonics. Comparison of these time-constrained Cretaceous palaeomagnetic results of the Jiaodong Peninsula with those of North China Block (NCB) indicate that the Jiaodong Peninsula was rigidly attached to NCB since, at least, the Cretaceous as residual difference is clearly insignificant with respect to the error brackets. These new palaeomagnetic results confirm that the relative clockwise (CW) rotation of Eastern Liaoning-Korea Block (ELKB) with respect to NCB does not affect the Jiaodong Peninsula as a rigid block, nevertheless, some tectonic structures have been reactivated since Cenozoic and local rotations could be produced. This palaeomagnetic study reveals that the Late Mesozoic extension in Eastern Asia is heterogeneously expressed in time and space. The complete understanding of the mechanism(s) of this extensional event needs further multidisciplinary investigations. [Copyright &y& Elsevier]