The Liaonan/Wanfu metamorphic core complexes in the Liaodong Peninsula: Two stages of exhumation and constraints on the destruction of the North China Craton

Abstract

[1] The Liaodong Peninsula Early Cretaceous extension province (LEP), located in the eastern part of the North China Craton (NCC), was highly extended in early Cretaceous. The Liaonan and the Wanfu metamorphic core complexes (MCCs) are two most important elements in the province. Both are typical Cordilleran-type core complexes that are composed of a general three-layered structure but show various differences. Shearing along the Jinzhou detachment fault zone in the Liaonan MCC generated ductile to brittle tectonites, various deformation microstructures, and several types of quartz c-axis fabrics, implying that the MCC has a complicated progressive exhumation history. However, medium-temperature microstructures and fabrics are superimposed by low-temperature features along the Wanfu detachment fault zone suggesting a relatively short and simple exhumation history of the Wanfu MCC. Magmatic zircon U-Pb geochronological dating reveals that the early Cretaceous extension of the LEP began with the initiation of shearing along the Jinzhou detachment fault zone and exhumation of the Liaonan MCC before ca. 134 Ma. Subsequently, relatively slow cooling and exhumation of the lower plate accompanied a giant magmatic event from 130 Ma to 120 Ma. Exhumation of a new MCC, i.e., the Wanfu MCC, was triggered by progressive extension after ca. 120 Ma. Rapid cooling and exhumation of the metamorphic lower plate of the two MCCs are attributed to coeval detachment faulting along both the Jinzhou and Wanfu faults from 120 Ma to 113 Ma. The extension ended at ca. 107 Ma. These data provide reliable evidence that the two MCCs were exhumed progressively and sequentially during two stages of crustal extension of the LEP. Our results indicates that heterogeneous lithosphere extension and upper-middle crust/upper mantle detachment, possibly due to the interaction between the Paleo-Pacific and Eurasian plates, are among the most important processes during the early Cretaceous thinning of the lithosphere. Tectonic extension may have led to the detachment in East Asia, which contributed to the thinning of the lithosphere and the destruction of the NCC. A phase of uniform and consistent WNW-ESE extension was responsible for the generation of the extensional structures in the eastern Asia continent and the destruction of the NCC.

Coexisting Early Cretaceous High-Mg Andesites and Adakitic Rocks in the North China Craton: the Role of Water in Intraplate Magmatism and Cratonic Destruction

“…Wu et al, 2005a, and this study) and crustal extension (e.g. Liu et al, 2013). As a result, destruction of the cratonic root probably attained its climax at that time.…”

“…The early Cretaceous igneous rocks developed coevally with late Mesozoic metamorphic core complexes (MCC) and occur as plutonic intrusions in the lower plates of the complexes and as volcanic rocks in the supradetachment basins of the MCC ( Fig. 1b; Liu et al, 2013). The MCC were the consequence of crustal or lithospheric extension, which was probably induced by collapse of crust over-thickened as a result of earlier orogenic processes (Wang et al, 2012) or by retreat of the subducting Paleo-Pacific plate beneath the East Asia plate .…”

“…Moreover, these adakitic lavas were developed in association with late Mesozoic metamorphic core complexes and erupted in fault-bounded extensional basins ( Fig. 1b; Liu et al, 2013). Detailed studies on the coexistence of Cretaceous volcanic-sedimentary basins, low-angle normal faults, exhumed high-grade metamorphic rocks with early Cretaceous cooling ages, and widespread A-type granitoids in the lower plate of the MCC demonstrate that the crust of the Liaodong Peninsula was relatively thin and experienced exceptionally intense extension during early Cretaceous times (Liu et al, 2005.…”

Coupling and transition of Meso–Cenozoic intracontinental deformation between the Taihang and Qinling Mountains

“…The initial time of extension in the Hefei Basin is the middle Early Cretaceous, continuing to the end of the Paleogene. Some scholars (Zhu et al, 2012a;Wang et al, 2012;Liu et al, 2013) stressed that the extensional activities occurred during the lithospheric thinning of the North China Craton related to high-angle subduction of the Pacific Plate, but the extension is different from stretching in the back-arc basin in the extensional direction, being perpendicular to the paleoPacific Subduction Zone.…”

Evolving magma sources during continental lithospheric extension: Insights from the Liaonan metamorphic core complex, eastern North China craton

“…In such cases, tectonic lithosphere extension may dominate over magmatism. The two processes are mutually enhancing and are suggested to be the parallel-products of continental lithospheric extension (e.g., Konstantinou et al, 2013;Liu et al, 2013). The relation (if any) between magmatic activity and detachment faulting thus remains a persistent question (Fornash et al, 2013).…”