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As a part of the Columbia supercontinent, the North China craton is an ideal object for studying the evolution of supercontinent assembly and the mechanism of orogenesis in the Paleoproterozoic. The Jiao-Liao-Ji belt, located in the eastern part of the North China craton, provides important clues for our understanding of Paleoproterozoic orogenic processes. A series of Paleoproterozoic granitic gneiss domes is preserved in the Liaodong segment of the Jiao-Liao-Ji belt. These domes are cored by the Liaoji granitic gneisses (emplaced at 2250-2150 Ma) and mantled by metamorphosed volcanic-sedimentary rocks (deposited at 2200-1940 Ma). Combining multiple lines of evidence from mesostructures and microstructures, kinematics, magnetic fabrics, and crystallographic fabrics, we suggest that the granitic gneiss domes reflect inhomogeneous shearing of the middle to lower crust during Paleoproterozoic orogenic processes. Intensive layer-paralleling shearing characterized subhorizontal flow during nearly E-W--oriented compression. As a hot orogen formed in the Paleoproterozoic, the orogenic deformation in the Jiao-Liao-Ji belt was characterized by extensive doming due to dominant subhorizontal flow and subsidiary vertical flow in the middle to lower crust. [ABSTRACT FROM AUTHOR]

The debate on the role of vertical versus horizontal tectonism in Archean cratons is intimately linked to the initiation of plate tectonics. The dome-and-keel architecture has been considered as a consequence of vertical tectonism. Although such a structural pattern is documented in some Mesoarchean and older cratons, such as the Kaapvaal and Pilbara cratons, whether it also occurs in Neoarchean cratons is poorly constrained. Determining the kinematics, structural evolution, and the timing of these structures is crucial in understanding how the tectonic behavior operated during the evolution of the early Earth. The North China Craton, especially its eastern part, is a Neoarchean continental block and preserves typical greenstone- granite rock assemblages. Detailed structural mapping reveals that the Anziling area (east China) is characterized by a typical dome structure without significant reworking by later deformation. The dome is in tectonic contact with a supracrustal rock assemblage that is now the dip-slip Shuangshanzi ductile shear zone. In the supracrustal rocks, compositional layers are folded into upright isoclinal folds. Meanwhile, along the shear zone, foliation varies from NNW to SW with sub-vertical dip. Mineral stretching lineations indicate a sinistral shear sense with a slightly oblique-slip component in the north, but show NWW-directed and SW-directed steep dip-slip shear in the west and south, respectively. Kinematic indicators imply that the granitic dome formed through a vertically upward movement accompanied by an uneven clockwise rotation. The supracrustal rocks sank downwards to form the regional keel structure. Structural data suggests that the Anziling area is a typical dome-and-keel structure. U-Pb zircon dating on pre-, syn-, and post-tectonic dykes indicate that the dome-and-keel structure formed at 2530-2500 Ma, and was intimately related to the emplacement of tonalite-trondhjemite-granodiorite granitoids. New data from this study suggest that until the late Neoarchean, the vertical tectonism was still a dominant tectonic regime that was operating in the eastern North China Craton. [ABSTRACT FROM AUTHOR]

The relationship between the North and South China blocks, particularly their spatial- temporal framework and evolutionary history, has been widely debated. We conducted a comprehensive study of the structural geometry and kinematics of the thrust belts in the intersection zone between the Dabashan and eastern Sichuan Basin based on seismic data, drilling data, field investigation data, and zircon and apatite (U-Th)/He thermochronology data. These data sets provide important insights into the relationship between the North and South China blocks during the post-orogenic process. Due to the detachments, the strata of the eastern Sichuan Basin can be divided into four structural intervals characterized by duplex structures and fault-related fold structures. Balanced restoration indicates the vertical differences are represented by the shortening ratio of the upper structural interval of ~6%, that of the middle ~10%, and that of the lower ~7%. Besides, the shortening ratios indicate an increasing tendency of the deformation intensity from the west to the east. The (U-Th)/ He dating results suggest two age ranges, i.e., from 180 Ma to 130 Ma and from 50 Ma to 20 Ma, respectively. These age data sets also imply a younger tendency westward. The intersection zone may have experienced the following stages since the late Mesozoic era: (1) the stable continental sedimentation stage from the Late Triassic to the Late Jurassic epochs; (2) the continuous thrust stage from the Late Jurassic to the early Paleogene epochs, which is associated with the subduction of the Paleo-Pacific Ocean; and (3) the uplift and denudation stage as a whole caused by the uplift of the Tibetan Plateau since the Paleogene period. [ABSTRACT FROM AUTHOR]

The ca. 2.54-2.51 Ga Dengfeng greenstone belt in the southern section of the Central orogenic belt of the North China craton consists of structurally juxtaposed slices of meta-ultramafic, metamafic, and felsic igneous rocks, metasedimentary rocks, including minor banded iron formation. The complex was metamorphosed to greenschist to amphibolite facies at ca. 2.5 Ga and intruded by ca. 2.50-2.42 Ga mafic and felsic plutons/dikes. Detailed field mapping and structural analyses show that the different lithostructural units, including a metamafic-dominant unit and a metasedimentary-dominant unit, are in tectonic contact, with complex thrust imbrication and multiple brittle and ductile deformation. The metasedimentary-dominant unit consists of coherent schist-metabasalt sequences, metaturbidites, and chaotic mélanges that are characterized by typical duplex structures and block-in-matrix fabrics, closely resembling the lithostratigraphy and structural patterns of Phanerozoic accretionary complexes. Together with distinctive and diagnostic geochemical signatures of metabasalts, sanukitoid-like metadiorite, and syntectonic adakitic sills/dikes, we interpret the Dengfeng greenstone belt as Neoarchean forearc and accretionary complexes consisting of dismembered forearc crustal sheets in the west and accreted oceanic plate stratigraphy in the east that were structurally imbricated at a convergent plate margin. The kinematic indicators and the spatial configurations of different tectonic units suggest a near-southwest-dipping intra-oceanic subduction zone beneath the arc in the Central orogenic belt, which later evolved into an arc-continent collision with the Eastern block. The accreted arc and accretionary prism are unconformably overlain by a clastic sedimentary wedge, the lower part of which has a maximum depositional age of ca. 2.45 Ga and is interpreted as a foreland basin sequence related to this collision. Documentation of the Neoarchean Dengfeng forearc and accretionary complexes demonstrates that ca. 2.5 Ga intra-oceanic subduction, oceanic plate stratigraphy accretion, and arc-continent collisional events occurred in the southern section of the Central orogenic belt of the North China craton. The accretion of the 2.54-2.51 Ga arc to the continental margin of the Eastern block marks an early episode of mountain building in the Central orogenic belt, which played an important role in the lateral growth of the North China craton. [ABSTRACT FROM AUTHOR]