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The Northern Liaoning Complex in northeastern China constitutes an important component of the Eastern Block in the North China Craton. The major lithologies consist of Archean granitoid gneisses with minor supracrustal rocks occurring as tectonic lenses. This study presents zircon Lu–Hf isotopic data for the first time as well as new SHRIMP zircon U–Pb data of the major lithologies from the Northern Liaoning Complex, in order to elucidate the crustal evolution of the complex and provide new constraints on the Neoarchean crustal evolution of the Eastern Block in the North China Craton. Magmatic zircon U–Pb data from this study show that the protolith magmas of the supracrustal rocks and granitoid gneisses were generated during ∼2.55–2.50 Ga. Metamorphic zircons document consistent metamorphic ages at 2.49–2.48 Ga, suggesting a regional metamorphic event immediately after the magmatism at the end of the Neoarchean in the Northern Liaoning Complex. Inherited/detrital zircons of 2.79–2.60 Ga suggest possible existence of ancient crust in this region. Zircon Lu–Hf isotopic compositions show that the magmatic zircons have variable ɛ Hf ( t ) values from −4.0 to +9.0 with depleted mantle model ages of 3.6–2.5 Ga, of which most ɛ Hf ( t ) values are positive with a model age peak at 2.9–2.7 Ga. These zircon Hf signatures reveal major juvenile crustal growth with additions of older crustal materials during 2.9–2.7 Ga, and a crustal reworking event with minor juvenile additions at 2.6–2.5 Ga in the studied area. Integrated with previous data from other Neoarchean complexes in the Eastern Block, both the major juvenile crustal growth during 2.9–2.7 Ga and the strong crustal reworking at 2.6–2.5 Ga contribute to the extensive Neoarchean crust formation of the Eastern Block in the North China Craton. The North China Craton share similar Neoarchean continental crustal evolution to other cratons in the world, though it is distinctively featured by intensive tectonothermal overprinting at the end of the Neoarchean. [ABSTRACT FROM AUTHOR]

The volcanic rocks in the eastern part of Jiangnan orogen provide an important suite to investigate magma petrogenesis and tectonic evolution of South China Block. We carried out a combined study of geochronology and geochemistry for the bimodal association of basalts and rhyolitic tuffs from the Shuangqiaoshan Group in south Anhui Province. Zircons from a basalt and two rhyolitic tuff samples yield crystallization ages of 829 ± 12 Ma, 832 ± 9 Ma and 832 ± 10 Ma, respectively. The basalts are characterized by left-sloping REE distribution patterns, enriched large iron lithosphere elements (LILEs, e.g. Rb, Ba, K) and depleted high field strength elements (HFSEs, e.g. Nb, Ta) relative to those in N-MORB, resembling those of modern Central Lau back-arc basin basalts (BABB). In addition, they have positive ɛ Nd ( t ) values (+4.6 to +5.7) with initial 87 Sr/ 86 Sr ratios in the range of 0.70706–0.70719. These geochemical and isotopic signatures indicate that the basalts were derived from an N-MORB-like source modified by slab-derived fluids. The rhyolitic tuffs have high SiO 2 (72.9–78.3 wt %) contents and high 10,000*Ga/Al ratios (mostly >2.6). Taking into account their aluminous nature (A/CNK > 1.1), they are affinitive to aluminous A-type granites. They invariably show a relative enrichment in light-REE, and strong negative Eu anomalies (Eu/Eu* = 0.16–0.31) and negative anomalies in HFSE, Sr and P compared with the neighboring elements in their trace element spidergrams. Their ɛ Nd ( t ) values range from −2.1 to +0.1. Detailed elemental and isotopic data suggest that the rhyolitic tuffs formed by partial melting of mafic lower crust triggered by asthenosphere upwelling. The occurrence of bimodal volcanic rocks with the basalts showing geochemical affinity to intra-oceanic BABB appears to support the development of a Neoproterozoic back-arc basin in the eastern part of Jiangnan orogen at ca. 830 Ma. Combined with the published data from central and western part of Jiangnan orogen, it is inferred that the back-arc basin developed in the entire Jiangnan orogen during 850–810 Ma. Considering the age of the strata overlying the folded basement sequence, we suggest that the final collision of the Yangtze and Cathaysia blocks happened during 820–810 Ma along the Jiangnan orogen. [ABSTRACT FROM AUTHOR]

The Hongliuhe ophiolite is a fragment of the early Paleozoic oceanic crust situated in a suture zone central to the Beishan orogenic collage, which is a subset to the Central Asian Orogenic Belt in Northwest China. It has lithologic, geochemical and chronological similarities to the Yueyashan–Xichangjing ophiolite 400 km east, along strike, allowing for correlative interpretations of marginal seafloor spreading processes. The Hongliuhe ophiolite is explored in this study with complete petrologic, geochemical and structural descriptions. The ultramafic body comprises cumulate-layered lherzolite and gabbro plutonic lithologies, tectonized with syn-magmatic extension. A U–Pb age of 520.3 ± 5.8 Ma was obtained by SHRIMP analysis of zircons from a pegmatitic gabbro. The ultramafic rocks are variably depleted and some show refertilization of LILE’s consistent with slab dehydration in a supra-subduction mantle wedge. Mineral chemistry shows high Cr# (36–82) populations of spinel, and wide-ranging lower Mg# (8–50), consistent with known forearc peridotite chemistry partially re-equilibrated by tectonism or through staged magmatism. Olivine and pyroxene chemistries are consistent with this interpretation. A thin volcanic cover is interlayered with red cherts, and has a bimodal set of geochemical signatures, both island-arc tholeiite and calc-alkaline. They bear distinct Nb–Ta anomalies consistent with slab-derived fluid initiated melting in a supra-subduction environment. Coarse volcaniclastic turbidites infilled paleo-topography along the ophiolite, and they are interbedded with quartzofeldspathic sandstones, indicating an initial proximity to an arc. The sandstones contain detrital spinel with analyses showing relation to both the ophiolite and possibly a secondary alkalic volcanic source. The supracrustal sequence continues with a thick, contiguous covering of margin-related rocks, including interlayered limestone, pyroclastic and siliciclastic rocks, and basalts. As a constraint on emplacement we provide an U–Pb Zircon SHRIMP date (413.6 ± 3.5 Ma) from an undeformed granitoid body intruded within the overlying stratigraphy. The entire analysis paints a picture of subduction rollback-related extension affecting the margin of an emerging or mature arc just prior to a known magmatic cycle that ended with a collision in the Devonian at the latest. This suture is one of many in the Beishan, and our interpretation provides evidence in a long running debate supporting accretionary orogenesis in an island-arc archipelago as the main system for growing sialic crust in the Paleozoic central Asia. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents petrography, zircon U–Pb ages and Hf isotopic data as well as whole-rock Sm–Nd isotopic data for mafic granulites, metapelitic rocks and high-grade marble from the Kongling Complex in the Yangtze Block, South China. Petrographic observations indicate that these three types of rocks experienced high-pressure metamorphism. Their mineral assemblages and P–T conditions define a clockwise P–T path involving isothermal decompression following the peak high-pressure metamorphism, which is considered to record a continent–continent collisional event. This is systematic documentation of the tectonic evolution of the Kongling Complex from 2.1-2.0Ga deposition (constrained by youngest detrital zircon and metamorphic zircon) through ~2.0Ga collision (high-pressure metamorphism) and syn-collisional partial melting (S-type granite and migmatization of TTG gneiss) to ~1.85Ga post-collisional extension (A-type high-K granite and mafic dyke). These ages are broadly coincident with global collisional events (2.1–1.8Ga) that led to the assembly of the Palaeo-Mesoproterozoic Columbia (or Nuna) supercontinent. Therefore, this study provides strong evidence that the Yangtze Block in South China was a component of the Columbia supercontinent. [Copyright &y& Elsevier]

Abstract: The Superior Boundary Zone separates the Neoarchean Superior Province to the southeast from the Paleoproterozoic Reindeer Zone of the Trans-Hudson Orogen to the northwest. In northern Manitoba, late convergence along the zone in the Paleoproterozoic has previously been interpreted in terms of a promontory model, where the Superior Province indents the Reindeer Zone towards the northwest. We present a modified promontory model that includes a WNW transport direction of the Superior Province and lateral escape of a segment of the Superior Province (the Split Lake Block) along the northern margin of the promontory. The model is based on the kinematics of an array of shear zones along the Superior Boundary Zone that are interpreted as having been active concurrently. Tectonic escape of the Split Lake Block occurred in a manner similar to the extrusion and rotation of the Indochina block along the eastern margin of the Himalayas, but at a much smaller scale. Our model explains shear zone kinematics, but also the curvilinear nature of some of the shear zones and a high component of along-strike stretch along one of the shear zones. [Copyright &y& Elsevier]

Reports an example of promontory-promontory collision from the Canadian Appalachians. Proposed model that relates transverse wrench faulting and tectonic wedging to promontory-promontory collision; Silurian syncollisional deformation, metamorphism and magmatism of the rocks of the Central mobile belt in Cape Breton and Southwestern Newfoundland.

The article focuses on study with formation of Shirenshan block and its relationship with Luoluan fault with the study of Mesozoic intracontinental orogeny of the north Qinling. It mentions geological mapping with structural analysis and other conventional construction methods and vorticity analysis and tectonic chronology test. It also mentions analyze shear type, formation time and the protolith or metamorphic ages and strain decomposition theory.

Includes a supportive view of Zheng-xiang Li's tectonic model for continent-continent collision between the North and South China blocks. Requirements for a nonsynchronous collision; Conflicting views on the need for a promontory for the South China block.

Eight paleostress stages are established in the Jurassic-Cretaceous Huangshan Basin based on fault-slip analysis and age estimation. The first six stages correspond to the subduction of the Paleo-Pacific Plate or the northward motion of the Philippine Block along the southeastern active margin of the South China Block: (1) the 169–162 Ma strike-slip regime was caused by westward low-angle subduction of the Paleo-Pacific Plate, which resulted in NNE-striking folds and top-to-the west thrusting along the southeastern margin of the Huangshan Basin; (2) the 156–125 Ma NW-SE extensional regime was triggered by slab break-off of the Paleo-Pacific Plate. This extension led to Early Cretaceous magmatism, deposition of Early Cretaceous sediments and development of normal faults along the northern boundary of the Huangshan Basin; (3) the 125–107 Ma strike-slip regime was induced by the N-S collision between the Philippine and South China blocks. This tectonic event caused the angular unconformity between the Upper and Lower Cretaceous and the inversion of the Early Cretaceous extensional basin; (4) the 105–86 Ma WNW-ESE extensional regime resulted from an off-shore arc jump of the subducted Paleo-Pacific Plate. This extension triggered the deposition of the Late Cretaceous Qiyunshan Formation; (5) the 86–80 Ma strike-slip regime was induced by high-angle subduction of the Pacific Plate after the off-shore arc jump. This event led to regional uplift and an unconformity at the base of the Late Cretaceous Xiaoyan Formation; (6) the 80–36 Ma N-S extensional regime was caused by the extension following the collision between the Philippine and South China blocks, corresponding to the deposition of the Late Cretaceous Xiaoyan Formation. The last two paleostress stages were the consequences of the far-field effect of the India-Asia continent-continent collision to the southwest of the South China Block: (7) the 36–30 Ma strike-slip regime was caused by the India-Asia collision. It is recorded by conjugate strike-slip faults and NW-striking thrust faults in the Huangshan Basin; (8) the 28–16 Ma ENE-WSW extensional regime resulted from subsequent post-collisional extension. This extension generated NW-striking normal faults in the Huangshan Basin and elsewhere in the eastern margin of Asia. The results of our paleostress inversion support that the Late Mesozoic to Cenozoic tectonic evolution of southeastern China is characterized by alternating strike-slip and extensional regimes. [ABSTRACT FROM AUTHOR]