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Typical ophiolitic rock assemblages such as siliciclastic rocks, basalts and gabbros, together with the subduction-related intermediate-acidic intrusive rocks, are newly discovered in the Tongjiang-Fuyuan area of the Heilongjiang Provence, NE China. To determine the formation age and genesis of the mafic rocks (basalts and gabbros) and intermediate-acidic intrusive rocks (granodiorites) in the area, as well as their geodynamic settings, the whole-rock geochemical analysis and zircon LA-ICP-MS U-Pb dating were carried out. Zircon U-Pb results suggest that the granodiorites are 93–95 Ma and gabbro is 95 Ma, respectively. Geochemical results show that the gabbros and basalts exhibit characteristics of ocean island basalt (OIB) affinity and are typically related to having originated from mantle plumes. While the granodiorites show the nature of the island-arc magmatic rocks and may originate from the lower crust. Based on the coeval igneous rock associations and regional tectonic evolution, we conclude that the late Cretaceous magmatic rocks in the Tongjiang-Fuyuan area are the product of continuous subduction of the Palaeo-Pacific plate and reflect the subduction rollback process of the Palaeo-Pacific plate. [ABSTRACT FROM AUTHOR]

There is a controversy regarding the amalgamation of Xing'an and Songnen Blocks along the Hegenshan‐Heihe Suture (HHS) in the eastern Central Asian Orogenic Belt (CAOB). To solve this problem, we performed detailed study on the granites from the Zhangdaqi area, adjacent to the north of the HHS in the northern part of the Great Xing'an Range, NE China. Geochemically, the granites in the study area are metaluminous‐weak peraluminous and high‐K calc‐alkaline series. Trace elements of the granites show that LREEs are relatively enriched, while HREEs are relatively deficient and obvious REE fractionation. The granites are characterized by obvious negative Eu anomalies, meanwhile, they are relatively enriched in Rb, K, Th and depleted in Ba, Nb, Sr, P, Ti. All the geochemical features suggest that the granites in the Zhangdaqi area are aluminum A‐type granites. The zircon LA‐ICP‐MS U‐Pb ages of these granites are 294–298 Ma, indicating that they formed in the Early Permian. These granites also have positive εHf (t) values (8.4–14.2) and a relatively young two‐stage model age between 449 Ma and 977 Ma, implying that the magma was derived from the re‐melting of the Early Paleozoic‐Neoproterozoic juvenile crust. Combined with geochemical characteristics (Nb/Ta ratios of 9.0–22.2, and Zr/Hf ratios of 52.3–152.0), we believe that the magmatic source area is a mixture of partial melting of the lower crust and depleted mantle. A‐type granites and bimodal volcanic rocks along the Hegenshan‐Heihe Suture formed during the Late Carboniferous‐Early Permian, indicating that the HHS between Xing'an and Songnen Blocks closed in the late Early‐Carboniferous. Subsequently, the Zhangdaqi area was in a post‐orogenic extensional environment from Late Carboniferous to Early Permian and resulted in the formation of the A‐type granites. [ABSTRACT FROM AUTHOR]

The Late Palaeozoic Solonker‐Xar Moron‐Changchun‐Yanji Suture (SXCYS) is considered to mark the location of the final closure of the Paleo‐Asian Ocean, which separated the North China Craton to the south and the amalgamated blocks to the north in Northeast China. There has always been controversy about its eastern extension in Northeast China and the final closure time of the Paleo‐Asian Ocean. To explore this issue, we collected gabbro and quartz‐diorite samples in the Hunchun area for the genesis of mafic magma and age dating, and five groups of Permian to Triassic sandstones belonging to both sides of the potential suture locations in the middle and east Jilin Province for the provenance analysis to discuss the final closure time of the Paleo‐Asian Ocean and the possible positions of the eastward termination of the SXCYS. The gabbro reveals a Middle Permian concordia average age of 266.9 ± 5.2 Ma, and the quartz diorite reveals a Late Permian Concordia average age of 258.8 ± 4.8 Ma. Lithological and geochemical analysis reveal the two rock samples belong to low‐K arc tholeiites from the oceanic island and calk‐alkaline volcanics from the active continental margin, respectively, which implies that during the middle to late Permian, the SW margin of the Jiamusi–Khanka Block (JB) continuously experienced the subduction process from the Paleo‐Asian Ocean Plate. The final closure time of the Paleo‐Asian Ocean should be later than the Late Permian. Meanwhile, four groups of sandstone from the east Jilin reveal typically Jiamusi–Mongolia Block (JMB) provenance features, with age components of ~500 Ma, ~0.9–1.5 Ga implying that the Wangqing, Hunchun, Kaishantun area belongs to the northern part of the SXCYS from late Early Permian to Middle Triassic, with youngest age components of 288.2 ± 2.8, 275.5 ± 1.8, 250 ± 1.7, and 244.9 ± 1.7 Ma, respectively. The late Early Permian sandstone from the middle Jilin reveals the youngest age component of 273.8 ± 3.4 Ma and the age component of 487 ± 3 Ma also revealing JMB feature. Comparing to previous studies, we propose that the Paleo‐Asian Ocean finally closed during Middle to Late Triassic. A possible ENE fault separates the eastern extension of SXCYS into two parts, which means the possible position of the eastward extension of the SXCYS should go along the Wangqing‐Kaishantun with NNW direction in the west, Hunchun‐Laoheishan with NW direction in the east. [ABSTRACT FROM AUTHOR]

New U–Pb age data and Hf isotope systematics on zircons from Middle Devonian and Lower Carboniferous units from NE China provide evidence for the depositional age of these poorly constrained units as well as for the timing of the collision between the Erguna (Ergun in some references) and Xing’an blocks in the eastern end of Central Asian Orogenic Belt (CAOB). The detrital zircons from the Devonian and Carboniferous sandstones yielded similar age spectra in probability diagrams showing three distinct peaks at ∼450 Ma, ∼500 Ma and ∼540 Ma, respectively, along with Proterozoic and Archean age groups, except for a relatively young age population at ∼360 Ma detected for zircons from the Hongshuiquan Fm. The dating results suggest that the depositional time of the Niqiuhe Fm. should be younger than Late Silurian, as indicated by the youngest 422-Ma detrital zircon from this Fm., and that of the Hongshuiguan Fm. with a youngest detrital age of ca. 338 Ma, is younger than Middle Mississippian (Visean), which is in accordance with those inferred from biostratigraphic data. These dominant age groups are widely found in the Erguna and Xing’an blocks, it is suggested that the sediments of the studied sandstones from Niuqiuhe and Hongshuiquan Fms come mainly from the Erguna and Xing’an blocks. The ε Hf ( t ) value of dated zircons from our sandstones has a wide range (−21 to 16), which shows a mixed signature of that from Paleozoic granitoids in Xing’an block (6–17) and Erguna block (−2 to 6), indicating that Erguna and Xing’an blocks had connected before the Middle Devonian deposition of the Niqiuhe Fm. (422 ± 5 Ma). Combined with the age data, we suggest that the Erguna and Xing’an blocks started to accrete at ∼540 Ma, reached the peak of collision at ∼500 Ma, and went into the post-collision stage from ∼490 to ∼450 Ma. The study provides more evidences and constraints for the early Paleozoic evolutions of the inter-continental block amalgamations and accretions in CAOB. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) is the largest accretionary orogen in the world with considerable Phanerozoic juvenile crustal growth. The eastern segment of the CAOB is occupied by NE China and its adjacent areas, which locates in a triangle area surrounded by Siberian Craton to the northwest, North China Craton (NCC) to the south and Pacific oceanic plate to the east. Therefore, the NE China is a key area to study the geological evolution of multiple tectonic systems and overprinting, which has become a hot research topic. In the past five decades, especially the last two decades, there have been many detailed geological investigations carried out and a lot of new data reported in NE China. A progress has been achieved in tectonic evolution, however, there are still many open questions and arguments dealing with the tectonic models, correlation of tectonic units, amalgamation of different blocks and their tectonic affinity. In this study, we did a detailed review of the tectonic evolution of NE China and regional comparison and correlation of the different tectonic units in the eastern segment of CAOB. We re-subdivided NE China into two old blocks of Erguna block (EB) and Jiamusi block (JB) with Precambrian basement and three accretionary terranes of Xing'an accretionary terrane (XAT), Songliao accretionary terrane (SAT) and Zhangguangcai accretionary terrane (ZGCAT), which are separated from each other by the Xinlin-Xiguitu suture (XXS), Hegenshan-Heihe suture (HHS), Longfengshan suture (LFS) and Mudanjiang-Yilan suture (MYS), respectively. The ZGCAT is dominantly composed of early Paleozoic magmatic arc materials and minor late Paleozoic igneous rocks with an old Yichun mini-block, while the SAT consists dominantly of the late Paleozoic magmatic rocks with two small old blocks of the Xilinhot and Longjiang mini-blocks. According to the tectonic correlation and comparation of different tectonic units, we established a new orocline tectonic model for the eastern CAOB: 1) the XAT and ZGCAT accreted to the southern (present position) margin of Ereendavaa-Erguna-Mamyn block (EEMB) and Bureya-Jiamusi-Khanka block (BJKB) with the closure of Xinlin-Xiguitu-Heilongjiang ocean during the early Paleozoic; 2) Subsequently, the SAT accreted to the southern (present position) margin of integrated XAT-ZGCAT terrane with the closure of Hegenshan-Nenjiang-Longfengshan ocean during the late Paleozoic. These initially W-E linear shaped accretionary orogenic belts were ultimately bent southward through Paleozoic time and constituted a huge Paleozoic orocline, NE China Orocline, which collided with NCC by a scissor-like style closure of Paleo-Asian Ocean (PAO) from west to east along the Solonker-Xar Moron-Changchun-Yanji suture (SXCYS) during the late Permian-middle Triassic. The NE China Orocline, together with Tuva-Mongol Orocline and Kazakhstan Orocline in the western CAOB, constituted a huge multiple orocline tectonic system in the CAOB during the Paleozoic era. Our study will contribute to the understanding on tectonic evolutions of CAOB and the NE Asian, and suggests that the orocline should be a common tectonic model for accretionary orogeny. • NE China consists of two Precambrian blocks and three Paleozoic accreted terranes. • A new orocline tectonic model is established for first time in NE China. • Blocks in NE China had been integrated in later Early Carboniferous. [ABSTRACT FROM AUTHOR]