Songnen Zhangguangcai Range Massif Research Articles

Geochronology, geochemistry, and geological significance of early Jurassic intrusive rocks in the Lesser Xing'an- Zhangguangcai Range, northeast China.

The Lesser Xing'an-Zhangguangcai Range of northeast China is located in the eastern segment of the Central Asian Orogenic Belt (CAOB), which records intense magmatism during the Mesozoic. The petrogenesis and geodynamic setting of the Early Jurassic intrusive rocks in this region are unclear. In this paper, we present new zircon U-Pb age and whole-rock geochemical data for these intrusive rocks to investigate their origins and tectonic setting. Zircon U-Pb dating suggests these intrusive rocks were emplaced during the Early Jurassic (197-187 Ma). The granites are enriched in silica and alkali, and depleted in MgO and CaO. They are metaluminous to weakly peraluminous, and have high A/CNK values and low zircon saturation temperatures (TZr ~ 779°C), suggesting they are highly fractionated I-type granites derived by partial melting of lower crustal materials. The granites exhibit negative Nb, Ta, P, Eu, and Ti anomalies due to fractional crystallization. The diorites and gabbros have low SiO2 contents and high Mg# values, and are enriched in light rare earth and large-ion lithophile (Ba, K, and Sr) elements, and depleted in heavy rare earth and high field strength (Nb, Ta, and Ti) elements. The geochemical characteristics show that the mafic magmas were derived by partial melting of mantle that had been metasomatized by subduction-related fluids. Based on the geochemical characteristics of coeval intrusive rocks and the regional geological setting, we suggest the Early Jurassic intrusive rocks in the Lesser Xing'an-Zhangguangcai Range were formed along an active continental margin, possibly as a result of bidirectional subduction of the Mudanjiang Oceanic plate between the Jiamusi and Songnen-Zhangguangcai Range massifs.

Late Paleozoic Tectonic Evolution of the Northern Great Xing’an Range, Northeast China: Constraints from Carboniferous Magmatic Rocks in the Wunuer Area

Northeast China composes the main part of the Central Asian Orogenic Belt. Traditionally, Northeast China has been considered a collage of several microcontinental blocks. However, the tectonic evolution of these blocks remains uncertain. Igneous rocks can be used to infer the magmatic histories of the blocks and thus help reconstruct their evolution. In this study, we present new zircon U–Pb and whole-rock geochemical data for Carboniferous igneous rocks from the Wunuer area, northern Great Xing’an Range, Northeast China, to constrain the Carboniferous amalgamation of the united Xing’an–Erguna and Songnen–Zhangguangcai Range massifs. On the basis of zircon U–Pb dating results, we identify two main stages of magmatism, i.e., early Carboniferous (332–329 Ma) and late Carboniferous (312–310 Ma). The early Carboniferous igneous rocks include diorites and granodiorites, with the former being classified as calc-alkaline to tholeiitic and the latter as tholeiitic. Both rock types are enriched in Th and U and depleted in Nb and Ti. The rocks display slightly fractionated rare earth element (REE) patterns, with an enrichment in light REEs and a depletion in heavy (H)REEs. The geochemical characteristics of the early Carboniferous rocks indicate that they formed in a subduction-related continental-arc setting. The late Carboniferous igneous rocks include monzogranites and syenogranites, both of which are classified as high-K calc-alkaline rocks and show enrichment in Th, U, and Rb and depletion in Nb and Ti. The rocks display strongly fractionated REE patterns, with an enrichment in light REEs and a depletion in HREEs. The geochemical characteristics of the late Carboniferous rocks indicate that they formed in a syn-collisional tectonic setting. Combining the new geochronological and geochemical results and inferred tectonic settings with regional magmatic data, we propose a new three-stage model to interpret the late Paleozoic tectonic evolution of the united Xing’an–Erguna and Songnen–Zhangguangcai Range massifs of Northeast China: (1) early Carboniferous (360–340 Ma) subduction of the Paleo-Asian oceanic plate beneath the united Xing’an–Erguna Massif and formation of the Wunuer oceanic basin in the Yakeshi area; (2) early to late Carboniferous (340–310 Ma) sustained subduction of the Paleo-Asian oceanic plate beneath the united Xing’an–Erguna Massif and initiation of subduction of the Wunuer oceanic basin; and (3) late Carboniferous–early Permian (310–275 Ma) syn-collisional to post-collisional tectonic transition between the united Xing’an–Erguna Massif and the Songnen–Zhangguangcai Range Massif.

Magma-mixing origin for the Early Jurassic intrusive rocks in the eastern Songnen–Zhangguangcai Range Massif, NE China: Evidence from geochronology, geochemistry and Hf–O–Sr–Nd isotopes

Granites containing abundant dioritic enclaves are widespread in the Songnen–Zhangguangcai Range Massif (SZRM). However, the role of mantle- and crust-derived magmas in the petrogenesis of the dioritic enclaves is debated. We present new zircon U–Pb–Hf–O isotopic compositions, whole-rock geochemistry, mineral geochemistry, and Sr–Nd isotopic compositions of hornblendites and dioritic enclaves and their host granites to elucidate their origins and investigate crust–mantle hybridization. Zircon U–Pb dating suggests that these intrusive rocks were emplaced during the Early Jurassic (197–186 Ma). The geochemical characteristics of hornblendites are similar to those of the Early Jurassic mafic–ultramafic rocks in the Lesser Xing’an–Zhangguangcai Range. They yield low (87Sr/86Sr)i ratios (0.704266–0.704324), high εNd(t) values (3.87–3.91), and are enriched in Ba, Sr, and K and depleted in Nb, Ta, and Ti, suggesting that they were derived from the partial melting of mantle wedge metasomatized by sediment melt. The host granites have high SiO2 (>65.12 wt%) and low MgO (<1.92 wt%) and Al2O3 (<16.23 wt%) contents and are to metaluminous–peraluminous high-K calc-alkaline rocks. In addition, they yield positive zircon εHf(t) values (3.42–7.58), zircon δ18O values (4.87‰–5.85‰) and whole-rock εNd(t) values (0.10–0.44), suggesting that the granitic magma originated from the partial melting of continental crust with the involvement of mantle-derived melts. The field and petrographic observations and geochemical analyses indicate that the enclaves were derived from magma mixing and mingling. The dioritic enclaves contain K-feldspar megacrysts and back-veins, and plagioclase crystals within them are reversely zoned and have ocellar textures. The weighted mean ages of the host granites (186 ± 3 and 188 ± 2.3 Ma) are similar to those of the dioritic enclaves (186 ± 1.8 and 188 ± 1.1 Ma). The major element contents of the intrusive rock are linearly correlated with the SiO2 contents, and the whole-rock geochemical and isotopic characteristics of the hornblendites and host granites show that they are the mafic and felsic end-members, respectively, involved in the magma mixing. Therefore, we propose that underplating by mantle-derived magma likely triggered partial melting of the continental crust to produce felsic magma, and the dioritic enclaves were formed by the mixing and mingling of mantle- and crust-derived magma alongside melting, assimilation, storage, and homogenization. This suggest that the Mudanjiang Oceanic crust was subducted westward beneath the SZRM during the Early Jurassic.

A synthesis of geochemistry of Mesozoic igneous rocks in NE China and tectonic superposition and transformation of the easternmost Central Asian Orogenic Belt

As the product of the amalgamation of multiple microcontinental massifs, Northeast China is located in the easternmost segment of the Central Asian Orogenic Belt (CAOB), which underwent multi-stage tectonic superposition in Mesozoic. Extensive and intensive igneous activities occurred throughout northeast China and the related igneous rocks can be considered as an effective probe for constraining tectonic evolution. In this study, numerous available ages and geochemical data are collected from published literature. The spatial-temporal distribution, rock assemblage, and geochemical characteristics of Mesozoic igneous rocks are systematically reassessed and summarized. A conclusion is drawn that NE China experienced the superposition and transformation of the Paleo-Asian Ocean (PAO) domain, the Mongol-Okhotsk Ocean (MOO) domain, and the Paleo-Pacific Ocean (PPO) domain in Mesozoic and detailed tectonic evolution is presented as follows. Firstly, NE China was under the joint effect of the MOO and the PAO during Early-Middle Triassic (ca. 252–237 Ma). Arc-type igneous rocks in the Erguna-Xing’an Block were induced by the southward subduction of the MOO Plate and adakites with high Sr/Y and (La/Yb)N ratios in the south segment of NE China were emplaced in the post-collision orogenic environment related to the closure of the PAO. Secondly, during Late Triassic, the influence of the PAO domain was gradually weakened, and igneous activities developed sporadically along the Solonker-Xar Moron-Changchun-Yanji suture zone. The MOO continued to subduct south until the Early Jurassic (ca. 220–190 Ma), and continental igneous rocks with arc-like features were widely distributed in the Erguna-Xing’an Block. During ca. 220–200 Ma, the Jiamusi-Khanka Massif was slipped away from the Songnen-Zhangguangcai Range Massif and this progress may be related to the PPO domain. Thirdly, in the Early Jurassic-Early Cretaceous (ca. 200–120 Ma), NE China came under the joint influence of the MOO and PPO tectonic domains. The subduction and closure of the MOO Plate and corresponding thickening of the lower crust resulted in widespread and intensive igneous activities in the Erguna and the Great Xing’an Range (GXAR). Two-stage subduction of the PPO and between which a period of change of subduction direction, induced the two-stage arc igneous activities of ca. 185–164 Ma and ca. 135–120 Ma, and the magmatic hiatus between ca. 163.5–135 Ma in the Zhangguangcai Range (ZGCR) and its east. Fourthly, the influence of the MOO domain was completed at ca. 120 Ma and numerous volcanic rocks corresponding chemically to A-type granite began to erupt violently, due to the rollback of the Paleo-Pacific oceanic slab. Since then, NE China has been completely under the control of the PPO domain.

Early Paleozoic magmatic events in the Bureya Continental Massif, Central Asian Orogenic Belt: Timing and tectonic significance

The Bureya Massif is one of the largest continental massifs in the eastern Central Asian Orogenic Belt. The reconstructions of tectonic scenarios for the evolution of this belt are mainly based on geochronological and geochemical data. However, relevant data from the Bureya Massif are scarce. Here, we report whole-rock geochemistry, zircon U-Pb geochronology, and Lu-Hf isotope data for Early Paleozoic granite intrusions to constrain the timing of the magmatic and tectonic processes in the Bureya Massif. Geochronological data yielded ages of 495 ± 5, 486 ± 8, 471 ± 6, 453 ± 2, and 426 ± 6 Ma for the granitoids in the Bureya Massif. The chemical composition of the Early Paleozoic granitoids mostly showed affinities to A-type (A2-subtype) granites. Furthermore, they have zircon εHf(t) values of −5.3 to +5.7, and two-stage model ages tHf(C) of 1.52–0.95 Ga. These results suggest that the parental magmas of the Early Paleozoic granitoids were derived either from melting of a dominantly Neo- and Mesoproterozoic crustal source. Early Paleozoic magmatism in the Bureya and Songnen–Zhangguangcai Range massifs was characterized by similar timing and identical Hf-in zircon isotope compositions. Additionally, both arrays contain early Neoproterozoic granitic intrusions and Early Cambrian and Ordovician sedimentary units, suggesting that they were part of a single continental massif at the beginning of the Cambrian or even in the Neoproterozoic. In this case, the tectonic nature of the Early Paleozoic magmatism in these two massifs should be the same and was probably related to the docking of the Jiamusi Massif.

Tectonic affinity of the Khanka Massif in the easternmost Central Asian Orogenic Belt: evidence from detrital zircon geochronology of Permian sedimentary rocks

ABSTRACTThe tectonic affiliation of the Khanka Massif, in the easternmost section of the Central Asian Orogenic Belt (CAOB), is still a matter of debate. Here, we provide new constraints on the provenance and timing of deposition of Permian strata in the western margin of the Khanka Massif. The results, which include U–Pb dating of detrital zircon grains using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), provide evidence regarding the tectonic position of the Khanka Massif and its role in the late Palaeozoic evolution of the eastern CAOB. Detrital zircon grains from a sublitharenite (Pingyangzhen Formation), a litharenite (Liangzichuan Formation), and a metamorphic siltstone (Qinglongcun Group) yielded multiple age populations ranging from Neoproterozoic (~914 Ma) to Permian (~272 Ma). Combined with age constraints from overlying/late-stage igneous rocks and other magmatism of the Khanka Massif, we conclude that the dated strata were deposited during the early–middle Permian and were sourced from the Khanka Massif. A comparison between the detrital zircon age populations and the history of magmatic activity in the neighbouring areas suggests that the Khanka Massif was tectonically linked to the Songnen–Zhangguangcai Range Massif. Based on tectonic discrimination diagrams, we conclude that the western margin of the Khanka Massif was positioned in a convergent-boundary basin during the early–middle Permian. Strike-slip faulting along the Dunhua–Mishan Fault, in response to ridge subduction of the Paleo-Asian Ocean Plate, resulted in a north-eastward movement of the Khanka Massif. The occurrence of Precambrian detrital zircon grains (with ages of 1900–1700 and 900–700 Ma) implies the presence of an ancient basement within the Khanka Massif.

Early-Middle Ordovician intermediate-mafic and ultramafic rocks in central Jilin Province, NE China: geochronology, origin, and tectonic implications

Magmatic and metasomatic rock suites can be commonly found in active convergent margins as the suprasubduction zone mantle wedge is usually impregnated by melts and fluids. Here we present petrologic, whole-rock geochemical and zircon U-Pb and Lu-Hf data from metamorphic intermediate-mafic and ultramafic rocks in central Jilin Province, NE China, to constrain the Early Paleozoic tectonic evolution of the southeastern margin of the Xing’an-Mongolia Orogenic Belt. Lithologically, the meta-igneous rocks are composed of plagioclase-actinolite, meta-allgovite, tremolitized pyroxenite, and serpentinized peridotite. Geochronological results indicate that the protoliths of the meta-igneous rocks formed during the Early–Middle Ordovician (474–466 Ma). Geochemical features suggest that the rocks are calc-alkaline and transitional-series rocks relatively enriched in large-ion lithophile and light rare earth elements and depleted in high field strength and heavy rare earth elements, implying that they formed in a supra-subduction zone environment. Additionally, the protoliths of the plagioclase-actinolites, which display an affinity for sanukites, resulted from an equilibrium reaction between mantle peridotite and slab melts derived from the partial melting of subducting sediments during early-stage subduction; the meta-allgovite rocks were likely derived from a juvenile depleted lithospheric mantle that was metasomatized by subduction-related fluids; the ultramafic rocks are magmatic cumulates formed in a suprasubduction zone mantle wedge. Furthermore, the meta-allgovite rocks display both arc-like and MORB-like geochemical characteristics, suggesting an intra-continental back-arc basin setting. These features, combined with the presence of the abundance of zircon xenocrysts with Neoproterozoic–Paleozoic ages, as well as the results of previous studies, reflect that a small-scale and limited back-arc basin, which was related to the northward subduction of the Paleo-Asian oceanic plate, probably existed close to the Songnen-Zhangguangcai Range Massif during the Early–Middle Ordovician.

Provenance and tectonic implications of Cambrian sedimentary rocks in the Bureya Massif, Central Asian Orogenic Belt, Russia

In this paper we present new detrital zircon U–Pb ages and Lu–Hf isotopic data as well as whole-rock geochemical data for siltstones of the Cambrian Chergilen and Allin formations in the Mel’gin Trough of the Bureya Massif, Russia. Our aim is to constrain the provenance and tectonic settings of these strata. The detrital zircons in these rocks are dominantly Neoproterozoic in age (∼80% of all zircons), along with some Mesoproterozoic and Paleoproterozoic zircons, and the main age peaks are at ca. 1.78, 1.64, 1.45, 1.18, 0.94, and 0.82 Ga. The zircon Hf and whole-rock Sm–Nd isotopic compositions, together with geochronological data, show that the main sources of the Cambrian sediments were Neoproterozoic and Mesoproterozoic igneous complexes formed by the reworking of Paleoproterozoic rocks. The main age populations of detrital zircons from the Cambrian siltstones in the Bureya Massif are similar to those of detrital zircons from the Neoproterozoic and early Paleozoic deposits within the Jiamusi Massif, suggesting that they share a common history. However, the crustal basements of the Bureya and Jiamusi massifs are different from those of other massifs in the eastern part of the CAOB, such as the Erguna, Khanka, Khingan, and Songnen–Zhangguangcai Range massifs. The wide Neoproterozoic magmatic events suggest that the Bureya and Jiamusi massifs have an affinity to the Tarim Craton or the northern Tian Shan block, different from the North Asian and North China cratons.

Petrology, geochemistry, and zircon U–Pb–Hf isotopes of Late Triassic enclaves and host granitoids at the southeastern margin of the Songnen–Zhangguangcai Range Massif, Northeast China: Evidence for magma mixing during subduction of the Mudanjiang oceanic plate

We report zircon U–Pb ages and geochemistry (major and trace elements, mineral compositions, and Hf isotopic compositions) for the Hailin pluton in the southeastern Songnen–Zhangguangcai Range Massif, northeastern China, to constrain the role of magma mixing in its petrogenesis and to reconstruct the tectonic evolution of the Mudanjiang Ocean. Zircon U–Pb dating yields ages of 215 ± 1 Ma, 217 ± 1 Ma, and 219 ± 1 Ma for the host granitoids of the Hailin pluton, and 221 ± 1 Ma for mafic microgranular enclaves (MMEs) within the granitoids, indicating they were emplaced coevally. The host granitoids are characterized by 63.18–70.44 wt% SiO2 and 0.69–1.94 wt% MgO, and are depleted in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs), and enriched in large ion lithophile elements (LILEs; e.g., Rb, Sr, and Ba) and light rare earth elements (LREEs). The zircons in the host granitoids yield two-stage model ages of 1058 Ma to 1770 Ma, together with εHf(t) values of −6.6 to +3.1. These results indicate that the host granitoid magmas were generated by partial melting of Mesoproterozoic lower crust contaminated by ancient crustal material. The MMEs have a restricted SiO2 range (47.61–57.4 wt%), high contents of Ni, Co, and Cr, and high Mg# values (42–54). They have higher Fe2O3T, MgO, Cr and Co contents than the host granitoids, as well as higher total rare earth element (REE) concentrations. Their REE patterns are sub-parallel to those of the host granitoids, characterized by enrichments in LILEs and LREEs, and depletions in HFSEs and HREEs. Zircons from two samples of the MMEs yield single-stage Hf model ages of 666–1077 Ma and εHf(t) values of −5.4 to +5.2. The geochemical characteristics of the MMEs are similar to those of the host granitoids, indicating crust-mantle interaction during their formation. The mafic magmas were derived from melting of depleted lithospheric mantle that had been metasomatized by slab-derived fluids. MMEs are common in the host granitoids and are characterized by irregular spheroidal shapes, with sharp, rounded, or irregular transitional contacts, acicular apatites, and plagioclase reverse zoning, suggesting the importance of magma mixing during petrogenesis. Our geochemical and isotopic data suggest that the Late Triassic Hailin pluton formed by the mixing of felsic and mafic magmas in an active continental margin setting, closely related to the westward subduction of the Mudanjiang oceanic plate beneath the Songnen–Zhangguangcai Range Massif.

Geochronology and geochemistry of Late Devonian-Carboniferous igneous rocks in the Songnen-Zhangguangcai Range Massif, NE China: Constraints on the late Paleozoic tectonic evolution of the eastern Central Asian Orogenic Belt

This paper presents new zircon U–Pb ages and Hf isotopic data, and whole–rock geochemical data for Late Devonian–Carboniferous igneous rocks from the Songnen–Zhangguangcai Range Massif (SRM), NE China, to constrain the late Paleozoic tectonic evolution of the eastern Central Asian Orogenic Belt and the nature of the crust beneath the SRM. LA–ICP–MS zircon U–Pb dating reveals two stages of magmatism in the Late Devonian (366Ma) and Carboniferous (325–313Ma). The Late Devonian magmatic event produced alkali feldspar granites with high SiO2 and total alkali contents, as well as pronounced negative Eu anomalies, similar to A-type granites. Based on these features, their high zircon εHf(t) values (+9.6 to +13.0), and the early Paleozoic tectonic evolution of the eastern SRM, we conclude that the primary magma for the Late Devonian granites was generated by partial melting of juvenile lower crust in a post-collisional extensional environment. The Carboniferous magmatic event produced a suite of intermediate–felsic igneous rocks. The intermediate rocks, including basaltic andesite, andesite, and quartz monzodiorites, have low SiO2 contents, high Mg#, high Cr, Co, and Ni contents, and display arc-like trace element characteristics. Based on these observations and their high zircon εHf(t) values (+5.8 to +10.7), we suggest their primary magma was derived from partial melting of depleted mantle, metasomatized by subduction-related fluids. The felsic rhyolites and monzogranites have high SiO2 contents, low Mg#, extremely low Cr, Co, and Ni contents, and zircon εHf(t) values of +10.5 to +13.7 and +4.2 to +6.9, respectively. These results indicate that the primary magma for the felsic rocks was derived from partial melting of heterogeneous juvenile crust. The Carboniferous igneous rock assemblages, together with coeval carbonate sedimentary formations, record an intra-plate extensional setting. The zircon εHf(t) data of Paleozoic igneous rocks from the eastern SRM define a temporal trend that is consistent with tectonic evolution. The increase in εHf(t) values during the early late Paleozoic age mirrors changes in magma source, corresponding to a switch from subduction–collision to post-collision tectonic regimes in the SRM. The zircon Hf isotopic compositions of the studied Late Devonian–Carboniferous igneous rocks record crustal accretion in the eastern SRM during the Neoproterozoic–early Paleozoic. Reworking of these crustal materials occurred in a post-collisional extensional environment during the late Paleozoic.

Convergence history of the Jiamusi and Songnen-Zhangguangcai Range massifs: Insights from detrital zircon U-Pb geochronology of the Yilan Heilongjiang Complex, NE China

The Heilongjiang Complex, located between the Jiamusi and Songnen-Zhangguangcai Range massifs, has become a focus of tectonic research in recent years. Here we document new U-Pb detrital zircon age data for metasedimentary rocks from the Heilongjiang Complex in Yilan-Huanan counties. These data not only provide important constraints on the depositional timing and provenance, but also give further insights into the complicated convergence history of the Jiamusi and Songnen-Zhangguangcai Range massifs. Most zircons from the Heilongjiang Complex show “magmatic-like” zircon rare earth element patterns, with enrichment in heavy rare earth elements and positive Ce and negative Eu anomalies, suggesting a magmatic origin. Laser ablation-inductively coupled plasma-mass spectrometry zircon U-Pb analysis indicates that the youngest detrital zircons in these metasedimentary rocks have concordant 206Pb/238U ages of ca. 230–180Ma. Based on this finding and the Middle Jurassic metamorphic ages of the Heilongjiang Complex, we conclude that metasedimentary rocks of the Yilan Heilongjiang Complex were deposited during the Late Triassic-Early Jurassic. Approximately 55% of the detrital zircons yield ages of 297 to 180Ma, with peaks at 270–245Ma, 230–200Ma and 200–180Ma, while 27% of the detrital zircons yield ages of 544–412Ma with a peak at 500–480Ma. Proterozoic detrital zircons (~15%) were also identified, yielding ages of 2352 to 595Ma, with most being of Neoproterozoic age. These results, combined with field relationships and previously published ages, suggest that detrital zircons in the Yilan Heilongjiang Complex were sourced mainly from igneous rocks in the Jiamusi and Songnen-Zhangguangcai Range massifs. Moreover, the protoliths of the metasedimentary rocks in the Yilan Heilongjiang Complex were most likely deposited in a forearc basin setting during convergence between the Jiamusi and Songnen-Zhangguangcai Range massifs.

Geochronology and geochemistry of early Paleozoic intrusive rocks from the Khanka Massif in the Russian Far East: Petrogenesis and tectonic implications

This paper presents new geochronological and geochemical data for early Paleozoic intrusive rocks from the Khanka Massif in the Russian Far East, with the aim of elucidating the Paleozoic evolution and tectonic attributes of the Khanka Massif. New U–Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages: ~502, ~492, 462–445, and ~430Ma. The ~502Ma pyroxene diorites contain 58.28–59.64wt% SiO2, 2.84–3.69wt% MgO, and relatively high Cr and Ni contents. Negative εHf(t) values (−1.8 to −0.4), along with other geochemical data, indicate that the primary magma was derived from partial melting of mafic lower crust with the addition of mantle material. The ~492Ma syenogranites have high SiO2 and K2O contents, and show positive Eu anomalies, indicating the primary magma was generated by partial melting of lower crust at relatively low pressure. The ~445Ma Na-rich trondhjemites display high Sr/Y ratios and positive εHf(t) values (+1.8 to +3.9), indicating the primary magma was generated by partial melting of thickened hydrous mafic crust. The ~430Ma granitoids have high SiO2 and K2O contents, zircon εHf(t) values of −5.4 to +5.8, and two-stage model ages of 1757–1045Ma, suggesting the primary magma was produced by partial melting of heterogeneous Proterozoic lower crustal material. The geochemistry of these early Paleozoic intrusive assemblages indicates their formation in an active continental margin setting associated with the subduction of a paleo-oceanic plate beneath the Khanka Massif. The εHf(t) values show an increasingly negative trend with increasing latitude, revealing a lateral heterogeneity of the lower crust beneath the Khanka Massif. Regional comparisons of the magmatic events indicate that the Khanka Massif in the Russian Far East has a tectonic affinity to the Songnen–Zhangguangcai Range Massif rather than the adjacent Jiamusi Massif.

Early–Middle Ordovician volcanism along the eastern margin of the Xing’an Massif, Northeast China: constraints on the suture location between the Xing’an and Songnen–Zhangguangcai Range massifs

ABSTRACTWe present new zircon U–Pb and Hf isotopic as well as whole-rock geochemical data for volcanic rocks from the eastern margin of the Xing’an Massif, Northeast China, in order to further our understanding of the suture location between the Xing’an and Songnen–Zhangguangcai Range massifs. Zircon secondary ion mass spectrometry U–Pb dating indicates that the volcanic rocks formed during the Early–Middle Ordovician (473–463 Ma). Compared with the coeval Moguqi basalts (rare earth element [REE] = 171–183 ppm; εHf(t) = +0.3 to +2.7; TDM1 = 1074–977 Ma), the Duobaoshan andesites exhibit lower overall REE abundances (109–131 ppm) with relatively high heavy REE contents, stronger high-field-strength element depletion, higher εHf(t) values (+13.0 to +14.8), and much younger TDM1 ages (559–484 Ma). This suggests that the primary magma for the andesites was generated by the partial melting of a relatively depleted mantle wedge that was metasomatized by subduction-related fluids. The primary magma for the basalts in the Moguqi area was probably derived from the partial melting of a relatively enriched lithospheric mantle that was also modified by fluids sourced from a subducted slab. These interpretations suggest that the andesites in Duobaoshan formed in a newly accreted island arc setting, whereas the coeval basalts in Moguqi formed along an active continental margin. We therefore attribute the Early–Middle Ordovician volcanism along the eastern margin of the Xing’an Massif to the northwestward subduction of the Nenjiang–Heihe oceanic plate beneath the Xing’an Massif. Furthermore, considering coeval igneous activity in the southern parts of the Xing’an Massif, we suggest that a magmatic arc existed along the margin of the Xing’an Massif in the early Palaeozoic (490–420 Ma). We conclude that the location of the suture between the Xing’an and Songnen–Zhangguangcai Range massifs runs from Airgin Sum, via south of Xilinhot, to Ulanhot, Moguqi, Nenjiang, and finally Heihe.

Formation of the Permian Taipinggou igneous rocks, north of Luobei (Northeast China): implications for the subduction of the Mudanjiang Ocean beneath the Bureya–Jiamusi Massif

ABSTRACTControversy has long surrounded the tectonic framework and evolution of the Mudanjiang Ocean between the Bureya–Jiamusi–Khanka Massif and Songnen–Zhangguangcai Range Massif, which are located in the easternmost segment of the Central Asian Orogenic Belt. To address these issues, we present zircon U-Pb ages, geochemical data, and zircon Hf isotopic compositions of the Taipinggou amphibolite and metagabbro exposed along the boundary area of Bureya–Jiamusi Massif and Songnen–Zhangguangcai Range Massif. Magmatic zircons from the amphibolite and metagabbro yield 206Pb/238U ages of 267 ± 2 Ma and 264 ± 2 Ma, respectively, which are interpreted as protolith ages. The geochemical data of the amphibolite samples show transitional characteristics of calcalkaline to tholeiitic series, with high MgO concentrations (9.44–10.48 wt.%) and Mg-numbers (73–75). These samples are enriched in large ion lithophile elements (e.g. Rb, Ba, and K) and light rare earth elements and are depleted in high-field-strength elements (e.g. Nb, Ta, and Ti) and heavy rare earth elements, with εHf(t) values of −6.63 to −3.26. It is inferred that the parental magma originated from an enriched lithospheric mantle that had been metasomatized by fluids derived from subducted oceanic slab. During magma evolution, the magma that formed the amphibolite mainly experienced accumulation with a shallow-level evolutionary process involving fractional crystallization. The Taipinggou metagabbro samples are subalkaline series and also characterized by enrichment in large ion lithophile elements (e.g. Rb, Ba, and K) and light rare earth elements and by depletion in Nb–Ta–P–Ti, with εHf(t) values of −3.09 to +1.16. The Taipinggou metagabbro and amphibolite have similar geochemical and Hf isotopic compositions, indicating a common parental magma source but with different degrees of magmatic differentiation. Based on the new geochronological and geochemical data presented in this study, we propose that both the Taipinggou metagabbro and amphibolite formed in a Middle Permian continental arc setting, closely related to eastward subduction beneath the Bureya–Jiamusi Massif. Combined with previous studies and regional geological observations, we suggest that a double-side subduction model is favoured for the Late Palaeozoic–Early Mesozoic geodynamic processes along the boundary area of Bureya–Jiamusi–Khanka Massif and Songnen–Zhangguangcai Range Massif.

Age and geochemistry of Neoproterozoic granitoids in the Songnen–Zhangguangcai Range Massif, NE China: Petrogenesis and tectonic implications

This study presents new zircon U–Pb ages and geochemical data for Neoproterozoic granitoids in the Songnen–Zhangguangcai Range Massif (SZRM) of NE China. This dataset provides insights into the Neoproterozoic tectonic setting of the SZRM and the links between this magmatism and the evolution of the Rodinia supercontinent. The zircon U–Pb dating indicates that the Neoproterozoic magmatism within the SZRM can be subdivided into two stages: (1) a ∼917–911Ma suite of syenogranites and monzogranites, and (2) an ∼841Ma suite of granodiorites. The 917–911Ma granitoids contain high concentrations of SiO2 (67.89–71.18wt.%), K2O (4.24–6.91wt.%), and Al2O3 (14.89–16.14wt.%), and low concentrations of TFe2O3 (1.63–3.70wt.%) and MgO (0.53–0.88wt.%). They are enriched in the light rare earth elements (LREE) and the large ion lithophile elements (LILE), are depleted in the heavy REE (HREE) and the high field strength elements (HFSE; e.g., Nb, Ta, and Ti), and have slightly positive Eu anomalies, indicating that they are geochemically similar to high-K adakitic rocks. They have zircon εHf (t) values and TDM2 ages from −4.4 to +1.5 and 1915Ma to 1592Ma, respectively, suggesting that they were derived from a primary magma generated by the partial melting of ancient thickened lower crustal material. In comparison, the 841Ma granodiorites contain relatively low concentrations of Al2O3 (14.50–14.58wt.%) and K2O (3.27–3.29wt.%), relatively high concentrations of TFe2O3 (3.78–3.81wt.%) and the HREE, have negative Eu anomalies, and have zircon εHf (t) values and TDM2 ages from −4.7 to +1.0 and 1875 to 1559Ma, respectively. These granodiorites formed from a primary magma generated by the partial melting of ancient crustal material. The ∼917–911Ma magmatism within the SZRM is inferred to have formed in an orogenic setting, whereas the ∼841Ma magmatism formed in an anorogenic setting related to either a post-orogenic tectonic event or the onset of Neoproterozoic continental rifting. It is proposed that the microcontinental massifs within the eastern central Asian orogenic belt of NE China formed during or following the final stage of assembly of Rodinia before rifting away from the Tarim Craton in response to the Rodinia breakup.

Permian tectonic evolution of the Mudanjiang Ocean: Evidence from zircon U-Pb-Hf isotopes and geochemistry of a N-S trending granitoid belt in the Jiamusi Massif, NE China

A combined study of LA-ICP-MS zircon U-Pb dating and geochemical analyses (major and trace elements, and Hf isotopic compositions) for five Permian granitic plutons (Mingyi, Tuoyaozi, Mengjiagang, Hengtoushan, and Qingbei plutons) from the Jiamusi Massif was carried out to determine their ages, petrogenesis, and tectonic evolution. The studied granitic plutons are composed of syengranites, monzogranites, and granodiorites, and they were emplaced in the Early-Middle Permian (278–263Ma). These granitic plutons are mostly high-K calc-alkaline and weakly peraluminous, and show consistent correlations of different oxides versus SiO2. They are all enriched in large ion lithophile elements (e.g., Rb, Th, K) and light rare earth elements, and depleted in high field strength elements (e.g., Nb, Ta, Ti) and heavy rare earth elements. And they have relatively homogeneous Hf isotopic compositions, with εHf(t) values varying from −6.16 to +2.95 and two-stage model ages ranging from 1681 to 1111Ma. According to their emplacement ages, geochemical characteristics, and Hf isotopic compositions, we conclude that these granitoids might be originated from parental magmas with similar compositions but evolved different degrees of fractionation, and their magmas were derived from the partial melting of amphibolite-facies mafic lower crust. These data, combined with previous studies on contemporaneous magma-tectonic activities in the Jiamusi Massif and Songnen-Zhangguangcai Range Massif, indicate that two paralleled N-S trending Permian magmatic belts are distributed in these two massifs. The eastwards subduction of the Mudanjiang oceanic plate beneath the Jiamusi Massif induced crustal melting to produce the studied Permian N-S trending granitoids in the Jiamusi Massif. Furthermore, westwards subduction of the Mudanjiang oceanic plate beneath the Songnen-Zhangguangcai Range Massif gave rise to Permian magmatism along eastern margin of the Songnen-Zhangguangcai Range Massif. Taken together, we suggest that the Jiamusi Massif and Songnen-Zhangguangcai Range Massif were not collided before the Permian, and a double-side subduction model is favored for the tectonic evolution of the Mudanjiang Ocean during the Permian.

Age and geochemistry of the Neoproterozoic granitoids in the the Songnen – Zhangguangcai Range Massif, NE China: Petrogenesis and tectonic implications

The Songnen–Zhangguangcai Range Massif (SZRM) is located in the eastern Central Asian Orogenic Belt and crops out over an extensive part of NE China. The massif was originally thought to contain numerous Precambrian terranes (e.g., Xingdong, Dongfengshan, Yimianpo and Zhangguangcailing groups). However, more recent zircon U–Pb dating indicates that the majority of these so‐called Precambrian sedimentary and igneous rocks actually formed during either the Paleozoic or Mesozoic and contain only minor Precambrian components (Wang et al., 2014). The presence of Neoproterozoic and Paleoproterozoic detrital zircons with magmatic origins from and Paleozoic units of the SZRM indicating that this area occurs Proterozoic magmatism (Wang et al., 2014), whereas no Proterozoic magmastism has been found. Recently, Pei et al. (2007) reported the ca. 1800 Ma magmastism, as evidenced by the data of exploration drillholes in the southern Songliao basin. However, an alternative view is that the basement within the SZRM is predominantly Phanerozoic, as evidenced by the presence of Paleozoic fossils and comparatively rare geochronological data (Guo and Liu, 1985; Wu et al., 2011), meaning that the ca. 1800 Ma rocks in this area may be a tectonically emplaced slice of the North China Craton (Zhang et al., 2005). All of this means that the age and nature of the SZRM basement, and whether this area records Neoproterozoic magmatism, remain unclear.This study presents new geochronological, whole‐rock geochemical, and zircon Hf isotopic data for early Proterozoic granitoids within the eastern margin of the SZRM of NE China. These data provide insights into the Neoproterozoic tectonic setting of the SZRM and the links between this magmatism and the evolution of the Rodinia supercontinent.The zircon U–Pb dating indicates that the Neoproterozoic magmatism within the SZRM can be subdivided into two stages: (1) a ∼917–911 Ma suite of syenogranites and monzogranites, and (2) an ∼841 Ma suite of granodiorites. The 917–911 Ma granitoids contain high concentrations of SiO2 (67.89–71.18 wt.%), K2O (4.24–6.91 wt.%), and Al2O3 (14.89–16.14 wt.%), and low concentrations of TFe2O3 (1.63–3.70 wt.%) and MgO (0.53–0.88 wt.%). They are enriched in the light rare earth elements (LREE) and the light ion lithophile elements (LILE), are depleted in the heavy REE (HREE) and the heavy field strength elements (HFSE; e.g., Nb, Ta, and Ti), and have slightly positive Eu anomalies, indicating they are geochemically similar to high‐K adakitic rocks. They have zircon εHf (t) values and TDM2 ages from −4.4 to +1.5 and from 1915 Ma to 1592 Ma, respectively, suggesting they were derived from a primary magma generated by the partial melting of ancient thickened lower crustal material. In comparison, the 841 Ma granodiorites contain relatively low concentrations of Al2O3 (14.50–14.58 wt.%) and K2O (3.27–3.29 wt.%), relatively high concentrations of TFe2O3 (3.78–3.81 wt.%) and the HREE, have negative Eu anomalies, and have zircon εHf (t) values and TDM2 ages from −4.7 to +1.0 and from 1875 to 1559 Ma, respectively. These granodiorites formed from a primary magma generated by the partial melting of ancient crustal material. The ∼917–911 Ma magmatism within the SZRM is inferred to have formed in an orogenic setting, whereas the ∼841 Ma magmatism formed in an anorogenic setting related to either a post‐orogenic tectonic event or the onset of Neoproterozoic continental rifting. It is proposed that the microcontinental massifs within the SZRM formed during or following the final stage of assembly of Rodinia before rifting away from the Tarim Craton in response to Rodinia breakup.

Geochronology and geochemistry of early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East

The Russian Far East and Northeast (NE) China are located in the eastern part of the Central Asian Orogenic Belt (CAOB), which consists of a series of micro‐continental massifs including the Erguna, Xing'an, Songnen–Zhangguangcai Range, Bureya, Jiamusi, and Khanka massifs. The Khanka Massif is located in the easternmost part of the CAOB, mainly cropping out in the territory of Russia, with a small segment in NE China. To the north and west of the Khanka Massif are the Jiamusi and Songnen–Zhangguangcai Range massifs, respectively. The boundary between these massifs is marked by the Dunhua–Mishan Fault. To the south lies the North China Craton, and to the east is the Sikhote–Alin Orogenic Belt separated by the Arsenyev Fault.However, the early Paleozoic evolution and tectonic attributes of the Khanka Massif are debated. These conflicting ideas result from the lack of systematic research on early Paleozoic igneous rocks from the Russian part of the Khanka Massif.It is generally accepted that the CAOB represents the largest known Phanerozoic accretionary orogenic belt. However, questions remain concerning the nature of the deep crust beneath the Khanka Massif, and whether Precambrian crust exists within the massif itself.In this paper, we report new zircon U–Pb ages, Hf isotopic data, and major‐ and trace‐element compositions of the early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East, with the aim of elucidating the early Paleozoic evolution and the tectonic attributes of the Khanka Massif, as well as the nature of the underlying deep crust.New U–Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages: ∼502 Ma, ∼492 Ma, 462–445 Ma, and ∼430 Ma.The ∼502 Ma pyroxene diorites show negative Eu anomalies, and the ∼492 Ma syenogranites, intruding the ∼502 Ma diorites, show positive Eu anomalies. These observations indicate that the primary parental magmas of these rocks were derived from different origins.The 462–445 Ma magmatism is made up of syenogranites and tonalites. The ∼445 Ma Na‐rich tonalites contain low REE concentrations, and are enriched in Eu and Sr. These observations, together with the positive εHf(t) values, indicate that they were derived from magmas generated by partial melting of cumulate gabbros.The ∼430 Ma I‐type granodiorites and monzogranites from the northern Khanka Massif, and the A‐type monzogranites from the central Khanka Massif display zircon εHf(t) values ranging from −5.4 to +5.8. This suggests that they formed from magmas generated by partial melting of heterogeneous lower crustal material.Zircon Hf isotopic data reveal the existence of Precambrian crustal material within the Khanka Massif. The geochemistry of the Middle Cambrian intrusive rocks is indicative of formation in an extensional setting, while Late Cambrian–middle Silurian magmatism was generated in an active continental margin setting associated with the subduction of a paleo‐oceanic plate beneath the Khanka Massif. Regional comparisons of the magmatic events indicate that the Khanka Massif has a tectonic affinity to the Songnen–Zhangguangcai Range Massif rather than the Jiamusi Massif.

Late Paleozoic tectonic evolution of the central Great Xing'an Range, northeast China: geochronological and geochemical evidence from igneous rocks

We present zircon U–Pb and Hf isotopic and whole‐rock geochemical data for late Paleozoic igneous rocks in the central Great Xing'an Range, northeast China, to constrain the late Paleozoic amalgamation history of the united Xing'an–Erguna and Songnen–Zhangguangcai Range massifs. Based on zircon U–Pb dating, we ascertain three main stages of magmatic events: Late Devonian (381–364 Ma), early Carboniferous (360–341 Ma), and late early Carboniferous–early Permian (328–271 Ma). Late Devonian rhyolites originated from partial melting of Meso‐proterozoic accreted lower crust. The crust‐derived rhyolites and coeval mantle‐derived basalts constitute a bimodal volcanic association in the west. Early Carboniferous igneous rocks include syenogranites, monzogranites, gabbro diorites, and gabbros. The granitoids are derived from partial melting of Meso‐proterozoic accreted lower crust. The gabbros and gabbro diorites show the spatial variation in zircon εHf(t) values (−0.53 to +0.84 in the east and +12.3 to +13.5 in the west), which imply that they were mainly derived from metasomatized mantle wedge and asthenosphere mantle, respectively. These characteristics indicate that northwest‐towards high‐angle subduction of the Paleo‐Asian Ocean plate beneath the united Xing'an–Erguna Massif induced arc magmatism in the east and back‐arc magmatism (similar to back‐arc rift) in the west during the Late Devonian to early Carboniferous. Late early Carboniferous–early Permian sub‐alkaline and alkaline igneous rocks are characterized by multiple sources, such as the depleted mantle, juvenile lower crust, and thickening lower crust. Their temporal variations in geochemical characteristics imply that the central Great Xing'an Range was situated under a transitional setting from syn‐collisional to post‐collisional during the late early Carboniferous to early Permian. Using the combined insight from lithofacies palaeogeography and regional magmatisms, we suggest amalgamation of the united Xing'an–Erguna and Songnen–Zhangguangcai Range massifs occurred during the late early Carboniferous to late Carboniferous. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Geochronology and geochemistry of late Paleozoic–early Mesozoic igneous rocks of the Erguna Massif, NE China: Implications for the early evolution of the Mongol–Okhotsk tectonic regime

We undertook geochemical and geochronological studies on late Paleozoic–early Mesozoic igneous rocks from the Erguna Massif with the aim of constraining the early evolution of the Mongol–Okhotsk tectonic regime. Zircon crystals from nine representative samples are euhedral–subhedral, display oscillatory growth zoning, and have Th/U values of 0.14–6.48, indicating a magmatic origin. U–Pb dating of zircon using SIMS and LA–ICP–MS indicates that these igneous rocks formed during the Late Devonian (∼365Ma), late Carboniferous (∼303Ma), late Permian (∼256Ma), and Early–Middle Triassic (246–238Ma). The Late Devonian rhyolites, together with coeval A-type granites, formed in an extensional environment related to the northwestwards subduction of the Heihe–Nenjiang oceanic plate. Their positive εHf(t) values (+8.4 to +14.4) and Hf two-stage model ages (TDM2=444–827Ma) indicate they were derived from a newly accreted continental crustal source. The late Carboniferous granodiorites are geochemically similar to adakites, and their εHf(t) values (+10.4 to +12.3) and Hf two-stage model ages (TDM2=500–607Ma) suggest they were sourced from thickened juvenile lower crustal material, this thickening may be related to the amalgamation of the Erguna–Xing’an and Songnen–Zhangguangcai Range massifs. Rocks of the late Permian to Middle Triassic suite comprise high-K calc-alkaline monzonites, quartz monzonites, granodiorites, and monzogranites. These rocks are relatively enriched in light rare earth elements and large ion lithophile elements, and depleted in heavy rare earth elements and high field strength elements. They were emplaced, together with coeval porphyry-type ore deposits, along an active continental margin where the Mongol–Okhotsk oceanic plate was subducting beneath the Erguna Massif.