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This article presents U–Th–Pb and Lu–Hf detrital zircon isotope data, as well as whole-rock Sm–Nd isotope data on metasedimentary rocks from the eastern part of the Tukuringra Terrane. Our analyses show that the zircons in metasedimentary rocks are mostly early Mesozoic. The Early Mesozoic, Early Paleozoic and Neoproterozoic zircons are predominant and Early Precambrian zircons are almost absent in these rocks. The age of the youngest zircon population places a lower age limit of sedimentation at 204 Ma for the Tungala Formation (Upper Triassic, Rhaetian), at 181 Ma for the Dugda Formation (Lower Jurassic, Toarcian), and at 189 Ma for the Tangomen Formation (Lower Jurassic, Pliensbachian). Practically all Mesozoic, Paleozoic, and Neoproterozoic zircons are characterized by Neo- and Mesoproterozoic Hf-model ages (tHf(DM)) = 1.41–0.46 Ga, tHf(C) = 1.55–0.49) and Mesoproterozoic Nd-model ages (tNd(DM) = 1.25–1.10 Ga, tNd(C) = 1.31–1.14). These results indicate that the sedimentary rocks were mainly sourced from the Amur continental superterrane, but not from the southern framing of the North Asian Craton. [ABSTRACT FROM AUTHOR]

Precise timing of granitoids and constraints of their magma sources are critical to understanding the subduction–collision tectonic evolution of the Altun orogenic belt (AOB), a vital part of the Qinghai-Tibet plateau in northwestern China. We provide in-situ zircon U–Pb age, Hf isotopic composition and whole-rock geochemistry of the Yusupualeke granitic pluton in the South Altun orogenic belt (SAOB), an integral unit of the AOB, to determine the tectono-magmatic evolution of the SAOB at early Palaeozoic. The Yusupualeke granitic pluton comprises the medium-coarse grained porphyritic monzogranite and medium-fine grained granodiorite. The monzogranite sample yielded a weighted mean 206Pb/238U age of 476.8 ± 3.6 Ma (MSWD = 0.59), while the granodiorite yielded a weighted mean 206Pb/238U age of 453.2 ± 4.7 Ma (MSWD = 0.013). Zircon U–Pb ages suggest that the subduction–collision process of the SAOB remained from the middle stage of the early Palaeozoic to the end. Both of the studied granitoids belong to metaluminous to weakly peraluminous series and show typical I-type granite characteristics with depletions in Ba, Nb, Sr, P, and Ti, and enrichments in light rare earth elements (LREEs), Rb, Th, K, and slightly negative Eu anomalies. Based on the geochronological data and regional geological background, we believe that the porphyritic monzogranites were formed during the northward subduction process of the South Altun ocean (SAO), while the granodiorites were formed during the tectonic regime transition stage. Besides, combing the previous research achievements with our newly obtained data, we put forward a new division and geodynamic model of the early Palaeozoic tectono-magmatic evolution for the South Altun orogenic belt. [ABSTRACT FROM AUTHOR]

This work presents the whole-rock elemental geochemistry and Sr − Nd isotopes and zircon Hf − O isotopes for dikes from Tagaolemiao and Tuilamamiao, the southern margin of the southeast Central Asian Orogenic Belt (SE CAOB), to explore their origin and dynamic setting. Zircon U − Pb dating reveals that the Tagaolemiao dikes emplaced at ca. 242 Ma and the Tuilamamiao dikes emplaced at ca. 250 Ma, which postdated the Late Permian magmatic lull and convergent events in the SE CAOB. Dikes from the two areas are I-type rhyolitic rocks and exhibit high SiO 2 , low MgO, and low Cr, Co, and Ni contents. The Tagaolemiao dikes have depleted zircon Hf (ε Hf (t) = +3.75 to +9.82), whole-rock Sr − Nd (I Sr (t) = 0.704340–0.704855; ε Nd (t) = +1.3 to +2.1) isotopic composition and variable zircon δ18O values (4.88–7.29‰), and were derived from the mixing melts of the juvenile crust and depleted mantle. In contrast, the dikes from Tuilamamiao show negative zircon ε Hf (t) (−2.33 to −10.85) and whole-rock ε Nd (t) (−6.7 to −15.5) values, low I Sr (t) (0.706640–0.708208) and high δ18O (6.38–7.61‰) values, which originated from the partial melting of the old continental lower crust. The Triassic dyke swarms from this work indicate the SE CAOB switched into an intra-continental extension tectonic setting after the Paleozoic long-term accretion-convergence. • Early-Middle dikes were derived from the thickened lower crust. • Triassic dyke swarms reveal an intra-continental extension setting. • Vigorous mantle perturbation is important to the Triassic tectonics in the SE CAOB. [ABSTRACT FROM AUTHOR]

It is broadly accepted by researchers that the North China Craton (NCC) was linked with the Pangea supercontinent by the Central Asian Orogenic Belt (CAOB) resulted from the final closure of the Paleo Asian Ocean (PAO), but when and how still be controversial, such as one-sided subduction and continental collision, or double-sided subduction and soft collision, the ocean basin closed in the Devonian or Late Permian and so on. We conducted zircon U-Pb-Hf isotopes analyses of 5 Paleozoic sedimentary samples which collected along the Bainaimiao area, locates at the northern margin of the NCC, and compared their zircon U-Pb isotopic ages and εHf(t) values with those former published data in the north orogenic belt (NOB) and the south orogenic belt (SOB) to trace provenance differences between the NOB and SOB. Our sedimentary samples have several prominent age peaks at circa 270 Ma, 460 Ma, 1350 Ma, 1750 Ma and 2500 Ma, respectively, and cover different εHf(t) values in different age peaks, which have shown complex tectonic evolution of the NCC and the Bainaimiao arc belt. In our comparison, the Neo-Proterozoic zircons are common seen in the NOB data, but rare in the SOB data, and Devonian zircons from the NOB have mostly shown positive εHf(t) values while most of which from the SOB are negative, which mean that the NOB magmatism events in Paleozoic period had formed juvenile crust but the SOB magmatism events in temporary period result from reworking of older crust according to detrital zircon ages and relevant εHf(t) values. In addition, trace elements analysis of the detrital zircons, such as U, Hf, Y, Th, Yb and so on, was also used to help distinguishing the tectonic setting of the formation of these zircons. Our data shows that most Paleozoic zircons have lower Y concentration and higher U/Yb (>0.1) ratios, which can be inferred that these zircons may crystalized in continental magmatic setting, which supports the viewpoint that the oceanic crust of the PAO subducted beneath the NCC in the Paleozoic to form and transform the Bainaimiao arc belt. In summary, we use detrital zircons geochronology and trace elements analyses to outline Paleozoic magmatic events occurred in the northern margin of the NCC, to discuss the attribute of the Bainaimiao arc belt, and imply that there was no material exchange between the NOB and the SOB in the Paleozoic, namely, the PAO oceanic basin still remained open until the Permian, and the eastern segment of the CAOB may finally formed after the Paleozoic. [ABSTRACT FROM AUTHOR]

Considerable controversy concerns the consumption and closure processes of the North and South Altyn Oceans resulting in the formation of the North Altyn Tagh subduction-accretion belt and the South Altyn Tagh subduction-collision belt in the Altyn Tagh orogen in southeastern Tarim. This study focused on U–Pb ages and Hf isotopes of detrital zircons from early Paleozoic sedimentary rocks in the Central Altyn Tagh terrane. Our dating results revealed that the studied sedimentary rocks were deposited at ca. 467–429 Ma. The predominant early Paleozoic detrital zircons demonstrate negative εHf(t) values, highlighting their derivation from the coeval intermediate-felsic magmatic rocks sourced from ancient supracrustal materials with enriched isotopes. These inferred, enriched intermediate-felsic magmatic rocks were probably generated in different consumption and closure processes of the North and South Altyn Oceans, based on geochronology and geochemistry of the early-middle Paleozoic intermediate-felsic magmatic rocks in the Altyn Tagh orogen. A number of ca. 520–490 Ma detrital zircons were primarily derived from the coeval, enriched intermediate-felsic magmatic rocks in the local Central Altyn Tagh terrane and the adjacent North Altyn Tagh subduction-accretion belt associated with the advancing subduction of the North Altyn Ocean. The ca. 490–470 Ma detrital zircons are most prominent and suggest a derivation from the coeval, enriched magmatic rocks subject to the rollback of the North Altyn Ocean. These inferred magmatic rocks might have once existed in the region but have been intensely exhumed to be source material for the studied sedimentary rocks. A few ca. 450 Ma detrital zircons indicate a provenance from the North Altyn Tagh subduction-accretion belt during collision after the final closure of the North Altyn Ocean. In contrast, some ca. 470–460 Ma detrital zircons were probably derived from the coeval intermediate- to felsic-magmatic rocks in the Central Altyn Tagh terrane during the exhumation stage of the deep continental collision after the final closure of the South Altyn Ocean. Combination of provenance study and magmatic record provides potential to establish complicated orogenic evolution. [ABSTRACT FROM AUTHOR]

Earth's evolution involves deep, hot rocks rising upward by convection to near-surface environments, as well as the unique scenarios such as the formation and breakup of Gondwana and Pangea. These processes have been well recorded by the widely distributed magmatism. To understand the tectonic evolution and Gondwana assembly, we compiled early Paleozoic zircon U–Pb ages (n = 67), in-situ zircon Hf isotopes (n = 1011), and bulk-rock elemental compositions (n = 293) and Sr–Nd isotopes of magmatic rocks in the Tibetan–Himalayan orogen. Three stages of Paleozoic magmatism were identified here, including early (>490 Ma) to middle (490–470 Ma) to late (<470 Ma) stages, in response to the final assembly of the Gondwana supercontinent. Early-stage magmatic rocks are characterized by highly variable SiO 2 (48.0–80.0 wt%) and MgO (0.02–9.65 wt%) contents with Mg# range from 5.4 to 78, K 2 O/Na 2 O ratios ranging from 0.14 to 2.81, and whole-rock Sr–Nd (87Sr/86Sr(i) (0.7035–0.7340), ε Nd (t) (-9.5–+1.0)) and zircon Hf (ε Hf (t) = –15 to + 8.0) isotopic compositions with significant mantle contributions; they could be generated in an Andean-type arc setting along the active northern continental Gondwana margin. Middle-stage magmas were dominated by fertile continental crustal signatures (SiO 2 > 70 wt%, A/CNK > 1.10, MgO < 2.69 wt%) in a crustal thickening setting. Late-stage magmas also have highly variable Si, Mg and isotopic components, with coeval mantle-derived magmas developing in an extensive setting. Importantly, the widespread presence of early Cambrian to late Ordovician peraluminous high-K calc-alkaline magmatism in the Tibetan–Himalayan orogen indicates that the reworking of ancient continental crustal materials played a key role in reconstructing and stabilizing the final Gondwana assembly. [ABSTRACT FROM AUTHOR]

The late Paleozoic tectonic framework of the southeastern Central Asian Orogenic Belt is key to restricting the accretion orogeny between the Siberia Craton and the North China Craton. To clarify the framework, petrogenesis of early Permian intrusive rocks from southeastern Inner Mongolia was studied. Zircon U‐Pb dating for bojite and syenogranite from Ar‐Horqin indicate that they were emplaced at 288–285 Ma. Geochemical data reveal that the bojite is highly magnesian and low‐K to middle‐K calc‐alkaline, with E‐MORB‐type REE and IAB‐like trace element patterns. The syenogranite is a middle‐K calc‐alkaline fractionated A‐type granite and shows oceanic‐arc‐like trace element patterns, with depleted Sr‐Nd‐Hf isotopes, (87Sr/86Sr)I = 0.7032–0.7042, εNd(t) = +4.0 to +6.6 and zircon εHf(t) = +11.14 to +14.99. This suggests that the bojite was derived from lithospheric mantle metasomatized by subducted slab melt, while the syenogranite originated from very juvenile arc‐related lower crust. Usng data from coeval magmatic rocks from Linxi–Ar‐Horqin, the Ar‐Horqin intra‐oceanic arc was reconstructed, i.e., initial transition in 290–280 Ma and mature after 278 Ma. Combined with regional geological and geophysical materials in southeastern Inner Mongolia, an early Permian tectonic framework as 'one narrow ocean basin of the PAO', 'two continental marginal arcs on its northern and southern' and 'one intra‐oceanic arc in its southern' is proposed. [ABSTRACT FROM AUTHOR]

Plagiogranites are a volumetrically minor component of oceanic crust and ophiolites, but offer an opportunity to probe the processes and mechanisms by which felsic crusts were produced from the mafic oceanic crusts. The Qinling-Tongbai orogenic belt in central China is a typical composite orogenic belt that records the amalgamation processes between the North China Block and the South China Block. The Erlangping unit represents an accretionary oceanic unit in the Qinling-Tonbai orogenic belt and contains minor plagiogranites, which have received little attention. In this study, we carried out an integrated study of U–Pb geochronology and Hf–O isotopes in zircon, as well as whole-rock isotope and geochemical analyses for felsic rocks in the Erlangping unit. These rocks occur as dikes to stocks intruding ambient basalts. They have relatively high Na 2 O and Al 2 O 3 , moderate MgO and low K 2 O contents, and are classified as oceanic plagiogranites. Zircon U–Pb geochronology yielded formation ages of ca. 465 Ma. Zircon δ18O compositions (4.4–5.1‰) are lower than or similar to those of zircons from normal mantle. The low TiO 2 content, elevated Zr/Hf, and light rare-earth element (LREE) enrichments in these rocks indicate that these plagiogranites were generated by partial melting of hydrothermally altered oceanic crust. These samples have more depleted whole-rock ε Nd (t) (+4.4 to +5.1) and zircon ε Hf (t) (+10.5 to +12.8) values than the basaltic wall-rocks, implying they were derived from a newly accreted oceanic arc. Taking into account the tectonic framework of the broader Qinling Orogenic belt, a subduction-induced magma flare-up in the Ordovician could have triggered the anatexis of the existing Erlangping oceanic arc, and in turn generated these plagiogranites. Partial melting of oceanic crust that has been enriched in a subduction system may be an important mechanism for the formation and maturation of continental crust in oceanic arc settings. • Plagiogranite dikes and stokes in the Erlangping unit were emplaced at ca. 465 Ma. • The plagiogranites were formed by partial melting of lower oceanic crust. • Subduction induced the anatexis of the existing Erlangping oceanic arc. • Partial melting of ocean crust is important for the maturation of continental crust. [ABSTRACT FROM AUTHOR]

The geologic history of the Western Tianshan region is important for understanding the evolution of the Central Asian Orogenic Belt and accretionary orogenesis. Paleozoic and Mesozoic igneous rocks are present along the northern margin of the Yili Block; however, studies of Paleozoic subduction and collisional events have been relatively limited. Published geochronologies of Middle Devonian magmatic rocks in this region are also lacking. Therefore, this study analyzed the zircon U–Pb ages and major and trace elemental compositions of three granite types collected from Biezhentao Mountain (Wenquan County, Western Tianshan). The medium-grained diorite (384.1 ± 3.6 Ma) and diorite–porphyrite (382 ± 3.2 Ma) are silica-rich, weakly peraluminous, alkali-rich, enriched in large-ion lithophile elements, depleted in high field strength elements, and belong to the calc–alkaline series, with A-type granite characteristics. The monzogranite (423.3 ± 9.4 Ma) exhibits A-type granite characteristics and belongs to the peraluminous calc–alkaline series. The findings suggest that the granitoids recorded two stages of tectonomagmatism during the Middle Devonian–Late Silurian. The Middle Devonian medium-grained diorite and diorite–porphyrite formed in a back-arc extensional setting, whereas the Late Silurian monzogranite formed in an active continental margin setting during the subduction of the North Tianshan Ocean. These results provide insights into the tectonic and magmatic processes that occurred during the evolution of the Western Tianshan region and the formation and evolution of the Central Asian Orogenic Belt. [ABSTRACT FROM AUTHOR]

This paper presents the results of U–Pb dating of detrital zircons from six metasedimentary rocks in the Taowan and Kuanping groups in the northern margin of the North Qinling Orogenic Belt (NQB), Central China, for constraining the tectonic affinity of the NQB, the existence time and tectonic features of the Kuanping Ocean and the accurate northern boundary of the NQB. Zircon U–Pb dating indicates that the protoliths of the two metasedimentary rocks from the upper and lower parts of the Taowan Group were deposited later than ∼1111 and ∼871 Ma respectively. However, the protoliths of the four metasedimentary rocks from different layers of the Kuanping Group were deposited later than ∼781, ∼668, ∼515 and ∼477 Ma, respectively, suggesting that the Taowan Group and the Kuanping Group both have an abnormal or non-Smithian stratigraphic sequence. The age populations and predominant peak ages of detrital zircon grains from the Mesoproterozoic–middle Neoproterozoic metasedimentary rocks in the Taowan and Kuanping groups indicate that their provenances were mainly attributed to the NQB and subordinately from the Yangtze Craton (YZC), suggesting that the two groups both belong to the NQB and the northern boundary of the NQB should be placed to the north of the Taowan Group, which can be called the Paleo-Luonan–Luanchuan Fault. However, the Nd–Pb whole-rock isotopes, zircon Hf isotopes and trace element compositions of the Precambrian basement rocks and the Neoproterozoic granitic magmatic events in the NQB are significantly different from those in the YZC, suggesting that the NQB was more likely to be an independent microcontinent adjacent to the YZC from the Mesoproterozoic to the Neoproterozoic, and experienced a unique geological history. On the other hand, together with the record of the oldest MORB-type basalt with an age of 1445 Ma in the Kuanping Group, the first late Mesoproterozoic sedimentary record (∼1111 Ma) in the Taowan Group, to be reported using precise geochronological data in this study, it indicates that the Kuanping Ocean separated the NQB from the NCC that had already existed to the north of the NQB before the Mesoproterozoic, and was a major ocean basin which had lasted for a long time, rather than as a back-arc basin. [ABSTRACT FROM AUTHOR]

Abstract The South Tianshan Orogenic Belt (STOB) occupies the southwestern margin of the Central Asian Orogenic Belt (CAOB), and is the key region to understanding the Paleozoic evolution of the southern part of the Palo-Asian Ocean. Here we present an integrated study of zircon U–Pb ages, whole-rock major and trace elements and Sr–Nd isotopes on Silurian and Late Carboniferous intermediate-felsic intrusions exposed in the Oxidaban area located in the South Tianshan region in Xinjiang, NW China. The Silurian intrusion is composed of quartz diorite, granodiorite and monzogranite, whereas the Late Carboniferous rocks include granite porphyry and granite porphyry enclaves. LA–ICP–MS zircon U–Pb dating yields ages of 426.8 ± 4 Ma for quartz diorite and 424.5 ± 4 Ma for monzogranite, respectively. The quartz diorite shows middle–K calcic and metaluminous affinity, and the granodiorite exhibits similar features, but peraluminous. They display enrichment in large-ion lithophile elements (LILEs) and depletion of high field strength elements (HFSEs) together with negative Eu anomalies, broadly comparable with typical arc-type rocks. They have similar Sr–Nd isotopic compositions, with a narrow range in (87Sr/86Sr) i of 0.70578 to 0.70644 and ε Nd (t) of −0.95 to −2.16. Based on geochemical and isotopic characteristics, we infer that the granodiorite is produced by fractional crystallization of quartz diorite rocks, which were dominantly produced by partial melting of medium to high–K basaltic protoliths. Besides, the monzogranite also exhibits arc-type geochemical signatures, which we correlate to partial melting of middle-lower juvenile crust and subsequent contamination by ancient crust during ascent and emplacement. Zircon LA–ICP–MS U–Pb analyses yielded crystallization ages of 300.4 ± 1.5 Ma for the granite porphyry and 304.8 ± 2.3 Ma for the granite porphyry enclave. These rocks are dominantly shoshonite and peraluminous, and are likely derived from partial melting of the greywacke mixed with minor pelitic components. The low Al 2 O 3 /TiO 2 (<100) ratios suggest a high temperature condition, which may be attributed to heat input from underplated mantle-derived magmas in the post-collision extension setting. Base on these scenarios, we propose that the bi-directional subduction of the South Tianshan Ocean occurred during the Early Paleozoic and the subduction polarity changed to northward during Middle Devonian, followed by the collision between Yili-Central Tianshan Block and Tarim Craton in the Late Carboniferous. Highlights • Silurian and Carboniferous felsic magmatic suite in the STOB. • Zircon U–Pb dating yields emplacement ages of ca. 425 Ma and ca. 300 Ma. • Southward subduction of the South Tianshan Ocean in the Early Paleozoic. • The final collision is constrained to have occurred before ca. 300 Ma. [ABSTRACT FROM AUTHOR]

Accretionary orogens are the primary sites for continental growth, but the rate and amount of crust generation throughout its evolution are poorly constrained. In this contribution, our new results about the genesis of two intermediate-felsic plutons are combined with a compiled granitoid dataset to evaluate the amount and rate of crustal growth throughout the evolution of the Western Kunlun orogen, which is a typical accretionary orogen associated with the consumption of the Proto-Tethys during the early Paleozoic. The ca.446 Ma Sanshili pluton was formed through interactions between metasomatized mantle wedge-derived oxidized magmas and the lower arc crust, as indicated by high whole-rock Mg#, high Ce4+/Ce3+ ratios (308–861) of ca.446 Ma zircons, and the existence of inherited zircons with ages of 546–472 Ma. The Yirba dioritic to granodioritic pluton was emplaced at 474 ± 3 Ma. Samples from the Yirba pluton are characterized by high K 2 O content, higher Mg# (40–49) than pure crustal melts, slightly higher Y + Nb concentrations, and high Th/Nb ratios, and slightly enriched to depleted Hf–Nd isotopes. Combined with the presence of the 502–531 Ma inherited zircons, the Yirba pluton is suggested to from through differentiation of the metasomatized lithospheric mantle derived-magmas beneath the juvenile intra-oceanic arc in combination with crustal reworking during regional extensions. The Yirba pluton, together with contemporary A 1 -type granites, thus marks an extension event at ca. 475 Ma in the Western Kunlun orogen. The compiled dataset reveals three magmatic flare-ups at 530–500 Ma, 480–470 Ma, and 445–430 Ma, corresponding to two slab rollback events and the slab break-off after the final closure of the Proto-Tethys. The three episodes of more intensive magmatism are associated with more radiogenic Hf–Nd isotopes and increased Nb/La and Nb/Y ratios, indicating more contributions from intraplate-like sources during lithospheric extensions. Meanwhile, element ratios (La/Yb, Sm/Yb, and Sr/Y) that are sensitive to crustal thickness are also elevated. These phenomena are consistent with rapid juvenile crust generation during extensional stages of accretionary orogens. Our study has also shown that the rate of new crust production is quite uniform for different extensional events. The crustal generation rate during slab break-off is much higher than that during slab rollback, although the proportions of juvenile inputs in granitoids formed during slab rollback are relatively higher. This may reflect extra inputs from partial melting of oceanic slabs and subducting sediments like those in continental collision zones and/or rapid asthenospheric upwelling coupled with enhanced crust reworking during slab break-off. • The Yirba pluton was formed at ca.475 Ma during regional extensions. • There are three magmatic flare-ups in the Western Kunlun orogen. • The crust generating rate is uniform for different extensional events. [ABSTRACT FROM AUTHOR]

The variations in source rocks and melting conditions of granites can provide essential clues for the crustal magmatic response in orogenic process. Based on geochronology, whole‐rock and mineral chemistry, this paper reveals two different granites in the Northern Qinling migmatite complex, which reveal obvious differences in source region and melting condition. The older granodiorite (402 ± 0.8 Ma) displays typical Na‐rich adakite affinity, i.e., high Na2O/K2O (2.04 to 2.64) and Sr/Y (96 to 117) ratios, they have relative evolved isotopic compositions (εNd(t) = –0.52 to –0.04; zircon εHf(t) = –0.06 to +7.78). The younger leucogranite (371 ± 2 Ma) displays higher SiO2 (72.32 to 73.45 wt%), lower (TFeO + MgO + CaO + TiO2) contents (<2 wt%) and depleted Sr‐Nd‐Hf isotopic compositions (i.e., εNd(t) = +2.6 to +3.0; zircon εHf(t) = +5.94 to +14.12), as well as high 10000 × Ga/Al and TFeO/MgO ratios, indicating that they represent highly fractionated I‐type granites that derived from melting of juvenile crust. The variations in source rocks and melting condition of the two granites indicating a tectonic switch from compression to extension in 400 to 370 Ma, this switch is later than that in the eastern section of the North Qinling, indicating a scissor collision process between the South Qinling and North China Craton (NCC) in Devonian era. [ABSTRACT FROM AUTHOR]

New whole-rock geochemical and detrital zircon U–Pb and Lu–Hf data of metasedimentary sequences of the Silvretta Nappe, Orobic Alps, Strona-Ceneri Zone, Gotthard Massif and Venediger Nappe are presented. These units seem to share a common early to middle Paleozoic geological record, which has alternatively been interpreted as the result of intraplate or orogenic processes. Detrital zircon data mainly indicate late Ediacaran to early Ordovician maximum sedimentation ages for the studied sequences, suggesting that they were intimately related to Cadomian and Cenerian orogenic processes along the northwestern Gondwana margin. The common presence of late Ediacaran to Cambrian Cadomian ages associated with variable subchondritic to suprachondritic Lu–Hf compositions points to recycling processes of Cadomian sequences, further supported by geochemical data indicating a relatively low to moderate maturity of sedimentary protoliths. The occurrence of Cenerian arc-related intrusions in Austroalpine and South Alpine basement unit points to an arc/back-arc position in the early Paleozoic Cenerian orogen, except for the Strona-Ceneri Zone, which was likely located closer to the forearc region, as indicated by the presence of high-pressure metamorphism. Younger sequences, such as the Landeck Quartz-phyllite, document post-Cenerian sedimentation, whereas those of the Venediger Nappe more likely record the early stages of Variscan subduction, as indicated by Devonian maximum deposition ages. [ABSTRACT FROM AUTHOR]

The tectonic evolution of the Qinling orogen is key to understanding the process of convergence between the North China Block (NCB) and the South China Block (SCB). The Wuguan Complex and Liuling Group, situated along the southern margin of the Shangnan–Danfeng suture zone (SDSZ) between the North Qinling Terrane (NQT) and the South Qinling Terrane (SQT), are important indicators of the late Paleozoic tectonic evolution of the Qinling orogen. In this paper, the detrital zircon U–Pb geochronology and geochemical analysis of the Wuguan Complex and Liuling Group are carried out. Detrital zircons from two metasedimentary rock samples of the Liuling Group yield a major age peak at 460 Ma and two subordinate peaks at 804 Ma and 920 Ma, with a few older grains having formed between 1000–2549 Ma. One metasedimentary rock sample of the Wuguan Complex has a similar age spectrum as that of the Liuling Group, which shows the main age peak at 440 Ma and two subordinate peaks at 786 and 927 Ma, indicating all detrital zircon age results have the same source area. Geochemical analyses suggest that the sedimentary rocks of the Liuling Group and part of the Wuguan Complex were deposited in the tectonic setting of the continental island arc (CIA), while the geochemical characteristics of the other group of sedimentary rocks of the Wuguan Complex indicate the mixing of basic rock sources. The protolith of garnet amphibolite and hornblende schist, which were collected from the Wuguan Complex, were classified as andesite and basalt, with the nature of arc andesite and oceanic island basalt, respectively. In combination with regional data, we suggest that the Liuling Group and the Wuguan Complex were deposited in a fore-arc basin. Additionally, the Wuguan Complex was subsequently incorporated into the tectonic mélange by the northward subduction of the Paleo-Qinling Ocean. Zircons from the subduction-related metamorphic igneous rocks in the Wuguan Complex yielded a weighted mean age of 365 ± 19 Ma, indicating that the Paleo-Qinling Ocean between the SQT and NQT was still subducted at the end of Devonian. [ABSTRACT FROM AUTHOR]

• The gneisses record two period metamorphic events as Neoproterozoic and early Paleozoic metamorphism. • 920–929 Ma from granitic gneisses and ca. 0.9 Ga from paragneisses represent the Neoproterozoic tectono-thermal event. • The early Paleozoic metamorphic ages given by the rim domains of zircons from gneiss samples record the the UHP-HP metamorphic evolution in EKO. The East Kunlun Orogen (EKO) is a long-lived accretionary orogenic belt that records the Paleozoic–Mesozoic amalgamation processes of the East Asia continent. The belt consists mainly of various kinds of gneisses with minor amounts of eclogite and garnet amphibolite occurring as lenses. We report zircon U–Pb ages and Hf–O isotopic compositions for the granitic gneisses and paragneisses in the Xiarihamu area near Golmud in Qinghai Province, to investigate the metamorphic history and evolution of the orogenic belt. For the granitic gneisses, zircon U–Pb chronology reveals a Neoproterozoic magmatic event and an early Paleozoic metamorphic event. The magmatic crystallization ages of the two granitic gneisses are 920 ± 6 and 929 ± 2 Ma, and yield ε Hf (t) values of −8.4 to 1.7 and δ18O values of 7.94–11.19‰, suggesting their derivation mainly from continental crustal materials. The detrital zircons from the paragneisses record a Neoproterozoic metamorphic event and a Paleozoic metamorphic event. Most of the detrital zircons from the two paragneiss samples yielded ages of 2.1–0.9 Ga, indicating that the sources of the sediment were formed mainly during the Neoproterozoic to Paleoproterozoic. These Neoproterozoic magmatic and metamorphic events suggest that the EKO underwent a Neoproterozoic tectonothermal event that was related to the assembly of the Rodinia supercontinent. The similar tectonic histories of the EKO and North Qaidam belt (NQB) indicate they were probably part of a single tectonic unit during the Neoproterozoic. Some of the zircons have metamorphic overgrowth rims yielding two stages of Paleozoic metamorphic ages of ca. 440 Ma (438 ± 2 Ma) and ca. 420 Ma (419 ± 6 Ma, 416 ± 6 Ma, and 423 ± 6 Ma). Combined the discover of high-pressure mineral inclusions (jadeite + quartz) in these rims with the results in previous studies, the ages of these rims (ca. 440 Ma and ca. 420 Ma) are suggested to represent of HP-UHP metamorphism of the EKO. These age data imply that the gneisses in this study might share common early Paleozoic metamorphic event with the HP–UHP eclogites in the EKO. [ABSTRACT FROM AUTHOR]

The tectonic evolution of the Qinling Orogenic Belt in the Late Paleozoic has long been controversial, especially due to the limitation of the Mianlue Ocean subduction time. Basin formation and sedimentary development in the southern North China Block are closely related to the tectonic evolution of the Qinling Orogenic Belt, which is an effective entry point to study basin–mountain interaction. We present new detrital zircon U–Pb data from the Shihezi Formation in the Luonan area in the southern margin of the North China Block. The results show that the bottom sample has two major peaks at 288 Ma and 448 Ma, with weak peaks at 908, 1912 Ma and 2420 Ma. The top sample has one major peak at 297 Ma, with weak peaks at 1933 Ma and 2522 Ma. Combined with the published paleocurrent data and lithofacies paleogeography, the sediments of the bottom sample were sourced from the North Qinling Belt, Inner Mongolia Palaeo-Uplift and the basement of the North China Block. The top sample originated mainly from the Inner Mongolia Palaeo-Uplift and the basement of the North China Block. Comparing the obtained zircon U-Pb ages with the published relevant data in the North China Block, it is found that the provenance area shifted from the Qinling Orogenic Belt to the Inner Mongolia Paleo-Uplift in the Late Carboniferous–Permian, and the Qinling Orogenic Belt could hardly provide provenance for the southern North China Block in the Middle Permian. The uplift of the Qinling Orogenic Belt in the Late Carboniferous may be the continuation of Caledonian orogeny in the Early Paleozoic, whereas the uplift of the Inner Mongolia Palaeo-Uplift is related to the tectonic evolution of the Central Asian Orogenic Belt during the Late Paleozoic. This tectonic transformation occurred when the Qinling Orogenic Belt no longer supplied sediments to the southern North China Block in the Middle Permian, and the Mianlue Ocean subduction did not occur until at least the Late Permian. [ABSTRACT FROM AUTHOR]

The article discusses a study on the oxide deposits from the Zircon SIMS U-Pb Age of the Shaxinan Melagabbro and assessment of Fe-Ti-V oxide mineralization. Topics include oxide deposit of the eastern Tianshan during the late Paleozoic period, regional study of Fe-Ti-V oxide metallogenic mechanism, and host of zircon grains analysis.

To better constrain the origin and drift history of the North Qiangtang terrane (NQT), we report a well‐dated paleomagnetic pole from the Late Permian volcanics of the NQT that appears to average out secular variation. Our new results yield a paleolatitude of −7.6 ± 5.6°N at ~259 Ma for our sampling area, which confirms the NQT drifted northward during the Permian and Triassic periods. The equatorial paleolatitude of the NQT is similar to that of the coeval South China block, demonstrating that they were in close proximity. Combined with palaeontological and magmatic evidence, paleomagnetic constraints on the drift of the NQT in the Permian indicate that the NQT moved northward together with the South China block at this time. The paleolatitude evolution of the NQT implies that the NQT rifted from the northern margin of the Gondwana in the Devonian, which is earlier than the departure time of the South Qiangtang terrane. Plain Language Summary: The Tibetan Plateau is composed of several different blocks that accreted to the southern margin of Asia. There are still several unanswered questions, such as the following: Where did these blocks originate? How did these blocks accrete to Asia? How did the oceanic basin evolve? In this work, we provide robust evidence to show that the Northern Qiangtang was located at equatorial latitude (−7.6 ± 5.6°N) during the Late Permian (~259 Ma). The northward drift history together with features of the Northern Qiangtang and South China block indicates that they moved northward together during the Permian and that the Northern Qiangtang rifted from the northern margin of the Greater India margin of Gondwana during the Devonian. Key Points: The North Qiangtang terrane (NQT) was located at equatorial paleolatitude (−7.6 ± 5.6°N) during the Late Permian (~259 Ma)The NQT drifted northward together with the South China block (SCB) during the PermianThe NQT rifted from the northern margin of Gondwana during the Devonian [ABSTRACT FROM AUTHOR]

U–Pb and Lu–Hf isotopic data of detrital zircons from late Paleozoic and Mesozoic strata along the southern flank of the Chinese western Tianshan enable to identify provenance changes and reconstruct early stage uplift and denudation history of the Tianshan range. Detrital zircons from Permian and Early–Middle Triassic siliciclastic rocks show two prominent age populations at 500–390 Ma and 310–260 Ma, and subordinate Precambrian ages at ~ 2.5 Ga, 2.0–1.7 Ga, 1.2–0.9 Ga and 900–600 Ma, with rare ages between 390 and 310 Ma. These characteristics and zircon ε Hf (t) data consistently suggest a sediment source predominantly from the Tarim Craton, rather than the Central Tianshan–Yili Block. In contrast, Late Triassic to Cretaceous strata additionally contain abundant 390–310 Ma and 260–220 Ma detrital zircons, implying multiple source regions from the Central Tianshan–Yili Block, Tarim Craton, and Western Kunlun Orogen. A significant switch of sedimentary provenances occurred in the mid-Triassic and is consistent with contemporaneous change of paleocurrent directions and the onset of intense tectonothermal events in the broad region of the Chinese western Tianshan and Kyrgyz Tianshan. These data collectively indicate that the significant surface uplift and denudation of the Tianshan range were probably initiated in the mid-Triassic (~ 240 Ma) after the assembly of the southwestern Central Asian Orogenic Belt. This uplifting event represents an intracontinental orogeny most likely in response to the collision between the Qiangtang Block and southern Eurasia, following the closure of the western part of the Paleo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

The eastern Tiklik belt is mainly composed of meta-sedimentary rocks of the Ailiankate and Sailajiazitage Groups that were previously interpreted as Palaeoproterozoic, Mesoproterozic and Neoproterozoic stratigraphic units, which are part of the Tarim Precambrian basement. Our new detrital (U-Pb) zircon ages yield a dominant single peak with a major range between ca. 700 Ma and 800 Ma for meta-sedimentary rocks from both the Ailiankate and Sailajiazitage Groups, which demonstrates that they were mainly derived from an independent Neoproterozoic terrane. There are several ages of 444–659 Ma, of which, the youngest has an age of 444 ± 6 Ma, indicating that the time of deposition of the meta-sedimentary rocks could have been in the Early Silurian. The porphyritic granite sample has a weighted mean crystallization age of 442 ± 2 Ma. The adakite-like geochemical characteristics of the porphytitic granite suggest derivation from the melting of the oceanic slab and formation in a subduction, arc-related tectonic setting. After integration with relevant published data, our work suggests that the Ailiankate and Sailajiazitage Groups belong to a tectonic mosaic that contains Middle Neoproterozoic extensional and Paleozoic accretionary and collisional complexes, rather than the Paleoproterozoic or Mesoproterozoic basement, as previously regarded. We propose a new tectonic model for the eastern Tiklik belt that started with a Middle Neoproterozoic extension and ended with Paleozoic continuous accretion and collision in a Paleo-Tethys archipelago, which contributed to the considerable continental growth of the southern Tarim Block. [ABSTRACT FROM AUTHOR]

• Part of uppermost basement in the West Kunlun Orogen is early Paleozoic. • Arc-related magmatism in the West Kunlun Orogen continuous during early Paleozoic. • Subduction retreating during Neoproterozoic and advancing during early Paleozoic. • Advancing subduction at 540–420 Ma likely responsible for closure of Proto-Tethys Ocean. The West Kunlun Orogenic Belt (WKOB) is a key area for evaluating the evolution of the Proto-Tethys Ocean. To constrain this history, we present geochemical and zircon U-Pb geochronological data from a suite of metasedimentary rocks within this orogenic belt. Detrital zircons ages are clustered between 1000 and 400 Ma, with major peaks at ca. 510 Ma and 460 Ma, and minor peaks at ca. 840 Ma and 650 Ma. The age groups younger than 1000 Ma broadly overlap magmatic activity at ca. 540–420 Ma and minor magmatism at 920–540 Ma in the WKOB. The age data also reveal Early Paleozoic metamorphic basement rocks in the WKOB that were probably sourced from Kunlun terranes and blocks of Gondwanan affinity rather than the Tarim Craton. Compiled geochemical data suggest a protracted subduction setting in the WKOB in the Early Paleozoic. εHf(t) values show increasing trends at 900–740 Ma and 740–600 Ma and a distinct decreasing trend at 540–420 Ma, consistent with retreating subduction during the Neoproterozoic and advancing subduction in the Early Paleozoic. The retreating-advancing subduction cycle in the WKOB was possibly related to the opening and closure of the Proto-Tethys Ocean along the margin of Gondwana. [ABSTRACT FROM AUTHOR]