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The Bangong–Nujiang suture zone (BNSZ) is the remnants of the Meso-Tethyan main oceanic basin in the Tibetan plateau. It is noted that several microcontinents, e.g., Amdo and Jiayuqiao, occur within the Meso-Tethyan ocean basin. These microcontinents were strongly reworked associated with the subduction and closure of this ancient ocean, thus they play a key role in understanding the evolution of this ocean. In this contribution, we report newly documented Early Jurassic gabbros (ca. 182–175 Ma) from the Amdo microcontinent in the middle segment of the BNSZ. The gabbros can be subdivided into two groups, i.e., OIB (ocean island basalt) and MORB (mid-ocean ridge basalt) groups. The OIB-group gabbros are characterized by highly enriched Nd Hf isotopic characteristics (zircon ε Hf (t) = −11.7 to −8.9; whole-rock ε Nd (t) = −11.0 to −10.1). They are geochemically similar to OIB and are interpreted to be products of the partial melting of a relatively deep mantle source (> 85 km) and subsequent continental crustal inputting. The MORB-group gabbros belong to the tholeiitic series and have similar compositions to those of MORB. They were most likely derived from a depleted mantle source (zircon ε Hf (t) = +3.7 to +16.5; whole-rock ε Nd (t) = +4.9 to +8.1) in a relatively shallow depth (< 85 km). Integrating previous studies with the data presented in this contribution, we suggest that the generation of coeval OIB- and MORB-like gabbros are related to lithospheric delamination after the Qiangtang-Amdo collision and the closure of the Bangong-Nujiang ocean basin. This result will give new constraint on the evolution of the Meso-Tethyan Ocean. • Early Jurassic gabbroic dikes were newly documented in the Amdo microcontinent, central Tibet. • Gabbroic rocks display different geochemical compositions with OIB and MORB features. • Zircon U-Pb dating on gabbroic rocks yielded nearly uniformed ages of 182–175 Ma. • Gabbroic rocks were formed by the lithospheric delamination after the Qiangtang-Amdo collision. [ABSTRACT FROM AUTHOR]

In this work, we report the geochemical, whole-rock Sr-, Nd-, and Hf-isotopes, and zircon U–Pb age and Hf–O isotopic compositions for six granitic intrusions in northeastern Fujian, coastal region of southeastern China, to elucidate the petrogenesis of aluminous and peralkaline A-type granites in this region. Zircon U–Pb dating of these rocks (including porphyritic syenites, porphyritic granites, alkali-feldspar granites, and arfvedsonite granites) yielded Late Cretaceous ages of 94–98 Ma. Mineral assemblage and geochemical features suggested that the arfvedsonite granites were peralkaline A-type but the porphyritic syenites, porphyritic granites, and alkali-feldspar granites were aluminous A-type. Geochemical data, whole-rock Nd–Hf isotopes (ε Nd (t) = −5.5 to −4.0, ε Hf (t) = −3.6 to 0), and the zircon Hf–O isotopes (ε Hf (t) = −3.0 to +1.4, δ18O = 5.4‰–6.0‰) indicated that the porphyritic syenites were produced by partial melting of crustal rocks in the lower crust. The porphyritic granites and alkali-feldspar granites had similar geochemical features and zircon Hf–O isotopic composition with the porphyritic syenites, suggesting that they were formed by feldspar-dominant crystal fractionation of deep crust derived syenitic magma under shallow crustal level. Compared with the aluminous A-type granites, the peralkaline A-type granites had lower abundance of Al 2 O 3 , MgO, CaO, Ba, and Sr, higher abundance of SiO 2 and HFSE, as well as higher ratio of total FeO/MgO, Ga/Al, and Rb/Sr. However, the whole-rock Nd-, Hf- and zircon Hf–O isotopic compositions of the peralkaline and aluminous A-type granites were similar. It could be inferred that the peralkaline A-type granites were formed by crystal fractionation of aluminous A-type granitic magmas. Since the studied A-type granitic intrusions were coeval with the bimodal volcanic rocks and the extensional basins in the coastal region of southeastern China, they were likely produced in an extensional setting, possibly during lithospheric thinning that resulted from the subduction of the paleo-Pacific plate beneath southeastern China. • Aluminous and peralkaline A-type granites were crystallized at 94–98 Ma. • Aluminous and peralkaline A-type granites were derived from a common source. • Aluminous A-type granite was produced by partial melting of lower crustal rocks. • Peralkaline A-type granite was formed via crystal fractionation. [ABSTRACT FROM AUTHOR]

Abstract Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600 °C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a <600 °C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic population during new rim growth. The younger, c. 1800 Ma U-Pb age is interpreted to date new apatite growth from a compositionally distinct reservoir driven by tectonothermal and fluid activity, consistent with regional mica Ar-Ar ages. Results from these two samples show that recrystallization, dissolution and regrowth processes likely formed the younger rim overgrowths, and at temperatures below those often considered to be closure temperatures for Pb diffusion in apatite. The results from these samples imply many apatite grains may not record simple thermally activated Pb diffusion profiles and cautions against inversion of apatite U-Pb data to thermal histories without detailed knowledge of the grain growth/alteration processes. Highlights • Present U-Pb apatite geochronology from the Akia Terrane Greenland • Apatites from the same sample may incorporate different common Pb. • Chemical and age zoning in apatite need not correlate • Dissolution and regrowth forming high U rims is prevalent. • Recrystallization may dominate over Pb diffusion in apatite. [ABSTRACT FROM AUTHOR]

This study provides new zircon U Pb geochronological and geochemical data for Late Jurassic to Early Cretaceous granitoids in the northern Great Xing'an Range (GXR), NE China, and uses these data to constrain the late Mesozoic tectonic evolution of the GXR. The zircons from these granitoids are magmatic, as indicated by their appearances during cathodoluminescence imaging and high Th/U ratios (0.21–2.35). Zircon U Pb dating indicates that the granitoids formed during the Late Jurassic (~161 Ma) and Early Cretaceous (~132 Ma). The Late Jurassic granitoids (LJG) are dominantly monzogranites with high SiO 2 and Na 2 O + K 2 O contents, and low MgO and FeO T contents. They are metaluminous, enriched in the light rare-earth elements (LREE) and the large-ion lithophile elements (LILE), depleted in the heavy REE (HREE) and high-field-strength elements (HFSE; e.g., Nb, Ta, Ti, and P), and have an adakitic affinity. The zircons from these monzogranites yield ε Hf (t) values of +5.7 to +8.2 and two-stage model ages (T DM2 ) of 749–618 Ma. These results indicate that the primary magma for the Late Jurassic granites was originated from partial melting of a thickened lower-crustal source. The Early Cretaceous granitoids are dominantly metaluminous to peraluminous porphyritic granites with higher HREE contents than the Late Jurassic monzogranites. They display negative Eu anomalies and have ε Hf (t) values of +3.1 to +9.0 with corresponding T DM2 ages of 877–553 Ma, suggesting they formed from magmas generated by partial melting of juvenile lower-crustal material. Combining these data with the geochemistry of coeval volcanic rocks within the GXR, we infer that the northern GXR records a late Mesozoic transition from compression to extension. The compression was most likely related to the Middle Jurassic closure of the Mongol–Okhotsk Ocean, whereas the extension was related to delamination of a thickened region of the lithosphere and/or subduction of the Paleo-Pacific Plate beneath Eurasia. [ABSTRACT FROM AUTHOR]

This paper reports zircon U–Pb geochronology, whole-rock chemistry and Sr–Nd–Hf isotopic data of intermediate-acid intrusive rocks from the Gerlache Strait area, Antarctic Peninsula. These intrusive rocks can be divided into three groups. Group #1 has an emplacement age of ca. 117 Ma, and is further subdivided according to K 2 O contents into High-K (HKS) and Low-K (LKS) Subgroups. The HKS monzogranites are weakly peraluminous, and yield ε Hf ( t ) and ε Nd ( t ) values of +0.9 to +2.3 and +0.1 to +2.3, respectively, with corresponding model Nd ages (T DM Nd ) of 766–471 Ma, indicating that they were derived from the partial melting of dominantly early Neoproterozoic to early Paleozoic juvenile basaltic materials with minor involvement of sediments. In contrast, the LKS granodioritic magma was derived from partial melting of early Paleozoic juvenile basaltic materials with ε Hf ( t ) and ε Nd ( t ) values of +10.3 to +12.5 and +5.4 to +5.5, respectively, and corresponding T DM Nd ages of 548–500 Ma. Group #2 consists of granite porphyry that formed at ca. 82 Ma and is characterized by positive values of ε Hf ( t ) (+5.1 to +8.1) and ε Nd ( t ) (+1.9 to +3.1) with weakly peraluminous chemistry and corresponding T DM Nd ages of 712–548 Ma, suggesting that it was generated from partial melting of dominantly Neoproterozoic juvenile basaltic materials with minor involvement of sediments. Group #3 comprises dioritic–granodioritic rocks that were emplaced at ca. 62–54 Ma. These rocks have Mg# values of 39–46, and ε Hf ( t ) and ε Nd ( t ) values of +6.7 to +12.2 and +3.6 to +7.2, respectively, with corresponding T DM Nd ages of 529–307 Ma, indicating that they were derived from partial melting of Paleozoic juvenile basaltic materials with minor injection of mantle materials. Spatially, the lithology of these plutons roughly changes from acid to intermediate from east to west, concomitant with increasing ε Hf ( t ) and ε Nd ( t ) values and decreasing initial 87 Sr/ 86 Sr ratios and T DM Nd ages. This trend reflects changes in source characteristics from a Gondwana affinity to a juvenile crust affinity. Overall, the southeast-to-northwest migration of magmatism in the northern Antarctic Peninsula since the Mesozoic may have been related to retreating subduction of the paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

Highly evolved Sn-polymetallic mineralization-related granites are intensively developed in the Nanling Range of South China. In this study, two types of granitic rocks (albite granite and greisenized granite) from the Laiziling pluton in the Xianghualing area were studied to elucidate magma evolution and the genesis of mineralization. The A-type Xianghualing granitic rocks are characterized by high SiO 2 (69.16–85.04%), Rb (759–2110 ppm), Ta (17.2–50.8 ppm), Nd (2.8–82.4 ppm) and 87 Sr/ 86 Sr (0.907275–4.181262) and low MgO (0.01–0.98%), TiO 2 (0.01–0.03%), Sr (1.4–70.2 ppm), Ba (1.4–132.5 ppm), Eu (0.03–0.21 ppm) and 143 Nd/ 144 Nd (0.512283–0.512326). The whole-rock εNd(t) values range from −6.3 to −6.0, with T 2DM ages of 1426–1454 Ma. The zircon εHf(t) values mostly range from −10 to −5, with dominant T DM C values of 1400–1800 Ma. This suggests that the Xianghualing granitic rocks were derived from partial melting of Mesoproterozoic basement rocks in the Cathaysian Block, in a lithospheric extension setting. Zircon U–Pb dating yielded five age clusters: Proterozoic (>900 Ma, n  = 9), Silurian (~430 Ma, n  = 4), Triassic (~220 Ma, n  = 16), Jurassic (~150 Ma, n  = 62) and Cretaceous (~80 Ma, n  = 28). Zircon internal textures, trace element contents and Hf isotopic compositions indicate that they formed from a range of sources including residual zircons from the magma source region, detrital zircons from local sediments, zircons captured from pre-existing magmatic rocks with obvious mantle signatures, magmatic and fluid-altered zircons, and late stage hydrothermal zircons. This suggests significant fractional crystallization, weak wall-rock assimilation/contamination and intense fluid differentiation/metasomatism during the genesis of the Xianghualing granitic rocks. M-type REE tetrad effects are seen not only in bulk rock compositions, but also in individual zircon grains, indicating that highly fractionated and reduced F-rich fluids played an important role in the formation of Sn-polymetallic mineralization. Guided by the major Mesozoic W–Sn ore-forming events occurring in the Cathaysian Block of South China, a multi-stage genetic model is proposed for the Xianghualing granitic-minerogenic system: initial enrichment of W–Sn in the Triassic (~220 Ma), dominant Sn-polymetallic metal precipitation in the Jurassic (~150 Ma), and superimposed mineralization in the Cretaceous (~80 Ma). [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) evolved through a long-lived orogeny involving multiple episodes of subduction and accretion marking a major phase of continental growth during the Paleozoic. The northern part of the Western Junggar region (NW Junggar) offers a window into these processes, particularly to constrain the timing of closure of the Paleo-Asian Ocean. Here we report geochemical, geochronological, and isotopic data from K-feldspar granites and adakitic rocks from the NW Junggar region. Zircon U-Pb ages suggest that the granites were emplaced during Early Silurian to the Early Carboniferous (434–328 Ma). The granites show geochemical characteristics similar to those of A-type granites, with high SiO 2 (71.13–76.72 wt%), Na 2 O + K 2 O (8.00–9.59 wt%), and Al 2 O 3 (12.28–14.08 wt%), but depleted Sr, Nb, Ta and Eu. They display moderate to high positive εNd(t) and εHf(t) values (4.26–8.21 and 7.69–14.60, respectively) and young Nd and Hf model ages (T 2DM-Nd = 489–740 Ma and T 2DM-Hf = 471–845 Ma), suggesting magma derivation through partial melting of lower crust in the Boshchekul-Chingiz and Zharma-Saur arcs. The adakites are characterized by high Sr content (406.5–751.6 ppm), and low Y (13.8–16.4 ppm) and Yb (1.5–1.8 ppm) content, yielding relatively high Sr/Y ratios (25.38–49.41) similar to those of modern adakites. They have high positive εNd(t) and εHf(t) values (7.85–8.25 and 13.23–15.97, respectively) and young Nd and Hf model ages (T 2DM-Nd = 429–535 Ma and T 2DM-Hf = 355–550 Ma), indicating that their source magmas were likely derived from partial melting of the oceanic crust beneath the Boshchekul-Chingiz arc. The petrogenesis and distribution of the A-type granites and adakites, as well as the tectonic architecture of the region, suggest that a ridge subduction event might have occurred during the Early Silurian to Early Carboniferous. In combination with previous studies in the Chinese Altai, we suggest a two-sided ridge subduction model for the Junggar-Altai region. [ABSTRACT FROM AUTHOR]

Adakitic intrusions are supposed to have a close genetic and spatial relationship to porphyry Cu deposits. However, the genesis of adakitic intrusions is still under dispute. Here, we describe newly discovered intrusive complex rocks, which are composed of ore-bearing, layered magnetite-bearing gabbroic and adakitic rocks in Jiamate, East Junggar, NW China. These Jiamate Complex intrusions have diagnostic petrologic, geochronologic and geochemical signatures that indicate they were all generated from the same oxidized precursor magma source. Additionally, these layered rocks underwent the same fractional crystallization process as the ore-bearing adakitic rocks in the adjacent Kalaxiangar Porphyry Cu Belt (KPCB) in an oceanic island arc (OIA) setting. The rocks studied for this paper include layered magnetite-bearing gabbroic intrusive rocks that contain: (1) gradual contact changes between lithological units of mafic and intermediate rocks, (2) geochemical signatures that are the same as those found in oceanic island arc (OIA) rocks, (3) typical adakitic geochemistry, and (4) similar characteristics and apparent fractional crystallization relationships of ultra-basic to basic rocks to those in the nearby Beitashan Formation and to ore-bearing adakitic rocks in the KPCB. They also display similar zircon U-Pb and zircon Hf model ages. The Jiamate Complex intrusions contain intergrowths of magnetite and layered gabbro, and the intermediate-acidic intrusions of the Complex display typical adakitic affinities. Moreover, in conjunction with previously published geochronological and geochemistry data of the mafic rocks in the Beitashan Formation and in the KPCB area, additional data generated for the Jiamate Complex intrusions rocks indicate that they were formed from fractional crystallization processes. The Jiamate Complex intrusions most likely were derived from a metasomatized mantle wedge that was underplated at the root of the Saur oceanic island arc (Saur OIA). The ore-bearing adakitic intrusions in the KPCB and the adakitic Jiamate Complex intrusions were both probably generated from the same basaltic parental magmas through fractional crystallization. In addition, characteristics of the layered, magnetite-bearing, oxidized, basaltic Jiamate Complex intrusive rocks indicate that they are likely to be the parental arc magmas for the nearby porphyry Cu deposits. This conclusion is based on new interpretations of the regional and local geology, on interpretation of new geochemical analysis, new stable isotope analysis, new geothermobarometry, and new zircon age dating as well as other techniques and interpretations. [ABSTRACT FROM AUTHOR]

The Xiaoyao tungsten polymetallic skarn deposit in the eastern Jiangnan Massif of Yangtze Block is located at the contact between a granodiorite pluton and Sinian–Cambrian limestone. The intrusions in the tungsten-rich district comprise the Xiaoyao and other granodiorite plutons and granite porphyry dikes. The age determinations by LA–ICP–MS U–Pb dating of zircons indicate that the granodiorite formed at 149.4 ± 1.1 Ma, whereas the granite porphyry was emplaced at 133.2 ± 0.7 Ma. Re–Os dating of molybdenite from the skarn orebodies yielded a weighted average age of 148.7 ± 2.3 Ma (n = 5). These ages indicate that the tungsten mineralization is temporally related to the granodiorite. The granodiorites are metaluminous (A/CNK = 0.86–0.98) and in the high-K calc-alkaline series. They contain hornblende and have a negative correlation between P 2 O 5 and SiO 2 , indicating that they are typical I-type intrusions. The granite porphyries exhibit high alkali contents (Na 2 O + K 2 O = 7.97–9.53%), elevated FeO T /(FeO T + MgO) ratios (0.83–0.94), high concentrations of Zr, Nb, Ce, and Y, and high Zr saturation temperatures (average of 812 °C); thus, they are geochemically similar to A-type intrusions. The initial 87 Sr/ 86 Sr and ε Nd (t) values range respectively from 0.7074 to 0.7083 and from − 7.9 to − 1.3 for the granodiorite, and from 0.7008 to 0.7083 and from − 6.3 to − 4.7 for the granite porphyry. In addition, two-stage Nd model ages (T 2DM ) of 1.0–1.6 Ga for the granodiorite and 1.3–1.4 Ga for the granite porphyry indicate that the Proterozoic crustal rocks of the Shangxi Group could have contributed to the Xiaoyao magmas. The rhenium contents of the molybdenite grains vary from 32 to 136 ppm, suggesting that the molybdenum was derived mainly from a mixture of mantle and crustal sources. Based on the new geochemical data and regional geological investigations, we propose that the Late Jurassic mineralization-related I-type granodiorite was derived from the Neoproterozoic Shangxi metamorphic rocks with some additional input of mantle material. The magmatism was triggered by asthenospheric upwelling induced by slab tearing during oblique subduction of the paleo-Pacific plate beneath the South China Block. [ABSTRACT FROM AUTHOR]

This study deals with arc-type and subsequent bimodal volcanic rocks interbedded with (late) Cretaceous sedimentary formations near Gaize, central Tibet that shed new light on the Tethyan evolution along the Bangong-Nujiang suture. Unit I consists of trachyandesites interbedded with fine-grained sandstone, slate, and limestone. Zircon dating on a trachyandesite sample yields a 206 Pb/ 238 U age of 99 ± 1 Ma. The trachyandesites are characterized by strong enrichment in LILE but depletion in HFSE, low zircon saturation temperatures (T Zr = 642–727 °C), and high oxygen fugacity (∆ FMQ = − 0.67–0.73), indicating their arc affinities. Unit II comprises a bimodal basalt-rhyolite suite interbedded with coarse-grained sandstone and conglomerate. Zircon dating on two rhyolitic samples yield 206 Pb/ 238 U ages of 97.1–87.0 Ma. In contrast with Unit I trachyandesites, Unit II basalts and rhyolites exhibit OIB-like trace element patterns, high temperatures ( T = 1298–1379 °C for basalts, T Zr = 855–930 °C for rhyolites), and low oxygen fugacity (∆ FMQ = − 3.37 ~ − 0.43), suggesting that Unit II bimodal volcanic rocks probably formed in an extensional setting. The Sr-Nd isotopes of both Unit I ( 87 Sr/ 86 Sr i = 0.7052–0.7074, εNd(t) = − 2.21–1.02) and Unit II ( 87 Sr/ 86 Sr i = 0.7057–0.7098, εNd(t) = − 3.22–0.88) rocks are similar to mantle-wedge-derived volcanic rocks within the southern Qiangtang block. The parental magma of Unit I trachyandesites was formed by fluid induced melting of the mantle wedge above the subducted Bangong-Nujiang Tethyan slab, and contaminated by crustal materials during MASH process within a deep crustal hot zone; and Unit II bimodal volcanic rocks were derived by melting of upwelling asthenosphere and a mildly metasomatized mantle wedge during the Lhasa-Qiangtang collision. We propose that the transition from the Bangong-Nujiang Tethyan subduction to the Lhasa-Qiangtang collision occurred during the Late Cretaceous in central Tibet. [ABSTRACT FROM AUTHOR]

Syn-exhumation and post-collisional mafic magmatic rocks are generally exposed in continental collision orogens. Their geochemical compositions can not only reflect the nature of orogenic lithospheric mantle but also provide a window to trace crust-mantle interaction in continental collision zones. Herein, we present a combined study of whole-rock major-trace elements and Sr-Nd-Hf isotopes as well as zircon U Pb ages and Hf O isotopes for the Paleozoic mafic magmatic rocks from the North Qaidam orogen, northeastern Tibet. Zircon U Pb dating for the rocks yields two groups of ages of 420 ± 8 to 395 ± 2 Ma and 383 ± 5 to 368 ± 3 Ma, corresponding to the syn -exhumation and post-collisional stages, respectively. These mafic magmatic rocks are characterized by arc-like trace element distribution patterns, enriched to depleted radiogenic Sr-Nd-Hf isotope compositions and high zircon δ18O values, which are comparable to those of the orthogneiss and continental eclogite in this orogen. This indicates their derivation from the orogenic lithospheric mantle modified by the subducted continental crust during the continental collision. Significant differences in radiogenic isotope compositions between the syn -exhumation and post-collisional mafic magmatic rocks suggest their mantle sources were mainly metasomatized by the orthogneiss- and continental eclogite-derived melts, respectively. Quantitative modelling of trace element compositions shows that about 93.0:6.0:1.0 and 91.7:2.8:5.5 mixture of the mantle peridotite, orthogneiss- and continental eclogite-derived melts with 23% and 28% aggregated fractional melting can closely match the syn -exhumation and post-collisional mafic magmatic rocks, respectively. The reaction of the continental crust-derived melts with mantle peridotite would result in the heterogeneous orogenic lithospheric mantle. Therefore, the syn -exhumation and post-collisional mafic magmatic rocks provide a snapshot of the compositional variations in the orogenic lithospheric mantle and the crust-mantle interaction in the continental collision zone. • Syn-exhumation/post-collisional mafic magmatic rocks in the North Qiadam orogen. • They were derived from a heterogeneous orogenic lithospheric mantle. • The mantle source was metasomatized by melts from the subducted continental crust. • These rocks record crust-mantle interaction in the continental subduction channel. [ABSTRACT FROM AUTHOR]

The Paleo-Tethyan arc belt is host to a small number of porphyry Cu deposits the key controls on which remains poorly understood. It has been hypothesized that the Paleo-Tethyan arc magmas were reduced and therefore less fertile for porphyry Cu formation but few studies have been conducted to directly assess the magmatic oxygen fugacity. We investigate the magma fertility of eastern Paleo-Tethyan arc igneous rocks in the Sanjiang region, SW China, represented by the Maoding (268.3 ± 2.3 Ma), Suwalong (275.6 ± 1.4 Ma to 264.7 ± 1.4 Ma) and Baimaxueshan (255.7 ± 1.5 Ma to 249.3 ± 1.1 Ma) granitoids. They have geochemical features consistent with typical continental arc rocks, formed from partial melting of the mantle wedge, with increasing contamination of crust-derived melts over time. The presence of amphibole, high Sr/Y ratios (35 ± 20, n = 17), and lack of negative Eu anomalies (Eu N /Eu N ⁎ = 1.04 ± 0.3, n = 17) are consistent with derivation from hydrous magmas. Zircons from the intrusive rocks have relatively low Eu N /Eu N ⁎ (mostly <0.4) ratios and calculated ΔFMQ values (−2.1 ± 1.2, n = 86). Combined with apatite microphenocrysts with extremely low sulfur contents (< 0.12 wt% SO 3), it suggests that the intrusions originated from water-rich but reduced arc magmas, that were less fertile for porphyry Cu formation. Our study highlights that magmatic f O 2 is probably a critical control on the prospectivity of arc systems and confirms that zircon and apatite compositions can be used to evaluate porphyry Cu fertility. • The Paleo-Tethyan arc igneous rocks were dated from ~275 to 249 Ma. • They were derived from partial melting of mantle wedge during MASH processes. • These arc magmas were reduced and less fertile for porphyry Cu formation. • Zircon and apatite compositions can be used to evaluate porphyry Cu fertility. [ABSTRACT FROM AUTHOR]

The study of volcanism near unstable plate triple junctions (TJs) offers a unique opportunity to investigate the interactions between mantle dynamics and lithospheric deformation in relation to short-term plate reconfiguration. From combined geochronological and geochemical analyses on Terceira, S. Jorge and Faial volcanic islands, we evidence contrasted modes of melt generation near the Azores Triple Junction during the last 1.3 Myr. The oldest lavas (> 800 ka) erupted along N150 elongated volcanic systems in S. Jorge and Faial have homogeneous isotopic compositions which partly overlap the compositional field of MORBs from the adjacent Mid-Atlantic Ridge (MAR). In contrast, the younger lavas (< 750 ka) erupted along the N110 main structural direction on the three islands are significantly more enriched in LILE and LREE, and have more variable and generally more radiogenic Sr, Pb, Nd and Hf isotopic ratios. Altogether, our data do not support the presence of an active mantle plume under the central Azores. Instead, they suggest that magma generation results from decompression melting of a heterogeneously fertilized mantle (fossil plume?). The higher geochemical heterogeneity of the lavas erupted during the last 750 kyr likely reflects low-degree partial melting promoted by recent reactivation of pre-existing MAR Fracture Zones. We propose that the sub-aerial volcanism over the last 1.3 Myr in the central Azores records a sudden change in the conditions of melt generation, due to a major reconfiguration in regional deformation associated with the recent reorganization of the Eurasia–Nubia plate boundary. [ABSTRACT FROM AUTHOR]

Ferroan granitoids are typically generated in the extensional tectonic settings, and thus record important geodynamic processes related to crustal and mantle evolution. However, their petrogenesis remains controversial. In this study, we investigated newly identified ferroan granites in the Lake Cona region of the southern Qiangtang subterrane (SQT), central Tibet. We present zircon U–Pb age and Hf–O isotope, whole-rock major and trace element and Sr–Nd isotope, and mineral major element data for these rocks. The Lake Cona granites consist of biotite monzogranite and granite porphyry. Zircon U–Pb dating indicates these rocks were generated in the late Late Cretaceous (ca. 75 Ma). The biotite monzogranites are metaluminous to weakly peraluminous, and characterized by relatively high SiO 2 (67.1–68.6 wt%), total alkali (10.4–10.8 wt%), Th (31–46 ppm), light rare earth element (LREE), and Zr + Nb + Ce + Y (421–730 ppm) contents, and high Fe-numbers (0.83–0.91; FeOt/[FeOt + MgO]). These rocks can be classified as alkalic ferroan granites. However, compared with the typical ferroan granitoids generated under relatively anhydrous conditions, the biotite monzogranites have higher Al 2 O 3 (15.9–17.0 wt%) contents, lower 10000 × Ga/Al (2.1–2.5) ratios, and small negative Eu anomalies, suggesting that they were generated by brine-assisted (a fluid with low water activity) crustal anatexis. The biotite monzogranites have (87Sr/86Sr) i = 0.7065–0.7069, ε Nd (t) = −2.3 to −1.9, δ18O = 6.0–6.6‰, and ε Hf (t) = +2.1 to +9.3, indicative of a magma source that was a mixture of juvenile and ancient crustal components. The granite porphyries also have high contents of total alkalis (9.9–10.2 wt%) and Fe-numbers (0.87–0.90), and similar Sr–Nd–Hf–O isotopic compositions as the biotite monzogranites, but have higher SiO 2 and lower TiO 2 , MgO, TFe 2 O 3 , P 2 O 5 , CaO, and REE contents, and larger negative Eu anomalies. These features suggest that the granite porphyries represent the highly evolved biotite monzogranitic magmas that underwent differentiation in the shallow crust. The Lake Cona ferroan granites formed in a post-collisional extensional setting that had additional heat input from the deep mantle. Unlike the early Late Cretaceous that was dominated by calc-alkaline magmatism in the SQT, the occurrence of alkali ferroan granites in the late Late Cretaceous may record the transformation from a post-collisional to an intraplate tectonic regime in the central Tibet. • The Lake Cona alkali ferroan granites formed at ca.75 Ma. • Ferroan granites generated by brine-assisted anatexis. • A Campanian transition from a post-collisional to intraplate setting [ABSTRACT FROM AUTHOR]

Abstract: Systematic 40Ar/39Ar dating of granitoids and surrounding metamorphic rocks has been performed in the Limousin area (W of French Massif Central) in order to provide new constrains concerning its late-orogenic thermal and tectonic evolution. The same 40Ar/39Ar age of ca. 335–338Ma is found on the present-day outcrop surface for most of the Limousin metamorphic rocks, hence indicating that the entire massif was uniformly cooled down at this period. These ages are very close to the 40Ar/39Ar ages proposed in the Sioule and Brevenne areas in the literature, but also to the coupled tectonic and magmatic activity in the south Limousin. These results help to document the existence of two exhumation stages, each one associated with an extensional stage. A first exhumation stage, has been active at ca. 335–340Ma. Available data indicate that this extension and associated exhumation and cooling occurred over a distance of more than 200km in the internal zones of the belt, whereas compression was still active in the northern and southern parts of the belt. A second exhumation stage may be related to the late-orogenic extension and collapse of the belt, at ca. 310–305Ma, and is characterized by the uplift of the St. Sylvestre complex by unroofing of the overlying metamorphic and granitoidic formations. [Copyright &y& Elsevier]

Abstract: The U–Th–Pb system of monazite behaves differently dependent on the deformation mechanism – dissolution precipitation creep (DPC) or dislocation creep – activated in the hosting metamorphic rocks. This can be exploited to use monazite for dating deformation, as is shown in rocks subsequently deformed by dislocation creep and DPC. In rock layers intensely deformed by DPC, mineral reactions, particularly the dissolution of feldspar and apatite increased the alkali-content and reactivity of the fluid. This in turn led to dissolution of old predeformative monazite grains. New synmetamorphic monazite grains formed as the result of inter-grain transport of material over distances within the grain-scale. This process efficiently led to complete resetting of the monazite U–Th–Pb system, even at temperatures prevailing during greenschist facies conditions. The chemical composition of the new monazite records the dissolution of the old feldspar by a less pronounced negative Eu anomaly compared to old monazite. The shape of the monazite grains that precipitated during creep indicates the sense of shear in the shear zone, thus linking the obtained ages directly to the map-scale tectonic transport. In rock layers predominantly deformed by dislocation creep, old monazite grains survived intense mylonitization and high strain, and show a core–rim structure. The cores are patchy, reflecting intra-grain, coupled dissolution–reprecipitation replacement processes. A wide range in apparent, geologically inaccurate Th/Pb and U/Pb ages among the patchy zones is the result of incomplete removal of in-situ grown radiogenic Pb from the patchy domains, depletion of Th and U and the redistribution of Th and U among the domains. Exclusively in the rims of the old monazite, the chemical composition correlates to that of the syndeformative monazites, and the U–Th–Pb system reflects the subsequent DPC. Accordingly, rocks pervasively deformed by DPC should be preferably used to obtain monazite most suitable for precise dating of creep episodes linked to shear deformation and for determination of deformation rates. [Copyright &y& Elsevier]

Abstract: The Tianyu mafic–ultramafic intrusion is one of many important sulfide-bearing mafic–ultramafic intrusions in the eastern Tianshan terrane located in the southern margin of the Central Asian Orogenic Belt in north Xinjiang, NW China. The origin of sulfide mineralization in these intrusions, their relationship with Permian basalts and A-type granites, and the geodynamic setting of the bimodal magmatism in the region are controversial. In this paper we use zircon U–Pb age, Hf–Sr–Nd–Os isotope and lithophile–chalcophile trace element constraints from the Tianyu mafic–ultramafic intrusion to address these important issues. The U–Pb age of zircon from the Tianyu intrusion determined by SIMS is 280±2Ma. This confirms that the Tianyu intrusion is coeval with most sulfide-bearing mafic–ultramafic intrusions and some basalts and A-type granites in the Tianshan region. Similar to coeval basalts in the nearby Tuha basin, the Tianyu intrusive rocks are characterized by negative Nb anomaly and elevated εNd values varying between −1 and +4.6. The negative Nb anomaly in the Tianyu intrusion is not as pronounced as in the coeval A-type granites but the εNd values for these bimodal rocks are similar. The εHf values of zircon from the Tianyu intrusion are positive, varying between 3 and 8. These values suggest that the parental magma of the Tianyu intrusion was dominated by melt derived from a depleted source mantle. The γOs values of pyrrhotite from the Tianyu intrusion are high, ranging from 725 to 995, which can be modeled by selective assimilation of sulfide from the lower and upper crusts. Negative Pt anomaly is present in relatively sulfide-rich samples such as semi-massive and massive sulfide ores but not in sulfide-poor samples, which is more consistent with the effect of post-magmatic hydrothermal alteration than the original signature of the parental magma. The results of modeling using the compositions of selected disseminated sulfide samples suggest that the parental magma of the Tianyu intrusion was depleted in all PGE, which is consistent with previous sulfide segregation at depth. Our data and modeling results support the model of decompression melting of upwelling asthenosphere due to slab break-off during a transition from oceanic subduction to arc–arc or arc–continent collision in the Permian. Decompression melting of the upwelling asthenosphere in the region produced mafic magma. Partial melting in the lower parts of a juvenile arc crust due to mafic magma underplating produced granitic melts. Mixing of the mafic magma with a small amount of granitic melts at depth followed by contamination with the upper crust at a higher level formed the parental magma of the Tianyu intrusion. PGE depletion in the parental magma of the Tianyu intrusion can be attributed to sulfide segregation associated to the first stage of crustal contamination at depth. We suggest that the formation of sulfide ores in the intrusion was related to the second stage of crustal contamination in the upper crust. [Copyright &y& Elsevier]

Abstract: Kimberlite, a deep-sourced ultramafic potassic rock, carries not only diamond, but also invaluable mantle xenoliths and/or xenocrysts, which are important for tracking the evolution of subcontinental lithospheric mantle (SCLM). However, it is challenging to accurately determine the emplacement age of kimberlite and its compositions of primary magma because of modifications by crustal and/or mantle contamination and post-emplacement alteration. This paper reports emplacement ages of diamondiferous kimberlites in Mengyin and Fuxian of the North China Craton (NCC) using three different dating methods. For Mengyin kimberlite, single-grain phlogopite Rb–Sr dating yields an isochron age of 485±4Ma, U–Th–Pb analyses on perovskite give a 238U–206Pb age of 480.6±2.9Ma and a 232Th–208Pb age of 478.9±3.9Ma, and baddeleyite yields a 207Pb–206Pb age of 480.4±3.9Ma. For Fuxian kimberlite, baddeleyite gives a 207Pb–206Pb age of 479.6±3.9Ma, indicating that the Paleozoic kimberlites in the NCC were emplaced at ~480Ma. Numerous lines of evidence indicate that the studied baddeleyites are xenocrysts from the SCLM, and can be used to constrain Hf isotope compositions (ε Hf(t)~−6) of the SCLM when kimberlite erupted. Combined with data from Mesozoic–Cenozoic mantle-derived rocks and xenoliths, the Hf isotope evolution trend of the SCLM beneath NCC before craton destruction was tentatively constructed, which suggested that the Archean SLCM was enriched by metasomatism at ~1.3Ga. Further Hf isotope investigations on additional SCLM-derived materials could be used to compare with the constructed Hf isotope evolution trend before craton destruction to determine when lithospheric thinning occurred. [Copyright &y& Elsevier]

Abstract: The studied ultrahigh-pressure (UHP) eclogites, located in the southwestern part of the North Dabie complex zone (NDZ) in central China, represent deeply subducted mafic lower continental crust of the South China Block and display a multiple metamorphic evolution. However, the exact timing of the UHP metamorphism in the NDZ is poorly constrained, and thus impedes our understanding of the tectonic evolution of this area. In order to constrain the ages of peak UHP metamorphism and subsequent retrogression during continental subduction and exhumation, zircon from the eclogites in the NDZ has been investigated by a combined petrological, trace element and U–Pb isotopic study. In combination with petrological data, the present zircon SHRIMP and LA-ICPMS U–Pb dating provides precise constraints on the timing of multistage metamorphic events on the eclogites in the region. The U–Pb isotope in zircon from the eclogites records the times of multiple discrete events in the history of the rock such as Neoproterozoic, 238±2Ma, 222±4–227±2Ma, 210±4–215±2Ma, 199±2Ma and 176±2–188±2Ma. Neoproterozoic ages defined by relic igneous cores represent their protolith time and the other age-groups reflect their metamorphic records by CL images, low Th/U ratios and mineral inclusions. By U–Pb age, trace element and mineral inclusion of zircon, at least two episodes of eclogite-facies metamorphism have been identified from the eclogites, best estimated at 226±3 and 214±3Ma, respectively. The younger ages of 199±2 and 176–188Ma most likely record the granulite-facies overprinting and amphibolite-facies retrogression occurring during exhumation whereas the age of 238±2Ma probably reflects the prograde metamorphic timing prior to the UHP metamorphism. Thus, Neoproterozoic mafic lower continental crust was subducted to depths greater than 120km (corresponding to the lowest pressure for diamond formation) and suffered from UHP metamorphism at 226±3Ma. Then these UHP metamorphic rocks were exhumed to about 60km depth at 214±3Ma and experienced high-pressure quartz eclogite-facies retrograde metamorphism, and subsequently to lower- and upper-crustal levels and overprinted by granulite- and amphibolite-facies metamorphism, respectively. [Copyright &y& Elsevier]

Abstract: The geological evolution in the southwestern Chinese Tianshan orogen in NW China is poorly understood because of controversial geochronological results of the low-temperature eclogites. It is likely due to Sm–Nd and Rb–Sr isotopic disequilibrium in different mineral fractions, excess 40Ar in the high-pressure K-bearing minerals, and multi-stage growths of zircon in U–Pb system. Rutile, as a typical eclogite-facies mineral with high U/Pb ratio, is a feasible candidate to constrain the eclogite-facies metamorphic event. In this study, we measured U–Pb rutile age data using SIMS (Cameca IMS 1280) for low-temperature eclogites from southwestern Chinese Tianshan orogen, NW China. We demonstrate that SIMS is a powerful technique for in-situ U–Pb dating of rutile with U content as low as 1ppm. SIMS U–Pb rutile dating yielded an age of 318±7Ma, which may record the time when the rocks cooled down to the closure temperature of Pb in rutile (ca. 500°C), but should be very close to the time of eclogite-facies metamorphism in terms of common fast exhumation of coesite-bearing eclogite. This new proof strongly suggests a late Carboniferous collision between Kazakhstan–Yili block and Central Tianshan microcontinent. [ABSTRACT FROM AUTHOR]

Abstract: The Kokchetav Massif of northern Kazakhstan is the best-known metamorphic diamond locality among numerous ultrahigh-pressure (UHP) terranes in the world. At the Kumdy-Kol deposit, diamondiferous rocks are interbedded with granitic gneisses, and biotite gneisses; some have been migmatized. Some granite gneisses and migmatites were formed by partial melting of diamondiferous rocks. To verify such suggestion, sensitive high resolution ion microprobe (SHRIMP) U–Pb dating of zoned zircons from migmatites at the Kumdy-Kol region was performed to constrain the age of partial melting of the Kokchetav UHP metamorphic rocks. Most age data from core and rim domains of zircon separates are concordant. The apparent 206Pb/238U ages for core and rim domains of zirconsare nearly identical within analytical error. All SHRIMP analyses of zircons from four samples fall in the range 508–538 Ma with the weighted mean age for all zircon domains at 526±2.1 (MSWD=1.7). Our data show that migmatization of UHP pelites occurred later than the peak metamorphism (537±9 Ma) and the decompression partial melting took place during exhumation of diamondiferous rocks from mantle depths to amphibolite-facies conditions at mid-crustal levels (507±8 Ma). [Copyright &y& Elsevier]

The Kuching zone, the most important tectonic boundary in Borneo, separates the Sibu zone in Central Sarawak from the Schwaner Mountains granitoids in SW Borneo. It potentially provides a key window for probing the paleo-Pacific subduction process. This paper presents new geochronological, elemental and Sr Nd isotopic data for the Pakong-Serabang and Serian mafic rocks, along with detrital zircon U Pb age-data for the associated greywacke in the Sarawak Kuching zone. These mafic rocks are dated at ~77–98 Ma and show distinctive geochemical signatures. The Pakong- Serabang mafic rocks are subalkaline basalt with SiO 2 = 46.22–51.75 wt%, TiO 2 = 0.49–2.42 wt% and MgO = 6.30–10.54 wt%. They exhibit MORB-like PM-normalized patterns with depletion in LILEs and HFSEs. Their 87Sr/86Sr(t) and ε Nd (t) range from 0.70285 to 0.70728 and + 7.4 to +9.4, respectively, originating from a slab-derived fluid-modified MORB-like source. The late Cretaceous Serian Volcanics are marked by SiO 2 of 51.52–57.90 wt%, MgO of 3.50–5.06 wt% with mg-number = 36–46 and show arc-like geochemical signatures with (Nb/La) n = 0.37–0.47. They have 87Sr/86Sr(t) = 0.71188–0.71417 and ε Nd (t) = −11.1 ~ −7.3, and were derived from a mantle wedge with the input of recycled sedimentary components. The detrital zircon grains from the associated sandstones give similar age-spectra to those in East Peninsular Malaysia and SE Vietnam. Our data revealed a Cretaceous Kuching trench-arc system. In combination with other geological observations, it is concluded that NW Borneo to the southwest of the Sarawak Kuching zone was a part of the Indochina/East Peninsular Malaysia fragment in SE Asia prior to the Jurassic and re-activated as an active continental margin in the Cretaceous. Widespread accretionary orogenesis along the Kuching zone likely initiated at or before the early Cretaceous and ended no earlier than the latest Cretaceous in response to the westward subduction of the paleo-Pacific slab. • The mafic rocks in the Kuching zone of Sarawak Malaysia were dated at 77–98 Ma. • The Pakong-Serabang basalts originated from the slab fluid-modified MORB-like source. • The Serian Volcanics were derived from the recycled sediment-modified wedge source. • The Kuching Cretaceous accretionary orogenesis results from paleo-Pacific subduction. [ABSTRACT FROM AUTHOR]

Abstract: Re–Os dating of molybdenite from small deposits is used to define crustal domains exhibiting ductile versus brittle behaviour during gravitational collapse of the Sveconorwegian orogen in SW Scandinavia. A 1019±3 Ma planar quartz vein defines a minimum age for brittle behaviour in central Telemark. In Rogaland–Vest Agder, molybdenite associated with deformed quartz and pegmatite veins formed between 982±3 and 947±3 Ma in the amphibolite-facies domain (three deposits) and between 953±3 and 931±3 Ma west of the clinopyroxene-in isograd (two deposits) in the vicinity of the 0.93–0.92 Ga Rogaland anorthosite complex. The data constrain the last increment of ductile deformation to be younger than 0.95 and 0.93 Ga in these two metamorphic zones, respectively. Molybdenite is the product of an equilibrium between biotite, oxide and sulfide minerals and a fluid or hydrated melt phase, after the peak of 1.03–0.97 Ga regional metamorphism. Molybdenite precipitation is locally episodic. A model for gravitational collapse of the Sveconorwegian orogen controlled by lithospheric extension after 0.97 Ga is proposed. In the west of the orogen, the Rogaland–Vest Agder sector is interpreted as a large shallow gneiss dome, formed slowly in two stages in a warm and structurally weak crust. The first stage at 0.96–0.93 Ga was associated with intrusion of the post-collisional hornblende–biotite granite suite. The second stage at 0.93–0.92 Ga, restricted to the southwesternmost area, was associated with intrusion of the anorthosite–mangerite–charnockite suite. Most of the central part of the orogen was already situated in the brittle upper crust well before 0.97 Ga, and did not undergo significant exhumation during collapse. In the east of the orogen, situated against the colder cratonic foreland, exhumation of high-grade rocks of the Eastern Segment occurred between 0.97 and 0.95 Ga, and included preservation of high-pressure rocks but no plutonism. [Copyright &y& Elsevier]

The early to middle Paleozoic accretionary history of the Chinese Altai orogen remains controversial, especially along its southern margin facing the Paleo-Asian Ocean. This study conducts a systematic investigation on the Devonian meta-volcanic sequences from the Altay Formation in the southern Chinese Altai to constrain their petrogenesis and tectonic implications. LA-ICP-MS zircon U Pb dating for rocks from the bottom and top layers of the studied volcanic sequences indicates their eruption age at ca. 380 Ma. The basaltic rocks are low-K tholeiitic with high TiO 2 (average = 1.98 wt%), and have rare-earth element (REE) patterns similar to the mid-ocean ridge basalt (MORB), in spite of a large variation in light REE (LREE). They also show enrichment in large ion lithophile elements (LILE; e.g. Ba, U, and Th) and depletion in high field strength elements (HFSE; e.g. Nb and Ta), which are hallmarks of supra-subduction zone basaltic magma. Thus, the elemental data indicate that these rocks are compositionally intermediate between MORB and island-arc tholeiite (IAT). The basaltic samples have positive εNd(t) values (+3.1 to +10.3) and elevated initial 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb isotopic ratios. Whole-rock elemental and isotopic data suggest that the rocks were likely derived from a dominant N-MORB type depleted asthenosphere mantle, which was variably metasomatized by or interacted with the relatively enriched sub-arc mantle. In combination with the field relationship and regional geology, our study suggests that the meta-basaltic rocks from the middle Altay Formation formed in a mature back-arc spreading environment. We propose an evolving tectonic scenario from a magmatic arc to arc rifting, and finally back-arc opening in the southern Chinese Altai, which corresponds to an extensional regime and resultant asthenosphere upwelling event in this region during Devonian time, probably in response to a trench retreat. • Studied meta-basalts from the Altai Formation erupted between 385 and 376 Ma. • The Chinses Altai experienced arc-rifting and back-arc spreading in the Devonian. • Upwelling of the asthenosphere prevailed in response to a possible slab rollback. [ABSTRACT FROM AUTHOR]

Identifying basement rocks is critical to understanding the continent formation and evolution during orogenesis. Despite two decades of research, the age and composition of the basement rocks of the Southern Qiangtang Terrane/Microcontinent (SQT), Central Tibet are still unclear. In this study, zircon U–Pb ages and Hf–O isotopes, as well as whole-rock Nd isotopes are presented for the oldest known igneous rocks in the SQT. Precise SIMS zircon U–Pb dating of these rocks reveals that these early Paleozoic granites were crystallized at ca. 480‐465 Ma. They exhibit a wide range of isotopic values, with unradiogenic whole rock ε Nd (t) and zircon ε Hf (t) values ranging between −8.3~−7.7 and −8.2~−2.3, respectively, and by high δ18O zircon values of +8.1~+11.4‰. These results reveal that the early Paleozoic granites were crystallized from magmas that were almost entirely sediment-derived. When viewed in concert with regional data and constraints on the tectonic evolution of northern Gondwana, the sources for the early Paleozoic granites are herein proposed to have been deposited in an extensional basin, implying that these early Paleozoic granites were generated in an extensional setting within an accretionary orogen. Thus, the early Paleozoic granites are considered to represent the basement of the SQT. After a long period of attachment to northern Gondwana, the SQT became a small microcontinent when it was rifted and detached from northern Gondwana during Early Permian. After this time, it drifted northwards to Asia, and collided with the Northern Qiangtang Terrane to form a unified Qiangtang terrane in the Late Triassic. Thus, the SQT records a complete Wilson cycle from construction, rifting and departure, drifting to collision. • Pure sedimentary-derived early Paleozoic granites reported in Southern Qiangtang. • The basement of the SQT formed during early Paleozoic. • The SQT recorded a whole Wilson cycle from construction, rifting to collision. [ABSTRACT FROM AUTHOR]