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Neoproterozoic magmatism associated with the assembly and configuration of the Rodinia supercontinent is widely distributed in the India-Himalayan terrane. However, its petrogenesis and tectonic settings remain controversial. This study provides new geochronological and geochemical data on the Neoproterozoic bimodal magmatism from the eastern Himalayan orogen. In situ zircon U Pb dating revealed that the protoliths of amphibolites were emplaced at ca. 826 Ma and the granitic gneisses have crystallization ages of 825–820 Ma. The granitic gneisses exhibit geochemical features of A-type granites, with high initial (87Sr/86Sr)i ratio (0.7182–0.7394), low whole-rock eNd(t) (−8.4 to −6.6), and variable zircon eHf(t) (−7.4 to +1.0) values. They were probably generated by partial melting of the ancient lower crust with minor input of mantle components. The amphibolite samples are enriched in light rare earth elements (LREEs) and depleted in heavy rare earth elements (HREEs), suggesting an arc affinity. They have relatively high initial (87Sr/86Sr)i ratios (0.7113–0.7136), low whole-rock eNd(t) (−1.1 to 1.4) and a wide range of zircon eHf(t) (−4.1 to 8.3) values, indicating that the protoliths of amphibolites were likely generated by partial melting of an enriched subduction-modified continental lithospheric mantle. Their geochemical signatures are similar to typical back-arc basin basalts. The presence of coeval A-type granites and arc-related mafic rocks is probably due to the existence of a back-arc system. We argue that the Neoproterozoic bimodal magmatism is a product of back-arc extension initiated at an early stage, resulting from the rollback of the Mozambique Oceanic slab. Combined with previous studies on Neoproterozoic magmas from India and the Himalayas, we suggest that an extensive Neoproterozoic back-arc system may have existed along the northwestern margin of the Rodinia supercontinent. This theory supports a scenario of an Andean-type continental margin for the India-Himalayan terrane during the middle Neoproterozoic.

We present in-situ zircon laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb ages, whole-rock geochemistry, and Sr–Nd–Pb–Hf isotopes of the Mugagangri monzogranite in the southern margin of the Qiangtang Block, Tibet, western China. The zircons yield a U–Pb age of ca. 123 Ma. The hornblende-bearing monzogranite shows metaluminous to weak peraluminous and high-K calc-alkaline characteristics exemplified by high silica (SiO2 = 67.57–70.57 wt%), high aluminium (Al2O3 = 14.68–15.78 wt%), high potassium (K2O = 4.00–5.14 wt%), high alkali (K2O + Na2O = 7.88–8.62 wt%), and low calcium contents (CaO = 1.72–2.17 wt%), with the aluminium saturation index (A/CNK) ranging from 0.98 to 1.09, suggesting that the Mugagangri monzogranite is a metaluminous to weak peraluminous I-type high-K calc-alkaline granite. Geochemically, similar to the arc magmas, the monzogranite is enriched in large-ion lithophile elements, and relatively depleted in high-field-strength elements. The monzogranite displays relatively high(87Sr/86Sr)i values (0.70972–0.71240), uniform eNd(t) values (−2.24 to −3.40), variable zircon eHf(t) values (−14.1 to +8.0), and high radiogenic Pb isotopic values (206Pb/204Pb = 18.588–18.790, 207Pb/204Pb = 15.616–15.642, and 208Pb/204Pb = 38.838–39.053). These geochemical characteristics indicate that the monzogranite was derived from a mixed source comprising ancient crustal and mantle materials, and experienced frac- tional crystallization during emplacement. We propose that the parental magma of the Mugagangri monzogranite was most likely generated during northward subduction of the Bangong Coujiang Meso-Tethys Ocean.

The Xitieshan deposit (~ 64 Mt at 4.86% Zn, 4.16% Pb, 58 g/t Ag, and 0.68 g/t Au) is hosted by the Middle to Late Ordovician Tanjianshan Group of the North Qaidam tectonic metallogenic belt, NW China. This belt is characterized by island arc volcanic, ultra-high pressure (UHP) metamorphic and ophiolitic rocks. The Tanjianshan Group constitutes a succession of metamorphosed bimodal volcanic and sedimentary rocks, which are interpreted to have formed on the margin of a back-arc ocean basin between the Qaidam block and the Qilian block. Four stratigraphic units are identified within the Ordovician Tanjianshan Group. From northeast to southwest they are: 1) unit a, or the lower volcanic-sedimentary rocks, comprising bimodal volcanic rocks (unit a-1) and sedimentary rocks (unit a-2) ranging from carbonates to black carbonaceous schist; 2) unit b, or intermediate-mafic volcaniclastic rocks, characterized by intermediate to mafic volcaniclastic rocks intercalated with lamellar carbonaceous schist and minor marble lenses; 3) unit c, a purplish red sandy conglomerate that unconformably overlies unit b, representing the product of the foreland basin sedimentation during the Early Silurian; 4) unit d, or mafic volcanic rocks, from base to up, comprising the lower mafic volcaniclastic rocks (unit d-1), middle clastic sedimentary rocks (unit d-2), upper mafic volcaniclastic rocks (unit d-3), and uppermost mafic volcanic rocks (unit d-4). Unit a-2 hosts most of the massive sulfides whereas unit b contains subordinate amounts. The massive stratiform lenses constitute most of the Xitieshan deposit with significant amount of semi-massive and irregularly-shaped sulfides and minor amounts in stringer veins. Pyrite, galena and sphalerite are the dominant sulfide minerals, with subordinate pyrrhotite and chalcopyrite. Quartz is a dominant gangue mineral. Sericite, quartz, chlorite, and carbonate alteration of host rocks accompanies the mineralization. U-Pb zircon geochronology yields three ages of 454 Ma, 452 Ma and 451 Ma for the footwall felsic volcanic rocks in unit a-1, sedimentary host rocks in unit a-2 and hanging-wall unit b, respectively. The Xitieshan deposit is considered to be coeval with the sedimentation of unit a-2 and unit b of the Tanjianshan Group. The Xitieshan deposit has been intensely deformed during two phases (main ductile shear and minor ductile-brittle deformation). The main ductile shear deformation controls the general strike of the ore zones, whereas minor deformation controls the internal geometry of the ore bodies. 40 Ar- 39 Ar age of muscovite from mylonitized granitic gneisses in the ductile shear zone is ~ 399 Ma, which is interpreted to date the Xitieshan ductile shear zone, suggesting that Early Devonian metamorphism and deformation post-dated the Tanjianshan Group. The Xitieshan deposit has many features similar to that of the Bathurst district of Canada, the Iberian Pyrite Belt of Spain, the Wolverine volcanogenic massive sulfide deposit in Canada. Based on its tectonic setting, host-rock types, local geologic setting, metal grades, geochronology, temperatures and salinities of mineralizing fluid and source of sulfur, the Xitieshan deposit has features similar to sedimentary exhalative (SEDEX) and VMS deposits and is similar to volcanic and sediment-hosted massive sulfide (VSHMS) deposits.

In situ U–Pb geochronology, Lu–Hf isotopes and REE geochemical analyses of detrital zircons from Cambrian–Devonian sandstones in the Truong Son Belt, central Vietnam, are used to provide the information of provenance and tectonic evolution of the Indochina Block. The combined detrital zircon age spectra of all of the samples ranges from 3699 Ma to 443 Ma and shows with dominant age peaks at ca. 445 Ma and 964 Ma, along with a number of age populations at 618–532 Ma, 1160–1076 Ma, 1454 Ma, 1728 Ma and 2516 Ma. The zircon age populations are similar to those from time equivalent sedimentary sequences in continental blocks disintegrated from the East Gondwana during the Phanerozoic. The younger zircon grains with age peaks at ca. 445 Ma were apparently derived from middle Ordovician–Silurian igneous and metamorphic rocks in Indochina. Zircons with ages older than about 600 Ma were derived from other Gondwana terrains or recycled from the Precambrian basement of the Indochina Block. Similarities in the detrital zircon U–Pb ages suggest that Paleozoic strata in the Indochina, Yangtze, Cathaysia and Tethyan Himalayas has similar provenance. This is consistent with other geological constrains indicating that the Indochina Block was located close to Tethyan Himalaya, northern margin of the India, and northwestern Australia in Gondwana.

The Cuonadong deposit is located in the Cuonadong gneiss dome of the eastern Tethyan Himalaya and is characterized as a large- to superlarge-scale Sn polymetallic deposit in the Himalaya orogen. The mineralization pattern includes skarn W-Sn mineralization in the strong shear zone of the dome mantle, hydrothermal Sn-W veins controlled by north-south-trending rifts (NSTRs), and Be-Rb mineralization in pegmatitic leucogranite. The results of this study show that the zircon U-Pb age of undeformed (postkinematic) leucogranites is 15.5 ± 0.1 Ma (n = 28, MSWD = 1.4), the cassiterite U-Pb age of the vein-type Sn-W orebody is 14.3 ± 0.5 Ma (n = 40, MSWD = 3.2), and the muscovite Ar-Ar age of beryl-bearing pegmatitic leucogranite is 15.2 ± 0.2 Ma (MSWD = 1.5). The isotopic dating results demonstrate that the Cuonadong Sn-W-Be-Rb mineralization has a close genetic relationship with the Miocene (ca. 16–14 Ma) leucogranite magmatic hydrothermal activity in the Cuonadong dome. The deformed (synkinematic) two-mica granite (18 Ma) was cut by the Sn-W ore veins (14 Ma) faulted by NSTRs, indicating that the E-W-trending extension of the NSTRs initiated at ca. 18–14 Ma. The Himalaya leucogranite belongs to a highly fractionated granite with high Sn content (>15 ppm). In conclusion, the Himalaya leucogranite is considered to be tin granite in this study, and therefore, the Himalaya presents high potential for Sn polymetallic mineralization prospecting.

Petrological, geochemical and in-situ zircon U–Pb dating and Hf-isotope analyses have been carried out on a suite of basalt–andesite–rhyolite volcanic rocks exposed in the Liuluocun area, Hainan Island, SE China. Zircon analyses show that these volcanic rocks crystallized in the Early Cretaceous (ca. 102 Ma). The basalts are characterized by low MgO contents and mg-numbers but high rare earth element, high field strength element and large ion lithophile element contents and Nb–Ta negative anomalies. They have relatively uniform Sr–Nd isotope compositions with e Nd (t) values of − 4.09 to − 3.63. The andesites show enrichment of high field strength element and rare earth element with negligible Eu anomalies. They have e Nd (t) values of − 2.35 to − 3.88 and e Hf (t) values of − 9.73 to − 1.13. The rhyolites have high K 2 O and SiO 2 contents. They are characterized by prominent Eu, P and Ti negative anomalies and enrichment in large ion lithophile element, and show e Hf (t) values of − 7.51 to + 0.47 and e Nd (t) values of − 2.49 to − 2.69. Petrogenetic analysis indicates that the Liuluocun volcanic rocks were produced by incomplete reaction of the mantle wedge peridotite with felsic melts derived from partial melting of subducted sediment. All these characteristics, combined with geological observations, suggest that their formation was related to regional lithospheric extension in the South China Craton during the Early Cretaceous, which may have been caused by subduction of the Paleo-Pacific plate beneath the continental plate of China.

Neoproterozoic granitic rocks in the Dakendaban Group are widely distributed throughout the Xitieshan area as the old basement in North Qaidam, NW China. The granitic rocks are composed predominantly of K-feldspar, plagioclase, quartz, muscovite and biotite, with subordinate zircon, garnet, titanite and sillimanite. Two granitic rock samples yielded ages of 930 ± 6 Ma and 918 ± 6 Ma using LA-ICPMS zircon U–Pb dating, which are interpreted as the protolith formation age of the granitic rocks, and reflecting an important Neoproterozoic magmatic event in the Xitieshan area. Geochemical data suggest that the granitic rocks are characterized by high SiO2, K2O, and CaO/Na2O ratios (0.48–1.04), with LREE enrichment and strong Eu negative anomalies (Eu/Eu* = 0.44–0.51), and negative anomalies of Nb, Ta, Ti, Zr, and Hf. These rocks have consistent Nd isotope compositions with ɛNd(t) values ranging from −4.83 to −4.27, while the sample 2011ZJ18-3 yielded the negative ɛHf(t) values ranging from −6.7 to −1.3, and tDM2(Hf) model ages ranging from 1.9 to 2.2 Ga. These geochemical and zircon Lu–Hf isotopic features suggest that the granitic rocks in the Xitieshan area belong to the S-type granite, which were mainly derived from the partial melting of the Paleoproterozoic continental crust material (1.9–2.2 Ga) that were predominantly composed of metagreywackes and subordinate metapelitic sources. Based on the regional tectonic reconstruction, we propose that the studied rocks occurred as syn-orogeny on an active continental margin in a compressional environment, which resulted from the Neoproterozoic arc-continent collision and subsequently continent–continent collision, leading to the significant continental growth. The Early Neoproterozoic tectonothermal event in North Qaidam shares many affinities with that of the Tarim block and South China block (Yangtze block) that were associated with the final consolidation of block at the Jinning orogeny, showing an agreement with the formation of Rodinia. The Early Neoproterozoic S-type granitic magmatism in NW China, including the Qaidam and adjacent blocks, is an important episode of continental crust reworking.

Integrated in situ U–Pb dating and Hf-isotope analysis on detrital zircons from six sandstone samples from Hainan Island have been used to identify clastic sedimentary provenances, regional magmatic activity and crustal evolution processes. Four samples (2011XL-1, 2011JB-1, 09HN54 and 2011GB-1) are from previous mapped Silurian strata and the other two samples (2011TD-1 and 09HN39) belong to Ordovician and Cambrian strata, respectively. A total of 463 concordant U–Pb zircon analyses of the six samples define five major age populations: 2598–2320 Ma (a peak of 2480 Ma), 1944–1606 Ma (peak-1750 Ma), 1600–1406 Ma (peak-1502 Ma), 1288–902 Ma (peak-957 Ma), 470–427 Ma (peak-442 Ma) and two subordinate populations at 898–710 Ma (peak-730 Ma) and 618–513 Ma (peak-578 Ma). The combination of age peaks within the samples provide a record of igneous activity in the source region: the 2480 Ma peak is consistent with those ages reported for Neoarchean global continental growth; the 1944–1606 Ma population correlates with the time of assembly of the supercontinent Nuna (Columbia); the 1502 Ma peak with documented magmatic activity on Hainan Island; and the 1288–902 Ma and 898–710 Ma populations with global tectonothermal activity associated with assembly and breakup of Rodinia. Our data also reveal a 618–513 Ma population that may relate with the assembly of Gondwana. The distinctive age peak at 442 Ma indicates input from a region affected by the Kwangsian orogeny. The combined ages and Hf-isotope data for each population suggest that generation of juvenile crust occurred at 1900–1400 Ma, 940–740 Ma and 470–430 Ma. Most of the other age populations that display negative e Hf (t) values suggest reworking of older crust.

Zircon U–Pb geochronological, geochemical and petrological analyses have been carried out on the Xitian granite emplaced in the middle part of Shi-Hang zone, which is closely related to the economically important Xitian tungsten–tin deposit in Hunan Province, Southeast China. LA-ICP-MS zircon U–Pb dating of two representative samples yielded weighted means 206 Pb/ 238 U age of 151.7 ± 1.2 Ma and 151.8 ± 1.4 Ma. These granites are comprised mainly of K-feldspar, quartz, plagioclase, Fe-rich biotite and minor fluorite, and are characterized by enrichments in Rb, Th, REEs (total REE = 159–351 ppm), and HFSEs (e.g., Zr and Y) but depletions in Ba, Sr, P, Eu and Ti. They are metaluminous to weakly peraluminous and show a clear A-type granite geochemical signature with high SiO 2 (73.44–78.45 wt.%), total alkalis (Na 2 O + K 2 O = 2.89–8.98 wt.%), Fe 2 O 3 ∗ /MgO ratios and low P 2 O 5 , CaO, MgO and TiO 2 contents. In-situ zircon Hf isotope analysis suggests their e Hf ( t ) values ranging from –7.43 to –14.69. Sr–Nd isotope data show their e Nd ( t ) values in the range of –9.2 to –7.3, with corresponding T DM2 ages of 1.72–1.56 Ga. These characteristics indicate that the Xitian granite originated from partial melting of metamorphic basement rocks with a certain amount of mantle-derived materials. Combined with previous geochemical and isotopic data, it is derived that mantle–crust interaction was gradually enhanced from the early to late stages of magmatism. The ore-forming materials and fluids of the Xitian W–Sn deposit are mainly produced by the Early Yanshanian granitic magmatism, which is also responsible for the Late Jurassic (ca. 152 Ma) A-type granitic rocks that host the W–Sn polymetallic deposits distributed along the Shi-Hang zone, implying a significant Mesozoic extensional event in Southeast China likely caused by the subduction of the Paleo-Pacific plate.

The Yinggehai-Song Hong (Y-SH) Basin, located on the northwestern shelf of the South China Sea, is one of the world's largest pull-apart basins. In order to identify the provenance of the Upper Miocene to Quaternary sediments of the basin, ten sediment samples were collected from drill cores in the Dongfang gas field. U–Pb dating of detrital zircon grains extracted from the ten samples using a laser ablation inductively coupled mass spectrometer (LA-ICP-MS) yields ages ranging from the Archean to Cenozoic (2898 ± 46 Ma to 26 ± 1 Ma). The zircon U–Pb age spectra of the Upper Miocene to Quaternary show a similar pattern with major peaks clustered at ca. 32 Ma, ca. 99 Ma, ca. 160 Ma, ca. 247 Ma, ca. 422 Ma and three “broad” age groups, 600–1000 Ma, 1700–2100 Ma and 2200–2800 Ma, suggestive of a wide range of igneous rock ages in the source areas. The detrital zircon ages provide diagnostic criteria for identification of the various source areas and reveal that the detritus was derived from multiple sources. Comparison of the results with the rock types and their ages surrounding the potential source areas indicates that the clastic material was derived from three dominant age sources: (1) Yangtze Craton, (2) Hainan Island and (3) Indochina Block. The Yangtze Craton was a major and continuous source area contribution to the basin. Comparing the age characteristics and its source areas since 10 Ma, the largely stable provenance also suggests that if the Red River capture ever existed it should have happened before the Late Miocene.

The Tanjianshan Group, which was previously divided into a, b, c and d formations, has been controversial for a long time. It mainly distributes in the northern margin of Qaidam Basin and is an important early Paleozoic greenschist facies metamorphic volcanic sedimentary rock formation. Detailed field investigation and zircon LA-ICPMS U-Pb dating of the key strata suggest that the original lower part of a Formation (a-1) versus the original middle upper of d Formation (d-3 and d-4), the original upper part of a Formation (a-2) and b Formation versus the original lower part of d Formation (d-1 and d-2) of Tanjianshan Group are contemporaneous heterotopic facies volcanicclasolite deposit, respectively. The former formations formed during the middle-late Ordovician (463–458 Ma), while the latter ones formed in the late Ordovician (about 445 Ma). The original c formation of Tanjianshan Group, which formed after 430 Ma, is similar to the Maoniushan Formation of Kunlun Mountains and north Qaidam Basin. According to the rules of stratigraphic division and naming, new stratum formations of Tanjianshan Group are re-built and divided into Duancenggou (O1–2td), Zhongjiangou (O2–3tz) and Xitieshan (O3tx) formations. The original c Formation is separated from Tanjianshan Group and is renamed as the Wuminggou Formation (S3-D1w), which shows a discordant contact with underlying Tanjianshan Group and overlying Amunike Formation (D3a). The zircon U-Pb age frequency spectrogram of Tanjianshan Group indicates three prominent peaks of 430 Ma, 460 Ma and 908 Ma, which is consistent with the metamorphic and magmatic crystallization ages obtained from para- and orthogneisses in north Qaidam HP-UHP metamorphic belt, implying that strong Caledonian and Jinningian tectonic and magmatic events have ever happened in North Qaidam.

The Xitian tungsten–tin (W–Sn) polymetallic deposit, located in eastern Hunan Province, South China, is a recently explored region containing one of the largest W–Sn deposits in the Nanling W–Sn metallogenic province. The mineral zones in this deposit comprise skarn, greisen, structurally altered rock and quartz-vein types. The deposit is mainly hosted by Devonian dolomitic limestone at the contact with the Xitian granite complex. The Xitian granite complex consists of Indosinian (Late Triassic, 230–215 Ma) and Yanshanian (Late Jurassic–Early Cretaceous, 165–141 Ma) granites. Zircons from two samples of the Xitian granite dated using laser ablation-inductively coupled mass spectrometer (LA-ICPMS) U–Pb analysis yielded two ages of 225.6 ± 1.3 Ma and 151.8 ± 1.4 Ma, representing the emplacement ages of two episodic intrusions of the Xitian granite complex. Molybdenites separated from ore-bearing quartz-veins yielded a Re–Os isochron age of 149.7 ± 0.9 Ma, in excellent agreement with a weighted mean age of 150.3 ± 0.5 Ma. Two samples of muscovites from ore-bearing greisens yielded 40Ar/39Ar plateau ages of 149.5 ± 1.5 Ma and 149.4 ± 1.5 Ma, respectively. These isotopic ages obtained from hydrothermal minerals are slightly younger than the zircon U–Pb age of 151.8 ± 1.4 Ma of the Yanshanian granite in the Xitian area, indicating that the W–Sn mineralization is genetically related to the Late Jurassic magmatism. The Xitian deposit is a good example of the Early Yanshanian regional W–Sn ore-forming event (160–150 Ma) in the Nanling region. The relatively high Re contents (8.7 to 44.0 ppm, average of 30.5 ppm) in molybdenites suggest a mixture of mantle and crustal sources in the genesis of the ore-forming fluids and melts. Based upon previous geochemical studies of Early Yanshanian granite and regional geology, we argue that the Xitian W–Sn polymetallic deposit can be attributed to back-arc lithosphere extension in the region, which was probably triggered by the break-off of the flat-slab of the Palae-Pacific plate beneath the lithosphere.