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Initiation of Mariana-type oceanic subduction zones requires rheologically strong oceanic lithosphere, which developed through secular cooling of Earth's mantle. Here, we report a 518 Ma Mariana-type subduction initiation ophiolite from northern Tibet, which, along with compilation of similar ophiolites through Earth history, argues for the establishment of the modern plate tectonic regime by the early Cambrian. The ophiolite was formed during the subduction initiation of the Proto-Tethys Ocean that coincided with slab roll-back along the southern and western Gondwana margins at ca. 530-520 Ma. This global tectonic re-organization and the establishment of modern plate tectonic regime was likely controlled by secular cooling of the Earth, and facilitated by enhanced lubrication of subduction zones by sediments derived from widespread surface erosion of the extensive mountain ranges formed during Gondwana assembly. This time also corresponds to extreme events recorded in climate and surface proxies that herald formation of the contemporary Earth. This paper placed the identified Mariana type ophiolite within a global tectonic re-organization at ca. 530-520 Ma. Similar ophiolites, together with other geological and chemical proxies, newly constrained the timing of establishment of modern plate tectonics, along with its links to surficial changes that characterize the contemporary Earth. [ABSTRACT FROM AUTHOR]

Abstract The Central Asian Orogenic Belt (CAOB) was built up through protracted accretion and collision of a variety of terranes/micro-continents during Neoproterozoic–Mesozoic time. To understand potential links among Paleozoic subduction and accretionary processes that were operative during the development of the southeastern CAOB, we conducted a combined U-Pb and Hf-isotope analysis of detrital zircons from previously defined Devonian, Carboniferous and Early Permian strata in the Bengbatu area, Inner Mongolia. Detrital zircons from (meta-) sandstones in these strata commonly yield major Paleozoic age populations at ca. 300–261 Ma, 351–300 Ma and 517–419 Ma, and also give several Precambrian ages that range from 2687 Ma to 544 Ma. The youngest ages redefine the deposition of all these strata to be in the Middle Permian (Wordian–Capitanian) or later, much younger than previously considered. These ages, coupled with regional magmatic records, support an interpretation of most surrounding areas as possible detritus sources, including the Mongolian arcs to the north, the Northern Accretionary Orogen to the south, and the intervening Erenhot–Hegenshan Ophiolite Belt. Zircons with magmatic ages of ca. 500–350 Ma and ca. 300–261 Ma display a large range of ε Hf (t) values (−13.97 to +15.31), whereas ca. 350–300 Ma zircons are dominated by positive ε Hf (t) values (+0.14 to +16.00). These results support the occurrence of two significant shifts of the zircon ε Hf (t) values, which has tectonic implications for the understanding of the Carboniferous–Permian evolution of the southeastern CAOB. A marked shift from mixed to positive zircon ε Hf (t) values at 350–330 Ma likely manifests the incipient opening of the Hegenshan Ocean, due to the slab rollback of the subducting Paleo-Asian Oceanic lithosphere. Another shift from positive to mixed zircon ε Hf (t) values at ca. 300 Ma likely corresponds to a tectonic switch from syn-orogenic subduction-related to post-orogenic extensional setting, genetically related to the tectonic collapse of a formerly overthickened crust. Graphical abstract Image 1 Highlights • Previously defined Devonian–early Permian rocks were deposited in the mid-Permian or later. • Detrital sources include all surrounding arcs, ophiolites and orogenic belts. • Two changes between mixed and positive ε Hf (t) values occur at ∼350–330 Ma and ∼300 Ma. • The Hf isotope change at ∼350–330 Ma marks incipient opening of the Hegenshan Ocean. • The Hf isotope change at ∼300 Ma marks the initiation of post-orogenic extension. [ABSTRACT FROM AUTHOR]

Situated between the South Tianshan suture zone to the west and the Solonker suture zone to the east, the Yagan and Zhusileng-Hangwula arcs (YZHAs) in western Inner Mongolia in China occupy a critical place to investigate the tectonic history of the middle segment of the southern Central Asian Orogenic Belt (CAOB). In this work, field-based petrological studies and zircon U-Pb dating results reveal several episodes of granitic magmatism from 400 to 230 Ma in the YZHAs. Whole-rock geochemical and zircon Lu-Hf isotopic data indicate that all the 400-230 Ma granitoids underwent intensive fractional crystallization and were generated by magma mixing involving different proportions of mantle- and crust-derived materials. The ∼400 Ma monzogranites show (high-K) calc-alkaline affinities, akin to S-type granitoids. They were most likely generated in a postcollisional setting, corresponding to the assembly of the YZHAs before the Early Devonian. The 298-290 Ma granitoids belong to transitional I/S-type to A-type, whereas the 280-277 Ma granitoids are typical I-type. These Permian granitoids show increasingly evolved zircon εHf(t) values and formed from crust-mantle magma mixing, suggesting an advancing subduction setting. The ∼230 Ma monzogranites exhibiting fairly positive zircon εHf(t) values (+6.26 to +10.49) and high contents of mafic compositions and transition elements probably formed in a postcollisional setting after the assembly of the YZHAs and the Alxa Terrane. We infer that the final assembly of the middle segment of the southern CAOB probably occurred in the Early-Middle Permian. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB), as one of the largest accretionary orogens in the world, was built up through protracted accretion and collision of a variety of terranes due to the subduction and closure of the Paleo-Asian Ocean in the Neoproterozoic to Early Mesozoic. Located in the Uliastai continental margin of the southeastern CAOB, the Chagan Obo Temple area is essential for understanding the tectonic evolution of the southeastern part of the CAOB and its relation with the “Hegenshan Ocean”. In this study, detrital zircon U-Pb geochronology coupled with Hf isotopic analysis was performed on Paleozoic sedimentary strata in this area. Most detrital zircons from the studied samples possess oscillatory zoning and have Th/U ratios of 0.4-1.73, indicative of an igneous origin. Detrital zircons from the Ordovician to Devonian sedimentary strata yield a predominant age group at 511-490 Ma and subordinate age groups at 982-891 Ma, 834-790 Ma and ~ 574 Ma, and have a large spread of ε Hf (t) values (-20.77 to + 16.94). Carboniferous and Early Permian samples yield zircon U-Pb ages peaking at ~ 410 Ma and ~ 336 Ma, and have dominantly positive ε Hf (t) values (+ 1.30 to + 14.86). Such age populations and Hf isotopic signatures match those of magmatic rocks in the Northern Accretionary Orogen and the Mongolian arcs. A marked shift of provenance terranes from multiple sources to a single source and Hf isotope compositions from mixed to positive values occurred at some time in the Carboniferous. Such a shift implies that the Northern Accretionary Orogen was no longer a contributor of detritus in the Carboniferous to Early Permian, due to the opening of the “Hegenshan Ocean” possibly induced by the slab rollback of the subducting Paleo-Asian Ocean. [ABSTRACT FROM AUTHOR]

The Heilongjiang complex, extending along a suture zone between the Jiamusi and Songliao blocks in Northeast China, is composed mainly of blueschists, greenschists, meta-ultramafic rocks, quartzites, muscovite–albite schists and two-mica schists. Controversy has long surrounded the ages and tectonic settings of mafic rocks from the complex, which are crucial part of the complex. The lithological associations and their major and trace element compositions indicate that the mafic protoliths of the Yilan greenschists can be subdivided into alkali and tholeiitic basalts, which were derived from partial melting of a garnet-bearing and spinel-bearing mixed source, whereas the protoliths of the amphibolites are tholeiitic and were generated from the partial melting of spinel peridotite. Magmatic zircons from a tholeiitic amphibolite sample yielded a 206Pb/238U age of 256 ± 2 Ma, interpreted as its protolithic age. The sample also contains small amounts of older inherited zircons up to 344 Ma, which, together with its origin from shallow lithospheric mantle, indicate that the tholeiitic rocks were generated in a continental rift. The geochemical data suggest that further rifting led to the formation of an ocean between the Jiamusi and Songliao blocks, in which some oceanic islands developed, represented by the alkali basaltic protoliths of the Yilan greenschists. Magmatic zircons from an alkaline greenschist sample yielded a 206Pb/238U age of 162 ± 3.9 Ma, which, together with protolithic age of 141.8 ± 1 Ma previously obtained for the Yilian blueschist, support the model that the ocean between the Jiamusi and Songliao blocks closed at some time after ~ 141 Ma, not earlier at 210–180 Ma as previously considered. [ABSTRACT FROM AUTHOR]

The provenance of late Paleozoic siliciclastic sedimentary strata on the northern margin of the Tarim Craton and the South Tianshan Orogenic Belt provides important insights into subduction and collision processes during the formation of the southern Central Asian Orogenic Belt. Detrital zircons from Carboniferous and Permian sedimentary rocks in the South Tianshan belt show two predominant age populations of 500–400 and 305–270 Ma, and three subordinate clusters around ~ 2.5 Ga, 2.0–1.7 Ga, and 1.2–0.6 Ma. Such age patterns are similar to major magmatic episodes in the Tarim Craton but are distinct from those in the Central Tianshan–Yili Block, implying that the Carboniferous–Permian strata in the South Tianshan belt were deposited on the northern margin of the Tarim Craton. These data, in combination with Carboniferous passive margin deposition along the South Tianshan and northern Tarim regions and intense arc magmatism in the Central Tianshan area, support the northward subduction of the South Tianshan oceanic crust. The abrupt decrease of zircon ε Hf ( t ) values at ~ 310 Ma indicates the tectonic transformation from oceanic subduction to continental collision. However, syn- and post-collisional sediments in the South Tianshan and northern Tarim regions did not contain detritus from the Central Tianshan–Yili Block, as evidenced by the absence/paucity of 380–310 Ma detrital zircons in the late Paleozoic strata and by the stratigraphic record in the regions. Insignificant surface erosion and uplifting during the collision and (ultra-)high-pressure rock exhumation require divergence in the frontal wedge. We propose that the switch from a convergent to a divergent regime was triggered by the arrival of the Tarim mantle plume in the latest Carboniferous, which possibly had profound effects on regional sedimentation and exhumation of (ultra-)high-pressure rocks in the orogenic belt. [ABSTRACT FROM AUTHOR]

[Display omitted] During Carboniferous time, tremendous juvenile arc crust was formed in the southern Central Asian Orogenic Belt (CAOB), although its origin remains unclear. Herein, we presented zircon U-Pb-Hf and whole-rock geochemical and Sr-Nd isotopic data for a suite of volcanic and pyroclastic rocks from the Khan-Bogd area in southern Mongolia. These Carboniferous pyroclastic rocks generally have some early Paleozoic zircons, probably derived from the granitic and sedimentary rocks of the Lake Zone and the Gobi-Altai Zone to the north, indicative of a continental arc nature. In addition, they have a main zircon U-Pb age of ca. 370–330 Ma, positive Hf and Nd isotopes, and mafic-intermediate arc affinity, similar to the coeval arc magmatism. Moreover, the pyroclastic rocks of the northern area have more mafic and older volcanic components with depositional time (ca. 350–370 Ma; Visean and Bashkirian stages) earlier than that in the southern area (mainly ca. 350–315 Ma; Serpukhovian and Bashkirian stages). Combining a preexisting northward subduction supported by the available magnetotelluric data with a slab rollback model of the main oceanic basin of the Paleo-Asian Ocean (PAO) during Carboniferous and Triassic times, we infer that the Carboniferous arc magmatism was probably derived from a backarc ocean triggered by slab rollback. Thus, the juvenile arc volcanism of Mongolia, together with other areas (e.g., Junggar) in the southern CAOB, represented a significant lateral accretion that terminated after the Carboniferous due to a significant contraction of the PAO. [ABSTRACT FROM AUTHOR]

Some Asian blocks were welded into Gondwana, whereas their positions in Gondwana are controversial, especially the Tarim Craton. This is mainly because the Tarim Craton is largely occupied by the Taklamakan desert and only a few rocks crop out along its margins. In this study, we investigate previously little-studied early Neoproterozoic to late Silurian strata, compile up-to-date published data in South Tarim and compare provenance between potential terranes to locate the position of the Tarim Craton in Gondwana. In South Tarim, detrital zircons are characterized by two prominent peaks at 950–750 and 550–450 Ma. Their ε Hf(t) values range from −20 to 10 (72% negative values) and 12 to 5 (75% negative values), respectively. In West Australia, two main peaks at 700–500 and 1200–1100 Ma characterize Neoproterozoic to early Paleozoic strata and the 950–750 Ma population featuring South Tarim is absent. In Arabia-Iran, zircons from Neoproterozoic-Ordovician strata are characterized by 1000–500 Ma ages with a main peak at ca. 660 Ma and predominantly positive ε Hf(t) values (65%). Instead, zircons from Neoproterozoic-Ordovician strata in North India are dominated by two main peaks at 1000–800 and 600–490 Ma. Their ε Hf(t) values range from −20 to 10 (66% negative values), and − 15 to 5 (77% negative values), respectively. Therefore, well comparable age spectra and Hf isotopic compositions suggest a close linkage of South Tarim and North India in Gondwana. Additionally, our results also identify Mesoproterozoic basement rocks in the South Western Kunlun Terrane, southwestern Tarim. The 487 ± 7 Ma andesitic lava sample with ε Hf(t) values clustering 10 to 15 formed during retreating subduction indicates that the northward subduction of the Proto-Tethys oceanic lithosphere initiated prior to 487 ± 7 Ma • The Aqingyan Group is Ordovician in age and the Yesanggang Formation was deposited at 486–433 Ma; • The early Paleozoic strata in south Tarim were sourced from the coeval magmatic sources; • The South Western Kunlun contains a Mesoproterozoic basement; • Detrital zircon suggests a close linkage of south Tarim and north India in Gondwana. [ABSTRACT FROM AUTHOR]

In Northeast China, oceanic subduction between the Jiamusi and Songliao blocks remains topic of hot debate. The Heilongjiang Complex has been regarded as an accretionary belt resulting from the subduction of an intervening ocean between the two blocks. In this study, we carry out extensive geological, geochemical and geochronological investigations on the sedimentary rocks, amphibolites and blueschists from the Heilongjiang Complex. The detrital zircons from meta-sedimentary rocks yield U-Pb age spams ranging from 268 to 780 Ma. Whereas the interlayered amphibolites show negative Nb-Ta-Ti and positive Pb anomalies and have a protolithic age of 188.2 ± 1.0 Ma, suggesting a subduction zone or magmatic arc origin in the Jurassic. The elevated initial Sr isotopic ratios (0.708–0.711) and negative ε Nd (t) values (− 4.3 to − 1.3) provide further evidence of the modification by upper continental crust during the magma ascending. LREE/HREE and MREE/HREE ratios suggest that the magma was likely derived from the mixing of lithospheric and asthenospheric melts. The presence of low Th/Ce (0.04–0.12) and Hf/Sm (0.35–0.55), but high Zr/Hf (35.4–43.4) and Pb/Ce (0.25–0.49) ratios strongly implies a contribution from subducted sediments. The identification of active continental margin type magmas of Early Jurassic age suggests that the subduction of the oceanic plate between the Jiamusi and Songliao blocks may have started around Early Jurassic time. In addition, the blueschists have a protolithic age of 186 ± 1.1 Ma and display geochemical affinities of oceanic island basalts, suggesting that the ocean between the Jiamusi and Songliao blocks closed sometime after 186 Ma. Mineral 40 Ar/ 39 Ar dating results from the Heilongjiang Complex further indicate that blueschist- to greenschist-facies metamorphism occurred in the Middle to Late Jurassic (158–175 Ma), marking the onset of termination of the oceanic subduction. [ABSTRACT FROM AUTHOR]

The Heilongjiang Complex is a blueschist facies metamorphic belt located within the Zhangguangcailing Orogen between the Jiamusi and Songliao blocks in Northeast China. This complex has been regarded as an accretionary belt related to the subduction of an intervening oceanic domain between the two blocks. However, the timing of ocean closure and final amalgamation has not been well constrained, with different models arguing for a period of 210–180 Ma or sometime after ~ 140 Ma. This work reports in-situ detrital zircon U–Pb and Hf isotopic analyses of meta-sedimentary rocks from the Heilongjiang Complex. Detrital zircons from seven meta-sedimentary rocks samples yield U–Pb ages spanning from 1690 to 167 Ma, with main populations matching those of multi-phase magmatism in the Jiamusi and Songliao blocks. Several Precambrian age groups (600 Ma, 700 Ma, 900 Ma, 960 Ma, 1200 Ma, and 1300 Ma) are consistent with the inherited zircons from the mafic rocks in the Heilongjiang Complex. A comparison with compiled data of magmatic rocks suggests that the two blocks may have been connected to each other during Permian time. Detrital zircon dating of all siliciclastic rocks yielded the youngest age component of ~ 170 Ma, suggesting that the latest deposition of the mica schists happened at some time after ~ 170 Ma. We propose that the Jiamusi and Songliao blocks once existed as a single block around Late Permian, which underwent a rifting event in the Permian to form a rifting basin that was subsequently evolved into an oceanic domain (Heilongjiang Ocean). The closure of the Heilongjiang Ocean occurred after ~ 170 Ma. [ABSTRACT FROM AUTHOR]

The Alxa Terrane is situated in a key area between the North China and Tarim cratons. Paleozoic magmatic records in this terrane place important constraints on the subduction processes of the southern Paleo-Asian Ocean. New data of zircon U-Pb ages and whole-rock elemental and isotopic data reveal two groups of intermediate to felsic plutons in the Alxa Terrane. One group consists of diorites and granitoids that were emplaced at ca. 460–440 Ma and characterized by lower Al 2 O 3 /TiO 2 ratios and higher TiO 2 contents, implying high temperature–low pressure crystallization conditions and a shallow source region. The second group is dominated by granitoids aged at ca. 420–407 Ma and displays high Sr and Ba, low Y and high rare earth elements, with very high Sr/Y ratios and mostly positive Eu anomalies. These characteristics imply low temperature–high pressure crystallization conditions and source regions at deep crustal levels where garnet is stable in the residual phase. Both of the two groups are mostly calc-alkaline to high-K calc-alkaline, depleted in Nb, Ta and Ti and enriched in Ba, K and Sr, indicative of an arc affinity most likely related to the southward subduction of the Paleo-Asian Ocean. Zircon ε Hf (t) and whole-rock ε Nd (t) values of these magmatic rocks decrease from 458 Ma to 440 Ma and increase from 417 Ma to 407 Ma, whereas whole-rock initial 87 Sr/ 86 Sr ratios display an opposite trend. Such an isotopic change suggests a tectonic switch from an advancing to a retreating subduction regime at ~ 407 Ma. Synthesized data from this and previous studies suggest that the 460–400 Ma magmatic arc in the Alxa Terrane represented the western extension of the Paleozoic arc belt on the northern margin of the North China Craton. [ABSTRACT FROM AUTHOR]

Abstract: As part of the Xiong''er volcanic belt along the southern margin of the North China Craton, volcanic rocks in the Xiaoshan and Waifangshan areas have a compositional range from the basaltic andesite, andesite, dacite to rhyolite, which display consistent variation trends in terms of their major and trace elements and Sr–Nd isotopic compositions. The variable Yb contents with nearly constant La/Yb and Tb/Yb ratios of volcanic rocks in two areas suggest that the fractional crystallization may have played an important role in the differentiation from the basaltic andesite, through andesite and dacite, to rhyolite. The volcanic rocks in these two areas are characterized by the LILE and LREE enrichments and negative HFSE anomalies, implying hydrous melting of a mantle wedge in a subduction zone. Variable Sr/Nd ratios of the basaltic andesite and andesite are interpreted as a result of the fluid addition from a subducting slab. Non-radiogenic Nd isotopic compositions as well as high Zr/Y and Nb/Y ratios suggest that the volcanic rocks in these areas were derived from an enriched mantle source. On the other hand, the volcanic rocks of the basaltic andesite and andesite possess markedly higher Fe–Ti and HFSE concentrations than those of typical intra-oceanic arcs, implying that the mantle source from which the volcanic rocks were derived was metasomatised by siliceous melts during the Archean to Paleoproterozoic subduction/collision in the Trans-North China Orogen. These data suggest that in the Paleo-Mesoproterozoic, the southern margin of the North China Craton was most likely an Andean-type continental arc in which slab dehydration not only induced the melting of a pre-existing metasomatised mantle source, but also released LILE-enriched fluids into the mantle source, masking the inherent HFSE-enriched characteristics of the volcanic rocks along the southern margin of the craton. The results of this study indicate that the North China Craton, like many other continental components (e.g. North America, Greenland, Baltica, Amazonia, Australia, etc.) of the supercontinent Columbia (Nuna), also underwent a subduction-related outgrowth along its southern margin during the Paleo-Mesoproterozoic time. [Copyright &y& Elsevier]

The Neoproterozoic Jiangnan accretionary orogenic belt recorded the accretion and collision of the Yangtze and Cathaysia blocks to form a stablized South China Block, but related geometry and kinematics is poorly constrained, leading to largely varied tectonic models. Here, we present detailed field investigation and kinematic analysis of the plutonic-metamorphic complexes in the Yuanbaoshan and Sanfang areas of the west Jiangnan orogenic belt, which enables identification of extensional granite-cored domes. In the dome margins, down-dipping lineations display a radial pattern and dome dominated foliations are extensively developed. The shearing structures within the plutonic-metamorphic complexes display extensional shearing surrounding the Yuanbaoshan and Sanfang granitic dome cores. Gneissic granites and massive ones from both the Yuanbaoshan and Sanfang plutons yield comparable crystallization ages of ca. 835–823 Ma that are within age errors of each other, as are the sheared recrystallized asymmetric quartz veins and mylonites dated at 831 Ma. Overall ages of the deformed Sibao Group and the undeformed overlying Danzhou Group, along with those of the granite plutons and mylonites, suggest formation of the granite-cored domes at ca. 835–823 Ma, coeval to the timing of emplacement of the granitic plutons. Locally, top-to-the-E thrusting structures are also observed in the west Yuanbaoshan and Sanfang areas and are inferred as at ca. 860–835 Ma, coinciding well with E- or SE- directed structures developed elsewhere in the Jiangnan orogenic belt, but in contrast with doming extensional shearing structures. Therefore, overall geometry and kinematics in the west Jiangnan belt indicate development of granitic dome related extensional ductile shearing deformation dated at ca. 835–823 Ma and a possible top-to-the-E compressional ductile thrusting deformation within 860–835 Ma. Given the previously inferred regional geology observations, along with age and chemical data across the Jiangnan orogenic belt, the dominant extensional shearing deformation in the region argue for a slab roll-back event within an accretionary belt, typical of domes-and-basins structures formed in accretionary convergent continental margin. The top-to-the-E thrusting is here interpreted as corresponding to compressional regime generated by the west directed subduction of oceanic crust beneath the northern Guangxi continental margin arc in the west Jiangnan orogenic belt. • Two stages of Neoproterozoic ductile deformation identified in the west Jiangnan accretionary orogenic belt. • The ca. 835–823 Ma extensional domes-and-basins were generated by a slab roll-back event in an accretionary belt. • The ca. 860–835 Ma top-to-the-E thrusting indicates west directed subduction beneath the western Jiangnan belt. [ABSTRACT FROM AUTHOR]

East Junggar is a key element of the southwestern Central Asian Orogenic Belt and the subject of debate relating to the initiation of accretion during the early Palaeozoic. We present zircon U Pb ages, geochemistry and Sr–Nd–Hf isotopic compositions of early Palaeozoic andesitic rocks from the Kayishekuola area, northern East Junggar, NW China. The volcanic rocks consist of andesites and basaltic andesites, which yielded zircon U Pb ages of 466–422 Ma. Andesites with ages of ca. 466 Ma were probably part of the earliest magmatic arc within northern East Junggar. These andesitic rocks are medium-K and calc-alkaline, with high SiO 2 (55.02–58.59 wt%), Na 2 O + K 2 O (3.86–5.63 wt%), and Al 2 O 3 (16.04–17.01 wt%) contents. They are enriched in the large-ion-lithophile elements and depleted in Nb, Ta, and Ti, consistent with an arc origin related to subduction of the Paleo-Asian Ocean. They have positive whole-rock ε Nd (t) and zircon ε Hf (t) values (3.8–4.3 and 9.7–15.3, respectively). These features are consistent with production of primary magmas by partial melting of depleted mantle modified by subduction. Based on these data, we infer that the Yemaquan arc formed from island arc-related rocks from ca. 466 Ma and records advancing subduction and associated crustal growth during the early Palaeozoic, and retreating subduction during the Early Devonian. Unlabelled Image • The 466 Ma andesites probably recorded the earliest magmatic arc event in East Junggar. • The 466–422 Ma mantle-derived andesites formed in an oceanic island arc setting. • Subduction beneath East Junggar advanced from 466 to 422 Ma. • Retreating subduction beneath East Junggar occurred during the Early Devonian. [ABSTRACT FROM AUTHOR]