The eastern segment of the Central Asian Orogenic Belt in NE China is considered to have been welded along the Changchun-Yanji suture following the closure of the Paleo-Asian Ocean. However, the timing of the closure of the Paleo-Asian Ocean between the North China Craton (NCC) and the Songliao Terrane remains highly debated. The Permo-Carboniferous sediments across the Changchun-Yanji suture are key to addressing this issue. The sediments from the Luquantun Formation are dominated by the Devonian to Carboniferous zircons, with peaks at 376, 354 and 326 Ma. Based on detrital zircon ages and fossil assemblages, the Luquantun Formation was probably deposited during the Early to Late Carboniferous. The detrital zircons generated epsilon Hf(t) values ranging from -19.0 to +7.4 and were probably derived from the NCC and its northern accretionary belt. In contrast, the detrital zircons from the Fanjiatun, Yilaxi and Yangjiagou formations gave youngest peak ages of 258, 257 and 254-259 Ma, respectively. These formations were probably deposited during the Late Permian, based on these ages and previous studies. These Upper Permian sediments contain zircon ages spanning from the Precambrian to the Palaeozoic, with epsilon Hf(t) values ranging from -22.0 to +12.0, indicating a mixed provenance from the Songliao Terrane to the north and the NCC together with its northern accretionary belt to the south. Based on the provenance analysis presented above, along with the Late Permian flora mixing, collisional granitoids, and metamorphic rocks, the closure of the Paleo-Asian Ocean probably occurred during the Late Permian, at least in the Changchun area.

Detrital zircon and apatite U-Pb-Hf isotope and trace element analyses of the late Mesoproterozoic to early Neoproterozoic strata in southern Jilin provide detailed information on the sediment provenance and tectonic setting of the northeastern margin of the North China Craton (NCC). Here, we present U-Pb and Lu-Hf analyses of 712 detrital zircons, and U-Pb analyses of 347 detrital apatites from the Baifangzi, Diaoyutai and Qiaotou formations. The Baifangzi and Diaoyutai formations are dominated by Neoarchean (2.5-2.6 Ga) and Paleoproterozoic (1.8-1.9 Ga) zircons, indicating a predominant NCC provenance. The Qiaotou Formation is dominated by Mesoproterozoic (1.5-1.7 Ga and 1.1-1.3 Ga) zircons with mainly positive epsilon Hf(t) values, which are similar to those from eastern Laurentia, implying a significant provenance transition. The detrital apatite age spectra of the Baifangzi and Diaoyutai Formations show major populations at 1.8-1.9 Ga and 1.1-1.3 Ga. Based on their trace element compositions, the Mesoproterozoic apatites were mainly sourced from metamorphic rocks, indicating regional metamorphism occurred in the NCC during 1.1-1.3 Ga. Combining these data with regional studies, we propose that the NCC was adjacent to eastern Laurentia during the assembly of the Rodinia supercontinent.

In deep mining, high temperature and humidity affect coal properties and spontaneous combustion. A closed oxygen consumption experiment was conducted on coal from Hongyang No. 2 mine. GCMC and MD techniques analyzed O2 adsorption/desorption dynamics under varying water injection and temperature conditions. Results indicate that with rising temperature and decreasing water content, oxygen uptake, CO generation, and coal's oxidative heat emission intensity increase exponentially. Molecular simulation shows H2O displaces oxygen by occupying adsorption sites. Water injection promotes oxygen release from coal, with more infusion volume leading to greater promotion. In high-temperature or high-water-content systems, the root-mean-square displacement and diffusion coefficient of O2 are higher than in low-temperature or low-water-content systems. Increased water injection raises the average directional change and diffusion coefficient of O2, enhancing its activity. Rising temperature and reduced water content effectively promote O2 desorption, indicating a stronger coal spontaneous combustion tendency under hygrothermal effects. This study, to explore the reasons for the disparity in the likelihood of spontaneous combustion between raw coal and wet thermal effect from macro and micro perspectives by combining experiment and simulation. The findings of the study can offer a theoretical foundation for the fire prevention technology in goaf.

The timing of the end-Permian mass extinction can be established from astronomically controlled climate cycles recorded in continuous marine sedimentary sections. The high-resolution cyclostratigraphic analysis is carried out on the deep-water Permian-Triassic boundary (PTB) sequence at the Rencunping section, Sangzhi County, South China. Physical and chemical proxy records reveal the presence of the complete suite of orbital frequencies in the Milankovitch bands, providing strong evidence for 405-kyr and 100-kyr eccentricity forcing throughout the Permian-Triassic boundary intervals. Floating astronomical time scales (ATS) are established for the discussion and comparison on the late Permian mass extinction and crisis between deep-water and shallow-water sections. Here we estimate durations of 2268 kyr for Changhsingian stage, 609 kyr for the Changhsingian conodont Clarkina yini Zone, and 1316 kyr for the ammonoid Pseudotirolites-Rotodiscoceras Zone, based on 405-kyr astronomical eccentricity tuning. Previous studies revealed that the biotic and environmental depletion began in deep waters earlier than the crisis in shallow waters. This study suggests that the extinction and environmental deterioration in deep waters started at least about 270 kyr before the PTB and 66-101 kyr earlier than the counterpart in shallow water. The deterioration is primarily explained as associated with frequent volcanism and its induced cascade of negative environmental and ecological effects. The volcanism was triggered by the subduction of Paleotethyan Ocean in South China.

Petrological, geochronological, and geochemical data from the volcano-sedimentary sequences, granitoids, and ophiolite relics of central Inner Mongolia, China, were used to reconstruct the subduction and final closure of the Hegenshan Ocean. Geochronological dating and compilation reveal four phases (ca. 360-355 Ma, 348-320 Ma, 320-310 Ma, and 310-275 Ma) of magmatism in the Uliastai continental margin. The ca. 356 Ma I-type Halatumiao granodiorite and Amanwusu ophiolite relics are subduction-related, and the Halatumiao granodiorite provides solid evidence of the northward subduction of the Hegenshan Ocean beneath the Uliastai continental margin at ca. 360-355 Ma. The ca. 348-320 Ma and 320-310 Ma volcanic rocks and granitoids constitute two linear magmatic belts roughly parallel to the ErenhotHegenshan ophiolite belt, which record two phases of continental arc magmatism in the Uliastai continental margin. Overall, the ca. 360-310 Ma arc magmatism shows landward migration and then oceanward migration in the Uliastai continental margin, which indicates advancing subduction and subsequent slab steepening of the Hegenshan Ocean. By contrast, the ca. 310-275 Ma magmatic rocks are dominated by I- and A-type felsic volcanic rocks, granites, and dikes, which are post-accretionary, extension-related, and pervasive in the Uliastai continental margin and Erenhot-Hegenshan ophiolite belt. A provenance shift was identified between the Benbatu and Amushan formations of the Amanwusu area of the Erenhot-Hegenshan ophiolite belt. The early detritus was derived from the early Paleozoic rocks in the Sonid Zuoqi arc belt, whereas the late detritus originated from the Early Carboniferous ophiolite relics in the Erenhot-Hegenshan ophiolite belt. The provenance shift and emplacement of pervasive extension-related magmatic rocks imply a Late Carboniferous closure of the Hegenshan Ocean. The Late Carboniferous oceanic closure event in the north of the southeast Central Asian Orogenic Belt is also evidenced by the transition of Hf isotopic composition of zircons dated between ca. 360-310 Ma and 310-275 Ma.

Early Cretaceous intraplate volcanic rocks are widespread in NE Asia, but their origin remains controversial. This work presents zircon U-Pb ages, whole-rock element and Sr- Nd isotope data for mafic volcanic rocks from the Erlian Basin, a wide rift basin in NE Asia. There were two episodes of Early Cretaceous mafic volcanism in the Erlian Basin, and the eruptions show contrasting geochemical com- positions. The early mafic volcanic rocks, with U-Pb ages of ca. 140-135 Ma, show slightly depleted Sr-Nd isotope compositions (I Sr (t) = 0.7042-0.7052; epsilon Nd (t) = + 0.82 to + 3.0) and arc-like trace-element composi- tions, which are derived from subduction- related fluid/melt metasomatized lithosphere mantle. The late mafic volcanic rocks (dated at ca. 125 Ma) have enriched Sr-Nd isotopes (I Sr (t) = 0.7055-0.7077; epsilon Nd (t) = - 0.50 to - 2.67) and oceanic-island basalt (OIB)-like trace-element compositions, revealing the metasomatism of melts from crustal materi- als and asthenosphere mantle. The two types of mafic volcanic rocks may record the in- teractions of the mantle and melts from the subducted paleo-Pacific oceanic slab at dif- ferent depths. The landward-then-oceanward migration pattern of the Mesozoic volcanism from NE Asia can be explained by the flat sub- duction and subsequent slab roll-back of the Paleo-Pacific Ocean, consistent with migra- tion patterns from the North China Craton and South China Block, implying similar Ju- rassic-Cretaceous subduction evolution along the entire East Asia margin. Some Late Juras- sic to Early Cretaceous dates from east Mon- golia and the southern margin of the Erlian Basin diverge from this trajectory. In combi- nation with previous studies, we suggest that the Early Cretaceous pervasive intraplate vol- canism in the Erlian Basin and adjacent areas of NE Asia mainly resulted from the slab roll- back of the Paleo-Pacific Ocean with a com- bined effect from the post-collision extension of the Mongol-Okhotsk orogen.

Identifying the petrogenesis and geodynamic mechanism of the Early Permian igneous rocks widely distributed in the Inner Mongolia-Daxing'an Orogenic Belt (IMDOB) is crucial for understanding the tectonic evolution of the southeastern Central Asian Orogenic Belt. In this study, a combined study of petrology, geochronology, and geochemistry of Early Permian volcanic-plutonic rocks from the Uliastai continental margin, northern IMDOB, was conducted aiming to constrain their petrogenesis and tectonic setting. The U-Pb zircon data for the magmatic zircons indicate that the Baoligaomiao Formation (BG Fm.) volcanic rocks, including felsic and mafic rocks, erupted at approximately 298-285 Ma, and quartz monzonite porphyries that intruded the BG Fm. were emplaced at approximately 292 Ma. The mafic volcanic rocks exhibit intraplate nature with basaltic composi-tions transitional between the calcalkaline and shoshonite series. The geochemical behavior and isotopic data of these volcanic rocks reflect a depleted lithospheric mantle source metasomatized by fluids released from the stagnant slab. Felsic volcanics and quartz monzonite porphyries show affinities with A-type granites and are derived from the partial melting of juvenile crustal materials. Moreover, we suggest that the Early Permian magmatism formed in a post-collisional extensional setting, which is the continuation of the Late Carboniferous extension and was induced by the lithospheric collapse after the slab break-off of the Hegenshan Ocean. Notably, the felsic rocks formed after 290 Ma, with affinity changing from A(2)-type to A1-type granite, and approximately 288 Ma mafic volcanic rocks exhibited intraplate characteristics. These changes, combined with the development of coeval bimodal volcanic rocks and dike swarms, suggest that the tectonic setting at the end of the Early Permian in the northern IMDOB may have gradually transferred to an intraplate environment.

This study presents a comprehensive analysis of zircon U-Pb-Hf isotopic and whole-rock geochemical data of Carboniferous-Early Permian felsic igneous rocks from the Uliastai continental margin (UCM), southeastern Central Asian Orogenic Belt, to constrain the amalgamation of the Inner Mongolia-Daxing'an Orogenic Belt (IMDOB) in the late Paleozoic. Zircon laser ablation inductively coupled plasma mass spectrometry U-Pb ages of monzogranite, granite porphyry, felsic volcanic rock, and alkali feldspar granite reveal three stages of magmatism in the Early Carboniferous (ca. 336-320 Ma), Late Carboniferous (ca. 311-307 Ma), and Early Permian (ca. 298 Ma). The Early Carboniferous igneous rocks, including monzogranites and later granite porphyries, exhibit affinity with the high-K calc-alkaline highly fractionated I-type granite, and are depleted in high-field-strength elements and enriched in large-ion lithophile elements. Their zircon epsilon(Hf)(t) values of the Early Carboniferous rocks range from +4.6 to +9.1, indicating that they were generated by partial melting of the juvenile crustal materials in a north-dipping subduction-related environment along with the opening of the Hegenshan Ocean. The Late Carboniferous felsic volcanic rocks are highly fractionated high-K calc-alkaline to alkali-calcic I-and A-type granitoids, with relatively strong peraluminous affinities. Considering the zircon epsilon(Hf)(t) values (+6.2 to +10.6) and relatively low Rb/Ba (0.71-3.57) and Rb/Sr (4.18-8.12) ratios, they were likely derived from a juvenile crust and are comparable to partial melts of clay-poor but plagioclase-rich metaigneous rocks. Notably, the A-type granitoids are gradually increasing in the UCM after 311 Ma, and these magmatic rocks have markedly increased zircon saturation temperatures and (K2O + Na2O)/CaO ratios. These changes may result from the slab break-off of the Hegenshan Ocean, and the Late Carboniferous felsic volcanic rocks were formed in a post-collisional setting. The Early Permian alkali feldspar granites are characterized by typical A-type granite geochemistry, with high Ga/Al ratios; low MgO, Cr, Co, and Ni contents; and high zircon saturation temperatures. These rocks have positive epsilon(Hf)(t) values of +10.2 to +12.7 and record an intracontinental extension setting. In combination with the regional geology, the Late Carboniferous post-collisional magmatic rocks suggest that a change from a subduction-related continental margin to a post-collisional tectonic regime might have occurred in the UCM before 311 Ma.

Permo-Carboniferous provenance shifts at the northern margin of the North China Craton (NCC) were reconstructed. The reconstruction was based on the detrital zircon U-Pb-Hf data from Late Paleozoic sandstones from Ondor Sum and Wude in the Southern Orogenic Belt (SOB) of the Southeast Central Asian Orogenic Belt (SE CAOB). Sandstone samples from the Lower Devonian Naqing Formation, Upper Carboniferous Hailasiamu Formation, and the first and second members of the Upper Carboniferous Amushan Formation in Ondor Sum present a nearly unimodal detrital zircon age grouping (c. 380-520 Ma), and they have similar zircon Hf isotopic compositions with igneous rocks in the SOB, implying that their provenance was from the SOB region. In contrast, samples in the same area from the third to fifth members of the Lower Permian Amushan Formation and the Lower Permian Sanmianjing Formation contain multimodal age groupings, with the ages mainly concentrated at the Late Carboniferous-Early Permian, Neoarchean, and Paleoproterozoic. The coexistence of Neoarchean and Paleoproterozoic grains suggests that the NCC could be a reliable source. In addition, the Hf isotopic composition of the Late Carboniferous-Early Permian zircons overlap with those from the NCC, and therefore, it is concluded that there were Permo-Carboniferous provenance shifts from the SOB to the NCC for the sandstones from the Upper Paleozoic in the Ondor Sum area. Late Carboniferous and Early Devonian sandstone samples from Wude had sediment contributions from both the SOB and the NCC, with detrital zircon grains from the SOB constituting the majority. Whereas, the Early Permian samples from this area contained sediment contributions predominantly from the NCC. We suggest that the Permo-Carboniferous provenance shifts were the result of significant local subsidence of the SOB, and the uplift of the Inner Mongolia Paleo-Uplift after the Early Devonian collision between the Bainaimiao arc belt and the NCC. (c) 2021 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The early to mid-Paleozoic subduction-induced terrane accretion along the northern margin of the North China Craton is not well understood. To address this issue, we investigate the magmatic and sedimentary records, including both new and previously published geochemical, Sr-Nd isotopic, and zircon U-Pb-Hf isotopic data from the Bainaimiao Arc. The collected gabbro-diorites and granitoids have been dated to 431-453 Ma. The gabbro-diorites have high Mg/(Mg + Fe) molar ratios (44.41-73.39); depleted Nb, Ta and Ti; and negative epsilon(Nd)(t) values (-9.43--6.80). They were derived from a mantle wedge metasomatized by subduction-derived fluids with crustal contamination. The granitoids are characterized by high silica, low to high K, low Fe and Mg contents, strong fractionation of rare earth elements, and positive epsilon(Hf)(t) values (+1.42-+8.19). They were derived from crustal melts with juvenile additions. The clastic rocks from the Baoerhantu Group and Xibiehe Formation are dominated by early Paleozoic zircons, whereas those from the Bainaimiao Group are dominated by early Paleozoic and Precambrian zircons. Detrital zircon geochronology and field geology confirm their deposition in early to mid-Paleozoic. The U-Pb ages and petrographic and geochemical analyses indicate that the clastic rocks were deposited in arc-related basins with felsic sources from the Bainaimiao Arc. The xenocrystic and detrital zircons in the magmatic and clastic rocks, respectively, imply a Precambrian basement for the Bainaimiao Arc. The early Paleozoic magmatic rocks of the Bainaimiao Arc show secular changes with decreasing age: increasing K2O contents and Sr/Y ratios and decreasing Fe2O3T + MgO contents and epsilon(Hf)(t) and epsilon(Nd)(t) values. This is likely in response to advancing subduction and related crustal thickening. Accordingly, the following tectono-paleogeographic model was proposed for the Bainaimiao Arc: (a) similar to 500-455 Ma initial subduction and juvenile arc development, (b) similar to 455-415 Ma continuous subduction with mature arc development, and (c) similar to 415-400 Ma accretion to the North China Craton. (c) 2019 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Reconstructing the Late Palaeozoic tectonic process of the Hegenshan Ophiolite Belt is critical for evaluating the protracted accretion and collision history of the south‐eastern Central Asian Orogenic Belt. The Carboniferous–Permian sedimentary rocks near the Erenhot area are key to revealing the evolutionary history of the Hegenshan Ocean. In this study, new stratigraphic, geochemical, and detrital zircon U–Pb age analyses were conducted on three Carboniferous–Early Permian strata (viz., Halatumiao, Amushan, and Benbatu formations). Deposition of the Halatumiao Formation began around 313 Ma, inferred from a zircon U–Pb age from a lower tuff layer. The end of deposition is constrained by two later intrusive high‐K granite plutons that give ages of 277–285 Ma. The predominant detrital zircon group in these strata is characterized by ages of 340–290 Ma, high positive εHf(t) values, and juvenile TDM2 ages, which suggest adjacent and unitary juvenile provenances. The Halatumiao Formation mainly consists of blackish fine‐grained sedimentary rocks with a thickness of 6–7 km implying a high sedimentation rate and a stable hydrodynamic condition. Thus, the Halatumiao Formation most likely indicates the existence of a deep and wide ocean basin under an effect of long‐lived and continuous extension. The Amushan Formation has a comparable depositional age to the Halatumiao Formation, based on three detrital zircon Palaeozoic age populations with peaks of 317, 389, and 441 Ma, but contains more complex provenances. The Benbatu Formation has an earlier deposition age between ca. 324 and 314 Ma. Its detrital zircons yield a predominant age group at around 410–440 Ma but lack syn‐sedimentary Late Palaeozoic age. Unlike the Halatumiao Formation, the two other formations are considerably smaller in terms of their deposition thickness and outcrop area. The transition from Benbatu to Amushan and Halatumiao formations records the development of a gradually deeper and wider ocean basin in response to a back‐arc extensional setting from the Late Carboniferous to the Early Permian.

The southeastern part of the Central Asian Orogenic Belt (CAOB), which records the collision of the North China Block (NCB) with the South Mongolian microcontinent, is a key area for reconstructing the tectonic history of the CAOB. Controversy persists regarding the timing of the final structural amalgamation of the region; therefore, it remains unclear whether the Late Paleozoic thick volcanic successions were generated in a subduction or post-orogenic environment. Redefining the age of the formation and analyzing the geochemical compositions of these volcanic rocks can provide clues regarding the regional tectonic evolution during the Late Paleozoic and place constraints on the closure time of the Paleo-Asian Ocean. In this study, we present geochemical, geochronologic, and Sr–Nd isotopic data for 29 volcanic rock samples from the Elitu Formation in Xianghuangqi, central Inner Mongolia. The Elitu volcanic rocks have latest early-to-middle Permian ages between 272 and 268 Ma. Most of the mafic–intermediate and felsic rocks show K-normal and high-K calc-alkaline characteristics. Melting is considered to be due to large scale upwelling of the metasomatic lithospheric mantle and different degrees of melting of the thickened lower crust. The northern margin of the NCB, which represents the southeastern boundary of the CAOB, records transtensional and, subsequently, extensional tectonics associated with late Carboniferous to middle Permian volcanic activity.

The Northern Alxa Orogenic Belt is the southernmost segment of the Central Asian Orogenic Belt. The less investigated Shangdan pluton is a key point to understanding its tectonic evolution. The granodiorites from this pluton yield zircon LA-ICP-MS U-Pb ages of 331. 7 +/- 0. 9Ma, which is the earliest age obtained for the Late Paleozoic plutons in the Zongnaishan-Shalazhashan tectonic zone and indicates an Early Carboniferous magmatic event. The granodiorites from the Shangdan pluton have moderate silicon contents (SiO2 =66. 07% similar to 68. 15%) , high Na2O contents (Na2O/K2O > 1. 6) and relatively high CaO contents ( CaO/Na2O > 1 ) , and belong chemically to metaluminous series (A/CNK <1, A/NK > 1) with medium-K and calc-alkaline (sigma =1. 21 similar to 1. 40, K2O = 1. 55% similar to 2. 21% ) characteristics. The hornblendes are also found in the rock slices. Both the geochemistry and petrography show affinity to the I-type granites. The granodiorites have moderate REE contents and moderate to strong LREE to HREE differentiation ( (La/Yb)(N) 5. 30 similar to 6. 62). They are enriched in Rb, Th, K, Zr, Hf and depleted in Ba, Nb, Ta, P, Ti. No negative Eu anomalies have been found in the samples, suggesting that they might be derived from partial melting of middle-lower crust. Meanwhile, two whole-rock samples have slightly negative epsilon(Nd)( t) values of - 1. 02 and - 0. 91 with Nd model age t(DM1) of 1. 30 similar to 1. 28 Ga. One sample yields zircon epsilon(Hf)(t) values between +0. 30 and +5. 27 with Hf model age t(DM2) of 1. 32 similar to 1. 00Ga. Combined with geochemical analysis, the Shangdan pluton was likely recycled from the Meso-Neoproterozoic crust. In conclusion, the Shangdan pluton with arc characteristics has been discriminated to be formed in a subduction-related setting, suggesting that after the termination of the Early-Middle Paleozoic orogenesis in the northern Alxa, the Late Paleozoic subduction occurred at least in the Early Carboniferous.

An Early Paleozoic acid volcanic sequence has been recently detected southeast of Sonid Zuoqi in central Inner Mongolia to constrain the tectonic evolution of the Central Asian Orogenic Belt in this area. First, the volcanic rocks have zircon U–Pb ages of 439–445Ma. They are characterized by (a) a high silica content, moderate alkali content and low iron content; (b) enrichment in light rare earth elements, depletion of heavy rare earth elements, and negative Eu anomalies; and (c) negative Nb, Ta, and Ti anomalies. Finally, the volcanic samples yield εHf(t) values of −4.7 to +9.2 with TDM2 ages of 835–1724Ma. For petrogenesis, they were possibly arc derived, from predominant juvenile materials with subordinate ancient continental crust. Combined with previous studies, the Early Paleozoic Sonid Zuoqi arc magmatism can be divided into three stages: a primitive arc stage represented by 464–490Ma low-K, calcic granitoids; a normal continental arc stage represented by 439–445Ma medium-K, calcic to calcic-alkalic plutons and volcanic rocks and a syn-collisional stage represented by 423–424Ma high-K granites. Furthermore, the timing and tectonic settings of the above magmatic rocks show similarities to those in Xilinhot and other areas of the northern Early to Mid-Paleozoic orogenic belt (NOB), although the rock assemblies and their proportions vary more or less in different areas. Accordingly, the NOB that formed on this arc was probably attributed to the northward subduction of the Paleo-Asian Ocean beginning at ~500Ma, which experienced this type of arc development and was terminated by a soft collision before the Late Devonian.

The tectonic setting of the southeastern Central Asian Orogenic Belt (CAOB) during the Late Paleozoic has been debated for many years. Provenance analysis of Permo-Carboniferous sedimentary rocks can effectively address this issue. In this study, eight sandstone samples were collected for zircon U–Pb and Lu–Hf isotopic analyses combined with petrographic analysis. Framework petrography and zircon morphology suggest that the samples were from recycled orogen of an igneous origin. Carboniferous rocks, with a significant age peak at 432 Ma and εHf (t) values of − 9.0 to 13.6, were mainly derived from Early to Mid-Paleozoic magmatic rocks and deposited in a piedmont zone, namely, the margin of an inland sea. Permian rocks, mostly with age peaks at 445 Ma and/or 280 Ma and εHf (t) values of − 25.2 to 11.4, dominantly originated from a pre-existing Early to Mid-Paleozoic magmatic arc and Late Paleozoic igneous rocks. These rocks formed in restricted basins of the piedmont and intermountain zones. Based on zircon spectral discrimination, sedimentary environmental analysis, and previous studies, this study supports the interpretation that the southeastern CAOB entered stages of extension and rifting during the Late Paleozoic. In the end, this study proposes a tectonic-paleogeographic reconstruction to explain the tectonic evolution of the southeastern CAOB and the exhumation–transportation–deposition processes between the basins and ranges developed in this orogen.

Apatite fission track (AFT) analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0–13.2 μm) mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassic–early Cretaceous and the Oligocene–Miocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma), recording the earlier rapid uplift phase during the late Jurassic–Cretaceous, while the ages in the north piedmont of the Bogda Mountain (namely the northeast part) are younger (<60 Ma), mainly reflecting the later rapid uplift phase in the Oligocene–Miocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

The view of "small intrusions hosting large mineral deposits" scientifically summarized the features of magmatic - hydrothermal mineralizations, which has been evidenced to be an effective exploration criterion. However, why the small intrusions generally associate with large or giant mineral systems remain open to study. The author proposes that the small granitic stocks, compared to huge bath-oliths, are favorable for metal enrichment during magma generation and evolution, for fluid migration and metal transportation, and accommodating metal precipitation and accumulation.

The Qinling Orogen in central China has been a long-term geologicalyl studied focus for its unique tectonic location, complicated geological history and abundant mineral resources. In previous studies geologists have clarified its tectonic framework, outlined its geological evolution, and reached a consensus that the final transition from marine basin to intracontinental mountains occurred in Indosinian (Triassic: 251 -199.6 Ma). However, the details of basin -to -mountain transition process, the age of final oceanic closure, the nature of Triassic tectonic setting, and the associated magmatism and mineralization in the area have been poorly constrained and hotly debated. Based on a comprehensive re-assessment of results from geological, geophysical, geochemical and ore deposit studies, the author compares the Triassic Qinling with present Mediterranean Sea, which contemporaneously accommodates oceanic slab subduction and intercontinental collision as well as gradual transition from oceanic subduction to intercontinental collision. The Qinling paleo-Tethys finally closed in a westward zipper-like way during the period of 230∼200 Ma, and instantly followed by intercontinental collision between the Yangtze block and Qinling-North China united continents. Therefore, the Triassic tectonic setting in Qinling was neither a simple intercontinental collision, nor a post -orogenic or post -collisional regime. Indosinian magmatism was intensive in Qinling, forming igneous rocks including at least the adakites, cale - alkaline granitoids, high-K calc-alkaline granitoids, alkaline intrusions, Rapakivi -like granites, and carbonatites. These rocks show zoning spatial distribution, namely, northward from the Mian-Lue suture, the Yangshan - Yanzhiba peraluminous S- type granite belt, southern Qinling high-Mg and adakitic calc-alkaline granite belt, northern Qinling high-K calc-alkaline granite belt, and the carbonatite-alkaline intrusion belt at the southern margin of North China craton. Such Indosinian magmatites with distinctive petrologic complexity, lithologic diversity, spatial zonation and compositional polarity cannot be formed in syn- and/or post-collisional tectonic settings, but could have resulted from a northward paleo -Tethysan slab subduction along the Mian -Lue geosuture. Although the Indosinan mineralization has been ignored for a long time, a great number of Triassic ore deposits of economic significance have been recently discovered, including Molybdenum-containing carbonatite dykes, porphyries and orogenic-type quartz veins; orogenic-type, porphyry-/breccia pipe-type, and Carlin-type and Carlin -like gold deposits; and orogenic -type silver -dominant poly -metal deposits. This shows that mineralization of various genetic types strongly occurred in the transition regime from oceanic slab subduction to intercontinental collision, and that the Indosinian ore deposits are of exploration potential in Qinling Orogen.

The Wunugetushan porphyry Cu-Mo deposit,Inner Mongolia,occurs in the Erguna terrane which is bounded by the NE-trending Derbugan fault to the southeast.Within the Mongolia-Hinggan Orogen,the Erguna terrane evolved in the Paleozoic subduction related accretion and Early Mesozoic collision and Late Mesozoic-Cenozoic post-collision tectonics related to Pacific plate subduction.The Wunugetushan deposit,formed in Jurassic,is a typical example of porphyry ore systems developed in continental collision regime.Its geological and geochemical characteristics may be an ideal reference to understand the origin of porphyry ore- systems formed in collisional settings.This paper reports the research results on fluid inclusions obtained by microthermometric study and compositional identification using Laser Raman Spectroscope and Scanning Electron Microscope combined with Energy Spectrum. The hydrothermal ore-forming process of the Wunugetushan deposit includes three stages,i.e.the early,middle and late stages, characterized by mineral assemblages of quartz-potassic feldspar,quartz-sericite-polymetallic sulfides and illite-carbonate-quartz, respectively.In hydrothermal quartz three types of fluid inclusions can be observed.They are NaCl-H_2O solution,daughter mineral- bearing,and CO_2-rich.However,the latter two types cannot be observed in the late-stage quartz.Homogenization temperatures of fluid inclusions in early stage are above 510℃,with the highest salinities up to 75.8 wt% NaCl eqv.Fluid inclusions contain daughter minerals including halite,chalcopyrite and hematite which possibly represent an oxidizing environment.Vapor bubbles are mainly composed of CO_2,and the liquids are dominated by H_2O and generally contain CO_3~(2-).Mo and Cu are mainly mineralized in the middle stage,and in the temperature spans of 510℃～340℃ and 340℃～240℃,respectively,with fluid salinities ranging from 6.3 to 52.0 wt% NaCl eqv.In middle stage,daughter minerals in fluid inclusions,such as halite and chalcopyrite,except of hematite,can be recognized.The daughter mineral-bearng inclusions coexist with the vapor-and liquid-rich fluid inclusions.Fluid inclusions with contrasting salinities are homogenized to divergent phases at similar temperatures.These phenomena strongly suggest that fluid-boiling occurred in the middle stage.The homogenization temperatures of late stage fluid inclusions cluster into 240℃～100℃,with corresponding salinities no more than 12.4 wt% NaCl eqv.In a word,the early stage fluids are magmatic in origin and characterized by high temperature,high salinity,high oxygen-fugacity and CO_2-rich.In middle stage,the fluids boiled and resulted in CO_2-release, oxygen-fugacity decrease and rapid precipitation of ore-forming materials.The late stage fluids,characteristic of low temperature,low salinity,lack of daughter mineral and poor in CO_2,could be sourced from meteoric water.

Noble gas abundances and isotopic compositions in mantle-derived xenoliths were analyzed by crushing method, which from Keluo, Wudalianchi, Heilongjiang Province, Kuandian of Liaoning Province, Northeastern China. These results indicate the heterogeneity of subcontinental lithospheric mantle beneath northeastern China. 3 He/4 He ratios in the samples from Wudalianchi vary between 4.5 - 5.3RA, obviously lower than that of the MORB, with the signature of metasomated mantle. And their 40 Ar/36 Ar ratios change from 557 to 4005. Comparing the characteristics of noble gases with evidences from published Sr-Nd-Pb isotope data and alkali basalt petrology, it was estimated that there was a palaeo-subduction event took place in Wudalianchi area, and the upper mantle was metasomated by subducted crustic components or H2 O - CO2-rich fluid which derived from subducted slab, and coursed forming phlogopite-bearing Iherzolite. On the other hand, the samples from Kuandian show a depleted MORB-like 3 He/4 He ratio (7.30 - 7.52RA,), with 40 Ar/36 Ar ratio of 1496 - 7677. It implies that there are at least two type mantles beneath Northeastern China, the one is a metasomated subcontinental lithospheric mantle, and the other is a MORB reservoir-like mantle. They reflect different mantle evolution processes.