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The Yong'an-Meixian Late Paleozoic Hercynian depression, located in western Fujian-eastern Guangdong, is an important metallogenic belt in China. The Yushui copper-polymetallic massive sulfide deposit from the middle part of the depression, with extremely high copper grades, has attracted considerable attention and research interest from geologists for years. In most previous research, the ore-forming material source and metallogenic process were inferred from indirect evidence (i.e., using H-O-C-S isotopic systematics as geochemical tracers). In this paper, the ore-forming process of the Yushui deposit has been studied directly by using nontraditional stable (Fe–Cu) isotopes for the first time, providing new evidence for the genesis of this deposit. The results show that there is a relatively negative Fe-Cu isotopic composition in the Yushui deposit, with δ56Fe values ranging from −0.519 to −1.063‰ and δ65Cu values ranging from −1.539 to −1.609‰, respectively. The fractionation of Fe isotopes is primarily attributed to hydrothermal leaching of the basement strata by ore-forming fluids, along with rapid precipitation of sulfides during the ore-forming process. On the other hand, the fractionation of Cu isotopes is probably controlled by the relatively low temperature of ore formation, sulfide precipitation and the involvement of organic matter in mineralization. Combining our findings with previous studies, the ore-forming materials of the Yushui deposit are likely derived from the basement ore-bearing strata (pre-Devonian strata) through leaching by hydrothermal fluids. Moreover, some of the ore bodies might have been locally overprinted by late-stage hydrothermal reworking and alteration. [ABSTRACT FROM AUTHOR]

Controversy over the geodynamic interpretation of the early Paleozoic granites in the South China Block constrains understanding of tectonic–magmatic evolution. In this paper, we present zircon U-Pb age, Hf isotope, and major and trace element data of the early Paleozoic granites in the Jilongjie region, south-central Hunan Province. A sample that yielded a weighted average 206Pb/238U age of 425 ± 3 Ma falls into the post-collisional granite field in the classification discriminant of magmatic rocks. Geochemical features indicate that the Jilongjie pluton is a shoshonitic metaluminous rock. The Jilongjie pluton's chondrite-normalized rare earth element patterns exhibit a slight enrichment of light rare earth elements (LREEs) relative to heavy rare earth elements (HREEs) with (La/Yb)N ratios of 15.1–23.7 and weak Eu anomalies (Eu/Eu* = 0.68–0.78). Zircon Hf isotope results show εHf(t) ranging from −9.94 to −0.69. Jilongjie granite's parent magma originated from a mixing of crust-derived felsic and mantle-derived mafic magmas, which then underwent fractional crystallization during its ascent. Jilongjie granite was generated through a post-collisional extensional setting associated with delamination of the thickened lithosphere. [ABSTRACT FROM AUTHOR]

On the basis of elaborating on the regional geological background, this paper analyzes the lithological and sedimentary characteristics and explorative prospects of new strata with oil and gas in the southern and surrounding areas of Dayangshu Basin. Based on the latest high-precision airborne gravity and magnetic comprehensive survey data, combined with the latest data from geological explorations, physical surveys, and drilling, and the use of basin structure layering combination methods, we clarified the characteristics of the bottom of the Jurassic–Cretaceous and the occurrence characteristics of the Upper Paleozoic in the study area and revealed the determinative effect of multi-period structures on the most important sedimentary layers. Then, we summarized the accumulation conditions and prediction methods of hydrocarbons and proposed the oil and gas prospects of these deep new strata. The results show that the Liuhe Sag in Dayangshu Basin, the depression in the northeast of Longjiang Basin, and the northern parts of the Taikang swell have good source–reservoir–cap combination conditions and favorable structural characteristics for oil and gas, where there is a high potential for exploration. [ABSTRACT FROM AUTHOR]

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

The Truong Son orogenic belt (TSOB) is one of the most important orogenic belts in the Indochina block. There are numerous mafic to felsic intrusions in the Early Paleozoic caused by the Tethyan orogeny. However, the tectono-magmatic evolution of the TSOB in the Early Paleozoic is still unclear. In this paper, zircon U-Pb dating, whole-rock geochemistry, and the Sr-Nd isotopic data of the Early Paleozoic magmatic rocks have been systematically investigated to explore the petrogenesis and tectonic significance of these rocks in the TSOB. Based on our new results integrated with previous geological data, four major tectono-magmatic episodes are identified. (1) The Middle Cambrian (~507 Ma) is the early stage of northward subduction of the Tamky-Phuoc Son Ocean. (2) The Early Ordovician to Middle Ordovician (483–461 Ma) is the main subduction stage of the Tamky-Phuoc Son Ocean. The intrusive rock associations imply the closure of the Tamky-Phuoc Son Ocean. (3) The Late Ordovician to Early Silurian (461–438 Ma) is the collision stage of the Kontum massif and Truong Son terrane. (4) The Early Silurian to Late Silurian (438–410 Ma) is the late stage of collision accompanied by slab roll-back. [ABSTRACT FROM AUTHOR]

A comprehensive assessment of the critical elements contained in coal is essential for understanding the geological processes that affect the enrichment of these elements, which can then be used to fully utilize coal in an economically and environmentally friendly manner. In order to understand the geology of an area and the impact of demolition rock on the formation and enrichment of trace elements, as well as rare earth elements (REE) in coals, we have presented a range of recent geochemical and mineralogical data from the k7 coal seam in the Karaganda Formation of the Karaganda Coal Basin. The study revealed that the geochemical characteristics of coal-bearing deposits in the Karaganda Basin reflect the features of its geological evolution. Despite high tectonic activity and volcanic activity in the Paleozoic era, the specific composition of the rocks on the slopes and bases of coal-bearing valleys has determined the low potential for rare metals in the basin. It has been found that the coal in the Karaganda Basin is, in general, similar in terms of concentrations of most trace elements to the average for world coal. The main area of provenance of the trace elements was established using discriminant diagrams. It was established that the main source of the trace elements, including REEs in the basin coals, was the Tekturmas accretionary complex that represented the main upland (anticlinorium) during the coals' formation. SEM studies identified micro-mineral forms that indicated the presence of trace elements of Zr, Ti, Se, and Fe in the samples of stratum k7. [ABSTRACT FROM AUTHOR]

The Longshou Shan, located in western China, plays a crucial role in connecting the Tarim Continent with the North China Craton. It provides valuable insights into the Cenozoic intracontinental deformation, the complex dynamics of Eurasian tectonics, and the relationship between the pre-Cenozoic Tethys and Central Asian orogenic systems. Consequently, comprehending the evolution of the Phanerozoic era in this region holds immense significance. Zircon (U-Th)/He (ZHe) dating was conducted on three granite samples (n = 18) collected from the Longshou Shan. The ZHe dates of these granite rocks range from 7.2 to 517.7 Ma, showing a negative correlation with eU values. Furthermore, a limestone sample from the Longshou Shan yielded ZHe (n = 4) ages of 172.0–277.1 Ma and AHe (n = 4) ages of 17–111.9 Ma. The area has undergone complex tectonic processes involving multiple phases of uplift and burial. Using both forward and inverse modeling methods, we aim to establish plausible thermal histories. Our models reveal: (1) Late Paleozoic unroofing; (2) Early Mesozoic cooling and Late Mesozoic regional stabilization; and (3) Cenozoic reheating and subsequent cooling. By investigating the intricate thermal history of the Longshou Shan through multi-method modeling, we compare different approaches and assess the capabilities of single ZHe dating for understanding a thermal history. This research contributes to unraveling the region's geological complexities and aids in evaluating various modeling methods. [ABSTRACT FROM AUTHOR]

The properties of the Caledonian orogeny along the transition belt of the Yangtze and Cathaysia blocks have received much attention in recent years. The widespread Early Paleozoic granites provide critical geological clues for unraveling the tectonic evolution and geodynamic processes of the South China Continent (SCC). Here we present new zircon U–Pb chronology, whole-rock major and trace elements, in situ Hf isotopes for Paleozoic granites, i.e., the Wugongshan granites in the northwest Jiangxi province, and aim to explore the magmatism and properties of the Caledonian orogeny involved in their formation. Our new data show that the Wugongshan granites were emplaced during the Early Silurian Period (442–438 Ma). The Paleozoic Wugongshan granites belong to S-type muscovite-bearing peraluminous granites (MPG) and show a single origin. The Wugongshan granites exhibit negative εHf(t) values (−11.56 to −6.19) and TDM2 model ages of 2148–1809 Ma, indicating their derivation from an ancient crustal source, through partial melting of ancient crustal material. The Wugongshan granitic magmatism is probably being generated in an extensional environment related to an intracontinental orogeny setting. It is inferred that the Paleozoic tectonic–magmatic event in the Wugongshan area was associated with the oceanic–continental convergence of the Paleo-Tethys Ocean. The Wugongshan granites highlight the intracontinental magmatism in the Early Paleozoic orogeny in the SCC. [ABSTRACT FROM AUTHOR]

The Qinling Complex is located in the core of the northern Qinling Orogen and plays a key role in understanding the tectonic evolution of the Qinling Orogen, but its metamorphic evolution remains controversial. The combined investigation of petrographic observation, zircon U-Pb dating, and phase equilibria modeling for garnet amphibolites from the Tianshui area in the West Qinling Orogen is reported in this study. The results show that the garnet amphibolites record a clockwise P-T path characterized by a pre-TMax decompression heating stage, a temperature peak at P-T conditions of 0.84–0.99 GPa and 869–886 °C, followed by a decompression cooling stage. Zircon U-Pb dating yields four age populations of ~479 ± 4 Ma, ~451 ± 8 Ma, ~411 ± 4 Ma, and ~377 ± 6 Ma. The 479–450 Ma reflects the timing of the pre-TMax high–medium pressure upper amphibolite-facies metamorphism. The metamorphism at peak temperature condition occurred at c.411 Ma and was followed by decompression cooling to c.377 Ma. The Ordovician high–medium pressure metamorphism is related to the continental collision, which is slightly later than the HP–UHP eclogite-facies metamorphism in the East Qinling Orogen. The HT granulite-facies metamorphism at peak temperature condition took place at reduced pressures, suggesting thinning of the collision-thickened orogenic crust. Therefore, the northern West Qinling Orogen experienced a tectonothermal evolution from initial crust thickening to thinning during the Paleozoic collisional orogeny. [ABSTRACT FROM AUTHOR]

The Devonian–Carboniferous boundary is one of the most important turning points in geological history, marked by the Late Paleozoic Ice Age and Late Devonian extinction. This study investigates the carbon isotope stratigraphy across the Devonian–Carboniferous boundary in Lhasa block, Tibet, China, which was part of the Gondwana continent during that time. The carbon isotope curves show a significant negative excursion trend, consistent with those of the South China block and other regions on the Laurentia continent. This global negative shift may be attributed to the burial of significant amounts of 12C-rich organic matter in strata, a consequence of the Late Devonian extinction event. Based on the carbon isotope curve and stratigraphic data of the Lhasa block, this study determined, for the first time, the specific horizon of the Devonian–Carboniferous boundary in Tibet, which is located between grayish white bioclastic limestone and yellowish-brown sandy limestone in the upper part of the Chaguoluoma Formation (D1C1ĉ). These findings provide a new reference for the international stratigraphic community to reconsider the position of GSSP on the Devonian–Carboniferous boundary, as well as study the Late Devonian mass extinction and Late Paleozoic glaciation. [ABSTRACT FROM AUTHOR]

The closure timing of the Paleo-Asian Ocean and the terminal stage of the Central Asian Orogenic Belt have been widely debated in the geological community. It's known that the gradual scissor-like closure of the Paleo-Asian Ocean occurred from west to east during the Paleozoic period. However, it was not until the Triassic period that the complete closure of the ocean occurred at the northeastern margin of the North China Craton. Nevertheless, there is still much uncertainty regarding the Late Triassic tectonic setting in Northeast China. In this study, we focused on the Upper Triassic Dajianggang Formation, located in the Shuangyang area of central Jilin Province, which is situated on the northeastern margin of the North China Plate. Our aim was to determine the formation age of the Dajianggang Formation by analyzing the detrital particle composition, petrogeochemistry, detrital zircon U-Pb isotope dating, and apatite fission track thermochronology. Our results indicated that the primary sandstone provenance area of the Dajianggang Formation in the Shuangyang area is the island arc orogenic belt. The tectonic background of the sandstone provenance area is mainly a continental island arc environment. The provenance area is mostly composed of felsic rocks with sedimentary tendencies, and some of its material may have originated from the northern margin of the North China Craton or the eroded recycle orogenic belt. LA-ICP-MS U-Pb dating of detrital zircons shows that the Dajianggang Formation formed after 226.8 ± 5 Ma. Moreover, analysis of the thermal evolution history modelling shows that the Dajianggang Formation in the Shuangyang area continued to be deposited and heated in the early stage, and then experienced rapid exhumation around 30 Ma. This suggests that the study area underwent an orogenic process during the early stage of formation, but then transitioned into a post-orogenic extension period, which constrained the final closure of the Paleo-Asian Ocean prior to the Late Triassic period. In addition, our study indicates that the remote effect of the Pacific subduction did not reach the study area until 30 Ma. The central age of the detrital apatite fission track of sample 19DJ-1 is 94.2 ± 8.3 Ma, which is younger than its corresponding stratigraphic age. The two peak ages of the fission track analysis are 62.9 ± 5.4 Ma and 126 ± 11 Ma. These findings provide new evidence for the tectonic evolution of Northeast China and shed light on the Late Triassic tectonic setting, as well as the influence time of subsequent tectonic domains in the southern part of Northeast China. [ABSTRACT FROM AUTHOR]

The formation and evolution of the ancient continental crust are crucial issues in solid-earth geology which are commonly associated with global tectonic events and the formation of economically valuable magmatic-hydrothermal ore deposits. The Cathaysia Block, one of the ancient continents in Southeast Asia, can be subdivided into two parts: the West Cathaysia Block and the East Cathaysia Block. Unlike the East Cathaysia Block, no Precambrian rocks are exposed in the West Cathaysia Block, constraining further understanding of the formation and evolution of this block. In this study, a total of four hundred and thirty-three zircon U-Pb dating analyses and two hundred and eighteen Lu-Hf isotopic analyses on zircon grains from the Jurassic Dengfuxian granites and Ordovician Tanghu granites, Nanling Range, were carried out. LA-ICP-MS zircon U-Pb dating yields mean average 206Pb/238U ages of 152.6 ± 2.2 Ma (MSWD = 1.6) and 442.4 ± 1.7 Ma (MSWD = 3.8), which are regarded as the rock-forming age for the Jurassic Dengfuxian granites and Ordovician Tanghu granites, respectively. The 207Pb/206Pb ages of the inherited zircons from the Jurassic Dengfuxian granites and Ordovician Tanghu granites range from 522 Ma to 3395 Ma, hosting two major peaks at the 0.9–1.0 Ga and 2.4–2.5 Ga. In contrast to the East Cathaysia Block, the West Cathaysia Block lacks the age peak of 1.8–1.9 Ga, indicating that the West Cathaysia Block was not influenced by the assembly of the Columbia supercontinent in the Paleo-Proterozoic. In combination with the Lu-Hf isotopes, we proposed that the crust evolution of the West Cathaysia Block in Archean is dominated by juvenile crustal growth events, and dominated by the crustal reworking since the Proterozoic. The long duration of crustal reworking in the West Cathaysia Block resulted in the enrichment of lithophile elements (e.g., W, Sn, Nb, and Ta) in the crust of that region. Therefore, the Jurassic granites in the Nanling Range, which are mainly derived from the partial melting of Proterozoic basement rocks, became associated with large-scale tungsten polymetallic mineralization. [ABSTRACT FROM AUTHOR]

Copper mineralization in the Lower Paleozoic sedimentary cover of the Anti-Atlas (Morocco) is continually being revised not only to improve its mining capacity, but also to determine its origin, which remains a matter of debate. As evidenced by the various models proposed, the related research is fragmented, localized, and confusing. The origin of the Anti-Atlas Lower Paleozoic copper mineralization is shared between synergistic and epigenetic processes or a superposition of the two processes. Based on new tectono-magmatic data and a reinterpretation of the ore structural arrangement, we propose a link between the last concentration of copper deposits and the Late Triassic–Early Liassic CAMP (Central Atlantic Magmatic Province) tectono-thermal event, as evidenced by the significant concentration of copper mineralization in the three NE–SW corridors affected by extensional faults, some of which are filled with dolerite CAMP magma. The heat flow generated by the mafic dykes within these reactivated corridors causes mineralized fluids to up well into the sedimentary layers, depositing material rich in juvenile or leached copper, or even a mixture of the two. In some cases, these fluids are trapped by fracture systems that accompany passive folds initiated on normal faults. In other cases, these fluids can infiltrate bedding planes, and even karst caves, formed during carbonate exhumation. Notably, extensive NE–SW faults systematically cover the early Hercynian structures, suggesting that they belong to a post-Hercynian extensional episode. During the Late Triassic, the global fragmentation of the Pangaea supercontinent was manifested by the stretching of the continental crust at the margin of northwest Africa, with the simultaneous opening of the Central Atlantic Ocean and emplacement of CAMP magmatism. This last and often overlooked tectonothermal event must be considered in the remobilization and reconcentration of copper mineralization and other mineralization in Morocco. [ABSTRACT FROM AUTHOR]

The Bogda Range (hereafter referred to as the Bogda) is located in the Eastern Tianshan. Interpreting its tectono-thermal history is critical to understanding the intra-continental evolution of the Tianshan. In this study, we report new apatite fission track data from the late Paleozoic–Mesozoic sedimentary rocks in the northern Bogda and the Late Paleozoic granites in the southern Bogda to investigate the exhumation history of the Bogda. Apatite fission track ages dominantly range from the Jurassic to earliest Cenozoic (~143–61 Ma), except for one siliciclastic sample from the Early Permian strata with an older age of ~251 Ma. Thermal history modeling, together with detrital apatite fission track age peaks, reveal that the Bogda underwent three episodes of cooling during the Late Triassic, the Late Cretaceous, and the Late Miocene. The Late Triassic rapid cooling may represent the initial building of the Bogda, which is probably related to the final closure of the Paleo-Asian Ocean. During the Late Cretaceous, the Bogda may have experienced a moderate exhumation, which was possibly triggered by the extensive tectonic extension in the central–eastern Asian regime during the Cretaceous. The Late Miocene rapid cooling may be a response to the rapid uplift of the whole Tianshan, due to the far-field effect of the continuous India–Eurasia collision since the beginning of the Cenozoic. [ABSTRACT FROM AUTHOR]

The northward subduction of the Paleo-Tethys oceanic crust in the Paleozoic to Mesozoic is critical for the tectonic evolution of the Qinling-Tongbai-Hong'an-Dabie-Sulu-Imjingang-Gyeonggi orogenic belt. However, the Paleozoic geological fingerprint of the Paleo-Tethys oceanic crust subduction in the Dabie-Sulu orogenic belt remains obscure. In the present study, apatite from the Muniushan monzogranite in the Houkuang area was analyzed to constrain the age of metamorphism in the Jiaobei Terrane and is regarded as the response to the Paleo-Tethys oceanic crust subduction in the Early Permian. Muniushan apatite with obvious negative Eu anomaly is enriched in LREE and depleted in HREE. The chondrite-normalized REE patterns of apatite correspond with I-type granitoids and mafic igneous rocks, implying a magmatic origin. Igneous apatite grains have reset compositional zonation in the cathodoluminescence image. Apatites plotted on a support vector machine apatite classification biplot and Eu/Y-Ce discrimination diagram shows a tendency from the region of "mafic igneous rocks and I-type granitoids" to "low and middle metamorphic". This evidence consistently suggests that the Muniushan apatite suffered metamorphism at a later stage. The twenty-six apatite grains from the Muniushan monzogranite yield a metamorphic age of 297 ± 8 Ma (by LA-ICP-MS U-Pb), which is different from the Muniushan zircon SHRIMP U-Pb results of 2110 ± 4 Ma, indicating the metamorphism occurred in the Early Permian and reset the U-Pb system of apatite. The Early Permian metamorphism that occurred in the Jiaobei Terrane is synchronous to the subduction of the Paleo-Tethys oceanic crust and is the response to the Paleo-Tethys oceanic crust subduction. [ABSTRACT FROM AUTHOR]

The Taoxi dome stands out as a rotated-circular structure on maps of the Wuyi terrane, south China. The origin and tectonic activity analysis of the Taoxi dome is a window to understand the tectonic framework and aggregation process of the Wuyi terranes in the Cathaysia block. Our field observations demonstrated that two major phases of deformation, counterclockwise rotation and dome uplift, were recorded in the Taoxi dome. Geochronological data indicated that the counterclockwise rotation was initiated at about 422 Ma as a result of a sinistral slide collision between the North Wuyi terrane and the South Wuyi terrane along the Nanping–Ninghua tectonic belt during the Caledonian. Zircon dating ages of the intrusions developed in the Taoxi dome suggested that the Taoxi dome had undergone at least two strong upheavals and the uplift of the Taoxi dome was active during the periods 229–222 Ma and 158–100 Ma. Geochemical data indicated that the intrusions developed in the Taoxi dome had characteristics of high silica (SiO2 > 70 wt.%) and belonged to the A2-type granites, which suggest that the Taoxi dome was long governed by a tectonic setting of post-collisional or anorogenic magmatism since the Caledonian. The strong movement of the Caledonian rotation and coeval strike-slip movement in the Wuyi terranes suggests that a slide rotation may have been a major characteristic in response to the rifting process of micro-terranes during the late Paleozoic in the Cathaysia block. [ABSTRACT FROM AUTHOR]

The evolution of the eastern Paleo-Asian Ocean (PAO) has controlled the formation of the southeastern Central Asian Orogenic Belt (CAOB). However, the evolution history and final closure time of the eastern PAO still remain controversial, which greatly restricts understanding of the formation process of the CAOB. To address these issues, we provide detailed zircon chronology and Hf isotope and geochemical data of Paleozoic to Triassic magmatic rocks in the southeastern CAOB. We have identified four periods of magmatism as evidenced by: Early Silurian quartz diorites (434.7 Ma), Early Devonian monzogranites (394.2 Ma), Middle Permian granites (260.2–264.5 Ma) and Late Permian-Early Triassic syenogranite (250.8–253.6 Ma). These rocks have features of low MgO and mantle-compatible elements, are enriched in Th, U, K, Pb, Sr, Zr and Hf and depleted in Nb, Ta, La, Ce, P, and Ti. The quartz diorites belong to the medium-K calc-alkaline series with εHf(t) values of −0.76 to 2.21, indicating that they may be derived from partial melting of mafic lower crust with minor contribution of mantle magma. The monzogranites and syenogranite have high Zr + Nb + Ce + Y (260–390; 261–461 ppm, respectively), total alkali contents (9.98–10.80; 8.46–9.29 wt.%, respectively), and high zircon saturation temperature (807–840; 810–885 °C). They can be classified as A-type granites. Monzogranites have εHf(t) values (between −1.20 and +3.34); hence, we believe that they were derived from the crust modified by mantle-derived fluids or melts. Syenogranite have high εHf(t) values (5.49–11.36), and we suggest that they were derived from the juvenile lower crust that originated from the depleted mantle. The granites have high Sr/Y ratios (118–257), low Y (1.42–2.82 ppm), and Yb (0.31–0.41 ppm), consistent with the features of adakite. Considering the εHf(t) isotopic values (2.99–8.50), we suggest that they originated from thickened juvenile lower crust. Combining the results from our own and previous studies, we propose a new evolution model of the eastern PAO from Paleozoic to Triassic. It can be divided into two stages: (1) Late Cambrian to Early Devonian; (2) Early Permian to Triassic. The first stage is the evolution of the Bainaimiao ocean (secondary ocean basin of the PAO), which closed in the Late Silurian and led to the Bainaimiao arc accretion to the North China Cratons. The second stage is the final closure of the eastern PAO during the Late Permian (~254 Ma). [ABSTRACT FROM AUTHOR]

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

The Li-bearing pegmatites of the Pampean Pegmatite Province (PPP) occur in a rare-element pegmatite belt developed mainly in the Lower Paleozoic age on the southwestern margin of Gondwana. The pegmatites show Li, Rb, Nb ≤ Ta, Be, P, B, Bi enrichment, and belong to the Li-Cs-Ta (LCT) petrogenetic family, Rare-Element-Li (REL-Li) subclass; most of them are of complex type and spodumene subtype, some are of albite-spodumene type, and a few of petalite subtype. The origin of the pegmatites is attributed predominantly to fractionation of fertile S-type granitic melts produced by either fluid-absent or fluid-assisted anatexis of a thick pile of Gondwana-derived turbiditic sediments. Most of the pegmatites are orogenic (530–440 Ma) and developed during two overlapped collisional orogenies (Pampean and Famatinian); a few are postorogenic (~370 Ma), related to crustal contaminated A-type granites. The pegmatites were likely intruded in the hinterland, preferably in medium-grade metamorphic rocks with PT conditions ~200–500 MPa and 400–650 °C, where they are concentrated in districts and groups. Known combined resources add up 200,000 t of spodumene, with variable grades between 5 and 8 wt.% Li2O. The potential for future findings and enlargement of the resources is high, since no systematic exploration program has yet been developed. [ABSTRACT FROM AUTHOR]

Magmatic rocks, deformed structures, and tin–polymetallic deposits are widely distributed in the western Jiangnan Orogenic Belt (JOB) of northern Guangxi Province, China. Magmatism and mineralization are believed to have occurred in the Neoproterozoic stage. Herein, we report the zircon U–Pb dating results of investigations on the Ping'an Pb–Zn–Cu polymetallic veins hosted in gabbro near Ping'an Village. Zircon U–Pb dating of the host gabbro yielded ages of 853.0 ± 7.8, 837.7 ± 7.2, and 450.4 ± 6.7 Ma. The younger age represents the emplacement of gabbros, whereas the older Neoproterozoic age reflects inherited zircons from the wall rocks or source regions. The formation of gabbros (Caledonian) is related to the subduction and collisions of microplates in the western JOB, which are controlled by movements of the Yangtze and Cathaysian plates. We consider that the late Caledonian regional shearing in the western JOB resulted in the fracturing and faulting of rocks (Neoproterozoic and early Caledonian), which provided conduits for the flow of hydrothermal fluids and accommodation for the associated mineralization. Geochemistry investigations show that the Caledonian basic magmatic activity provided a certain material source for the final mineralization. We propose that the tin–polymetallic deposits in the northern Guangx Province, and Neoproterozoic cassiterite crystallization, were subjected to Caledonian shear crushing and hydrothermal transformation with copper, lead, zinc, and other metal elements based on our comprehensive analysis, providing a new ideology for understanding the geology and mineralization in this area. [ABSTRACT FROM AUTHOR]

Lower Paleozoic black shales from Estonia, Sweden, and Russia were analyzed for major and trace elements to reconstruct the provenance, tectonic setting, and paleoweathering conditions of these shales. The black shale is highly enriched in U, V, Mo, and Pb (except in samples from Sweden where Pb is slightly enriched), slightly enriched in SiO2, Fe2O3, K2O, and TiO2 and highly depleted in CaO, Na2O, and MnO, with respect to average shales. The provenance signatures (Th/Sc versus Zr/Sc, Al2O3 versus TiO2, Zr versus TiO2 plots, and Zr/Sc ratio) of the Baltoscandian black shales suggest that they were derived from rocks of intermediate to felsic composition and from recycled sediments. The likely provenance region was the Paleoproterozoic igneous and metamorphic basement of southern central and southern Finland, which consists predominantly of felsic to intermediate metamorphic (acidic to intermediate gneisses, felsic volcanics, microcline granites and migmatites) and igneous rocks (small granitic intrusions and large rapakivi granite intrusions), and reworked older Ediacaran and Lower Cambrian sediments; however, the proportion of clastic input from these sources is not uniform in the three regions studied. The discrimination of the tectonic settings of source materials of the black shale using the SiO2 versus K2O/Na2O plot and a new discriminant method (APMdisc) favors a passive margin setting. The Chemical Index of Weathering (CIW) indicates that the clastic material in the black shale of the studied regions has experienced an intense degree of chemical weathering. Weathering indices (Chemical Index of Alteration CIA and CIW) also show that the black shale has experienced significant secondary potassium enrichment. [ABSTRACT FROM AUTHOR]

The Tianshui-Sunjiaxia area is located in the connection zone of West Qinling Orogen and North Qilian Orogen, which could provide great insights into the amalgamation processes between the northern and southern blocks of China. Three subduction- and rift-related rocks gneissic granite from North Qilian arc-interarc belt (NQAI) granite and metabasalt from North Qinling back-arc basin (NQBA) are distinguished across the connection zone. The gneissic granite was generated by melts from older crustal materials of Longshan Group with the addition of a relatively juvenile basaltic source from the lower crust during the collision process. The Liwanxincun metabasalt reflects the mixing of the partial melting of the shallow asthenospheric mantle and the metasomatized mantle in a back-arc extension setting. The LA-ICP-MS zircon U-Pb dating of gneissic granite (068, 069) yields crystallization ages of 457.0 ± 1.6 Ma and 445.9 ± 2.1 Ma. The study area is divided into six tectonic units in Early Paleozoic time involving NQAI (Yanjiadian-Xinjie) continental arc, interarc rift basin (Maojiamo-Xiwali), continental arc (Chenjiahe-Wangjiacha); NQBA back-arc rift basin (Huluhe-Hongtubao), island arc and ophiolitic melange belt (North Qinling-Shangdan). A tectonic model is proposed in which the NQAI continental arc (Yanjiadian-Xinjie) might represent the early period of subduction of North Qilian Ocean (NQO) and the interarc rift is the product of the extension triggered by southward subduction of NQO. The ongoing subduction of NQO then leads to the formation of Chenjiahe-Wangjiacha continental arc, as well as the Hongtubao back-arc spreading ridge in NQBA back-arc basin (Huluhe). The tectonic evolution of the connection zone is closely associated with the closure of the North Qilian Ocean and North Qinling-Shangdan Ocean in the context of the convergence process of micro-continental blocks, including North China block, Longshan group and North Qinling Terrane. [ABSTRACT FROM AUTHOR]

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

The TTZ-South seismic profile follows the Teisseyre-Tornquist zone (TTZ) at the SW margin of the East European craton (EEC). Investigation results reveal the upper lithospheric structure as representing the NW-vergent, NE-SW striking overthrust-type, Paleoproterozoic (~1.84–1.8 Ga) Fennoscandia-Sarmatia suture. The Sarmatian segment of the EEC comprises two crustal-scale tectonic thrust slices: the Moldavo-Podolian and Lublino-Volhynian basement units, overriding the northerly located Lysogoro-Radomian unit of Fennoscandian affinity. The combined results of the TTZ-South and other nearby deep seismic profiles are consistent with a continuation of the EEC cratonic basement across the TTZ to the SW and its plunging into the deep substratum of the adjacent Paleozoic platform. Extensional deformation responsible for the formation of the mid to late Proterozoic (~1.4–0.6 Ga), SW-NE trending Orsha-Volhynia rift basin is probably also recorded. The thick Ediacaran succession deposited in the rift was later tectonically thickened due to Variscan deformation. The Moho depth varies between 37 and 49 km, resulting in the thinnest crust in the SE, sharp depth changes across the TTZ, and slow shallowing from 49 to 43 km to the NW. The abrupt Moho depth increase from 43 to 49 km is considered to reflect the overlying lower crust tectonic duplication within the suture zone. [ABSTRACT FROM AUTHOR]

This study discussed the pertrological classification, geochronology, petrogenesis and tectonic evolution of early Paleozoic granites from the Xingshuping gold deposit in the East Qinling orogenic belt. In order to achieve this target, we carried out an integrated study of zircon U–Pb age, whole-rock major and trace elements, as well as Sr–Nd–Hf isotope compositions for the Xingshuping granites (part of the Wuduoshan pluton) from the Erlangping unit. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating constrains the emplacement age of the Xingshuping granites at 446.2 ± 1.2 Ma. The rocks at Xingshuping can be divided into two types: mainly biotite granite and monzonitic granite. The biotite granites are typical adakitic rocks, while the monzonitic granites show characteristics similar to normal arc volcanic rocks. The geochemical compositions reveal that they were derived from a clay-rich, plagioclase-rich and biotite-rich psammitic lower continental crust source, with contributions of mantle-derived magmas. The distinction is that the biotite granites were primarily derived from partial melting in a syn-collision extension setting, whereas the monzonitic granite went through a fractional crystallization process in an intraplate anorogenic setting. [ABSTRACT FROM AUTHOR]

Pre-Mesozoic exotic crystalline blocks within the Outer Carpathian flysch have potential to unravel the nature of their eroded basement source(s) and to reconstruct the Paleozoic–Precambrian history of the Protocarpathians. Strongly tectonized Campanian–Maastrichtian grey marls in the Subsilesian Nappe of the Outer Western Carpathians in Poland contain a variety of different lithology types, including granitoids and andesites. Petrological investigations coupled with zircon and apatite U-Pb dating were performed on crystalline (subvolcanic) exotic blocks from a locality in the Subsilesian Nappe. U-Pb zircon dating yields magmatic crystallization ages of c. 293 Ma for the microgranitoid and c. 310 Ma for the andesite block, with inherited zircon cores yielding Archean, Paleoproterozoic, Mesoproterozoic and Cadomian ages. Whole rock trace element and Nd isotope data imply that the melt source was composed of a significant Neoproterozoic crustal component in both the microgranite and andesite. The Late Carboniferous–Permian magmatic activity likely continues outside the Carpathian Belt and can be linked to a Late Paleozoic transtensional zone, which is a continuation of the Lubliniec–Kraków Zone that extends under the Carpathians to Moesia. This Late Paleozoic transtensional zone was probably reactivated during the Late Cretaceous under a transpressional regime within the Żegocina tectonic zone, which caused the uplift of the Subsilesian Ridge and intensive erosion. [ABSTRACT FROM AUTHOR]

Pegmatite-type uranium mineralization occurs in the Shangdan domain of the North Qinling Orogenic Belt, representing a significant uraniferous province. The Guangshigou deposit is the largest U deposit of the district. Within the North Qinling area, a series of Caledonian granitic igneous rocks intruded the Proterozoic metamorphic rocks of the Qinling Group in two magmatic stages: (i) the Early Silurian Huichizi granite that was derived from a low degree of partial melting of thickened lower basaltic crust combined with mantle-derived materials following the subduction of the Shangdan Ocean; and (ii) the Late Silurian–Early Devonian Damaogou granite and associated pegmatites derived from the same source but emplaced in a late tectonic post-collisional extension environment. In the Guangshigou deposit, the U mineralization mainly occurs as uraninite disseminated in U-rich granitic biotite pegmatites, which formed by assimilation-fractional crystallization magmatic processes. Petrographic observations showed evidence for coeval crystallization of uraninite and other rock-forming minerals of the host pegmatite including quartz, feldspar, biotite, zircon, monazite, apatite, and xenotime. In addition, the low U/Th ratios (~19) and Th, REE, and Y enrichments characterized a magmatic origin for uraninite, which was likely derived from fractionated high-K calc-alkaline pegmatitic magma that experienced various degrees of crustal material contamination. In situ U-Pb isotopic dating performed by Secondary-Ion Mass Spectrometry (SIMS) on uraninite from the Guangshigou deposit yielded a crystallization age of 412 ± 3 Ma, which is concomitant (within errors) with the emplacement age of the host pegmatite (415 ± 2 Ma) and constrained the U ore genesis to the Early Devonian, which corresponds to the late Caledonian post-collisional extension in the North Qinling area. Uraninite then experienced various degrees of metamictization and/or post-Caledonian hydrothermal alteration characterized by an alteration rim associated with coffinite, chlorite and limonite. Finally, the characteristics of the pegmatite-related Guangshigou deposit exhibiting Th-rich uraninite which was the product of assimilation-fractional crystallization of pegmatitic magma defined a model significantly different than the one established for the world-class Rössing deposit characterized by Th-poor uraninite hosted in alaskite dykes formed by low degree of partial melting of U-rich metasediments. [ABSTRACT FROM AUTHOR]

Ultra-high pressure (UHP) metamorphism is recorded by garnet clinopyroxenite enclaves enclosed in an undeformed, unmetamorphosed granitic pluton, northeastern Paleozoic Dunhuang orogenic belt, northwestern China. The protoliths of the garnet clinopyroxenite might be basic or ultrabasic volcanic rocks. Three to four stages of metamorphic mineral assemblages have been found in the garnet clinopyroxenite, and clockwise metamorphic pressure–temperature (P-T) paths were retrieved, indicative of metamorphism in a subduction environment. Peak metamorphic P-T conditions (790–920 °C/28–41 kbar) of garnet clinopyroxenite suggest they experienced UHP metamorphism in the coesite- or diamond-stability field. The UHP metamorphic event is also confirmed by the occurrence of high-Al titanite enclosed in the garnet, along with at least three groups of aligned rutile lamellae exsolved from the garnet. Secondary ion mass spectrometry (SIMS) U-Pb dating of metamorphic titanite indicates that the post-peak, subsequent tectonic exhumation of the UHP rocks occurred in the Devonian period (~389–370 Ma). These data suggest that part of the Paleozoic Dunhuang orogenic belt experienced UHP metamorphism, and diverse metamorphic facies series prevailed in this Paleozoic orogen. It can be further inferred that most of the UHP rocks in this orogen remain buried. [ABSTRACT FROM AUTHOR]