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Rieske-type non-heme iron oxygenases/oxidases catalyze a wide range of transformations. Their applications in bioremediation or biocatalysis face two key barriers: the need of expensive NAD(P)H as a reductant and a proper reductase to mediate the electron transfer from NAD(P)H to the oxygenases. To bypass the need of both the reductase and NAD(P)H, using Rieske-type oxygenase (Stc2) catalyzed oxidative demethylation as the model system, we report Stc2 photocatalysis using eosin Y/sulfite as the photosensitizer/sacrificial reagent pair. In a flow-chemistry setting to separate the photo-reduction half-reaction and oxidation half-reaction, Stc2 photo-biocatalysis outperforms the Stc2-NAD(P)H-reductase (GbcB) system. In addition, in a few other selected Rieske enzymes (NdmA, CntA, and GbcA), and a flavin-dependent enzyme (iodotyrosine deiodinase, IYD), the eosin Y/sodium sulfite photo-reduction pair could also serve as the NAD(P)H-reductase surrogate to support catalysis, which implies the potential applicability of this photo-reduction system to other redox enzymes.

FtmOx1 is a nonheme iron (NHFe) endoperoxidase, catalyzing three disparate reactions, endoperoxidation, alcohol dehydrogenation, and dealkylation, under in vitro conditions; the diversity complicates its mechanistic studies. In this study, we use two substrate analogues to simplify the FtmOx1-catalyzed reaction to either a dealkylation or an alcohol dehydrogenation reaction for structure-function relationship analysis to address two key FtmOx1 mechanistic questions: (1) Y224 flipping in the proposed COX-like model vs α-ketoglutarate (αKG) rotation proposed in the CarC-like mechanistic model and (2) the involvement of a Y224 radical (COX-like model) or a Y68 radical (CarC-like model) in FtmOx1-catalysis. When 13-oxo-fumitremorgin B (

Plastic materials are ubiquitous in medical devices and consumer goods. As bacterial contamination of plastic surfaces can pose significant health risks, there is a need for effective approaches both to inactivate bacteria on plastic surfaces and to prevent colonization of plastic surfaces. In this study, we evaluate a plasmonic photoreactor coating for plastic surfaces that provides both active and passive antimicrobial effects and implement a visible light-driven antibacterial flow sterilizer. We demonstrate that this approach inactivates bacteria in an aqueous suspension passed through a photoreactor-coated polyethylene tubing, achieving log reduction values (LRVs) > 5 for both Gram-positive and -negative bacteria under resonant LED illumination. Importantly, the antimicrobial flow sterilizers do not cause a detectable loss of functionality for monoclonal antibodies that were included in this work as an example of high-value biologics that require sterilization. Under ambient light illumination, the plasmonic photoreactor coating exhibits a significant inhibitory effect on bacterial colonization and biofilm formation. The inhibitory effect was substantially weaker for mammalian cells, indicating some selectivity in the protection provided by the coating.

Modulation of OvoAMtht's dual activities: sulfoxide synthase and thiol oxygenase.

In 2019, a serious dengue virus (DENV) infection broke out in the Xishuangbanna Dai Autonomous Prefecture, China. Therefore, we conducted a molecular epidemiological analysis in people that contracted DENV serotype 1 (DENV-1) during this year. We analyzed the molecular epidemiology of six DENV-1 epidemic strains in 2019 by full-length genome sequencing, amino acid mutation site analysis, evolutionary tree analysis, and recombination site comparison analysis. Through the analysis of amino acid mutation sites, it was found that DENV-1 strain (MW386867) was different from the other five epidemic DENV-1 strains in Xishuangbanna in 2019. MW386867 had unique mutation sites at six loci. The six epidemic DENV-1 strains in Xishuangbanna in 2019 were divided into two clusters. MW386867 was highly similar to the MG679800 (Myanmar 2017), MG679801 (Myanmar 2017), and KC172834 (Laos 2008), and the other five strains were highly similar to JQ045660 (Vietnam 2011), FJ176780 (GuangDong 2006). Genetic recombination analysis revealed that there was no recombination signal in the six epidemic DENV-1 strains in Xishuangbanna in 2019. We speculate that the DENV-1 epidemic in 2019 has a co-epidemic of local strains and cross-border strains.

The Sulu ultrahigh-pressure (UHP) belt has been proven to form by deep northward subduction of the Yangtze Block (YB) beneath the North China Block (NCB) in the Triassic. The basement rocks origina...

Ergothioneine, a natural longevity vitamin and antioxidant, is a thiol-histidine derivative. Recently, two types of biosynthetic pathways were reported. In the aerobic ergothioneine biosynthesis, a non-heme iron enzyme incorporates a sulfoxide to an sp(2) C-H bond in trimethyl-histidine (hercynine) through oxidation reactions. In contrast, in the anaerobic ergothioneine biosynthetic pathway in a green sulfur bacterium, Chlorobium limicola, a rhodanese domain containing protein (EanB) directly replaces this unreactive hercynine C-H bond with a C-S bond. Herein, we demonstrate that polysulfide (HSS(n)SR) is the direct sulfur-source in EanB-catalysis. After identifying EanB’s substrates, X-ray crystallography of several intermediate states along with mass spectrometry results provide additional mechanistic details for this reaction. Further, quantum mechanics/molecular mechanics (QM/MM) calculations reveal that protonation of N(π) of hercynine by Tyr353 with the assistance of Thr414 is a key activation step for the hercynine sp(2) C-H bond in this trans-sulfuration reaction.

Dengue fever was included in the top 10 global health threats announced by the World Health Organization (WHO) in early 2019. In some southern provinces of China, autochthonous outbreaks have also been reported over the last decade. An unexpected large outbreak of dengue fever was reported in Xishuangbanna, a border area of China, Myanmar, and Laos, in 2019. Among the 226 hospitalized cases, 90 were diagnosed as severe dengue according to the 2009 WHO guidelines. Serotyping and phylogenetic analyses of envelope gene sequences from 246 randomly selected samples showed that three serotypes of dengue virus were co-circulating in this outbreak, which is very rare in this area. Dengue virus serotype 1 (DENV-1, genotype I) and serotype 2 (DENV-2, Cosmopolitan genotype and Asian genotype) were the main pathogenic agents of this outbreak. Dengue virus serotype 3 (DENV-3) epidemic strains were classified as genotype III and formed a close cluster with the Thailand 2015 epidemic strain. The co-circulation may have led to more serious clinical symptoms and a larger scale epidemic. This finding is of great importance in understanding the circulation of DENV and to strengthen the detection and management of dengue fever in border areas.

In the anaerobic ergothioneine biosynthetic pathway, a rhodanese domain containing enzyme (EanB) activates tne hercynine’s sp(2) ε-C-H Dona ana replaces it with a C-S bond to produce ergothioneine. The key intermediate for this trans-sulfuration reaction is the Cys412 persulfide. Substitution of the EanB-Cys412 persulfide with a Cys412 perselenide does not yield the selenium analog of ergothioneine, selenoneine. However, in deuterated buffer, the perselenide-modified EanB catalyzes the deuterium exchange between hercynine’s sp(2) ε-C-H bond and D(2)O. Results from QM/MM calculations suggest that the reaction involves a carbene intermediate and that Tyr353 plays a key role. We hypothesize that modulating the pK(a) of Tyr353 will affect the deuterium-exchange rate. Indeed, the 3,5-difluoro tyrosine containing EanB catalyzes the deuterium exchange reaction with k(ex) of ~10-fold greater than the wild-type EanB (EanB(WT)). With regards to potential mechanisms, these results support the involvement of a carbene intermediate in EanB-catalysis, rendering EanB as one of the few carbene-intermediate involving enzymatic systems.

Mononuclear non-heme iron enzymes are a large class of enzymes catalyzing a wide-range of reactions. In this work, we report that a non-heme iron enzyme in

To better understand the formation of high-temperature metamorphic rocks, we present a detailed petrological and geochronological study of recently discovered cordierite-bearing granulites of the South Liaohe Group in the Jiao-Liao-Ji Belt, North China Craton. Petrographic observations indicate that four distinct mineral assemblages are present in the granulites: pre-peak amphibolite facies (M1), peak granulite facies (M2), post-peak decompression (M3), and late cooling retrogression (M4). M1 is preserved as fine-grained inclusions in the cores of garnet grains, represented by quartz + plagioclase + biotite + ilmenite. M2 is interpreted to have comprised garnet + sillimanite + plagioclase + quartz + biotite + ilmenite + melt. M3 was characterized by the formation of cordierite + sillimanite symplectites and cordierite + quartz coronas replacing garnet. M4 is indicated by the formation of staurolite, accompanied by the crystallization of melt. A combination of multi-equilibria geothermobarometers and pseudosection modeling constrains the P–T conditions of the M1, M2, M3, and M4 stages to P = 0.66–0.71 GPa and T = 620–650 °C, P = 0.96–1.10 GPa and T = 790–840 °C, P = 0.62–0.65 GPa and T = 725–785 °C, and P = 0.43–0.55 GPa and T = 595–625 °C, respectively. Zircon and monazite U–Pb dating yields three distinct and meaningful ages for the granulites: (1) 2200–2100 Ma for the granulite protoliths, (2) ca. 1945 Ma for the near-peak metamorphism, and (3) 1851–1839 Ma for the post-peak and late retrogressive metamorphism. Thus, a clockwise P–T–t path is determined for the cordierite-bearing granulites of the South Liaohe Group. Petrological and geochronological evidence from regional metamorphic rocks in the Jiao-Liao-Ji Belt suggests that the belt experienced a continuous orogenesis from 1950 to 1800 Ma.

In the southern zone of the Paleoproterozoic Jiao-Liao-Ji Belt (JLJB), North China Craton (NCC), abundant granitic leucosomes are widespread within migmatites as irregular layers, lenses, and blocks. They are parallel to or as cross-cut foliations in the host rocks on various scales, and show distinct evidence of migmatization in the formation of these centimeter- to decimeter-scale segregations. The migmatites extend at least 1100 km in length, spreading over the whole JLJB, from the Ji’an Group in south Jilin, through the South Liaohe Group in Liaodong Peninsula, to the Jingshan Group in Jiaodong Peninsula, rather than as sporadic outcrops limited to the Jiaobei Terrane as reported in previous studies. The granitic leucosomes are comprised mainly of quartz, K-feldspar, and antiperthitic plagioclase (albite), with secondary minerals of garnet, biotite, zircon, etc. They are enriched in SiO 2 (74.65–75.54 wt%), Al 2 O 3 (13.25–14.87 wt%), and K 2 O + Na 2 O (8.19–8.95 wt%), but have a lower TiO 2 + Fe 2 O 3 + FeO + MgO + MnO content (0.42–1.34 wt%). The major element components are similar to those of granitic leucosomes of pelitic granulites in typical orogenic belts around the world. A combined study of whole-rock geochemistry, mineral inclusions, cathodoluminescence (CL) images, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dates of zircons revealed the nature and timing of partial melting of the host pelitic granulites. All dated anatectic zircons from various granitic leucosomes display magmatic zones with distinct cores and rims, and contain mineral inclusions of Qtz + Kfs + Ab ± Ap in both domains. Both the cores and rims exhibit unusually high U and Th contents, and anomalously low Th/U ratios (

The Eastern Block of the North China Craton records Paleoproterozoic oceanic plate subduction, the opening and subsequent closure of a back-arc basin, and a following collisional orogenic e...

Chinese civilization has always been called "rites and music civilization"(li-yue-wen-ming ). It is also the due meaning of sacred education to educate the people and change customs with rites and music. Chinese sage education aims to cultivate benevolent gentlemen with five constant virtues, which are based on benevolence, and this benevolence is embodied in the civilization of rites and music in Chinese society. It is precisely because of "the substance and function relationship"(ti-yong-guan-xi ) between benevolence and "the system of rites and music"(li-yue-zhi-du ) that Zhu Zi's Xiao Xue education pays particular attention to cultivating gentlemen with ideal personality through rites and music education.

The X-ray crystal structures of FtmOx1, the first known α-ketoglutarate-dependent mononuclear non-haem iron enzyme that can catalyse an endoperoxide formation reaction, are presented, along with further biochemical analyses which reveal the catalytic versatility of mononuclear non-haem iron enzymes, and help to unravel the mechanisms of endoperoxide biosyntheses. Verruculogen, a non-ribosomal peptide produced by various Aspergillus and Penicillium strains, contains an unusual and highly reactive endoperoxide (R-O-O-R) functional group that is generated from fumitremorgin B by the mononuclear non-haem iron enzyme FtmOx1. Pinghua Liu and colleagues report the X-ray crystal structures of FtmOx1 alone and in the presence of fumitremorgen B or α-ketoglutarate. Together with further biochemical analyses, these structures reveal the catalytic versatility of mononuclear non-haem iron enzymes, and help to unravel the mechanisms of endoperoxide biosyntheses. Verruculogen, a non-ribosomal peptide produced by various Aspergillus and Penicillium strains, contains an unusual and highly reactive endoperoxide (R-O-O-R) functional group that is generated from fumitremorgin B by the mononuclear non-haem iron enzyme FtmOx1. Pinghua Liu and colleagues report the X-ray crystal structures of FtmOx1 alone and in the presence of fumitremorgen B or α-ketoglutarate. Together with further biochemical analyses, these structures reveal the catalytic versatility of mononuclear non-haem iron enzymes, and help to unravel the mechanisms of endoperoxide biosyntheses. Many peroxy-containing secondary metabolites1,2 have been isolated and shown to provide beneficial effects to human health3,4,5. Yet, the mechanisms of most endoperoxide biosyntheses are not well understood. Although endoperoxides have been suggested as key reaction intermediates in several cases6,7,8, the only well-characterized endoperoxide biosynthetic enzyme is prostaglandin H synthase, a haem-containing enzyme9. Fumitremorgin B endoperoxidase (FtmOx1) from Aspergillus fumigatus is the first reported α-ketoglutarate-dependent mononuclear non-haem iron enzyme that can catalyse an endoperoxide formation reaction10,11,12. To elucidate the mechanistic details for this unique chemical transformation, we report the X-ray crystal structures of FtmOx1 and the binary complexes it forms with either the co-substrate (α-ketoglutarate) or the substrate (fumitremorgin B). Uniquely, after α-ketoglutarate has bound to the mononuclear iron centre in a bidentate fashion, the remaining open site for oxygen binding and activation is shielded from the substrate or the solvent by a tyrosine residue (Y224). Upon replacing Y224 with alanine or phenylalanine, the FtmOx1 catalysis diverts from endoperoxide formation to the more commonly observed hydroxylation. Subsequent characterizations by a combination of stopped-flow optical absorption spectroscopy and freeze-quench electron paramagnetic resonance spectroscopy support the presence of transient radical species in FtmOx1 catalysis. Our results help to unravel the novel mechanism for this endoperoxide formation reaction.

Poly-metamorphism has been observed in many Precambrian metamorphic terranes. The metamorphic overprinting in the poly-metamorphic rocks makes it difficult to determine the timing and P − T path of each metamorphic event. In this study, in situ U–Pb dating of zircon, xenotime, and monazite, with simultaneously determination of trace element compositions, is utilized to provide new constraints on the timing of discrete metamorphic events involving reactivation of the Jiao-Liao-Ji Belt, the eastern edge of the North China Craton. Detrital zircons from metasandstones in the Gaixian Formation record a mixed provenance that includes late Neoarchean (ca. 2532 Ma) and middle Paleoproterozoic (ca. 2181 Ma). Xenotimes from the Gaixian pelitic schists yield an upper intercept age of 1906 ± 25 Ma, and this age is interpreted as the timing of greenschist-facies regional metamorphism. However, monazites from the same pelitic schists yield a distinctly younger age of 242 Ma, with late Paleoproterozoic inherited ages of 1894 and 1809 Ma, which are broadly consistent with the xenotime ages. In addition, magmatic zircons from a granitic mylonite vein yield a similar age of 245 Ma, making it coeval with the monazite. The interpretation of these ages is also reinforced by the mineral assemblage of inclusions in the dated accessory mineral grains. These new geochronological data, combined with published data from the Jiao-Liao-Ji Belt and the related regions, suggest that the Gaixian Formation in the Yanghe area was likely some time deposited at 2181–1900 Ma, and experienced both late Paleoproterozoic and Triassic low-grade metamorphic events related to two distinct orogenic phases in the eastern North China Craton.

Protein chemical modifications are important tools for elucidating chemical and biological functions of proteins. Several strategies have been developed to implement these modifications, including enzymatic tailoring reactions, unnatural amino acid incorporation using the expanded genetic codes, and recognition-driven transformations. These technologies have been applied in metalloenzyme studies, specifically in dissecting their mechanisms, improving their enzymatic activities, and creating artificial enzymes with non-natural activities. Herein, we summarize some of the recent efforts in these areas with an emphasis on a few metalloenzyme case studies.

A dengue virus serotype 1 (DENV-1) epidemic occurred from October to December 2018 in Xishuangbanna, Yunnan, Southwest China, neighboring Myanmar, Laos, and Vietnam. In this study, we investigated the molecular characteristics, evolution, and potential source of DENV from Xishuangbanna. The C (capsid), prM (premembrane), and E (envelope) genes of DENV isolated from 87 serum samples obtained from local patients were amplified and sequenced, and the sequences were evaluated by identification of mutations, phylogenetic and homologous recombination analysis, and secondary structure prediction. Phylogenetic analysis showed that all of the epidemic DENV strains from Xishuangbanna could be grouped in a branch with DENV-1 isolates, and were most similar to the Fujian 2005 (China, DQ193572) and Singapore 2016 (MF314188) strains. When compared with DENV-1SS (the standard strain), there were 31 non-synonymous mutations, but no obvious homologous recombination signal was found. Secondary structure prediction showed that some changes had occurred in a helical region in proteins of the MN123849 and MN123854 strains, but there were few changes in the disordered region. This study reveals the molecular characteristics of the structural genes of the Xishuangbanna epidemic strains in 2018 and provides a reference for molecular epidemiology, infection, and pathogenicity research and vaccine development.

Blueschists are sporadically exposed as lenses within the Lancangjiang metamorphic complex, and represent unique components of the Paleo-Tethys. In this paper, we present geochemical and geochronological results of blueschists to decipher their origin and tectonic significance. The whole-rock geochemical analyses revealed strong similarities with ocean island basalt (OIB), and further discrimination diagrams confirm an affinity to a within-plate setting. Combined studies on blueschists using cathodoluminescence (CL) imaging, SHRIMP U-Pb dating of zircon domains and 40Ar/39Ar dating of phengite and glaucophane provide evidence of their magmatic origin and metamorphic evolution. Slightly oscillatory zoned or compositionally homogeneous zircon grains/domains, as well as structureless zircon rims, yield ages from 231.6 ± 3.7 to 225.3 ± 4.8 Ma, recording the blueschist facies metamorphic event. In contrast, the captured zircon grains and cores with a major age peak at ~241 Ma as well as several minor older age peaks indicate the multiple provenance of the zircons. 40Ar/39Ar step heating analyses on single grains of phengite and glaucophane separated from blueschists yield plateau ages ranging from 242.5 ± 1.4 to 228.7 ± 1.5 Ma which are interpreted to reflect high-pressure metamorphism. This study provides geochemical and geochronological constraints on the tectonic evolution of the Paleo-Tethyan ocean, which was closed and subsequently subducted as a result of the collision of the Simao and Baoshan Blocks. During subduction in Trassic (243 to 225 Ma), the protoliths of blueschists underwent blueschist facies conditions.

Ergothioneine is a thiohistidine derivative with potential benefits on many aging-related diseases. The central step of aerobic ergothioneine biosynthesis is the oxidative C–S bond formation reaction catalyzed by mononuclear nonheme iron sulfoxide synthases (EgtB and Egt1). Thus far, only the Mycobacterium thermoresistibile EgtB (EgtB(Mth)) crystal structure is available, while the structural information for the more industrially attractive Egt1 enzyme is not. Herein, we reported the crystal structure of the ergothioneine sulfoxide synthase (EgtB(Cth)) from Candidatus Chloracidobacterium thermophilum. EgtB(Cth) has both EgtB- and Egt1-type of activities. Guided by the structural information, we conducted Rosetta Enzyme Design calculations, and we biochemically demonstrated that EgtB(Cth) can be engineered more toward Egt1-type of activity. This study provides information regarding the factors governing the substrate selectivity in Egt1- and EgtB-catalysis and lays the groundwork for future sulfoxide synthase engineering toward the development of an effective ergothioneine process through a synthetic biology approach.

Ovothiols are thiol-histidines that play important roles in protecting cells against oxidative stresses. Because of challenges faced in their chemical synthesis, biosynthesis provides an alternative option. In ovothiol biosynthesis, a nonheme iron enzyme (OvoA) catalyzes a four-electron oxidative coupling between l-His and l-Cys. There are debates in the literature over whether oxidative C–S bond formation or sulfur oxidation is the first half of OvoA-catalysis. In this report, by incorporating a tyrosine analogue, 2-amino-3-(4-hydroxy-3-(methoxyl) phenyl) propanoic acid (MeOTyr), via an amber-suppressor method, we modulated the rate-limiting steps of OvoA-catalysis and observed an inverse deuterium KIE for [U-2H5]-His. In conjunction with the reported quantum mechanics/molecular mechanics (QM/MM) studies, our results suggest that Y417 plays redox roles in OvoA-catalysis and imply that oxidative C–S bond formation is most likely the first half of the OvoA-catalysis.

The Paleoproterozoic Jiao-Liao-Ji Belt (JLJB) in the North China Craton, a major terrane boundary, has remained controversial with respect to its tectonic history. Here we report LA–ICP–MS U–Pb zircon ages, and whole-rock elemental and isotopic compositions of mafic rocks intruding into the North and South Liaohe Groups, with the aim of evaluating their petrogenetic affinities and metamorphic history, and their implications for the tectonic evolution of the JLJB. The mafic rocks in the North Liaohe Group dominantly composed of meta-diabase and meta-gabbro, whereas mafic rocks in the South Liaohe Group are mainly (garnet-) amphibolite. LA–ICP–MS zircon U–Pb analyses yield crystallization and metamorphic ages of ca. 2130 Ma and ca. 1880 Ma, respectively, suggesting that they are coeval, and were metamorphosed at the same time. Whole-rock elemental and isotopic compositions suggest tholeiitic affinity for the protoliths of both of them, with variable SiO2 and MgO concentrations and Mg# and eNd(t) values. They both display enriched mid-oceanic-ridge basalt (E-MORB)-like trace element patterns with enrichment in light rare earth elements and depletion in some high field strength elements (HFSEs; e.g., Nb, Ta, and Ti). The data suggest derivation of the melts from a depleted asthenospheric mantle, coupled with fractional crystallization and crustal contamination. Some of the mafic rocks in the South Liaohe Group have lower HFSE (e.g., Nb, Ta, Zr, Hf, and Ti) concentrations, and La/Sm and Th/La ratios, and higher U/Th ratios than their counterparts in the North Liaohe Group, possibly suggesting enhanced metasomatism by subduction-related fluids and/or melts. The geochemical features of the mafic rocks from JLJB contrast with those of typical intra-continental rifts and volcanic arcs, and may have formed in a back-arc basin. Our study supports the presence of a ca. 2.2–2.1 Ga back-arc basin that formed due to northward subduction and subsequent closure of an oceanic plate, resulting in arc–continent collision and formation of the JLJB at ca. 1.9 Ga.

The ultrahigh-pressure (UHP) eclogite and country rocks of the North Sulu UHP metamorphic belt have traditionally been considered the products of the deep subduction of the Yangtze Block (YB) beneath the North China Block (NCB). However, widely distributed non-UHP meta-mafic rocks, appearing as irregular lenses and thin layers together with UHP eclogite in the Haiyangsuo-Wuji-Weihai area along the northwestern margin of the North Sulu UHP belt, prompted investigation of the petrogenetic diversity and complex tectonic evolution of these rocks. The UHP index mineral assemblage of garnet + omphacite + rutile ± phengite ± coesite is common in the matrix of UHP and retrograde eclogites, or as inclusions preserved in metamorphic zircons indicating UHP metamorphism. In contrast with previous studies, herein high-pressure and medium-pressure (HP–MP) granulite facies index mineral assemblage of garnet + clinopyroxene + plagioclase + quartz ± orthopyroxene + ilmenite was commonly identified in the matrix of non-UHP mafic granulites and amphibolites, indicating that these rocks underwent HP–MP granulite facies metamorphism rather than UHP metamorphism. The whole-rock geochemical data revealed multiple origins for the UHP and retrograde eclogites with protoliths derived from heterogeneous mantle or lower–upper crust sources with weak fractional crystallization. In contrast, the protolith of the non-UHP meta-mafic rocks may have derived from a depleted or primitive mantle origin source with varying degrees of crustal contamination during emplacement. The UHP and retrograde eclogites exhibited Neoproterozoic (803–760 Ma) protolith ages and underwent UHP eclogite facies metamorphism in the Middle Triassic (233–225 Ma) with subsequent Late Triassic (219–210 Ma) amphibolite facies retrogression. In contrast, the non-UHP meta-mafic rocks exhibited older Paleoproterozoic (>1944 Ma) protolith ages. The two distinct metamorphic events that occurred in the Paleoproterozoic (1944–1825 Ma) and Middle–Late Triassic (226–201 Ma) are related to the Paleoproterozoic Jiao-Liao-Ji orogeny and the Triassic collisional event between the YB and NCB, respectively. A combined study of petrography, whole-rock geochemistry and zircon U–Pb ages revealed that the UHP and retrograde eclogites show a close affinity to the Neoproterozoic continental crust on the northern margin of YB, whereas the non-UHP meta-mafic rocks show a close affinity to the Paleoproterozoic Jiaobei Terrane. Both the UHP and non-UHP meta-mafic rocks, together with their country rocks form an approximately 200 km long melange zone rather than a single UHP belt, which extends from the Haiyangsuo through the Wuji to the Weihai area along the northwestern margin of the North Sulu UHP belt.

The Jiao-Liao-Ji Belt is located between the Longgang and Langrim blocks in the Eastern Block of the North China Craton (NCC). The belt comprises Palaeoproterozoic volcanic–sedimentary successions that are divided into the Ji’an, South Liaohe, and Jingshan groups in the south and the Laoling, North Liaohe and Fenzishan groups in the north. The tectonic setting and depositional environments of the Liao-Ji area are debated. This paper presents geochemical and detrital zircon U-Pb data for the boron-bearing, graphite-bearing, aluminum-rich Ji’an Group and the clastic sediments and carbonates of the Laoling Group in southern Jilin Province, in order to constrain their depositional ages, provenance and tectonic setting. Zircon geochronology for both the Ji’an and Laoling groups yields age peaks of 2.57–2.41, 2.23–2.09, and 2.04–2.02 Ga, indicating that the sediments were derived from the Longgang and/or Liaonan block(s), the 2.2–2.1 Ga Liaoji granitoids and ∼2.0 Ga igneous rocks, respectively. On the basis of the youngest detrital zircons and the oldest metamorphic zircon peaks, depositional ages can be constrained to the period of 2.13–1.94, 2.10–1.94, and 1.95–1.90 Ga for the Mayihe, Huangchagou, and Dadongcha formations of the Ji’an Group, and 2.18–1.90, 2.08–1.91, 1.99–1.90, 1.96–1.90, and 1.94–1.90 Ga for the Dataishan, Zhenzhumen, Huashan, Linjiang, and Dalizi formations of the Laoling Group, respectively. The zircon age spectra of each formation indicate that deposition of the Ji’an and Laoling groups was related to the opening and closing of a back-arc during the period 2.2–1.9 Ga. The Dataishan Formation (Laoling Group) was deposited in the rift environment during opening of the back-arc. During the early stage, the Mayihe and Huangchagou formations (Ji’an Group) were deposited on the side of the magmatic arc, and the Zhenzhumen Formation (Laoling Group) was deposited on the passive-margin side. During the late stage, both Ji’an and Laoling groups were deposited in a pre-orogenic setting, including the Dadongcha, Huashan, Linjiang and Dalizi formations. Detrital zircon age spectra of the Ji’an Group are similar to those of the South Liaohe Group (with the exception of the Gaojiayu Formation), indicating that the two groups had a similar provenance.

Iron(II)- and α-ketoglutarate-dependent (Fe/αKG) enzymes catalyze a large array of reactions. Although hydroxylation reaction catalyzed by these enzymes has been investigated in great details, invo...

As one of the most ancient cratons in Asia, the North China Craton (NCC) provides an opportunity to examine the evolution of the early earth. However, it is poorly known about the tectonic setting of the Eastern Block of the NCC at 2.47–2.17 Ga. In this study, zircon U-Pb dating was conducted to constrain the provenance, depositional age, and depositional environment of the Langzishan Formation in the Liaodong peninsula, to investigate the tectonic setting of the Eastern Block during the earliest Paleoproterozoic. Provenance analysis suggests that the basal sandstones (protolith of quartzite) in the Langzishan Formation were sourced from 3.8 to 2.5 Ga continental crust, while the overlying sandstone and pelite units were sourced exclusively from 2.5 Ga continental crust. The distribution of detrital zircon ages shows that the basal sandstones of the Langzishan Formation were deposited at 2.47–2.2 Ga, during which the tectonic setting changed from an early collisional setting (2.47–2.35 Ga) to a stable continental margin (2.35–2.2 Ga), whereas pelites in the upper layer of the Langzihsan Formation were deposited at 2.2–2.17 Ga, and also experienced a transition in tectonic setting from a passive continental margin to an active continental margin. The Langzishan Formation is believed to be the lowest sedimentary unit in the Eastern Block. The transition of tectonic setting of this formation shows that the Eastern Block probably has undergone the same transition at 2.47–2.17 Ga, from a collisional setting to a passive continental margin, and then to an active continental margin, possibly related to both onset of the 2.3–2.2 Ga Paleoproterozoic tectono-magmatic lull (TML) and its cessation.

The Liaohe Group is an important Paleoproterozoic lithostratigraphic unit of the Jiao-Liao-Ji orogenic belt and traditionally subdivided into the North and South Liaohe Groups. However, their tectonic setting and evolution are still a matter of debate. The precise depositional and metamorphic data of the studied metasedimentary rocks from the South Liaohe Group provide important information on the controversial discussion of the tectonic setting and evolution. Based on cathodoluminescence (CL) imaging and connecting LA-ICP-MS U-Pb geochronology, zircon grains separated from metasedimentary rocks of different formations of the South Liaohe Group were subdivided into detrital and metamorphic zircons or zircon domains. Igneous zircon cores of detrital zircons of the Li’eryu, Gaojiayu, Dashiqiao and Gaixian Formations yield U-Pb age peaks at ∼2130 Ma, ∼2520 Ma, ∼2160 Ma/∼2500 Ma, and ∼2040 Ma, indicating that their sediments were transported from the Liaoji Granitoids, the Archean basement rocks of the adjacent Complex. In addition, deposition age of the sedimentary precursors was investigated which must have taken place at some time after ∼2.05 Ga, ∼2.07 Ga, ∼2.04 Ga and ∼1.92 Ga, respectively. These new geochronological data can be well explained by (1) a continent-arc collision model which suggests that the South Liaohe Group formed an intervening island arc and foreland basin sandwiched between the Longgang and Nangrim Complexes, and (2) a northward subduction of the Nangrim Complex source rocks of the South Liaohe Group; these source rocks were successively deposited along the margin of the two Complexes.

A combined study of zircon U-Pb ages, Lu-Hf isotopes and whole-rock geochemistry was carried out for representative charnockites from the Yishui terrane in the Western Shandong Province, NCC. The results demonstrate that the charnockites in the Yishui terrane are of igneous origin rather than derivation from remelting or metamorphism of supracrustal rocks. Zircon U-Pb dating for the charnockites in the Yishui terrane indicates protolith emplacement around 2.52–2.56 Ga and synchronous metamorphism around 2.50–2.53 Ga. Zircon Lu-Hf isotopes analyses show that the charnockites have positive e Hf(t) values with an average +4.03, and depleted mantle two-stage zircon Hf model ages (T DM2 ) mainly cluster around 2.7–3.0 Ga, indicative of a source of juvenile crust formed around 2.7–3.0 Ga. Furthermore, the charnockites with 2 tend to be magnesian calcic to calc-alkalic and metaluminous, only a small population of the charnockites with >70 wt% SiO 2 are ferroan alkali-calcic and weakly peraluminous, which are consistent with geochemical features of Cordilleran-type granitoids, suggesting a deeply eroded magmatic arc derived from remelting of juvenile crust mainly formed around 2.7–3.0 Ga. Taken the comprehensives of available whole-rock geochemical and Zircon Lu-Hf isotopic data of the charnockites, synchronous emplacement and metamorphism, high-temperature setting of charnockites, granulite-facies metamorphism of anticlockwise P-T path in the Yishui terrane as well as the whole NCC, we conclude that the combined geodynamics of mantle plume and oceanic crust subduction might contribute to the formation of the charnockites in the Yishui terrane as well as similar late Archean charnockites in other areas of the NCC, further implying extensive occurrences of modern-style plate tectonic accretions in late Archean in the NCC.

The Paleoproterozoic Jiao-Liao-Ji Orogenic Belt in the eastern North China Craton provides evidence of the evolution from the early rifting and ocean opening to the final collision of the Longgang and Nangrim blocks. However, it is still open to debate, and thus controversial, as to whether the Jiao-Liao-Ji Orogenic Belt formed by closure of a rift without subduction or from an ocean with subduction. Based on detailed field mapping and structural analysis on a micro/meso-scale of the Liaohe Group in the center of the Orogenic Belt, we define at least four phases of deformation and metamorphism. S 0 is bedding formed during deposition of the lower Liaohe sediments in the Liaohe back-arc basin. During D 1 deformation an early greenschist facies event (M 1 ) was associated with a bedding-parallel S 1 metamorphic foliation, penetrative axial planar foliation, micro- to meso-scale folds (F 1 ), and an L 1 lineation, all formed during accretion, probably in a trench-subduction setting. An M 2 metamorphism took place during medium-pressure Barrovian-type amphibolite facies conditions and associated D 2 deformation that gave rise to major thrusts, open-isoclinal folds and a well-developed crenulation cleavage during exhumation of high-pressure and high-temperature rocks and collision of the Longgang and Nangrim blocks. M 3 metamorphism at sillimanite (M 3 1 ) and cordierite (M 3 2 ) grade was associated with D 3 deformation that produced regional gentle re-folds related to post-collisional exhumation of the Orogenic Belt. An M 4 retrograde metamorphism and D 4 deformation gave rise to a weak foliation that can be correlated with late Cretaceous extension that affected the whole eastern North China Craton. We present new isotopic ages (LA-ICPMS U-Pb zircon) of a granitic vein (2162 Ma), a pegmatite (1840 Ma), and a very late granite (114 Ma) that are integrated with relevant published data. Accordingly, the formation age of deformation and metamorphism was set up, and at last, a modified tectonic model was presented.

High-pressure (HP) mafic granulites in the Pingdu–Anqiu area of the Jiaobei Terrane, in the southwestern segment of the Jiao–Liao–Ji Belt of the North China Craton, occur as irregular lenses or deformed dike swarms within the Paleoproterozoic graphite-bearing paragneisses and marbles. Petrographic examination has revealed three distinct metamorphic mineral assemblages: a peak HP granulite-facies assemblage (M1) that consists of garnet + clinopyroxene + plagioclase + quartz ± amphibole ± Fe–Ti oxides, a post-peak decompression assemblage (M2) that is characterized by symplectites of orthopyroxene + clinopyroxene + plagioclase ± amphibole ± Fe–Ti oxides, and a late cooling assemblage (M3) represented by symplectites of amphibole + plagioclase + Fe–Ti oxides. Pseudosection modeling using THERMOCALC in the NCFMASHTO system and conventional thermobarometers constrained the P–T conditions of the M1, M2 and M3 assemblages to P = 1.28–1.44 GPa and T = 757–805 °C, P = 0.50–0.80 GPa and T = 780–840 °C, and P = 0.55–0.73 GPa and T = 665–730 °C, respectively. An integrated study involving laser Raman spectroscopy and scanning electron microscope analysis of mineral inclusions, cathodoluminescence imaging, and in-situ U–Pb dating of zircons showed that the protolith ages of the HP mafic granulites are mainly 2200–2000 Ma and that the timing of the peak HP granulite-facies metamorphism ranges from 1950 to 1900 Ma, as recorded by the cores of metamorphic zircons. The medium- to low-pressure amphibolite- to granulite-facies retrogression occurred mainly at 1900–1800 Ma, as recorded by the rims of some zircon grains as well as zircon grains that contain inclusions of clinopyroxene + orthopyroxene + plagioclase + amphibole + sphene. Comprehensive petrographic, mineralogical, and geochronological investigations of the HP mafic granulites defined a clockwise P–T–t path involving near-isothermal decompression and near-isobaric cooling, which further suggests that the Jiaobei Terrane had underwent initial crustal thickening during 1950–1900 Ma, followed by relatively rapid exhumation, cooling, and retrogression in the period 1900–1800 Ma. This P–T–t path was probably generated by the Paleoproterozoic collisional orogenesis of the North China Craton.

High-pressure (HP) mafic granulites in the Daqingshan–Wulashan Complex from the central segment of the Khondalite Belt of the North China Craton occur as irregular lenses or deformed dike swarms within dioritic–granitic gneisses and meta-sedimentary rocks. The HP mafic granulites contain three distinct mineral assemblages: a peak HP granulite-facies assemblage (M1) that consists of garnet + clinopyroxene + plagioclase + amphibole ± quartz ± Fe–Ti oxides; a post-peak decompression assemblage (M2) that is characterized by symplectites of orthopyroxene + clinopyroxene + plagioclase ± amphibole ± Fe–Ti oxides; a late cooling assemblage (M3) represented by symplectites of amphibole + plagioclase + Fe–Ti oxides. Pseudosection modeling using THERMOCALC in the NCFMASHTO system and conventional thermobarometers constrain the P–T conditions of the M1, M2, and M3 assemblages to P = 1.25–1.40 GPa and T = 760–815 °C, P = 0.72–0.80 GPa and T = 825–860 °C, and P = 0.69–0.81 GPa and T = 645–730 °C, respectively. In-situ U–Pb dating of zircons show that the protolith ages of the HP mafic granulites are 2100–2000 Ma and the timing of peak HP granulite-facies metamorphism is 1960–1940 Ma. The medium- to low-pressure amphibolite- to granulite-facies retrogression occurred mainly from 1920 to 1820 Ma. Petrographic investigations, mineral compositions, metamorphic reaction histories, P–T calculations, and geochronological data define a clockwise P–T–t path involving near-isothermal decompression and near-isobaric cooling, which suggests that the Daqingshan–Wulashan Complex underwent initial crustal thickening from 1960 to 1940 Ma, followed by relatively rapid exhumation, cooling, and retrogression from 1920 to 1820 Ma. This P–T–t path was likely the result of the Paleoproterozoic continental–continental (or arc) collision during the amalgamation of the North China Craton.

The Ji’an area in the Jiao–Liao–Ji Belt of the North China Craton is characterized by granulite-facies metamorphic rocks, including orthopyroxene–cordierite–garnet pelitic granulites and clinopyroxene–orthopyroxene mafic granulites. The pelitic granulites contain orthopyroxene, cordierite, garnet, biotite, and feldspar, whereas the mafic granulites contain coarse-grained orthopyroxene, clinopyroxene, amphibole, biotite, plagioclase, and quartz. Petrographic observations, traditional thermobarometry, and quantitative phase equilibria modeling of the pelitic granulites reveal a clockwise P–T path involving near-isothermal decompression and decompressional cooling that followed the peak granulite-facies metamorphism. The peak metamorphic assemblage is interpreted to be garnet + biotite + plagioclase + quartz + ilmenite + magnetite with P–T conditions of 860–870 °C and ∼10 kbar. Peak metamorphism was followed by a post-peak near-isothermal decompression with the development of biotite + cordierite + garnet + orthopyroxene + plagioclase + quartz + magnetite at 850–890 °C and ∼7.5 kbar, resulting in the formation of matrix orthopyroxene and cordierite associated with biotite, due to decompressional dehydration melting reactions involving biotite. Thermobarometric data for the mafic granulites show high temperatures of 821–872 °C that are similar to the peak temperatures of the orthopyroxene–cordierite–garnet pelitic granulites. The results indicate that the granulite facies metamorphism of the rocks in the Ji’an area of the Jiao–Liao–Ji Belt was a response to continent–continent subduction and collision of the Longgang and Nangrim blocks of the North China Craton, followed by exhumation.

A great quantity of metamorphic rocks (Haiyangsuo Complex), including high-pressure (HP) mafic granulites with ‘red-eye-circle’ textures, retrogressive products of Grt-, Qtz-, Ep-, and Cpx-bearing amphibolites, TTG–granitic gneisses, and metasedimentary rocks, is distributed extensively within the Haiyangsuo region, northeastern Sulu ultrahigh-pressure (UHP) belt. The Haiyangsuo Complex crops out over an area of at least 70 km2, rather than the 15-km2 area mentioned in previous studies. Based on integrated studies of petrography, mineral phase transformations, mineral inclusions, cathodoluminescence (CL) images of zircons, and zircon U–Pb LA–ICP–MS and amphibole Ar–Ar age dates, together with previous P–T condition estimates, abundant Neoarchean to Early Paleoproterozoic igneous protoliths, including ca. 2.6–2.5 Ga meta-mafic rocks and ca. 2.7 Ga, ca. 2.55–2.5 Ga, and ca. 2.4 Ga TTG–granitic gneisses, were identified in the Haiyangsuo region, whereas the Late Paleoproterozoic (∼1.7 Ga) and Neoproterozoic (ca. 800–650 Ma) protolith ages common in the Sulu HP–UHP rocks have not been observed. The metasedimentary rocks in the region studied have a deposition age of ca. 2.1–1.9 Ga, showing protolith ages similar to those of the voluminous Khondalite series of the Jingshan and Fenzishan groups from the Jiaobei Terrane, southwestern Paleoproterozoic Jiao–Liao–Ji orogenic belt. Two discrete episodic HP granulite–facies metamorphic events were identified for the first time in the meta-mafic rocks of the region and their country rocks. The first episodic HP granulite-facies metamorphism (M1) is characterized by the relict coarse-grained mineral assemblage of garnet (Grt) + clinopyroxene (Cpx) + plagioclase (Pl) ± quartz (Qtz), which formed under P–T conditions of 740–850 °C and 1.0–1.26 GPa. In contrast, the second HP granulite-facies metamorphism (M21) is characterized by ‘red-eye-circle’ textures, with a typical fine-grained mineral assemblage of Grt + Cpx + Pl ± Qtz surrounding the relict coarse-grained HP granulite-facies minerals of M1. It formed under P–T conditions of 765–845 °C and 1.14–1.75 GPa. Both of the HP granulite-facies metamorphic events were overprinted and replaced by a late amphibolite-facies retrogression (M22), which is typified by a fine-grained mineral assemblage of Amp + Pl + Grt and formed under P–T conditions of 580–660 °C and 0.6–0.8 GPa. Abundant metamorphic zircon U–Pb dating revealed that the two discrete episodic HP granulite-facies metamorphic events in the Haiyangsuo Complex occurred and recorded in metamorphic zircon domains with HP granulite-facies mineral inclusions at Late Paleoproterozoic (ca. 1.87–1.86 Ga) and Middle Triassic (ca. 245–225 Ma), respectively, and that each was overprinted by a subsequent amphibolite-facies retrogression at ∼ 1.84 Ga and 220–214 Ma, respectively. Various metamorphic rocks (Haiyangsuo Complex) in the Haiyangsuo region have rock association, petrographical, geochronological, and P–T evolution affinities to the Paleoproterozoic Jiaobei Terrane, SW Jiao–Liao–Ji Belt, but are distinguished from the Sulu UHP rocks. Hence, the Haiyangsuo Complex is exotic to the Sulu UHP belt and can be regarded as an inseparable part of the Jiaobei Terrane during the Paleoproterozoic. The unique Middle Triassic HP granulite-facies metamorphic event first identified within the Haiyangsuo Complex coincides with that (245–225 Ma) of the adjacent Jiaodong Terrane, NE Sulu UHP belt, indicating that the Haiyangsuo Complex was also involved in Triassic collision–subduction and experienced HP granulite-facies metamorphism at a lower crustal level. The ultimate formation of the Haiyangsuo Complex along the southeastern margin of the Jiaobei Terrane, SW Jiao−Liao−Ji orogenic belt, was genetically related to the collision between the North China and South China cratons. Thus, the juxtaposition of the Haiyangsuo Complex to the Sulu UHP metamorphic belt took place in the Middle–Late Triassic rather than in the Jurassic.