Southern Liaoning Research Articles

Evaluating the impact of ecological factors on the quality and habitat distribution of Lonicera japonica Flos using HPLC and the MaxEnt model.

The quality of traditional Chinese medicine is based on the content of their secondary metabolites, which vary with habitat adaptation and ecological factors. This study focuses on Lonicera japonica Flos (LJF), a key traditional herbal medicine, and aims to evaluate how ecological factors impact its quality. We developed a new evaluation method combining high-performance liquid chromatography (HPLC) fingerprinting technology and MaxEnt models to assess the effects of ecological factors on LJF quality. The MaxEnt model was used to predict suitable habitats for current and future scenarios, while HPLC was employed to analyze the contents of key compounds. We also used ArcGIS for spatial analysis to create a quality zoning map. The analysis identified 21 common chromatographic peaks, with significant variations in the contents of Hyperoside, Rutin, Chlorogenic acid, Cynaroside, and Isochlorogenic acid A across different habitats. Key environmental variables influencing LJF distribution were identified, including temperature, precipitation, and elevation. The current suitable habitats primarily include regions south of the Yangtze River. Under future climate scenarios, suitable areas are expected to shift, with notable expansions in southern Gansu, southeastern Tibet, and southern Liaoning. The spatial distribution maps revealed that high-quality LJF is predominantly found in central and southern Hebei, northern Henan, central Shandong, central Sichuan, southern Guangdong, and Taiwan. The study indicates that suitable growth areas can promote the accumulation of certain secondary metabolites in plants, as the accumulation of these metabolites varies. The results underscore the necessity of optimizing quality based on cultivation practices. The integration of HPLC fingerprinting technology and the MaxEnt model provides valuable insights for the conservation and cultivation of herbal resources, offering a new perspective on evaluating the impact of ecological factors on the quality of traditional Chinese medicines.

Prediction of potential suitable habitats in the 21st century and GAP analysis of priority conservation areas of Chionanthus retusus based on the MaxEnt and Marxan models.

Chionanthus retusus (C. retusus) has a high economic and medicinal value, but in recent years it has been included in the list of China's major protected plants and China's Red List of Biodiversity due to the serious destruction of its wild germplasm resources. Based on 131 sample points of C. retusus, this study simulated potential habitats and spatial changes of C. retusus in the 21st century using the Maxent model combined with the geographic information system ArcGIS, predicted prioritized protected areas by the Marxan model, and assessed current conservation status through GAP analysis. The results showed that (1) when the regularization multiplier was 1.5 and the feature combinations were linear, quadratic, and fragmented, the area under the curve of the subjects in the training and test sets were both above 0.9, the true skill statistic value was 0.80, and the maximum Kappa value was 0.62, meaning that the model had high accuracy; (2) Temperature seasonality, annual precipitation, min temperature for coldest month, and precipitation of wettest month had relatively strong influences on species' ranges. (3) The moderately and optimally suitable habitats of C. retusus were primly located in the areas of southwestern Shanxi, central Hebei, western Henan, Shandong, Shaanxi, Anhui and Hubei; (4) Under different future climate scenarios, the area of each class of suitable habitat will increase for varied amounts compared to the current period, with a general trend of expansion to the south; (5) The C. retusus priority protected areas were mainly located in most of Shandong, southern Liaoning, southwestern Shanxi, western Henan, and central Hebei, and its conservation vacancy area was relatively large compared to its protected area. These results will provide scientific strategies for implementing long-term conservation of C. retusus in China and similar regions under warming conditions in the 21st century.

Spatiotemporal evolution and influencing factors of urban growth and shrinkage in Central and Southern Liaoning: Based on the perspective of physical urban area

Spatiotemporal evolution and influencing factors of urban growth and shrinkage in Central and Southern Liaoning: Based on the perspective of physical urban area

Characteristics of Early Neoproterozoic Stromatolites from Southern Liaoning, North China: Insights into the Formation of Stromatolites

Stromatolites, among the earliest fossils in Earth’s history, are widely distributed on the margins of the North China Precambrian carbonate platform. The formation processes of stromatolites reveal the biomineralization and evolution of early life in the Precambrian. The well-preserved stromatolitic dolostones recorded in the Ganjingzi Formation are developed around Yuanjiagou village, in southern Liaoning Province. The morphology of the Ganjingzi stromatolites manifests in stratiform, columnar, and domal forms. A tripartite lamina structure including light laminae and two types of dark laminae is observed in thin sections. The origins of dark laminae were related to microbial metabolism, while the light laminae were the result of the recrystallization of synsedimentary marine cement. Hardground substrate and carbonate fragments were suitable for microbes to colonize, suggesting that microbes can adapt to various current energy settings. A comparison of the growth environment, morphology, and laminae features between the Ganjingzi stromatolites and modern carbonate stromatolites from Hamelin Pool and Lagoa Vermelha suggest that the Ganjingzi stromatolites may have been formed in a restricted tidal-flat setting with high salinity and evaporation. The role of microbes that form modern stromatolites in inducing precipitation of carbonate or binding sediments, might contribute to the formation of the Ganjingzi stromatolites. The formation process of the Ganjingzi stromatolites indicates that the microbial communities, favorable substrate, and synsedimentary marine cement were the key factors in promoting the development of the Neoproterozoic stromatolites on the northeastern margin of the North China Craton.

Evaluation of urban flooding and potential exposure risk in central and southern Liaoning urban agglomeration, China

Urban flooding is an important natural hazard that affects urban security in the context of global climate change and urbanization. The simulation of stormwater inundation and risk assessment in urban environments is critical for the sustainable development of urban agglomerations. However, few studies have focused on rainstorm flooding at the urban agglomeration scale. In this study, the Central and Southern Liaoning Urban Agglomeration (CSLN) was selected a case study. A method was proposed to assess the urban flooding and potential exposure risk. The urban flooding of CSLN was characterized by the average flooding depth (AFD) of each sub-catchment, and exposure risk was indicated by potential regional and population exposure risk. The results illustrate that the AFD increased with an increase in the rainfall return period, especially in the urban core. The AFD of each city in the CSLN ranged from 10 to 80 mm, and there were strong differences among cities. The spatial distribution of urban flooding in the nine cities presented aggregation characteristics, and hotspots were mainly concentrated in the old urban districts. The potential regional exposure risk tended to increase as the rainfall return period increased from 10 to 100 years; however, there were significant differences among cities. Among them, the area of potential regional exposure risk in Shenyang was the largest, increasing from 365 km2 under a 10-year rainfall return period to 463 km2 under a 100-year rainfall return period. The largest proportion of potential regional exposure risk was in Anshan, which increased from 3% under 10-year to 13.8% under 100-year rainfall return periods. Most cities had some potential population exposure risk. More residents in populous cities, such as Shenyang and Dalian, were subject to higher exposure risks. However, Benxi, Anshan, and Tieling had a high proportion of severely affected areas, although the size of their cities is much smaller than that of Shenyang and Dalian. Urban flooding and potential exposure risk were apparently higher in the business and government zones than in the industrial and greenspace zones. These methods and results may provide references for rainstorm flooding mitigation through urban planning in urban agglomeration areas.

New record of the green algal fossil Proterocladus and coexisting microfossils from the Meso-Neoproterozoic Diaoyutai Formation in southern Liaoning, North China

The Mesoproterozoic-Neoproterozoic transition represents a crucial interval of evolutionary innovation and phylogenetic diversification. A spotty fossil record indicates that several clades of multicellular eukaryotes, including red and green algae, as well as fungi, may have diverged and diversified at this transition. However, the Meso-Neoproterozoic fossil record remains poorly documented, particularly at the assemblage level, greatly limiting our understanding of the marine ecosystem in this critical time interval. Here we report a well-preserved assemblage of organic-walled microfossils from the Meso-Neoproterozoic Diaoyutai Formation (ca. 1050–950 Ma) in Southern Liaoning Province of the North China Block. Raman geothermometric analysis of these organic-walled microfossils suggests that the Diaoyutai Formation experienced relatively low-grade metamorphism, with apparent peak metamorphic temperatures of ∼ 215 ℃. The Diaoyutai assemblage consists of 14 species belonging to 9 genera, as well as several unnamed or unidentified forms. In addition to simple forms such as aggregated coccoidal and unbranched filamentous fossils that are often interpreted as cyanobacteria, a moderate diversity of eukaryotes is also observed. Probable eukaryotic fossils in this assemblage include the branched multicellular alga Proterocladus antiquus that has been previously interpreted as a green alga, several morphologically complex spheroidal taxa (e.g., Germinosphaera bispinosa, Pterospermopsimorpha insolita, P. pileiformis and Squamosphaera colonialica), and relatively large leiospheres (50–700 μm in diameter). We note that the occurrence of Proterocladus antiquus in the Diaoyutai assemblage predates its previously reported occurrence from the overlying Nanfen Formation. Overall, the Diaoyutai assemblage presents a glimpse of the coastal marine ecosystem at the Meso-Neoproterozoic transition, which consisted of benthic microbial mats dominated by filamentous cyanobacteria, millimeter-sized benthic green algae with thallus elevating above the sediment–water interface, and micrometer-sized planktonic prokaryotic and eukaryotic organisms. From the perspective of primary producers, the rise of photosynthetic eukaryotes in the Meso-Neoproterozoic represents a transformative innovation to modernize the coastal marine ecosystem in terms of ecological functions.

Assessing progress towards sustainable development goals for Chinese urban land use: A new cloud model approach

Rapid urbanization poses great challenges to China's urban land use sustainability (ULUS). Land is the essential space to achieve the Sustainable Development Goals (SDGs) of the United Nations, so SDGs provide a new guide to evaluate land use sustainability. However, there is still a lack of SDGs-oriented assessment of urban land use at national level. Moreover, there is still a need to address the problems about the randomness and fuzziness within evaluation, which tends to cause more uncertainties. Here we developed a SDGs-oriented evaluation framework based on the cloud model and derived the spatial and temporal patterns of urban land use sustainability for China at the prefecture-level from 2004 to 2019. Then, we used the McKinsey matrix to classify the types of urban land use sustainability, and examined their main drivers using the Geodetector method. The results showed that the development level of ULUS in China was high in the east and low in the west. High-value hotspots were mainly distributed in primary and secondary urban agglomerations in China. From 2004 to 2019, the development level of ULUS in China gradually increased, but the growth rate slowed down. In 2009 the value of central China exceeded that of the northeast. In contrast, the coordination level of ULUS had declined in more than 50% of Chinese cities during the study period. The high values were in southern China, northeast China, and Chengdu-Chongqing urban agglomeration, while the low values were in central and southern Liaoning and the urban agglomeration in the Central Plains. The development level was mainly controlled by anthropogenic activities and urban development, while natural conditions constrained the improvement of the coordination level. Combining the development and coordination, we found that cities with higher development level often had a wide range of coordination level, and suggestions were put forward for different regions to achieve sustainable land use. Our research provides scientific guidance for China's territory planning and sustainable urban development.

Early Neoproterozoic well-preserved stromatolites from southern Liaoning, North China: characteristics and paleogeographic implications

We report morphology and microstructure of the stromatolites of the Ganjingzi Formation in southern Liaoning. Sedimentologic and morphologic analyses indicate that the lower stromatolite mounds formed in a transgressive succession, while the stromatolite columns in the more complex upper biostrome changed vertically from dispersed growth to dense clumping. Biostratigraphic analysis shows that the stromatolites in the Ganjingzi Formation are similar to those from coeval strata in the Xuzhou-Huainan Region and in southern Jilin. Comparisons of the morphotype genera of stromatolites and the sedimentary setting between different areas, imply that sea-level was fluctuating in the east of the North China Craton (NCC) during the Ganjingzi interval and that the transgressions were beneficial to stromatolite growth, as indicated by the increased number of stromatolites in the study area.

Study on Eco-Environmental Effects of Land-Use Transitions and Their Influencing Factors in the Central and Southern Liaoning Urban Agglomeration: A Production–Living–Ecological Perspective

From the perspective of the production–living–ecological space, this paper reclassifies the land-use categories in the central and southern Liaoning urban agglomeration in the years 1990, 2000, 2010 and 2018. It then quantitatively analyzes the spatiotemporal evolution characteristics of land-use transitions by adopting the land-use transfer matrix and other methods. This paper further uses the eco-environmental quality index and ecological contribution rate to explore the eco-environmental effects of the land-use transition. Finally, it identifies the influencing factors of the eco-environmental effect and the spatial differentiation law of the effect in the study area through the multi-scale geographically weighted regression (MGWR) model. The main conclusions reached are as follows: (1) During the study period, a slow increase was seen in the ecological land of the central and southern Liaoning urban agglomeration. A sharp decline occurred in the production land, and a rapid rise was found in the living land. (2) From 1990 to 2018, the eco-environmental quality index in the study region showed significant spatial differentiation, with the distribution characteristics being high in the east and low in the west. The areas have expanded and spread along the Shenyang-Dalian axis to form medium-low quality agglomerations. The encroachment of agricultural production land and urban and rural living land on forest ecological land is the main contributor to the deterioration of the eco-environmental quality during the study period. (3) Compared with the geographically weighted regression model and the ordinary least squares model, a remarkable advancement can be seen in the MGWR model, which is more suitable for research on the influencing factors of eco-environmental quality. In addition, different influencing factors have significant spatial differences in the degree and scale of impact.

Multi-Year Variation of Ozone and Particulate Matter in Northeast China Based on the Tracking Air Pollution in China (TAP) Data.

With the rapid development of economy and urbanization acceleration, ozone (O3) pollution has become the main factor of urban air pollution in China after particulate matter. In this study, 90th percentile of maximum daily average (MDA) 8 h O3 (O3-8h-90per) and PM2.5 data from the Tracking Air Pollution in China (TAP) dataset were used to determine the mean annual, seasonal, monthly, and interannual distribution of O3-8h-90per and PM2.5 concentrations in Northeast China (NEC). The O3-8h-90per concentration was highest in Liaoning (>100 μg/m3), whereas the highest PM2.5 concentration was observed mainly in urban areas of central Liaoning and the Harbin–Changchun urban agglomeration (approximately 60 μg/m3). The O3-8h-90per concentrations were highest in spring and summer due to more intense solar radiation. On the contrary, the PM2.5 concentration increased considerably in winter influenced by anthropogenic activities. In May and June, the highest monthly mean O3-8h-90per concentrations were observed in central and western Liaoning, about 170–180 μg/m3, while the PM2.5 concentrations were the highest in January, February, and December, approximately 100 μg/m3. The annual mean O3-8h-90per concentration in NEC showed an increasing trend, while the PM2.5 concentration exhibited an annual decline. By 2020, the annual mean O3-8h-90per concentration in southern Liaoning had increased considerably, reaching 120–130 μg/m3. From the perspective of city levels, PM2.5 and O3-8h-90per also showed an opposite variation trend in the 35 cities of NEC. The reduced tropospheric NO2 column is consistent with the decreasing trend of the interannual PM2.5, while the increased surface temperature could be the main meteorological factor affecting the O3-8h-90per concentration in NEC. The results of this study enable a comprehensive understanding of the regional and climatological O3-8h-90per and PM2.5 distribution at distinct spatial and temporal scales in NEC.

Effects of different returning method combined with decomposer on decomposition of organic components of straw and soil fertility

In view of the problems of low straw decomposition rates and reduced soil fertility in southern Liaoning, China, we investigated the effects of no-tillage mode (NT), deep loosening + deep rotary tillage mode (PT), rotary tillage mode (RT) and the addition of decomposing agent (the next is called a decomposer) (NT + S, PT + S, RT + S) on the decomposition proportion of straw, respectively, by using the nylon net bag method in combination with 365-day field plot experiments. The decomposition rules of cellulose, hemicellulose and lignin as well as the dynamics of soil organic carbon (SOC), soil microbial biomass carbon (MBC) and soil dissolved organic carbon (DOC) in straw returned to the field for 15, 35, 55, 75, 95, 145 and 365 days were analyzed. The results showed that in the short term, the decomposition of straw was better in both the rotray tillage and deep loosening + deep rotary modes than in the no-tillage mode, and the addition of decomposer significantly promoted the decomposition of straw and the release of carbon from straw, among them, the RT + S treatment had the highest straw decomposition proportion and carbon release proportion in all sampling periods. After a one year experimental cycle, the RT + S treatment showed the highest proportion of cellulose, hemicellulose and lignin decomposition with 35.49%, 84.23% and 85.50%, respectively, and soil SOC, MBC and DOC contents were also higher than the other treatments with an increase of 2.30 g kg−1, 14.22 mg kg−1 and 25.10 mg kg−1, respectively, compared to the pre-experimental soil. Our results show that in the short term, to accelerate the decomposition rate of returned straw and increase the content of various forms of carbon in soil, rotary tillage can be used to return the straw to the field, while also spraying straw decomposer on its surface. This experiment used a new straw decomposer rich in a variety of microorganisms, combined with the comparison of a variety of straw return modes, and in-depth study of straw decomposition effects of cellulose, hemicellulose and lignin. Thus, a scheme that can effectively improve the decomposition rate of straw and the content of various forms of organic carbon in soil within a short period of time was explored to provide theoretical support for the southern Liaoning.

The role of titanite in shaping the geochemistry of amphibolite-derived melts

Titanite, one of the major accessory phases in middle to lower crustal rocks, could play an important role in shaping trace element as well as radiogenic isotope compositions in amphibolite-derived melts. Petrographic, zircon U/Pb, whole-rock element and isotope (Sr and Nd) data on a suite of leucosomes, and titanite Nd isotope compositions from the migmatitic amphibolite complex, southern Liaoning, indicate that (1) the amphibolite with a protolith age of ~2450 Ma underwent low-degree partial melting at ~160 Ma and produced two groups of leucosome; (2) these leucosomes preserved a large magnitude of Nd isotope disequilibrium with up to ~10 epsilon units of difference with respect to their sources; (3) differential dissolution of titanite during partial melting might lead to negative correlations between Nd isotope compositions and respective Ti or V contents (proxy of the amount of titanite presented). These data indicates that during low-degree partial melting of mafic rocks, titanite stays as a residue phase due to either unfavorable texture or melting (temperature or fluid) conditions and leads to the development of melts with depletion in Ti-affinity elements, REE, and a large positive shift in Nd isotope compositions. Similar to other accessory phases (e.g., zircon, apatite, and monazite) in metasedimentary sources, this contribution presents another case that could be common in high-grade metamorphic terranes in which titanite could be a key phase that controls key trace element (e.g. NbTa, V, and REE) budget and Nd isotope compositions in melts derived from low-pressure melting of amphibolite or mafic rocks in various tectonic environments.

Land use efficiency and technology gaps of urban agglomerations in China: An extended non-radial meta-frontier approach

With the rapid development of urban agglomerations (UAs), the contradiction between the shortage of land resources and the sustainable development has become increasingly apparent. Considering regional heterogeneity, this paper proposes a generalized non-radial meta-frontier DEA framework to measure the land use performance of 12 typical UAs covering 184 cities in China during 2006–2015. To be specific, this approach effectively avoids unreasonable technology gap ratio values in non-radial DEA models, and decomposes the land use performance loss into technology gaps and management inefficiency. The results show that 1) In terms of the efficiency values under meta-frontier, the land use performance of most UAs is relatively low, whereas the development of cities within each UA are balanced with high group efficiencies. 2) The technology levels of the 12 UAs are inconsistent, in which Yangtze River Delta UA equips with the most advanced technology while Southern Liaoning UA has the lowest technology level. 3) The improvement direction and potential efficiencies of cities also differ. Based on technical potential and management potential, the cities and UAs are divided into three categories. Finally, based on the assessment results, related policy implications to promote the land use performance of China's UAs are proposed.

Combined Magnetic, Transient Electromagnetic, and Magnetotelluric Methods to Detect a BIF-Type Concealed Iron Ore Body: A Case Study in Gongchangling Iron Ore Concentration Area, Southern Liaoning Province, China

The detection and evaluation of concealed mineral resources deep in metallic mines and in the surrounding areas remain technically difficult. In particular, due to the complex topographic and geomorphic conditions on the surface, the detection environments in these areas limit the choices of detection equipment and data collection devices. In this study, based on metallogenic theory and the metallogenic geological characteristics of banded iron formation (BIF)-type iron ores, equipment for surface geophysical surveys (i.e., the high-precision ground magnetic survey method, the transient electromagnetic method, and the magnetotelluric method) and data collection devices capable of taking single-point continuous measurements were employed to detect the concealed iron ore bodies in the transition zone CID-1 between the Hejia and Dumu iron deposits in the Gongchangling iron ore concentration area in the Anshan-Benxi area (Liaoyang, China), a representative area of BIF-type iron ores. The results showed that an optimal combination of these geophysical survey methods accurately determined the anomalous planar spatial locations and anomalous profile morphologies of the concealed iron ore bodies. On this basis, we determined their locations, burial depths, and scales. Two anomalous zones induced by concealed iron ore bodies, YC-1 and YC-2, were discovered in zone CID-1. Two concealed iron-bearing zones, one shallow (0–150 m) and one deep (300–450 m), were found in YC-1. A 100 m scale drilling test showed that the cumulative thickness of the shallow iron-bearing zone was over 23.6 m.

Sequence stratigraphic division of the Shisanlitai Formation of Neoproterozoic in Southern Liaoning, China

Sequence stratigraphy is the most important prediction theory in the field of petroleum exploration, and is hailed as a theoretical revolution in geology. At present, countries around the world have begun to pay attention to the study of marine carbonate rocks. The Shisanlitai Formation in Dalian, Liaoning is an important Neoproterozoic stratum in China, with a large number of carbonate rocks. Through comprehensive analysis of the field measured profiles, the sequence stratigraphy of the Shisanlitai Formation was studied. A total of 4 sequence boundary were identified, and 3 sequence, 7 para-sequence sets and 20 para-sequences were divided. It is considered that the Shisanlitai Formation is a platform marginal sedimentary facies. The regional geotectonic and astronomical cyclic methods are used to discuss the environmental evolution of the Ganjingzi Formation. Platform marginal beach → platform marginal slope → platform marginal reef evolution process, and summarized that there were 4 short exposures from the end of the Majiatun period to the Shisanlitai Formation period in the Dalian area affected by the low-amplitude tectonic ups and downs in the late Yangtze cycle 4 sequence boundary and 3 sequences are formed. Through comprehensive and systematic analysis of the sequence stratigraphy and sedimentary evolution of the Shisanlitai Formation, it provides a basis for exploring the oil and gas resources in southeastern Liaoning.

Spatially Explicit Assessment of Social Vulnerability in Coastal China

Social vulnerability assessment has been recognized as a reliable and effective measure for informing coastal hazard management. Although significant advances have been made in the study of social vulnerability for over two decades, China’s social vulnerability profiles are mainly based on administrative unit. Consequently, no detailed distribution is provided, and the capability to diagnose human risks is hindered. In this study, we established a social vulnerability index (SoVI) in 2000 and 2010 at a spatial resolution of 250 m for China’s coastal zone by combining the potential exposure index (PEI) and social resilience index (SRI). The PEI with a 250 m resolution was obtained by fitting the census data and multisource remote sensing data in random forest model. The county-level SRI was evaluated through principal component analysis based on 33 socioeconomic variables. For identifying the spatiotemporal change, we used global and local Moran’s I to map clusters of SoVI and its percent change in the decade. The results suggest the following: (1) Counties in the Yangtze River Delta, Pearl River Delta, and eastern Guangzhou, except several small hot spots, exhibited the most vulnerability, especially in urban areas, whereas those in Hainan and southern Liaoning presented the least vulnerability. (2) Notable increases were emphasized in Tianjin, Yangtze River Delta, and Pearl River Delta. The spatiotemporal variation and heterogeneity in social vulnerability obtained through this analysis will provide a scientific basis to decision-makers to focus risk mitigation effort.

Sequence stratigraphy of the Cambrian Terreneuvian Dalinzi Formation in southern Liaoning

As one of the only Cambrian Terreneuvian rock stratas in southern Liaoning, the Dalinzi Formation is of great significance for studying the evolution of the Early Cambrian sedimentary basin and the global sea level change in North China. Taking the Zhaokanzi section as an example, the sedimentary facies of the Dalinzi Formation in southern Liaoning were identified, and then the sequence stratigraphy was studied. The study suggests that the Dalinzi Formation is formed in the lagoon and tidal flat sedimentary environment, and a three-level sequence and several parasequences and parasequence sets can be divided. The relative sea level changes and sedimentary basin evolution are discussed.

“三生”融合下的辽南滨河地区田园综合体规划探究——以浮渡河田园综合体为例

“三生”融合下的辽南滨河地区田园综合体规划探究——以浮渡河田园综合体为例

Early Mesozoic intracontinental deformation in the eastern North China Block: Implication for an indentation model of North China to South China blocks

The Qinling‐Dabie‐Sulu Orogen was formed by the collision of the North and South China blocks during the Indosinian Period. The intracontinental deformation was subsequently developed during the Late Triassic to Early Jurassic in the northeastern, eastern, and southeastern parts of eastern North China Block with different structural patterns. In this paper, we present structural analysis of the Indosinian deformation in the western Shandong and southern Liaoning provinces and synthesized the previous studies of the Triassic‐Early Jurassic deformation in different areas of the eastern North China Block, from the northeastern, central to southeastern parts. Integrating the previous studies of petrology, geochronology, and geophysics, we suggested that (1) a series of top‐to‐the‐northwest thrust‐nappes were formed in the Sulu Orogen, and the southeastward antithetic faults developed in the South China Block. In the eastern North China Block, the Indosinian intracontinental deformation is intensely developed near the orogenic belt as thrust‐nappes and away from the belt developed open folds. (2) The present‐day structural lines in the northeastern, central, and southeastern parts of eastern North China Block show the S‐N‐, E‐W‐, and NE‐trending lines, respectively. It could be the structural response to the dynamics of an orocline or indentation induced by Triassic collision of the North and South China blocks; (3) the eastern margin of the North China Block subducted southeastward beneath the South China Block along the Wulian‐Qingdao‐Yantai Fault during the Indosinian Period.

Geochemistry, U-Pb dating, and Lu-Hf isotopes of zircon and monazite of porphyritic granites within the Jiao-Liao-Ji orogenic belt: Implications for petrogenesis and tectonic setting

Abundant porphyritic granites, including Grt-bearing and Bt-bearing porphyritic granites, and flesh-red porphyritic granites, as various scale batholiths are widely distributed within the Jiao-Liao-Ji belt (JLJB), which extends for a distance of at least 1000km, rather than being limited to sporadic outcrops in southern Liaoning and Jilin as stated in previous studies. On the basis of morphology, CL and BSE zoning patterns, and mineral inclusions of dated zircon and monazite grains from samples of various porphyritic granites, the grains exhibit evident magmatic zones with distinct cores and rims and preserve felsic mineral inclusions of Qtz+Kfs+Pl+Qtz±Ap in both domains. The magmatic zircon cores and rims from 18 dated samples yielded two distinct weighted mean age groups, from 1872±9 to 1866±7Ma and 1851±14 to 1842±10Ma, with age peaks at 1869±1.7 and 1848±2.4Ma, respectively. Similarly, the magmatic cores and rims of monazites from 10 dated samples also showed two distinct weighted mean age groups, from 1870±3 to 1864±2Ma and 1851±6 to 1842±12Ma, with age peaks at 1868±0.8 and 1847±1.2Ma, respectively. The numerous U-Pb age data of both zircons and monazites revealed that the JLJB experienced a major episode of granitic magmatism in the Paleoproterozoic with initial emplacement timing of melts at ∼1.87Ga and crystallisation end timing of melts at ∼1.84Ga as represented by the magmatic cores and rims of the zircons and monazites, respectively. A combined study of whole-rock geochemistry and zircon Lu-Hf isotopic analyses revealed that the three types of porphyritic rocks are enriched in HREE, Zr, Nb, Ga, and Y and are depleted in V, Cr, and Ni, and that most have high TFeO/MgO ratios and Zr-saturation temperatures of ∼850°C, which is suggestive of an affinity with A-type granite. Moreover, the dominant εHf(t) values of the magmatic zircons range from −4.8 to +3.3, which is consistent with those of the 2.2–2.1Ga calc-alkaline meta-granites in the JLJB. Considering the high contents of garnet, Al-rich paragneiss enclaves, and ∼1.92Ga inherited metamorphic zircons in the granites, these porphyritic rocks were most likely derived from the partial melting of the 2.2–2.1Ga calc-alkaline meta-granites with abundant involvement of Al-rich pelitic granulites from the basement of the JLJB. As the result of a newly combined study of traditional geothermobarometers and phase equilibria modelling together with geochronological U-Pb dating, a precise clockwise P-T-t path with a subsequent near isothermal decompression process has been well determined in the HP-MP granulite facies metamorphic rocks in the JLJB. Thus, the following sequence of events can be inferred. Abundant ∼2.2–2.1Ga granitic rocks and voluminous Paleoproterozoic sedimentary rocks were subducted to lower crustal depths and underwent a peak HP-MP granulite facies metamorphism at 1950–1900Ma. These granulite facies rocks were exhumed to middle crustal levels and experienced a post-peak MP-LP granulite facies metamorphism at 1875–1840Ma. The retrograde rocks continued to be exhumed to shallow crustal levels at 1830–1800Ma and were finally overprinted by late amphibolite facies retrogression. The numerous magmatic zircons and monazites from the various porphyritic granites record a distinct Paleoproterozoic granitic magmatic event with two evident age peaks of ∼1.87Ga and ∼1.84Ga, which are completely consistent with the post-peak MP-LP granulite facies metamorphism (1875–1840Ma), representing an anorogenic magmatic association formed in an extensional setting possibly resulting from mantle upwelling and lithospheric thinning and resulting in the violent partial melting of ∼2.2–2.1Ga meta-granites along with abundant Al-rich pelitic granulites. Considering these data in combination with previous whole-rock geochemistry and age data, it can be stated that similar porphyritic granites are not only limited to the entire JLJB but are also widely distributed in North and South Korea. Thus, it can be concluded that the ∼1.87–1.84Ga porphyritic granites, together with massive rapakivi granites, Kfs-megacrysts, and porphyritic monzogranites, as products of an anorogenic granitic magmatic event, may have widely formed in both the JLJB and Korean Peninsula in an extensional and thinning tectonic setting.