The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed ＂dual-track＂ structure...The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed ＂dual-track＂ structure of rural-urban development in China as well as un- stable rural development institution and mechanism. It is necessary to restructure rural pro- duction, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realizing urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring. Basing on the effects analysis of industrialization and urbanization on rural production, living and ecological space, the mechanism of pushing forward rural spatial restructuring by carry- ing out land consolidation is probed. A conceptualization of the models of rural production, living and ecological spatial restructuring is analyzed combining with agricultural land con- solidation, hollowed villages consolidation and industrial and mining land consolidation. Fi- nally, the author argues that a ＂bottom-up＂ restructuring strategy accompanied by a few ＂top-down＂ elements is helpful for smoothly pushing forward rural spatial restructuring in China. In addition, the optimization and restructuring of rural production, living and ecological space will rely on the innovations of regional engineering technology, policy and mechanism, and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development.展开更多
Rural hollowing is a recent geographic phenomenon that has received significant attention in China, which is experiencing rapid urbanization. It has led to the wasteful use of rural land resources, and imposed obstacl...Rural hollowing is a recent geographic phenomenon that has received significant attention in China, which is experiencing rapid urbanization. It has led to the wasteful use of rural land resources, and imposed obstacles on the optimization of land use and coordinated urban-rural development. Rural hollowing has various forms of manifestation, which refers to the neglect and vacancy of rural dwellings, both of which can lead to damage and ultimate abandonment of rural dwellings. Damaged dwellings have different degrees of destruction, ranging from slight, moderate to severe. The evolutive process of rural hollowing in general has five stages, i.e., emergence, growth, flourishing, stability, and decline. Based on the combination of both regional economic development level and its physiographic features, the types of rural hollowing can be categorised as urban fringe, plain agricultural region, hilly agricultural region, and agro-pastoral region. Especially, the plain agricultural region is the most typical one in rural hollowing, which shows the spatial evolution of rural hollowing as a ＂poached egg＂ pattern with a layered hollow core and solid shape. Furthermore, the driving forces behind rural hollowing are identified as the pull of cities and push of rural areas. In particular, this paper identifies contributors to rural hollowing that include rural depopulation in relation to rapid urbanisation and economic change, land ownership and land use policy, and institutional barriers.展开更多
Based on the acquaintance of the regional background of urban-rural transformational development and investigations on the spot,this paper discusses the holistic situation, dominant factors and mechanism of arable lan...Based on the acquaintance of the regional background of urban-rural transformational development and investigations on the spot,this paper discusses the holistic situation, dominant factors and mechanism of arable land loss and land for construction occupation in the coastal area of China over the last decade,with the aid of GIS technology.Conclusions of the research are summarized as follows：（1）the arable land had been continuously decreasing from 1996 to 2005,with a loss of 1,708,700 hm^2 and an average decrement of 170,900 hm^2 per year;（2）land for construction increased 1,373,700 hm^2 ,with an average increment of 153,200 hm^2 per year;（3）total area of encroachment on arable land for construction between 1996 and 2005 was 1,053,100 hm^2 ,accounting for 34.03%of the arable land loss in the same period,the percentages of which used for industrial land（INL）,transportation land（TRL）,rural construction land（RUL）and town construction land（TOL）are 45.03%,15.8%,15.47%and 11.5%,respectively;and（4）the fluctuation of the increase of construction land and encroachment on arable land in the area were deeply influenced by the nation＇s macroscopic land-use policies and development level of regional economy.The growth of population and advancement of technology promoted the rapid industrialization, construction of transportation infrastructures,rural urbanization and expansion of rural settlements in the eastern coastal area,and therefore were the primary driving forces of land-use conversion.展开更多
AIM: To compare the therapeutic effect and significances of multimodality treatment for hepatocellular carcinoma (HCC) with tumor thrombi in portal vein (PVTT). METHODS: HCC patients (n=147) with tumor thrombi in the ...AIM: To compare the therapeutic effect and significances of multimodality treatment for hepatocellular carcinoma (HCC) with tumor thrombi in portal vein (PVTT). METHODS: HCC patients (n=147) with tumor thrombi in the main portal vein or the first branch of portal vein were divided into four groups by the several therapeutic methods. There were conservative treatment group in 18 out of patients (group A); and hepatic artery ligation(HAL) and/or hepatic artery infusion (HAI) group in 18 patients (group B), in whom postoperative chemoembolization was done periodically; group of removal of HCC with PVTT in 79 (group C) and group of transcatheter hepatic arterial chemoembolization (TACE) or HAI and/or portal vein infusion (PVI) after operation in 32 (group D). RESULTS: The median survival period was 12 months in our series and the 1-,3-, and 5-year survival rates were 44.3%, 24.5% and 15.2%, respectively. The median survival times were 2, 5, 12 and 16 months in group A, B, C and D, respectively. The 1-, 3- and 5-year survival rates were 5.6%, 0% and 0% in group A; 22.2%, 5.6% and 0% in group B; 53.9%, 26.9% and 16.6% in group C; 79.3%, 38.9% and 26.8% in group D, respectively. Significant difference appeared in the survival rates among the groups (P 【 0.05). CONCLUSION: Hepatic resection with removal of tumor thrombi and HCC should increase the curative effects and be encouraged for the prolongation of life span and quality of life for HCC patients with PVTT, whereas the best therapeutic method for HCC with PVTT is with regional hepatic chemotherapy or chemoembolization after hepatic resection with removal of tumor thrombi.展开更多
An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12^th, 2008 and resulted in long surface ruptures （〉300 km）. The first-hand observations about the surface ruptures produced by the earth...An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12^th, 2008 and resulted in long surface ruptures （〉300 km）. The first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co-seismic vertical displacements along the individual fault of the Yingxiu-Beiehuan rupture zone reach 2.514 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5-6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2-3 m dextral strike-slip component. The Wenchuan thrust-faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.展开更多
Artificial bee colony(ABC) is one of the most popular swarm intelligence optimization algorithms which have been widely used in numerical optimization and engineering applications. However, there are still deficiencie...Artificial bee colony(ABC) is one of the most popular swarm intelligence optimization algorithms which have been widely used in numerical optimization and engineering applications. However, there are still deficiencies in ABC regarding its local search ability and global search efficiency. Aiming at these deficiencies,an ABC variant named hybrid ABC(HABC) algorithm is proposed.Firstly, the variable neighborhood search factor is added to the solution search equation, which can enhance the local search ability and increase the population diversity. Secondly, inspired by the neuroscience investigation of real honeybees, the memory mechanism is put forward, which assumes the artificial bees can remember their past successful experiences and further guide the subsequent foraging behavior. The proposed memory mechanism is used to improve the global search efficiency. Finally, the results of comparison on a set of ten benchmark functions demonstrate the superiority of HABC.展开更多
Field survey and greenhouse experiments were carried out to identify and characterize zinc (Zn) uptake and accumulation by a new Zn hyperaccumulating plant species (Sedum alfredii Hance) native to China. Zinc concentr...Field survey and greenhouse experiments were carried out to identify and characterize zinc (Zn) uptake and accumulation by a new Zn hyperaccumulating plant species (Sedum alfredii Hance) native to China. Zinc concentration in the shoots of Sedum alfredii Hance grown on an ancient mined area ranged from 4134 to 5000 mg/kg, with a mean of 4515 mg/kg. It suggests that Sedum alfredii could not only grow on heavily Pb/Zn contaminated soils, but also could accumulate extraordinarily high concentration of Zn. Under nutrient solution culture conditions, Sedum alfredii Hance grew healthy at Zn supplying levels from 0.006 to 240 mg · L-1. Zinc concentration in the shoots increased with external Zn levels increasing. The Zn concentration and accumulation in the shoots reached the highest at Zn supply level of SO mg/L, with 19.67 g/kg and 19.83 nig/plant, respectively. All the results showed that Sedum alfredii Hance is a new Zn hyperaccumulating plant. This provides a new plant material to explore mechanism of展开更多
Land use transition refers to the changes in land use morphology （both dominant morphology and recessive morphology） of a certain region over a certain period of time driven by socio-economic change and innovation, ...Land use transition refers to the changes in land use morphology （both dominant morphology and recessive morphology） of a certain region over a certain period of time driven by socio-economic change and innovation, and it usually corresponds to the transition of socio-economic development phase. In China, farmland and rural housing land are the two major sources of land use transition. This paper analyzes the spatio-temporal coupling characteristics of farmland and rural housing land transition in China, using high-resolution Landsat TM （Thematic Mapper） data in 2000 and 2008, and the data from the Ministry of Land and Resources of China. The outcomes indicated that： （1） during 2000-2008, the correlation coefficient of farmland vs. rural housing land change is -0.921, and it shows that the change pattern of farmland and rural housing land is uncoordinated; （2） the result of Spearman rank correlation analysis shows that rural housing land change has played a major role in the mutual transformation of farmland and rural housing land; and （3） it shows a high-degree spatial coupling between farmland and rural housing land change in southeast China during 2000-2008. In general, farmland and rural housing land transition in China is driven by socio-economic, bio-physical and managerial three-dimensional driving factors through the interactions among rural population, farmland and rural housing land. However, the spatio-temporal coupling phenomenon and mechanism of farmland and rural housing land transition in China are largely due to the ＂dual-track＂ structure of rural-urban development.展开更多
Based on multiple remote-sensing image interpretation and classification, and economic and social data, this study focused on rural settlement and land use change amidst rapid urbanization. Rural settlements, spatial ...Based on multiple remote-sensing image interpretation and classification, and economic and social data, this study focused on rural settlement and land use change amidst rapid urbanization. Rural settlements, spatial and temporal patterns of land use and influ- encing factors in the Bohai Rim were explored within 5x5 km grid cells, as per GIS spatial analysis and geostatistical analysis. Results show that the spatial distribution of rural settle- ments in the Bohai Rim is remarkably varied. The number of rural settlement sites in a 5x5 km grid cell exceeding 5.0 are distributed in a six-area pattern in the Bohai Rim; rural settlement dispersion is particularly high in agricultural regions in south Hebei and southwest Shandong, suggesting rural settlement density keeps increasing from northeast to southwest, charac- terized by high density and dispersed spatial distribution in traditional agricultural regions. Furthermore, rural settlements show dramatic spatial differences in terms of distribution and dynamic change degrees in the Bohai Rim. In terms of spatial distribution, rural residential land is always extensive in plains, with a high density of rural settlements, on the North China Plain in particular, and rural residential land in the south of Shandong province is also exten- sive, with most rural settlement land use areas in the 5x5 km grid cells exceeding 3 km2. However, traditional agricultural regions have underdeveloped economies, industrialization and tertiary industries, characterized by low urbanization rates, with farmers not feeling as- similated in rural or urban areas. In terms of the temporal sequence, urban expansion rapidly promotes the transformation of rural residential lands in rural-urban transitional belts of pro- vincial capital or prefecture-level city into urban lands, and in traditional rural areas, residen- tial lands are growing. The natural environment, transportation conditions, economic devel- opment and farmers＇ incomes all have effects on type of land use change and pattern展开更多
Antimony(Sb) is a toxic metalloid, and its pollution has become a global environmental problem as a result of its extensive use and corresponding Sb-mining activities. The toxicity and mobility of Sb strongly depend o...Antimony(Sb) is a toxic metalloid, and its pollution has become a global environmental problem as a result of its extensive use and corresponding Sb-mining activities. The toxicity and mobility of Sb strongly depend on its chemical speciation. In this review, we summarize the current knowledge on the biogeochemical processes(including emission, distribution,speciation, redox, metabolism and toxicity) that trigger the mobilization and transformation of Sb from pollution sources to the surrounding environment. Natural phenomena such as weathering, biological activity and volcanic activity, together with anthropogenic inputs, are responsible for the emission of Sb into the environment. Sb emitted in the environment can adsorb and undergo redox reactions on organic or inorganic environmental media, thus changing its existing form and exerting toxic effects on the ecosystem. This review is based on a careful and systematic collection of the latest papers during 2010–2017 and our research results, and it illustrates the fate and ecological effects of Sb in the environment.展开更多
With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern Ch...With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic （165±5 Ma）, great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at -165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.展开更多
Background： Iliac vein compression syndrome （1VCS） is an important cause of deep vein thrombosis, but the incidence oflVCS is still unclear. The purpose of this prospective study was to determine the incidence of I...Background： Iliac vein compression syndrome （1VCS） is an important cause of deep vein thrombosis, but the incidence oflVCS is still unclear. The purpose of this prospective study was to determine the incidence of IVCS in an asymptomatic patient population and to evaluate the risk factors in patients with and without 1VCS. Methods： From October 2011 to November 2012, a total of 500 patients （228 women and 272 men; mean age of 55.4 ± 14.7 years） with no vascular-related symptoms were enrolled in this study. Computed tomography was performed to evaluate all patients. The degree of venous compression was calculated as the diameter of the common iliac vein at the site of maximal compression divided by the mean diameter of the uncompressed proximal and caudal left common iliac vein （LCIV）. We compared the stenosis rate of the common iliac vein in women and men according to age and followed up patients to evaluate outcomes. Results： The mean compression degree of the LCIV was 16% （4%, 36%）： 37.8% of patients had a compression degree ≥25% and 9.8% had a compression degree ≥50%. There was a significant difference between men and women in the LCIV compression degree （9% [3%, 30%] vs. 24% [8%, 42%]; U = 4.66, P 〈 0.01）. In addition, the LCIV compression degree among younger women （≤40 years） was significantly different compared with that in older women （〉40 years） （42% [31%, 50%] vs. 19% [5%, 39%]; U = 5.14, P 〈 0.001 ）. Follow-up was completed in 367 patients with a mean follow-up of 39.5 months （range, 6-56 months）. The incidence of IVCS in the follow-up period was 1.6%. Stenosis rate and the diameter of the site of maximal compression correlated with the incidence of IVCS. Multivariable Cox regression analysis showed that the stenosis rate was an independent risk factor of IVCS （Wald x2 = 8.84, hazard ratio = 1.13, P 〈 0.001 ）. Conclusions： The incidence of IVCS was low and correlated with the stenosis rate ofiliac vein. Preventative therapy may be warrante展开更多
The NOTCH gene was identified approximately 110 years ago.Classical studies have revealed that NOTCH signaling is an evolutionarily conserved pathway.NOTCH receptors undergo three cleavages and translocate into the nu...The NOTCH gene was identified approximately 110 years ago.Classical studies have revealed that NOTCH signaling is an evolutionarily conserved pathway.NOTCH receptors undergo three cleavages and translocate into the nucleus to regulate the transcription of target genes.NOTCH signaling deeply participates in the development and homeostasis of multiple tissues and organs,the aberration of which results in cancerous and noncancerous diseases.However,recent studies indicate that the outcomes of NOTCH signaling are changeable and highly dependent on context.In terms of cancers,NOTCH signaling can both promote and inhibit tumor development in various types of cancer.The overall performance of NOTCH-targeted therapies in clinical trials has failed to meet expectations.Additionally,NOTCH mutation has been proposed as a predictive biomarker for immune checkpoint blockade therapy in many cancers.Collectively,the NOTCH pathway needs to be integrally assessed with new perspectives to inspire discoveries and applications.In this review,we focus on both classical and the latest findings related to NOTCH signaling to illustrate the history,architecture,regulatory mechanisms,contributions to physiological development,related diseases,and therapeutic applications of the NOTCH pathway.The contributions of NOTCH signaling to the tumor immune microenvironment and cancer immunotherapy are also highlighted.We hope this review will help not only beginners but also experts to systematically and thoroughly understand the NOTCH signaling pathway.展开更多
AIM To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis,depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gas...AIM To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis,depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma.METHODS The expression of P16 protein was examined by streptavidin-peroxidase conjugated method (S-P); the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma.RESULTS Expression of P16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of P16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P＜0.05). The positive rate of P16 protein expression in mucoid carcinoma 10.00% (1/ 10) was significantly lower than that in poorly differentiated carcinoma 51.22% ( 21/ 41 ),undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/ 16) (P＜0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P＜0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas.CONCLUSIONS The expression loss of P16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.展开更多
Rural restructuring is a process of reshaping socio-economic morphology and spatial pattern in rural territory in response to the changes of elements both in kernel system and external system of rural development, by ...Rural restructuring is a process of reshaping socio-economic morphology and spatial pattern in rural territory in response to the changes of elements both in kernel system and external system of rural development, by optimally allocating and efficiently managing the material and non-material elements in the two systems. It aims at ultimately optimizing the structure and promoting the function within rural territorial system as well as realizing the coordination of structure and complementation of function between urban and rural territorial system. This paper establishes a theoretical framework of rural restructuring through elabo- rating the concept and connotations as well as analyzing the mechanism pushing forward rural restructuring based on the evolution of ＂elements-structure-function＂, and probes the approaches from the three aspects of spatial restructuring, economic restructuring and social restructuring. Besides, the authors argue that the study of rural restructuring in China in the future needs to focus on the aspects of long-term and multi-scale process and pattern, mechanism, regional models, rural planning technology system and standard, policy and institutional innovations concerning rural restructuring as well as the impacts of globalization on rural restructuring, in order to serve the current national strategic demands and cope with the changes of rural development elements in the process of urban-rural development transformation.展开更多
The core objective of rural vitalization is to systemically establish a coupling pattern of various rural development elements including population, land and industry. As one of the prerequisites, land resources is re...The core objective of rural vitalization is to systemically establish a coupling pattern of various rural development elements including population, land and industry. As one of the prerequisites, land resources is required to be optimally allocated via land consolidation. Consequently, land consolidation contributes greatly to population agglomeration, industrial development and resources support under the context of combating rural decline. Based on the key elements affecting rural development, this paper elaborates the connotation of rural vitalization and land consolidation in the new era as well as their relationships. Furthermore, the paper analyzes the alternative paths for achieving rural vitalization via land consolidation, and discusses the future directions of land consolidation and rural vitalization. The conclusions are drawn as follows:(1) To cope with the loss and decline of the intrinsic elements in rural areas, rural vitalization is a development strategy aimed at realizing economic, political, cultural and ecological rejuvenation in rural area by reshaping socio-economic morphology and spatial pattern in rural territory.(2) From the perspective of rural vitalization, land consolidation is endowed with new connotation, which should not only target at activating the key elements of rural development, but also place emphasis on coordinating material space and spirit core as well as integrating the restructuring of the physical space and the rural governance system.(3) Land consolidation should be compatible with regional natural conditions and the current stage of socio-economic development. According to the principle of regional planning and classification strategy, the appropriate models and paths should be adopted to promote the benign interactions of population, land and industry based on engineering techniques and ecological means.(4) Under the background of national strategy of rural vitalization, it is necessary to reshape the value orientation of land consolidation based on a scientific und展开更多
This paper reports geochemical and Pb-Sr-Nd isotopic compositions of the Indosinian Yangba (215 Ma),Nanyili (225 Ma) and Mopi granitoids from the Bikou block of the northwestern margin of the Yangtze plate. These gran...This paper reports geochemical and Pb-Sr-Nd isotopic compositions of the Indosinian Yangba (215 Ma),Nanyili (225 Ma) and Mopi granitoids from the Bikou block of the northwestern margin of the Yangtze plate. These granitoids are enriched in Al (Al2O3:14.56%―16.48%) and Sr (352 μg/g―1047 μg/g),and depleted in Y (<16 μg/g) and HREE (e.g. Yb<1.61 μg/g),resulting in high Sr/Y (36.3―150) and (La/Yb)N (7.8―36.3) ratios and strongly fractionationed REE patterns. The Indosinian granotoids show initial Sr isotopic ratios (ISr) from 0.70419 to 70752,εNd(t) values from-3.1 to -8.5,and initial Pb isotopic ratios 206Pb/204Pb=17.891-18.250,207Pb/204Pb=15.494-15.575,and 208Pb/204Pb=37.788-38.335. Their geochemi-cal signatures indicate that the granitoids are adakitic. However,they are distinct from some adakites,generated by partial melting of subducted oceanic slab and/or underplated basaltic lower crust,be-cause they have high K (K2O: 1.49%―3.84%) and evolved Nd isotopic compositions,with older Nd iso-topic model ages (TDM=1.06―1.83 Ga). Geochemical and Sr-Nd isotopic compositions suggest that the magmas of the Insoninian adakitic rocks in the Bikou block were derived from partial melting of thick-ened basaltic lower crust. Combined with regional analyses,a lithospheric delamination model after collision between the North China and South China plates can account for the Indosinian adakitic magma generation. On the other hand,based on the Pb-Sr-Nd isotopic probing to the magma sources of the adakitic rocks,it is suggested that there is an unexposed continent-type basement under the exposed Bikou Group volcanic rocks. This can constrain on the Bikou Group volcanic rocks not to be MORB-or OIB-type.展开更多
Zircons were separated from granitoids, gneisses, and sedimentary rocks of the Chinese Altai. Those with igneous characteristics yielded U-Pb ages of 280-2800 Ma, recording a long history of magmatic activity in the r...Zircons were separated from granitoids, gneisses, and sedimentary rocks of the Chinese Altai. Those with igneous characteristics yielded U-Pb ages of 280-2800 Ma, recording a long history of magmatic activity in the region. Zircon Hf isotopic compositions show an abrupt change at ~420 Ma, indicating that prior to that time the magmas came from both ancient and juvenile sources, whereas younger magmas were derived mainly from juvenile material. This may imply that the lithosphere was signifi- cantly modified in composition by a rapid addition of melt from the mantle. We suggest that this dramatic change was due to the onset of ridge subduction, which can account not only for the formation of voluminous granitoids, mafic rocks with complex compositions, and the association of adakite + high-Mg andesite + boninite + Nb-enriched basalt, but also for the coeval high-T, low-P metamorphism.展开更多
基金National Natural Science Foundation of China,No.41171149No.41130748No.41201176
文摘The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform, due to long-term existed ＂dual-track＂ structure of rural-urban development in China as well as un- stable rural development institution and mechanism. It is necessary to restructure rural pro- duction, living and ecological space by carrying out land consolidation, so as to establish a new platform for building new countryside and realizing urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring. Basing on the effects analysis of industrialization and urbanization on rural production, living and ecological space, the mechanism of pushing forward rural spatial restructuring by carry- ing out land consolidation is probed. A conceptualization of the models of rural production, living and ecological spatial restructuring is analyzed combining with agricultural land con- solidation, hollowed villages consolidation and industrial and mining land consolidation. Fi- nally, the author argues that a ＂bottom-up＂ restructuring strategy accompanied by a few ＂top-down＂ elements is helpful for smoothly pushing forward rural spatial restructuring in China. In addition, the optimization and restructuring of rural production, living and ecological space will rely on the innovations of regional engineering technology, policy and mechanism, and mode of rural land consolidation, and more attentions should be paid to rural space, the foundation base and platform for realizing urban-rural integration development.
基金National Natural Science Foundation of China, No.40635029 No.40871257+1 种基金 Knowledge Innovation Program of the Chinese Academy of Sciences, No.KSCX-YW-09 No.KZCX2-YW-QN304
文摘Rural hollowing is a recent geographic phenomenon that has received significant attention in China, which is experiencing rapid urbanization. It has led to the wasteful use of rural land resources, and imposed obstacles on the optimization of land use and coordinated urban-rural development. Rural hollowing has various forms of manifestation, which refers to the neglect and vacancy of rural dwellings, both of which can lead to damage and ultimate abandonment of rural dwellings. Damaged dwellings have different degrees of destruction, ranging from slight, moderate to severe. The evolutive process of rural hollowing in general has five stages, i.e., emergence, growth, flourishing, stability, and decline. Based on the combination of both regional economic development level and its physiographic features, the types of rural hollowing can be categorised as urban fringe, plain agricultural region, hilly agricultural region, and agro-pastoral region. Especially, the plain agricultural region is the most typical one in rural hollowing, which shows the spatial evolution of rural hollowing as a ＂poached egg＂ pattern with a layered hollow core and solid shape. Furthermore, the driving forces behind rural hollowing are identified as the pull of cities and push of rural areas. In particular, this paper identifies contributors to rural hollowing that include rural depopulation in relation to rapid urbanisation and economic change, land ownership and land use policy, and institutional barriers.
基金National Natural Science Foundation of China, No.40635029 No.40771014
文摘Based on the acquaintance of the regional background of urban-rural transformational development and investigations on the spot,this paper discusses the holistic situation, dominant factors and mechanism of arable land loss and land for construction occupation in the coastal area of China over the last decade,with the aid of GIS technology.Conclusions of the research are summarized as follows：（1）the arable land had been continuously decreasing from 1996 to 2005,with a loss of 1,708,700 hm^2 and an average decrement of 170,900 hm^2 per year;（2）land for construction increased 1,373,700 hm^2 ,with an average increment of 153,200 hm^2 per year;（3）total area of encroachment on arable land for construction between 1996 and 2005 was 1,053,100 hm^2 ,accounting for 34.03%of the arable land loss in the same period,the percentages of which used for industrial land（INL）,transportation land（TRL）,rural construction land（RUL）and town construction land（TOL）are 45.03%,15.8%,15.47%and 11.5%,respectively;and（4）the fluctuation of the increase of construction land and encroachment on arable land in the area were deeply influenced by the nation＇s macroscopic land-use policies and development level of regional economy.The growth of population and advancement of technology promoted the rapid industrialization, construction of transportation infrastructures,rural urbanization and expansion of rural settlements in the eastern coastal area,and therefore were the primary driving forces of land-use conversion.
基金Surported by the Funds of Hundred Outsdanding Persons project of Shanghai(97BR029)Science and Technology Commission of Shanghai(984419067)
文摘AIM: To compare the therapeutic effect and significances of multimodality treatment for hepatocellular carcinoma (HCC) with tumor thrombi in portal vein (PVTT). METHODS: HCC patients (n=147) with tumor thrombi in the main portal vein or the first branch of portal vein were divided into four groups by the several therapeutic methods. There were conservative treatment group in 18 out of patients (group A); and hepatic artery ligation(HAL) and/or hepatic artery infusion (HAI) group in 18 patients (group B), in whom postoperative chemoembolization was done periodically; group of removal of HCC with PVTT in 79 (group C) and group of transcatheter hepatic arterial chemoembolization (TACE) or HAI and/or portal vein infusion (PVI) after operation in 32 (group D). RESULTS: The median survival period was 12 months in our series and the 1-,3-, and 5-year survival rates were 44.3%, 24.5% and 15.2%, respectively. The median survival times were 2, 5, 12 and 16 months in group A, B, C and D, respectively. The 1-, 3- and 5-year survival rates were 5.6%, 0% and 0% in group A; 22.2%, 5.6% and 0% in group B; 53.9%, 26.9% and 16.6% in group C; 79.3%, 38.9% and 26.8% in group D, respectively. Significant difference appeared in the survival rates among the groups (P 【 0.05). CONCLUSION: Hepatic resection with removal of tumor thrombi and HCC should increase the curative effects and be encouraged for the prolongation of life span and quality of life for HCC patients with PVTT, whereas the best therapeutic method for HCC with PVTT is with regional hepatic chemotherapy or chemoembolization after hepatic resection with removal of tumor thrombi.
文摘An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12^th, 2008 and resulted in long surface ruptures （〉300 km）. The first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co-seismic vertical displacements along the individual fault of the Yingxiu-Beiehuan rupture zone reach 2.514 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5-6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2-3 m dextral strike-slip component. The Wenchuan thrust-faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.
基金supported by the National Natural Science Foundation of China(7177121671701209)
文摘Artificial bee colony(ABC) is one of the most popular swarm intelligence optimization algorithms which have been widely used in numerical optimization and engineering applications. However, there are still deficiencies in ABC regarding its local search ability and global search efficiency. Aiming at these deficiencies,an ABC variant named hybrid ABC(HABC) algorithm is proposed.Firstly, the variable neighborhood search factor is added to the solution search equation, which can enhance the local search ability and increase the population diversity. Secondly, inspired by the neuroscience investigation of real honeybees, the memory mechanism is put forward, which assumes the artificial bees can remember their past successful experiences and further guide the subsequent foraging behavior. The proposed memory mechanism is used to improve the global search efficiency. Finally, the results of comparison on a set of ten benchmark functions demonstrate the superiority of HABC.
基金This work was supported by the Outstanding Young Scientist Program of the National Natural Science Foundation of China (Grant No. 39925024).
文摘Field survey and greenhouse experiments were carried out to identify and characterize zinc (Zn) uptake and accumulation by a new Zn hyperaccumulating plant species (Sedum alfredii Hance) native to China. Zinc concentration in the shoots of Sedum alfredii Hance grown on an ancient mined area ranged from 4134 to 5000 mg/kg, with a mean of 4515 mg/kg. It suggests that Sedum alfredii could not only grow on heavily Pb/Zn contaminated soils, but also could accumulate extraordinarily high concentration of Zn. Under nutrient solution culture conditions, Sedum alfredii Hance grew healthy at Zn supplying levels from 0.006 to 240 mg · L-1. Zinc concentration in the shoots increased with external Zn levels increasing. The Zn concentration and accumulation in the shoots reached the highest at Zn supply level of SO mg/L, with 19.67 g/kg and 19.83 nig/plant, respectively. All the results showed that Sedum alfredii Hance is a new Zn hyperaccumulating plant. This provides a new plant material to explore mechanism of
基金National Natural Science Foundation of China, No.41171149 No.41130748 Knowledge Innovation Program of the Chinese Academy of Sciences, No.KZCX2-YW-QN304
文摘Land use transition refers to the changes in land use morphology （both dominant morphology and recessive morphology） of a certain region over a certain period of time driven by socio-economic change and innovation, and it usually corresponds to the transition of socio-economic development phase. In China, farmland and rural housing land are the two major sources of land use transition. This paper analyzes the spatio-temporal coupling characteristics of farmland and rural housing land transition in China, using high-resolution Landsat TM （Thematic Mapper） data in 2000 and 2008, and the data from the Ministry of Land and Resources of China. The outcomes indicated that： （1） during 2000-2008, the correlation coefficient of farmland vs. rural housing land change is -0.921, and it shows that the change pattern of farmland and rural housing land is uncoordinated; （2） the result of Spearman rank correlation analysis shows that rural housing land change has played a major role in the mutual transformation of farmland and rural housing land; and （3） it shows a high-degree spatial coupling between farmland and rural housing land change in southeast China during 2000-2008. In general, farmland and rural housing land transition in China is driven by socio-economic, bio-physical and managerial three-dimensional driving factors through the interactions among rural population, farmland and rural housing land. However, the spatio-temporal coupling phenomenon and mechanism of farmland and rural housing land transition in China are largely due to the ＂dual-track＂ structure of rural-urban development.
基金National Natural Science Foundation of China, No. 41401190 No.41130748 No.41101165
文摘Based on multiple remote-sensing image interpretation and classification, and economic and social data, this study focused on rural settlement and land use change amidst rapid urbanization. Rural settlements, spatial and temporal patterns of land use and influ- encing factors in the Bohai Rim were explored within 5x5 km grid cells, as per GIS spatial analysis and geostatistical analysis. Results show that the spatial distribution of rural settle- ments in the Bohai Rim is remarkably varied. The number of rural settlement sites in a 5x5 km grid cell exceeding 5.0 are distributed in a six-area pattern in the Bohai Rim; rural settlement dispersion is particularly high in agricultural regions in south Hebei and southwest Shandong, suggesting rural settlement density keeps increasing from northeast to southwest, charac- terized by high density and dispersed spatial distribution in traditional agricultural regions. Furthermore, rural settlements show dramatic spatial differences in terms of distribution and dynamic change degrees in the Bohai Rim. In terms of spatial distribution, rural residential land is always extensive in plains, with a high density of rural settlements, on the North China Plain in particular, and rural residential land in the south of Shandong province is also exten- sive, with most rural settlement land use areas in the 5x5 km grid cells exceeding 3 km2. However, traditional agricultural regions have underdeveloped economies, industrialization and tertiary industries, characterized by low urbanization rates, with farmers not feeling as- similated in rural or urban areas. In terms of the temporal sequence, urban expansion rapidly promotes the transformation of rural residential lands in rural-urban transitional belts of pro- vincial capital or prefecture-level city into urban lands, and in traditional rural areas, residen- tial lands are growing. The natural environment, transportation conditions, economic devel- opment and farmers＇ incomes all have effects on type of land use change and pattern
基金supported by the National Natural Science Foundation of China (Nos.21477008,21677014,U1706217)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No.51721093)the Interdiscipline Research Funds of Beijing Normal University (No.312231103)
文摘Antimony(Sb) is a toxic metalloid, and its pollution has become a global environmental problem as a result of its extensive use and corresponding Sb-mining activities. The toxicity and mobility of Sb strongly depend on its chemical speciation. In this review, we summarize the current knowledge on the biogeochemical processes(including emission, distribution,speciation, redox, metabolism and toxicity) that trigger the mobilization and transformation of Sb from pollution sources to the surrounding environment. Natural phenomena such as weathering, biological activity and volcanic activity, together with anthropogenic inputs, are responsible for the emission of Sb into the environment. Sb emitted in the environment can adsorb and undergo redox reactions on organic or inorganic environmental media, thus changing its existing form and exerting toxic effects on the ecosystem. This review is based on a careful and systematic collection of the latest papers during 2010–2017 and our research results, and it illustrates the fate and ecological effects of Sb in the environment.
文摘With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic （165±5 Ma）, great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at -165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.
文摘Background： Iliac vein compression syndrome （1VCS） is an important cause of deep vein thrombosis, but the incidence oflVCS is still unclear. The purpose of this prospective study was to determine the incidence of IVCS in an asymptomatic patient population and to evaluate the risk factors in patients with and without 1VCS. Methods： From October 2011 to November 2012, a total of 500 patients （228 women and 272 men; mean age of 55.4 ± 14.7 years） with no vascular-related symptoms were enrolled in this study. Computed tomography was performed to evaluate all patients. The degree of venous compression was calculated as the diameter of the common iliac vein at the site of maximal compression divided by the mean diameter of the uncompressed proximal and caudal left common iliac vein （LCIV）. We compared the stenosis rate of the common iliac vein in women and men according to age and followed up patients to evaluate outcomes. Results： The mean compression degree of the LCIV was 16% （4%, 36%）： 37.8% of patients had a compression degree ≥25% and 9.8% had a compression degree ≥50%. There was a significant difference between men and women in the LCIV compression degree （9% [3%, 30%] vs. 24% [8%, 42%]; U = 4.66, P 〈 0.01）. In addition, the LCIV compression degree among younger women （≤40 years） was significantly different compared with that in older women （〉40 years） （42% [31%, 50%] vs. 19% [5%, 39%]; U = 5.14, P 〈 0.001 ）. Follow-up was completed in 367 patients with a mean follow-up of 39.5 months （range, 6-56 months）. The incidence of IVCS in the follow-up period was 1.6%. Stenosis rate and the diameter of the site of maximal compression correlated with the incidence of IVCS. Multivariable Cox regression analysis showed that the stenosis rate was an independent risk factor of IVCS （Wald x2 = 8.84, hazard ratio = 1.13, P 〈 0.001 ）. Conclusions： The incidence of IVCS was low and correlated with the stenosis rate ofiliac vein. Preventative therapy may be warrante
基金the National Natural Science Foundation of China(No.62131009,82072597,81874120,and 82073370).
文摘The NOTCH gene was identified approximately 110 years ago.Classical studies have revealed that NOTCH signaling is an evolutionarily conserved pathway.NOTCH receptors undergo three cleavages and translocate into the nucleus to regulate the transcription of target genes.NOTCH signaling deeply participates in the development and homeostasis of multiple tissues and organs,the aberration of which results in cancerous and noncancerous diseases.However,recent studies indicate that the outcomes of NOTCH signaling are changeable and highly dependent on context.In terms of cancers,NOTCH signaling can both promote and inhibit tumor development in various types of cancer.The overall performance of NOTCH-targeted therapies in clinical trials has failed to meet expectations.Additionally,NOTCH mutation has been proposed as a predictive biomarker for immune checkpoint blockade therapy in many cancers.Collectively,the NOTCH pathway needs to be integrally assessed with new perspectives to inspire discoveries and applications.In this review,we focus on both classical and the latest findings related to NOTCH signaling to illustrate the history,architecture,regulatory mechanisms,contributions to physiological development,related diseases,and therapeutic applications of the NOTCH pathway.The contributions of NOTCH signaling to the tumor immune microenvironment and cancer immunotherapy are also highlighted.We hope this review will help not only beginners but also experts to systematically and thoroughly understand the NOTCH signaling pathway.
基金the grant from the Teaching Committee of HunanProvince,No.97B095the"8th 5-year Plan"of Health Department of Hunan Province,No.9301
文摘AIM To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis,depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma.METHODS The expression of P16 protein was examined by streptavidin-peroxidase conjugated method (S-P); the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma.RESULTS Expression of P16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of P16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P＜0.05). The positive rate of P16 protein expression in mucoid carcinoma 10.00% (1/ 10) was significantly lower than that in poorly differentiated carcinoma 51.22% ( 21/ 41 ),undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/ 16) (P＜0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P＜0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas.CONCLUSIONS The expression loss of P16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.
基金The Bagui Scholars Program of Guangxi Zhuang Autonomous Region National Natural Science Foundation of China, No.41571166
文摘Rural restructuring is a process of reshaping socio-economic morphology and spatial pattern in rural territory in response to the changes of elements both in kernel system and external system of rural development, by optimally allocating and efficiently managing the material and non-material elements in the two systems. It aims at ultimately optimizing the structure and promoting the function within rural territorial system as well as realizing the coordination of structure and complementation of function between urban and rural territorial system. This paper establishes a theoretical framework of rural restructuring through elabo- rating the concept and connotations as well as analyzing the mechanism pushing forward rural restructuring based on the evolution of ＂elements-structure-function＂, and probes the approaches from the three aspects of spatial restructuring, economic restructuring and social restructuring. Besides, the authors argue that the study of rural restructuring in China in the future needs to focus on the aspects of long-term and multi-scale process and pattern, mechanism, regional models, rural planning technology system and standard, policy and institutional innovations concerning rural restructuring as well as the impacts of globalization on rural restructuring, in order to serve the current national strategic demands and cope with the changes of rural development elements in the process of urban-rural development transformation.
基金Key Program of National Natural Science Foundation of China,No.41731286The Postdoctoral Science Foundation of China,No.2018M630197The Bagui Scholars Program of Guangxi Zhuang Autonomous Region.
文摘The core objective of rural vitalization is to systemically establish a coupling pattern of various rural development elements including population, land and industry. As one of the prerequisites, land resources is required to be optimally allocated via land consolidation. Consequently, land consolidation contributes greatly to population agglomeration, industrial development and resources support under the context of combating rural decline. Based on the key elements affecting rural development, this paper elaborates the connotation of rural vitalization and land consolidation in the new era as well as their relationships. Furthermore, the paper analyzes the alternative paths for achieving rural vitalization via land consolidation, and discusses the future directions of land consolidation and rural vitalization. The conclusions are drawn as follows:(1) To cope with the loss and decline of the intrinsic elements in rural areas, rural vitalization is a development strategy aimed at realizing economic, political, cultural and ecological rejuvenation in rural area by reshaping socio-economic morphology and spatial pattern in rural territory.(2) From the perspective of rural vitalization, land consolidation is endowed with new connotation, which should not only target at activating the key elements of rural development, but also place emphasis on coordinating material space and spirit core as well as integrating the restructuring of the physical space and the rural governance system.(3) Land consolidation should be compatible with regional natural conditions and the current stage of socio-economic development. According to the principle of regional planning and classification strategy, the appropriate models and paths should be adopted to promote the benign interactions of population, land and industry based on engineering techniques and ecological means.(4) Under the background of national strategy of rural vitalization, it is necessary to reshape the value orientation of land consolidation based on a scientific und
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40234052 and 40521001)the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT0441)
文摘This paper reports geochemical and Pb-Sr-Nd isotopic compositions of the Indosinian Yangba (215 Ma),Nanyili (225 Ma) and Mopi granitoids from the Bikou block of the northwestern margin of the Yangtze plate. These granitoids are enriched in Al (Al2O3:14.56%―16.48%) and Sr (352 μg/g―1047 μg/g),and depleted in Y (<16 μg/g) and HREE (e.g. Yb<1.61 μg/g),resulting in high Sr/Y (36.3―150) and (La/Yb)N (7.8―36.3) ratios and strongly fractionationed REE patterns. The Indosinian granotoids show initial Sr isotopic ratios (ISr) from 0.70419 to 70752,εNd(t) values from-3.1 to -8.5,and initial Pb isotopic ratios 206Pb/204Pb=17.891-18.250,207Pb/204Pb=15.494-15.575,and 208Pb/204Pb=37.788-38.335. Their geochemi-cal signatures indicate that the granitoids are adakitic. However,they are distinct from some adakites,generated by partial melting of subducted oceanic slab and/or underplated basaltic lower crust,be-cause they have high K (K2O: 1.49%―3.84%) and evolved Nd isotopic compositions,with older Nd iso-topic model ages (TDM=1.06―1.83 Ga). Geochemical and Sr-Nd isotopic compositions suggest that the magmas of the Insoninian adakitic rocks in the Bikou block were derived from partial melting of thick-ened basaltic lower crust. Combined with regional analyses,a lithospheric delamination model after collision between the North China and South China plates can account for the Indosinian adakitic magma generation. On the other hand,based on the Pb-Sr-Nd isotopic probing to the magma sources of the adakitic rocks,it is suggested that there is an unexposed continent-type basement under the exposed Bikou Group volcanic rocks. This can constrain on the Bikou Group volcanic rocks not to be MORB-or OIB-type.
基金Supported by National Basic Research Program of China (Grant No. 2007CB411308)Hong Kong RGC Grants (Grant Nos. HKU704307P and 704004P)+1 种基金National Natural Science Foundation of China (Grant Nos. 40772130, 40803009)CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Zircons were separated from granitoids, gneisses, and sedimentary rocks of the Chinese Altai. Those with igneous characteristics yielded U-Pb ages of 280-2800 Ma, recording a long history of magmatic activity in the region. Zircon Hf isotopic compositions show an abrupt change at ~420 Ma, indicating that prior to that time the magmas came from both ancient and juvenile sources, whereas younger magmas were derived mainly from juvenile material. This may imply that the lithosphere was signifi- cantly modified in composition by a rapid addition of melt from the mantle. We suggest that this dramatic change was due to the onset of ridge subduction, which can account not only for the formation of voluminous granitoids, mafic rocks with complex compositions, and the association of adakite + high-Mg andesite + boninite + Nb-enriched basalt, but also for the coeval high-T, low-P metamorphism.
