The Effect of ENSO on Hydrological Structure and Environment in the South Central Coast-Vietnam

ENSO(El Niño-Southern Oscillation)phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general.In case of Vietnamese South-Central Waters,impacts of ENSO only focused on issues of changing seasonal wind,seawater temperature anomalies,changing of water masses as the air-sea interaction.Based on several data sets collecting in the period of 2003-2017,new finding of seawater temperature,salinity and environmental factors was identified in the water masses of Vietnamese South-Central Waters.The highest salinity was 35.4‰.During the El Nino event,increasing water temperature and salinity caused to move the deeper water masses to be closer to the sea surface than that initial depth in the neutral period.During the La Nina event,the temperature of most water masses reduced by 0.1-3.0℃,and then these water masses could be affected to the deeper layer.During the phase from strong ENSO event towards the neutral time,nutrient salts of the 4 water masses were lower concentration in the neutral year,causing the lack of phosphorus in sea surface water masses.

Mechanism of Structure Variations at Rifted Margins in the Central Segment of South Atlantic:Insights from Numerical Modeling

Rifted margins in the central South Atlantic portray spatial variability in terms of preserved width and thickness,which relates to complex rift-related fault activities.However,there is still a lack of systematic and quantitative explanations for the causes of the variations that are observed along the paired rifts.To elucidate this issue,2D viscous-plastic thermomechanical numerical models are applied to capture the behavior of deformation,in which we investigate the effects of extensional rate,crustal strength and thickness on crust-mantle coupling,and timing of transition from rifting to breakup.Our numerical experiments demonstrate that crust-mantle decoupling accounts for crustal hyperextension,and that incorporating moderate-intensity rheology into lower crust may yield insights into the hyper-extended crust and asymmetric architecture observed in the central South Atlantic.The results also suggest that undulations in lithospheric basement cause asymmetric mantle upwelling.The lower crust of fold belts takes priority to be thermally weakened over craton and induces rift migration simultaneously.A new mechanism for the formation of failed rift is described,where the mechanical decoupling derived from thermally weakened lower crust gives access to dual rift migration.These results reinforce the interpretation on how crustal rheology shapes margins architectures and highlight the first-order effects of crust-mantle coupling.

Fluid Inclusion Geochemistry of Metallic Ore Deposits in the South- Central Sector of theDa Hinggan Mountains in China

Physicochemical parameters of mineralization such as temperature, pressure, salinity, density, composition and boiling of ore fluids as well as pH, Eh, fo2 and reducing parameter in theprocess of mineralization of major ore deposits in the study district have been obtained by the authors through systematic observation and determination of characteristics and phase changes of fluid inclusions at different temperatures and analysis of gaseous and liquid phase compositions of the inclusions, thus providing a scientific basis for the division of mineralization-alteration stages, types of mineral deposits and minerogenetic series and the deepening of the knowledge about the ore-forming processes and mechanisms of mineral deposits. It is indicated that the deposits of the same type have similar fluid inclusion geochemical features and physicochemical parameters though they belong to different minerogenetic series, while the compositions of inclusions are not conditioned by deposit types but closely related to the minerogenetic series of deposits.

Seasonal and annual variations of marine sinking particulate flux during 1993 ~ 1996 in the central South China Sea

A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993 ~ 1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species （ Globigerinoides sacculifer , G. ruber , Globigerinita glutinata, Neogloboquadrina dutertrei ） and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution.

Petrogenesis and Tectonic Significance of Carboniferous Granites on the North Side of the Solonker Suture,Central South Mongolia

The central part of South Mongolia,located to the north of the Solonker Suture,is a key region for studying the late Paleozoic tectonic evolution of the Central Asian Orogenic Belt(CAOB).Voluminous late Paleozoic granitic rocks,especially of Carboniferous age,were intruded in this area.However,these granitoids have not been well studied and there is a lack of precise ages and isotopic data.This has hampered our understanding of the tectonic evolution of southeastern Mongolia,and even the entire CAOB.In this paper,we provide new U-Pb isotopic ages and geochemical analyses for these Carboniferous granites.One granite from the Ulaanbadrakh pluton yielded a zircon U-Pb age of 326 Ma,which indicates emplacement in the Early Carboniferous,and three other granites from the Khatanbulag region gave zircon U-Pb ages of 316 Ma,315 Ma,and 311 Ma,which indicate emplacement in the Late Carboniferous.The Early Carboniferous granite has SiO2 contents of 70.04–70.39 wt%and K_(2)O+Na_(2)O contents of 6.48–6.63 wt%,whereas the Late Carboniferous granites have more variable compositions(SiO2=65.29–77.91 wt%and K2O+Na2O=5.30–7.27 wt%).All the granites are weakly-peraluminous I-types that are relatively enriched in U,Th,K,Zr,Hf,and LREEs.The whole rock Sr-Nd and zircon in situ Lu-Hf isotope analyses for the Early Carboniferous granite gave positive values ofεNd(t)(2.87)andεHf(t)(4.31–12.37)with young Nd(TDM=860 Ma)and Hf(TDMc=1367–637 Ma)two-stage model ages,indicating derivation from juvenile crustal material.In contrast,the Late Carboniferous granites had more diverse values ofεNd(t)(–4.03 to 2.18)andεHf(t)(–12.69 to 5.04)with old Nd(TDM=1358–1225 Ma)and Hf(TDMc=2881–1294 Ma)depleted mantle two-stage model ages,suggesting derivation from remelting of Precambrian basement.Based on the existing results,the tectonic setting of the Late Carboniferous granites in the central part of South Mongolia is known for its diversity,and this paper believes that the tectonic background of the carboniferous granite records the tectonic transition from a continental-margin-arc to a postcollisional extensional setting during the Late Carboniferous–Permian.

Research of the Conductive Structure of Crust and the Upper Mantle beneath the South-Central Tibetan Plateau

With the super-wide band magnetoteiluric sounding data of the JUong （吉隆）-Cuoqin （措勤） profile （named line 800） which was completed in 2001 and the Dingri （定日）-Cuomai （措迈） profile （named line 900） which was completed in 2004, we obtained the strike direction of each MT station by strike analysis, then traced profiles that were perpendicular to the main strike direction, and finally obtained the resistivity model of each profile by nonlinear conjugate gradients （NLCG） inversion. With these two models, we described the resistivity structure features of the crust and the upper mantle of the center-southern Tibetan plateau and its relationship with Yalung Tsangpo suture： the upper crust of the research area is a resistive layer with resistivity value range of 200-3 000 Ω.m. The depth of its bottom surface is about 15-20 km generally, but the bottom surface of resistive layer is deeper in the middle of these two profiles. At llne 900, it is about 30 km deep, and even at line 800, it is about 38 km deep. There is a gradient belt of resistivity at the depth of 15-45 km, and a conductive layer is beneath it with resistivity even less than 5 Ω.m. This conductive layer is composed of individual conductive bodies, and at the south of the Yalung Tsangpo suture, the conductive bodies are smaller with thickness about 10 km and lean to the north slightly. However, at the north of the Yalung Tsangpo suture, the conductive bodies are larger with thickness about 30 km and also lean to the north slightly. Relatively, the conductive bodies of line 900 are thinner than those of line 800, and the depth of the bottom surface of line 900 is also shallower. At last, after analyzing the effect factors to the resistivity of rocks, it was concluded that the very conductive layer was caused by partial melt or connective water in rocks. It suggests that the middle and lower crust of the center-southern Tibetan plateau is very thick, hot, flabby, and waxy.

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Causes of the Extreme Hot Midsummer in Central and South China during 2017:Role of the Western Tropical Pacific Warming

This study investigates why an extreme hot midsummer occurred in Central and South China(CSC) during 2017. It is shown that the western North Pacific subtropical high(WNPSH) was abnormally intensified and westward-extending,resulting in anomalous high pressure and consequent extreme heat over CSC. The abnormal WNPSH was favored by the warming of the western tropical Pacific(WTP), which was unrelated to ENSO and manifested its own individual effect.The WTP warming enhanced the convection in-situ and led to anomalous high pressure over CSC via a local meridional circulation. The influence of the WTP was confirmed by CAM4 model experiments. A comparison between the 2017 midsummer and 2010 midsummer(with a stronger WNPSH but weaker extreme heat) indicated that the influence of the WNPSH on extreme heat can be modulated by the associated precipitation in the northwestern flank.The role of the WTP was verified by regression analyses on the interannual variation of the WTP sea surface temperature anomaly(SSTA). On the other hand, the WTP has undergone prominent warming during the past few decades, resulting from decadal to long-term changes and favoring extreme warm conditions. Through a mechanism similar to the interannual variation, the decadal to long-term changes have reinforced the influence of WTP warming on the temperature over CSC,contributing to the more frequent hot midsummers recently. It is estimated that more than 50% of the temperature anomaly over CSC in the 2017 midsummer was due to the WTP warming, and 40% was related to the decadal to long-term changes of the WTP SSTA.

Study on the Characteristics of Urban Air Pollution Based on Correspondence Analysis--A Case Study of Six Provincial Capitals in Central-south China

[Objective] The aim was to study the characteristics of urban air pollution on the basis of correspondence analysis.[Method] By using the correlated data from China Statistical Yearbook in 2010,a correspondence analysis on the air pollution indicators(like respirable particles,SO2 and NO2) of six provincial capitals in central-south China was carried out by means of SPSS software,and the characteristics of air pollution in the cities of China during different industrialization stages were summarized further.[Result] In the cities during early industrialization(like Nanning City and Guiyang City) and mineral resource-based cities(like Taiyuan City),the air was mainly polluted by SO2;for the cities in the middle industrialization(such as Changsha City,Wuhan City,Zhengzhou City and Chengdu City),the air was polluted by respirable particles chiefly;in the cities in late industrialization(like Guangzhou City and Shenzhen City) or completing industrialization(like Shanghai City),the air was mainly polluted by NO2;for the cities in pre-industrial stage(like Haikou City and Lhasa City),the characteristic of air pollution wasn’t obvious.[Conclusion] The study could provide references for the control of urban air pollution in China in the further.

Journal of Central South University of Technology

1 Aims and scope Central South University (CSU) is one of Chinese key universities, which is affiliated with the Ministry of Education. 'Journal of Central South University of Technology' (ISSN 1005-9784, CODEN JCSTFT) is sponsored by CSU.

The difference analysis of physical-mechanical properties of sediments in the central South Yellow Sea and Zhe-Min coastal area in China

The difference analysis of physical-mechanical properties of muddy sediments is made in the central South Yellow Sea and the Zhe-Min（Zhejiang Province to Fujian Province of China） coastal area. The results show that sediments in the two regions are both dominated by mud. There are perfect negative power function correlations between the water content and the density, the compression coefficient and the compression modulus; a good positive power function correlation between the liquid limit and the plastic limit, a perfect positive linear correlation between the water content and the void ratio, and a perfect polynomial function correlation between the miniature vane shear strength and the pocket penetration resistance. In general, compared with sediments in the Zhe-Min coastal area, sediments in the central South Yellow Sea possess high water content, high void ratio,low density, high plasticity, high compressibility, low shear strength. The causes of the differences between physical-mechanical properties of sediments are analyzed from the topographic features, material sources,hydrodynamic conditions, deposition rate, and material composition. Compared with the Zhe-Min coastal area,the central South Yellow Sea is far from the Mainland and low-lying; has poor hydrodynamic condition; the materials diffused to the area are less and dominated by fine clay, have the high content of smectite and organic matters. These factors lead to sediments of the central South Yellow Sea has the higher water content, the higher plasticity, the lower density, and the lower strength than sediments in the Zhe-Min coastal area.

Characteristics of seismic reflections in central region of the South China Sea and their geological significance

More than 4 000 km 48-channel seismic reflection data from the central region of the South China Sea have been interpreted. Five seismic interfaces have been distinguished, named T1, T2, T4, T6 and Tg respectively Meanwhile, five seismic sequences numbered I - V have been divided with the ages of Quaternary and Pliocene, Later Mocene, Earlier and Middle Miocene, Oligocene and Pre- Oligocene separately. Sequences I-II overlie all parts of the area. In the continental slope and island slope, Sequences III-V are mainly found in the grabens. Sequence III is found at moot profiles of the deep-sea basin, and Sequnce IV is seen not only at the margins of the east subbasin but also at the margins of the southwest subbasin. Strong reflection from Moho is found at most profiles of the deep-sea basin. The depth of Moho varies between 10 and 12 km, with a thickness of 6- 8 km for the crust. Calculated by age-basement depth correlation formula, the age of basaltic basement in the southwest subbasin is 51-39 Ma. It is indicated that the evolution of the southwest subbasin is simultaneous with or earlier than that of the east subbasin.

Southward surface flow in the central South Pacific

A large-scale surface flow with a southward component is proposed for the central South Pacific Ocean based on an interpretation of existing closely spaced and accurately measured temperatures and salinities along two latitudes in two different southern hemisphere winters: 28o S (Scorpio) and five degrees south of that (WOCE). Such a southward flow is not predicted from theory nor is it shown on current charts and globes. The observed longitudinal maximum in surface temperature along 28o S is centered around 130o W and has an amplitude of at least 5o C and an east/west range of about 60o of longitude. This striking feature is most easily explained by horizontal transport from latitudes closer to the equator. Since temperature atlases show that equatorial surface temperatures are always highest in the west, the origin of the warm water probably is toward the western side of the ocean as well. Thus the surface flow surrounding the longitudinal temperature maximum should be directed to the southeast. Where the surface temperatures are maximum the mixed layer depths are relatively large in a convex downward lens with maximum depths of 100 m;a correlation that is consistent with warm water moving south and being cooled from above. Salinities are maximum near the temperature maximum, also suggesting that the source of the surface flow is at low latitudes, where evaporation is usually expected to exceed precipitation. It is conjectured that the large-scale southeastward flow of the South Pacific is the analogue of the northeastward wide warm current off California documented over 30 years ago.

Anomalies of geophysical field in deep crustand earthquakes in Central-South Shanxi

Comprehensive studies on the crustal structures, the anomalies of geophysical field and the seismicity in Central-South Shanxi are conducted. The research results show that there are deep tectonic background for occurring moderate earthquakes in Lingshi-Jiexiu region between Linfen and Taiyuan. From now on, the region should be attached closely.

Helium-argon isotopic tracing for the Pb-Zn-Ag polymetallic ore deposits in the central-south segment of the Da Hinggan Ling Range

In recent years big strides have been made in the exploration of ores in the central-south segment of the Da Hinggan Ling Range,though some debates still exist on the metallogenesis and sources of ore-forming materials.Pyrite and other sulfides in direct relation to the Pb-Zn-Ag ore deposits were chosen for the He and Ar isotopic analysis of ore-forming fluids,and the first He and Ar isotope data have been obtained from the study region.3He/4He ratios in 14 samples collected from 7 mining districts are 2.17×10-6-12.52×10-6,averaging 6.86×10-6 and their R/Ra ratios are 1.56-9.01 Ra,averaging 4.37 Ra.By projecting the data points onto the 3He-4He concentrations diagram,all the points fall near the mantle helium area.The calculated mantle-source helium ratios are within the range of 19.58%-76.96%,with an average of 49.52%.Argon isotopic characteristics are close to those of mantle source,indicating that the ore-forming material was transport upwards via the multi-stage evolution of mantle plume and concentrated as ores in the favorable loci of mantle branch structures.

Heat Budget of the South-Central Equatorial Pacific in CMIP3 Models

ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project （AMIP） results, we investigated annual and seasonal variation biases in the upper 50 m of the south-central equatorial Pacific, with a focus on the double-ITCZ bias, and examined the causes for the amplitude biases by using heat budget analysis. The results showed that, in the research region, most of the models simulate SSTs that are higher than or similar to observed. The simulated seasonal phase is close to that observed, but the amplitudes of more than half of the model results are larger than or equal to observations. Heat budget analysis demonstrated that strong shortwave radiation in individual atmospheric models is the main factor that leads to high SST values and that weak southward cold advection is an important mechanism for maintaining a high SST. For seasonal circulation, large surface shortwave radiation amplitudes cause large SST amplitudes.

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Jnurnal of Cenntral South University(CN 43一1516/TB, ISSN 2095-2899) (formerly named Journal of Central South University Technology,CN 43-1231/TD, ISSN 1005-9784) is a comprehensive academic English journal,