Geochemical characteristics and geological significance of chert nodules in Qixia formation,Pingding Mountain,lower Yangtze Plate

The Permian is an important period for the deposition of siliceous rocks on a global scale,but the genesis of chert is still controversial.To better understand the mechanism of chert nodules deposition from Qixia Formation(P1q)(Lower Yangtze Plate,China),we analyzed the major,trace and rare earth elements of these chert nodule samples(CN)and surrounding rock samples(SR)using Inductively Coupled Plasma Mass Spectrometry(ICPMS)and X-ray fluorescence(XRF)technique.The redox state,siliceous sources and depositional environment analysis show that CN have higher contents of SiO2,Fe2O3 and MnO comparing with SR,and their geochemical properties are different.Trace and rare earth elements characteristics reveal that nodules were deposited under the action of biochemistry in the basin,no terrigenous materials contamination was observed and the contribution of upwelling was emphasized.The Al/(Al+Fe+Mn),Fe/Ti and Al-Fe-Mn discrimination diagram indicated the chert nodules are influenced by hydrothermal action.Evidence from redox-sensitive elements such as Th,U,V and Sc suggests that nodules were deposited in a reducing environment.In the convective mixing of hydrothermal action and normal seawater,excessive dissolved silicon and nutrients are absorbed and precipitated by biological action,and then transported by upwelling to shallow water for deposition.All the evidence comes from the trace elements enrichment characters,Rare earth elements and Y(REY)distribution patterns and La/La^*,Ce/Ce^*,Eu/Eu^*,LREE/HREE,Y/Ho and∑REE characteristics.     

EMPIRICAL ORTHOGONAL MODES IN THE WESTERN PACIFIC

The method of empirical orthogonal modes has been widely used since the 1970's in physical oceanography to study and rebuild vertical structures of ocean dynamic factors. Because of the dominance of the low modes, the dynamic profile data can be largely reduced.Up to now, all expressions of empirical orthogonal modes are numerical. In this study, an analytic expression for empirical orthogonal ocean modes is constructed for convenient use whereby any numerical expressions can be repeated.The features of the normal modes decomposed from the buoyance frequency profiles obtained in October of 1986,1987 and 1988 by the R/V Science 1 in the western Pacific are quantitatively examined in this study.     

A STUDY ON EQUILIBRIUM COASTAL PROFILES OF THE CLOSE TIDAL FLAT—A Case Study of Fengxian Tidal Flat

The article analyses the temporal-spatial changes of profiles by EOF(Emipirical Orthogonal Function)analysis and DTM analysis of GIS.These profiles,which are not affected by engineering,are chosen from the coast with successive field monitoring data from 1990 to 1999.Temporal and spatial EOF indicates the obvious stability of coast profile paramclino with steep slopes flat.In spatial scale,high tidal flats and deep-water terraces are in a balance state while upper clino with steep slopes are sensitive and the stability is easy to be destroyes.In temporal scale,the erosion and deposition in this area are kepy in balance in a whole.There are almost no change below -8-9.5m.At the same time,it is the lower limit of tidal affection and the erosion and deposition process from it to high tidal flat keep in balance for many years.So the closre depth is appointed to from -8m to -9.5m(Wusong datum mark).     

Study on dynamic numerical simulation of mountain system in tibet plateau

Tibet Plateau in mountain system is becoming one of the focuses of global technique research, because its crust is marvelous thick, which is twice of the normal thickness of mountain system in lithosphere, and its rapid raise from the Quaternary.By using a finite element analysis software ABAQUS,the numeric analysis has been carried out and presented in this paper for the lithosphere stress field.It is the first time to use the displacement loading in the simulation of Tibet Plateau. During the analysis,the deformed elements are used to simulate the structure band, and friction mechanism is used to model the fracture band. The boundary conditions are given according to the boundary displacements around the Plateau. The stress and displacement distributions are obtained for the geological evolution of the plateau, which are consistent with P axial orientations of the seismic origin mechanism and the measures principle stress orientations. The analysis is also given for the dynamic lithosphere evolution of the Mountain System in the Tibet Plateau.     

ZONALITY OF DISTRIBUTION OF PHYSICO-GEOGRAPHICAL ZONES IN CHINA

With the methods of regression analysis and trend surface analysis, taking the bottom and top lines of dark conifer forest, bottom line of permafrost and the snowline of the latest glaciation in China as examples, this paper discusses the zonality regulaties of the distribution of physico-geographical zones in China. (1) Latitude zonality obeys the mathematical model of normal frequency distribution, being approximate to descending straightly within the latitude of China. (2) Longitude zonality shows that the elevation of physico-geographical zone rises straightly with the distance to east coast. (3) The combination of latitude and longitude zonalities appears a plane inclining from SSW to NNE. The decline of physico-geographical zone resembles a semiellipse- sphere inclining from the Qinghai-Xizang (Tibet) Plateau to northeast China, reflecting the effect of relief. (5) Physico-geographical zonation depends on the combination of hydrothermal conditions. Thus the factors influencing the distribution reg     

Engineering geological characteristics of slide zone soil and stability for one landslide in Tibet

On the basis of geological investigating work and experimental studies on slide zone soil of one landslide in Tibet,the authors analyzed granulometric composition,clay mineral composition and physical and mechanical properties for the soil in the slide zone.The soil samples are gravel containing fine particle.Particles larger than 2 mm occupy the main proportion with the content 51.5%--68.5%.The relative content of clay minerals is low.The clay minerals are illite smectite mixed layer and kaolinite,and their relative contents are 6%--13% and 4%-11%,respectively.The main mineral ingredient is quartz and the relative content is over 30%.Therefore,the soil’s hydrophily is poor.The cohesion and internal friction angle are high,causing preferable physical-mechanical features of slide zone soil.On the basis of the obtained data,the landslide stability is evaluated by means of limit equilibrium method.The safety factors are 3.191 and 1.92 respectively under both natural and normal water level conditions.The study results show that the landslide is stable.It can provide the appropriate basis and reference for landslide stability evaluation and landslide control in Tibet.     

THE TECTONICS BENEATH THE OKINAWA TROUGH

The nature of the crust of the Okinawa Trough is different from that of the continental shelf in the East China Sea. The crust beneath the Trough is in transformation from continental to oceanic and the depth of MOHO in the northern section of the Trough is deeper than in the southern section. Thick sedimentary strata of Neogene and Pleistocene ages are deposited in the Okinawa Trough, and divided into three layers: the upper horizontal layer, the middle layer lightly folded and the lower deformed layer. They were formed in Pleistocene, Pliocene, and Miocene to Paleogene, respectively. The tectonic movement in the southern section is stronger than that in the northern section. Somevolcanic seamounts appear on the bottom of the Trough. On both slopes of the Trough are developed many normal faults and the intrusive igneous rocks. The Okinawa Trough, the back-arc basin,, is an embryonic marginal basin in rifting and spreading. The formation of the Okinawa Trough started in the early Pliocene. The transform     

Origin distribution patterns and floating population modeling: Yiwu City as a destination

Existing quantitative migration studies are mainly at the inter-region or inter-province level for lacking of detailed geo-referenced migration data.Meanwhile,few of them integrate explorative spatial data analysis and spatial regression model into migration analysis.Based on aggregated registered floating population data from 2005 to 2008,the phenomena that population floating to Yiwu City in Zhejiang Province is analyzed at the provincial and county levels.The spatial layout of Yiwu’s pull forces is proved as a V-shaped pattern excluding Sichuan Province based on map visualization method.Using the migration ratio in 2007 as an explanatory variable,two models are compared using ordinary least square,spatial error model and spatial lag model methods for county-level data in Jiangxi and Anhui provinces.The model with migration stock provides an improved fitting over the model without migration stock according to the model fitting results.The floating population flocking into Yiwu City from Jiangxi is determined mostly by migration stock while the determinant factors are migration stock and distance to Yiwu City for Anhui.The distance-decay effect is true for migration flow from Anhui to Yiwu City while the distance rule is not confirmed in Jiangxi with the best fitting model.The correlation between per capita net income of rural labor forces and migration ratio is not significant in Jiangxi and significant but at the 0.1 level only in Anhui.Further analysis shows that the distance,income and man-land ratio are important factors to explain population floating at earlier stage.However,as the dynamic population floating process evolves,the determinant factor would be migration stock.     

A STUDY ON THE ECOLOGICAL CLIMATES OF SOME FAMOUS TEA GROWING AREAS IN HIGH MOUNTAINOUS REGIONS OF CHINA

The tea tree [Camellia sinensis (L) Kuntze] is one of the world's economic crops. It is an especially important crop for southern China. Environmental factors related to the tea yield and quality in some high mountain areas of China are identified in this paper. These factors are: geology, topography, climate, hydrology, soil and vegetation. Climatological factors are the most important. Using data collected from meteorological stations which are situated at the summit and the base of high mountains, this paper discusses ecological climatic problems in growing tea in China. The ecological climatic characteristics of the famous tea areas mainly included are as follows: more . amounts of clouds and fog, less percentage of sunshine, abundant rainfall and high relative humidity in the air, temperatures that rise and fall slowly, daily and annual temperature ranges that are smaller, more days that are suitable for tea growing and low wind speeds in the lee-sides and valleys of mountains. All of these factors     

Abundance and Distribution of Fatty Acids in Sediments of the South Mid-Atlantic Ridge

Sediment samples obtained from the South Mid-Atlantic Ridge were studies by gas chromatography-mass spectrometer(GC-MS) for the abundance and distributions of total fatty acids(TFAs). Approximately 34 fatty acids were identified, with the chain-lengths ranging from C12 to C30. The total concentrations of TFAs(∑TFA) ranged from 7.15 to 30.09 μg g-1 dry sediment, and ∑TFA was weakly correlated with bitumen content(R2 = 0.69). The ∑TFA of samples around hydrothermal areas were significantly higher than that of samples away from hydrothermal areas, indicating intense primary production and large biomass in the hydrothermal areas, and suggesting a close relationship between hydrothermal activity and ∑TFA of samples. The characteristics of the TFA composition in the present study are rich in monounsaturated fatty acids and lacking in polyunsaturated fatty acids, and the ratios between the concentrations of monounsaturated fatty acids and ΣTFAs in samples close to the hydrothermal areas, are about 0.8, but for samples far from the hydrothermal areas, they are only about 0.5. Several fatty acids(e.g., a/i C15:0 and C16:1ω7), which are signature biomarkers for sulfur-metabolizing bacteria, show the same distribution trend as ∑TFA of samples, further highlighting the close relationship between fatty acid content and hydrothermal activity and/or hydrothermal communities. The metabolic activities of hydrothermal communities, especially those of microorganisms, are likely the main source of fatty acids in samples.     

Multivariant statistical analysis for diagenetic information of chert from southern Tibet,China

There are large scale chert formations of different ages exposed widely in southern Tibet,along Yarlung-Zangbo suture zone. The typical chert specimens were sampled from Pengcuolin,Xialu and Zongzhuo profiles. Multivariate statistical analysis is applied for effectively extracting the geochemical information of the chert,and the raw data are processed by R-factor analysis. The first,second and third factors representing terrigenous,authigenic and hydrothermal constituents are extracted from the analysis res...     

Geochemistry and metallogenic age of Sishanlinchang gold-silver deposit in Jidong of Heilongjiang

the Sishanlinchang gold-silver deposit is mainly composed of gold-quartz vein type ores.It has many kinds of sulfides and gold in high grade.The Au has a close correlation with As,Pb,Ag and Cu.Geochemically,the deposit is characterized by relatively enrichment in LREE with moderate or lower Eu negative anomaly.Sulfur isotopes appear as single and deep source,and lead isotopes indicate the Pb is from the earth’s mantle and crust,which mainly are orogenic belt Pb,the ore-forming fluid has a temperature of 215℃-350℃ and a low salinity with a mixture of characteristics of magmaitc hydrothermal and meteoric water.The ore-forming age is 111.1-111.4 Ma.The deposit is formed in mineralization and precipitation of metallogenic materials caused by the mixture of the magmatic hydrothermal fluid and meteoric water.     

2015年西藏定日MW5.7地震震源参数估计和静态应力触发研究

采用InSAR形变监测资料计算2015年西藏定日M_W5.7地震同震形变场,反演发震断层几何参数和滑动分布。在此基础上,研究尼泊尔M_W7.8主震对定日地震的静态库仑应力触发影响。综合分析地震滑动机制和构造特征,认为定日断层为西倾隐伏断层。反演结果表明,地震破裂相对集中,主要深度在6~9 km,破裂以正断滑动为主。发震断层走向约178°,倾角约 48°,破裂区长约5 km,宽约5 km,最大滑动量约0.2 m,释放的地震矩约3.7×10¹⁷ N·m,对应矩震级M_W5.6。尼泊尔主震同震库仑应力在定日地震震源处约为0.2 bar,造成藏南申扎-定结拉张地堑应变加载。     

山东中南部地区含金刚石燧石砾岩的地貌特征和形成时代

本文对山东中南部含金刚石燧石砾岩地区的地貌、新构造、早第三纪地层进行了研究和划分,在该区首次发现了河流袭夺现象。本区含金刚石燧石砾岩主要赋存在古岩溶地貌中,其孢粉组合是以杉科粉占优势(特别是破隙杉粉),栎粉、榆粉也有较高含量,以热带、亚热带植物花粉为主的基本特征,含金刚石燧石砾岩的形成时代为早第三纪渐新世。     

西藏亚东-谷露裂谷带运动特征的InSAR研究

亚东-谷露裂谷等南北向分布的大型地堑在青藏高原新生代构造演化中发挥着重要作用,该研究对理解青藏高原中南部地堑在第四纪构造演化的地位具有重要意义。基于欧空局Envisat卫星2003~2008年SAR数据,利用SBAS时序InSAR技术,去除地形、大气、轨道等因素的影响,获取亚东-谷露裂谷带及邻区的LOS速度场,并反演亚东-谷露裂谷带的滑动速率和闭锁深度。结果表明,亚东-谷露裂谷带南段与北段具有相同的倾滑速率,均为1 mm/a;其闭锁深度南段为31 km,北段为22 km;其断层倾角南段为52°,北段为40°,与地质结果一致。     

河南夏馆-二郎坪一带叠加改造型金矿床地质特征及成矿模式

河南内乡夏馆-西峡二郎坪一带金矿床(点)广泛分布,成矿类型多样,产出条件复杂,岩体与围岩接触带以及中元古代和早古生代地层中都有金矿形成.根据成矿物质、成矿流体来源和成矿机制,将产于接触带和地层中的金矿体分为5种类型,它们是在火山、火山沉积和正常沉积等不同背景下,由岩浆热液、变质热液或地下水热液叠加改造(再造)形成的,每类矿床都经历了多期多阶段成矿过程,以后期热液交代、充填成矿为主.构造对金矿形成有明显控制作用,区域性深大断裂控制金成矿带,二级韧脆性剪切带控制金矿床分布,三级层间破碎带、断裂裂隙带和接触带构造控制矿体就位.构造热液的叠加改造或再造主导了成矿作用.     

A study on accumulation and distribution of gas in southern Songliao Basin

A number of isolated fault sags in Late Jurassic--Early Cretaceous were developed in the early stage of southern Songliao Basin,and unified to a depression basin in the late stage.Therefore,multiple isolated lower petroliferous systems were formed with fault sags as source rocks.The source rocks of fault sags in Late Jurassic--Early Cretaceous were mainly described with gas generation as favorable source rocks,leading to the southern Songliao Basin rich in natural gas resources combined with organic gas resources in Nenjiang Formation.A number of tectonic movements in southern Songliao Basin led to the formation of abundant structural traps and complex fault systems,and controlled the distribution strata and positions of sources rocks in Late Jurassic--Early Cretaceous fault sags.The oil-gas reservoirs can be divided into two types,i.e.,primary and secondary ones.The primary oil-gas reservoirs were distributed in the fault sag strata and the bottom of overlying depression strata(lower Quan-1 Member).The oil-gas reservoir accumulation depended on the trap development situation and the distance from source rocks.The preservation conditions of oil-gas reservoirs depended on the degree of reconstruction in the late tectonism.The secondary oil-gas reservoirs were distribution in the Quantou Formation of depression strata,where oil and gas reservoir accumulation depended on three conditions,i.e.,trap development situation,deep gas sources and the fault to connect the shallow traps and deep gas sources.The southern Songliao Basin is rich in lower coal type gas,upper oil-gas and biogas resources,which are important resources in the future.     

Petrogenesis of Early Cretaceous riebeckite granophyres in southern Da Hinggan Mts.

This paper reports lithologic features,K--Ar age and geochemical data of riebeckite granophyres from Aliwula area in the southern Da Hinggan Mts.,aiming to reveal the petrogenesis of riebeckite granophyres.K-Ar age of riebeckite granophyres is 126 ± 2 Ma,implying that the riebeckite granophyres formed in the Early Cretaceous.The granophyres are rich in riebeckites and with a lot of melt-fluid inclusion in its quartz phenocrysts.The granophyres are characterized by extensive enrichment in SiO2,FeO,and(Na2O+K2O) and depletion in MgO and CaO,strong negative Eu anomalies and strong positive Ce anomalies.Additionally,the riebeckite granophyres not only have high total REE contents and display enrichment of HFSEs(for example Zr,Hf,Nb,Ta),but also are strong in depletion of LILEs(e.g.Ba,Sr) as well as high Ga /Al ratios.Primitive mantle-normalized REE pattern significantly displays REE M--W tetrad effect.REEs fractionate evidently and highly enrich in LREE,but are uneven distribution in the rocks.Taken together,we conclude that the riebeckite granophyres are similar to typical A-type granite,which could be derived from stretching environments in the Early Cretaceous.The granophyres originated from residual melt which underwent highly differentiation process,and were formed in magmatic-hydrothemal transition stage at last.     

Metallogenic origin of Sipingshan hot spring gold deposit in Hulin of Heilongjiang and its metallogenic mode

Sipingshan gold deposit is gold-bearing sillcalite in type. There only exist a few kinds of sulfide in the ore and it is lower in content. The gold degree is lower. Au is closely related to the Ag,Cu,Pb,As and Hg elements. The upper sillcalite has Eu and Ce negative anomaly,and the lower sillcalite has Eu positive anomaly. however,the hot spring cemented breccia and rhyolite porphyry have Eu negative anomaly;the S isotope component has deep-seated magmatic sulfur and terrestrial sulfate characteristic;and the Pb isotope has the character of the mixture origin of crust and mantle that is mainly dominated by Pb in the orogenic belt. The ore-forming fluid temperature is 180℃-244℃,characterized by magmatic hydrothermal and meteoric water;and the ore-forming age is 87 Ma. The deposit was formed by the metallogenic fluid in the tectonic fault zone overflowing near the earth’s surface and leading to the metallogenic function and the metallogenic substance deposition.