Os isotopic composition of the earth’s primitive upper mantle

The osmium isotopic ratio of¹⁸⁷Os/¹⁸⁸Os ranging from 0.126 to 0.127 for the primitive upper mantle (PUM) is obtained according to the correlation between¹⁸⁷Os/¹⁸⁸Os and Al₂O₃ of mantle-derived xenoliths and orogenic peridotites, which consists with Allegre and Luck’s ALM value and similar to Yin’s nuggets uniform reservoir (NUR) value. It shows that the Os isotope ratio is lower than enstatite or ondinary chondrites, similar to carbonaceous chondrites (CV3).     

Earth’s oldest records of sea-floor spreading

Geologists have long-debated about when plate tectonics started on the planet. One of the key indicators has been whether or not fragments of oceanic crust, generated at sea-floor spreading centers, are preserved in the planet’s oldest crust. New research integrating what has been learned about the variations in modern sea floor spreading environments with the geological record of the oldest preserved crust on Earth     

Improving the accuracy of GRACE Earth’s gravitational field using the combination of different inclinations

In this paper, the GRACE Earth’s gravitational field complete up to degree and order 120 is recovered based on the combination of different inclinations using the energy conservation principle. The results show that because different inclinations of satellite are sensitive to the geopotential coefficients with different degrees l and orders m, the design of GRACE exploiting 89o inclination can improve effectively the accuracy of geopotential zonal harmonic coefficients. However, it is less sensitive to the geopotential tesseral harmonic coefficients. Accordingly, the second group of GRACE exploiting lower inclination is required to determine high-accurately the geopotential tesseral harmonic coefficients and cover the shortage of the single group of GRACE exploiting 89o inclination. Two groups of GRACE individually exploiting 89o+(82o－84o) inclinations are the optimal combination of the Earth’s gravitational field recovery complete up to degree and order 120. In the degree 120, the joint accuracy of cumulative geoid height based on two groups of GRACE individually exploiting 89o and 83o inclinations is averagely 2 times higher than the accuracy of a group of GRACE exploiting 89o inclination.     

Improving the accuracy of GRACE Earth’s gravitational field using the combination of different inclinations

In this paper, the GRACE Earth’s gravitational field complete up to degree and order 120 is recovered based on the combination of different inclinations using the energy conservation principle. The results show that because different inclinations of satellite are sensitive to the geopotential coefficients with different degrees l and orders m, the design of GRACE exploiting 89o inclination can improve effectively the accuracy of geopotential zonal harmonic coefficients. However, it is less sensitive to the geopotential tesseral harmonic coefficients. Accordingly, the second group of GRACE exploiting lower inclination is required to determine high-accurately the geopotential tesseral harmonic coefficients and cover the shortage of the single group of GRACE exploiting 89o inclination. Two groups of GRACE individually exploiting 89o+(82o－84o) inclinations are the optimal combination of the Earth’s gravitational field recovery complete up to degree and order 120. In the degree 120, the joint accuracy of cumulative geoid height based on two groups of GRACE individually exploiting 89o and 83o inclinations is averagely 2 times higher than the accuracy of a group of GRACE exploiting 89o inclination.     

Isotopic composition of atmospheric water vapor before and after the monsoon’s end in the Nagqu River Basin

Stable isotopes of water are widely used in scientific research to reconstruct paleoclimate and paleoenviron- ment variations[1―4]. Atmospheric water vapor plays a keyrole in the precipitation events. Therefore, the isotopic composition of atmospheric water vapor has a direct effect upon that of precipitation[5,6]. Observation of stable isotope variation of atmospheric water vapor has an important significance to indicate the moisture origins andmoisture transport in the study area. Based on …     

Isotopic composition of atmospheric water vapor before and after the monsoon’s end in the Nagqu River Basin

Atmospheric water vapor samples were collected in the Nagqu River Basin in the middle of Tibetan Plateau between August and October in 2004. Results show that there exist some fluctuations of the δ^18O of atmospheric water vapor, especially before and after the monsoon＇s end.Moreover, the variety trend of the δ^18O of atmospheric water vapor inverse correlates with that of dew point. Precipitation events make an important effect upon the variation of δ^18O of atmospheric water vapor. During the whole sampling period, the δ^18O values of atmospheric water vapor are low while precipitation events occurred. The moisture origins w also contribute to the variation of δ^18O of atmospheric water vapor. The oceanic moisture transported by the southwest monsoon results in lower δ^18O of atmospheric water vapor in the Nagqu River Basin. Compared with the influence of the oceanic moisture, the δ^18O values, however, appear high resuiting from the effect of the continental air mass in this region.     

Spin transition of iron in magnesiowüstite in the Earth's lower mantle

Iron is the most abundant transition-metal element in the mantle and therefore plays an important role in the geochemistry and geodynamics of the Earth's interior. Pressure-induced electronic spin transitions of iron occur in magnesiowüstite, silicate perovskite and post-perovskite. Here we have studied the spin states of iron in magnesiowüstite and the isolated effects of the electronic transitions on the elasticity of magnesiowüstite with in situ X-ray emission spectroscopy and X-ray diffraction to pressures of the lowermost mantle. An observed high-spin to low-spin transition of iron in magnesiowüstite results in an abnormal compressional behaviour between the high-spin and the low-spin states. The high-pressure, low-spin state exhibits a much higher bulk modulus and bulk sound velocity than the low-pressure, high-spin state; the bulk modulus jumps by approximately 35 percent and bulk sound velocity increases by approximately 15 percent across the transition in (Mg0.83,Fe0.17)O. Although no significant density change is observed across the electronic transition, the jump in the sound velocities and the bulk modulus across the transition provides an additional explanation for the seismic wave heterogeneity in the lowermost mantle. The transition also affects current interpretations of the geophysical and geochemical models using extrapolated or calculated thermal equation-of-state data without considering the effects of the electronic transition.     

Real-time rapid prediction of variations of Earth’s rotational rate

Real-time rapid prediction of variations of the Earth＇s rotational rate is of great scientific and practical importance. However, due to the complicated time-variable characteristics of variations of the Earth＇s rotational rate （i.e., length of day, LOD）, it is usually difficult to obtain satisfactory predictions by con- ventional linear time series analysis methods. This study employs the nonlinear artificial neural net-works （ANN） to predict the LOD variations. The topology of the ANN model is determined by minimizing the root mean square errors （RMSE） of the predictions. Considering the close relationships between the LOD variations and the atmospheric circulation movement, the operational prediction series of axial atmospheric angular momentum （AAM） is incorporated into the ANN model as an additional input in the real-time rapid prediction of LOD variations with 1-5 days ahead. The results show that the LOD prediction is significantly improved after introducing the operational prediction series of AAM into the ANN model.     

High-speed flowing plasmas in the Earth’s plasma sheet

A research topic of great interest to the space physics community is the observation of plasmas flowing at hundreds of kilometers per second in the Earth’s plasma sheet. Although considerable effort has been made to understand the source of fast-flowing plasmas, many questions remain unanswered about the mechanisms that produce high-speed flows and the effects they have on magnetospheric disturbances, especially their contributions to magnetospheric convection and substorms. In this paper, we discuss briefly the history of high-speed flows and review the proposed mechanisms, signatures of high-speed flows in auroras and their interaction with the background plasma. We then summarize the relationships between high-speed flows and magnetic structures, discuss questions associated with substorms, and finally pose several important scientific questions that need to be addressed.     

Evidence for tritium production in the Earth’s interior

We have made a new investigation on the vertical profiles of tritium and helium isotopes in Lakes Van and Nemrut （Eastern Turkey）, using experimental data from the reference by Kipfer et al. for study of long-term vertical mixing and deep water renewal in Lake Van. Lakes Van and Nemrut are crater lakes. Lake Nemrut is at the western border of Lake Van. The ^3He and ^4He are injected at the bottom of Lakes Van and Nemrut, and the both helium isotopes are confirmed from the mantle source. From ^3H （tritium） data in Lakes Van and Nemrut, we have observed ＂^3H anomaly＂ at the vertical profile of ^3H concentrations in Lake Nemrut. The ^3H concentration at the lake bottom is 10% higher than at the surface. The difference of ^3H concentrations between surface and bottom is about 3.7±1.2 TU. This excess ^3H should be injected from the lake bottom. An investigation on the origin of the injected tritium has been made. The results show the conventional origins are excluded, such as residence of precipitation tritium from nuclear testing in the early 1950s--1960s and tritium from known nuclear reactions. Based on the correlation of excess ^3H with ^3He and heat flow in Lake Nemrut, we infer that the ^3He and ^3H might be all from the mantle source, and produced by the supposed natural-nuclear-fusion, which might occur in an environment rich in water （H） and （U ＋ Th） at high temperature and high pressure in the deep Earth. Detection of tritium in the Earth＇s interior is a key evidence for exploration of natural nuclear fusion in the deep Earth. Based on the published data, we have found that the excess ^3He and ^3H injected at the bottom of Lake Laacher （Germany） were also released from the mantle source. The present work will be helpful to the further study of mechanism of natural nuclear fusion in the Earth＇s interior.     

Nonlinear dependence of anomalous resistivity on the reconnecting electric field in the Earth’s magnetotail

Based upon the observational data of the fast magnetic reconnection in the nearly collisionless magnetotail and the particle in cell (PIC)simulations on the electron acceleration in the reconnecting current sheet with guide magnetic field,we self consistently solved one dimension Vlasov equation with the magnetotail parameters and realistic mass ratio to explore the relationship between the anomalous resistivity and the induced electric field.As compared with theoretic formula for the current driven ion-acoustic and Buneman anomalous resistivity,the anomalous resistivity may result from the ion acoustic instability for small reconnecting electric field and the Buneman instability for large reconnecting electric field.The discrepancy between the theoretic results and numerical simulations may be caused by the high frequency instability that results from the deviation of electron distribution from Maxwellian one.These results are consistent with the early experimental results and favorable for the fast reconnection to take place.     

Thermodynamic evolution of lithosphere of the North China craton： Records from lower crust and upper mantle xenoliths from Hannuoba

Lithospheric thinning in East China attracts much attention of geologists. In many cases where a lithospheric thinning is inferred, the trigger for instability is a preced-ing episode of crustal thickening by the continental colli-sion[1]. Lithospheric processes (e.g. lithospheric thinning) could be recorded by the thermal history of the lower crustal and upper mantle xenoliths. Xu et al.[2] suggested that the cooling (from >1200 to 850℃) recorded by spinel harzburgite from Northeast China …     

Velocity structure of the crust and uppermost mantle in the boundary area of the Tianshan Mountains and the Tarim Basin

A portable 3-component broadband digital seismic array was deployed across the Tianshan orogenic belt (TOB) to investigate the lithospheric structure. Based on receiver function analysis of the teleseismic P-wave data, a 2-D S-wave velocity profile of the boundary area of the TOB and the Tarim Basin was obtained at the depths of 0--80 km.Our results reveal a vertical and lateral inhomogeneity in the crust and uppermost mantle. Four velocity interfaces divide the crystalline crust into the upper, middle and lower crust. A low velocity zone is widely observed in the upper-middle crust. The depth of Moho varies between 42 and 52 km. At the north end of the profile the Moho dips northward with a vertical offset of 4--6 km, which implies a subduction front of the Tarim Basin into the TOB. The Moho generally appears as a velocity transitional zone except beneath two stations in the northern Tarim Basin, where the Moho is characterized by a typical velocity discontinuity. The fine velocity structure and the deep contact deformation of the crust and upper most mantle delineate the north-south lithospheric shortening and thickening in the boundary area of the TOB and the Tarim Basin, which would be helpful to constructing the geodynamical model of the intracontinental mountain-basin-coupling system.     

The New Detection and the Basic Characteristics of the Structural System of Taiwan Region of China—Using the Earth Satellite’s Remote-sensing Images to Explain the Structural System of Taiwan Region of China

This text uses the regional geological investigation data and the remote sensing image data of earthsatellite remote sensing to synthetically analyze the structural system of Taiwan region of China. Authors detection-marked and assurance-marked and divided 5 kinds of structural system of the Taiwan region： （ 1 ） the wreath-shaped structural system, （2） the N-N-E oriented structural system, （3） the S-N oriented structural system, （4） the N-E oriented structural system, （5） the are-shaped structural system. Combination of the texture faces and associated method were adopted to recover and reconstruct the structural evolution sequences and the formation periods. In this paper, problems such as the development process in geology etc. are also discussed, contributing new information to research the structural field of the East Asia and its tectonic plate movements and structural actions inside the land plate .     

Introduction about Eileen Chang’s translation of the Old Men and the Sea

People in our country know Eileen Chang mainly as an outstanding writer and literator.In fact she is appreciated more than being a writer internationally.Yet Chang’s outstanding talent as a trans1ator is known very 1ittle in mainland China.This thesis selects Eileen Chang’s translation phenomenon as the object of study. Mainly because at first, the translator is of course the decisive factor that makes the target text equivalent to the source text,and case study of outstanding translators obviously is a very important part of both translation theories and practice. Among the factors influencing translation, the subjectivity of the translator is the key one. For a translator who is also a writer,his/ her writing view influences his/ her translating ractice. Eileen Chang’s writing view is inflected in her translation of The Old Man and the Sea by Ernest Hemingway. In my thesis, I would analysis her skill when translating the Old Man and the Sea. I found that she reflected her own attitude to the life when translating the novel.     

Experimental study on the P wave velocity in rocks from lower crust and crust-mantle transitional zone beneath the Hannuoba

Cenozoic basalt-borne mafic granulite-facies plagioclase pyroxenite and eclogite-facies garnet pyroxenite xenoliths from the Hannuoba, as well as nearby Archean terrain granulites, are selected for the experimental study on the P wave velocity at high temperature and high pressure in order to reveal the present-day compositional features for the lower crust and crust-mantle transitional zone. Results show that mafic xenoliths have high Vp (7.0～8.0 km/s), in contrast, the Archean terrain granulites have low Vp (<7.0 km/s). High Vp mafic xenoliths can represent the present-day compositional features for the lower crust and crust-mantle transitional zone beneath the Hannuoba. This provides new evidence for the crust vertical growth and the formation of the crust-mantle transitional zone resulting from the magma underplating. Low Vp Archean granulite still remains the characteristics of the early lower crust.     

Dramatic variations in the Earth’s main magnetic field during the 20th century

Analysis of the International Geomagnetic Reference Field (IGRF) 1900-2000 shows that the Earth's main magnetic field has changed dramatically during the 20th century: its dipole moment has decreased by 6.5% since 1900, the strengths of its quadrupole and octupole have increased by 95% and 74%, respectively, four major planetary-scale magnetic anomalies on the Earth's surface have enhanced by 21%-56%, and the magnetic center has shifted 200 km towards the Pacific Ocean. These time-variation features are similar to the behavior before a geomagnetic polarity reversal.     

Elemental composition in the sediments of the Yangtze and the Yellow Rivers and their tracing implication

Elemental compositions in the surface sediments of the Yangtze River and the Yellow River are quite different. The Yangtze River' s sediment is rich in K, Fe, Mg, Al and most of trace elements, and its elemental composition show remarkable spatial variations, whereas the Yellow River s sediment has higher contents of Ca, Na, Sr, Ba, Zr and Hf, and the elemental composition remains relatively stable. The ratios of some elements are also different in the sediments of the two rivers. The elemental composition of the Yangtze River sediment results from widely distributed igneous rocks and complicated source rocks and strong chemical weathering in the Yangtze River catchment basin, while the main provenance of the Yellow River sediment is the Loess Plateau which has dominant influence on the elemental composition, and the intense physical weathering is another controlling factor. The elements such as Cu, Zn, Sc, Ti, Fe, V, Ni, Cr, Co, Li and element ratios such as La/Sc, La/Co, Th/Co, Ti/Zr and Zr/Y can be used as the tracers to distinguish the Yangtze River sediment from the Yellow River s. The tracers can be used in the study of the mixing and distribution of the substances of the two rivers matters in coastal zones of China.     

On the Generalizations of Hilbert’s Inequality

1 IntroductionLetan,bn>0.If 0<∑∞n=1a2n< ∞,0<∑∞n=1b2n< ∞,then∑∞m=1∑∞n=1ambnm n<π∑∞n=1a2n∑∞n=1b2n1/2(1)theinequality(1)is well knownintheliterature as Hilbert’sinequality.The associatedintegral formof(1)maybe writteninthe following:If 0<∫0∞f2(t)dt< ∞,0<∫0∞g2(t)dt< ∞,then∫0∫∞0∞f(xx) g(yy)dxdy<π∫(0∞f2(t)d∫t0∞g2(t)dt)1/2,(2)where the constantπare best possible in(1)and(2).In recent years,some i mprovements and extensions ofHilbert’s inequality have been given.Fori…     

Possible seismic reflector in the lower crust： Evidence from fabrics and experiments of seismic velocity on layered gabbro at high temperature and high pressure

Lattice preferred orientations (LPO) of plagioclase and augite are measured on layered gabbro from the Panxi region, Sichuan Province. The LPO concentration [010] of plagioclase and [100] of augite are perpendicular to the foliation, which indicates a kind of growth fabric associated with crystallizing habits of minerals when the magma is solidifying under the compaction. Calculated seismic velocities based on LPO data of minerals give rise to rather strong anisotropy 5.81% and 5.54% for compressional seismic wave (Vp) and shear seismic wave (Vs), respectively. The experiments at high temperature and high pressure show that the P-wave velocity of layered gabbro is 6.4-6.97 km/s with the maximum Vp anisotropy 5.22% and the Poisson‘s ratio is between 0.28-0.31. According to the comparison of fabrics with seismic velocities of layered gabbro, it is suggested that the large-scale layered intrusive body or the similar layered geological body may exist in the lower crust of this area. Such a layered intrusive body which has strong seismic anisotropy may be the seismic reflector in the lower crust.