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121.
InformationsPublication Available
Proceedings of the 2nd Hotine Marussi Symposium on Mathematical Geodesy edited by F. Sacerdote—F. Sansò 相似文献122.
那拉提山北缘寒武纪玄武岩的元素地球化学特征及构造意义 总被引:3,自引:2,他引:3
我国西南天山地区那拉提北缘断裂北侧出露寒武纪(516.3±7.4Ma)橄榄拉斑玄武岩,其Al2O3(120.71%-14.14%)、P2O5(0.09%-0.21%)含量较低,TiO2(1.39%-2.35%)、MgO(5.35%-8.14%)含量中等,全Fe2O3(11.74%-16.03%)含量较高,球粒陨石标准化稀土分布型式平坦,(La/Sm).和(Y/Nb).比值接近1,为过渡型洋脊玄武岩(T-MORB);并且Th/Ta比值(0.8—1.5)低,高场强元素(Nb,Ta,Zr,Hf,P)没有明显亏损,缺乏陆壳混染或俯冲带流体活动的印迹.部分T-MORB的Fe、Ti含量较高(FeO^T〉12%,TiO2〉2%,FeO^T/MgO〉1.75),Mg^#值(0.40—0.49)和Cr(53×10^-6-110×10^-6)含量较低,属于Fe-Ti玄武岩(ferrobasalt),应为岩浆依Fenner趋势发生较高程度结晶分离演化的产物,很可能形成于洋中脊的扩展型裂谷环境.我们认为,那拉提北缘寒武纪T-MORB和Fe-n玄武岩可能与境外吉尔吉斯斯坦境内北天山南缘的旱古生代Terskey蛇绿岩带相连,为Terskey蛇绿岩的残片;寒武纪我国境内发育Terskey洋.那拉提北缘断裂可能与尼古拉耶夫线相连,代表西南天山地区Terskey洋闭合形成的一条早古生代缝合带. 相似文献
123.
Reiner Rummel 《Journal of Geodesy》1976,50(2):181-192
The well known least squares collocation model (I) $$\ell = Ax + \left[ {\begin{array}{*{20}c} O \\ I \\ \end{array} } \right]^T \left[ {\begin{array}{*{20}c} s \\ {s' + n} \\ \end{array} } \right]$$ is compared with the model (II) $$\ell = Ax + \left[ {\begin{array}{*{20}c} R \\ I \\ \end{array} } \right]^T \left[ {\begin{array}{*{20}c} s \\ n \\ \end{array} } \right]$$ The basic differences of these two models in the framework of physical geodesy are pointed out by analyzing the validity of the equation $$s' = Rs$$ that transforms one model into the other, for different cases. For clarification purposes least squares filtering, prediction and collocation are discussed separately. In filtering problems the coefficient matrix R becomes the unit matrix and by this the two models become identical. For prediction and collocation problems the relation s′=Rs is only fulfilled in the global limit where s becomes either a continuous function on the earth or an intinite set of spherical harmonic coefficients. Applying Model (II), we see that for any finite dimension of s the operator equations of physical geodesy are approximated by a finite matrix relation whereas in Model (I) the operator equations are applied in their correct form on a continuous, approximate function \(\tilde s\) . 相似文献
124.
Reiner Schlitzer 《Journal of Oceanography》2004,60(1):53-62
A global ocean inverse model that includes the 3D ocean circulation as well as the production, sinking and remineralization
of biogenic particulate matter is used to estimate the carbon export flux in the Pacific, north of 10°S. The model exploits
the existing large datasets for hydrographic parameters, dissolved oxygen, nutrients and carbon, and determines optimal export
production rates by fitting the model to the observed water column distributions by means of the “adjoint method”. In the model, the observations can be explained satisfactorily with an integrated carbon export production of about 3 Gt
C yr−1 (equivalent to 3⋅1015 gC yr−1) for the considered zone of the Pacific Ocean. This amounts to about a third of the global ocean carbon export of 9.6 Gt
C yr−1 in the model. The highest export fluxes occur in the coastal upwelling region off northwestern America and in the tropical
eastern Pacific. Due to the large surface area, the open-ocean, oligotrophic region in the central North Pacific also contributes
significantly to the total North Pacific export flux (0.45 Gt C yr−1), despite the rather small average flux densities in this region (13 gC m−2yr−1). Model e-ratios (calculated here as ratios of model export production to primary production, as inferred from satellite observations) range
from as high a value as 0.4 in the tropical Pacific to 0.17 in the oligotrophic central north Pacific. Model e-ratios in the northeastern Pacific upwelling regions amount to about 0.3 and are lower than previous estimates.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
125.
Wen Su Ming Zhang Simon A. T. Redfern Jun Gao Reiner Klemd 《International Journal of Earth Sciences》2009,98(6):1299-1309
Chemically-zoned amphibole porphyroblast grains in an eclogite (sample ws24-7) from the western Tianshan (NW-China) have been
analyzed by electron microprobe (EMP), micro Fourier-transform infrared (micro-FTIR) and micro-Raman spectroscopy in the OH-stretching
region. The EMP data reveal zoned amphibole compositions clustering around two predominant compositions: a glaucophane end-member
(
B
Na2
C
M2+
3 M3+
2
T
Si8(OH)2) in the cores, whereas the mantle to rim of the samples has an intermediate amphibole composition (
A
0.5
B
Ca1.5Na0.5
C
M
2+
4.5 M
0.53+
T
Si7.5Al0.5(OH)2) (A = Na and/or K; M
2+ = Mg and Fe2+; M
3+ = Fe3+ and/or Al) between winchite (and ferro-winchite) and katophorite (and Mg-katophorite). Furthermore, we observed complicated
FTIR and Raman spectra with OH-stretching absorption bands varying systematically from core to rim. The FTIR/Raman spectra
of the core amphibole show three lower-frequency components (at 3,633, 3,649–3,651 and 3,660–3,663 cm−1) which can be attributed to a local O(3)-H dipole surrounded by
M(1) M(3)Mg3,
M(1) M(3)Mg2Fe2+ and
M(1) M(3) Fe2+
3, respectively, an empty A site and
T
Si8 environments. On the other hand, bands at higher frequencies (3,672–3,673, 3,691–3,697 and 3,708 cm−1) are observable in the rims of the amphiboles, and they indicate the presence of an occupied A site. The FTIR and Raman data from the OH-stretching region allow us to calculate the site occupancy of the A, M(1)–M(3), T sites with confidence when combined with EPM data. By contrast M(2)- and M(4) site occupancies are more difficult to evaluate. We use these samples to highlight on the opportunities and limitations
of FTIR OH-stretching spectroscopy applied to natural high pressure amphibole phases. The much more detailed cation site occupancy
of the zoned amphibole from the western Tianshan have been obtained by comparing data from micro-chemical and FTIR and/or
Raman in the OH-stretching data. We find the following characteristic substitutions Si(T-site) (Mg, Fe)[M(1)–M(3)-site] → Al(T-site) Al[M(1)–M(3)-site] (tschermakite), Ca(M4-site)□ (A-site) → Na(M4-site) Na + K(A-site) (richterite), and Ca(M4-site) (Mg, Fe) [M(1)–M(3)-site] → Na(M4-site) Al[M(1)–M(3)-site] (glaucophane) from the configurations observed during metamorphism. 相似文献
126.
The freshwater budget of a tidal flat area is evaluated from long-term hydrographic time series from an observation pole positioned in a tidal channel in the Hörnum Basin (Germany). For each tidal cycle, the freshwater budget is calculated from the total imported and exported water volumes and the corresponding mean densities. The variability of the budget on a tidal scale is characterised by a period of twice the tidal period, exhibiting a minimum when the tidal flats are dry around daylight hours during the foregoing low tide, and a maximum when low tide occurs at night; enhanced evaporation on the flats at daylight hours is identified as the driving process. On the average over one year, while winter observations are missing, the freshwater budget is negative for the years 2002–2005 and positive only for 2006. The interannual mean is negative and amounts to a freshwater loss of about 2 mm day−1, although the large-scale climate in this region is humid. The results demonstrate that the bulk parametrisations for the latent and sensible heat flux between the ocean and the atmosphere must not be applied for the tidelands. 相似文献
127.
Solar particle events with helium-over-hydrogen enhancement in the energy range up to 100 MeV nucl−1
J. Torsti L. Kocharov J. Laivola S. Pohjolainen S.P. Plunkett B.J. Thompson M.L. Kaiser M.J. Reiner 《Solar physics》2002,205(1):123-147
Flux measurements of solar energetic particles (SEPs) in the ERNE instrument onboard SOHO indicate that the abundance of 4He-nuclei compared to protons in the energy range up to 100 MeV nucl–1 was exceptionally high during the particle events on 27 May 1998 and 28 December 1999. The 4He/p ratio stayed between 0.15–0.50 for more than ten hours. There was also a prolonged enhancement in helium-3, 3He/4H 1%. Observations of EIT and LASCO on board SOHO confirm that the originators of both SEP events were western eruptions, flares and coronal mass ejections (CMEs). The onset of the SEP release took place close to the maximum of flares which were probably triggered by the rising CMEs. The observations suggest that the SEP events were started with the flare-(pre)accelerated particles, but impact of the CME-associated shocks might explain the continuation and modification of the helium and proton fluxes well after the flare production. These observations support the idea that the helium enhancements in the CME-associated events reflect the availability of seed particles that originate previously in flares. 相似文献
128.
Reiner Kleinschrodt 《地学学报》1996,8(3):236-244
In Sri Lanka a suite of rocks is regionally exposed which once formed a part of the middle to lower crust of a collisional orogen with about doubled crustal thickness. A subhorizontal to gently west-dipping major thrust zone (Highland Basal Thrust) crosses Sri Lanka from NNE to SSW. It separates a granulite facies upper unit, the Highland Complex from an amphibolite facies lower unit, the Vijayan Complex with a displacement of more than 300 km. The basal Highland Complex was migmatized during thrusting. Rheological contrasts between dry granulites and migmatites were high in the presence of partial melts. Granulite facies fragments within the migmatites vary from the decimetre to kilometre scale. Granulites in the area of Kataragama, formerly interpreted as the Kataragama Klippe, are now identified as a large-scale raft within the migmatites, which is completely separated from the overriding Highland Complex. During thrusting strain was concentrated in the migmatized basal parts of the Highland Complex. After crystallization of the migmatites thrusting continued, and strain was still localized within the migmatites. Therefore, granulite facies parageneses, structures and textures are preserved in the granulite rafts. The deviation of the granulite facies structures in the Kataragama raft from the general trend in the Highland Complex is interpreted to indicate counterclockwise rotation of the whole raft by about 90° around a subvertical rotation axis. 相似文献
129.
位于中国南天山的西天山高压变质带代表了伊犁-中天山与塔里木两个板块间古生代南天山洋的古俯冲混杂岩带.高压变质带内广泛发育高压脉.为探讨古俯冲深部流体来源及运移特点及板块俯冲特征,对高压脉和主岩的全岩及主要的高压变质矿物的氧同位素进行了分析.高压脉的δ18O值变化于+8.28‰与+10.70‰之间,多数在+9.50‰±1范围内.基性变质岩的主岩与高压脉具相似的氧同位素组成,变化于+9.25‰~+10.10‰之间.高压脉和主岩的全岩δ18O值变化不大.高压脉与相邻主岩间、同一高压脉中间与边部间氧同位素组成的变化没有明显的规律,一般变化不大,对于大多数脉-主岩对,变化小于1‰.与全岩完全不同的是,单矿物氧同位素组成显示出很大的变化范围,石英、石榴石、绿辉石的δ18O值分别为+11.40‰~+15.20‰,+3.59‰~+11.60‰和+8.30‰~+13.05‰,多硅白云母和蓝闪石δ18O的变化较小,分别为+10.00‰~+11.10‰和+9.26‰~+9.94‰.榴辉质岩石中高压变质矿物间氧同位素分馏广泛不平衡.全岩氧同位素组成特征表明,俯冲带深部流体主体来自邻近主岩,外来流体对氧同位素贡献有限.单矿物氧同位素广泛不平衡特征可能指示古俯冲带俯冲板片的快速俯冲和折返以及部分外来流体的参与. 相似文献
130.
南天山:晚古生代还是三叠纪碰撞造山带? 总被引:56,自引:42,他引:56
伊犁-哈萨克斯坦板块和塔里木-卡拉库姆板块之间的南天山造山带是‘中亚型造山带’的典型代表之一,经历了复杂的构造演化与地壳增生过程。传统上,它被视为华力西期褶皱带或晚古生代碰撞造山带。但近年来,部分学者提出它可能为三叠纪碰撞造山带。本文在综述南天山造山带的蛇绿岩、高压变质岩、花岗岩类等方面研究成果的基础上,讨论了其碰撞造山的时限。我国境内南天山西段碰撞造山可能开始于早石炭世(345Ma),结束于晚石炭世末(300Ma左右)。二叠纪时期,南天山至整个中亚地区进入后碰撞演化阶段。现有资料证实南天山为一晚古生代碰撞造山带,并非一三叠纪碰撞造山带。 相似文献