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11.
运用电子探针和显微Fourier变换红外光谱技术,对新疆西天山3个榴辉岩样品中的石榴石进行了详细的主量元素和结构水分析。结果显示,石榴石发育以核部富锰铝榴石组分、边部富镁铝榴石组分进变质作用的成分环带。石榴石中OH^-1分布也具有规律:核部→边缘。其结构水OH^-1逐步增加,即从核部的89-239ppm增加到边部的367-658ppm;与石榴石边部相比,石榴石的核部含有较低的OH^-1,却含有较高的H2O和Mn含量。这表明,在蓝片岩向榴辉岩进变质作用过程中,含水矿物脱水反应而释放出大量的分子水,这部分水促进了高压变质反应,形成榴辉岩相矿物,石榴石核部的结晶就是在富水和Mn的条件下进行的。随着高压变质作用的继续,石榴石核部的分子水逐步失水而进入石榴石晶格,形成结构水。因此,在高压变质作用过程中,OH^-1演化实际上是一个由内部不平衡逐步向平衡转变过程。P588.348 相似文献
12.
The formal stereological transformation equation for particle sieve size distribution from measurements in lower dimensional spaces is applied to laser diffractometer measurements. The transformation function for iron ore particles is measured experimentally, and modeled. The solution is tested against the measured transformation function data as well as synthetic composite distributions of the original sample. The natural size distribution of a sample taken from a grinding circuit stream was measured by a combination of standard sieving and cyclosizer, and the result is compared to the transformed size distribution calculated from laser diffractometer measurements. The stereological transformation technique performed well in all cases. 相似文献
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Undulation and anomaly estimation using Geos-3 altimeter data without precise satellite orbits 总被引:1,自引:0,他引:1
The paper describes results obtained from the processing of 53 Geos-3 arcs of altimeter data obtained during the first weeks
after the launch of the satellite in April, 1975. The measurement from the satellite to the ocean surface was used to obtain
an approximate geoid undulation which was contaminated by long wavelength errors caused primarily by altimeter bias and orbit
error. This long wavelength error was reduced by fitting with a low degree polynomial the raw undulation data to the undulations
implied by the GEM 7 potential coefficients, in an adjustment process that included conditions on tracks that cross. The root
mean square crossover discrepancy before this adjustment was ±12.4 meters while after the adjustment it was ±0.9 m. These
adjusted undulations were used to construct a geoid map in the Geos-3 calibration area using a least squares filter to remove
remaining noise in the undulations. Comparing these undulations to ones computed from potential coefficients and terrestrial
gravity data indicates a mean difference of 0.25 m and a root mean square difference of ±1.92 m.
The adjusted undulations were also used to estimate several 5o, 2o, and 1o anomalies using the method of least squares collocation. The resulting predictions agreed well with known values although
the 1o x 1o anomalies could not be considered as reliably determined. 相似文献
15.
In the subduction complex of the Tianshan mountains, western China, massive blueschist is cross-cut by an eclogite-facies major fluid conduit surrounded by a reaction zone which is mainly composed of omphacite and garnet. Petrological as well as geochemical evidence suggest that formation of the vein and the eclogitic selvage around the vein was caused by fluid infiltration under peak metamorphic conditions of 21 ± 1.5 kbar and 510 ± 30 °C. The combination of whole-rock with mineral trace-element data as well as mass-balance calculations indicate that substantial differences exist between the unaltered host rock and the part of the system which was altered by fluid-rock interaction. These differences include: (1) depletion of mainly large-ion lithophile elements (LILE) and Li of up to 60% relative to their concentrations in the unaltered host rock; (2) an extreme enrichment of CaO (∼115%), Sr and Pb (>300%) in the altered parts of the vein-wall-rock system; (3) redistribution of heavy rare earth elements (HREE) from partly replaced rutile and recrystallized titanite in the blueschist-eclogite transition zone into newly grown garnet rims in the eclogitic selvage around the vein; (4) transformation of high Nb/Ta rutile into low Nb/Ta titanite which is associated with preferred mobilization of Nb over Ta; and (5) decoupling of Zr and Hf from Nb and Ta; the latter are depleted by ∼30% relative to the unaltered blueschist host rock whereas the former are depleted by only ∼10%. The prerequisite for the transformation of Ca-poor blueschist (6-7 wt.% CaO) into Ca-rich eclogite (up to 13 wt.% CaO) was the infiltration of a Ca-rich fluid. The release of trace elements can be attributed to partitioning of these elements into the passing fluid phase during dissolution-reprecipitation processes in the course of eclogitization. The reactivity of the precursor mineral assemblage and the chemical gradients between the reacting and passing fluid of the conduit are mainly responsible for trace-element mobilization in the studied samples. The suite of trace elements released upon fluid-induced eclogitization of the reactive wall-rock resembles that in island arc magmas showing strong enrichment of LIL elements, strong depletions in HFS elements and intermediate concentrations of REE. 相似文献
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The science requirements on future gravity satellite missions, following from the previous contributions of this issue, are
summarized and visualized in terms of spatial scales, temporal behaviour and accuracy. This summary serves the identification
of four classes of future satellite mission of potential interest: high-altitude monitoring, satellite-to-satellite tracking,
gradiometry, and formation flights. Within each class several variants are defined. The gravity recovery performance of each
of these ideal missions is simulated. Despite some simplifying assumptions, these error simulations result in guidelines as
to which type of mission fulfils which requirements best. 相似文献
19.
R. Rummel 《Earth, Moon, and Planets》2004,94(1-2):103-111
Planetology serves the understanding on the one hand of the solar system and on the other hand, for investigating similarities
and differences, of our own planet. While observational evidence about the outer planets is very limited, substantial datasets
exist for the terrestrial planets. Radar and optical images and detailed models of gravity and topography give an impressive
insight into the history, composition and dynamics of moon and planets. However, there exists still significant lack of data.
It is therefore recommended to equip all future satellite missions to the moon and to planets with full tensor gravity gradiometers
and radar altimeters. 相似文献
20.