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941.
DENG Jun FANG Yun YANG Liqiang YANG Junchen SUN Zhongshi WANG Jianping DING Shijiang WANG QingfeiChina University of Geosciences Beijing China University of Geosciences Wuhan Institute of Geology Geophysics Chinese Academy of Sciences Beijing Jilin University Changchun 《《地质学报》英文版》2001,75(2):220-232
Based on an analysis of the fractal structures and mass transport mechanism of typical shear-fluid-ore formation system, the fractal dispersion theory of the fluid system was used in the dynamic study of the ore formation system. The model of point-source diffusive illuviation of the shear-fluid-ore formation system was constructed, and the numerical simulation of dynamics of the ore formation system was finished. The result shows that: (1) The metallogenic system have nested fractal structure. Different fractal dimension values in different systems show unbalance and inhomogeneity of ore-forming processes in the geohistory. It is an important parameter to symbolize the process of remobilization and accumulation of ore-forming materials. Also it can indicate the dynamics of the metallogenic system quantitatively to some extent. (2) In essence, the fractal dispersive ore-forming dynamics is a combination of multi-processes dominated by fluid dynamics and supplemented by molecule dispersion in fluids and 相似文献
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通过对乌鲁木齐市区域水文地质,实测水化学资料及前人有关地下水水化学研究成果,总结了市区地下水水化学变化规律,同时对1996-2000年乌鲁木齐市地下水环境质量状况进行了水文地质化学综合评价。结果表明,1996-2000年间乌鲁木齐地下水污染面积减少,污染程度减轻,水体质量好转,地下水环境状况有明显改善。这一结果与近年来政府环境保护政策的贯彻落实,及各部门采取的防止地下水污染措施密切相关。 相似文献
946.
萨瓦亚尔顿金矿床成矿物质来源的初步探讨 总被引:1,自引:1,他引:1
萨瓦亚尔顿金矿床成矿物质具有多源性。资料显示,主成矿元素金一部分来自矿区容矿地层,另一部分来自下伏地层,矿质S和C主要来自深部,特别是下伏火山岩;Pb来自于造山带。成矿溶液主要来自以大气降水为补给的地下(卤)水。 相似文献
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948.
Plagioclase separates from the Layered Series (LS), Upper Border Series (UBS), and Marginal Border Series (MBS) of the Skaergaard
intrusion were analyzed to examine major and trace element variations. In general, plagioclase from the LS, UBS, and MBS show
similar trends in major elements vs. crystallization: SiO2, Na2O, and K2O progressively increase, and CaO and MgO progressively decrease with fractionation. No abrupt changes in the trends of major
components of Skaergaard plagioclase during the differentiation of the intrusion are observed. Trace elements in plagioclase
reflect changes in the Skaergaard magma and changes in plagioclase distribution coefficients with differentiation. Sr, Ga,
and probably Ba are included elements in Skaergaard plagioclase, but were excluded from the other cumulus phases, and as a
result systematically increased in the magma and plagioclase during differentiation. Be, Cs, Hf, Rb, Ta, U, and Zr, and the
transition metals Co, Cr, Cu, Ni, Sc, V, and Zn were excluded elements in Skaergaard plagioclase, and remained low in plagioclase
during differentiation. Changes in the abundances of these elements in plagioclase during differentiation reflect changes
in their abundance in the magma. With the exception of the lower zone, which is enriched in the light rare earth elements,
rare earth elements in LS plagioclase, in general, increase with differentiation of the Skaergaard intrusion, but decrease
dramatically at the UZa/UZb boundary where abundant apatite first appears. Rare earth elements in UBS plagioclase followed
a similar trend to LS plagioclase, except during the initial and final stages of differentiation. UBS plagioclase is much
more enriched in rare earth elements during the final 20% of crystallization, except for Eu, which is similar in plagioclase
from the two series. The observed trends suggest that the floor and roof sequences became isolated from each other and that
the floor sequence may have been more reducing and the roof sequence more oxidizing during the final 20% of crystallization.
As the Skaergaard magma ceased convection, or convected as isolated cells, during the final stages of differentiation, volatile
elements may have accumulated in the UBS magma, resulting in an increase in ƒO2, and a decrease in Eu/Sm in UBS plagioclase. The observed trends of rare earth elements in plagioclase from the LS and UBS
fit well with theoretical calculations that assume closed-system crystallization, and would be difficult to reconcile with
any model requiring significant discharge of magma from the chamber during the final 20% of crystallization. The enrichment
of light rare earth elements in plagioclase, suggests that the lower part of the intrusion re-equilibrated with a late, light
rare earth element-rich fluid or melt. The recharge model proposed by earlier workers to explain anomalous Sr and Nd isotopes
appears unlikely in light of the two to fourfold enrichment of light rare earth elements in these samples.
Received: 1 October 1999 / Accepted: 14 May 2000 相似文献
949.
950.
秦岭—巴山地区成矿背景和成矿作用的新进展 总被引:3,自引:1,他引:3
“八五”-“九五”期间秦岭的多项研究中,主要取得以下新进展:1.创立了抽拉-塑夺片构造新理论,丰富和发展了岩石圈板块或壳块运动方式的多样性。2.发现了东西向的秦岭造山带从显生宙以来有南北向的隆升带和沉积盆地,特别是太白、宝鸡-佛坪-汉南隆升带的发现,将从根本上改变秦岭乃至中国中东部构造格架的认识。3.南北向沉积盆地转谈东西向造山带的Ⅱ型造山带,深部构造岩片抽拉-逆冲推覆在中(新)生代陆相沉积盆地之上所形成的Ⅲ型造山带,为地壳表层增添了两种新型的造山带。4.首次提出秦岭造山带中存在三类沉积盆地,三种盆-山转换,三个发展阶段及三种型式(Ⅰ,Ⅱ,Ⅲ)的造山带,这在国内外均属首创。5.重新厚定商丹带、勉略带和二郎坪带的构造属性,形成时代,首次提出秦岭受三种体制,四个发展阶段的新观点,受抽拉构造形成的陆内造山带是秦岭最重要的划时代发展阶段。6.最先提出立交桥式结构观点。7.发现了一批前震旦系变质地层结晶岩系,重新厚定了一些地层的时代,特别是西秦岭,西成铅锌矿田中元古界地层的发现和超大型厂坝矿床产于其中,有重大的理论和实际意义。8.提出准浊流态流体的新概念。9.创立了在统一地质-成矿场制约下的多重岩片控矿论和构造一成矿体系,首次在秦岭提出三种统一地质-成矿场,三大构造一成矿体系,三种矿床模式及三种区域找矿模式。10.首次在秦岭提出超大型矿床的富集部位,大型矿床受鞘褶皱控制的观点。11.对若干矿床的成因提出新认识,特别是西成铅锌矿床,漳腊金矿床的新认识有重大的指导作用。12.划分出三级成矿远景区三个,四级远景区十三个,五级远景区:A级11个,B级9个,C级7个,还提出10个寻找大型矿床和穆龙套式金矿的地区。 相似文献