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31.
两广云开隆起区基性侵入岩的地球化学特征及其构造意义 总被引:8,自引:1,他引:8
云开隆起区信宜、高州一带条带-眼球状(环斑)花岗质岩石中基性侵入岩主要为变苏长辉长岩和变辉长岩,TiO2含量(0.24%~0.53%)和稀土元素总量(18.64~78.30μg/g)较低,轻稀土元素富集(LREE/HREE=2.69~5.28,(La/Yb)N=1.79~4.73),Ta、Nb、P、Zr、Ti为明显负异常,无明显Eu负异常(δEu=0.81~1.16),La/Nb=1.94~5.42,Th/Ta=2.29~17.63,Nb/Th<7.4,εNd(t)=-3.6~-8.4,高Ti/Zr、Ti/Y,低Rb/Ba、La/Yb和EMⅡ,显示富集地幔源区的特征.变苏长辉长岩Sm-Nd岩石-矿物同位素等时线年龄为392Ma±53Ma,表明加里东期的基性侵入岩形成于俯冲-碰撞大陆边缘的火山弧构造背景,而且是俯冲-碰撞后伸展-拆沉-底侵作用阶段的产物. 相似文献
32.
花岗岩类源岩与深部地质作用关系研究的若干进展 总被引:1,自引:0,他引:1
花岗岩类源岩研究是成岩成矿物质演化过程研究的基础,各种各样花岗岩的存在归因于花岗岩源岩存在多样性,在不同层圈发生交代,熔融,同化,混染作用;同时,成矿元素亦存在不同深度层圈的多来源,在花岗岩成岩成矿过程中,岩石圈地幔起着重要作用。 相似文献
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本文分析了下荆江系统裁弯前后入湖和出湖水、沙量的变化规律:分析了东、南洞庭湖淤积量的变化和淤积部位的变化,以及东、南洞庭湖的淤积趋势。 相似文献
35.
Digestion with aqua regia in Carius tube is commonly employed for determination of PGEs in geological samples. However, silicates cannot be completely dissolved by aqua regia and PGEs might partially remain in silicate residue. In this study, an ultramafic reference material was used to investigate the efficiencies of a new re-usable Carius tube after digestion at 220 and 240℃, and an autoclave-lined Carius tube at 260 and 280℃. The results show that about 10% of PGEs retained in the silicate residues at 220 and 5% still r℃ emains even digestion temperature increases to 280℃. These results agree with previous works that increasing the digestion pressure and temperature can achieve more effective dissolution. Thus, a modified digestion procedure for determination of PGEs in ultramafic rocks by the re-usable Carius tube was proposed in this study. 相似文献
36.
Changes in Chinese temperature extremes are presented based on a six-hourly surface air
temperature dataset for the period 1961--2005. These temperature series are manually observed at
0200, 0800, 1400, and 2000 Beijing Time (LST), and percentile based extreme indices of these time
series are chosen for analysis. Although there is a difference in time among the different time
zones across China, as more than 80% of the stations are located in two adjacent time zones,
these indices for all the stations are called warm (cold) nights (0200 LST), warm (cold) mornings
(0800 LST), warm (cold) days (1400 LST), and warm (cold) evenings (2000 LST), respectively for
convenience. The frequency of the annual warm extremes has generally increased, while the frequency
of the annual cold extremes has decreased, and significant changes are mainly observed in northern
China, the Tibetan Plateau, and the southernmost part of China. Based on the national average, annual
warm (cold) nights increase (decrease) at a rate of 5.66 (-5.92) d (10 yr)-1, annual warm (cold)
days increase (decrease) at a rate of 3.97 (-2.98) d (10 yr)-1, and the trends for the annual warm
(cold) mornings and evenings are 4.35 (-4.96) and 5.95 (-4.35) d (10 yr)-1, respectively. For
China as a whole, the increasing rates for the occurrence of seasonal warm extremes are larger in the
nighttime (0200, 2000 LST) than these in the daytime (0800, 1400 LST), the maximal increase occurs at
2000 LST except in the summer and the minimal increase occurs at 1400 LST except in autumn; the maximal
decrease in the occurrence of seasonal cold extremes occurs at 0200 LST and the minimal decrease occurs
at 1400 LST. 相似文献
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华南下石炭统为中国南部地区的主要含煤地层之一。据其聚煤期的先后、含煤性及其工业可采煤层等不同因素,划分为Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ聚煤期及8个聚煤区,并对有关存在争议地层的时空关系和化石带作了阐明。 相似文献
40.
New Chronological Evidence for Indosinian Diagenetic Mineralization in Eastern Xinjiang, NW China 总被引:7,自引:2,他引:7
LI Huaqin CHEN Fuwen LU Yuanf YANG Hongmei GUO Jing MEI Yuping Yichang Institute of Geology Mineral Resources Gangyao Ro Yichang Hubei 《《地质学报》英文版》2005,79(2):264-275
1 IntroductionMineralization in E. Xinjiang constitutes an importantpart of the Mid-Asian Metallogenetic Province. A greatdeal of nonferrous, ferrous, rare and noble metaldeposits of different genetic types and ages were formedduring different crustal evolution stages and werecontrolled by regional tectonic evolution. Large-scalemineralization of metallic deposits and relatedmagmatism mainly occurred during the Carboniferous toPermian periods (Li et al., 1998; Ji et al., 1999; Mao etal., 2… 相似文献