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A sulfur isotope study of granitic plutons in the Great Basin, Western United States: Implications for magma-crust interaction and crustal architecture.

机译:美国西部大盆地花岗岩岩体的硫同位素研究:对岩浆-地壳相互作用和地壳构造的影响。

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摘要

Sulfur isotope data from Jurassic, Cretaceous, and Tertiary plutons provide important information about the crustal architecture of the Great Basin, which complements interpretations developed using other isotopic systems (i.e., Sr, Pb, Nd, O). Major-element geochemical analyses and whole-rock sulfur isotope analyses were conducted for 283 granitoid samples collected in the Great Basin. Rock geochemistry data indicate that the samples are dominantly metaluminous, I-type granitoids. Values of Aluminum Saturation Index [ASI = molar Al 2O3/(CaO + Na2O + K2O)] are predominantly very close to the metaluminous/peraluminous boundary, and the distribution of values is fundamentally the same for each age group. 8345 values range from -3.2 to +20.7‰, with a mean value of +6.4‰. There is little difference in the 6345 ranges and mean values among each of the three age categories. In addition to sulfur, oxygen isotope data were obtained on quartz from a subset of the pluton samples, and these data combined with the data of King et al. (2004) range from +4.8‰ to +13.5‰, with a mean value of +10.0‰.; Kriged maps of ASI, delta34S, and delta 18O values show very similar patterns in which the highest isotope and ASI values occurs in eastern Nevada, forming a circular high with lower values on all sides. The similarity in kriged patterns suggests that plutons in east central Nevada, and likely throughout the Great Basin, were generated as the result of crustal anatexis rather than through contamination of an ascending mantle melt. These patterns further indicate that the Great Basin can be separated into four distinct crustal domains, thus clarifying the crustal architecture of the region.
机译:来自侏罗纪,白垩纪和第三纪p的硫同位素数据提供了有关大盆地地壳构造的重要信息,这补充了使用其他同位素系统(即Sr,Pb,Nd,O)开发的解释。对大盆地采集的283个花岗岩样进行了主要元素地球化学分析和全岩硫同位素分析。岩石地球化学数据表明,这些样品主要是金属性的I型花岗岩。铝饱和指数的值[ASI =摩尔Al 2O3 /(CaO + Na2O + K2O)]主要非常接近金属/铝边界,并且每个年龄组的值分布基本相同。 8345值的范围是-3.2至+ 20.7‰,平均值为+ 6.4‰。在这三个年龄类别中,每个6345范围和平均值之间几乎没有差异。除硫外,还从一部分子体样品中获得了石英上的氧同位素数据,并将这些数据与King等人的数据结合在一起。 (2004年)的范围为+ 4.8‰至+ 13.5‰,平均值为+ 10.0‰。 ASI,delta34S和delta 18O值的Kriged图显示出非常相似的模式,其中最高的同位素和ASI值出现在内华达州东部,形成圆形的高位,各边的值均较低。克雷格模式的相似性表明,内华达州东部中部以及整个大盆地中的p是地壳深层沉积的结果,而不是由于上升的地幔熔体的污染而产生的。这些模式进一步表明,大盆地可以分为四个不同的地壳区域,从而阐明了该地区的地壳结构。

著录项

  • 作者

    DeYoung, Susan.;

  • 作者单位

    University of Nevada, Reno.;

  • 授予单位 University of Nevada, Reno.;
  • 学科 Geology.; Geochemistry.
  • 学位 M.S.
  • 年度 2007
  • 页码 94 p.
  • 总页数 94
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;地质学;
  • 关键词

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