(Table T1) Trace-element abundances for igneous basement at ODP Site 206-1256@en

In this report, I present trace element data for basement samples at Ocean Drilling Program (ODP) Site 1256. The samples analyzed represent a subset of the group (\"pool\") samples from ODP Leg 206, and these trace element data are part of a more comprehensive data suite for the same samples, with analyses of stable and radiogenic isotopes (e.g., Sr, Li, and O) in progress or recently completed that will be presented elsewhere. The trace element analyses were performed in the GeoAnalytical Lab at Washington State University. The following elements were analyzed: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ba, Th, Nb, Y, Hf, Ta, U, Pb, Rb, Cs, Sr, Sc, and Zr. Trace element data indicate that the igneous basement at Site 1256 is geochemically normal mid-ocean-ridge basalt. A massive ponded flow sampled in both Holes 1256C and 1256D is distinguished by higher abundances of rare earth elements (REE) and most of the other trace elements analyzed. One interval of highly altered basalt has significantly higher concentrations of Cs, Rb, and Ba and lower concentrations of Sr, Pb, Zr, Hf, Sc, and most REE than the samples of background alteration or halos. No correlation is obvious between trace element abundance and macroscopic type of alteration within the background alteration or halos.

本报告呈现大洋钻探计划（Ocean Drilling Program，ODP）1256站位基底样品的微量元素数据。本次分析的样品为大洋钻探计划第206航次组（"pool"）样品的一个子集，且该微量元素数据是对应样品完整数据集的一部分；针对这些样品的稳定同位素与放射成因同位素（如Sr、Li、O）分析工作正在进行或已近期完成，相关成果将在其他文献中发表。本次微量元素分析工作由华盛顿州立大学（Washington State University）地质分析实验室（GeoAnalytical Lab）完成。本次分析的元素包括：镧（La）、铈（Ce）、镨（Pr）、钕（Nd）、钐（Sm）、铕（Eu）、钆（Gd）、铽（Tb）、镝（Dy）、钬（Ho）、铒（Er）、铥（Tm）、镱（Yb）、镥（Lu）、钡（Ba）、钍（Th）、铌（Nb）、钇（Y）、铪（Hf）、钽（Ta）、铀（U）、铅（Pb）、铷（Rb）、铯（Cs）、锶（Sr）、钪（Sc）与锆（Zr）。微量元素数据表明，1256站位的火成基底地球化学特征属于正常洋中脊玄武岩。在1256C号钻孔与1256D号钻孔中均取样的巨厚池状熔岩流，其稀土元素（rare earth elements，REE）与本次分析的多数其他微量元素丰度均显著更高。一处强蚀变玄武岩层段的Cs、Rb与Ba含量显著高于背景蚀变样品或蚀变晕样品，而Sr、Pb、Zr、Hf、Sc以及多数稀土元素的含量则更低。在背景蚀变或蚀变晕范围内，微量元素丰度与宏观蚀变类型之间未呈现明显相关性。