摘要
陕西省西乡县汉南杂岩望江山岩体辉长岩中含有丰富的锆石——从600kg辉长岩样品中分选出结晶良好、内部结构简单、成因和年龄单一、Hf同位素比值均一的锆石7g,锆石粒度多为0.2～0.3mm。分别在3个不同实验室利用3种方法对该锆石样品进行了U-Pb同位素年龄测定,获得了在误差范围内完全一致的年龄:819.8±2.5Ma(LA-ICP-MS)、821.7±1.7Ma(LA-MC-ICPMS)和822.1±4.5Ma(SHRIMP)。在国内4个权威实验室对该锆石进行了Lu-Hf同位素测定,获得了在误差范围内完全一致的176Hf/177Hf同位素比值——全部421个测试点加权平均值为0.282535±0.000003(2σ)。采样点岩体规模巨大,露头良好,岩石新鲜,交通方便。该锆石样品满足作为Hf同位素测定标样的各方面的指标,可能是一个比较理想的Hf同位素测定标样。Hf同位素测定标准物质的研制,是测定获得准确可靠的Hf同位素数据的基础,具有十分重要的实用价值和科学意义。
The Wangjiangshan gabbro in Hannan intrusive complex in Xixiang County, Shaanxi Province, contains abundant zircons. Seven grams of zircons separated from 600 kg of gabbro samples are good in crystallization, simple in internal structure and origin, homogenious in U-Pb age and Hf isotopic composition, with crystal sizes ranging from 0.2 to 0.3 mm. The U-Pb dating of the zircons was carried out in three different laboratories using three different methods; consistent ages obtained are 819.8 ± 2.5 Ma (LA-ICP-MS), 821.7 ± 1.7 Ma (LA-MC-ICPMS) and 822.1 ± 4.5 Ma (SHRIMP). The Lu-Hf isotopic compositions of the zircons were measured in four authoritative laboratories and consistent 176Hf/177Hf ratios were obtained, with the weighted average 176Hf/177Hf ratio of the total 421 analyses falling within 0.282535 ± 0.000003 (2σ). The gabbro sampled is well-outcropped, fresh, large in size, and convenient to access. This zircon sample collected from the Wangjiangshan gabbro has met major requirements for Hf analysis standard and can serve as a standard zircon for Hf analysis. Preparation of Hf isotopic standard material is the basis for obtaining accurate and reliable determination of Hf isotopic data and has very important practical value and scientific significance. .
出处
《地质学报》
EI
CAS
CSCD
北大核心
2013年第4期554-564,共11页
Acta Geologica Sinica
基金
中国地质调查局地质调查项目(编号:1212010916068)资助的成果
