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首页> 外文期刊>Contributions to Mineralogy and Petrology >Sub-micron scale distributions of trace elements in zircon
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Sub-micron scale distributions of trace elements in zircon

机译：锆石中微量元素的亚微米尺度分布

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Sub-micron scale zoning of Ti concentrations and correlations between concentrations of Ti and other trace elements (P, Ce, and Y) and cathodoluminescent (CL) banding is observed in natural zircons. Ion images were made using the Caltech Microanalysis Center's CAMECA NanoSIMS 50L with an O" primary beam focused to ~300 nm on the sample surface. The high spatial resolution of this technique allows for interrogation of chemical variations at or below the scale of CL banding in natural zircons. Images produced in this manner display two types of correlations among Ti, P, Ce, and Y (which appears to be a proxy for CL intensity): strong (correlation coefficients >0.8) and subtle (correlation coefficients ~0.15-0.4). Strongly correlated images, which display Ti variations of ca. a factor of 3 between adjacent CL bands and overall elevated trace element concentrations in CL-dark bands, were found within an oscillatory-zoned, trace element enriched sector of a CL sector-zoned zircon. Three possible causes for such correlations include: temperaturedependent equilibrium partitioning, trace element partitioning limited by diffusion in the host melt and surface-controlled, non-equilibrium growth. Comparison of our data with the expected results of these processes suggests that: (1) Ti partitioning in zircon is dependent upon non-equilibrium effects in addition to temperature and/or (2) the incorporation of elements that co-vary with Ti in zircon (e.g., Y, P and Ce) is also temperature-dependent. Sub-micron scale, high-Ti regions are also found within Pro-terozoic Adirondack and >4 Ga Jack Hills zircons as well as trace element enrichments (including Ti) along cracks within Jack Hills zircons.
机译：在天然锆石中观察到Ti浓度的亚微米级分区以及Ti和其他微量元素（P，Ce和Y）的浓度之间的相关性以及阴极发光（CL）带。离子图像是使用Caltech Microanalysis Center的CAMECA NanoSIMS 50L制成的，O形主光束聚焦在样品表面约300 nm处。该技术的高空间分辨率允许对CL谱带或以下的化学变化进行询问。以这种方式产生的图像显示出Ti，P，Ce和Y之间的两种相关性（似乎是CL强度的代表）：强（相关系数> 0.8）和微妙（相关系数〜0.15-0.4） ）。在一个震荡分区，微量元素富集的CL扇区中发现了高度相关的图像，这些图像显示相邻CL带之间的Ti变化约为3倍，并且CL-暗带中的痕量元素浓度总体升高。产生这种相关性的三个可能原因包括：温度相关的平衡分配，痕量元素分配受主体熔体中扩散的限制以及表面控制的非平衡生长wth。我们的数据与这些过程的预期结果的比较表明：（1）锆石中的钛分配还取决于温度以外的非平衡效应和/或（2）锆石中与Ti共变的元素的结合（例如，Y，P和Ce）也取决于温度。在元古代的阿迪朗达克和> 4 Ga Jack Hills锆石中还发现了亚微米级的高Ti区域，以及在Jack Hills锆石中沿裂缝的痕量元素富集（包括Ti）。

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