瑞士洛桑大学Lukas P. Baumgartner小组报道了火成岩锆石中产生振荡带的枝晶生长机制。2024年11月20日出版的《地质学》发表了这项成果。

据介绍，火成岩锆石的同心振荡分带模式通常被解释为，岩浆结晶过程中岩心到岩缘生长的证据。这种解释为锆石年龄、化学和质地的各种定性和定量研究奠定了基础。

研究团队通过详细的微量元素图显示，具有明显典型阴极发光振荡带的自面体岩浆锆石，显示出树枝状生长的证据。这一观察结果对锆石振荡带的独特解释提出了挑战。

枝晶生长发生在大量过冷的条件下，导致锆石中微量元素浓度不平衡。具有这种生长历史的锆石的年代学和地球化学分析，需要一个不同的解释框架，这意味着岩浆和火山系统的时间尺度。

附：英文原文

Title: A dendritic growth mechanism for producing oscillatory zoning in igneous zircon

Author: Jack Gillespie, Benjamin Z. Klein, Jo Moore, Othmar Müntener, Lukas P. Baumgartner

Issue&Volume: 2024-11-20

Abstract: The concentric oscillatory zoning pattern of igneous zircon is generally interpreted as evidence for core to rim growth during magmatic crystallization. This interpretation anchors a wide variety of qualitative and quantitative studies of zircon age, chemistry, and texture. We show, via detailed trace element mapping, that euhedral magmatic zircon with apparently typical cathodoluminescence oscillatory zoning instead displays evidence of dendritic growth. This observation challenges the unique interpretation of oscillatory zoning in zircon. Dendritic growth occurs under conditions of substantial undercooling, resulting in disequilibrium trace element concentrations in the zircon. Geochronological and geochemical analyses of zircon with this type of growth history require a different interpretative framework, with implications for time scales of magmatic and volcanic systems.

DOI: 10.1130/G52641.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52641.1/650192/A-dendritic-growth-mechanism-for-producing