Australian National Radiogenic Isotope and Interpreted Ages Data Collection

Radiogenic isotopes decay at known rates and can be used to interpret ages for minerals, rocks and geologic processes. Different isotopic systems provide information related to different time periods and geologic processes, systems include: U-Pb and Ar/Ar, Sm-Nd, Pb-Pb, Lu-Hf, Rb-Sr and Re-Os isotopes. The GEOCHRON database stores full analytical U-Pb age data from Geoscience Australia's (GA) Sensitive High Resolution Ion Micro-Probe (SHRIMP) program. The ISOTOPE database is designed to expand GA's ability to deliver isotopic datasets, and stores compiled age and isotopic data from a range of published and unpublished (GA and non-GA) sources. OZCHRON is a depreciated predecessor to GEOCHRON and ISOTOPE, the information once available in OZCHRON is in the process of migration to the two current databases. The ISOTOPE compilation includes sample and bibliographic links through the A, FGDM, and GEOREF databases. The data structure currently supports summary ages (e.g., U-Pb and Ar/Ar) through the INTERPRETED_AGES tables, as well as extended system-specific tables for Sm-Nd, Pb-Pb, Lu-Hf and O- isotopes. The data structure is designed to be extensible to adapt to evolving requirements for the storage of isotopic data. ISOTOPE and the data holdings were initially developed as part of the Exploring for the Future (EFTF) program - particularly to support the delivery of an Isotopic Atlas of Australia. During development of ISOTOPE, some key considerations in compiling and storing diverse, multi-purpose isotopic datasets were developed: 1) Improved sample characterisation and bibliographic links. Often, the usefulness of an isotopic dataset is limited by the metadata available for the parent sample. Better harvesting of fundamental sample data (and better integration with related national datasets such as Australian Geological Provinces and the Australian Stratigraphic Units Database) simplifies the process of filtering an isotopic data compilation using spatial, geological and bibliographic criteria, as well as facilitating 'audits' targeting missing isotopic data. 2) Generalised, extensible structures for isotopic data. The need for system-specific tables for isotopic analyses does not preclude the development of generalised data-structures that reflect universal relationships. GA has modelled relational tables linking system-specific Sessions, Analyses, and interpreted data-Groups, which has proven adequate for all of the Isotopic Atlas layers developed thus far. 3) Dual delivery of 'derived' isotopic data. In some systems, it is critical to capture the published data (i.e. isotopic measurements and derived values, as presented by the original author) and generate an additional set of derived values from the same measurements, calculated using a single set of reference parameters (e.g. decay constant, depleted-mantle values, etc.) that permit 'normalised' portrayal of the data compilation-wide. 4) Flexibility in data delivery mode. In radiogenic isotope geochronology (e.g. U-Pb, Ar-Ar), careful compilation and attribution of 'interpreted ages' can meet the needs of much of the user-base, even without an explicit link to the constituent analyses. In contrast, isotope geochemistry (especially microbeam-based methods such as Lu-Hf via laser ablation) is usually focused on the individual measurements, without which interpreted 'sample-averages' have limited value. Data delivery should reflect key differences of this kind. Value: Used to provide ages and isotope geochemistry data for minerals, rocks and geologic processes. Scope: Australian jurisdictions and international collaborative programs involving Geoscience Australia

放射性同位素（radiogenic isotopes）以恒定速率衰变，可用于解析矿物、岩石及地质作用的形成年代。不同同位素体系对应不同的时间尺度与地质过程，涵盖的体系包括：U-Pb、Ar/Ar、Sm-Nd、Pb-Pb、Lu-Hf、Rb-Sr及Re-Os同位素体系。
GEOCHRON数据库存储了澳大利亚地质调查局（Geoscience Australia, GA）高灵敏度高分辨率离子微探针（Sensitive High Resolution Ion Micro-Probe, SHRIMP）项目的完整U-Pb定年分析数据。ISOTOPE数据库旨在拓展GA的同位素数据集交付能力，存储了来自一系列已发表及未发表（GA内部及非GA来源）的整合定年与同位素数据。OZCHRON是GEOCHRON与ISOTOPE的已废弃前身，原OZCHRON中的数据正逐步迁移至这两个现有数据库中。
ISOTOPE数据集通过A、FGDM及GEOREF数据库实现样品与文献的关联。当前数据结构通过INTERPRETED_AGES表支持汇总定年数据（如U-Pb与Ar/Ar体系），同时为Sm-Nd、Pb-Pb、Lu-Hf及O同位素体系提供扩展的专属系统表。该数据结构设计具备可扩展性，可适配同位素数据存储不断演进的需求。
ISOTOPE及其数据集最初作为“探索未来（Exploring for the Future, EFTF）”项目的一部分开发，尤其为支撑《澳大利亚同位素地图集》的交付工作。在ISOTOPE的开发过程中，针对多用途、多样化同位素数据集的整合与存储，形成了四项核心设计原则：
1. 优化样品表征与文献关联能力。同位素数据集的实用价值往往受限于其父样品的可用元数据。通过更全面地采集基础样品数据，并与澳大利亚地质省、澳大利亚地层单元数据库等相关国家级数据集进行更好的整合，可简化基于空间、地质及文献标准对同位素数据集进行筛选的流程，同时有助于针对缺失同位素数据开展“审计”工作。
2. 构建通用化、可扩展的同位素数据结构。针对同位素分析的专属系统表需求，并不妨碍能够反映通用关联关系的通用数据结构的开发。GA已构建了关联专属系统的测试、分析与解释数据组的关系型表结构，该结构已足够支撑目前已开发的所有同位素地图集图层。
3. 实现“衍生”同位素数据的双轨交付。在部分同位素体系中，同时留存原始发表数据（即原作者呈现的同位素测量值与衍生值），并通过一套统一的参考参数（如衰变常数、亏损地幔值等）从同一组测量数据中生成另一套衍生值，可实现全数据集范围内的“标准化”可视化呈现。
4. 提供灵活的数据交付模式。在放射性同位素定年领域（如U-Pb、Ar-Ar体系），即便未与原始组分分析数据建立显式关联，对“解释性定年”的精心整合与标注也可满足绝大多数用户的需求。而与之相对，同位素地球化学（尤其是基于微束的分析方法，如激光剥蚀Lu-Hf分析）通常以单次测量数据为核心，缺失原始测量数据的话，解释性“样品平均值”的实用价值将十分有限。因此数据交付模式应体现这类关键差异。
本数据集的价值：可为矿物、岩石及地质过程提供定年与同位素地球化学数据。适用范围：覆盖澳大利亚辖区及涉及澳大利亚地质调查局的国际合作项目。