Zircon U-Pb-He double dating (ZDD) provides the opportunity to derive high temperature crystallization ages and low temperature cooling ages from the very same mineral grain, making it especially attractive for zircon provenance studies. We present the combination of in situ detrital zircon U-Pb-He double dating and Raman spectroscopy-based heavy mineral analysis on different tributaries of the Inn river system applying a new grain embedding technique. The Inn river catchment drains a well-studied complex nappe pile of the Eastern Alps exposing Austroalpine and Penninic crystalline basement rocks. Igneous formations of different emplacement ages, as well as various metasedimentary units, have experienced Alpine and diverse pre-Alpine metamorphic overprints. This makes the area ideally suited for testing the sensitivity and potential of ZDD for fingerprinting various lithologically contrasting units with contrasting thermal histories. Results demonstrate that both high- and low-temperature age distributions reflect the major sources and thermotectonic pulses, respectively. More specifically, the rocks of the Tauern Window with Miocene (U-Th)/He ages as well as the Permian metagranitoids from the Tauern and the Err-Bernina nappe in the uppermost Inn valley are recorded in the downstream Inn sample. The main mass of zircons in the lower Inn, however, derives from the Ötztal and Silvretta crystalline basement rock with Cadomian U-Pb and Cretaceous (U-Th)/He ages. The abundance of heavy minerals derived from metamafic formations shows no correlation to the area of such lithologies on the catchments and the different zircon fertility resulted in the overrepresentation of zircon U-Pb ages from the Variscan igneous suites.

中文翻译：

---

因河流域现代沙子的锆石 U-Pb-He 双重测年：评估复杂造山环境中的分辨率和潜力

锆石 U-Pb-He 双重测年 (ZDD) 提供了从同一矿物颗粒中推导出高温结晶年龄和低温冷却年龄的机会，使其对锆石来源研究特别有吸引力。我们采用新的颗粒嵌入技术，将原位碎屑锆石 U-Pb-He 双重测年与基于拉曼光谱的重矿物分析相结合，对因河系统的不同支流进行了重矿物分析。因河流域排出了东阿尔卑斯山经过充分研究的复杂推覆堆，暴露了南高山和本宁结晶基底岩石。不同侵位年龄的火成岩地层以及各种变沉积岩单元经历了高山和多种前高山变质叠印。这使得该区域非常适合测试 ZDD 的灵敏度和潜力，以对具有对比热历史的各种岩性对比单元进行指纹识别。结果表明，高温和低温年龄分布分别反映了主要来源和热构造脉冲。更具体地说，具有中新世 (U-Th)/He 年龄的 Tauern Window 岩石以及来自 Tauern 和最上部 Inn 山谷的 Err-Bernina 推覆体的二叠纪变花岗岩都记录在下游 Inn 样本中。然而，Inn 下部的锆石主要来自 Ötztal 和 Silvretta 结晶基岩，具有卡多纪 U-Pb 和白垩纪 (U-Th)/He 年龄。来自变镁铁岩地层的重矿物丰度与流域内此类岩性的面积没有相关性，并且不同的锆石肥力导致 Variscan 火成岩套中的锆石 U-Pb 年龄被过度代表。