Provenance of Lower Cretaceous sediments in the Wandel Sea Basin, North Greenland

Detrital zircons in Lower Cretaceous sedimentary formations from the Wandel Sea Basin (Kilen, Peary Land) were dated by U–Pb and analysed for Hf isotopes by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Samples from Kilen and Peary Land display a wide range of U–Pb ages, with significant zircon populations at 1.0–1.1 and 1.8–2.0 Ga. Major hiati occur between 2.1 and 2.4 and from 0.48 to 0.91 Ga. Low initial ϵ_Hf values indicate that recycled crust components are significant in Caledonian-aged zircons, and in Palaeoproterozoic (1.8–2.0 Ga) and Neoarchaean zircon populations. Other U–Pb age populations in the studied samples are dominated by zircons with positive ϵ_Hf values indicating a significant contribution of mantle-derived material in these periods. A narrow range of ϵ_Hf values is commonly seen within a given U–Pb age population, and the values seen in the samples are in general correlated with the different age populations and their frequency. One exception is the 1.8–2.0 Ga population, where variations suggest variable sources. The U–Pb and Hf data are consistent with Greenland as the sole source of zircon from the studied sandstones.

对采自旺德尔海盆地（基伦、皮尔里地）下白垩统沉积地层的碎屑锆石开展了U-Pb定年，并通过激光剥蚀电感耦合等离子体质谱法（laser ablation inductively coupled plasma mass spectrometry，LA-ICP-MS）分析了其Hf同位素组成。采自基伦与皮尔里地的样品呈现出宽泛的U-Pb年龄分布，其中存在两个显著的锆石年龄群体，分别对应1.0~1.1 Ga和1.8~2.0 Ga两个区间。在2.1~2.4 Ga以及0.48~0.91 Ga区间存在明显的沉积间断。较低的初始ε_Hf值表明，加里东期锆石以及古元古代（1.8~2.0 Ga）和新太古代锆石群体中，再循环地壳组分占比显著。研究样品中的其余U-Pb年龄群体以具有正ε_Hf值的锆石为主，指示上述时期幔源物质的贡献占据重要比例。在特定的U-Pb年龄群体内，ε_Hf值通常呈现窄幅分布，且样品中的ε_Hf值总体上与不同年龄群体及其出现频率具有相关性。1.8~2.0 Ga年龄群体是一个例外，其ε_Hf值的变化暗示其物源具有不均一性。本次获取的U-Pb与Hf同位素数据表明，研究砂岩中的锆石仅以格陵兰作为唯一物源区。