Constraining depositional models in the Barents Sea region using detrital zircon U–Pb data from Mesozoic sediments in Svalbard

Detrital zircon U–Pb laser ablation inductively coupled plasma mass spectrometry age data on sandstones from Mesozoic successions on Svalbard are used to investigate provenance changes over time, constrain potential source areas, and to test and refine previous interpretations of the Mesozoic filling of the Barents Sea. The zircon age data indicate a western Laurentian (North Greenland) source in the Early and Middle Triassic. The westerly derived sediments most likely include reworked older sediments with proto-sources in Canada and Greenland. Sediments reaching Svalbard in the Late Triassic display a distinct Uralide signature that demonstrates derivation from the east. Zircon age populations in Late Triassic–Early Jurassic sands suggest mixing of zircons from the Early and Middle Triassic and Late Triassic sediments; the data are interpreted to reflect reworking of older Mesozoic sands and possible renewed input of sediments from the west. The data thus demonstrate a shift from westerly to easterly sediment sources in the early Late Triassic. The Early and Middle Triassic zircon age signature in this study appears to resurface in published Early Cretaceous provenance data from Svalbard, suggesting that sediment input from the east ceased during the Jurassic, and shifted back to westerly sources.

本数据集采用斯瓦尔巴（Svalbard）地区中生代地层砂岩的碎屑锆石U-Pb（Detrital zircon U–Pb）激光剥蚀电感耦合等离子体质谱法（laser ablation inductively coupled plasma mass spectrometry）定年数据，以探讨沉积物物源随时间的演化规律，限定潜在物源区，并对前人关于巴伦支海（Barents Sea）中生界沉积充填过程的解释进行验证与优化。锆石定年数据显示，早三叠世与中三叠世时期的沉积物物源来自劳伦大陆（Laurentian）西部（北格陵兰区域）。由西部搬运而来的沉积物大概率包含了源自加拿大与格陵兰原始物源区的再改造古沉积物。晚三叠世时期抵达斯瓦尔巴地区的沉积物呈现出显著的乌拉尔造山带（Uralide）特征，表明其物源来自东部区域。晚三叠世至早侏罗世砂岩中的锆石年龄种群表明，其锆石来自早-中三叠世与晚三叠世沉积物的混合；该数据被解读为反映了早中生代砂岩的再改造作用，以及可能来自西部的沉积物的新一轮补给。由此可见，在晚三叠世早期，沉积物物源发生了从西向东的转变。本研究中的早-中三叠世锆石年龄特征，在已发表的斯瓦尔巴地区早白垩世物源数据中再次出现，表明东部的沉积物补给在侏罗纪时期停止，物源重新转回西部。