Abstract

Ditrital zircon U-Pb and Lu-Hf isotopic data are reported for metaterrigenous deposits of Dzhagdy Terrane in the Mongol–Okhotsk Fold Belt. The youngest zircon populations in metasedimentary rocks of the Dzheskogon and Nekter formations is concluded to be of the Middle–Late Triassic and Early Jurassic Age, suggesting that the formations are Early Mesozoic and not Carboniferous, as was previously assumed. We have made the assumption that the Dzheskogon, Nekter, and Bochagor formations of the Dzhagdy Terrane are not a single sedimentary sequence, but a set of tectonic slices consisting of Late Paleozoic and Early Mesozoic rocks of differing genesis. This raises the question on whether the terrane under consideration is a fragment of an accretionary prism. Detrital zircon U-Pb geochronological and Lu-Hf isotopic data coupled with whole-rock Sm-Nd isotopic data from previous studies indicate that the sedimentary basin was mainly sourced from the continental Amur Superterrane (from the south in present-day coordinates). Material replenishment from the southern framing of the North Asian Craton (from the north in present-day coordinates) was either minimal or absent.

中文翻译：

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蒙古-鄂霍次克褶皱带Dzhagdy地层沉积沉积岩的年龄和来源：碎屑锆石U-Pb和Lu-Hf同位素数据

摘要

据报道蒙古-鄂霍次克褶皱带Dzhagdy Terrane的陆源锆石U-Pb和Lu-Hf同位素数据。得出结论，Dzheskogon和Nekter地层的沉积沉积岩中最年轻的锆石种群为三叠纪中晚期和侏罗纪早期，表明这些地层是中生代而不是石炭纪。我们假设Dzhagdy地层的Dzheskogon，Nekter和Bochagor地层不是单一的沉积层序，而是一组由不同成因的晚古生代和早中生代岩石组成的构造薄片。这就提出了一个问题，即所考虑的地球是否是增生棱镜的碎片。先前研究的碎屑锆石U-Pb年代学和Lu-Hf同位素数据以及全岩Sm-Nd同位素数据表明，沉积盆地主要来自大陆阿穆尔河超地层（在今天的坐标中是南部）。北亚克拉通南部框架（目前坐标中的北部）的物质补充很少或没有。