Interrogating the provenance of large river systems: multi-proxy in situ analyses in the Millstone Grit, Yorkshire
Interrogating the provenance of large river systems: multi-proxy in situ analyses in the Millstone Grit, Yorkshire
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DOI：
10.1144/jgs2016-069
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发表时间：
2016-10
影响因子：
2.7
通讯作者：
P. Lancaster;J. Daly;C. Storey;A. Morton
中科院分区：
文献类型：
--
作者：
P. Lancaster;J. Daly;C. Storey;A. Morton
确定沉积物质的来源对许多地质应用至关重要，但由于某些矿物的再循环能力而变得复杂。为了检验目前确定一个独特的物源代理的相对效用，新的样品已被收集从纳穆里安磨石砂砾组的约克郡，英格兰。两个钾长石206 Pb/204 Pb同位素群体介于12.5和15.5之间，c. 18.4分别与太古代-元古代基底和加里东期花岗岩相一致。c.锆石U-Pb年龄群2700、2000 - 1000和430 Ma反映了太古代基底、上覆元古宙沉积物和加里东期侵入花岗岩的混合体，各年龄锆石εHf值反映了改造地壳的结晶作用。石榴子石主要元素组成相对富含Fe和低Ca，表明其来源于麻粒岩或碳硅石。金红石Cr/Nb比值表明烃源岩主要为变细岩，金红石中的Zr测温记录了两个代表较低（c. 650°C）和更高（C。800°C）变质级材料。将这些结果与已发表的独居石和白云母数据相结合，表明总体来源于格陵兰喀里多尼亚，还有来自苏格兰东北部和挪威西部的额外贡献，凸显了多代理物源工作的力量，特别是在构造和地质复杂的地区。补充材料：样品详情、完整的分析方法、数据表和文本中汇编数字的参考资料可在https://doi.org/10.6084/m9.figshare.c.3515457上查阅。
Establishing the source(s) of sedimentary material is critical to many geological applications, but is complicated by the ability of some minerals to be recycled. To test the relative utility of current proxies for determining a unique provenance, new samples have been collected from the Namurian Millstone Grit Group of Yorkshire, England. Two K-feldspar 206Pb/204Pb isotope populations between 12.5 and 15.5 and c. 18.4 are consistent with Archaean–Proterozoic basement and Caledonian granites, respectively. Zircon U–Pb age populations at c. 2700, 2000 – 1000 and 430 Ma reflect a mixture of Archaean basement, overlying Proterozoic sediments and intrusive Caledonian granites, and εHf values in zircons of all ages indicate crystallization from reworked crust. Garnet major element compositions are relatively rich in Fe and low in Ca, indicative of derivation from a granulitic or charnockitic source. Rutile Cr/Nb ratios indicate that source rocks were dominantly metapelitic, and Zr-in-rutile thermometry records two populations representing lower (c. 650°C) and higher (c. 800°C) metamorphic grade material. Combining these results with published monazite and muscovite data suggests overall derivation from the Greenland Caledonides, with additional contributions from NE Scotland and western Norway, highlighting the power of multi-proxy provenance work, especially in tectonically and geologically complicated regions. Supplementary material: Sample details, full analytical methods, data tables and references for compilation figures in the text are available at https://doi.org/10.6084/m9.figshare.c.3515457.