Provenance and tectonic setting of the Upper Palaeozoic sandstones in western Inner Mongolia (the Shalazhashan and Solonker belts), China: insights from detrital zircon U–Pb ages and Hf isotopes
Provenance and tectonic setting of the Upper Palaeozoic sandstones in western Inner Mongolia (the Shalazhashan and Solonker belts), China: insights from detrital zircon U–Pb ages and Hf isotopes
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中国内蒙古西部（沙拉扎山和索伦克带）上古生界砂岩的物源和构造背景：来自碎屑锆石U-Pb年龄和Hf同位素的见解
DOI：
10.1017/s0016756817000978
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发表时间：
2017-12
影响因子：
2.3
通讯作者：
Li ben
中科院分区：
文献类型：
--
作者：
Shi Guanzhong;Song Guangzeng;Wang Hua;Huang Chuanyan;Li ben
Solonker和Shalazhashan带是中亚造山带中备受争议的构造单元，因为它们既可能代表着中亚造山带的二叠纪或三叠纪缝合带，也可能是叠加在早古生代造山带上的裂谷带。这些带中上古生界砂岩的物源分析可为这一问题提供有益的制约。本研究在三个研究区（Solonker带的满都拉地区、靠近阿拉善地块的沙拉扎山带的曲干曲鲁地区和沙拉扎山带的恩格尔乌斯地区）采集了六个砂岩样品，进行了岩石骨架学、锆石形态、U-Pb和Lu-Hf同位素分析。框架岩相学表明，曼杜拉和恩格尔乌斯地区的样品含有高比例的火山碎屑，而Quagan Qulu地区的样品不仅包括火山碎屑，而且还包括大量的黑云母和白云母。Mandula地区和恩格尔.Us地区的碎屑锆石有两个主要年龄组：（1）260 ~ 330 Ma，εHf（t）值主要为-5 ~+12; (ii)早古生代弧源岩浆岩和晚古生代同沉积火山岩为主要烃源岩。查干曲鲁地区碎屑锆石具有一个420 × 500 Ma的主年龄组，部分年龄组为0.9 × 1.1 Ga、1.4 × 1.5 Ga、1.8 × 1.9 Ga和1.25 Ga，它们来自阿拉善地块的北方边缘。上古生界砂岩的岩性和化石组合表明深水沉积环境和向北加深的过渡。shallowmarine.to根据锆石光谱、沉积环境分析和前人的研究成果，我们认为，中国奥陶系索隆克带和沙拉扎山带是弧前或裂谷背景下的伸展盆地。
The Solonker and Shalazhashan belts are hotly debated tectonic units of the Central Asian.Orogenic Belt (CAOB), because they may either represent a Permian or Triassic suture zone of the.CAOB, or a rifting zone overprinted on an Early Palaeozoic orogen. Provenance analysis of the Upper.Palaeozoic sandstones in these belts may provide useful constraints on this issue. This study collected.six sandstone samples from three study areas: the Mandula area of the Solonker Belt, the Quagan Qulu.area of the Shalazhashan Belt but close to the Alxa block, and the Enger Us area of the Shalazhashan.Belt, for framework petrography, zircon morphology, U–Pb and Lu–Hf isotopic analyses. Framework.petrography reveals that the Mandula and Enger Us area samples contain high proportions of volcanic.fragments, whereas the samples from the Quagan Qulu area include not only volcanic fragments but.also significant amounts of biotite and muscovite. The detrital zircons of the Mandula area and the Enger.Us area yield two main age groups: (i) 260 ̶330 Ma, with dominant εHf(t) values of –5 to +12; and.(ii) 420 ̶550 Ma, with dominant εHf(t) values of –9 to +9, suggesting that Early Palaeozoic arc-related.magmatic rocks and Late Palaeozoic syn-depositional volcanic rocks are the main source rocks. The.detrital zircons of the Quagan Qulu area have one main age group of 420 ̶500 Ma and some grains of.0.9 ̶1.1 Ga, 1.4 ̶1.5 Ga, 1.8 ̶1.9 Ga and ∼ 2.5 Ga, which derive from the northern margin of the Alxa.block. The lithological and fossil assemblages of the Upper Palaeozoic sandstones suggest shallowmarine.to deep-water depositional environments and a northward-deepening transition. Based on the.zircon spectra, sedimentary environment analysis and previous studies, we argue that the Solonker.Belt and the Shalazhashan Belt of the CAOB are in extensional basins of a fore-arc or rifting setting.
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DOI：
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发表时间：
2010
期刊：
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影响因子：
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Geng Yuan-sheng
通讯作者：
Geng Yuan-sheng
DOI：
10.1146/annurev-earth-060614-105254
发表时间：
2015-06
影响因子：
14.9
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