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Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan
Geological Journal ( IF 1.4 ) Pub Date : 2020-08-06 , DOI: 10.1002/gj.3952
Miao Sang 1, 2, 3 , Wenjiao Xiao 1, 2, 3 , Qinglai Feng 4 , Brian F. Windley 5
Affiliation  

Cherts, radiolarites, and radiolarian cherts are one of the most important components of accretionary complexes, and much used in the reconstruction of imbricated sections of ocean plate stratigraphy, and of the palaeogeographic and tectonic settings of ophiolitic mélanges. There has been little research on radiolarian cherts in the Kyrgyz South Tianshan, and the tectonic setting and temporal framework of the South Tianshan ocean are controversial. Here, we report well‐preserved radiolarians in ribbon‐bedded cherts in an ophiolitic mélange of the Atbashi accretionary complex (South Tianshan, Kyrgyzstan), which provide key evidence of ambient Palaeozoic oceanic conditions. The hydrofluoric acid technique was used to extract from the cherty rocks siliceous radiolarian, which yielded an age of late Early Carboniferous. Analyses of major, trace, and rare‐earth elements of four cherts indicate they are biogenic and deposited with little hydrothermal influence in a hemipelagic to continental margin environment. Our fossil ages and geochemical results of the radiolarian cherts from the Atbashi accretionary complex indicate that the South Tianshan ocean was still open in the Late Carboniferous, implying that it was a wide, long‐lived, major ocean that closed by northward subduction.

中文翻译:

吉尔吉斯南天山Atbashi增生复合体的硅质岩的放射虫年龄和地球化学

石,放射虫和放射l石是增生复合物最重要的组成部分之一,在重建海床地层的带状带的断层以及石质混杂岩的古地理和构造环境中被大量使用。吉尔吉斯斯坦南天山的放射虫石很少有研究,而南天山海洋的构造背景和时间框架尚有争议。在这里,我们报道了Atbashi增生复合体(吉尔吉斯斯坦南天山)的一片滑石质混杂岩中带状石中保存完好的放射虫,这提供了周围古生代海洋条件的关键证据。氢氟酸技术被用于从硅质岩中提取硅质放射虫,产生了早于石炭纪的年龄。专业,痕迹,四个石的稀土元素表明它们是生物成因的,并且在半地中海到大陆边缘环境中几乎没有热液作用沉积。我们的化石年龄和Atbashi增生复合体的放射状石的地球化学结果表明,南天山海在石炭纪晚期仍处于开放状态,这意味着它是一个宽阔,长寿的主要海洋,但被北俯冲所封闭。
更新日期:2020-08-06
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