Qimantage terrestrial volcanics: petrologic evidence of active continental margin of Tarim Plate during late Indo-China epoch.
文献类型：期刊论文
| 作者 | Liu, HT |
| 刊名 | ACTA PETROLOGICA SINICA
 |
| 出版日期 | 2001-07-01 |
| 卷号 | 17期号:3页码:337-351 |
| 关键词 | calc-alkaline volcanics geochemistry whole-rock Rb-Sr isochron ages active continental margin Qimantago Kunlun |
| ISSN号 | 1000-0569 |
| 英文摘要 | The Qimantage terrestrial volcanic suite (QTVS) of late Triassic age lies in the middle segment of the Qimantage Mt. region, the Kunlun orogenic belt that extends along the northern margin of the Tibetan plateau, western China. The QTVS is dominated by dacite to rhyolite lavas and minor basaltic andesite and andesite, with vast accumulations of pyroclastic rocks (including ignimbrites, volcanic breccias and agglomerates) of dacitic and rhyolitic compositions. Petrological and geochemical studies indicate that the volcanic rocks are of typical calc-alkaline character (alkali-lime index is about 59) with silica contents ranging between similar to 53 and similar to 80 wt% and display relatively high-K feature. Major element variations for the volcanic rocks define rather smooth compositional trends, and compatible elements, such as MgO, Al2O3, Fe2O3 and CaO, decrease in a linear manner with silica contents. Large ion lithophile elements, such as alkalis, correlate positively with SiO2. Relative variations in trace element abundances on the chondrite-normalized data show high Rb, Ba and Th relative to other trace elements and Nb and Ti are depleted. Compatible trace elements, such as Ni, V and Co, as well as some incompatible trace elements such as Th, Tag Nb and Sr, diminish with increasing differentiation, while other trace elements (e.g. Rb, La and Ce) generally show increasing trends with the increasing silica contents. The chondrite-normalized REE patterns for different rocks of the QTVS are pseudo-paralleled to each other and exhibit highly fractionated LREE/HREE spectra with small to pronounced negative Eu anomalies indicating plagioclase-involving fractional crystallization was also well developed in crustal differentiation. Two whole-rock Rb-Sr isochrons yield ages of ca. 208 and ca. 222 Ma respectively, indicating the volcanic rocks were formed during the late Triassic. The isotope signatures of initial Sr-87/Sr-86 ratios ranging from similar to0.708 to similar to0.709 and initial epsilon (Nd) (t) values ranging from -2.09 to -2.36 imply that the magma was derived from crustal sources or mixed crustal-mantal sources. It has been recognized that the volcanic suite is underlain by pre-Triassic metamorphic and non-metamorphic sequences including the Precambrian crystalline basement. In combination of the geochemical and isotopic characteristics of the volcanics rocks with regional geologic setting, it is proposed that the QTVS was formed upon an active continental margin during the late Triassic north-directed subducting event. Both the volcanics and the closely-related coeval granitoid plutons collectively make up the late Triassic arc magmatic belt on the paleogeographically southern margin of the Tarim continent. Therefore, the QTVS is an essential component of the Kunlun orogenic belt. |
| 语种 | 英语 |
| WOS记录号 | WOS:000170244300001 |
| 出版者 | SCIENCE PRESS |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/76817]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Liu, HT |
| 作者单位 | Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China |
| 推荐引用方式 GB/T 7714 | Liu, HT. Qimantage terrestrial volcanics: petrologic evidence of active continental margin of Tarim Plate during late Indo-China epoch.[J]. ACTA PETROLOGICA SINICA,2001,17(3):337-351. |
| APA | Liu, HT.(2001).Qimantage terrestrial volcanics: petrologic evidence of active continental margin of Tarim Plate during late Indo-China epoch..ACTA PETROLOGICA SINICA,17(3),337-351. |
| MLA | Liu, HT."Qimantage terrestrial volcanics: petrologic evidence of active continental margin of Tarim Plate during late Indo-China epoch.".ACTA PETROLOGICA SINICA 17.3(2001):337-351. |
入库方式： OAI收割
来源：地质与地球物理研究所
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