Petrogenesis of Paleo-Mesoproterozoic mafic rocks in the southwestern Yangtze Block of South China: Implications for tectonic evolution and paleogeographic reconstruction
Petrogenesis of Paleo-Mesoproterozoic mafic rocks in the southwestern Yangtze Block of South China: Implications for tectonic evolution and paleogeographic reconstruction
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华南扬子地块西南部古中元古代基性岩岩石成因：构造演化与古地理重建的意义
DOI：
10.1016/j.precamres.2018.12.019
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发表时间：
2019-03
影响因子：
3.8
通讯作者：
Xue Er-Kun
中科院分区：
文献类型：
--
作者：
Lu Gui-Mei;Wang Wei;Ernst Richard;Söderlund Ulf;Lan Zu-Fan;Huang Si-Fang;Xue Er-Kun
利用锆石和斜锆石U-Pb定年方法，将扬子地块西南部的镁铁质岩浆活动划分为3期，分别为2299 ± 17 Ma、1703 ± 8 Ma和1511 ± 14 Ma。这些基性岩具有拉斑玄武岩成分，富集大离子亲石元素，但缺乏Nb、Ta、Zr、Hf异常，与E-MORB特征相似。它们的La/Ta（<22）和La/Nb（<1.5）比值与软流圈来源的镁铁质熔体相似。CA。2.3加，加利福尼亚州。1.7 Ga和ca。1.5 Ga基性岩石的εNd（t）值分别为+0.2至+4.3、-2.8至+2.8和+0.7至+5.8。此外，CA。2.3 Ga和ca。1.7 Ga基性岩石的εHf（t）值介于−3.6至+0.8和+0.1至+9.2之间。这些地球化学和同位素数据表明，研究的镁铁质岩可能主要来源于软流圈地幔。2.3 Ga和ca。1.7 Ga辉长岩的温度分别为1447 °C-1568 °C、1511 °C-1529 °C，表明扬子地块西南部的地幔温度相对较高，约为1500 ℃。2.3 Ga和ca。1.7佐治亚州REE模式表明，Ca。2.3 Ga和ca。1.5 Ga辉长岩是地幔源区低度熔融（3-15%）形成的，而Ca。1.7 Ga辉长岩来自地幔源区的不同程度熔融（0.5 ~ 20%）。橄榄石、辉石和斜长石的分馏作用改变了原始岩浆的化学成分，而地壳混染作用相对不明显。CA。2.3 Ga粗玄岩代表了扬子地块西南部迄今为止发现的最古老的镁铁质岩浆活动，记录了扬子地块从努纳武蒂亚超克拉通中的分散。比较不同地壳块体的较年轻岩浆条形码记录表明，约1000年的镁铁质岩浆作用。1.75-1.65 Ga在扬子地块，与西北劳伦蒂亚和西伯利亚南部。这一时期广泛的岩浆活动可能与哥伦比亚/努纳超大陆的早期分裂有关，表明该超大陆中这些大陆之间的紧密联系。
Three episodes of mafic magmatism are identified by zircon and baddeleyite U-Pb dating at 2299 ± 17 Ma, 1703 ± 8 Ma and 1511 ± 14 Ma in the southwestern Yangtze Block. These mafic rocks have tholeiitic compositions with enrichment of LILE but an absence of Nb, Ta, Zr, Hf anomalies, features similar to E-MORB. They have La/Ta (<22) and La/Nb (<1.5) ratios similar to asthenosphere-derived mafic melts. The ca. 2.3 Ga, ca. 1.7 Ga and ca. 1.5 Ga mafic rocks have εNd(t) values of +0.2 to +4.3, −2.8 to +2.8 and +0.7 to +5.8, respectively. Furthermore, the ca. 2.3 Ga and ca. 1.7 Ga mafic rocks have εHf(t) values varying from −3.6 to +0.8 and +0.1 to +9.2. All these geochemical and isotopic data indicate that the studied mafic rocks may be dominantly sourced from asthenospheric mantle.Thermodynamic modeling indicates that the mantle potential temperatures for the studied ca. 2.3 Ga and ca. 1.7 Ga dolerites are 1447 °C −1568 °C, 1511 °C −1529 °C, suggesting relatively hot mantle below the southwestern Yangtze Block at ca. 2.3 Ga and ca. 1.7 Ga. REE modeling indicates the ca. 2.3 Ga and ca. 1.5 Ga dolerites were generated by low degree melting (3–15%) of mantle source, while the ca. 1.7 Ga gabbros were derived from variable degree melting (∼5–20%) of mantle source. Fractionation of olivine, pyroxene and plagioclase contributes to changing the chemical compositions of the primary magma, while crustal contamination was relatively insignificant.These three episodes of mafic magmatism were generated in extensional setting. The ca. 2.3 Ga dolerite represents the oldest mafic magmatism identified in the southwestern Yangtze Block by far, documenting the dispersion of the Yangtze Block from the Nunavutia supercraton. Comparing the younger magmatic barcode records for various crustal blocks shows that the mafic magmatism at ca. 1.75–1.65 Ga in the Yangtze Block, has matches in northwestern Laurentia and southern Siberia. This period of extensive magmatism was presumably linked to the early attempted breakup of the Columbia/Nuna supercontinent, indicating tight linkage among these continents in that supercontinent.
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影响因子：
3.9
作者：
Gerstenberger, H;Haase, G
通讯作者：
Haase, G
DOI：
--
发表时间：
2014
期刊：
Journal of Mineralogy and Petrology
影响因子：
--
作者：
Ren Guang-min
通讯作者：
Ren Guang-min
影响因子：
3.9
作者：
P. Leat;R. Thompson;M. A. Morrison;G. Hendry;A. Dickin
通讯作者：
P. Leat;R. Thompson;M. A. Morrison;G. Hendry;A. Dickin
古元古代岩浆和变质事件将长江与努纳超大陆劳伦大陆西北部连接起来
影响因子：
5.3
作者：
Wang, Wei;Cawood, Peter A.;Zhou, Mei-Fu;Zhao, Jun-Hong
通讯作者：
Zhao, Jun-Hong
影响因子：
18.3
作者：
Brunelli, Daniele;Cipriani, Anna;Bonatti, Enrico
通讯作者：
Bonatti, Enrico