当前位置: X-MOL 学术Lithos › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Petrogenesis of ~2.1 Ga mafic and granitic magmatism and tectonic implication of Jiaobei Terrane in North China Craton
Lithos ( IF 3.5 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.lithos.2020.105806
Xinping Wang , Chang Whan Oh , Peng Peng , Lei Zhao , Mingguo Zhai , Seung Hwan Lee

Abstract Paleoproterozoic magmatism in the Jiaobei Terrane has not been well studied, but it is important for understanding the tectonic evolution of Jiao-Liao-Ji belt in the east North China Craton. In this work, ~2.1 Ga mafic and granitic intrusions in the Jiaobei Terrane, including the Xiliu amphibolite, Dongbaishishan granite and Gujiacun granite, are studied in detail. The Xiliu amphibolite intruded the Archean basement and the Dongbaishishan granite intruded the Paleoproterozoic Jingshan Group. SHRIMP zircon U Pb geochronology shows that both amphibolite and granite were emplaced simultaneously at ~2.1 Ga and were metamorphosed at ~1.87–1.84 Ga. The ~2.1 Ga Xiliu amphibolite samples show a tholeiitic basalt composition; they exhibit enriched light rare earth elements (REEs) and large ion lithophile elements (LILEs, e.g., U and K), but depleted high field strength elements (HFSEs, e.g., Nb, Ta, P, Zr, Hf and Ti). They experienced the fractional crystallization of clinopyroxene. Whole-rock Nd isotopes show that the ~2.1 Ga amphibolites were generated from partial melting of the Archean enriched mantle, and that the mantle source was affected by the addition of subduction-related fluids/melts. The ~2.1 Ga Dongbaishishan and Gujiacun granite samples in the Jiaobei Terrane show granodiorite to granite compositions with metaluminous and calc-alkaline characteristics. They show decreasing Fe2O3T, TiO2, Al2O3, CaO, Na2O and P2O5, but increasing K2O, with increasing SiO2 contents. This indicates that Fe Ti oxide, plagioclase and apatite were fractionated during magmatic evolution, which is confirmed by the negative Eu, Sr, P, and Ti anomalies. Compared with the 2.18 Ga A-type granites derived from partial melting of tonalites in the Jiaobei Terrane, major elemental geochemistry and zircon Hf isotopes showed that ~2.1 Ga granites were generated from partial melting of the low-K mafic lower crust possibly due to mantle-derived magmatic underplating. The ~2.1 Ga Jiaobei amphibolites show similar geochemical and isotopic characteristics to the contemporaneous mafic rocks in the north Liaoji and south Anhui areas of the Jiao-Liao-Ji belt. Together with the volcano-sedimentary series and A2- and I-type granitic gneiss in the belt, these ~2.1 Ga mafic rocks probably formed in a subduction-related back-arc extension environment. In addition, both episodes of the 2.18 Ga and 2.1 Ga granites in the Jiaobei Terrane show high-temperature magmatic characters, which can be attributed to mantle-derived magmatic heating. The younger episode (2.1 Ga) granites indicate that there was stronger mantle-derived magmatism in a back-arc extended zone.

中文翻译:

华北克拉通胶北地体~2.1 Ga基性和花岗质岩浆作用的成因及构造意义

摘要 胶北地块的古元古代岩浆作用尚未得到很好的研究,但对于了解华北克拉通东部胶辽冀带的构造演化具有重要意义。在这项工作中,对焦北地体中~2.1 Ga 基性和花岗岩侵入体,包括西流角闪岩、东白石山花岗岩和古家村花岗岩进行了详细研究。西流角闪岩侵入太古代基底,东白石山花岗岩侵入古元古代景山群。SHRIMP 锆石 U Pb 年代学表明角闪岩和花岗岩在~2.1 Ga 处同时被侵位并在~1.87-1.84 Ga 处变质。~2.1 Ga 西柳角闪岩样品显示拉斑玄武岩组成;它们表现出富集的轻稀土元素 (REE) 和大离子亲石元素 (LILE,例如 U 和 K),但耗尽了高场强元素(HFSE,例如 Nb、Ta、P、Zr、Hf 和 Ti)。他们经历了单斜辉石的分级结晶。全岩 Nd 同位素表明~2.1 Ga 角闪岩是由太古代富集地幔的部分熔融产生的,并且地幔源受到与俯冲相关的流体/熔体的影响。胶北地体中~2.1 Ga 东白石山和古家村花岗岩样品显示花岗闪长岩至花岗岩组成,具有金属铝和钙碱性特征。它们显示出随着 SiO2 含量的增加,Fe2O3T、TiO2、Al2O3、CaO、Na2O 和 P2O5 减少,但 K2O 增加。这表明 Fe Ti 氧化物、斜长石和磷灰石在岩浆演化过程中被分馏,这被 Eu、Sr、P 和 Ti 的负异常所证实。与2相比。18 Ga A 型花岗岩来源于胶北地块的色调岩部分熔融,主要元素地球化学和锆石Hf 同位素表明~2.1 Ga 花岗岩是由低K 基性下地壳部分熔融产生的,可能是由于幔源岩浆作用底镀。~2.1嘎胶北角闪岩与胶辽冀地区辽吉北部和皖南地区的同时期基性岩具有相似的地球化学和同位素特征。连同火山沉积系列和带中的 A2 和 I 型花岗片麻岩,这些~2.1 Ga 基性岩可能形成于与俯冲相关的弧后伸展环境中。此外,胶北地块2.18 Ga和2.1 Ga花岗岩均表现出高温岩浆特征,这可以归因于地幔源岩浆加热。
更新日期:2020-12-01
down
wechat
bug