Abstract The genesis of high-silica igneous rocks is important for understanding the behavior of shallow magmatic systems. However, although many such studies have focused on the eruption of crystal-poor high-SiO2 rhyolites, the origin of high-silica granites (HSGs) has received comparatively little attention. Here, we present a detailed study of HSGs from the Narusongduo volcanic complex, Gangdese arc. Combining zircon U-Pb geochronology with stratigraphic investigations, we show that the Narusongduo magmatic system was constructed over a period of ≥3.7 Myr with or without lulls. On the basis of zircon textures and ages, diverse zircon populations, including antecrysts and autocrysts, are recognized within the HSGs and volcanic rocks. All of the igneous rocks within the Narusongduo volcanic complex have highly radiogenic Sr–Nd isotopic compositions. Our results indicate the presence of an andesitic magma reservoir in the upper crust at a paleodepth of ~8 km. Ubiquitous zircon antecrysts in the HSGs, combined with compositional similarities between the HSGs and evolved melts of the andesitic magma reservoir, indicate that the Narusongduo HSGs represent melts extracted from the shallow magma reservoir. In addition, our results suggest that magma recharge promoted the escape of high-silica melts to form the Narusongduo HSGs. This work presents an excellent case that kilometer-scale high-silica granites are the differentiated products from an upper crustal magma reservoir. It would make a contribution to contemporary debates concerning the efficiency of crystal–melt separation in upper crustal magmatic systems.

中文翻译：

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从上地壳岩浆储层中提取高硅花岗岩——来自冈底斯弧纳茹松多岩浆系统的见解

摘要 高硅火成岩的成因对于理解浅层岩浆系统的行为具有重要意义。然而，尽管许多此类研究都集中在晶体贫乏的高 SiO2 流纹岩的喷发上，但高硅花岗岩 (HSG) 的起源却相对较少受到关注。在这里，我们详细研究了冈底斯弧纳茹松多火山复合体的 HSG。结合锆石 U-Pb 年代学和地层调查，我们表明纳茹松多岩浆系统是在≥3.7 Myr 的时期内建造的，有或没有间歇。根据锆石的质地和年龄，在 HSG 和火山岩中识别出不同的锆石种群，包括先晶和自晶。纳茹松多火山杂岩中的所有火成岩都具有高放射成因的 Sr-Nd 同位素组成。我们的结果表明，在约 8 公里的古深度上地壳中存在安山质岩浆储层。HSGs 中无处不在的锆石原晶，结合 HSGs 和安山岩浆储层演化熔体之间的成分相似性，表明纳茹松多 HSGs 代表从浅层岩浆储层提取的熔体。此外，我们的结果表明，岩浆补给促进了高硅熔体逃逸，形成了纳茹松多 HSG。这项工作提供了一个很好的例子，公里级高硅花岗岩是上地壳岩浆储层的分化产物。