The volcanic-intrusive connection is critical for understanding the formation of transcrustal magma systems and the mechanisms driving magma eruption. Yet, the genetic links between abyssal intrusive rocks and acidic volcanic rocks remain poorly understood. Here, we present new data from the Dulan volcanic-intrusive complex, a tilted section of the East Kunlun orogenic belt, integrating zircon UPb dating, trace elements, apatite and zircon Hf isotope geochemistry, and whole-rock geochemistry to investigate volcanic-intrusive connections and track crystal-melt segregation processes. The Dulan complex comprises rhyolite, granite porphyry, and granodiorite, all showing consistent zircon UPb ages, rare earth element (REE) patterns, and εHf(t) values, suggesting a shared magma source. Glomerocrysts of plagioclase, alkali feldspar, and hornblende, along with antecrystic zircon and apatite, imply a cumulate affinity in granodiorite and granite porphyry. Compositional variations in whole-rock and accessory minerals indicate that plagioclase, apatite, and zircon fractionation significantly influenced magma evolution. We propose a two-stage crystal segregation process in a ∼ 2 Myr-long magma reservoir system. In the early stage, at ∼33 km depth, aqueous fluid influx initiated crystal-melt segregation, forming the Dulan granodiorite from residual mush. In the later stage, mafic melt and fluid injections caused crystal-melt segregation in a shallower reservoir at ∼12 km depth, with high-silica magma producing rhyolite, while residual mush consolidated into granite porphyry. Our findings suggest that volcanic-intrusive connections are more complex than mere compositional equivalence or complementarity, requiring multidimensional analysis through accessory minerals and whole-rock geochemistry.

中文翻译：

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杜兰倾斜地壳剖面的火山-侵入连接和晶体-熔体偏析：来自辅助矿物演化的见解


火山-侵入式联系对于理解跨地壳岩浆系统的形成和驱动岩浆喷发的机制至关重要。然而，深海侵入岩和酸性火山岩之间的遗传联系仍然知之甚少。在这里，我们展示了来自东昆仑造山带倾斜段都兰火山-侵入复合体的新数据，整合了锆石 UPb 测年、微量元素、磷灰石和锆石 Hf 同位素地球化学以及全岩地球化学，以研究火山-侵入连接并跟踪晶体熔融离析过程。Dulan 杂岩体由流纹岩、花岗斑岩和花岗闪长岩组成，均显示出一致的锆石 UPb 年龄、稀土元素 （REE） 模式和 εHf（t） 值，表明存在共享的岩浆来源。斜长石、碱长石和角闪石的晶状晶，以及前晶锆石和磷灰石，意味着花岗闪长岩和花岗斑岩具有累积亲和力。全岩和辅助矿物的成分变化表明，斜长石、磷灰石和锆石分馏对岩浆的演化有显著影响。我们提出了在 ∼ 2 Myr 长的岩浆储层系统中采用两阶段晶体偏析过程。在早期阶段，在 ∼33 公里深处，水液流入引发了晶体熔体离析，从残留的糊状物中形成了 Dulan 花岗闪长岩。在后期，镁铁质熔体和流体注入在 ∼12 km 深度的较浅储层中导致晶体熔体偏析，高二氧化硅岩浆产生流纹岩，而残余的糊状物固结成花岗斑岩。 我们的研究结果表明，火山-侵入式连接比单纯的成分等效性或互补性更复杂，需要通过辅助矿物和全岩地球化学进行多维分析。