A quarter of Kamchatka’s Late Quaternary (<50 ka) volcanic deposits is erupted in the back-arc along the Sredinny Range (SR). The eruptions are represented by several dozens of polygenetic volcanoes and hundreds of monogenetic volcanoes located along a SW-NE lineament in the western part of the peninsula. Previous studies explained the generation of magma by (1) fluid induced melting of the mantle due to the input of H₂O from the presently subducting slab, (2) decompression-induced melting of the mantle caused by upwelling of the asthenosphere, or (3) delamination and melting of the lower crust of the SR. We present new major and trace elements in olivine and major, trace and volatile (H₂O, Cl, F and S) data in quenched olivine-hosted melt inclusions (MI) from three Holocene monogenetic volcanoes that are located in the southern, central and northern volcanic zones of the SR. The reconstructed melts range from basalts to basaltic andesites of medium-K affinity and exhibit trace element signatures that are transitional between island arc magmas (IAM) and enriched mid-ocean ridge basalts (E-MORB). They have high H₂O concentrations (from ~ 1.5 to 2.5 wt.%) compared to MORB with similar Nb/Y ratios, which suggests that the H₂O played an essential role in their origin. The high H₂O/Cl (from ~ 50 to ~ 100) and Ba/Rb (from ~ 20 to ~ 50) ratios and low Cl/K₂O (from ~ 0.02 to ~ 0.04) and Cl/F (from ~ 0.2 to ~ 0.5) ratios in these melts indicate that the budget of volatile components was controlled by the breakdown of amphibole. The Fe/Mn ratios and Ni contents in olivine from the studied Holocene volcanoes suggest significant contributions of melts derived from a pyroxenitic source. We propose that the parental magmas of these volcanoes were generated by combined partial melting of a range of delaminating lower crustal lithologies with pyroxene and amphibole and the surrounding peridotites. Their melting was facilitated by the influx of H₂O that was released from amphibole breakdown at high pressures. The amount of magma that was erupted along the Sredinny Range during the Late Quaternary can be produced by delamination of at least 7 vol.% of its crust. The proposed mechanism of delamination-induced melting may be involved in magma generation in other back-arc settings with a thick crust, such as back-arc regions of the Andean-type convergent margins and some active intra-oceanic back-arcs.

堪察加半岛晚第四纪 (<50 ka) 火山沉积的四分之一在斯雷丁尼山脉 (SR) 的弧后喷发。火山爆发的代表是几十座多生火山和数百座位于半岛西部 SW-NE 沿线的单生火山。先前的研究解释了岩浆的产生是通过（1）由于来自当前俯冲板片的 H ₂ O输入导致地幔的流体诱导熔化，（2）由软流圈上升引起的减压诱导的地幔熔化，或（ 3) SR 下地壳的分层和熔融。我们在橄榄石和主要、微量和挥发性 (H ₂O、Cl、F 和 S) 数据来自位于 SR 南部、中部和北部火山区的三个全新世单生火山的淬火橄榄石熔体包裹体 (MI)。重建的熔体范围从玄武岩到中等 K 亲和力的玄武质安山岩，并显示出岛弧岩浆 (IAM) 和富集洋中脊玄武岩 (E-MORB) 之间过渡的微量元素特征。与具有相似 Nb/Y 比率的 MORB 相比，它们具有高 H ₂ O 浓度（从 ~ 1.5 到 2.5 wt.%），这表明 H ₂ O 在它们的起源中发挥了重要作用。高 H ₂ O/Cl（从 ~ 50 到 ~ 100）和 Ba/Rb（从 ~ 20 到 ~ 50）比率和低 Cl/K ₂这些熔体中的 O（从 ~ 0.02 到 ~ 0.04）和 Cl/F（从 ~ 0.2 到 ~ 0.5）比率表明挥发性成分的预算受闪石分解的控制。来自所研究的全新世火山的橄榄石中的 Fe/Mn 比和 Ni 含量表明来自辉石源的熔体的重要贡献。我们认为这些火山的母岩浆是由一系列分层的下地壳岩性与辉石和角闪石以及周围橄榄岩的部分熔融结合产生的。H ₂的流入促进了它们的熔化O 在高压下从闪石分解中释放出来。晚第四纪沿 Sredinny 山脉喷发的大量岩浆可以通过至少 7 vol.% 的地壳分层产生。所提出的分层诱导熔融机制可能与其他具有厚地壳的弧后环境中的岩浆生成有关，例如安第斯型会聚边缘的弧后区域和一些活动的大洋内弧后。