A prominent subduction-related magmatic arc hosting significant mineralization formed in SE Europe during the Late Cretaceous. Previous studies on major magmatic centers and ore deposits suggested that this belt formed through southwards retreat of a subducting Neotethys oceanic slab. However, the timing and the petrologic characteristics of magmatic products from the less mineralized eastern portions of this belt remain largely unknown. The complete lack of radiometric ages and limited geochemical characterization of this magmatism adds considerable uncertainty on existing large-scale geodynamic reconstructions focused on the Late Cretaceous magmatism in SE Europe. Here, we address this question by studying little known Cretaceous lavas and sub-volcanic bodies from the Eastern Balkan, Bulgaria. Major and trace element contents of these volumetrically limited rocks show a clear subduction signature. The most primitive rocks are high-Al basalts, which further differentiated into andesites and dacites via fractional crystallization in relatively small magma chambers. The mineral chemistry and assemblages constrain magmatic conditions prior to crystallization to pressures of 3–7 kb, temperatures of 900–1020 °C, water contents of ~4–7 wt% and high oxygen fugacities. Phenocryst features like reverse zonation of clinopyroxene and amphibole and sieve and patchy textures of plagioclase suggest magma mixing processes. Initial εHf values of Cretaceous zircons (+2 to −2) and inherited, mainly Variscan and older zircons (+3 to −11) provide clear evidence for assimilation of crustal lithologies by mantle-derived Late Cretaceous magmas. Amphibole phenocrysts from an andesite and a dacite give ⁴⁰Ar/³⁹Ar plateau ages of 94.67 ± 0.40 Ma and 94.56 ± 0.40 Ma, respectively. These dates are the oldest recorded in the entire Late Cretaceous magmatic belt and constrain the onset of the subduction magmatism to the later parts of the Cenomanian stage. Regional correlations based on these results reveal that processes of slab retreat were active also in the eastern part of the magmatic arc. Further, these results outline a clear temporal along-arc trend of progressively younger initiation of the arc magmatism from east to west.

在白垩纪晚期，在欧洲东南部形成的一个突出的与俯冲相关的岩浆弧承载着重要的矿化作用。先前对主要岩浆中心和矿床的研究表明，这条带是通过俯冲的新特提斯洋板块向南撤退形成的。然而，该带矿化程度较低的东部部分岩浆产物的时间和岩石学特征在很大程度上仍然未知。这种岩浆作用的辐射年龄完全缺乏和有限的地球化学特征增加了现有大规模地球动力学重建的不确定性，这些重建集中在欧洲东南部的晚白垩世岩浆作用上。在这里，我们通过研究保加利亚东部巴尔干地区鲜为人知的白垩纪熔岩和次火山体来解决这个问题。这些体积有限的岩石的主要和微量元素含量显示出明显的俯冲特征。最原始的岩石是高铝玄武岩，在相对较小的岩浆房中通过分步结晶进一步分化为安山岩和英安岩。矿物化学和组合将结晶前的岩浆条件限制在 3–7 kb 的压力、900–1020 °C 的温度、~4–7 wt% 的水含量和高氧逸度。斜长石和斜长石的筛状结构和斑片状纹理等斜长石和角闪石的反向分带等斑晶特征表明岩浆混合过程。白垩纪锆石的初始 εHf 值（+2 到 -2）和继承的，主要是瓦利斯坎和更老的锆石（+3 到 -11）为地幔来源的晚白垩世岩浆同化地壳岩性提供了明确的证据。⁴⁰ Ar/ ³⁹ Ar 平台年龄分别为 94.67 ± 0.40 Ma 和 94.56 ± 0.40 Ma。这些日期是整个晚白垩世岩浆带中记录的最古老的日期，并将俯冲岩浆作用的开始限制在 Cenomanian 阶段的后期。基于这些结果的区域对比表明，在岩浆弧东部，板块退缩过程也很活跃。此外，这些结果勾勒出从东到西弧岩浆作用逐渐年轻化的明显的时间沿弧趋势。