Early Cenozoic magmatism in the eastern Sakarya Zone (NE Turkey) provides an important constraint on the regional tectono-magmatic evolution of the region. Early Eocene syn-collisional adakitic rocks are observed as small stocks with outcropping areas commonly less than 10 km². This study presents petrography, whole-rock geochemistry and Sr-Nd-Pb isotope data, as well as in-situ ⁴⁰Ar/³⁹Ar age constraints on one of these adakitic andesites in the Altınpınar area of Gümüşhane, and discusses source region, petrological processes and geodynamic setting prevailed during their genesis. Andesites commonly show microlitic porphyric and vitrophyric porphyric textures, and include significant amounts of mafic microgranular enclaves (MMEs). Plagioclase, hornblende, Fe-Ti oxides and minor pyroxene are the main mineral phases. In-situ ⁴⁰Ar-³⁹Ar amphibole dating constrains the cooling age of andesites into a time span from 52.8 ± 1.3–48.8 ± 1.9 Ma. Andesites are medium to high-K calc-alkaline and display most of the signatures typical of those of the adakites. They are characterized by moderate MgO (1.7–4.1 wt%), low Y (9−14 ppm), Yb (0.9–1.5 ppm), and HREE and high Sr (325−964 ppm) contents, and high Sr/Y (36–76) ratios. ⁸⁷Sr/⁸⁶Sr_(t) (0.704948−0.705100) and ¹⁴³Nd/¹⁴⁴Nd_(t) (0.512588−0.512628) ratios are in the isotopic range of the adakites. All these geochemical and isotopic data suggest that the parental magma of adakitic andesites has been produced by partial melting of oceanic basalts under amphibole-eclogite facies conditions during the breakoff of the northern Neotethyan oceanic slab.

东部萨卡里亚带（土耳其东北部）的早新生代岩浆活动对该地区的区域构造岩浆演化提供了重要的制约。早始新世同碰撞埃达克质岩石被观察为小型种群，露头面积通常小于 10 km ²。本研究提供了岩石学、全岩地球化学和 Sr-Nd-Pb 同位素数据，以及原位⁴⁰ Ar/ ³⁹Gümüşhane 的 Altınpınar 地区这些埃达克质安山岩之一的年龄限制，并讨论了源区、岩石学过程和在其成因期间盛行的地球动力学环境。安山岩通常显示出微晶斑状和玻璃状斑状结构，并包括大量的镁铁质微粒飞地 (​​MME)。斜长石、角闪石、铁钛氧化物和微量辉石是主要的矿物相。原位⁴⁰ Ar- ³⁹Ar角闪石测年将安山岩的冷却年龄限制在52.8 ± 1.3–48.8 ± 1.9 Ma的时间跨度内。安山岩是中到高 K 钙碱性，显示出埃达克岩的大部分典型特征。它们的特点是中等 MgO (1.7-4.1 wt%)、低 Y (9-14 ppm)、Yb (0.9-1.5 ppm)、HREE 和高 Sr (325-964 ppm) 含量，以及高 Sr/Y ( 36–76) 比率。⁸⁷ Sr/ ⁸⁶ Sr _{( t )} (0.704948−0.705100) 和¹⁴³ Nd/ ¹⁴⁴ Nd _{( t )}(0.512588−0.512628) 比率在埃达克岩的同位素范围内。所有这些地球化学和同位素数据表明，埃达克安山岩的母岩浆是在新特提斯大洋板块北部断裂期间，在角闪岩-榴辉岩相条件下，大洋玄武岩部分熔融产生的。