A slab detachment and delamination model for the generation of Carboniferous high-potassium I-type magmatism in the Eastern Pontides, NE Turkey: The Köse composite pluton

摘要: Abstract The Hercynian Kose composite pluton (KCP) is located in the Eastern Pontides, Turkey, and consists of two units high-K calc-alkaline, primarily peraluminous granites: (i) internal body, (ii) external body. which was emplaced at 322–318 Ma (40Ar/39Ar ages on biotite hornblende, respectively), displays a wide compositional range (49–71 wt.% SiO2) contains several lithologies: hybrid equigranular rocks, microgranular magmatic enclaves, mafic dikes, porphyry dikes mylonites. 306.7 Ma age K-feldspar), exclusively monzogranite (> 71 wt.% SiO2). Field relationships, mineralogy, major- trace element geochemistry, initial Sr–Nd isotope values (ISr = 0.70821 to 0.71002, eNd(t) = −6.6 −8.0) show that body differentiated evolved by crystal fractionation magma mixing processes. end-members process were rock felsic rock. Mafic derived from relatively deep-seated (25–30 km) crustal storage reservoir, not directly mantle, underwent significant differentiation fractional crystallization contamination before mixing. In addition, these storages probably supplied additional heat necessary initiate melting. Some may have also been released radiogenic decay producing elements. Eventually, existing melting K-bearing meta-greywackes raised its emplacement level depth ~ 10–16 km. After partial crystallization, it sporadically intruded modified deeper reservoir generate rocks. rocks then elevated shallower normal faults during collapse orogen erosion. Mylonites later overprinted pseudotachylites are typically constrained regarded as markers this event. characterized significantly less limited (ISr = 0.70639 0. 70792, eNd(t) = −4.4 −6.5) than those lack documenting open system Fractional exclusive responsible for elemental within contain relative All involve mid-crustal (orthogneisses) their source, depths near lower crust. absence purely crustal-derived melts can be explained removal type material formation parental melt. This melt ascended around ~ 5–10 km cut regional metamorphic had previously due ongoing injected into cracks crystallized porphyries because there enough time entire magma. data presented here indicate late Early Carboniferous Late magmatism occurred collisional setting. Slab detachment subsequent delamination seem most plausible mechanisms generation calc-alkaline Turkey.