Akademik Veri Yönetim Sistemi
12h International Multidisciplinary Scientific Geoconference (SGEM), Albena, Bulgaristan, 17 - 23 Haziran 2012, ss.233-240
Peperites are recognised as a mixture of magma and sediment, which is generated by an interaction of partly emergent domes and lava flows with unconsolidated sediments. They commonly occur in back-arc and rift settings where progressive subsidence of basins occurs contemporaneously with magmatism. This presented research deals with peperites formed along the ephemeral lacustrine sediments and the overlying smallvolume ultrapotassic lava flows in western Turkey. Ultrapotassic rocks occur as domes, dykes and lava flows and include peperitic basal contact zones. The peperitic contact zone with lava flows is defined by up-to-a metre thick layer of magma and sediment mixture. Magma clasts display fluidal and blocky morphologies with variable sizes ranging from few mm to a few decimetres. Fluidal clasts predominate with respect to blocky varieties. They were locally in-situ fragmented into blocky clasts that form a typical jig-saw texture. Blocky clasts are variably shaped and include digitate margins. Tapered clasts also occur along foliation planes of lava flows. Peperitic textures related to ultrapotassic lava flows closely resemble those generated by olivine basalt flows. Clast morphologies suggest a progressive fragmentation due to decreasing temperature along with increasing viscosity during peperite formation. Sediment fluidisation and low viscosity are presumed to be major controlling factors for fluidal clast generation and non-explosive emplacement. Common occurrences of peperite-bearing volcanic edifices in western Turkey suggest that magmatism developed within a progressively subsiding basin, probably corresponding to rift or back-arc extensional/ transtensional environment.