Five thin (5–15 cm) and yellowish green tephra (K-bentonite) layers are exposed along two sections in the south of Akşehir (Konya, southern Turkey) within the Early Carboniferous (Mississippian) red dolomite-dolomitic limestone succession of the Sultandağ Unit in the central Tauride Belt. K-bentonites exhibit typical porphyritic texture with euhedral plagioclase phenocrysts replaced by fine-grained white K-micas and sparry dolomite crystals. The intensively sericitized volcanic matrix has vitrophyric texture and contains hydroxidized euhedral pyrite crystals. Illite is the only clay mineral in all K-bentonite samples. Non-clay minerals are dolomite, calcite, quartz, pyrite, rutile and zircon. Illites have sheet-like flakes (1–4 μm sizes) showing well-developed orientations and partly slaty cleavage. Illite Kübler index values (KI, Δ°2θ) of K-bentonites reflect high-grade diagenetic to anchizonal conditions indicating temperatures that reached up to 200 °C. Illite d₀₆₀ values (1.4990–1.5007 Å) corresponding to dioctahedral composition display differences in coexisting slates and shales of the same age. Illite polytypes are characterized by the association of 2M₁, 1M and 1M_d. The presence of 1M illites is indicative of a volcanic (tephra) origin. Immobile element compositions suggest that tephras have been derived from trachyandesitic volcanism. K-bentonites exhibit some differences from the coeval pelitic occurrences in the Hadim-Bozkır areas, S Turkey, and the Late Devonian-Early Carboniferous K-bentonites in Bartın and Zonguldak areas of the Istanbul-Zonguldak Terrane, NW Turkey. A geochemical evolution of the studied K-bentonites suggests that they were possibly originated from the Early Carboniferous (Mississippian) intra-continental back-arc magmatism at the northern margin of Gondwana-derived Tauride-Anatolide microplate.

在苏丹国的早期石炭纪（密西西比州）红色白云岩-白云岩灰岩岩层中，阿克谢希尔（土耳其南部，科尼亚）南部的两个部分暴露了五个薄层（5–15厘米）和淡黄色的绿色辉石（K-膨润土）层。单位位于陶瑞德中央带。K膨润土表现出典型的斑状质构，带有正板斜长石面隐晶石，被细颗粒的白色K-米加斯和斯帕里白云石晶体所取代。强烈浆化的火山岩基质具有玻璃质的质构，并含有水合氧化的黄铁矿黄铁矿晶体。伊利石是所有钾膨润土样品中唯一的粘土矿物。非粘土矿物是白云石，方解石，石英，黄铁矿，金红石和锆石。Illite的薄片状薄片（大小为1-4μm）显示出良好的取向，部分呈片状分裂。钾基膨润土的伊利石库伯勒指数值（KI，Δ°2θ）反映了从成岩到顺层的高级成岩条件，表明温度高达200°C。伊利石ð₀₆₀对应于共存石板和相同年龄的页岩双八面体组合物显示差的值（1.4990-1.5007）。伊利石多型体通过的2关联特征中号₁，1中号和1中号_d。1M的存在伊利石是火山爆发的标志。不可移动的元素组成表明，特弗拉斯是由trachyandesitic火山活动衍生而来的。钾膨润土与土耳其南部Hadim-Bozkır地区的中世纪古胶质岩以及在土耳其西北部伊斯坦布尔-宗古达克地貌的Bartın和Zonguldak地区晚泥盆世-早期石炭纪钾膨润土表现出一些差异。所研究的钾膨润土的地球化学演变表明，它们可能起源于冈瓦纳派生的牛磺酸-阿那托利德微板块北缘的早期石炭纪（密西西比州）陆内弧后岩浆作用。