This study aims to reveal the mineralogical characteristics of the carbonate and pelitic rocks in the Lower Triassic Cigli Group in the Uludere-Uzungecit (Sirnak) region from Southeast Anatolian Autochthone (SEAA). Cigli Group is represented by Yoncali Formation (dolomite-siltstone-shale with limestone intercalation), Uludere Formation (shale/shale with carbonate-clayey limestone intercalated with dolomite) and Uzungecit Formation (limestone with chert nodule-dolomitic limestone-shale) from bottom to top. In order of abundances of minerals obtained by XRD investigations as follows; Yoncali Formation contains carbonate (calcite, dolomite), feldspar, phyllosilicate (illite, chlorite) and goethite minerals, and Uludere Formation is made up of carbonate (calcite, dolomite), quartz, feldspar, phyllosilicate (illite, chlorite, mixed-layered chlorite-vermiculite/C-V, and very minor amount of kaolinite in only a sample) and hematite minerals. Uzungecit Formation has carbonate (dolomite, calcite), silica (quartz, opal-CT, moganite), phyllosilicate (chlorite, illite), and feldspar and hematite minerals. On the basis of illit Kubler Index values; Yoncali Formation reflects the degrees of anchizone; as for Uludere and Uzungecit formations, they have the degrees of anchizone-high diagenesis, respectively. Similarly, Chlorite Arkai Index (AI, degrees 2 theta) values indicate the grades of anchizone-diagenesis. Illites exhibit 2M(1) ve 2M(1) + 1M + 1M(d) polytypes and the values of b unit-cell distances show a composition close to ideal muscovite and low pressure conditions.