| Popis: |
This study contains Becirman Formation of Late Paleogene age outcropping Batman-Gercus and Mardin-Dargecit areas in the Southeast Anatolian Authouctonous of Arabian Plate. The unit is formed of red colored dolomitic shale-marl-sandstone and white-cream colored carbonate rocks (dolomite, dolomitic limestone) intercalations. According to whole-rock analyses results of X-ray diffraction (XRD), minerals are represented, respectively in abundance, dolomite, phyllosilicate (palygorskite, smectite, chlorite, vermiculite, illite, serpentine and mixed layered C-V), calcite, feldspar, quartz, hematite and goethite. Phyllosilicates determining on XRD clay fractions comprise mineral paragenesis with palygorskite + smectite or vermiculite in Gercus area and palygorskite + chlorite + vermiculite / C-V, and chlorite + illite + serpentine in Dargecit area. Palygorskite minerals (2-10 mm-fibres length) occurred after dolomites and matrix in the dolomitic marl and sandstones, respectively, on scanning electron microscope (SEM) studies. Other associated minerals as smectite and chlorite / C-V are observed as thin leaves. Major element geochemistry of palygorskite-rich clay fractions indicates that these minerals are rich in Mg-Al-Fe. Trace element quantities of palygorskites on normalized spider diagrams have enrichments and depletions, respectively, compared to chondrite and North America Shale Composites (NASC). SEM views, existence of serpantine, especially increase of Cr and Ni concentrations, which indicate that the source of Becirman Formation is serpentinized ophiolitic rocks of Upper Cretaceous age in north of the basin. On the other hand, palygorskites are formed from dolomites and matrix by mechanisms of diagenetic transformation and sedimentary neoformation, respectively. |
