Investigation of mineralogical and geochemical properties of sedimentary units in Kale basin (Denizli)

Kale Basin (Denizli) is a northeast-southwest trending basin filled with shallow marine sediments. While there are metamorphic basement rocks which belong mostly to Menderes massive to the west of the basin, there are ophiolites which belong to Lycia nappes as well as old Mesozoic limestones in the eastern and southern parts of the basin. The sediment layers which fill Kale Basin begin with coarse clastic sediments accompanied by pebbles that reflect a shallow shoreline environment at the bottom and as goes further through upper layers, it contains sandstones-mudstones and claystone which belong to a neritic environment. In the mudstones and claystone located in the upper parts of the sedimentary sequence, there are widespread leaf and charred plant remains as well as coal seams with a thickness of 5-10 cm especially in road cuts. Six coal exploration drillholes in the study area were made by Turkish Coal Enterprise. The depth of these boreholes varies between 426 m and 780 m. In the north part of the study area, 40-45 cm thick coal veins were cut at different levels within mudstone and claystone in the cores. The coal has a rank of lignite which is blackish and shiny in appearance. In other drillholes, coal veins 1- 3 cm thick have been observed in the levels of calcareous mudstone and claystone layers. This reflects that the layers of coal do not thicken laterally in the Oligocene succession and are graded to fine-grained deltaic sediments. When the cores were correlated, it was determined that the basin was shallower, the energy was lower and the organic matter content was rich in the north of the study area. The sudden deepening of the basin towards the south must be related to growth fault within the basin. The minerals of dolomite, calcite, feldspar, quartz and clay have been determined with XRD studies. Smectite, illite and kaolinite have been identified as clay minerals. Most of the dolomites in the basin were found to be ideal dolomites. Heavy rare earth elements show enrichment according to light rare earth elements. A similar NTE distribution of clay and carbonate samples indicates the same origin. According to Th / Co-La / Sc diagram, the samples fall to the acidic / fesic origin rock area.