Nannofossil Distribution and Age of Kendeng Zone In Kalibeng River Section of Kedungringin, Plandaan Area, Jombang, East Java

Choiriah, Siti Umiyatun (Geological Engineering, Faculty of Mineral Technology UPN “Veteran” Yogyakarta)
Prasetyadi, Carolus (Geological Engineering, Faculty of Mineral Technology UPN “Veteran” Yogyakarta)
Kapid, Rubiyanto (Geological Engineering, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB))
Yudiantoro, Dwi Fitri (Geological Engineering, Faculty of Mineral Technology UPN “Veteran” Yogyakarta)

Indonesian Journal on Geoscience
Vol 7, No 1 (2020)

DOI:10.17014/ijog.7.1.15-24This study was carried out at Kalibeng River Section, in Kedungringin area, a site with lithology suitable for a nannoplankton research. Methods used in this research include performing a stratigraphical measurement section at the field, collecting thirty-two samples, and preparing the samples with the smear slide method using a polarizing microscope with 1000x magnification, and preparing several rock samples using SEM analysis. The analysis of nannofossil resulted in twelve genera and forty-three species. The identified genera are: Calcidiscus, Coccolithus, Ceratolithus, Discoaster, Gephyrocapsa, Helicosphaera, Pseudoemiliania, Reticulofenestra, Rhabdosphaera, Sphenolithus, Syracosphaera, and Umbilicosphaera. The presence of these genera indicates that Kalibeng River Section have abundant nannofossils and based on the nannofossil analysis, from older to younger, the studied stratigraphic sequence indicates a more detailed age determination as follows: the Marl Unit of Kalibeng is NN10-NN18 (Middle Miocene to Pliocene), Calcareous Sandstone Unit of Sonde is NN19-NN20 (Pliocene-Pleistocene), and Calcareous Claystone Unit of Sonde is NN20-NN21 (Pleistocene).