Stratigraphy and Foraminiferal Biostratigraphy of Sentolo Formation in Sedayu Area: Local Unconformity Identification in Early Pliocene

Akmaluddin Akmaluddin; Muhammad Virgiawan Agustin; Ma’ruf Kurniawan Adi

doi:10.22146/jag.48596

Stratigraphy and Foraminiferal Biostratigraphy of Sentolo Formation in Sedayu Area: Local Unconformity Identification in Early Pliocene

https://doi.org/10.22146/jag.48596

Akmaluddin Akmaluddin^(1*), Muhammad Virgiawan Agustin⁽²⁾, Ma’ruf Kurniawan Adi⁽³⁾

(1) Geological Engineering Departement, Universitas Gadjah Mada
(2) Geological Engineering Departement, Universitas Gadjah Mada
(3) Geological Engineering Departement, Universitas Gadjah Mada
(*) Corresponding Author

Abstract

The study area is located in Sedayu District, Bantul Regency, Special Region of Yogyakarta Province which belongs to the Sentolo Formation. This area is an interesting place to study because there are erosional boundaries that indicate an unconformity in the Sentolo Formation. In this study, stratigraphic measurements and sampling were carried out in the field, then the samples were prepared and analyzed for the content of planktic and benthic foraminifera fossil. The results of the analysis are the determination of biozonation, paleobathimetry, and identification of sedimentation rates and unconformity. From the data analysis, ware known that the Sentolo Formation in Sedayu area can be divided into three lithofacies, namely thickening upward calcareous sandstone – calcareous siltstone facies, channel calcareous sandstone – calcareous siltstone facies andthinning upward limestone facies. Based on the biostratigraphy analysis, can be divided into four biozonations, namely the PL1A, PL1B, PL1C, and PL2 zones which are included in the Early Pliocene age. There is an unconformity in the facies boundary of the channel calcareous sandstone – calcareous siltstone facies with thinning upward limestone facies, identified by the presence of an erosional boundary at that interval and also supported by sudden changes in paleobatimetry from Upper Bathyal to Middle Neritic. The sedimentation rate identified in this area has a value of 15.5 m / Ma which identified in the lower facies. The extrapolation results of age and sedimentation rates concluded that the unconformity occurred at 4.46–4.20 Ma, and eroded 4.03 m thick of sedimentary rocks

Keywords

Biostratigraphy , Local unconformity identification , Early Pliocene , Sentolo Formation.

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References

Armstrong, H., & Brasier, M. (2005) Microfossils, Blackwell Publishing, United Kingdom.

Berggren, W.A., Kent, D.V., Swisher, C.C., Aubry, M. (1995) A revised Cenozoic geochronology and chronostratigraphy. In: Berggren, W.A., Kent, D.V., Aubry, M.-P., Hardenbol, J. (Eds.), Geochronology Time Scales and Global Stratigraphic CorrelationSEMP Special Publication, vol. 54, pp. 129–212.

Blow, W.H. (1969) Late Middle Eocene to Recent Planktonik Foraminiferal Biostratigraphy. In Bronnimann P. and Renz, H.H. (eds.) 1st Conference on Planktonik Microfossils Proceedings (Geneva, 1967). E.J. Brill, Leiden, v. 1, h. 199–412, 43 gbr., 54 pl.

Bolli, H., M., Saunder, J. B., dan Nielsen, Pearch K. (1985) Plankton Stratigraphy. Cambridge University Press. Jones, R.W. (1994) Challenger Foraminifera. Oxford: Oxford University Press, 149 pp.

Komisi Sandi Stratigrafi Indonesia (1996) Sandi Stratigrafi Indonesia, Ikatan Ahli Geologi Indonesia, Jakarta.

Leckie, R. Mark, Farnham, C., Schmidt, M.G. (1993) Oligocene Planktonic Foraminifer Biostratigraphy of Hole 803D (Ontong Java Plateu) and Hole 628A (Little Bahama Bank), and Comparison with the Southerns High Latitudes, In Berger, W.H., Wise, S.W., Jr., Schlich, R., et al., Proc. ODP, ScII. Results, 130 (Pt. 2): College Station, TX (Ocean Drilling Program), 113–130.

Rahardjo, W., Sukandarrumidi, dan Rosidi, H.M.D. (1995) Peta Geologi Lembar Yogyakarta, Jawa, Edisi ke-2, Pusat Penelitian dan Pengembangan Geologi, Bandung.

Van Bemmelen, R.W. (1949) The Geology of Indonesia, Vol. I.A. General Geology. Martinus Nyhoff, The Hague.

Wade, B. S., Pearson, P. N., and Berggren, W. (2011) Review and Revision of Cenozoic Tropical Planktonic Foraminiferal Biostratigraphy and Calibration to the Geomagnetic Polarity and Astronomical Time Scale, Earth Science Riview 104.

DOI: https://doi.org/10.22146/jag.48596