Lapisan condensed section pada batulempung gampingan Nanggulan, Pegunungan Kulonprogo, DIY

  • siti nuraini
Keywords: lapisan condensed section, Formasi Nanggulan, mineral glaukonit, genanglaut, batulempung gampingan

Abstract

Condensed section (cs) is defined as later stage of transgressive cycle which situated to the uppermost transgressive layer before reaching regressive phase of highstand systems tract (HST). This layer sometimes embraces to mfs (maximum flooding surface) as indicator of deepening depositional environment (Vail et all., 1984; Loutit et all., 1988). One of condensed section character is displayed by abundant glauconite minerals ((K, Na) (Fe3+, Al, Mg)2 (Si, Al)4O10 (OH)2) within fine grained lithology together with organic matters. These cs layer preserved in an oxidizing environment due to slow sedimentation process. In fact, within calcareous claystone of Nanggulan Formation is found accumulation of authigenic glauconite mineral. The purpose of this study to investigate condensed section (cs) character by microscopic observation of thin sections from Songgo and Watupuru of Nanggulan’s lithology.  Basically, glauconite mineral shows spherical or ovoid shape, green color, dull or earthy luster, embedded to calcareous claystone and also filled larger benthonic foraminifera tests. Glauconite only encountered to the fine grain rocks (calcareous claystone) however none to the underlying or upperlying of cs layer itself in Nanggulan Formation (such as sandstone, conglomeratic sandstone or siltstone). If it presents there, very few and indicating a reworking process of altered clay and ferroan oxidic minerals. Condensed section in Nanggulan Formation merges with fossil layer of Nummulites djogyakartae (Mark, 1956) which is interpreted to be a key indicator of post transgressive event in depth approximately 20- 60 m (boundary of inner neritic to middle neritic). In other word, transgressive phase had ever happened during Nanggulan age (Middle Eocene) which caused a decreasing clastic sediment supply to the basin.

References

Astuti, B.S., Humantoro, R., Hidayat, M., Kusuma, H.D., 2016, Analisis struktur geologi jalur Kali Watupuru dan Sungai Songgo daerah Degan Kulon Progo, dan implikasinya terhadap penyebaran batupasir kuarsa Formasi Nanggulan yang berpotensi sebagai reservoir, Proceeding Teknik Geologi, Universitas Padjadjaran, Bandung.

Huggett, J.M., 2013, Minerals: glauconites and green clays, Elsevier Inc.

Jorry, S.J., Dvaud, E., 2003, Depositional facies and sequence stratigraphy of reservoir Nummulite bodies in Central Tunisia (El Garia Formation, Upper Ypresian), result of a field analogue study from the Kesra Platey, AAPG Conference, Barcelona, 21-24, 2003.

Loutit, T.S., Handerbol, J. Vail, P.R., and Baum, G.R., 1988, Condensed sections: the key to age determination and correlation of continental margin sequences in: Sea-level changes- an integrated approach, SEPM Special Publication no.42

Marks, P., 1957, Stratigraphy Lexicon of Indonesia, Publikasi Keilmuan np. 31, Seri Geologi, Pusat Jawatan Geologi
Bandung.

Nuraini, S., 2017, Geometri perlapisan batupasir konglomeratan sebagai sisipan pada Formasi Nanggulan di Kali
Watupuru dan Kali Songgo, Pegunungan Kulon Progo, Yogyakarta, Kurvatex Journal, STTNAS, v.2/ 2 (November).

Pandita, H., Pambudi, S., Winarti, 2006, Kajian biostratigrafi dan fasies Formasi Sentolo di daerah Guluhrejo dan Ngaran Kabupaten Bantul untuk mengidentifikasi keberadaan Sesar Progo, Proceeding Teknik Geologi, Universitas Padjadjaran, Bandung.

Pettijohn, F.J., 1975, Sedimentary Rock, Harper and Row, 628.

Rahardjo, W., Sukandarrumidi, Rosidi, H.M.D,1995, Peta Geologi Yogyakarta, Jawa, skala 1;100,000, Pusat
Penelitian dan Pengembangan Geologi, Bandung.

Van Bemmelen, R.W., 1949, The Geology of Indonesia,1A, The Hague, Martinus Nijhoff, 732pp.

Vail, Peter; Rick, Sarg, 1987, Introduction to Seismic Stratigraphy. Tulsa: AAPG Films.

Wagoner, J. C., Van, Mitchum, Jr., R. M.., Posamentier H. W., dan Vail, P. R., 1987, Key Definitions of sequence Stratigraphy, AAPG Studies in Geology #27, volume 1: Atlas of Seismic Stratigraphy, edited by A. W. Bally, Pages 11-14.

Wentworth, C.K., 1922, A Scale of Grade and Class Terms for Clastic Sediments, The Journal of Geology 30, 377-392.
Published
2020-10-28
How to Cite
nuraini, siti (2020) “Lapisan condensed section pada batulempung gampingan Nanggulan, Pegunungan Kulonprogo, DIY”, ReTII, pp. 272-279. Available at: //journal.itny.ac.id/index.php/ReTII/article/view/2070 (Accessed: 28March2024).