Batugamping berwarna merah yang tersebar secara setempat-setempat dan berasosiasi dengan batugamping berwarna putih hingga abuabu yang dijumpai di Daerah Ponjong, Kabupaten Gunungkidul, Daerah Istimewa Yogyakarta, termasuk dalam Formasi Wonosari-Punung. Batugamping tersebut perlu diteliti karakteristik mineralogi dan geokimianya, yang sangat diperlukan dalam memahami genesa batugamping di daerah tersebut. Pengamatan petrografi dan XRD pada batugamping merah menunjukkan hadirnya mineral kalsit, kuarsa, siderit, hematit, dan titanit. Analisis geokimia oksida mayor batugamping merah memperlihatkan tren pengkayaan senyawa SiO2, TiO2, Fe2O3 dan MnO yang diinterpretasikan berhubungan dengan kehadiran mineral-mineral titanit (CaTiSiO5), siderit (FeCO3), hematit (Fe2O3), dan diduga rodokrosit (MnCO3). Mineral-mineral tersebut mempunyai karakteristik warna coklat kekuningan, merah muda sampai merah sehingga dimungkinkan dapat memberikan warna merah pada batugamping. Ada tiga proses yang diinterpretasi berperan dalam genesa batugamping merah Ponjong yaitu pengaruh material terigenus yang mengandung oksida SiO 2 , Al 2 O 3 , Fe 2 O 3 , dan TiO2 saat pengendapan batugamping, proses diagenesis oleh air meterorik yang mengkayakan senyawa Fe2O3 dan proses bekerjanya larutan hidrotermal.

A geochemical study was carried out to determine the geochemical characteristics of limestone in Wonosari-Punung Formation, and to suggest its depositional conditions and the source of rare earth elements. The study was conducted at Ponjong Area, Gunungkidul Regency, Daerah Istimewa Yogyakarta, Indonesia. White limestone which contains more abundant calcite is characterized by the highest CaO concentration. Red limestone which is associated with impure minerals such as siderite, rodochrosite, hematite, and titanite is typified by depleted CaO but higher SiO 2 , Fe 2 O 3 , MnO, and TiO 2 concentrations. Grey limestone characterized by depleted CaO and higher MnO contents is considered to be influenced by the presence of impure minerals of manganite (Mn 2 O 3 .H 2 O) and/or pyrolusite (MnO 2). Depletion of Sr concentration in the coloured limestone indicates that the diagenetic process increases from the white limestone to the coloured limestone. The process possibly occurred post-deposition of the limestones. The limestones show positive Mn* values (2.46-2.95) and authigenic U values (0.89-3.38) that suggest an oxidative environment. The Ce/Ce* values (0.57-0.80), Eu/Eu* values (1.04-1.88), high Y/Ho ratio, and low La N /Yb N ratio are indications that the rare earth elements in the limestones were derived from terrigenous materials. The positive Eu anomaly and enrichment of Cr and Mn of the limestones are indications of hydrothermal fluid activity taking place in the studied area. Based on the geochemical characteristics of the Punung-Wonosari limestones, the depositional environment and the source of rare earth elements of the limestones were therefore influenced by a combination of hydrothermal fluid activity with small amount of terrigenous material input and post depositional diagenetic process.