Geochemical Characteristics of Limestone of Wonosari-Punung Formation, Gunungkidul Regency, Yogyakarta, Indonesia

Abstract

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.

Sediment Characteristics of Beachrock: A Baseline Investigation Based on Microbial Induced Carbonate Precipitation at Krakal-Sadranan Beach, Yogyakarta, Indonesia

“…All the samples exhibit negative cerium and positive yttrium anomalies. This is also in concordance with precipitation from sea-water [33][34][35].…”

“…Beachrock found in Indonesia consisted of calcium, magnesium, sodium, and phosphorus element. However, according to the ICP-AES data, the composition is not similar to those of limestones and/or other beachrock which typically consists of silica and carbonate [34,35]. Hence, some previous studies have suggested that bacterial metabolism is related to the precipitation of rocks [42,49] and that the end products lower the thermodynamic boundary for cement nucleation and increases the rates of the physicochemical processes involved [42].…”

Major, trace, rare earth element, and stable isotope analyses of the Triassic carbonates along the northeastern Arabian Plate margin: a key to understanding paleotectonics and paleoenvironment of the Avroman (Biston) limestone formation from Kurdistan region, northeastern Iraq

“…The above discussion suggests that Ce is partially associated with detrital inputs, along with the original seawater fractionation (Dwi Atmoko et al 2018). The negative correlation between ΣREE and Al 2 O 3, (Fig.…”