Analysis of Microfacies and Depositional Environment of Limestone in Yosonegoro Area, Gorontalo Province, Indonesia

Abstract

The research location is the northern part of the Basin of Limboto Lake; the focus of the research is the limestone outcrop with 24 meter thickness in Yosonegoro area. The purpose of the study is to find out facies, standard microfacies and depositional environment on Limboto limestone. The research method carried out consisted of three methods namely the measured section, petrographic analysis and biostratigraphy analysis. The limestone facies in the Yosonegoro area consist of two facies. Then, based on sedimentary structure, composition, color, precipitation texture, terrestrial origin components and the organism content, the two facies can divided into three different microfacies. Paleobathymetry shows a deepening from the middle shelf-upper slope to the upper slopelower slope due to the sea level rise. Compilation of standard microfacies and paleobathymetry types shows changes in depositional environment from the slope environment to the toe of slope environment. The result of this study will be led researchers to propose the name of the new formation, which is the Limboto Limestone Formation according to specific location and characteristics from the previous formation name of the Clastic Limestone Formation.

Microfacies and Depositional Environment of Tertiary Limestone, Gorontalo Province, Indonesia

“…Limestone research in the Yosonegoro area produces two facies and microfacies, namely coraline rudstone facies and wackestone-packestone intercession facies with a slope to toe of slope depositional environment [10]. Limestone research in the north of Lake Limboto is carried out due to a lack of research data on Gorontalo limestone.…”

“…The research method consists of two stages. The first stage is doing a measured section (MS) using a 1.5 meter interval jacob's staff systematically from the oldest to the youngest rocks [10,11,12,13]. This method is fundamental to know the facies in the study site, including measuring the exact thickness of the facies and taking appropriate samples for petrographic analysis.…”

Analisis Lingkungan Purba Batugamping Daerah Limboto Barat Kabupaten Gorontalo

“…Berdasarkan penelitian terakhir yang dilakukan terdapat beberapa jenis dan fasies pengendapan batugamping. Beberapa fasies batugamping yakni fasies coralline rudstone, perulangan mudstone-packstone, fasies, sandy micrite dan sandy allochem limestone [4,5,6,7].…”

“…Bukti pengaruh tektonik pengangkatan di utara Cekungan Limboto yang saat ini tersingkap di permukaan dengan kecepatan pengangkatan 0,0699-0,0724 mm/tahun [3].Berdasarkan penelitian terakhir yang dilakukan terdapat beberapa jenis dan fasies pengendapan batugamping. Beberapa fasies batugamping yakni fasies coralline rudstone, perulangan mudstone-packstone, fasies, sandy micrite dan sandy allochem limestone [4,5,6,7].Penelitian ini sangat menarik untuk melengkapi penelitian sebelumnya mengenai batugamping dari segi komposisi fosil foraminifera. Penelitian mengenai paleobatimetri batugamping di selatan Danau Limboto pada zona neritik tengah-neritik luar [8,9].Umur batugamping di sekitar Danau Limboto berdasarkan penelitian terakhir yakni Miosen Akhir-Pliosen Awal [10] sedangkan penelitian sebelumnya berumur Pliosen-Pleistosen [11].…”

Erosion Hazard Analysis in the Limboto Lake Catchement Area, Gorontalo Province, Indonesia

“…There are three limestone microfacies in the slope to toe of slope depositional environment. While the rate of uplift limestone 0.0669-0.0724 mm/year [5,6].…”