BIOFACIES STUDY OF MIDDLE MIOCENE FORAMINIFERA CARBONATE ROCK OF THE PEGUNUNGAN SELATAN IN WONOSARI AREA, D.I. YOGYAKARTA

• Main Author: Yan Patriani, Emma
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/76374
• Institution: Institut Teknologi Bandung

The Middle Miocene limestone deposits of Southern Mountains, D.I. Yogyakarta consist of Wonosari and Punung Formations. The rocks contain organisms such as foraminifera planktonic, small benthic foraminifera, large benthic foraminifera, algae, corals and molluscs that needed specific ecological condition for growing and developing. The identification of foraminifera biofacies was carried out to create a model of carbonate rocks in the Southern Mountains. A total of 90 outcrop samples have been collected that represents various carbonate facies of the Southern Mountains. Based on lithologic and petrographic sequence analysis, the carbonate rocks can be grouped into (5) five facies belt correlated with the Wilson standard (1975). The content of foraminifera biofacies were characterized using multivariate analysis (cluster analysis and principal component analysis), indicator value for collecting taxa unique of each facies carbonate rocks. The results of study are as follows: (1) basin facies is characterized by planktonic foraminifera and Textulariina, (2) open sea shelf facies is characterized by Cycloclypeus spp., Amphistegina spp. and planktonic foraminifera (3) foreslope facies is characterized by Cycloclypeus spp., Amphistegina spp., Lepidocyclina spp. and planktonic foraminifera and also coral fragments, (4) Winnowed platform-edge facies is characterized by Amphistegina spp., Miogypsina spp., Cycloclypeus spp. and Textulariina and also rhodolith; (5) Open platform facies is characterized by Amphistegina spp., Lepidocyclina spp., small miliolina, Rotaliina and also green algae and molusc (bivalvia).