Ifan Prasetya, Zanuar (2015) KETERDAPATAN DOLOMIT PADA BATUGAMPING FORMASI BULU DI DESA JURANGJERU, DESA GANDU, KEC. BOGOREJO DAN DESA KAJAR, DESA TEGALDOWO, KEC. GUNEM PROPINSI JAWA TENGAH. Masters thesis, U.
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Abstract
Lokasi penelitian berada di sekitar Desa Kajar, Desa Tegaldowo, Kecamatan Gunem, Kabupaten Rembang dan Desa Jurangjero, Desa Gandu Kecamatan Bogorejo, Kabupaten Blora. Wilayah ini memiliki potensi sebagai bahan baku industri semen yaitu batugamping, sehingga perlu diketahui kualitasnya. Salah satu faktor yang menentukan kualitasnya yaitu kandungan unsur MgO atau dolomit. Dalam industri semen, kandungan unsur MgO pada batugamping mempunyai spesifikasi kurang dari 5%. Oleh karena itu, dengan mengetahui penyebaran dolomit diharapkan bisa memberikan penjelasan mengenai kualitasnya sehingga bisa sebagai bahan pertimbangan untuk melakukan proses produksi penambangan batugamping. Kondisi geomorfologi di daerah penelitian terdiri dari dua bentuk lahan yaitu bentuk lahan karst antiklin sinklin dan perbukitan karst zona sesar dengan pola pengaliran dendritik dan jenis sungai periodik. Terdiri dari Formasi Bulu yang tersusun oleh batugamping berlapis, bersisipan batupasir dan batulempung yang berumur Miosen Tengah dan Formasi Paciran yang tersusun oleh batugamping terumbu masif berumur Pliosen Awal-Plistosen, sehingga hubungan kedua Formasi tersebut merupakan ketidakselarasan. Struktur geologi yang dijumpai berupa kekar dengan arah umum baratdaya-timurlaut dan tenggara-baratlaut. Terdapat 6 sesar mendatar yang relatif berarah umum barat-timur, baratdaya-timurlaut, dan tenggarabaratlaut. Lipatan terdiri dari sinklin dengan arah umum tenggara-baratlaut dan baratdaya-timurlaut serta antiklin dengan arah umum tenggara-baratlaut. Conto batugamping permukaan dilakukan analisa kimia sebanyak 92 dengan hasil 48 conto mengandung MgO lebih dari 4,6%. Wilayah penyebaran dolomit di Desa Tegaldowo mempunyai luas 67,5 ha dengan rata-rata MgO 15,69%. Penyebaran disekitar Desa Jurangjeru mempunyai luas 36,7 ha dengan rata-rata MgO 17,77%. Selanjutnya di Desa Gandu mempunyai luas 12,9 ha dengan rata-rata MgO 16,26%. Terakhir di sekitar Desa Kajar mempunyai luas 12,8 ha dengan rata-rata MgO 19%. Berdasar pengamatan sayatan tipis diperoleh nama dolostone, dolomitic limestone, recrystallized limestone dan limestone. Proses terbentuknya dolomit pada daerah penelitian akibat adanya percampuran antara air laut dan air tawar (mixingzone) pada zona freatik. Apabila diaplikasikan berdasarkan arah percampuran air laut dan air tawar, maka penyebarannya cenderung merata dibagian kiri dan kanan serta bagian tengah hanya sedikit. Tahap dolomotisasi pada awalnya me-replace lime mud, kemudian merubah komposisi bioclast. Selanjutnya ukuran kristal dolomit menjadi lebih jelas, berukuran fine/medium yang mengisi pori ataupun di pinggir pori sebagai cement dan bisa juga mengelilingi bioclasts, tahap terakhir kristal dolomit akan mengisi kekar yang ada. Location of the study were around the village of Kajar, Tegaldowo Village, District Gunem, Rembang and Jurangjero village, sub-district village Gandu Bogorejo, Blora. This region has potential as an industrial raw material cement is limestone, so keep in mind the quality. One of the factors that determine the quality of that content element MgO or dolomite. In the cement industry, the content of MgO in the limestone elements have a specification of less than 5%. Therefore, to determine the spread of dolomite is expected to provide an explanation of its quality so that it can as consideration for limestone mining production process. Geomorphological conditions in the study area consists of two forms, namely land anticline syncline karst landforms and karst hills fault zone with dendritic drainage patterns and the type of periodic river. Consisting of Bulu Formation composed of layered limestone, sandstone and mudstone have an insert that Middle Miocene and Paciran Formation composed by old massive reef limestones Early Pliocene-Pleistocene, so that relations between the two formations is an unconformity. Geological structures found in the form of a stocky with a general direction southwest-northeast and southeast-northwest. There are 6 fault leveled relatively common east-west trending, southwestern-northeastern, northwestern and southeastern. Folds consists of a syncline with general direction southeast-northwest and southwest-northeast and anticline with the general direction southeast-northwest. Sample limestone surface as many as 92 chemical analysis with the results of 48 samples containing more than 4.6% MgO. Dolomite deployment region in the village has an area of 67.5 ha Tegaldowo with an average of 15.69% MgO. The spread around the village has an area of 36.7 ha Jurangjeru with an average of 17.77% MgO. Furthermore, in the village Gandu has an area of 12.9 ha with an average of 16.26% MgO. Kajar last around the village has an area of 12.8 ha with an average of 19% MgO. Based on the observation of thin section obtained the name of dolostone, dolomitic limestone, recrystallized limestone and limestone. The process of formation of dolomite in the area of research due to the mixture of seawater and freshwater (mixing-zone) in the phreatic zone. If the mixture is applied based on the direction of seawater and freshwater, then spread evenly on the left and tend to be right and the middle just a little. Dolomotisasi stage initially to replace the lime mud, and then change the composition bioclast. Furthermore, the size of crystalline dolomite becomes more evident, measuring fine/medium that fills the pores or at the edge of the pore as cement and can also surround bioclasts, the last stage of dolomite crystals will fill the existing stocky.
| Item Type: | Thesis (Masters) |
|---|---|
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Engineering Sciences |
| Depositing User: | Erny Azyanti |
| Date Deposited: | 19 May 2016 02:32 |
| Last Modified: | 19 May 2016 02:32 |
| URI: | http://eprints.upnyk.ac.id/id/eprint/1611 |
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