bab 2 (pendahuluan & aplikasi geofisika)
TRANSCRIPT
TUJUAN KULIAH :• Dapat menentukan jenis-jenis endapan mineral dan membedakan
satu dengan yang lainnya di lapangan.• Dapat menjelaskan pembentukan berbagai jenis endapan mineral .• Dapat menerapkan pengetahuan tentang endapan mineral sesuai
dengan bidang keilmuan masing-masing.
JADWAL KULIAH :• SELASA : 09.00 – 11.00 WIB; R. 9027• KAMIS : 11.00 – 12.00 WIB; R. 9017 (sesuai kebutuhan)
PRAKTIKUM (Minggu 3 – 4 Pebruari)
EKSKURSI (disarankan ikut)
PENILAIAN :• Absensi (5%, kehadiran minimal 75%)• UTS (30%)• UAS (30%)• Praktikum (30%)• Tugas & Kuis (5%)
REFERENSI :
USGS Regional Bouguer Gravity map. Source: X-Cal. The caption has the following bullet points: "Major NW Structure, Alignment of Deposits, Periodicity of Deposits,
and Major Deposits at Structural Intersections."
USGS Regional Airborne Magnetic Survey. Source: X-Cal. The caption has the following
bullet points: : "Alignment of Intrusions, Deposits Near Intrusions."
Rock/Mineral Magnetic Susceptibility
Rocks
Salt 0 – 0.001
Slate 0 – 0.002
Limestone 0.00001 – 0.0001
Granulite 0.0001 – 0.05
Rhyolite 0.00025 – 0.001
Greenstone 0.0005 – 0.001
Basalt 0.001 – 0.1
Gabbro 0.001 – 0.1
Dolerite 0.01 – 0.15
Minerals
Pyrite 0.0001 – 0.005
Hematite 0.001 – 0.0001
Pyrrhotite 0.001 – 1.0
Chromite 0.0075 – 1.5
Magnetite 0.1 – 20.0
Magnetic susceptibilities of selected rocks and minerals.
Rock Type Specific Gravity Mineral Specific Gravity
Coal 1.2 – 1.5 Sphalerite 3.8 – 4.2
Chalk 1.9 – 2.1 Chalcopyrite 4.1 – 4.3
Salt 2.1 – 2.4 Pyrrhotite 4.4 – 4.7
Serpentinite
2.5 – 2.6 Chromite 4.5 – 4.8
Granite 2.5 – 2.7 Pyrite 4.9 – 5.2
Quartzite 2.6 – 2.7 Hematite 5.0 – 5.2
Limestone 2.6 – 2.7 Magnetite 5.1 – 5.3
Gneiss 2.65 – 2.75 Galena 7.3 – 7.7
Basalt 2.7 – 3.1
Gabbro 2.7 – 3.3
Peridotite 3.1 – 3.4
Specific gravity values for selected common rocks and minerals
Gravity anomaly created by dense subsurface rocks.
Common Rocks/Materials
Resistivity (ohm meters)
Ore Minerals Resistivity(ohm meters)
Clay 1 – 100 Pyrrhotite 0.001 – 0.01
Graphitic Schist 10 – 500 Galena 0.001 – 100
Topsoil 50 – 100 Cassiterite 0.001 – 10,000
Gravel 100 – 600 Chalcopyrite 0.005 – 0.1
Weathered Bedrock 100 – 1000 Pyrite 0.01 – 100
Gabbro 100 – 500,000 Magnetite 0.01 – 1,000
Sandstone 200 – 8,000 Hematite 0.01 – 1,000,000
Granite 200 – 100,000 Sphalerite 1000 – 1,000,000
Basalt 200 – 100,000
Limestone 500 – 10,000
Slate 500 – 500,000
Quartzite 500 – 800,000
Greenstone 500 – 200,000
Resistivity of common rocks and minerals.
Current flow and natural self potential field developed around a sulfide ore body (from Dobrin, 1976).