Sedimentary Geology Geos 240 – Chapter 2 Collecting the Data Part 2 – Regional Geophysical Data Dr. Tark Hamilton Camosun College

Collecting the Data Stratigraphic Sections from Surface Outcrops Stratigraphic Sections from Surface Outcrops Petrophysical logging of boreholes Petrophysical logging of boreholes Well cuttings and cores Well cuttings and cores Regional Geophysics (Seismic, Gravity, Magnetics, Electro-Magnetics, Ground Penetrating Radar) Regional Geophysics (Seismic, Gravity, Magnetics, Electro-Magnetics, Ground Penetrating Radar) Labwork on sediments, rocks, fossils, fluids Labwork on sediments, rocks, fossils, fluids Computer/Office: Mapping, Interpretation & Modelling Computer/Office: Mapping, Interpretation & Modelling

Multi-Channel Reflection Seismic Sound source: explosive, vibroseis Sound source: explosive, vibroseis Geophone arrays ~21 per group to enhance S/n Geophone arrays ~21 per group to enhance S/n

Vibroseis Crews: Source Trucks

Seismic Sections need Well Ties Time  Depth conversion & marker beds Time  Depth conversion & marker beds

Contrasts between Seismic Facies Deep Marine BasinRiver Channels

Seismic versus Log Scales! Seismic = Regional, Logs = Local features Seismic = Regional, Logs = Local features

Seismic Section NW Africa (Morocco) Rifting of Pangea ~205 Ma Triassic/Lower Jurassic through Cretaceous Rifting of Pangea ~205 Ma Triassic/Lower Jurassic through Cretaceous Drift phase Tertiary, draping of older inactive structures Drift phase Tertiary, draping of older inactive structures

3D-Seismic for detailed areas Generate structure volumes, cross sections & subsurface maps Generate structure volumes, cross sections & subsurface maps

GPR – Ground Penetrating Radar Radar Frequency electromagnetic pulses Radar Frequency electromagnetic pulses Reflect off of Water Table Reflect off of Water Table Density contrasts, buried walls, graves, channels, vaults, subways! Density contrasts, buried walls, graves, channels, vaults, subways!

Core Strip Log & GPR Section: Alaska Nested channels, migrating bars Nested channels, migrating bars Gas sands on North Slope, also for placers, aquifers Gas sands on North Slope, also for placers, aquifers

Offshore Rigs & Drilling

THIS COVERS MOST CONVENTIONAL SEDIMENTARY GEOLOGY FOR RESOURCE EXPLORATION Mining Exploration, Environmental, Geotechnical, Aquifer, Academic & Archeological studies all do similar things but with smaller tools, areas of interest and way smaller budgets! Mining Exploration, Environmental, Geotechnical, Aquifer, Academic & Archeological studies all do similar things but with smaller tools, areas of interest and way smaller budgets!