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An Introduction to Geology. Sedimentary Rocks. Back to the Rock Cycle. Sedimentary processes. 1. Weathering 2. Transportation 3. Deposition 4. Lithification. OF. A. Existing rocks B. Biological materials C. Chemical precipitates. Sedimentary processes. Common sedimentary minerals.
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An Introduction to Geology Sedimentary Rocks
Sedimentary processes 1. Weathering 2. Transportation 3. Deposition 4. Lithification OF A. Existing rocks B. Biological materials C. Chemical precipitates
Common sedimentary minerals Quartz Feldspars Micas Calcite
Hand specimens First impressions?
Weathering Physical / Mechanical
Weathering Chemical / Biological
Transport mechanisms Rivers = fluvial Seas = marine Mississippi delta
AEOLIAN (wind) Can only transport small grains GLACIAL (ice) Huge volumes of sediment Transport mechanisms
Transportation Proximity + velocity = grain size
Transport time = maturity Textural maturity:
Transport time = maturity Mineralogical maturity:
Deposition Transportation into basins
Lithification Deposition (+ deposition + deposition) = burial Burial = compaction + cementation
Compaction Stylolites in chalk
Cementation • Mineral precipitation into pore spaces: • e.g. calcite, quartz, haematite
Hand specimens Second impressions?
Sedimentary rocks Particle size, shape and composition
Sedimentary rocks Particle size, shape and composition
Sedimentary rocks Particle size, shape and composition
Sedimentary rocks Particle size, shape and composition
Claystone Bituminous shales, Saltwick Nab, near Whtby
Sedimentary rock types 1. Clastic (or detrital)
Sedimentary rock types 1. Clastic (or detrital)
Sedimentary rock types 2. Biogenic (or organic)
Sedimentary rock types 2. Biogenic (or organic)
Sedimentary rock types 3. Chemical (precipitates)
Hand specimens What sedimentary rock type is your specimen?
Sedimentary structures Bedding
Sedimentary structures Cross-bedding
Sedimentary structures Cross-bedding
Sedimentary structures Ripple marks
Sedimentary structures Mud cracks
Sedimentary structures Shell beds
Sedimentary structures Trace fossils
Metamorphic Rocks Next week Under Pressure: