Sedimentary logs revision
- Created by: jbeaty1
- Created on: 05-11-19 17:59
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- Sedimentary Facies
- Hot Desert sequence
- Evaporites of a playa lake
- This is due to the high temperatures causing high rates of evaporation
- Sequence of evaporite minerals, least soluble are further out and more soluble are close to centre
- Wadi conglomerate
- High intensity rainfall = high energy to carry large fragments
- Rapid deposition
- Angular to sub- angular clasts
- Dunes
- Extensive aeolian sandstone dunes
- Move in direction of prevailing wind
- Preserved as cross bedding
- Evaporites of a playa lake
- Deltaic sequences
- Coarsen upwards
- From mudstones and siltstones to coarser sediment at delta front
- Sedimentary structues
- Inverse graded bedding
- Current ripples
- Rock Types
- Coal formed in terrestrial swamps
- Limestone represents normal marine conditions
- occurs at the start of a cyclothem
- Change in sea level
- Delta migration- prograding or retreating
- occurs at the start of a cyclothem
- Coarsen upwards
- Turbidite sequence
- Occur in deep marine envirionments
- Few sedimentary structures
- Examples of high energy currents reaching deep marine
- Commonly initiated by a turbidity current
- Sediment on continental slope becomes unstable
- Erosive base and deposition of conglomerate and sandstones
- Fluvial sequence
- Meandering river
- Similar to delta, but fines upwards
- Clays and silts are deposited onto flood plain
- Cross bedding represents deposition in bars
- Desiccation cracks show sub-aerial exposure to elements
- Arkose sandstones are common
- Braided river
- Banks of sand and gravel deposited in channel
- Channel deposits occupy the riverbed over time
- Braided river
- Braided river
- Banks of sand and gravel deposited in channel
- Channel deposits occupy the riverbed over time
- Meandering river
- Hot Desert sequence
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