Sedimentary Structures Flashcards
Tabular/lenticular seds rock layer w/ distinguishing characteristics
Beds
layers less than 1 cm are
laminae
Bed Classification by > 100 cm
VT
Bed Classification by 30-100 cm
T
Bed Classification by 10-30 cm
M
Bed Classification by 3-10 cm
Th
Bed Classification by 1-3 cm
VTh
Laminae Classification by 30-100 mm
VT
Laminae Classification by 10-30 mm
T
Laminae Classification by 3-10 mm
M
Laminae Classification by 1-3 mm
Th
Laminae Classification by<1 mm
Vth
distinct discontinuity (erosional surface) between two similar beds (composition wise)
- Amalgamation surface
those with amalgamation surface
- Amalgamated Beds
- Bedding planes (BP) represent:
1) Plane of non-deposition, (2) abrupt change in deposition, (3) erosion surface
beds w/ internal layers parallel to bedding surfaces
- Planar Stratified:
groups of similar planar beds
- Bedsets
groups of different beds but genetically associated
Composite Bedsets
internal layers deposited at an angle to the bounding surface, sometimes referred to as set of cross-strata
- Cross-stratified
a succession of cross-stratus
- Coset
- Parallel laminae common in sts, causes include:
o (1) beach swash n backwash,
o (2) wind transpo,
o (3) steady flow currents in upper-flow regime,
o (4), upper & lower flow regime phases during turbidity current flow and;
o (5) sheet flow
oscillatory equiv of plane-bed transpo in upper & lower-flow regime
Sheet flow:
- Characterized by vertically gradual + distinct changes in grain size
Graded
Coarse to fine, bot to top
- Normal Grading