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In these Lecture Slides, the Lecturer has discussed the following key points in his class of Stratigraphy : Mass Flows, Spectrum, Flow Types, Slow Intergranular, Frictional Sliding, Static Grain, Contacts, Coherent Mass, Minor Internal, Rotational
Typology: Slides
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Slow intergranular frictional sliding with quasi-static grain contacts
Coherent mass with minor internal deformation, translational (here) or rotational
SLUMP Coherent mass with considerable internal deformation (discrete, non- pervasive shear) Docsity.com
FLOW with PLASTIC behaviour Remoulded mass, non-turbulent, but possibly with transient large-scale turbulent churning and entrained turbidity current at upper boundary ( liquefied flow / debris flow )
FLOW with FLUIDAL behaviour Fully turbulent ( turbidity current )
Solitary grains or loose grain assemblages
erosive base normal grading with large clasts at base traction current structures
matrix-supported, mud- or sand-rich, subhorizontal fabric, some vertical clasts isolated “megaclasts” basal pseudolamination
clast-supported, sandy matrix, a(p) fabric inverse grading in basal shear zone wavy base with erosion in places
matrix-supported, sand/fine gravel matrix horizontal fabric no grading
tightly packed gravel with erosive base, weak normal grading a(p) & a(t) fabric
non-cohesive debris flow
clast-supported, sandy matrix, a(p) fabric inverse grading in basal shear zone wavy base with erosion in places
stream flow deposit
erosive base normal grading with large clasts at base traction current structures
non-cohesive debris flow
matrix-supported, sand/fine gravel matrix horizontal fabric no grading
cohesive (?) debris flow
matrix-supported, mud- or sand-rich, subhorizontal fabric, some vertical clasts isolated “megaclasts” basal pseudolamination
stream flow deposit
tightly packed gravel with erosive base, weak normal grading a(p) & a(t) fabric
normal grading to stratified sand near top (indicative of waning flow conditions) crude, thick, irregular cross-strata in gravel clast-supported texture crude imbrication channelised base, possibly with large flutes
turbulent “streamflood” deposit (hyperconcentrated flow?)
normal grading to stratified sand near top (indicative of waning flow conditions) crude, thick, irregular cross-strata in gravel clast-supported texture crude imbrication channelised base, possibly with large flutes
Independent of flow thickness
Proportional to flow thickness … but not necessarily linear : frictional strength viscous resistance dispersive pressure transient turbulence fluidisation
Nemec & Steel (1984) Docsity.com
New Red Sandstone fanglomerates
with cohesive strength
no cohesive strength
