Sed Geo Final

relief

how dark the lines around the edges are

Cleavage

a preferred fracture orientation

Pleochroism

grain changes color when rotated under plane-polarized light

Birefringence

distinctive colors seen in anisotropic minerals under cross-polarized light

twinning

crystals in the same grain formed with opposite orientation of their crystal lattice

Quartz

Typically colorless in plane-polarized light, shades of gray in cross-polarized light, has low relief

Calcite in thin section

Two cleavage planes, high relief, pale green and pink birefringence

Easiest way to distinguish different types of feldspars

twinning

lithic grains, matrix, cement

Besides the different types of individual mineral grains in a sandstone, other constituents may include:

Laminar flow

low flow rates

Turbulent flow

high flow velocities

rolling

clasts move along the bottom of the fluid column and stay in contact with the bed

saltation

particles jump or bounce along the bed surface

Suspension

turbulence keeps the particles in the fluid column

bedload

particles being carried by rolling and saltation

suspended load

the sediment load being carried in the fluid column without interacting with the bed surface

Normal grading

Grain size decrease from the bottom to the top of a single bed

Reverse Grading

Increase in grain size upward within a single bed

Fining upward

pattern of overall smaller grain sized upward through a number of beds

coarsening upward

pattern of overall larger grain sizes upward through a number of beds

Bouma Sequence

associated with turbidity currents

Downstream

Ripples that form under unidirectional flow have asymmetric shapes and cross-lamination that dip

Current ripple produces

cross-lamination

straight-crested dune produces

planar cross-bedding

sinuous-crested dune produces

trough cross-bedding

plane bedding produces

planar lamination

interbedded

alternations of thin beds of different lithology

cross-stratification

any layering that is at an angle to the depositional horizon

primary current lineation

ridges on bedding planes parallel to flow direction

stoss

upstream side of a ripple

lee

downstream side of a ripple

wave base

the depth to which surface waves affect a water body is the

Wave ripples

symmetric

flood tides

Tidal currents which move water onshore

Ebb tides

Tidal currents which move water offshore

mud drapes

thin layer of mud on foresets of cross-stratified sand

reactivation surface

a minor erosion surface within cross-stratification reflecting current reversals

Tidal bundle

a cyclical variation of thickness in foreset laminae in cross-beds reflecting variations in flow strength

Herringbone cross stratification

bipolar cross-stratification produced by alternating directions of ripple migration

flaser bedding

isolated thin drapes of mud in a cross-laminated sand

till

all deposits directly deposited by ice

diamicton / diamictitie

deposits of poorly sorted material

meltout till

typically deposited at the front of a glacier

lodgement till

deposited at the base of a glacier

True

True or false: Cross-lamination is much less common in aeolian ripples versus water-lain ripples.

Grain Flow

Aeolian dunes do not migrate the same way as water-formed dunes. Sediment still migrates up the stoss side of the aeolian dune but instead of rolling down the lee side, it either blows off the top of the dune or the dune crest oversteepens and avalanching occurs in a process called __.

foreshore

region between mean low and mean high tide

shoreface

region below low tide and above fair weather wave base

offshore-transition

region between fair weather and storm wave base

offshore

region between storm wave base and the shelf break

global

Eustatic refers to (global / local)\___________ sea-level whereas relative refers to

local

relative refers to ___________ sea level

transgression

A rise in relative sea-level is called a

regression

whereas a fall in relative seal-level is called a

retrogradational

During a transgression, the shoreline shifts landward and the deepening upward succession of facies is called a(n) __ stacking pattern.

progradational

During a regression, the shoreline shifts basin-ward and the shallowing upward succession of facies is called a(n) __ stacking pattern.

progradation

The definition of a delta includes the building out of sediment into a lake or sea, a process known as ____.

shallowing-upward

Because a delta progrades over time, the stratigraphic succession produced has a(n) __ pattern.

delta plain,delta channel,distributary mouth bar,delta front, prodelta

Put the facies associations in order from bottom to top to represent a typical stratigraphic up-section succession that results from a prograding delta.

True

True or False: A delta represents progradation during relative sea level fall whereas an estuary records retrogradation during a relative sea level rise.

wave dominated

A bay-head delta, central lagoon, and beach barrier are features of this type of estuary.

fining- and deepening-upward

The stratigraphic record of a tide-dominated estuary is generally...

washover deposit

lobes of sand in the back-barrier emplaced by storms

tidal channel deposit

sandy deposits with an erosional base that cut through the barrier deposits

tide delta deposit

form on both the seaward and landward side of the barrier

foreshore

seaward-dipping laminae that are deposited in the (foreshore/backshore)

backshore

landward-dipping laminae that demarcate the (foreshore/backshore)

False

On a wave-dominated shoreline, the finest sediments are deposited along the shoreline (foreshore and proximal shoreface) whereas coarser-grained sediments are found in the seaward parts (distal shoreface and offshore-transition).

False

True or False: Beach deposits are generally texturally and compositionally immature sediments.

intertidal zone

This zone within a tide-dominated shoreline that lies between low and high tide and is subaerially exposed once or twice a day.

supratidal zone

This zone within a tide-dominated shoreline that lies above the high tide level and can be a salt-marsh or sabkha environment depending on the climate.

finer,coarser

In general, the grain size trend along tide-dominated shorelines is (finer/coarser)-grained in the upper, supratidal zone to (finer/coarser) in lower subtidal zone

tidal channels

Bi-directional cross-stratification, one of the higher velocity structures in this environment, is typically formed in the...

sand flats

flaser bedding

mixed flats

wavy bedding

mud flats

lenticular bedding

Upper shoreface

dominated by sand and affected by everyday waves

Lower shoreface (offshore transition)

characterized by HCS

Offshore

below storm wave base and dominated by mud deposition

True

True or False: HCS are not typically preserved in shoreface deposits (the region above fairweather wave base).

Tempestite

This storm deposit with a sharp erosional base overlain by planar laminated sandstone, HCS, wave-rippled sandstone, then mudstone is an example of a...

transgressive lag

This is the name for a thin layer of gravel that forms during sea level rise due to reworking of sediment by wave action.

depositional lobe

The region of the submarine fan that most often contains the most complete Bouma sequences is...

mud-rich

The largest submarine fan systems in the modern oceans are...

olistolith

large blocks of rock that avalanche down to the slope

spill-over sand

sediment reworked from the edge of the shelf as a turbidity current

pelagic muds

sediment that settles out of suspension

debris flow

remobilization of poorly-sorted sediment-rich mixture downslope

pelagic sediment

suspended sediment away from shorelines

calcareous ooze

consolidates to form a fine-grained mudstone

siliceous ooze

consolidates to form chert

hemipelagic

fine-grained sediment directly derived from a nearby continent

3000-4000m

The carbonate compensation depth (CCD) is around __ deep.

False

True or false: Between the depths that waves and tides act and the CCD, there are many paleowater-depth indicators that can be used to interpret ancient strata.

low

The primary requirement for the formation of carbonate platforms is an environment where clastic supply is _.

carbonate shelf

a platform attached to a continental landmass that is flat with a steep shelf/slope break

carbonate bank

isolated platform surrounded by deep water

carbonate atoll

a bank formed above a volcanic island

carbonate ramp

a platform with a gentle slope into deeper water and no sharp shelf/slope break

saltern

An area of hypersaline shallow water, such as a lagoon, that precipitates evaporite minerals is known as a __.