STRATIGRAPHY AND SEDIMENTATION (SHALLOW MARINE) Flashcards

1
Q

Weak grains of sediments composed of Feldspar and Lithic Fragments

A

Labile Minerals and Grains

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2
Q

An authigenic material considered to be a reliable indicator of Shallow Marine Conditions

A

Glauconite

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3
Q

Greensands are shallow marine deposits rich in glauconite that are particularly common in what strata and what area of the world?

A

Northern Hemisphere, Cretaceous Strata

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4
Q

This is most intense in Sandy Shallow Marine Enviroment

A

Bioturbation

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5
Q

How much of the modern shelves are storm dominated?

A

80% Majority

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6
Q

How much of the modern shelves are Tide Dominated

A

17%

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7
Q

Shelves that are generally narrow and lie adjacent to strong GEOSTROPHIC Currents in which SANDWAVES and SAND RIBBONS form on them which make them similar to tidal shelves but the driving origin is not tidal

A

Ocean Current Dominated (3%)

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8
Q

Sea Level Rise for the past 10000yrs

A

Holocene Trangression

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9
Q

Shallow marine sedimanetatio is domiated by what type of deposits?

A

Terrigenous clastics

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10
Q

Shallow seas that are not supplied by much terrigenous materials are said to be areas of

A

Carbonate Sedimentation

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11
Q

What about areas that are cold and are not supplied much by terrigenous materials?

A

They are STARVED

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12
Q

Textural and compositional characteristics of Shallow Marine Sands

A

Compositionally and Texturally mature except in polat areas

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13
Q

What are the other distinctive characteristics of Shallow Marine deposits?

A

Diverse shells and skeletons presered in mudrocks and bicolastic fragments in sands

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14
Q

What kind of organisms dominate shallow marine?

A

Benthic

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15
Q

Why are primary sed structures not always preserved in Shallow Marine?

A

Because of High rates of Bioturbation

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16
Q

Type of Shallow Marine Clastic Environments

A

Storm Dominated
Tide Dominated
Ocean Current Dominated

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17
Q

Facies or parts of a Storm Dominated shallow Clastic Seas

A

1) Shoreface
2) Offshore Transitio
3) Offshore

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18
Q

These are the SHALLOWER PARTS of the Shelf and epicontinental sea and within the DEPTH ZONE FOR WAVE ACTION

A

Shoreface

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19
Q

Characteristics of Sand Deposits in Shorface

A

Wave Ripple Cross lamination
Horizontal Lamination
Flaser Beds(MinS)

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20
Q

Another common feature in Shoreface zone formed by Glows generated by EDDY Currents related to storms and/or wave-driven long shore drift

A

Sandy Ridges

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21
Q

Zone located between the Fairweather wave base and storm wave base

A

Offshore transition zone

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22
Q

Sedimentary structure that is thought ot be characteristics of STORM CONDITIONS on a SHELF

A

Hummocky Cross Stratification

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23
Q

Convex upward (Crests) that dip in all direction at agles 10-20 deg

A

Hummocks

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24
Q

Areas in between hummocks

A

Swales

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25
Q

Where concave layers are preserved it is said to be

A

Swaley Cross Stratification

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26
Q

What Forms HCS and SCS?

A

Combined flow of Strong Storm Current and oscillatory motion of waves

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27
Q

What are the limiations of HCS and SCS?

A

Formed only on fine to meium grained sand deposited in offshore transition

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28
Q

Characteristics of a idealized tempestite?

A

(B-T) NORMALLY GRADED!!!
1. Sharp Erosive Base
2. Structureless Coarse Sand and/or gravel
(First two layers represent scouring and initial deposition)
3. Hummocky-Swaley Cross Stratification in finer sands (Waning of Storm)
4. Overlain by Fine sand and silts with horizontal wave ripple lamination (Decrease in oscillation)
5 Top mud laminations

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29
Q

Characteritiscs of Offshore Zone?

A

Predominantly mud deposits (w/ Sand only in case of extraordinary storms)

Grey colored because of anoxic environment which allows preservation of organic matter within mud

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30
Q

Charactersitics of a Storm dominated Shallow Marine Envronment?

A
  1. Foreshore Beach Deposit of Stratified Sands
  2. Shoreface
    Sandy deposits with symmetric wave ripple lamination, horizontal stratification which may be destroyed by Bioturbation
    2.Offshore Transition Zone
    Tempestites (Scoured Base, Corase sand and gravel, HCS and SCS in finer sands, Fine sands and silts with wave ripple lamination)
  3. Offshore
    Mud with some bioturbation
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31
Q

These are deposited near shorelines thate experience STRONG TIDAL CURRENTS

A

Offshore Sand Ridges

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32
Q

Characteristcis by TIDAL OFFSHORE SAND RIDGES

A

Stacks of Cross-bedded and Cross laminated sandstone
Basal Lag Deposits (Lag is kapag naiwan ang coarse seds dahil nawinnow na ung fine particles can be alluvial, fluvial or tidal)

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33
Q

In a mixed storm-tidal shallow marine environment what is the characteristics of deposit

A

Shallow - Tidal
Offshore Transition - Storm

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34
Q

Forms when velocity of current is 50 cm/s

A

Low Relief Sand Sheets and Patches with ripple surface

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35
Q

Forms when velocity of current is 50-100 cm/s

A

Sandwaves (perpendiculat to the lfow with large-scale cross bedding)

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36
Q

Forms when velocty is >100 cm/s

A

Sand Ribbons (Parallel to the flow and have small scale cross bedding)

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37
Q

Huge sediment supply will cause sand ribbons to amalgamate and form

A

Sand Ridges

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38
Q

what is the distinctive characteristics of tide dominated clastic shallow seas

A

Shoreface is dominated by Cross bedded sands that contain fullt marin fauna and lack evidence for any subaerial exposure

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39
Q

The only force that can maintain large subaqueous dune or sandwae bedform

A

Tide

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40
Q

Reliable indicator of a Tidal Dominated Clastic Shallow Seas

A

Extensive Sheets and ridges of Cross Bedded Sand Deposit

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41
Q

Reliable indicator of a Storm Dominated Clastic Shallow Seas

A

HCS and SCS

42
Q

Another reliable indicator of shallow marine

A

Benthic Fossils

43
Q

Tempestite vs turbidite

A

Both Normally graded
Tempestite has HCS and SCS and has more diverse Ichnofacies
Turbidites are found in deep basin environment

44
Q

Lithology

A

Mainly SAND and MUD w/ Some gravel at the base

45
Q

Mienralogy

A

Mature qtz with Shelly Sands

46
Q

Texture

A

Mod to Well Sorted

47
Q

Facies Association

A

Overlain by Coastal Deltaic Estuarine or deeper marine Facies

48
Q

Shallow marine carbonate sedimetation areas

A

Carbonate platforms

49
Q

Two main conditions for carbonate sedimentation

A

1) Isolation from Terrigenous Clastic Supply
2) Shallow Marine Waters

50
Q

zone where with most favourable cinditions for biogenic carbonate prouction

A

Photic Zone

51
Q

Shallow region 10-20 meters of high biogenic productvity

A

Carbonate Factory

52
Q

carbonate platform attached to the land

A

Carbonate shelf

53
Q

Isolated carbonate platforms completelys surroounded by deep waters

A

Carbonate banks

54
Q

a carbonate bank formed above subsiding volcano

A

Carbonate atoll

55
Q

Assemblage in warm shallow seas where salinity is normal

A

Chlorozoan (Corals w/ Chlorophyta)

56
Q

Assemblage in warm restricted shallow seas where salinity is elevated

A

Chloralgal (Chloropyta only)

57
Q

Assemable in temperate cooler waters

A

Foramol (Forams and Mollusc)

58
Q

Texture of carbonates in Beaches

A

Well Sorted with Low Mud Matrix

59
Q

A fully lithified rock formed in caronate shallow environments when carbonate in solution precipitates and cements sand and gravel material on the beach

A

Beachrocks

60
Q

Dune sands that becomes wet calcium carbonate which is locally dissolved and reprecipitate to cement the material at the surface into a rock. (Lithified aeolian dunes)

A

Aeolianite

61
Q

Carbonate precipirated around roots of vegetation growing in dune sand may be preserved as

A

Nodula Rhizoconcretions

62
Q

Sites of FINE GRAINED sedimentation forming layers of Carbonate mudstones and Wackestone with some packstone and grainstone which are washovers near the beach barrier

A

Carbonate Lagoons

63
Q

Arid Carbonate Lagoons are characterized by these organisms

A

Stromatolites
Marine Grasses (Thalassia)

64
Q

Area of Hypersaline Shallow Water that percipitates evaporite Minerals

A

Saltern

65
Q

Area above the mean high water and is only indundateed by sewater under exceptional circumstance

A

Supratidal

66
Q

A hard lithified carbonate sand and dust cemented by microbes mud

A

Carbonate Pavement

67
Q

Arid Coasts very low relief and not always defined by beach

A

Sabkhas

68
Q

layers of anhydrite with remants of other sediments

A

Chicken wire structure

69
Q

Common sequence in a sabkhas

A

Subtidal Reworked Beds
Intertidal Microbial Limestone Beds
Chicken wire Anhydrite
Enterolithic Anhydrite

70
Q

Repeated precipitation of cements in this carbonate mud crust cuases the surface layer to expad and form a polygonal pattern of ridges also known as Pseudoanticlines

A

Tepee Structures

71
Q

A frabric characterized by patchers of Calcite cement that grow in the cavities in the host of lime mud

A

Fenestrae or Fenestral Cvities

72
Q

Lime mudstones with small cavities filled with calcite

A

Birds-Eye Limestone

73
Q

Algal and bacterial mats which trap fine grain sediment in thin layers to form well developed fine lamination of

A

Stromatolite

74
Q

Well sorted well rounded sediments composed of sand to granule sized loose carbonate material which occurs in high energy areas

A

Carbonate Shoals

75
Q

what is the orientation of a sedimentary body formed or reworked by waves?

A

Parallel to the Coastline

76
Q

What is the orinetation of a sedimentary body formed or rewerked by tides?

A

Perpendiculat to the shoreline

77
Q

Dome shaped reefs

A

Bio herms

78
Q

Tabular shaped reefs

A

Bio Stromes

79
Q

Hematypics (Have symbiotic relationships with algae) corals that are the main reef builders of the modern ocean

A

Scleractinian

80
Q

Unusual Mollusk reef Builder

A

Rudists ( Creteacous)

81
Q

Reefs in high energy reef crest

A

Encrusting massive

82
Q

Reef in lower energy deeper water

A

Branching, plate like

83
Q

Reefs in back reef

A

Globular

84
Q

A region of accumulation of carbonate breccia to form bioclastic rudstone (Clast supported Cabonate w/ 30mm clasts) and grainstone (Grain supported w/ no mud)

A

Forereef

85
Q

Sheltered from the highest energy conditions and is the site of deposition of debris removed from the reef core and washed towards the lagoon

A

Backreef

86
Q

Reefs built out directly from the shorelie and lack backshore

A

Fringing Reef

87
Q

Linear Reef Forms that parallel the shore line and is separeated by a back reef lagoon to the shoreline

A

Barrier Reefs

88
Q

reefs that develop in the shallow areas of the open ocean which are usually submerged remains of volcanic islands

A

Atoll Reefs

89
Q

Pre Mesozoic Group of Coral (Paleozic) which don?t have symbiotic relationship with algae

A

Rugose and Tabulata

90
Q

Mesosoic to modern day corals

A

Scleractinian

91
Q

sucessions in areas of fine grained pelagic carbonate deposition

A

Condensed Sections

92
Q

Sediment body consisting structureless or crudely bedded fine crystaline carbonate which are organic remains of microbes that had cacareous structures

A

Carbonate mud mound

93
Q

Lithified fine grained carbonate sediment in the outer platform settings

A

Chalk

94
Q

Generalized Carbonate Ramp Succession

A

Coarsening Up wih Increasing degree of sorting upwards reflecting higher energy conditions in shallow watr

95
Q

Storm deposits in Carbonate platforms are characterized by

A

Grainstones and Packstones (Grain supported)

96
Q

Generalize Rimmed Platform Sucessison

A

Basal slope Pleagic Mudstones and Carbonate Turbidite
Fore Reef Slope Deposit with Clinoform bedding
Forereef Rudstone
Reef Core Boundstones
Shelf Lagoon Wackestone

97
Q

Pattern created when a barred basin completely enclosed the water body will gradually shrink in volume and area with the most soluble salts in the center

A

Bulls-eye pattern

98
Q

Apttern created iwhen a barred basin is semi isolated and evaporation increases

A

Teardrop Pattern

99
Q

age during which Mediterranean sea have hypersaline conditions

A

Messinian Age (Messinian Salinity Crisis)

100
Q

Between Increase in Sediment supplu and Carbonate sedimentation, which would likely most happen when there’s a tectonic uplift?

A

Sediment supply

101
Q

What could promote carbonate sedimentation in a mixed carbonate-clastic environment

A

Sea Level Rise

102
Q

What can alternations between limestone and mustone/sandstone deposition possibly imply

A

Fluctuations in sea level