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GLE 2024 (Day 1) > STRATIGRAPHY AND SEDIMENTATION (SHALLOW MARINE) > Flashcards

STRATIGRAPHY AND SEDIMENTATION (SHALLOW MARINE) Flashcards

(102 cards)

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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
Where concave layers are preserved it is said to be
Swaley Cross Stratification
26
What Forms HCS and SCS?
Combined flow of Strong Storm Current and oscillatory motion of waves
27
What are the limiations of HCS and SCS?
Formed only on fine to meium grained sand deposited in offshore transition
28
Characteristics of a idealized tempestite?
(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
29
Characteritiscs of Offshore Zone?
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
30
Charactersitics of a Storm dominated Shallow Marine Envronment?
4. Foreshore Beach Deposit of Stratified Sands 3. 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) 1. Offshore Mud with some bioturbation
31
These are deposited near shorelines thate experience STRONG TIDAL CURRENTS
Offshore Sand Ridges
32
Characteristcis by TIDAL OFFSHORE SAND RIDGES
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)
33
In a mixed storm-tidal shallow marine environment what is the characteristics of deposit
Shallow - Tidal Offshore Transition - Storm
34
Forms when velocity of current is 50 cm/s
Low Relief Sand Sheets and Patches with ripple surface
35
Forms when velocity of current is 50-100 cm/s
Sandwaves (perpendiculat to the lfow with large-scale cross bedding)
36
Forms when velocty is >100 cm/s
Sand Ribbons (Parallel to the flow and have small scale cross bedding)
37
Huge sediment supply will cause sand ribbons to amalgamate and form
Sand Ridges
38
what is the distinctive characteristics of tide dominated clastic shallow seas
Shoreface is dominated by Cross bedded sands that contain fullt marin fauna and lack evidence for any subaerial exposure
39
The only force that can maintain large subaqueous dune or sandwae bedform
Tide
40
Reliable indicator of a Tidal Dominated Clastic Shallow Seas
Extensive Sheets and ridges of Cross Bedded Sand Deposit
41
Reliable indicator of a Storm Dominated Clastic Shallow Seas
HCS and SCS
42
Another reliable indicator of shallow marine
Benthic Fossils
43
Tempestite vs turbidite
Both Normally graded Tempestite has HCS and SCS and has more diverse Ichnofacies Turbidites are found in deep basin environment
44
Lithology
Mainly SAND and MUD w/ Some gravel at the base
45
Mienralogy
Mature qtz with Shelly Sands
46
Texture
Mod to Well Sorted
47
Facies Association
Overlain by Coastal Deltaic Estuarine or deeper marine Facies
48
Shallow marine carbonate sedimetation areas
Carbonate platforms
49
Two main conditions for carbonate sedimentation
1) Isolation from Terrigenous Clastic Supply 2) Shallow Marine Waters
50
zone where with most favourable cinditions for biogenic carbonate prouction
Photic Zone
51
Shallow region 10-20 meters of high biogenic productvity
Carbonate Factory
52
carbonate platform attached to the land
Carbonate shelf
53
Isolated carbonate platforms completelys surroounded by deep waters
Carbonate banks
54
a carbonate bank formed above subsiding volcano
Carbonate atoll
55
Assemblage in warm shallow seas where salinity is normal
Chlorozoan (Corals w/ Chlorophyta)
56
Assemblage in warm restricted shallow seas where salinity is elevated
Chloralgal (Chloropyta only)
57
Assemable in temperate cooler waters
Foramol (Forams and Mollusc)
58
Texture of carbonates in Beaches
Well Sorted with Low Mud Matrix
59
A fully lithified rock formed in caronate shallow environments when carbonate in solution precipitates and cements sand and gravel material on the beach
Beachrocks
60
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)
Aeolianite
61
Carbonate precipirated around roots of vegetation growing in dune sand may be preserved as
Nodula Rhizoconcretions
62
Sites of FINE GRAINED sedimentation forming layers of Carbonate mudstones and Wackestone with some packstone and grainstone which are washovers near the beach barrier
Carbonate Lagoons
63
Arid Carbonate Lagoons are characterized by these organisms
Stromatolites Marine Grasses (Thalassia)
64
Area of Hypersaline Shallow Water that percipitates evaporite Minerals
Saltern
65
Area above the mean high water and is only indundateed by sewater under exceptional circumstance
Supratidal
66
A hard lithified carbonate sand and dust cemented by microbes mud
Carbonate Pavement
67
Arid Coasts very low relief and not always defined by beach
Sabkhas
68
layers of anhydrite with remants of other sediments
Chicken wire structure
69
Common sequence in a sabkhas
Subtidal Reworked Beds Intertidal Microbial Limestone Beds Chicken wire Anhydrite Enterolithic Anhydrite
70
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
Tepee Structures
71
A frabric characterized by patchers of Calcite cement that grow in the cavities in the host of lime mud
Fenestrae or Fenestral Cvities
72
Lime mudstones with small cavities filled with calcite
Birds-Eye Limestone
73
Algal and bacterial mats which trap fine grain sediment in thin layers to form well developed fine lamination of
Stromatolite
74
Well sorted well rounded sediments composed of sand to granule sized loose carbonate material which occurs in high energy areas
Carbonate Shoals
75
what is the orientation of a sedimentary body formed or reworked by waves?
Parallel to the Coastline
76
What is the orinetation of a sedimentary body formed or rewerked by tides?
Perpendiculat to the shoreline
77
Dome shaped reefs
Bio herms
78
Tabular shaped reefs
Bio Stromes
79
Hematypics (Have symbiotic relationships with algae) corals that are the main reef builders of the modern ocean
Scleractinian
80
Unusual Mollusk reef Builder
Rudists ( Creteacous)
81
Reefs in high energy reef crest
Encrusting massive
82
Reef in lower energy deeper water
Branching, plate like
83
Reefs in back reef
Globular
84
A region of accumulation of carbonate breccia to form bioclastic rudstone (Clast supported Cabonate w/ 30mm clasts) and grainstone (Grain supported w/ no mud)
Forereef
85
Sheltered from the highest energy conditions and is the site of deposition of debris removed from the reef core and washed towards the lagoon
Backreef
86
Reefs built out directly from the shorelie and lack backshore
Fringing Reef
87
Linear Reef Forms that parallel the shore line and is separeated by a back reef lagoon to the shoreline
Barrier Reefs
88
reefs that develop in the shallow areas of the open ocean which are usually submerged remains of volcanic islands
Atoll Reefs
89
Pre Mesozoic Group of Coral (Paleozic) which don?t have symbiotic relationship with algae
Rugose and Tabulata
90
Mesosoic to modern day corals
Scleractinian
91
sucessions in areas of fine grained pelagic carbonate deposition
Condensed Sections
92
Sediment body consisting structureless or crudely bedded fine crystaline carbonate which are organic remains of microbes that had cacareous structures
Carbonate mud mound
93
Lithified fine grained carbonate sediment in the outer platform settings
Chalk
94
Generalized Carbonate Ramp Succession
Coarsening Up wih Increasing degree of sorting upwards reflecting higher energy conditions in shallow watr
95
Storm deposits in Carbonate platforms are characterized by
Grainstones and Packstones (Grain supported)
96
Generalize Rimmed Platform Sucessison
Basal slope Pleagic Mudstones and Carbonate Turbidite Fore Reef Slope Deposit with Clinoform bedding Forereef Rudstone Reef Core Boundstones Shelf Lagoon Wackestone
97
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
Bulls-eye pattern
98
Apttern created iwhen a barred basin is semi isolated and evaporation increases
Teardrop Pattern
99
age during which Mediterranean sea have hypersaline conditions
Messinian Age (Messinian Salinity Crisis)
100
Between Increase in Sediment supplu and Carbonate sedimentation, which would likely most happen when there's a tectonic uplift?
Sediment supply
101
What could promote carbonate sedimentation in a mixed carbonate-clastic environment
Sea Level Rise
102
What can alternations between limestone and mustone/sandstone deposition possibly imply
Fluctuations in sea level

GLE 2024 (Day 1) (34 decks)

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