SEDIMENTARY PETROLOGY (BIOCHEMICAL ROCKS) Flashcards
1
Q
Boundary between high and low Mg Calcite
A
4% Mg
2
Q
Immiscibility Gap
A
25-40% Mg
3
Q
Dolomite Boundary
A
40-55% Mg
4
Q
Which is more abundant high Mg or Low Mg?
A
High Mg Calcite
5
Q
Calcite crystal system
A
Hex
6
Q
Aragonite crystal system
A
Ortho
7
Q
Arrange Aragonite, HiMg Calcite and LowMg Calcite in terms of stability in Meteoric Waters
A
Low Mg Calcite
High Mg Calcite
Aragonite
8
Q
Where is Dolomite More abundant?
A
In older Rocks (Abundance decreases with younging age)
9
Q
Organisms which have distinctly Low Mg Skeletal compositions
A
Cyanobacteria
Cocoliths (Algae)
Planktonic Foram
Rugose Corals
Tabulate Corals
Belemnites
Trilobites
10
Q
Organisms which have distinctly High Mg Skeletal compositions
A
Rhodophyta (Red Algae)
Sponges
Alcyonarians (Anthozoan)
Decapods (Crabs)
11
Q
Organisms which have distinctly Aragonitic Skeletal compositions
A
Chlorophyta (Green Algae)
Scleractian Corals
Bryozoans
Brachiopods
Pteropods
Cephalopods
12
Q
Both High and Low Mg Calcite
A
Echinoderms
Ostracods
Benthic Forams
13
Q
Both Low Calcitic and Aragonitic
A
Stromotoporoids
Bivalves
Gastropods
14
Q
Varying of the three
A
Serpulids (Annelids)
15
Q
Conditions for carbonate Preservation
A
1) High Carbonate Production and Preservation
2) Low Detrital Input
16
Q
Depositional Environmets where Carbonates are favorably formed
A
1) Low Relief, Tectonically Stable Areas
(Passive Margins, Intracratonic Seas where cratons are flooded during sea level high stands)
2) Shallow areas far from Continents
(Oceanic Platforms, Oceanic Islands, Sea Mounts and Oceanic Ridges)
17
Q
young carbonates
A
Aragonite and high Mg Calc
18
Q
Old Carbonates
A
Dolomite and Low Mg Calc
19
Q
Favorable conditions for Carbonate Production
A
1) Shallow Areas of Photic Zones where sunlight is abundant
2) Nutrient Rich Shallow Waters
3) High Temp, Wave Agitated,
Low CO2, highly Alkaline (Kasi pag acidic magdidissolve)
20
Q
Marks the ocean depth at which carbonate shells sink and undergo dissolution due to acidic and cold water
A
Lysocline
21
Q
The depth below which CaCO3 sediment do not accumulate
A
Carbonate cemponsation depth
22
Q
When Detrital influx exceeds carbonate production what type of rocks are formed
A
Carbonate -Bearing Detrital Seds
23
Q
Terriestrially produced Carbonate Seds
A
1) Speleothems from Groundwaters
2) Travertine (Hot) and Tufa(Ambient) found around springs
3) Carbonate Seds precipitated from lacutrine envi
24
Q
Sand and/or gravel sized carbonate particles
A
Allochems or grains
25
Examples of Allochems
1) Shells and other skeletal particles
2) Spherical Ooids
3) Clasts of Carbonates - Limeclasts
4) Peloids - Smaller pellet size
26
Roughly spherical concentrically laminated Sand Size <2mm particles that possess a nucleus
Ooids
27
How do ooids form?
Accretion of CaCO3 laminae about a particle of shell fragment or sand that acts as a nucleus for precipitaitio
28
this bacteria is said to aid in the precipitation of ooids
Cyanophytes
29
What environments is being indicated by the presence of ooids in the deposit?
Shallow Marine dominated by wave and/or tidal current in a tropical to subtropical settings
30
larger than ooids usually >2mm in diameter
Pisoids
31
Allochem of Gravel-Size Clasts of Cohesive Carbonate sediment
Limeclasts
32
When clasts are said to be derived from nearby coeval deposits they are called
Intraclasts
33
When rarer clasts are derived from erosion of older source rocks outside the depositional area
Lithoclasts or Extraclasts
34
Type of limeclast consist of cemented grains rather than cohesive muds
Aggregates
35
Type of aggregate limeclast which consist of cemented grains such as ooids that resmeble bunches of grapes
Grapestone
36
Aggregate limecalsts that have a colloform coating of carbonate laminations
Botryoidal grains
37
Smaller sand-size carbonate grains composed of carbonate mud that resembles fecal pellets no iternal structure
Peloids
38
Fecal pellets
Excreted by sediment feeding orgaism
39
How are peloids formed
1) Micritization of Ooids
2) Erosion of coehsive lime muds
40
Silt and clay size carbonate particles or simply carbonate mud
micrite
41
Coarser Carbonate Mud
MicroSpar
42
Formation of Micrites
DIRECT (Secretion and Precipiation)
INDIRECT (Micritization and Abrasion)
1) Secretion by Chlorophyta (Green Algae)
2) Micritization of pre-existing carbonate by microbes
3) Mechanical abrasion of pre-existing carbonate grains
4) Precipitation from solution
43
Grabaur Textural Terms
Rudite - Gravel
Arenite - Sand
Lutite - Mud
44
Prefix used for Field Classification using hand lends and dilute HCL and staining
Calci (a) - Calcite
Dolo (a) - Dolomite
45
Effects of staining calcite and Dolomite with Alizarine Red-S
Calcite - Pink
Dolomite - No Change
46
A classification system whch emphasizes TEXTURE of carbonate rocks coming up with six major varieties of Carbonate Rocks ( the fifth classification based on inferred origin and sixth orig texture could not be recognized)
Dunham Classification System
47
Mudsupported Carbonate with <10% Grains
Mudstones
48
Mudsupported Carbonate with >10% Grains
Wackestones
49
Grain Supported which contained Mud Matrix (Closed System)
Packstones
50
Grain Supported which do not have Mud Matrix but rather have interstitial diagenetic cements
Grainstones
51
In Situ Carbonate Accumulation such as Reefs and Stromatolites which were ORGANICALLY Bound at the time of Accumulation
Boundstones
52
Subdivision of Boundstone produced by organisms that BUILD RIGID ORGANIC STRUCTURES or FRAMEWORK such as REEFs by SECRETION
Framestone (Reefs)
53
Boundstone produced by organism that build ORGANIC STRUCTURES such as STROMATOLITES and REEFS by BINDING and/or ENCRUSTING pre existing Carbonate Material
Bindstones (Stromatolites)
54
Boundstone Produced by Organism that TRAP ORGANIC CARBONATE SEDIMENT by acting as BAFFLES which hinder its movement across bed
Bafflestone (Bioherms)
55
Carbonate Gravel-bearing rocks with a CLAST SUPPORTED FRAMEWORK
Rudstone
56
Carbonate Gravel bearing rocks with a Matrix Supported Framework
Floatstone
57
Carbonate rocks consist of COARSELY CRYSTALLINE CaCO3 PRECIPITATED DIRECTLY FROM SOLN
Crystalline Carbonate
58
Rocks in Dunham which is cosidered to be excellent reservoir rock
Grainstones and Rudstones
59
Rocks in Dunham which is considered to be excellent trap
Mudstones, wacksestones, floatstones
60
Four major Grain or Allochem types according to Folks classification
1) Intraclasts (Limeclasts)
2) Oolite
3) Skeletal Fragments
4) Peloids (Pellets)
61
Short for microcrytsalline calcite and used to name a carbonate mud
Micrite
62
In folk's classification intergranular cement which are precipitated in pore spaces between allochems during diagenesis
Sparry Cement or Spar
63
Folk's Classifications depend mainly on
1) Percentage of Allcohems
2) Ratio of Spar and Micrite
64
Generally Micritic Carbonate rocks are deposited in
Periodically Calm Environments
65
Generally Sparry Carbonate rocks are deposited in
Agitated Environments
66
25% of Intraclasts w/ diagenetic cement
Intrasparite
67
25% of Intraclasts w/ Mud Matrix
Intramicrite
68
25% Ooids <25% Intraclasts w/ Diagenetic Cement
Oosparite
69
25% Ooids <25% Intraclasts w/ Mud Matrix
Oomicrite
70
Fossil dominated grains w/ Diagenetic Cements
BioSparite
71
Fossil dominated grains w/ Mud Matrix
BioMicrite
72
Pellet Dominate grains w/ Diagenetic Cement
PelSparite
73
Pellet Dominated grains w/ mud matrix
PelMicrite
74
Rocks composed primarily of Carbonate Mud
Micrite
75
Micrite that contain small spar-filled voids
DisMicrite
76
In Situ Carbonate Accumulations
Biolithite (Boundstone)
77
Three Major Textural Groups of Folks
1) Micrites = >2/3 Mud Matrix
2) Sparites = >2/3 Diagenetic cement
3) Poorly Washed Sparites = 1/3 spar and 1/3 micrite
78
Division of Micrites based on % Allochems
1) Micrite <1% Allochems
2) Allcohemical Micrite 1-10%
3) Sparse Allochemical Micrite (Wackestone)10-50%
4) Packed Allochemical Micrite (Packestone)
>50%
79
Divisions of Sparites based on sorting and roundess
1) Unsorted Sparite
2) Sorted Sparite
3) Rounded Sparite
80
Supratidal
above High Tide line
81
Intertidal (Foreshore)
High Tide Line - Low Tide Line (mixed high and low energy environments)
82
Subtidal Shoal (Shoreface)
Constantly disturbed by waves and currents
83
Subtidal (Offshore Transition)
periodically disturbed by storm waves
84
Subtidal (Offshore)
Calm
85
Barrier Reef
wave resistant organic accumulation that rise above the surrouding seafloow;
BANKS and MOUNDS are organic accumulations without reef properties
86
Lagoons
Calm, shallow water areas on landward side of rimmed platform reefs and sand shoals
87
Deep Pelagic
Deposits settle from suspension in offshore
88
Deep Mass Flow
Deposits for submarine rockfall, slides, debrie flow and turbidity currents
89
An ideal model of carbonate depositonal environment with a gentle slope towards the deep sea over distances of 10-1000km and typically develops on margins of shallow subtropical seas (important na subtropical to allow carbonate accumulation)
Carbonate Ramps
90
Develop near shelf or platform margins where nutrient rich water upwell from depth cause carbonate buildups which creates reefs, sand shoals and lagoons landward and steeply dipping forereef deposits seaward
Rimmed Platforms
91
Carbonate depositional environments develop during marine transgressions when ocean flood large portions of the craton to form shallow seas and where carbonate show patchwork depositional pattern Wrapping up in upwarped areas and encircling susiding basins (Bull's eye pattern
Epeiric Sea platform
92
Develop on volcanic seamounts or platforms separated from land by a considerable distance and in which carbonate build up develops on platform margins and encloses a lagoon between them. Reefs are on the winward side of the platforms and shoals are on the leeward side of the lagoon
Isolated carbonate platforn
93
Occur in deepwater settings below the wave base and above the CCD and are characterized by pelagic sediment deposition
Submerged Carbonate platform
94
Local accumulations of carbonate sediment that possess significant relief above the surrounding sea floor
Carbonate Buildups
95
Carbonate in situ builds up by organic activities
Bioherm or biostrome
96
Bioherm which secrete skeletal materials
Framestone
97
Bioherm which encrust or bind together
Bindstone
98
Bioherm which traps grains or muds
Bafflestones
99
Biostromes in which organisms have built relatively rigid, wave resistant structures over substantial periods of time
Reefs
100
Reefs that develop adjacent to and fringe shorelines
Fringing Reef
101
Reef that are separated from the shoreline by a lagoon
Barrier Reef
102
Roughly Circular reefs that encloses a lagoon without major land masses
Atoll
103
Small isolated high relief reefs
Pinnacle Reefs
104
Small isoated low relief reefs
Patch Reefs
105
Formerly active reefs drowned during subsidence or sea level rise
Submerged Reef
106
opposite of Greenhouse
Icehouse lowered CO2
107
The proportion of energy reflected back from the surface
Albedo
108
controls of Carbonate Diagenetic Reactions
Pore Fluid Geochemistry
1) Alkalinity-Acidity
2) Temperature
3) Total Dissolved Solids
4) Dissolved Mg/Ca Ratios
5) Dissolved Sulfate Ions
109
How can sea water be more acididc
Dissolved CO2
110
Three Carbonate diagenetic environment with their associated pore fluid
1) Sea Floor - Marine Connate Waters
2) Below Land Surface - Meteoric Waters
3) Zone of Mixing - Meteoric and denser marine waters
111
Non-saturated meteoric zone above the water table
Vadose Zone
112
Saturated meteoric zone below the water table
Phreatic Zone
113
Important source of mud generated during EODIAGENESIS by blue green endolithic microbes that inhabit carbonate sediments (ooids, skeltal particles)
Microbial Micritization
114
porosity and permeability change during compaction
Decreases
115
Selective dissolution at the portions of grains under maximum stress especially at grain contact
Pressolution
116
A texture produced by extensive pressoluton which causes interpenetration of carbonate grains
Fitted Fabric
117
Process which leaves insoluble residue of non carbonate minerals
Dissolution
118
Insoluble residue seams that cross cut partially dissolved grains and commonly have a toothed pattern
Stylolites
119
Thicker seams of insoluble residue that ofte anastamose to produce braided pattern
Dissolution seams
120
Between Meteoric and Marine water which is more acidic?
Meteoric Water (Lower Mg/Ca ratio)
121
What type of Carbonate minerals is more susceptible to dissolution by meteoric water during diagenesis?
Aragonite and High Mg Calcite
122
Dissolution of which produces
Moldic Porosity
123
A mineral cement mainly composed of Aragonite and High Mg calcite
Marine Cements
124
Cement or coatings of constant thickness and characteristics of ocean floor sedimens
Isopachous Rim Cement
125
A mineral cement exclusively composed of low Mg Calcite
Meteoric Cement
126
A meteoric cement which involves nucleation on host grains of multple crystals that grow outward into pore spaces to produce a fringing crystals w/ straight boundaries whose size increases away from the host grains
Drusy calcite cement
127
involves precipitation of low mg calcite that nucleates in optical continuity with a low mg calcite cement and are common on single cystal echinoderm crystal
Syntaxial Calcite cements
128
cement which consists of a single crystal large enough to incorporate multiple grains during its growth
Poikiloptic Cement
129
Cements in Phreatic Zones
Drusy Calcite (Fringing outwards)
Syntaxial Calcite (Optical Coninuity)
Poikiloptic Calcie (Massive large crystal)
130
Cements which develop on grain bottoms which hang downward from the grain
Pendant Cement
131
Cements form between grains that may resemble an hour glass
Meniscus Cement
132
Coments in Vadose Zone (Unsaturated Zone)
Pendant Cement (Hanging downward grain bottom)
Meniscus Cement (In between adjacent grains like an hour glass)
133
Process in carbonate rocks in which new crystals form without significant change in composition
Neomorphism
134
Neomorphic Sparry Caclite fromed from Micrite
Psuedospar
135
Period of Sea level transgression chracterized by high Dolomitization
Ordovician to Devonian
Jurassic - Cretaceous
136
Formational Conditions for Dolomite
High Mg/Ca
Reduced SO4
137
Areas with favorable conditions for PRIMARY Dolomite formation
Subtropics where there is evaporation and subsequent precipation of Aragonite and Gypsum
In saline lakes contaminated by High MG Grounwater (Saline lakes have sulfate reducing bacteria)
138
Mechanism of dolomite formation wherein dense brines percolate downwards through carbonate sequences
Reflux or Evaporative Drawdown
139
A type of convective mechanism which suggest deep circulation of dolomitizing fluids
Kohout Convection
140
This is the one responsible for keeping SO4 levels at reduced conditions which favor dolomitization at subsurface diagenetic environments
Bacterial reduction of sulfate
141
sed rocks fromed by chemical PRECIPITATION from highly saline waters (brines) that have become oversaturated with respedt to one or more dissovled solids
Evaporites
142
Evaporites are important _______________ in petroleum systems
Cap rocks or seal
143
how much of the sed rock record is the evaporite?
1%
144
latitudes which satisfies climactic conditions for evaporite formation
10-30 deg latitude from the equator (Subtropical)
145
Areas in high latitude which favors evaporite formation
Rainshadow Deserts
146
Marine Evaporite Sequence from Sea Water Evaporation
least soluble to most soluble pattern
147
50% water evaporated
Calcite
148
75% water evaporated
Gypsum
149
90% water evaporated
Halite
150
>96% water evaporated
Potassium and Magnesium Minerals
151
Warm Arid shallow marine lagoons with very low relief
Sabkhas
152
Where are sabkhas situated?
Transition zones between Arid Marine and non-marine environments
153
Best Known Sabkhas
Trucial Coast, Persian Gulf
154
What usually form in the intertidal to supratidal zones?
Carbonates and Gypsum
155
sequence of Formation from upper intertidal to supratidal at the top of the water table (Landward)
Bladed Gypsum
Roseiform Gypsum
Nodular Gypsum (Vadose Zone)
-dehydration due to increasng temp supratidal-
replacement anhydrite
chicken wire anhydrite
156
a pattern which shows the sequential precipitation of evaporites which is the function of evaporation rates, such pattern reflects INCREASED SALINITY and DECREASED subaerial water coverage as evaporation and isolation proceeds
Bull's eye pattern
157
When are evaporites relatively rare
Precambrian
158
Carnellite
K Mg Halide
159
Kainite
K Mg Sulfate Halide
160
Polyhalite
Ca, Mg, K halide
161
Bischofite
Mg Halide - Scarce
162
Sylvite
KCl
163
Langbenite
K Mg sulfate - Scarce
164
Keiserite
Mg sulfate hydrated
165
Lakes situated in arid environments that have seasonal filling
Playa Lake
166
Sabkhas: Marine = ____________: Lacustrine
Playa Lake
167
Common pattern of lacustrine evaporite deposits
Bulls eye
168
Mineral Indicators of Lacustrine Evaporite Deposits
Borax
Epsomite (Mg sulfate - hyrdated)
Gaylussite (Carbonate)
Glauberite
Natron
Trona (Carbonate)
Ulexite
169
Differentiate qtz, chalcedony, opal and chert
1) qtz is crypto-macrocyrtalline mineral
2) Chalcedony is a cryptocrystalline radial-fibrous silica variety
3) Opal is amorphous
4) Chert is a rock composed of these minerals
170
Ogranisms that secrete opaline silica
Diatoms
Radiolaria
Silica Flaggelates
171
site of deposition of silica rich deposits
Below cCD
172
During diagenesis opaline silica shells are converted to a partially crystalline form of silci
Opal-CT
173
Chert that is part of layered sequence
Bedded Chert
174
Chert interstratified with mudrocks
Ribbon Chert
175
Cherts which occur as ellipsoidal to bulbous to irregular masses less than 1m in length that tend to be elongate, parallel to and concentration In certain strat
Nodular chert or secondary or replacement cherts
176
siliceous deposits precipitated in hot springs
Siliceous sinters
177
Minimum iron by weight of ironstones
15%
178
Different types of Iron Rich Sed rocks
1) Precambrian Iron Formations
2) Phanerozoic Iron Stonees
3) Bog Iron, Fe-Mn Nodules, Pyrite-rich Shales
179
Laminated to thinly bedded iron formations of Iron bearing minerals interlayered with chert and accounts for 60% of worlds iron ores
Banded Iron Formations
180
iron rich Serpentine
Greenalite
181
Iron rich Chlorite
Stilpnomelane and Chamosite
182
Iron rich Talc
Minnesotaite
183
Common age of BIFs?
Archean to Paleoproterozoic
184
BIFs which dominate Archean Iron rich sed rocks and tend to be faily thin (<10-100m), elonagate lenses limited lateral extents associated with ultramafic to mafic volcanic rocks which have been formed in deep marine environments
Algoma-type
185
Iron rich fine grained rocks in the Archean BIFs
Femicrites
186
Type of BIFs which dominated the Proterozoic and tend to be mush larger than the archean ones
Superior-type
187
Iron sequence with ooids, pisolithsm intraclasts and pellets
Granular Iron Formations
188
What might be the source of Archean BIFs
1) Iron originated from Hydrothermal Vents
2) Silica is precipitated from Acidic waters that leached continental rocks
3) Chemical stratification leads to its layering
189
What might be the source of superior type BIFs?
Cyanophytes - Microbial induced precipitation of iron
Non microbial precipitation of silica
190
Phanerozoic Iron Rich sed rocks
Ironstones
191
Predominant minerals in iron stone
Geothite and Hematite
192
Two peaks of Ironstone formation which corresponds to maximum global warming and Marine Transgression
Jurassic-Cret
Ordovician-Devonian
193
Iron formation which form where acidic groundwater delivers ferrous ions into swamps and lakes where it is oxidized and precipitated as surface crusts
Bog Iron Deposits
194
Iron formation foe\rmed under oxidizing conditions on the sea floor where iron and manganese oxides precipitate along with other base metals
Polyminerallic Manganese Nodules
195
What's the source of iron-rich black shales?
Hydrothermal precipitated chimneys aroun black smokers
196
Minerals which give black smokers back color
Pyrite and Chalcopyrite
197
Amorphous apatite
Collophane
198
apatite of bones and teeth
Hydroxy-Apatite
199
Apatite cryptocrystallinite
Fluor-Apatite
200
Rare phosphate rich rocks
Phosphorites (50% phosphate minerals and/or 20% phosphate by wt)
201
Consists primarily of plant material (Wood, leaves, mosses, grasses and phytoplanktons) that have been buried, compacted and heated and biochemically altred during diaganeses
Coal
202
Areas of Coal Fomation
1)Paralic Shoreline Environments
2) River Floodiplains
3) Shores of shallow lakes, cratonic or continental rift valley settings
4) Poor Drainage Areas
203
Thick dense deposits of organic material that accumulate over long periods of time
Peat
204
Progressive transformations during coal formations driven by increasing temp and a bit of pressure increase
Coalification
205
Why are there no coals older than Devonian?
Because woody plants start to inhabit land only during Devonian
206
Soil orders associated with Coal
Histo and Verti
207
Coal ranks based on progressive changes in composition, texture and appearance
Lignite
Sub-bituminous
Bituminous
Anthracite
208
Other trends that is a function of coalification
1) Increasing Carbon Content
2) Gradual Color Change from Brownish to Blakish
3) Decrease Moisture and volatile content
4) Increasing hardness and compactness
5) increasing reflectivity
209
Reflective organic compounds that starts to form with sub-bituminous formation
Vitrinite
210
Low rank of Coals or soft Coals
Lignite and Subbituminous
211
Primary use of Soft Coals
fuels in electric powerplants
212
What can be the detrimental effects of burning soft coals?
production of airborne pollutants since they have high volatile content
213
Compact, hard, black and somewhat reflective
Bituminous
214
High ranking bituminous Coal
Coking Coal
215
Whats the use of high ranking bituminous coal
Steel making
216
Cleaning burning coalwhich is only less than 1% of the coal worldwide
Anthracite
217
Carbon content
50-70
70-80
80-90
>90
218
Volatile content
45-55
40-50
25-40
5-15
