Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geology- year 2 > Carbonates and Evaporates > Flashcards

Carbonates and Evaporates Flashcards

1
Q

carbonate rocks consist primarily of what two carbonate minerals

A

Limestone - predominately calcite (Calcium carbonate, CaCO3)

Dolomite - Predominately Dolostone (Calcium Magnesium Carbonate, CaMg(CO3)2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how are carbonate rocks formed?

A

through biological and biochemical processes and through inorganic precipitation from seawater

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what period did the spreading of carbonate rocks start with?

A

the Cambrian period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What percentage of all sedimentary rocks are made of carbonates? And what fraction do these carbonate rocks make up for the worlds petroleum reserves?

A

20-25%
and
1/3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Most carbonates form in what temperature of water?

A

Warm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

most carbonate sediments are generated in which zone?

A

Photic zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

True or fales.

Unlike sandstones, most carbonate grains are formed in the environment in which they are deposited?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Carbonates are not usually found / occur after approx. what depth? And why is that? And what is the name of that depth range?

A

3500-4000m and this is because the carbonate sediments dissolve here. This depth is called the Carbonate compensation Depth CCD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List 4 chemical carbonate rocks

A

Limestone
Dolostone
Rock Gypsum
Rock Salt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

List 3 BIOchemical carbonate rocks

A

Limestones (chalk and coquina)
Chert
Coal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Is Coquina a Clastic or Carbonate?

A

This was a trick question,

Coquina is a clastic carbonate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the major rock forming mineral found in mt.rundle?

A

Calcite (CaCO3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Carbonate reservoirs are predominately composed of what?

A

chemical precipitates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a chemical precipitate?

A

they consist of mineral matters that was precipitated at the place here the rocks first formed and not transported as clastic grains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the most dominate chemical reservoir rock?

A

Limestone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the secretion process? and what are formed by this process?

A

Rocks of biochemical origin are formed by this process in which animals and plants extract mineral material from solution and transform in into skeletal forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the carbonate secreted by living organisms? and how is it formed?

A

CaCO3 in the form of either aragonite or calcite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the main biochemical agents in forming limestones?

A

Algae, bacertia, corals, foraminifera, bryozoa, brachiopods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the most important rock builder of lime secretions and deposition?

A

Algae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the general way dolomite is formed?

A

formed from limestone as the calcium in calcite is partially replaced by magnesium. Usually as water solutions move through the limestone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

explain the process of dolomite recrystallization and it’s importance

A

Magnesium ion migration through layers of limestome form the dolomite and this replacement process causes the recrystallization of the pre-exisiting limestone which enhances the porosity of the carbonate rocks

22
Q

What are the two principal classifications for carbonates?

A

Folk’s classification: named after Robert Folk

Dunham’s classification: named after Robert Dunham

23
Q

How does Folk’s classification system work?

A

Based on the presence / absense of Allochem (carbonate particles or grains), matrix and type of cement

24
Q

How does Dunham’s classification system work?

A

It is based on texture of the rock.

25
Q

Limestones are formed in what environments (4)?

A

Shallow marine
deep marine
karsts
Lakes

26
Q

High temperature and low pressure and breaking waves favor what?

A

carbonate precipitation

27
Q

CaCO3 precipitates in warm or cool water?

A

Warm shallow water

28
Q

What are the four controls on carbonate accumulation?

A

Temperature
Light
Agitation of waves
Organic activity

29
Q

Are carbonate sediments born or made?

A

Born

30
Q

What are the four carbonate platforms?

A

Ramp
Rimmed Shelf
Epieric platform
Isolated platform

31
Q

What is the Carbonate mineralogy consist of?

A

Aragonite - high temp CaCO3 mineral
Calcite - Stable in sea water and near surface crust
Dolomite - stable in sea water and near surface

32
Q

Lime muds and skeletal material are lithified into what?

A

Limestone

33
Q

What are the four keys for the interpretation of a depositional setting of a carbonate?

A

Grain types
Grain packing or fabric
Sedimentary structures
Early diagenetic changes

34
Q

What is an Ooid?

A

spherical grains formed by calcite precipitation around the nucleus. Such as shell fragment

They are less than 2mm in diameter

35
Q

Where are Ooids found/formed?

A

Typically form in shallow warm , agitated and carbonate - saturated waters such as those near the bahamas.

36
Q

What kind of sedimentary structures are present in carbonate rocks?

A

Cross bedding
Laminated bedding
Mud cracks
Trace fossils

37
Q

What are two carbonate marine depositional systems?

A

Carbonate reefs

Carbonate shelves and platforms

38
Q

What are four examples of Carbonate tectonic extension settings?

A

Great barrier reef of Australia
Bahamas
East Africa
Red Sea

39
Q

What are three examples of Carbonate tectonic Compression settings?

A

Persian Gulf
Appalachians
Australia

40
Q

What is a Karst?

A

a landscape formed by the dissolution of soluble rocks including limestone, dolomite and gypsum

41
Q

What is a Karst modified reservoir?

A

Carbonate reservoir

42
Q

Examples of Karst features that can affect reservoir performance

A

Collapse feature
Residual Paleo-Highs
Solution - enlarged fractures

43
Q

What are Two factors that shape coral reefs?

A

The foundation on which they grow

sear level history

44
Q

What are the three major reef types?

A

Atoll
Fringing
Pinnacle / Barrier

45
Q

What is an Atoll reef?

A

circular reef enclosing lagoons

46
Q

What is a Pinnacle reef?

A

shaped like a tower and rises from the sear floor to form mounds

47
Q

What is a fringing reef?

A

they grow attached to the shoreline or island

48
Q

Name four carbonate depositional environments

A

Shelf (reef) margin crest
Shelf Platform
Basin
Shelf base

49
Q

What is a reef margin

A

forms linear bodies parallel to the basin

50
Q

Why are shelf platform carbonate depositional environments important?

A

they form major caps to oil fields.

51
Q

What is important to know about the shelf margin slope system?

A

Gravity dominant sedimentary driver

52
Q

What is important to know about the basin systems?

A

they are set in the deeper water down slope

they tend to exhibit thin beds of alternating carbonates, silts and shales

Geology- year 2 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions