Exam 3- Geology 1001 Dominique Garello

Fault metamorphism can result in which texture?

mylonite

What type of metamorphic rocks are typically composed of just one mineral type, with equidimensional crystals that do not have a preferred orientation?

Non-foliated quartzite or marble

A metamorphic rock, like in the picture below, has aligned minerals orientated in the same direction, but does not contain planar fabric(layers). What metamorphic texture does the rock have?

lineation

Which of the metamorphic rocks listed does not have foliated texture? 

Quartzite

What does the presence of the index mineral, chlorite, in a metamorphic rock indicate?

The rock has experienced a lower degree of metamorphism (low grade metamorphism) with lowest of pressure and temperatures for metamorphism.

Comparing the metamorphic processes for various tectonic settings, which would you conclude to be most likely to occur along a mid-ocean spreading center?

Hydrothermal metamorphism

the repetitive layering or planar alignment of mineral grains in metamorphic rocks, formed primarily due to differential stress during metamorphism.

foliation

Metamorphism in low pressure, high temperature conditions and associated with magma intrusions

contact metamorphism

Metamorphism that can occur in a wide range of temperatures and pressures and is associated with crustal thickening, mountain formation in convergent settings

Regional metamorphism

A shear zone in which rocks behave ductility and produce mylonite metamorphic rocks due to directed stress

fault metamorphism

Low-grade metamorphism when sedimentary rocks reach depth to produce non-foliated metamorphic rocks

Burial metamorphism

Metamorphism in high pressure, low temperature conditions and forms blueschist and eclogites

Subduction metamorphism

What metamorphism occurs along continental collision settings?

regional and fault metamorphism

Which type of metamorphism occurs at a relatively low temperature and high pressure environment, and the diagnostic metamorphic rock is blueschist.

Subduction zone metamorphism

Non-foliated metamorphic rocks form by which metamorphic process?

Recrystalization

What process forms new minerals during metamorphism?

solid state diffusion

Which of the following metamorphic rocks forms from the sedimentary rock, shale?

schist

Which of the following trends occurs as metamorphic grade goes from low to high grade?

mineral grains get larger, foliation become more distinct

Schistosity is an example of which type of physical metamorphic process?

rotation of minerals

Which causes minerals to deform, rotate, flatten or stretch?

directed stress

In what environments does low pressure/high temperature metamorphism occur?

near magma intrusions at shallow depths

Which of the following is not a common metamorphic process?

Complete remelting of rock

Broadly, metamorphism involves __________.

changes in mineralogy and texture in response to heat and stress

Which is not an example of indirect evidence of past life that indicates an activity or behavior of past life (a trace fossil)?

teeth

_____ correlations establish a similar age of strata based on the lithology that is the composition and physical properties of that strata.

Lithostratigraphic

The process of establishing which sedimentary strata are the same age at distant geographical areas by means of their stratigraphic relationship is called_____

Stratigraphic correlation

Often lithostratigraphy is challenging because different lithologies of sedimentary rocks can form at the same time at different geographic locations because depositional environments vary geographically. To link strata without using lithology, geologists can use____

Chronostratigraphic correlation

______ correlation uses index fossils to determine strata ages. Index fossils represent assemblages or groups of organisms that were uniquely present during specific intervals of geologic time.

Biostratigraphic

The Principle of Faunal Succession is based on the observation that

fossil organisms appear in a consistent linear order.

Petrified wood or fossilized bones are a type of

permineralized fossil

When the original material of the organism dissolves and leaves a cavity in the surrounding rock forming ____

molds and casts fossils

A rare form of fossilization where the original materials or hard parts of the organism are preserved is when

actual preservation (unaltered remains)

_____ occurs when an organism is buried, and then elements in groundwater completely impregnate all spaces within the body, even cells and replacing the original material.

permineralization

_____ fossils occur when organisms are compressed and only the carbon remains providing a carbon silhouette of the organism.

carbonization

Dendrochronology involves dating of historic and geologic events through the study of

annual growth rings in trees

As understood by modern geologists, the principle of uniformitarianism implies that

physical processes observed today (such as erosion and volcanic eruptions) have been active in the past at roughly the same rates

Which time division is the largest of Earth's geologic timescale?

Eons

Choose the correct order of Earth’s geologic Eras from oldest to youngest.

Precambrian, Paleozoic, Mesozoic, Cenozoic

Within the world's sedimentary rocks, fossils

occur in an ordered sequence

A fossil of an organism that lived during a relatively short period of time over a large area on Earth (widespread), and can be used for stratigraphic correlation is called

index fossil

The Earth is approximately how old?

4.6 billion

Which statement best summarizes the development of the geologic time scale?

Relative ages for sedimentary strata were known before accurate numerical ages for these rocks were measured.

Two atoms of a single element that differ in number of neutrons are said to represent two distinct __________ of that element.

isotopes

What are the factor(s) that increase the chance of an organism getting preserved as a fossil? Choose all that apply.

b- how fast it was buried

c-if the organism had hard parts, like bones

Which statement is incorrect about radiocarbon dating?

It involves nitrogen -14 isotope decaying to the carbon-14 isotope

What is the difference between absolute age and relative age?

Numerical age gives the number of years between the event and the present, whereas relative age places events in sequential order.

____ is where sedimentary strata are deposited on a terrain developed on top of sedimentary strata that have been deformed by tilting, folding, and/or faulting, so that they are no longer horizontal.

Angular Unconformity

____ are unconformities that occur between parallel layers of strata indicating either a period of no deposition or erosion.

Disconformity

____ is where sedimentary strata are deposited on crystalline (igneous or metamorphic) rocks.

Nonconformity

A geologist comes across an outcrop with a large unconformity. What can be interpreted by this observation?

There was an erosional event that formed the unconformity

What is the main purpose of absolute dating in geology?

To determine the exact numerical age of rocks and fossils

The term half-life represents the time it takes

for half the parent atoms to decay into daughter (child) atoms

The principle of _____ states that within the depositional basin, strata are continuous in all directions until they thin out at the edge of that basin.

Lateral Continuity

The principle of _____ states that layers of rocks deposited from above, such as sediments and lava flows, are originally laid down horizontally.

Original Horizontality

The principle of ____ states that deformation events like folds, faults, and igneous intrusions that cut across rocks are younger than the rocks they cut across.

Cross-cutting Relationships

The principle of ____ states that fossils occur in strata in a definite, determinable order and this systematic change of unique fossils through time due to evolution, can be used to correlate rocks of the same age across a wide geographic distribution.

Fossil Succession

The principle of ____ states that in an otherwise undisturbed sequence of sedimentary strata, or rock layers, the layers on the bottom are the oldest, and the layers above them are younger.

Superposition

For a material that undergoes radioactive decay, after three half-lives has passed, how much of the original parent radioactive isotope remains?

12.5%

Which is not a proxy indicator of paleoclimate? 

chemistry of igneous rock layers

What is not evidence of our current global climate change?

Increase in land above sea level as coastlines recede/regress

The development of the Antarctic Circumpolar Current, and formation of the Himalayan Mountains played a role in what paleoclimate event?

Global cooling in the Cenozoic to the present

What evidence do we have that proves anthropogenic fossil fuel burning rather than changes in rock weathering or volcanic activity are responsible for major CO2 changes in the atmosphere in the last two centuries?

Isotopes of carbon clearly fingerprint fossil fuel burning as being responsible.

When global warming thaws permafrost this leads to decay and oxidation of once frozen organic matter causing carbon dioxide and methane to be released into atmosphere resulting in further global warming. This is an example of

a positive feedback mechanism.

Which reservoir of the carbon cycle hold carbon the longest?

Limestones

Which is not one of the common greenhouse gases?

sulfur dioxide

Which proxy indicator has provided over 800,000 years of climate records from the chemistry of ancient atmosphere trapped in air bubbles?

Ice cores

Prolonged stretches of above-average volcanic activity (such as flood basalt events) and significant mountain-building events (causing an increase in the weathering of rocks) can upset the balance of what?

Carbon cycle

Models used by the Intergovernmental Panel on Climate Change show that by the year 2100, the average annual temperature will have increased in some parts of the world by as much as

4°C

Which of the following best describes the Earth's climate history?

Temperatures on the Earth have varied throughout geologic time

The _________ is when gasses in Earth's atmosphere prevents heat from Sun's energy or Earth's heat from escaping into space.

Greenhouse Effect

Which is not part of the geological carbon cycle? (As opposed to the other part of the carbon cycle: biological carbon cycle)

Living organisms consume carbon dioxide from atmosphere through photosynthesis and take that carbon to make their tissues and substances.

Records of oxygen isotope (18O/16O) data from corals, microorganisms, and ice cores are used as a proxy for

Past global temperature

The rise in sea level, due to global warming, is largely a result of which? choose all that apply.

a- Melting of glaciers

b-Thermal expansion of sea water

With global warming, changes to the ocean circulation (ocean conveyor belt) can be caused by which of the following

Influx of freshwater

Which of the following is incorrect about Milankovitch Cycles?

It influences the Carbon cycle and other chemical cycles of Earth's system.

Climate ___________________ are biological, chemical, or physical signatures preserved in rocks, sediment, or ice records that indirectly indicate past climate conditions.

proxy indicators

Which of the following best describes a positive feedback for climate change associated with the carbon cycle?

Warming causes permafrost to thaw, releasing more CO2 and methane into the atmosphere.