Earth 154 Midterm Review

What are the three main "zones" of fluid flow and reaction in submarine hydrothermal systems?

1) Recharge Zone: where seawater enters the crust and percolates downward. 2) Reaction Zone: Where the reactions determine the final chemical characteristics of the hydrothermal fluid. 3) Upflow Zone: Where the hydrothermal fluids rise and are released at the seafloor.

What are the relative proportions of oceans versus continents on the Earth's surface?

70.8% of Earth's surface is covered by oceans, and 29.2% is covered by land (70-30 ratio).

What is a blow-out? What is a blow-out preventer: what does it do and how does it work? Why is this necessary?`

A blow out is when pressure and oil fluid escape the well you are drilling. A blowout preventer is a giant valve that prevents oil, gas, and excessive pressure from getting out. It cuts and seals the pipe. It is important, because it prevents explosions that could kill oil rig workers.

A. What are Back-arc basins? B. How do metal sulfide deposits at back-arc spreading ridges differ from those at mid-ocean ridges? (What metals are present in higher concentrations than in deposits at mid-ocean ridges to make these deposits more valuable?) C. Are these types of back-arc basin metal sulfide deposit a resource anywhere else? What metals are sought and were do these occur (name a country/countries or region)

A. Back-arc basins are seafloor spreading and metal sulfide deposits. They are associated with active margins and trenches. B. At back-arc spreading ridges, rocks are more metal-rich, and they have higher concentrations of gold than those at mid-ocean ridges. C. Yes; they are found in Canada. Specifically, the metals are copper, gold, zinc, and lead.

Where are Brazils's new offshore oil and gas fields (A. what ocean province, B. what kind of "trap"?)?

A. Brazil's new offshore oil and gas fields are on the continental slope, in a deep salt trade below the seafloor. B. They are found in pre-salt traps. These are underneath salt deposits, but they were previously unseen due to overlying salt.

A. Where is it currently planned to mine massive sulfide deposits at an oceanic spreading center (in a back-arc basin)? B. What are some features that make this specific site a good one for seafloor mining? C. How will this mining be carried out? (what equipment will be used?)

A. It is currently planned to mine massive sulfide deposits at an oceanic spreading center in New Guinea. B. Here, there are high lead, gold, copper, and zinc concentrations. Also, it is near land. C. This mining will be carried out with the help of support vessels, auxiliary miners to grind rock, and the gathering machine to vacuum and pump rock to the surface.

How does cold, basic seawater change into hydrothermal fluids? Specifically: A. What heats the fluid? B. What role does magnesium play in the composition of hydrothermal fluids? (what happens to magnesium, and how does this change the fluid?) C. How does the hydrothermal fluid get enriched in metals? (where do the metals come from?)

A. Magma chambers heat the fluid. B. At around 150 degrees Celsius, the magnesium precipitates out of the sea-water fluid, takes OH along with it (out of solution), and turns into acid. C. Once the fluid enters the reaction zone, the hot acid allows it to leach the metals from surrounding rock and sulfur from basement rocks in the deep "reaction zone."

A. What are manganese nodules? B. Where do they occur in the oceans? (What oceanic Province) How abundant are these? C. How do they form (2 main processes)?

A. Manganese nodules are deposits of metals with high metal concentrations. B. They occur on the seafloor of the ocean and are found mainly on abyssal plains, away from other sediment inputs. They cover up to 90% of the seafloor. They are very abundant. C. They form from either the hydrogenous process or diagenetic process.

Besides supply and demand affecting the price of oil... A) How does Technology affect the supply and price of oil? B) Give two examples of how technology has affected the supply and price of oil over the last 20 years.

A. New technology gives us access to oil that we couldn't get to before (ex: tar sands and fracking). B. Mining tar sands contains unconventional oil and refines it and creates fuel (which decreases price and demand). Fracking pumps fluid into the group to form cracks, which allows for the production of oil and gas.

What are some potential problems with: A. the technology and physical process of mining the seafloor, and B. the seafloor and oceanic environment resulting from seafloor mining?

A. One major problem with the technology and physical process of mining the seafloor is that it has never been done before. B. This has been found to kill organisms at its vents, turbidity is caused by this, and toxic metals are released into the water.

How do Petroleum deposits form? Specifically: A.What is the source of organic matter? B. how does this become petroleum: i. how is this chemically transformed, and ii. what two factors drive these reactions? C. How does it become gas?

A. Plankton and algae are the sources of organic matter. B. This becomes petroleum when thick accumulations of sediment and pressure cause the heating of buried sediments and maturation (hydrocarbons break into progressively smaller molecules) of organic matter to gas and oil. C. It becomes gas with a lot of time passing. Longer time and higher temperatures cause the cracking of hydrocarbons.

Where is this new oil field in Africa (A. what ocean province, B. what kind of "trap"?)?

A. The new oil field is found on the continental slope. B. It is on pre-salt deposits.

What are two problems that are unique to drilling in the Arctic: A. regarding the process of drilling; and B. potential environmental problems?

A. There are threats to drill rigs and equipment. There is damaging wildlife, as well. B. Environmentally, long winters would prevent spill cleanup, as oil can freeze in the ice. Also, the Arctic has a short growing season, which means it would take a long time for plants and animals to recover.

How much of the oil was recovered or cleaned up? What happened to the rest of the oil?

About 25% of the released oil was collected or removed, while the other 75% remains in the environment in one form or another.

What are two main ways that active and passive continental margins differ?

Active and passive continental margins differ based on their proximity to plate boundaries. Passive margins (no earthquakes) are often imbedded within the interior of lithospheric plates, while active margins (plate boundaries) are often marked by a high degree of tectonic activity.

In total, how much metal is present on the seafloor in metal sulfide deposits? How much of this is Copper plus Zinc? Assuming all this copper + zinc is copper, how much is this worth?

Approximately 600 million tons of metal is present on the seafloor in metal sulfide deposits. About 30 million tons is copper and zinc. This is worth about $200 billion.

What controls the overall depth of the ocean basins?

At mid-ocean ridges, new ocean crust is created, and as it gets older, it gets deeper, cools, and its density increases. (Age and density control the overall depth of the ocean basins.)

What happens at subduction zones? What major ocean province occurs here, and why?

At subduction zones, the oceanic crust usually sinks into the mantle, beneath lighter continental crust. It is at subduction zones where deep ocean trenches are. This is because one plate is constantly being pushed under another one.

What is present at the bottom of the Red Sea? How and why does this deposit differ from metal deposits at mid-ocean ridges out in the open-ocean? Who is interested in mining metal deposits in the Red Sea, and why?

At the bottom of the Red Sea, there is a huge ore deposit of 100 million tons. This differs from that at the mid-ocean ridges, because they run parallel along the middle of the Rea Sea. Saudi Arabia and Sudan are interested in mining metal deposits in the Red Sea, because it contains a large amount of zinc, silver, gold, and copper.

Who was at fault, the oil companies or the government?

BP was accused on nine faults, and the government did not enforce regulation. They were both at fault.

Besides hydrothermal vents, where else on mid-ocean ridges does microbial life (bacteria) occur?

Bacteria also live in the subsurface biosphere in volcanic rock, way beneath the seafloor (at mid-ocean ridges and ridge flanks). Here, it is a lot colder, and there is a blizzard of white debris.

What is bathymetry? What are two modern methods of measuring bathymetry over large areas?

Bathymetry is the measurement of ocean depths and the charting of the shape or topography of the ocean floor. Today, multi beam echo sounders and satellite bathymetry help measure bathymetry over large areas.

What is the concept of "Peak Oil?

Because oil is a limited resource, global oil production will reach a peak and then decline. This will cause prices to rapidly increase, causing economic hardships and chaos to many.

What equipment is needed for offshore drilling: think of what is required between the ship and the seafloor, at the seafloor, and beneath the seafloor.

Casing, cementing, a riser, and a blowout preventer are needed for offshore drilling.

What is the base of the food chain at hydrothermal vents on mid-ocean ridges? How could this be considered an ocean "resource"?

Chemosynthesis bacteria is the base of the food chain at hydrothermal vents on mid-ocean ridges. This is considered an ocean resource, because they are able to create their own organic compounds without photosynthesis, and they can support other lifestyles.

What are six ocean provinces? (be able to sketch these)

Continental shelf, continental slope, mid-ocean ridge, trench, abyssal plain, and continental rise are the six ocean provinces.

What geological features (or processes) are necessary to form a petroleum deposit or "Reservoir"?

Deep basins, thick sediment, source rock, organic matter, and a trap are necessary to form a petroleum deposit or reservoir.

How far offshore does state control of oil and gas go?

Each state owns territory that extends about three nautical miles from the shore and has complete control over this territory. Texas and the west coast of Florida are the two exceptions to this rule, as their territories expand nine nautical miles.

What are the two main processes that control the differences in the overall shape (bathymetry, volcanism, etc) of fast-spreading (like the East Pacific Rise) and slow-spreading (like the Mid-Atlantic Ridge) mid-ocean ridges? Which of these processes is associated with fast- and which with slow- speeding ridges?

Fast-spreading ridges have a robust magma supply (greater magma budget), whereas slow-spreading lava is induced more by the role of tectonics (faulting and fracturing) and tectonics.

How far offshore does Federal control of oil and gas (and everything) go?

Federal control of oil and gas extends around 200 nautical miles offshore (EEZ).

How do black smoker chimneys grow?

First, the hot fluid mixes with cold seawater, which contains sulfate and calcium. This results in the formation of anhydrite, which forms early chimneys. Second, it cools and mixes with seawater. Third, the metals precipitate as metal sulfide minerals.

The TAG hydrothermal metal sulfide deposit has black smoker vents, but it also has "white smoker" vents, with different fluid compositions. What do these white smoker fluids and the presence of anhydrite (CaSO4) deep within the TAG sulfide mound tell us about processes within the mound?

It tells us that cold seawater was mixed with hot hydrothermal fluids in the mound, which formed anhydrite and metal sulfides, within the mound.

What are some factors that determine how desirable different types of crude petroleum are?

Light crude oil is more desirable than heavy crude oil. This is because it is easier to get out of the ground, while heavy oil requires more refining and is harder to get out of the ground. Sweet oil requires a higher price than sour oil (which is a sulfur contaminant), because it has fewer environmental impacts associated with it. Light sweet crude is the best, and heavy sour crude is the worst.

What are two major negative effects of the BP oil spill on ocean resources?

Major negative effects of the BP oil spill on ocean resources are that it hurt people's health around the area, it decreased tourism to the area, it was bad for fishing, and the environment for the marine life was partially destroyed.

What are some arguments against Peak Oil?

New technologies will extract oil from low permeability reservoirs and tar sands. New oil deposits will be found offshore or in deeper waters. Other energy sources, such as wind, waves, and tides will develop.

How does North Sea production compare to the US Gulf Coast?

North Sea production is about equivalent to that of the US Gulf Coast's (1.5 million, which is 15% of US production).

In what oceanic "provinces" do Offshore Oil and Gas deposits occur? Why do they occur here, and not at mid-ocean ridges or on the abyssal plain?

Offshore oil and gas deposits occur on the continental shelf and slop in passive margins. This is because there is a lot of pressure and heat here, which help form oil and gas.

What is the general trend of exploration and production with respect to the coast and water depth?

Oil companies have extended exploration and production of oil farther and farther from the coast and deeper and deeper in the ocean now out to OSC and pre-salt deposits.

What are three ways oil spills can occur in the oceans?

Oil spills can be caused by equipment breaking down in the oceans, people making mistakes or being careless, natural disasters, or deliberate acts by countries at war.

What are three ways an oil spill affects marine life?

Oil spills damage the ocean floor, they can cause hypothermia in sea animals, they can cause deformities of the heart in tuna, and they can cause drowning.

What are some estimates of how much oil is at Brazil's new offshore oil and gas fields?

One estimate on how much oil is left there is 176 billion barrels worth. This is enough to supply the world's current oil needs for about five years.

What are some potential problems with mining manganese nodules on the seafloor?

One potential problem with mining manganese nodules on the seafloor is that is can be damaging to ecosystems, leading to the killing of organisms. Also, it can be very noisy, which would disturb nearby sea animals. It could also modify the environment for hundreds of years.

What is the problem with Petrobras and Brazilian government officials?

Petrobras is an oil company run by the Brazilian government, and government officials were taking bribes and companies were being overcharged. Petrobras officials colluded with cartels of campaniles to overcharge the oil company for construction and service work.

How do salt deposits form on continental margins? What role do salt deposits play in offshore oil and gas deposits?

Salt deposits form on continental margins as a result of the evaporation of seawater in restricted basins. They form traps for oil and gas reserves.

What kinds of deposits are being found and exploited (what kind of crude oil)?

Since all of the light crude oil has already been found, heavy crude is being found. However, it is less desirable, because it is harder to extract.

What events or problems caused the blowout on the Deepwater Horizon rig (BP, Gulf of Mexico)?

Some events or problems that caused the blowout on the Deepwater Horizon rig are problems with cementing, the rush for them to finish, they did not properly test the cement, they were behind schedule, and the blowout preventer failed.

What are the main features of submarine hydrothermal vent fluids? (i.e.: what are the main ways these fluids differ in temperature and composition from seawater?)

Some main features of submarine hydrothermal vent fluids include extremely high temperatures (350 degrees Celsius), low pH, high concentrations of metals, and no oxygen. In comparison to sea water, submarine hydrothermal vent fluids have higher temperatures, are more acidic, have higher metal concentrations, and have less oxygen.

What is going on to help increase exploration in the North Sea?

Tax breaks and incentives are being offered, to again increase its exploration.

What is the EEZ?

The EEZ is the exclusive economic zone. It is the 200 mile exploration zone given to each country. It gives the country rights in its zone to exclusively mine and fish.

What is the International Seabed Authority? What do they do?

The International Seabed Authority regulates seafloor leases outside of the EEZ.

How old is the TAG hydrothermal deposit? What does its cycle of activity and quiescence and the presence of breccias (broken rock cemented by different minerals) tell us about how the deposit formed?

The TAG hydrothermal deposit is about 20,000 years old (maybe older). It tells us that there have been numerous cycles of mound material constantly reworking, which means that there has been a long history of intermittent growth and inactivity.

At what type of mid-ocean ridge are the biggest metal sulfide deposits found (Fast-spreading or Slow-spreading?) Why do you think the biggest deposits are found here?

The biggest metal sulfide deposits are found at slow-spreading ridges, because it is here where it is not covered by lavas, so it takes more time for deposits and mounds to build up

What is the future of offshore oil and gas in the Arctic?

The future will most likely bring more efficient, useful equipment, which will help the economy, by creating more jobs in the Arctic.

What are three things about government regulation of offshore drilling today that are different because of the Deepwater Horizon blowout and spill?

The government upgraded standards on casing and cementing. Spill response equipment and drilling rigs have been advanced and more readily available.

What causes precipitation of metal sulfides in black smoker chimneys?

The mixture of hot vent fluids (which contains calcium) and cold seawater (which contains sulfate and calcium) causes the precipitation of metal sulfides in black smoker chimneys. (The cooling and mixing with seawater.)

In 6A and 6C pdf readings, Cyprus (in the eastern Mediterranean) is mentioned: What is the origin of these rocks in Cyprus? Why do we care about them in a class on Ocean Resources?

The origin of the rocks in Cyprus is Troodos Ophiolite. We care about them because they contain metal sulfide deposits, which are mined for copper.

What are three of the problems that Shell had with drilling in the Arctic?

The ship lost lower, ice floes forced the shutdown of two wells, and the testing for containment failed.

What is unique about the Arctic ocean that makes it desirable for offshore oil drilling (think where offshore oil deposits are)?

There are vast continental shelves. They hold about 22% of the Earth's oil and natural gas resources.

What is the dispute in the South China Sea? What is China doing to some coral reefs in this area? Why does China want this area (What valuable resources are there?)?

There is a dispute in the South China Sea, concerning territorial control between China and several Southeast Asian nations. China has seized small land formations or reefs, to make the islands large enough to support small military institutions. There are about 11 billion barrels of oil and 190 trillion cubic feet of natural gas in deposits under the South China Sea.

Are manganese nodules being mined or extracted from the seafloor? Why or why not? What is going on with exploration for manganese nodules, and who is doing this?

They are not being extracted from the seafloor. This is because extractors don't know the effects on the environment from doing this, and they don't have the correct technology to do this, although it is being developed. China, Germany, India, Japan, and Russia are some nations looking to explore for manganese.

What are the four main metals in hydrothermal vent fluids?

They are zinc, manganese, iron, and copper.

What valuable metals and other elements do manganese nodules contain that are of interest as a resource?

They contain nickel, copper, cobalt, and rare Earth elements.

Rivers bring dissolved material to the oceans. How do submarine hydrothermal systems influence the composition of the oceans in comparison to rivers? Which is more important?

They maintain the composition of the oceans and keep the chemistry as balanced as possible. They are equally important.

How do magnetic anomalies show the mechanism of seafloor spreading and continental drift?

They match magnetic time scales and show that crust is progressively younger toward mid-ocean ridges.

What common purpose do drilling mud (or drilling fluid), casing, blow-out preventer, and riser serve?

They prevent harmful substances from leaking or escaping and harming the environment. Also, they keep pressure under control.

What are three main differences in morphology between fast and slow spreading ridges?

Three main differences in morphology between fast and slow spreading ridges are that fast spreading ridges appear to be broader, smoother, and have an axial/high ridge. Slow spreading ridges tend to be steeper, rougher, and have an axial valley, similar to that of the Grand Canyon. Also, fast spreading ridges are associated with sheet plows, and slow spreading ridges are associated with pillow basalts.

What are 3 things that Petrochemicals used for?

Three things that petrochemicals can be used for are paints, fertilizers, and detergents.

The TAG metal sulfide deposit is 3 million metric tons, and contains 5% Copper. How much is this deposit worth?

Today, this is worth $1,000,500,000 (one billion hive hundred dollars).

What are some other organisms at hydrothermal vents? How are these related to bacteria?

Tube worms, shrimp, and clams are three other organisms at hydrothermal vents. Tube worms and clams both have symbiotic relationships with bacteria, as bacteria live inside tube worms and bacteria provide nutrients for the clams. Shrimp and clams eat bacteria, as well.

What are two ways BP tried to stop the leak?

Two ways in which BP tried to stop the leak are by adding a containment dome and a well-head to pump mud.

Has US Oil Production Peaked yet? What are the trends? Has global production Peaked? What is the overall trend? How does offshore oil affect "Peak Oil"?

US oil production has peaked, but new technology, known as fracking, has caused US production to rebound and continue to increase. US average annual production first peaked in 1970 at 9.6 million barrels per day. Global production has not peaked yet. It has steadily increased over the past 50 years. Offshore oil affects peak oil by offsetting the peak to a later date and slowing the decline in its production.

What happens with offshore drilling policy in the US when a new president is elected? What is going on now with offshore drilling policy in the US?

When a new president is elected, he has the power to do whatever he wants regarding offshore drilling. For example, Trump has lifted bans on drilling that were in place by Obama.

Is this (in Africa) similar to the new finds offshore Brazil, and if so, why?

Yes, because they formed in the same narrow basin during initial rifting of the continents.

Has North Sea production "peaked"?

Yes. North Sea production peaked in 1999/2000, at 6 million barrels per day.