Geo. Exam 3

1. What are the 2 evaporite depositional patterns? How do they differ? 2. What is a sabkha? What minerals occur there? 3. Where do many ancient evaporate deposits come from?\ 4. What kind of structure does a anhydrite tend to have?

1. A Bulls eye pattern (typical of closed basins, where soluble salt in the center) and a tear drop pattern (typical of open basins, where soluble salt occur away from basin opening). Note: Both patterns have a layer of halite, followed by gypsum, and then calcite. 2. Sabkha is a salt fat where evaporates form in inter-tidal zones ((i.e where high tide covers and low tide does not). Minerals occurring are Gypsum, Dolomite, and Anhydrite. 3. Shallow shelves and basins 4. a chicken wire structure

1. What is a conglomerate? 2. Is it a mature sed. rock? 3. What is the only force that could cause sediment to form conglomerate?

1. A clastic sed. rock, formed by cemented rounded grains of gravel. Note: its roundness indicates transportation 2. No, it has no quartz and is not sorted. 3. Strong water current (b/c it carries a long distance and makes gravel rounded). Note: Conglomerates indicate a fluvial environment (i.e river).

1. What is Shale? Where do you find it? 2. What difference between shale and claystone? 3. How are shales grains arranged? 4. What is fissility?

1. A clastic sedimentary rock formed by cemented grains of clay only. You find it in quiet environments ( lakes, lagoons, on land, etc). 2. Shale is compressed claystone. Because of compaction during lithification, the flat crystals of clay acquire an orientation perpendicular to the direction of compression. 3. Their arranged so that shale can be split along flat surfaces, called fissile 4. a characteristic alignment of shale in which the grains are visible at the macroscopic scale.

1. What is Siltstone? 2. What is silt primarily composed of? What type of environment would you find it in? 3. What is Mudstone? What is Claystone? What environment would you find it in? 4. Why are mudstone and claystone rare to find?

1. A clastic sedimentary rock formed by cemented grains of silt 2. Its primarily composed of quartz and you would find it in a low energy environment (ex. swamp, lake, lagoon, etc) 3. Mud stone is aclasticsedimentaryrockformedby cemented grains of silt and clay (mud). Claystone is a clastic sedimentary rock formed by cemented grains of clay only. Low would find both in very quiet environments of deposition. 4. Their flat clay minerals have not been subjected to compaction and they retain a random crystal orientation even upon cementation.

1. What is Breccia? 2. Is breccia round or sorted? What does that tell us? 3. Where is it usually found?

1. A clastic sedimentary rock, formed by cemented angular grains of gravel 2. No, it is neither rounded or sorted. This shows there was no transportation in it's creation. 3. In mountain areas or along faults.

1. What is a sandstone? 2. What kind of environment does there presence indicate? 3. What are 3 ways in which sandstone types differ? 4. What 2 factors determine the color of a sandstone?

1. A clastic stone, formed by cemented grains of sand. 2. A high energy environment 3. In roundness, sorting, and compositional maturity. 4. Its constituent minerals and its cement.

1. What builds coral reefs? Are reefs the same throughout time? 2. What are the best ocean conditions for coral reefs? 3. Are all reef made of coral? 4. What are algal mats?

1. A community of calcite secreting organisms, such as polyps and algae. No they change as organisms communites change. 2. Warm tropical waters that are far from sources of sediment. 3. No, Some can be made of algae or sediment. 4. mats of cyanobacteria that collect sediment on the seafloor and create stromatolites.

1. What are Evaporates? 2. What promotes brine to form? 3.What are the two most common ions in evaporates? 4. What are the 3 most common minerals in evaporates?

1. A type of chemical sedimentary that from the evaporation of brine (i.e. salt rich water) 2. Hot temperature and lack of precipitation. These would be areas with hot weather and low rain fall. 3. Na and Cl. Note: this is because they last long in water 4. Halite, Gypsum, and Anhydrite.

1. What is Coquina? What type of environment does it form in? 2. Whats the difference between Micrite and Chert? What does there presence generally indicate? 3. What are the main contributors to the formation of Micrite and Chert? 4. What is a other calcite deposit sed. rocks we learned are in deep-ocean? What are 2 other silica deposit sed. rocks?

1. A type of limestone formed almost entirely of sorted and cemented fossil debris, most commonly coarse shells and shell fragments. It forms in high energy environments. 2. Micrite are chemical sed. rocks made of calcite and chert chemical sed. rocks made of silica. There presence indicates a once deep-marine environment. 3. Microscopic organisms in the ocean that make a shell (or test) of calcite or silica. 4. Chalk is Calcite deposit. Diatomite and Radiolarite are Silica deposit.

1. What are the 2 main iron-rich sed. rocks we discussed in class? Describe each and tell when and how their formation process happened. 2. Iron-rich black shale contain a lot of what mineral? 3. What iron- rich mineral might you find scatter on the ocean floor? 4. What happens to Iron rich materials when their put in the ocean?

1. A. Banded Iron Formations (BIF's): Alternating bands of grey chert and red iron-rich minerals. Texture shows that that iron is transported in solution instead of as a precipitate which shows they formed in Precambrian atmosphere, when there was no oxygen B. Phanerozoic Ironstone: Mudstones with high Iron content. Black coloration shows it formed during green house time (Note: Black= no oxygen) by the erosion and deposition of laterites (i.e. red soil) 2. Pyrite 3. Manganese nodules (nod-jewels) 4.iron-rich materials crystallize, grow together, and settle to the ocean bottom.

1. What are the 4 chemical sedimentary rock groups that result from biological activity that we discussed in class? 2. Where are 3 places that phosphate ions naturally originate from? 3. Where do we commonly find phosphate ions? 4. What are nodules and how do they contribute to phosphorite deposits?

1. A. Carbonates B. Chert C. Phosphates D. Organic-rich materials (ex. coal and petroleum 2. A.hydrothermal deposits (i.e. natural springs) B. weathering of fluorapatite. C. Leaching of phosphate-rich materials, like guano 3. In vertebrate bones and teeth. Note: Phosphate deposits from sedimentary rocks are very rare. 4. Nodules are piles of organic matter along the edge of continental shelves that are created from fish remains. The bones of those fish turn into phosphorite deposits

1. List the 3 properties of clay minerals that we discussed in class. 2. Do clay minerals have a charge? 3. Define soil and what it is typically composed of.

1. A. Clay minerals are always flat B. Clay minerals absorb both water and positively charged ions. C. Water does not circulate through clay minerals. Note: This explains why mud does not flow, it just swells up as water is absorbed by the clay. 2. Yes, they are negatively charged and attract positively charged particles (i.e. water and ions) 3. Soil is a layer of weathered material on top of bedrock (i.e. solid rock underground). Its typically composed of: Clay Minerals, Quartz, Water, and Organic Matter.

1. What type of sediment (coarse or fine?) you would find in each environments listed ( Hint: Is it a low energy or high energy environment): A. Deep ocean? B. Swamps? C. River? D. Delta/floodplain? E. Alluvial fan (i.e. sediment covered base of mountain chain)? F. Lake?

1. A. Fine B. Fine C. Coarse D. Fine E. Coarse F. Fine

1. Name and define the 4 components (i.e. parts) of sediment. 2. What is porosity? How does cement effect porosity? 3. What does the presence of matrix mean? 4. What does a fracture in a sed. rock create?

1. A. Grains: The framework of sed. rocks B. Pores: Empty space between grains that are reduced in size from compaction and fill with cement. C. Cement: Any chemical precipitate that attaches grains to one another. D. Matrix: Sediment that is smaller than a dominant sediment and fills the pores of that dominant sediment. 2. Porosity is the ratio of percentage of pore volume to percentage of rock volume. The more cement, the lower the porosity or a sed. rock. 3. A sed. rock is unsorted. Note: Vice versa, if a sed. rock does not have matrix, it is sorted. 4. New pores and a second porosity for the rock.

1. Physical weathering breaks down rocks into fragments. What are the 4 types of fragments that result from physical weathering? What are the sizes that distinguish each? 2. What stays the same in physical weathering? What changes? 3. What is the difference between clay minerals and clay particles 4. Whats the difference between how a high energy environment and a low energy environment affect physical weathering fragments?

1. A. Gravel (>2mm) B. Sand( between 2mm and 1/16mm) C. Silt (between 1/16mm and 1/256 mm) D. Clay (<1/256mm) 2. Volume of the rock stays the same, but surface area changes. 3. Clay particles are the result of physical weather and depend on size. Clay minerals are the result of chemical weathering and depend on composition. Note: All clay minerals are clay particles, but not all clay particles are minerals 4. High energy environments erode and transport gravel and sand. Low energy environments erode and transport silt and clay.

1. What are the 2 ways in which calcite can form? 2. What conditions in water dissolve calcite? What precipitates calcite? 3. How can Limestone form?

1. A. Inorganically: Forming in water due to changing chemical equilibrium B.Biochemically/ Bio-clasticaly: Forming due to the activity of organisms (Biochemical) and weathering of organism remains (i.e. Bioclastic) . 2. High Pressures and Low temps create carbonic acid and dissolve calcite. Low pressure and High temps release CO2 and precipitate calcite. 3. Both ways, inorganically and through biological activity.

1. Name the 3 categories of organism in the ocean that we listed in class. 2. What are 2 types of plankton and 2 examples of each that we learned in class? Include what test they secrete, the ooze they make, and the rocks their ooze produces

1. A. Nekton: Swimmers (ex. Fish, Dolphin, etc.) B. Benthos: Bottom dwellers (ex. Crabs, sea lilies, etc.) C. Plankton: Floaters 2. A. Phytoplankton (plant-like) -Diatoms: Silica shells, siliceous ooze, and make diatomaceous earth and radiolarites (Cherts) -Coccolithophorids (coco- litho-for- ids): Calcite shells, calcareous ooze and create chalk B. Zooplankton (Animal-like) -Foraminifera (For-men-nif- era): Calcite shell, calcareous ooze and makes micrite -Radiolarians: Silica shell, siliceous ooze, and make diatomaceous earth and radiolarites

1. What are 3 process that Bio. sediment depends on. 2. What is calcite compensation depth (CCD)? 3. What is Lysocline? 4. What preserves calcite past CCD?

1. A. Productivity: there must be enough plankton. Note: this depends on food and light. B. Destruction: Enough shell must be made so that not all of the shells secreted are dissolved C. Dilution: There cannot be other sediment around, they dilute the ooze. 2. The depth where calcite completely dissolves in deep-sea, which is about 4.5 km. Note: Shallower than CCD= Calcite does not dissolve, Deeper than CCD= Calcite dissolves 3. The depth at which calcite begins to dissolve rapidly 4. Either mud on the abyssal plain or siliceous ooze

1. Name and describe the 3 sediment bi-products of Feldspars and micas being changed by chemical weathering. 2. What sedimentary rock do these each of the 3 sediments generally form? 3. Why does Quartz (SiO2) not chemically weather down?

1. A. Quartz: becomes a round particle the size of sand B. Clay Minerals: a flat crystals because its made up of sheet silicates and the size of clay (i.e. very small) C. Ions in solution: Dissolve in water and can precipitate salts. 2. A. Quartz form sandstone B. Clay minerals form shale C. Ions in solution will form limestone 3. SiO2 is held together by covalent bonds which are relatively strong and cannot be broken down by an acid.

1. Name and describe the formation of the 3 types of inorganic limestone. 2. Do most carbonates form on the land or in the ocean? 3. What are fossiliferous limestone and where do they form?

1. A. Travertine: precipitated calcite formed directly from water upon loss of CO2. Found near land in waterfalls, springs caves and caverns B. Tufa: A less dense form of Travertine. Found also near land in playa lakes C. Oolites: Limestone formed of tiny precipitated calcite balls called ooids. Found in shallow seawater and shelfs. 2. In the ocean. 3. A type of limestone, made mostly of CaCO3 (as calcite or aragonite) that contains an abundance of fossils or fossil traces. They form in shallow ocean (ex. lagoons, bays, etc)

1. What are Carbonates? What are the two most common carbonate minerals? What are the two most common carbonate rocks? 2. Do carbonates always remain the same?

1. Chemical sed. rocks composed of the carbonate minerals (i.e. minerals with carbonate in there composition). Most common carbonate minerals are calcite and dolomite. The most common carbonate rocks are Limestone and Dolostone. 2. No, they change throughout out geological time. Note: Dolomite is a form of slow altered calcite.

1. How are graded beds organized? What another name for them? 2. Describe continental rise. 3. What does the continental rise mark?

1. Coarse grains on bottom and fine grains on top. This is also known as the "Bouma Sequence". (Bow-ma) 2. Continental rise occurs when turbidites from turbidity currents conglomerate to form a abyssal fan at the bottom of the continents slope . As the abyssal fan grows larger and larger from increasing sediment, a continental rise is formed 3. It marks the transition between the slope and the abyssal plain of the deep ocean.

1. What is true of grains that are floating in matrix (i.e. "popping out" slightly)? What about grains that are in direct contact (i.e. completely surrounded by matrix)? 2. What are 2 differences between roundness and sphericity? 3. Which rounds quicker: coarse grains or fine grains?

1. Grains floating in matrix are supported by the matrix. Grains that are in direct contact are framework/grain supported 2. Roundness is refers to how smooth the rock is and sphericity is about how spherical it looks. Additionally Roundness depends on the distance transported and sphericity depends on how a grain originally broke off. Note: Even an angular grain can be spherical. 3. Coarse grains

1. What are two pieces of evidence that show how much a sediment has been transported? 2. What can we infer if a clastic rock has large grains? 3. What does a sorted texture mean?

1. How small the sediment is and how round (or smooth) it is (i.e. as distance increases, size decreases and roundness increases). 2. That the rock is not far from its producer because the sediment has not traveled far. 3. That the sedimentary rock is made up of sediment that are more or less the same size.

1. Where can petroleum be found? 2. What can stop petroleum from hitting the surface? 3. What are two states of petroleum?

1. In the pores of sandstone and limestone. Note: Petroleum forms in source rocks, which are mostly fine-grained, deep marine ones 2. Natural structural or stratigraphic traps. 3. Gas (ex. methane) and Liquid (oil)

1. What 3 things happen over time as a sediment garners more distance from its source? 2. What are the requirements of a sediment to be mature? 3. What types of sediments are mature and what are not? Why are they not? 4. Whats the only sediment that has levels of maturity?

1. It becomes more rounded (i.e. smooth), sorted, and rich in quartz. 2. It must be rounded, sorted and rich in quartz 3. A. Gravel is never mature, because it contains small grains of sand, clay and/or silt. B. Silt is always mature C. Clay is never mature, because its always flat and cannot be weathered D. Sand can be mature but not always. 4. Sand

1. What happens as clay stone is compressed? 2. Why are Shales generally darker? How did black shale come about? 3. List the 7 clastic rocks we discussed in class.

1. It losses water and forms into shale. 2. Shales are usually dark because of their high content in organic matter. Black shale came about on the earths oceanic crust during greenhouse time (i.e before oxygen was abundant) and organic matter settled on the sea floor. 3. A. Breccia B. Conglomerate C. Sandstone (Quartz sanstone, Arkose Sandstone, and Graywacke Sandstone) D. Siltstone E. Mudstone F. Claystone G. Shale

1. Why does magnesium deform calcite but not dolomite? 2. Whats the differnce between calcite and aragonite (i.e. its polymorph)? 3. What 4 ocean conditions are preferable for dolomite?

1. Magnesium disturbs the calcium ions in calcite but, Mg forms its own separated sheets in dolomite. 2. They different structurally. Note: Most marine life prefer aragonite to live in because it is not affected by Mg in the water like calcite is. 3. A. High salinity B. High pH C. Low Ca/Mg ratio D. High temperature

1. Are coal and petroleum a sedimentary rocks? 2. What is coal made of? What are coal seams? 3. Whats the ideal environment to find coal in?

1. No, they are fossil fuels and consist of undecayed organic tissue that are burned to produce thermal energy 2. Coal is made of an accumulation undecayed plant material called peat . Coal seams are layers of coal between sedimentary rock. 3. Moist, tropical environments where there is a lot of plant vegetation

1. Where do the greatest amount of deposits generally accumulate? Explain 2. What are the 3 steps of lithification? 3. When is pore space in sediment reduced? 4. What is the most common cement for sedimentary rocks?

1. On continental margins, specifically on shelfs and continental rises (i.e. build up of sediment at the bottom of slope). This is because that is where water flows the slowest and gives particles a chance to settle. 2. A. Burial B. Compaction (i.e. compressed by layers of sediment above) C. Cementation (i.e. ions in water recrystallizing and holding sediment together) 3. During compaction 4. Silica

Name the 3 different types of Sandstone we discussed in class and how they differ (what there made of, what they're presence indicates, and where there found).

1. Quartz Sandstone: - Only mature sandstone - Indicates long distance transportation - Found at beaches and passive continental margins (i.e continent and ocean meet but not at plate boundary) 2. Arkose Sandstone: - Immature - Can be sub-angular or sub-rounded - Generally contains K-fledspar, and therefore does has limited transport. -Found at Alluvial fans (i.e. sediment covered base of mountain chain) and near active continental margin (i.e. continent and ocean meet at boundary) 3. Graywacke Sandstone: - Immature - A sandstone with a matrix (i.e. made of sand and mud). - Dark in color from carbonized organic matter - Organized in graded bed sequence (i.e coarse to fine grained sequence) - Found on continental slopes.

1. What rock can hold substantial amounts of oil? Does this have more or less oil than in sandstone and limestone? 2. Asphalt and Bitumens (mineral waxes) are examples of what? 3. How do iron-rich sed. rocks and evaporites form? Do these groups make up a large amount of sed. rocks?

1. Shale, creating oil shales. It has more oil than sandstone and limestone. Note: Oil shale is mostly from the Phanerozoic era 2. Forms of petroleum 3. They form from the ions being released from weathered, preexisting rocks and minerals. These ion precipitate into sed rocks. These groups do not make up much of sed. rocks (only 2%)

1. What is a carbonate factory? 2. Describe a coral reef and a stromatolites. 3. How are coral reefs built?

1. Shallow tropical water where there is a significant amount of carbonate deposit. Note: These deposits generally are limestone with fossil shell 2. A. Coral reef: A carbonate structures that occur in shallow, warm, and crystal-clear water. B. Stromatolites: Bottom dwelling carbonate structures composed of fine layers of carbonate that are produced by cyanobacteria in warm, shallow waters with high salinity. 3. They are build up by calcium carbonate secreting organism and overlap the remains of old coral reefs that can rise above the seafloor.

1. What can the sorting of a rock indicate? 2. What does poor sorting generally signify? What about better sorting?

1. The effectiveness of the mediums (such as water, ice, or wind) ability to separate grains 2. Poor sorting signifies that limited transportation occurred. Better sorting signifies a greater distance of transportation occurred.

1. What does a rounded quartz imply? 2. Which generally has more rounded grains: beach/desert sediment or glacier/river sediment? 3. What does a sed. rocks fabric refer to?

1. The quartz has been through many cycles of erosion, transportation, and deposition. 2. Beach and Desert sediment. 3. Fabric refers to the grain alignment in a sed. rock

1. What does the presence of K-felspar in a mineral imply? 2. What is a turbidity current? What sed. rocks do these form? 3. What is a Submarine Canyon? 4. What are turbidites?

1. The rock is not far from its sediment source, K-feldspar has limited travel. 2. A turbidity current is a current made up of sediment and water that flows down the slope of a sea or lake. These form Graywacke Sandstones. 3. A underwater canyon created from the power of turbidity currents 4. Deposits from turbidity currents that form layers of graywacke sandstone and mud in graded beds (i.e coarse on bottom and fine on top)

1. Are carbonates, silica, and calcium more common in rivers or sea water? What about Iron? 2. There are two forms of Ionic iron: Ferrous(Fe2+) and Ferric( Fe3+). Which is more soluble? What happens to ferrous iron once its oxides? 3. Is it common for sedimentary rocks to contain iron? How much Iron must a sed. rock in order to be considered Iron- rich? 4. What are the 3 most common sed. rocks?

1. They are more common in rivers. Iron is not common in either oceans or rivers. 2. Ferrous is more soluble. When ferrous iron is oxides it turns into ferric which bonds with oxygen to form hematite. 3. Yes, almost all sed. rocks contain iron. A sed. rock must be 15% Iron to be iron-rich 4. Limestone, Sandstone, and Shale

1. Why are evaporates not common today? When were they most common? 2. Name and describe the formation of the 3 types of evaporates.

1. They need certain settings, arid climate, and must be separate from other sediments (ex. clastic, carbonates). They were most common in Cambrian, Permian and Triassic periods 2. A. Non-marine evaporates (or playa-lakes): Deposits formed in closed lakes (i.e. do not go to the ocean) in arid regions. B. Shallow marine evaporates: Deposits form in supra-tidal (i.e. splashed area above the tide zone) and inter-tidal zones (i.e where high tide covers and low tide does not) C. Deep-marine evaporates: Form after several cycle of sedimentation (i.e. flooding and drying) as gravel sized blocks

1. What happens to ions in solution that are in pores and run out of water? 2. What is the only rock not formed by crystals? 3. What does lithification imply?

1. they recrystallize and form chemical sedimentary rocks. 2. Clastic rocks; they're formed by rock fragments. 3. A clastic sediment is turned into a clastic rock.