Midterm 2 Flashcards

Question

Describe the Fungi kingdom and provide examples of organisms in this kingdom

Answer 1

Eukaryotic cells; multi-celled, major decomposers and nutrient recyclers e.g. fungi, yeast, mold

Answer 2

Eukaryotic cells; multi-celled, obtain nutrients by photosynthesis e.g. trees, grass, plants

Answer 3

Eukaryotic cells; multi-celled, obtain nutrients by ingestion of preformed organic molecules e.g worms. clams, mammals, fish, sponges, reptiles, birds, ampibians

Answer 4

– The oldest known eukaryote fossils are in 1.2 Ga Mesoproterozoic rocks in Canada • The tiny organisms, called Bangiomorpha, were multicelled, probably produced sexually, and resembled red algae. • cells larger than 60 microns were abundant by at least 1.4 Ga. – The oldest known megafossil (i.e. not a microfossil) is Grypania, which is found in the 2.1 Ga Negaunee Iron Formation of Michigan. • Grypania may have been a large single-celled bacterium or algae. - Hollow fossils known as acritarchs were probably cysts of planktonic algae. They became common during the Meso- and Neoproterozoic.

Answer 5

– Eukaryotic cells probably evolved from prokaryotic cells that formed symbiotic relationships. – The organisms became unable to live independently. – Endosymbiosis - when one symbiotic organism lives within the other. – Endosymbiosis is seen in living eukaryotic cells that contain internal structures, or organelles, such as mitochondria and plastids. – The organelles have their own genetic material and they synthesize proteins just like prokaryotic cells. – Through organelles, bacteria could have entered into symbiotic relationships, eventually giving rise to eukaryotic cells.

Answer 6

– In multicelled organisms, cells are specialized to perform certain functions, such as reproduction and respiration. – Multicelled organisms first appeared in the Neoproterozoic. – The fossil record does not provide much information on the origin of multicelled organisms. – Most information comes from studying modern organisms. – Multicelled organisms with as few as four identical cells are capable of living. – Cells in colonies could evolve specializations, such as sponges. – Carbonaceous impressions of multicelled Proterozoic algae are known from many locations.

Answer 7

• Multicelled organisms live longer than single-celled organisms. • Cells can be replaced and new cells produced. • Cells have increased functional efficiency when their functions are specialized in organs.

Answer 8

1. Ediacaran fauna of South Australia • Soft body impressions. • Algae and several animals unknown today. • Fossils of three phyla may be present - jellyfish and sea pens (phylum Cnidaria), segmented worms (phylum Annelida), and primitive members of the phylum Arthropoda (which include today's insects, spiders and crabs). • Spriggina could be an ancestor of trilobites. • Possible early echinoderms. Ediacaran fauna is also a collective term for fossil associations similar to those found in South Australia • Found on all continents except Antarctica. • 545 to 600 mya fauna in Namibia, Africa and Newfoundland, Canada. 2. Other fossils • Jellyfish-like impressions. • Burrows probably from worms. • Possible 700-900 mya fossil worms from China. • Small branching tubes in 590-600 mya rocks from China could be early relatives of corals. • Neoproterozoic Kimberella, possible mollusk. • Several animals with skeletons, or at least partial skeletons, existed in the latest Neoproterozoic

Answer 9

• Most of world's iron comes from Proterozoic banded iron formations, especially those in Canada and the US. • Nickel and platinum from Sudbury mine, Canada. • Platinum and chromium from Bushveld Complex of South Africa. • Recoverable oil and gas from Proterozoic rocks in China and Russia. • Some Proterozoic pegmatites contain gemstones, tin, cesium, rubidium, lithium and beryllium. • Pegmatites adjacent to Harney Peak Granite in the Black Hills, South Dakota, are 1.7 Ga. They contain some of the largest crystals in the world and have been mined for gemstones, tin, lithium and micas.

Answer 10

- Cambrian - Ordovician - Silurian

Answer 11

• The supercontinent Pannotia (late Neoproterozoic Eon) began to break apart 550 Ma or shortly before the beginning of the Paleozoic Era at 541 Ma. • By the early Paleozoic, there were six major continents: Baltica, China, Gondwana, Kazakstania, Laurentia and Siberia.

Answer 12

• Each continent consisted of two major components: – 1. relatively stable craton over which epeiric seas transgressed and regressed. – 2. surrounded by elongated mobile belts in which mountain building took place. • North America: – Franklinian, Cordilleran, Ouachita, and Appalachian mobile belts.

Answer 13

• Geologists construct paleogeographic maps by looking at relevant paleoclimatic, paleomagnetic, fossil, stratigraphic, sedimentologic, and tectonic data. • The maps show land and sea distributions, possible climatic regimes, mountain ranges, swamps, and any glaciers.

Answer 14

• Paleozoic paleogeographic history is not as precisely known as the histories of the Mesozoic and Cenozoic Eras. • The magnetic anomaly patterns in Paleozoic ocean crust were largely destroyed by subduction during the formation of Pangaea (late Paleozoic). • Paleozoic paleogeographic reconstructions are primarily based on structural relationships, climate-sensitive sedimentary rocks (such as: red beds, evaporites, tillites, and coals), and fossil distributions.

Answer 15

– Baltica - Russia west of the Ural Mountains and most of northern Europe (Fennoscandia). – China - also includes Indochina and Malay Peninsula. – Gondwana - Africa, Antarctica, Australia, Florida, India, Madagascar, and parts of the Middle East and southern Europe. – Kazakhstania - Kazakhstan in Asia. – Laurentia - most of North America, Greenland, northwestern Ireland, and Scotland. – Siberia - Russia east of the Ural Mountains, Asia north of Kazakhstan, and south of Mongolia.

Answer 16

– Avalonia - Belgium, northern France, England, Wales, part of Ireland, Maritime Provinces and Newfoundland of Canada, and parts of New England, USA. – Various (volcanic) island arcs on microplates.

Answer 17

• Polar regions mostly ice free. – Recall: Neoproterozoic snowball earth • By Late Cambrian epeiric seas (epicontinental seas) covered parts of the continents. • Highlands in northeastern Gondwana, eastern Siberia, and central Kazakhstania. • Eastern Laurentia is a passive continental margin.

Answer 18

• Gondwana moved southward and crossed the South Pole. • Ordovician glaciations - tillites found in North Africa. • Early Ordovician - Avalonia rifted from Gondwana and moved northeastward. • Late Ordovician and Early Silurian - Avalonia collides with Baltica • Eastern margin of Laurentia becomes an active convergent boundary - subduction. • Taconic orogeny (mountain building) occurred in New England in the Late Ordovician.

Answer 19

• Baltica-Avalonia collides with Laurentia, which closes the northern Iapetus Ocean and begins the Caledonian orogeny on these continents. • Southern Iapetus Ocean remains open between Laurentia and Baltica-Avalonia. • Siberia and Kazakhstania moved from a southern tropical position in the Cambrian to a northern temperate latitude by the end of the Silurian.

Answer 20

large-scale (greater than supergroup) lithostratigraphic unit representing a major transgressive-regressive cycle bounded by craton-wide unconformities. • Sedimentary rock record of North America is divided into six cratonic sequences.

Answer 21

• The transgressive phase is usually covered by well-preserved younger sedimentary rocks. • The regressive phase ends with an unconformity – due to regional erosion. • Each of the six unconformities extend across various sedimentary basins of the North American craton and into mobile belts along the cratonic margin. • The basic unit of sequence stratigraphy is the sequence, which is a succession of sedimentary rocks bounded by unconformities and equivalent conformable strata. • Sequence boundaries result from a drop in relative sea level. • Sequence stratigraphy is used for correlation and mapping in the petroleum industry.

Answer 22

• Neoproterozoic – Early Ordovician. • Sediments of the first major transgression onto the Paleozoic North American continent. • Deposition of marine sediments limited to passive shelf areas of the Appalachian and Cordilleran borders of the craton. • Tropical climate (i.e. HOT) and erosion of the exposed craton. – No land plants until Ordovician • Transgressive phase of the Sauk Sea began in the Middle Cambrian. • By Late Cambrian, epeiric seas (shallow continental seas) covered most of North America, leaving only the craton (Canadian Shield) and a few islands of the Transcontinental Arch above sea level. • Shallow marine sediments accumulated on both the shelf and craton. Sediments included carbonates and detrital sands. • Carbonate deposition was dominant on the craton as the Sauk transgression continued during the Early Ordovician. • The advancing Sauk Sea eventually covered the islands of the Transcontinental Arch. • The Sauk Sea regressed from the craton of North America during the Early Ordovician, exposing land to erosion. • The exposed carbonates experienced extensive erosion in the tropical environment. • The resulting unconformity is the boundary between the Sauk and Tippecanoe sequences.

Answer 23

– In a stable marine environment where sea level remains the same, coarse detrital materials deposit near shore and fine-grained carbonates accumulate farthest offshore and away from the source of detrital sediments. – Cambrian rocks of the Grand Canyon, Arizona, provide an excellent model of marine sediment deposition during a transgression. – The Grand Canyon represented a passive shelf on the western margin of the craton during the time of the Sauk Sequence. – During the Neoproterozoic and Early Cambrian, the region was mostly above sea level. – The Tapeats Sandstone represents the basal transgressive shoreline deposits during the Early Cambrian. – As the transgression continued into the Middle Cambrian, the muds of the Bright Angel Shale were deposited on top of the Tapeats sands. – By Late Cambrian, the Sauk Sea transgressed so far over the craton in the Grand Canyon region that carbonates of the Muav Limestone were deposited over the muds of the Bright Angel Shale. – The vertical succession of Tapeats Sandstone to the Muav Limestone forms a typical trangressive sequence and represents a progressive migration of offshore facies towards the craton over time. – The Cambrian rocks of the Grand Canyon also illustrate that many formations are timetransgressive; that is, their age is not the same everywhere they are found. – Predictable succession of facies was deposited laterally at the same time – The Muav Limestone began to accumulate on the shelf before the deposition of the Tapeats Sandstone was completed on the craton. – The Bright Angel Shale is Early Cambrian in California and Middle Cambrian at the Grand Canyon. – Implication is that formations defined based on their lithostratigraphy are diachronous (Greek = through time), deposited at a different time in different places

Answer 24

• Middle Ordovician to Early Devonian • The Tippecanoe Sequence resulted from the transgression of the Tippecanoe Sea onto the North American craton following the post-Sauk regression. • The sea deposited clean and well-sorted quartz sands over much of the craton. • The Tippecanoe basal sandstones were followed by the deposition of carbonates as the transgression proceeded. • The limestones primarily resulted from growth of calcium-carbonate secreting organisms, such as corals, brachiopods, stromatoporoids, and bryozoans. • (dolostones resulted from magnesium-rich fluids altering buried limestones during diagenesis) • In the eastern portion of the North American craton, carbonates grade laterally into shales. • The shales represent the farthest extent of detrital sediments derived from the weathering and erosion of the Taconic Highlands. • The highlands resulted from a tectonic event occurring in the Appalachian mobile belt (Taconic Orogeny). • The Tippecanoe Sea gradually regressed from the craton during the Late Silurian. • Evaporites precipitated in the warm climates of the Appalachian, Ohio, and Michigan basins. • Nearly one-half of the sediments in the Michigan Basin are halite and anhydrite (post-depositionally-dehydrated gypsum). • The End of the Tippecanoe Sequence – The Tippecanoe Sea retreated to the craton margin by the Early Devonian. – Lowland topography was exposed. – The craton experienced mild deformation during the Early Devonian, which formed many domes and arches – uplifted areas on the craton; and basins – down-dropped areas on the craton that accumulated sediments.

Answer 25

– Organic reefs are limestone structures constructed by living organisms. – The first skeletal reef builders were the archaeocyathids of the Cambrian. – Coral and stromatoporoid reefs became common in the Middle Ordovician. – Reef and evaporite deposits are abundant in the Middle Silurian rocks of the modern Great Lakes region. – The Michigan Basin is surrounded by large Silurian barrier reefs.

Answer 26

– Reef and evaporite deposits are abundant in the Middle Silurian rocks of the modern Great Lakes region. – The Michigan Basin is surrounded by large Silurian barrier reefs. – The reefs restricted seawater circulation into the basin, which allowed for the precipitation of evaporites, including anhydrite (postdepositionally- dehydrated gypsum) and rock salt (halite). • In general, evaporite salts precipitate from seawater in a specific order, beginning with the least water-soluble and ending with the most soluble. • Calcite (CaCO3) precipitates first, then gypsum (CaSO4•2H2O) and finally halite (NaCl). After burial, gypsum dehydrates to anhydrite (CaSO4). • Reef organisms cannot live in highly saline evaporating brines. • The relationships between the growth of the reefs and the formation of the evaporites in the Michigan Basin are not completely understood.

Answer 27

• Appalachian mobile belt - first Phanerozoic orogeny in North America began in the Middle Ordovician. • The mountain building from the orogeny affected the climate and sedimentary history of the craton • From Sauk time (Neoproterozoic to Early Ordovician), the Appalachian region was a broad passive continental margin. • The Iapetus Ocean was growing at a divergent plate boundary. • The Appalachian mobile belt became “mobile” once the oceanic Iapetus plate began to subduct under the continental Laurentia plate. The Taconic orogeny occurred beginning with the collision of an island arc with Laurentia.

Answer 28

1. Shallow water carbonate platform • Extended from Newfoundland to Alabama. • Formed during the transgression of the Sauk Sea. • Carbonate deposition ceased along the east coast in the Middle Ordovician. 2. Deep-water deposits • Replaced the carbonates. • The sediments mark the onset of mountain building and volcanism, the Taconic orogeny. • Black shales, sandstones, graywackes, and volcanic deposits. • Deep-sea lava flows, volcanic ash layers, and intrusive igneous bodies from present-day Georgia to Newfoundland during the Middle to Late Ordovician.

Answer 29

an extensive accumulation of mostly detrital sediments deposited adjacent to uplifted areas. – Associated with the Taconic orogeny, called the Queenston Delta. – Sediments are thickest and coarsest near the originating highlands and become thinner and finer-grained away from the source area. – Eventually grade into carbonate cratonic facies (west of the highlands). • For example the Queenston Delta Clastic Wedge – More than 600,000 cubic kilometers of rock weathered and eroded to form the Queenston Delta sedimentary rocks. – Based on this volume, the Taconic Highlands were at least 4,000 meters high (similar to Canadian Rockies today).

Answer 30

• Sand and gravel can be mined from Queenston delta sediments (construction) • Limestone (cement). • Silica sand from basal sandstones - used in manufacturing of glass and refractory bricks and as hydraulic fracturing sands in oil and gas recovery. • Gypsum (drywall and plaster). • Halite (seasoning, de-icing, chemicals).

Answer 31

- devonian - carboniferous (Mississippian and Pennsylvian) - permian

Answer 32

• Coals, evaporites, and tillites indicate a variety of climatic conditions during the Late Paleozoic. • Major glaciations and warmer interglacial episodes occurred over much of Gondwana as the continent continued to move over the South Pole during the Late Mississippian to Early Permian. • Waxing and waning glaciers had profound effects on sea level and biota. • Continental collisions produced the supercontinent Pangaea by the end of the Permian and produced high mountains that affected oceanic and atmospheric circulation patterns.

Answer 33

– Following the Taconic orogeny, the southern Iapetus Ocean narrowed between Laurasia and Gondwana. – Mountain-building continued along the eastern margin of Laurasia from the Acadian orogeny. – Erosion of the highlands produced vast amounts of red fluvial sediments in northern Europe (Old Red Sandstone) and the eastern US (the Catskill Delta).

Answer 34

– Gondwana moved over the South Pole, resulting in extensive continental glaciation. – Advancing and retreating glaciers affected eustatic sea level and sedimentation patterns on the cratons. – Gondwana began colliding with Laurasia during the Early Carboniferous, which resulted in the Hercynian, Appalachian, and Ouachita mobile belts. – The Ouachita Mountains of Oklahoma and Arkansas formed last, during the Late Carboniferous and Early Permian. – The Carboniferous coal basins of the eastern US, western Europe, and the Donets Basin of the Ukraine lay near the equator. The absence of strong seasonal growth rings in tree fossils indicate that the climates were warm and wet.

Answer 35

– Pangaea fully assembled. – Panthalassa was the enormous ocean that surrounded Pangaea. – The waters of Panthalassa probably freely circulated, which led to more equable water temperatures worldwide. – The large landmass of Pangaea and the high mountains from the Hercynian (Variscan), Alleghenian, and Ouachita orogenies resulted in widespread arid and semiarid climates on the supercontinent – rain shadow of high mountains. – Extensive Permian red beds and evaporites occurred in western North America, central Europe, and parts of Russia.

Answer 36

``` • Late Paleozoic climates of North America were diverse and included periods that produced extensive: – Shallow-marine carbonates. – Swamps that resulted in coal. – Dry evaporite-forming conditions. • Large fluctuations in eustatic sea level from advancing and retreating glaciers. • Ordovician Taconic orogeny continued with the Caledonian, Acadian, Alleghenian and Ouachita orogenies, which were associated with the assembly of Pangaea. ```

Answer 37

• Middle Devonian to Late Mississippian • Boundary with underlying Tippecanoe Sequence is marked by a major unconformity. • Kaskaskia Sea transgressed over a low-relief craton. • Most basal deposits are well-sorted quartz sandstones (e.g., Oriskany Sandstone of New York and Pennsylvania). • In the US, the sediment sources of the basal Kaskaskia sandstones were mostly the eroding highlands of the Appalachian mobile belt, exhumed Cambrian and Ordovician sandstones along the flanks of the Ozark Dome, and exposures of the Canadian Shield in the Wisconsin area. • Other basal rocks of the Kaskaskia Sequence are carbonates. • Except for widespread Upper Devonian and Lower Mississippian black shales, the majority of Kaskaskian rocks are carbonates, including reefs, and associated evaporites. • Major reef building occurred in many parts of the world during the early Late Devonian. – After the deposition of the Upper Devonian to Lower Mississippian black shales, extensive shallow sea carbonate deposition resumed on the North American craton for the rest of the Mississippian period. – The Mississippian carbonates contain crossbedding, ripple marks, and abundant crinoid fossils – Reefs were abundant, but much smaller than the complexes of the earlier Paleozoic. – During the Late Mississippian, the Kaskaskia Sea regressed from the North American craton. – Detrital clastic sediments, including the petroleum-bearing sandstones of the Illinois Basin, replaced the carbonates. – Weathering and erosion produced a cratonwide unconformity, which marked the end of the Kaskaskia Sequence.

Answer 38

– These Middle and Late Devonian reefs have large reserves of petroleum. – Reefs formed as the Kaskaskia Sea transgressed southward in western Canada. – By the end of the Middle Devonian, the reefs coalesced, restricted the flow of seawater and extensive evaporites precipitated. – More than 50% of the world's potash, which is used in fertilizers, comes from these evaporites.

Answer 39

– Beginning in the Middle Devonian and continuing into the Late Devonian, the deposition of shales and coarser detrital rocks replaced carbonate-evaporite deposition in parts of North America. – The detrital deposits originated from the rising mountains of the Acadian orogeny. • Black Shales – By the end of the Devonian, widespread black shales were forming over much of the North American craton. – The Chattanooga Shale in the eastern US. – Upper Devonian-Lower Mississippian black shales are typically noncalcareous, thin bedded, and less than 10 meters thick. – Fossils are rare. Some Devonian black shales contain conodonts – Exact origin of the shales is debated. – Formed in undisturbed anaerobic bottom waters in shallow seas. – High biologic activity in overlying oxygenated surface waters. – Organic matter rained down on the seafloor and depleted the sediment-water interface of dissolved oxygen. – Black shales contain uranium and are petroleum source rocks.

Answer 40

• Pennsylvanian through Early Jurassic • The unconformity between the Kaskaskia and Absaroka sequences essentially separate the North American Mississippian and Pennsylvanian systems and the European Upper and Lower Carboniferous systems. • The lower-most sediments of the Absaroka Sequence are largely confined to the margins of the North American craton. • The deposits were thickest in the east and southeast, near the highlands of the Appalachian and Ouachita mobile belts. • The rocks laterally change from nonmarine detrital rocks and coals in the east to largely marine detrital and carbonates in the west. – Intracratonic basins filled with sediment during the Late Pennsylvanian. – Absaroka Sea slowly retreated from the craton. – In the Early Permian, the sea extended from Nebraska to west Texas.

Answer 41

– Severe cratonic deformation in North America during the Pennsylvanian period. – Greatest deformation in southwest, formed Ancestral Rocky Mountains. – Precambrian igneous and metamorphic rocks and overlying Paleozoic sedimentary rocks were eroded. – Red arkosic sandstones and conglomerates accumulated in surrounding basins. – The uplift may have resulted from the collision of Gondwana with Laurasia along the Ouachita mobile belt. • Mountain building during the Late Paleozoic had profound effects on climate and sedimentation history, and wasassociated with the formation of Pangaea during the Permian.

Answer 42

– Thick evaporites were deposited in Kansas and Oklahoma by the Middle Permian. – By the Middle Permian, the Absaroka Sea had retreated southward to western Texas and southern New Mexico. – During the Middle and Late Permian, lagoons, massive reefs, and open-shelf environments of the Absaroka Sea existed in western Texas and southern New Mexico. – During the Middle to Late Permian, limestone, evaporites, and red bed sandstones accumulated behind massive reefs in western Texas and southern New Mexico. – Important petroleum reserves occur in the Permian reefs. – By the end of the Permian period, the Absaroka Sea had retreated off the North American craton.

Answer 43

– During the Neoproterozoic and Early Paleozoic, the Cordilleran area of western North America was a passive continental margin. – During the Late Devonian and Early Mississippian, the Antler orogeny occurred. • Subduction? began along the former passive margin, and an eastward moving island arc collided with the western part of the North American craton to produce a highland area.

Answer 44

– Caledonian mobile belt in western Baltica (now Scotland, Ireland, and Norway). – During Middle Ordovician, subduction of oceanic Iapetus plate under Baltica continent. – Caledonian orogeny - Mountain building along the western margin of Baltica. – Clastic deposition - Old Red Sandstone. – From Newfoundland to Pennsylvania. – Northern oceanic Iapetus plate subducted under Laurentia. – Orogeny occurred when Baltica continent collided with Laurentia continent to form Laurasia. – Weathering of the highlands produced the Catskill Delta and Old Red Sandstone clastic wedges.

Answer 45

– The remains of the belt currently extend from the subsurface of Mississippi to the Marathon region of western Texas. – During the Neoproterozoic to the Early Mississippian in this region, shallow-water detrital and carbonate sediments accumulated on a broad continental shelf. – Bedded cherts and muds that became shales formed in deeper waters. – The Ouachita orogeny began in the Mississippian period as the region changed from a passive continental margin into an active convergent plate boundary. – The orogeny continued through the Pennsylvanian and Early Permian periods as Gondwana collided with Laurasia. – A large mountain range, including the Ouachita and Marathon mountains, formed – Ozarks of Arkansas are all that’s left. – The mountains largely eroded during the Mesozoic Era. – Microplates collided to form part of Central America. – The compressive forces of the Ouachita mobile belt also broadly uplifted the southwestern part of the North American craton.

Answer 46

– Hercynian mobile belt of Europe and the Appalachian and Ouachita mobile belts of North America mark where Laurasia collided with Gondwana. – Gondwana and southern Laurasia collided in the Ouachita mobile belt during the Pennsylvanian and Permian. – Eastern Laurasia (Europe and southeastern North America) collided with Gondwana (Africa) as part of the Hercynian (Variscan)- Alleghenian orogeny. – Hercynian (Variscan) fold belt was in Europe. The Alleghenian tectonic event was in the North America. – The Hercynian (Variscan)- Alleghenian orogeny began during the Mississippian and became more intense during the Pennsylvanian and Permian periods. – The Hercynian (Variscan), Alleghenian, and Ouachita orogenies represent the joining of Laurasia and Gondwana to form the supercontinent Pangaea.

Answer 47

• Numerous microplates and continental terranes existed during the Paleozoic. • These microplates and terranes contributed to orogenies and the formation of Pangaea. • Avalonia microcontinent (Atlantic Canada) • Iberia-Armorica terrane-microplate - Iberian peninsula and surrounding parts of southwestern Europe. • Perunica (Bohemia). • Numerous Alpine fragments (Austria). • Paleozoic terranes and microplates separated from continents and collided with other continents. • Paleozoic terranes and microplates often developed their own unique fossil assemblages (fauna ; flora).

Answer 48

``` • Oil and natural gas deposits. – Devonian rocks of Alberta and the Michigan, Illinois, and Williston (North Dakota and Montana) basins. – Natural gas in Devonian black shales. – Permian reefs of western Texas. • Coal (especially Pennsylvania period). – Bituminous – Anthracite (Pennsylvania) • Salt deposits. – Permian Delaware Basin of Texas. – Zechstein deposits of Europe. – Devonian Elk Point Basin, Canada. – Michigan Basin. • Limestone - used in manufacturing of cement and steel. • Silica sand - glass manufacturing and bricks for blast furnaces. • Tin, copper, gold, and silver in Late Paleozoic rocks. • Lead and zinc deposits in Mississippian rocks of Missouri. ```

Answer 49

• In 1909, geologist Charles D. Walcott discovered the impressions of numerous Middle Cambrian soft-bodied organisms in the Burgess Shale of British Columbia, • The deposition site for the Burgess Shale was the base of a steep submarine escarpment. • The animals preserved in the shale lived on mud banks that formed along the top of the escarpment. • Occasionally, the mud banks would become unstable and the community would slide down the slope of the escarpment as a turbidity current. • The organisms would be buried and preserved in the deep-water anaerobic environment. • The anaerobic water and muds prevented bacteria and scavengers from destroying the soft-bodied organisms. They were preserved as carbonaceous films.

Answer 50

• Multicelled Ediacaran fauna presumably had a long Precambrian history, but they lacked hard parts and were not well-preserved in the fossil record. • The "Cambrian explosion" refers to the appearance of many different skeleton bearing animal fauna in the Early Cambrian. • The animals evolved over several million years in the Early Cambrian. • Scientists investigate the Cambrian explosion by: – Looking for new fossil localities. – Comparing the molecular sequences of the same gene from different living species to determine their evolutionary history. – Hox genes Basic body plans evolved by the Early Cambrian. • The cause(s) of the relatively rapid evolution is still debated. • More than likely, the explosion was due to a number of biologic and geologic factors, perhaps including: – Glaciations in the Proterozoic followed by global warming in the Cambrian. • Other possible geologic and biologic factors for the Cambrian explosion: – Possible changes in ocean chemistry could favor the evolution of mineralized skeletons. • Possible increases in the calcium concentration of ocean water from increased volcanism. – Evolution of predators. • In response, shells and skeletons would offer greater protection from predators and survival.

Answer 51

• Earliest known organisms with hard parts were small and calcareous tubes found in the Neoproterozoic Ediacaran faunas. • These were followed by microscopic skeletonized fossils in the Early Cambrian. • Endoskeletons, internal. • Exoskeletons, external, including shells. • Skeletons would provide organisms with the following advantages: – Protection against predators. – Protection against ultraviolet radiation, which would allow them to live in shallower water. – Protects the animal from drying out in an intertidal environment. – Provides support for muscles to attach, which allows the sizes of the organisms to increase. • Early Cambrian fossil record indicates that the evolution of shelly invertebrates was a response to the evolution of new predators.

Answer 52

• At the beginning of the Paleozoic, abundant animals with skeletons appeared. • The end of the Paleozoic witnessed the worst mass extinction in the Earth's history.

Answer 53

1. Protozoans - first animals, unicellular eukaryotes 2. Porifera - sponges, multi-celled, filter feeding animals, first group to branch off from other animals 3. Archaeocyatha - "ancient cups", multi-celled, filter feeding animals 4. Cnidaria - jelly fish, coral 5. Bryozoa - "moss animals", filter feeders 6. Barchiopoda - had upper and lower valves vs. left and right in bivalves 6. Mollusca 7. Annelida - segmented worms 8. Arthropoda - trliobites, insects, scorpians, crabs, lobsters 9. Echinodermata - sea urchins, sea cucumbers, 10. Hemichordata - acorn worm, graptolites

Answer 54

– Major transgressions on world's cratons opened up vast shallow seas for inhabitation. – Plate tectonics not only affected ocean circulation patterns, but also environments and biota.

Answer 55

– New body plans evolved. – Animals moved into new ecologic niches. – High percentage of evolutionary experiments. – Almost all major invertebrate phyla evolved during the Cambrian, but some phyla only had a few species. – Trilobites, inarticulate brachiopods, and archaeocyathids were major skeletonized invertebrates. – Trilobites • About 50% of total Cambrian fauna. • Arthropods. • Benthonic, mobile, sediment feeders. – Brachiopods • Inarticulate - Chitinophosphate shells. • Articulate - teeth and sockets, calcite shells. • Benthonic, sessile, suspension feeders. – Archaeocyathids • Formed reefs • Extinct by end of Cambrian. • Benthonic, sessile, possible suspension feeders

Answer 56

– Sauk Sea transgressed the Cordilleran shelf and onto the western edge of the North American craton. – Middle Cambrian mud banks formed. – Many of the soft-bodied organisms are now extinct. – They have the basic body plans from which all modern invertebrates evolved – For years, most paleontologists placed the bulk of the Burgess Shale biota into existing phyla. – Other paleontologists now think that the biota represent evolutionary “experiments” involving many phyla that went extinct. – Debates continue over the classification of the biota.

Answer 57

– Major transgression of the Tippecanoe Sea began in the Middle Ordovician. – Many new marine habitats were soon filled by a variety of organisms. – Brachiopods diversified. – Adaptive radiation of bryozoans – Increased diversity and abundance of acritarchs (organic walled phytoplankton). – Bryozoans, stromatoporoids, and tabulate and rugose corals became major reef builders in the Middle Ordovician. – Articulate brachiopods diversified in shallow marine environments. – Graptolites (extinct) - planktonic animals abundant in Ordovician and Silurian. - Conodonts (extinct) - microscopic tooth-shaped feeding apparatus from an eel-like jawless swimming animal.

Answer 58

– Occurred at the end of the Ordovician. – More than 100 families of marine invertebrates became extinct. – In North America, about 50% of brachiopods and bryozoans died out. – Extinction may have been caused by extensive glaciation at the South Pole on Gondwana – Sea levels would have decreased, perhaps limiting available habitat – Many other hypotheses • Anoxia, volcanism, gamma ray burst – Surface waters cooled and would have stressed the phytoplankton acritarchs. – Impacted the marine food web.

Answer 59

– After the Ordovician mass extinction,brachiopods, bryozoans, gastropods, bivalves, corals, crinoids, and graptolites rediversified at the beginning of the Silurian. – Major reef building in Silurian and Devonian. – Stromatoporoids and tabulate and colonial rugose corals dominated the Silurian and Devonian reefs. – Unlike many marine invertebrates, scorpion-like eurypterids (Phylum Arthropoda) also lived in brackish and fresh waters. – Ammonoids, a subclass of cephalopods, evolved from nautiloids in the Early Devonian and rapidly diversified. – Their distinctive suture patterns, short stratigraphic ranges, and widespread distribution make them excellent guide fossils for the Devonian through the Cretaceous.

Answer 60

– World-wide near-total collapse of reef communities. – Land-dwelling seedless vascular plants seemingly unaffected . – Tropical marine groups were most severely affected, whereas higher latitude marine communities were not. – Global cooling may have been responsible. – Tropical organisms would have been severely affected. – Marine organisms living in cooler water could have migrated closer to the equator and survived. – The closing of the Iapetus Ocean also reduced the area of shallow shelf environments, where many marine invertebrates lived.

Answer 61

– Brachiopods and ammonoids quickly recovered after the Late Devonian extinction. – Lacy bryozoans and crinoids reached their greatest diversity during the Carboniferous. – With the decline of stromatoporoids and tabulate and rugose corals, reefs were smaller patches consisting of crinoids, blastoids, lacy bryozoans, brachiopods, and calcareous algae.

Answer 62

– Permian marine invertebrate communities resembled Carboniferous ones. – Bryozoans, sponges, and various types of calcareous algae were common. – Permian communities not as widely distributed due to restricted size of shallow seas on the cratons and less shelf space along the continental margins as Pangaea formed. – Spiny or productid brachiopods important in Texas reef complexes. – Fusulinid foraminifera (microscopic calcite-shelled organisms) first evolved in the Late Mississippian. – They greatly diversified during the Pennsylvanian. – They experienced further diversification during the Permian. – Fusulinids are important guide fossils for the Pennsylvanian and Permian.

Answer 63

• The discovery of 397-million-year-old (earliest Middle Devonian) footprints in Poland changed our views of the origin and early evolution of tetrapods. • Tetrapod means "four foot" and refers to intermediates between fish and the earliest amphibians. • The Polish footprints indicate that the transition from lobe-finned fish to tetrapods occurred earlier than previously realized. • The early tetrapods lived in coral-reef lagoons rather than streams, lakes, or swamps as previously thought. • In the Paleozoic Era, vertebrates and plants moved from water onto land. • For both groups, the biggest barrier in the transition to land was the method of reproduction. • Evolution of seed plants and the amniote egg in animals removed this barrier.

Answer 64

• The ancestors and early members of the phylum Chordata were soft-bodied organisms that left few fossils. • Chordate (Phylum Chordata) - an animal that at least during part of its life cycle has: – a notochord. – a dorsal hollow nerve cord. – pharyngeal slits. • Vertebrates are a subphylum of Chordata. • Yunnanozoon lividum is one of the oldest known chordates and lived in China 525 Ma - Cambrian • Embryology suggests that chordates and echinoderms may have shared a common ancestor. • In embryos, the cells of chordates and echinoderms divide by radial cleavage so that they are aligned directly above each other. In all other invertebrates, cells undergo spiral cleavage. • Biochemistry of muscle activity and blood proteins are also similar. • Fossils and evidence from molecular biology suggest that vertebrates evolved shortly after their ancestral chordate, which may have resembled Yunnanozoon lividum.

Answer 65

• The most primitive vertebrates are fish. • The earliest known fish remains are Upper Cambrian. – Phosphatic scales and plates of Anatolepis, a primitive marine jawless fish (class Agnatha). • All known Cambrian and Ordovician fish were marine. • Earliest freshwater fish from the Silurian. • Ostracoderms - "bony skin" are the oldest fish in the class Agnatha. • Ostracoderms were armored, jawless fish that evolved during the Late Cambrian and became extinct in the Devonian. • Most ostracoderms lived on the seafloor, including Hemicyclaspis. • The vertical scales of Hemicyclaspis wiggled sideways, which allowed the fish to propel itself along the seafloor. • The eyes on the top of its head allowed it to see predators above. • The fish probably sucked up bits of food in sediments through its jawless mouth. • Pteraspis, another ostracoderm, was more elongated than Hemicyclaspis and probably an active swimmer.

Answer 66

– Studies suggest that jaws evolved from the first two or three anterior gill arches of jawless fish. – The evolution of the jaw may have been first related to respiration rather than feeding. – By evolving joints in forward gill arches, fish could open their mouths wider. – By opening and closing its mouth, more oxygenbearing water could be pumped by the gills. – The modification from rigid to hinged forward gill arches let fish increase both their food and oxygen intake. – The evolution of the jaw as a feeding structure quickly followed. – The earliest jawed fishes are Early Silurian and are acanthodians (class Acanthodii).

Answer 67

- Agnatha - Acanthodii - Placodermii - Chondricthyes - Osteichthyes

Answer 68

– They had large spines, paired fins, scale coverings over much of their bodies, and reduced body armor. – They may have been the ancestors of present-day bony and cartilaginous fish groups. – Acanthodians were most abundant in the Devonian and became extinct in the

Answer 69

– Another group of jawed fishes. – Evolved during the Silurian. – Heavily armored. – Lived in both the ocean and freshwater. – Placoderms showed great diversity and included bottom dwellers and predators. – They reached peak abundance and diversity during the Devonian and became extinct in the Permian. – Included the large Late Devonian predator, Dunkleosteus. – Dunkleosteus lived in mid-continental North American epeiric seas. – Possibly more than 12 metres long. – Heavily armored head and shoulders. – Flexible tail. – Huge jaw with sharp bony teeth.

Answer 70

– Evolved during the Devonian. – Cartilaginous fish include modern sharks, rays, and skates. – Cladoselache - primitive Late Devonian shark.

Answer 71

– Bony fish evolved during the Devonian. – Two groups: • Ray-finned fish (subclass Actinopterygii) • Lobe-finned fish (subclass Sarcopterygii) – Amphibians evolved from lobe-finned fish. – Ray-finned fish include modern trout, bass, perch, salmon, and tuna. • Lobe-finned Bony Fish – Modern species characterized by muscular fins. – Coelacanths (order Coelacanthimorpha) • Marine. • Evolved in Devonian. • Thought extinct in the Cretaceous until discovered in 1938 off the coast of Madagascar. – Lungfish (order Dipnoi) • Fairly abundant in the Devonian. • Today only three freshwater genera exist. • "Lung" is a modified swim bladder, mostly used for buoyancy. Lungfish have gills. • The lung takes in air and allows the fish to survive when lakes and streams dry up. • The fish burrows into sediment to prevent dehydration and breathes through the lung until water returns to the lake or stream. – Crossopterygians (order Crossopterygii) a type of lung fish • Rhipidistian (suborder Rhipidistia) crossopterygians were probably the amphibian ancestral group. • Rhipidistrians were dominant freshwater predators during the Late Paleozoic. • Eusthenopteron - a rhipidistrian and transition form between fish and amphibians. • Eusthenopteron - elongated body for swimming and muscular fins for moving on land. – Bony fish expanded during the Late Paleozoic.

Answer 72

– Ostracoderms, although armored, would have been easy prey for swifter jawed fish. – Ostracoderms became extinct at the end of the Devonian, which coincided with the rapid evolution of jawed fish. – Placoderms, like acanthodians, greatly decreased in abundance after the Devonian and became extinct in the Permian.

Answer 73

• During the Devonian, amphibians were the first vertebrates to live on land. • Land plants evolved in the Ordovician. • Insects, spiders, and perhaps snails also became land-living before amphibians. • To live on land, vertebrates had to overcome several barriers: – Desiccation (avoid drying out). – Reproduction (amniote egg). – Effects of gravity. – Lungs for respiration. • Limbs probably originally evolved to help fish move around in streams, lakes, or swamps choked with plants and other debris. • Fossils of Acanthostega, a tetrapod found in the 360 mya Old Red Sandstone from Greenland, had limbs, but the limbs were too weak to allow the animal to walk on land. • Acanthostega had both lungs and gills. • Ichthyostega, the oldest known amphibian, could walk on land and fossils are found in the Upper Devonian Old Red Sandstone of Greenland. • In 2006, the "fishapod" Tiktaalik roseae was discovered in Late Devonian rocks on Ellesmere Island, Canada. • It is an intermediate between lobe-finned fish and Acanthostega. • Tiktaalik had gills and scales like a fish, but true tetrapod forelimbs, which included functional wrist bones and five digits. • Late Paleozoic amphibians came in a variety of sizes, shapes, and modes of life, but did not resemble modern frogs, toads, newts, and salamanders. • Labyrinthodonts. – Up to 2 meters in length. – Lived in streams and swamps. – Ate fish, other amphibians, vegetation, and insects. – A few species survived into the Triassic.

Answer 74

• Tropical organisms tend to be more affected than organisms in temperate or high latitudes. • Species in many different phyla are affected, but in most cases the phyla survive. • Archaeocyatha is an example of an extinct phylum. • During the past 650 million years, the first extinction only affected acritarchs. • Several extinctions occurred in the Cambrian, but only affected marine vertebrates, especially trilobites. • Ordovician mass extinction. • Devonian mass extinction - reefs and fish. • Permian mass extinction - worst in Earth's history. • Several Mesozoic mass extinctions. – Late Cretaceous was the worst. • Dinosaurs, flying reptiles, ammonoids, and marine plesiosaurs and ichthyosaurs became extinct. • Perhaps due to an asteroid impact . • Several Cenozoic mass extinctions. – Most severe at the end of the Eocene Epoch. • Probably due to global cooling. – Extinction at the end of the Pleistocene. • Mostly affected large mammals. • Marine mass extinctions may have occurred over hundreds of thousands or even millions of years. • Most mass extinctions probably due to climate changes rather than single global catastrophes, such as asteroid impacts.

Answer 75

– About 96% of marine invertebrate species went extinct. – Fusulinids, rugose and tabulate corals, trilobites, blastoids, and several orders of bryozoans and brachiopods disappeared. – Extinction of about 70% of terrestrial vertebrate species. – Nearly 33% of land insects went extinct. – Cause(s) uncertain. – Extinctions occurred over several millions of years, so an asteroid impact is unlikely. – Reduced marine shelf area from the formation of Pangaea is unlikely. • The supercontinent formed before the extinction. – Glaciations waned in the Permian and are also eliminated as a cause. – Deep-sea anoxia and increased CO2 levels in the oceans are possible causes. • Very little O2 circulated into deep oceans. • Stagnant waters would have covered shelf regions. – Global warming is another possible cause. • Would have eliminated downwelling of cold, dense, and oxygenated waters from polar regions into lower latitudes. • Resulted in stagnated and stratified oceans rather than well-mixed and oxygenated waters. – Widespread volcanism during the Late Permian. • Massive fissure eruptions in Siberia. • Released large amounts of greenhouse CO2 into the atmosphere. • Chlorine and fluorine from the eruptions would have damaged the ozone layer and increased the exposure of organisms to ultraviolet radiation.

Answer 76

• Amphibians were limited in colonizing the land because they had to return to water to lay their gelatinous eggs. • The evolution of the amniote egg freed reptiles from that restraint. • Amniote egg - the developing embryo is surrounded by a liquid-filled sac - amnion. • The egg has a yolk (food sac) and allantois (waste sac). • Reptiles also differ from amphibians in skull structure, jawbones, ear location, and limb and vertebrate construction. • Reptiles probably evolved from labyrinthodont amphibians by the Late Mississippian. • Oldest known reptile is Westlothiana from Late Mississippian rocks in Scotland. • Early reptiles were loosely grouped together as protorothyrids. • During the Permian, reptiles diversified and replaced amphibians. • Reptiles were successful because of their eggs, advanced jaws and teeth, tough skin and scales to prevent desiccation, and their ability to rapidly move on land. • Pelycosaurs, or finback reptiles, evolved from protorothyrids during the Pennsylvanian and became the dominant reptile group in the Permian. – Edaphosaurus - a herbivore. – Dimetrodon - a carnivore. • The purpose of the back sail is unknown. – Possibly to regulate body temperature by catching the Sun's rays or cooling with wind. • Therapsids, mammal-like reptiles, evolved from carnivorous pelycosaurs in the Permian. • Pelycosaurs became extinct during the Permian. • Therapsids diversified into herbivores and carnivores. • 2/3 of all reptiles and amphibians became extinct at the end of the Permian, but therapsids survived into the Triassic. • Therapsids displayed the beginnings of mammalian features: – Fewer skull bones. – Enlarged lower jawbone. – Differentiation of teeth. – More vertical legs. – Possibly covered with fur. – May have been endothermic - warm blooded. – They lived in cooler middle and higher Permian latitudes, and not just low latitudes.

Answer 77

• When plants made the transition from water to land, they had to solve many of the same problems as animals: – Avoiding desiccation. – Developing support. – Reproduction. – Effects of gravity. • Plants initially evolved in seawater, then moved into freshwater, and finally onto land. • Land plants divided into: – Vascular. • Majority of modern land plants. • Tissue system of specialized cells for movement of water and nutrients. – Nonvascular. • Bryophytes (liverworts, hornworts, and mosses). • No specialized cells. • Tend to live in moist areas. • Earliest land plants in Middle to Late Ordovician. – Probably nonvascular. – Fossil plants with spores in Libya. • Vascular plants evolved well before the Middle Silurian. • Ancestor of vascular plants probably some type of green alga. • No fossil transition found. • Physiology indicates a link between green algae and vascular plants. • Primitive seedless vascular plants (for example, ferns) resemble green algae in their pigmentation, important metabolic enzymes, and type of reproductive cycle. • Green algae are one of the few plant groups to transition from marine to freshwater. • Vascular tissues give support for land plants. • Additional strength comes from lignin and cellulose in the plant walls. • Cutin, an organic compound found in the outer walls of land plants, provides protection against desiccation, ultraviolet radiation, oxidation, and parasites. • Roots and leaves improved nutrition.

Answer 78

– Cooksonia: • Earliest known vascular land plant. • Middle Silurian of Wales and Ireland. – Earliest vascular land plants. • Small, simple, leafless stalks. • Seedless. • Spore-producing structures. • No true roots. • Rhizome, underground part of the stem, provided water and anchored the plant. – Leaves, roots, and other plant structures did not evolve simultaneously, but at different times - mosaic evolution. – Land plants greatly diversified during the Late Silurian and Early Devonian. – By the Late Devonian, forests of large treelike plants (up to 10 meters tall) existed. – Seedless vascular plants require moisture for fertilization. – The evolution of seeds in the Late Devonian allowed land plants to become independent of moist conditions and spread over the Earth. – Gymnosperms - flowerless seed plants, have male and female cones. – Before seed plants evolved, heterospory - species produced two types of spores. Early Devonian plant - Chaleuria cirrosa. – Millions of years after the evolution of heterospory, progymnosperms evolved in the Middle to Late Devonian. – Progymnosperms - fern-like reproductive plants with gymnosperm anatomy. – Progymnosperms gave rise in the Late Devonian to seed plants.

Answer 79

– Mississippian flora similar to Late Devonian. – Pennsylvanian (Late Carboniferous) - major source of world's coal. – Coal - altered plant remains that accumulated in low, swampy areas. – Seedless vascular plants dominated flora of Carboniferous coal-forming swamps. – Gymnosperms also important, especially in non-swampy areas. – Seedless vascular plants, the lycopsids and sphenopsids, most important coal-forming groups in the Pennsylvanian period. – Lycopsids were small in the Devonian, but in the Pennsylvanian, they achieved heights of 30 meters as Lepidodendron and Sigillaria. – Calamites - 5 to 6 meter-tall sphenopsid. – Living sphenopsids include the horsetail and scouring rushes. – Cordaites - group of tall Pennsylvanian gymnosperm trees that lived on higher and drier ground. – Glossopteris - nonswamp plant that was so abundant in Gondwana that it became major evidence of continental drift. – Pennsylvanian floras generally persisted into the Permian, but climatic changes caused them to become less abundant. • The End of the Paleozoic Era – Cordaites became extinct at the end of the Permian. – Lycopsids and sphenopsids reduced in size after the Permian. – Gymnosperms were better adapted to warmer and drier climates, and came to dominate the Permian, Triassic, and Jurassic landscapes

Answer 80

• Magnetic anomalies are well preserved in the ocean crust associated with the breakup of Pangaea. • The magnetic anomalies help determine the movement of continents during the Mesozoic and Cenozoic eras.

Answer 81

• The breakup of Pangaea began with the separation of Laurasia from Gondwana during the Triassic period. • By the end of the Triassic, the newly formed and expanding Atlantic Ocean separated North America from Africa. • The breakup of Pangaea allowed water from the Tethys Ocean (or Sea) to flow into the expanding central Atlantic Ocean. • During the Late Triassic and Early Jurassic, North America separated from South America. • Waters from the Pacific Ocean flowed into the newly formed Gulf of Mexico basin. • Thick evaporites precipitated in the basin. • Gondwana broke up during the Late Triassic and Jurassic.

Answer 82

* Antarctica and Australia remained sutured together, but separated from Africa, India, and South America. * India moved northward. * South America and Africa began separating during the Jurassic with shallow seawater precipitating evaporites in the rift zone. * The eastern end of the Tethys Ocean began closing to form a narrow Late Jurassic and Early Cretaceous seaway between Africa and Europe, the forerunner of the modern Mediterranean Sea.

Answer 83

• By the end of the Cretaceous: – Australia and Antarctica had separated. – India had moved into the low southern latitudes. – South America and Africa were widely separated by the growing south Atlantic Ocean. – Greenland had separated from Europe and North America. • Seas transgressed the continents in the Cretaceous. • Higher heat flow and expansion of oceanic ridges likely explain the rise in global sea level – higher ocean floor = less volume. • By the Middle Cretaceous, about 1/3 of the continents were covered by epeiric seas • The final breakup of Pangaea occurred in the Cenozoic.

Answer 84

– Climates result from complex interactions between wind, ocean currents, and the location and topography of the continents. – During the Permian, arid climates occurred over much of the large interior of Pangaea because: • The interiors of supercontinents are far from oceanic sources of moisture. • Mountain ranges also block moisture. – Sedimentary rocks often provide important clues about depositional environments. • Evaporites, extensive red beds (sandstone) and sand dunes form in deserts. • Coals - warm or cool moist climates. – During the Triassic, low and middle latitudes were often dry with evaporites and red beds. Coals indicate high latitudes were wetter. – Seasonal monsoons along the Triassic Tethys Ocean. – Continents moving northward from the breakup of Pangaea in Late Triassic caused temperature decreases in the high latitudes. – With the breakup of Pangaea, atmospheric circulation patterns greatly accelerated in the Mesozoic – Relatively equable worldwide climates persisted through the end of the Cretaceous..

Answer 85

- During the Jurassic and Cretaceous, the middle- and low-latitude oceans were still quite warm. – With the breakup of Pangaea, oceanic patterns greatly accelerated in the Mesozoic.

Answer 86

• Global sea rise in Cretaceous. • Marine deposition over much of North American Cordilleran.

Answer 87

• Volcanic island arc off the west coast of North American craton sutured onto North America in the Permian or Triassic (subduction). This was the Sonoma orogeny. • During the Jurassic, the Sierra Nevada, Rocky Mountains, and other lesser mountain ranges formed during the Cordilleran orogeny.

Answer 88

the Paleozoic of North America consisted of a series of marine transgressions and regressions. • Marine transgressions and regressions were not as important in North America during the Mesozoic Era – Deposition in some interior seaways, typically adjacent to uplifting mountain ranges – Appalachian mountains continue to erode • Most of the continental interior of North America was above sea level during the Mesozoic. • Two sequences in the Mesozoic - the Absaroka Sequence (Late Mississippian to Early Jurassic) and the Zuni Sequence (Early Jurassic to Early Paleocene).

Answer 89

• During Early to Middle Triassic, coarse detrital sediments from the eroding Appalachian Mountains (Alleghenian orogeny) filled surrounding basins. • The heights of the Appalachian Mountains were greatly reduced. • During the Late Triassic, North America began to separate from Africa. • Fault-block basins formed from Nova Scotia to North Carolina • Erosion of fault-block mountains produced the thick and poorly sorted non-marine detrital sediments of the mostly Late Triassic and partially Early Jurassic Newark Group. • Extensive lava flows occurred on the floors of the fault-block basins. • Numerous dikes and sills intruded in the basins, including the Palisades sill along the Hudson River in the New York-New Jersey area. • As the Atlantic Ocean formed and grew, the eastern coast of North America transformed from a rifting zone into a passive continental margin. • The fault-block mountains of eastern North America eroded during the Jurassic and Early Cretaceous. • Sediments from the eroding Appalachian Mountains contributed to the growing continental shelf. • During the Cretaceous, the Appalachian region was elevated again and shed additional sediments onto the continental shelf. • These rocks are currently exposed in a belt from Long Island, New York to Georgia.

Answer 90

• The Gulf region was above sea level until the Late Triassic. • North America separated from South America during the Late Triassic and Early Jurassic, and the Gulf of Mexico began to form. • Ocean water flowed into the Gulf of Mexico basin. • Evaporites precipitated in the shallow and restricted basin during the Jurassic. • Evaporites - more than 1,000 meters thick. • By Late Jurassic, the Gulf of Mexico was deeper and less restricted. • Evaporite precipitation ceased and normal marine conditions occurred. • During the Cretaceous, northward transgressing seas flooded the Gulf Coast region. • As part of the transgression, fine-grained deep-water sediments were deposited over nearshore sands. • Following a major regression at the end of the Early Cretaceous, a major transgression created a wide seaway from the Arctic to the Gulf of Mexico • Reefs were widespread in the Gulf Coast region during the Cretaceous. • The reefs were mostly composed of rudist bivalves. • Because of their high porosity and permeability, rudist reefs are excellent petroleum reservoirs..

Answer 91

• Except for Late Devonian-Early Mississippian Antler orogeny, little tectonism occurred in the Cordilleran region of western North America during the Paleozoic. • Island arcs and ocean basins off the west coast of North America during the Permian. Sonoma orogeny – During the Permian-Triassic Sonoma orogeny, subduction of the Farallon oceanic plate caused the island arc system to collide with the North American craton. – The island arcs were sutured onto the North American craton and formed the landmass Sonomia. – During the Late Triassic, a steeply dipping subduction zone developed on the western margin of North America. Cordilleran orogeny – The ocean-continent convergence zone involving the Farallon oceanic plate and the western North American continent controlled Cordilleran tectonics for the rest of the Mesozoic and most of the Cenozoic Era. – Cordilleran orogeny refers to the mountainbuilding activity that began in the Jurassic and continued into the Cenozoic Era. – Cordilleran orogeny consisted of a series of mountain-building events that occurred in different regions at different times, but overlapped to some extent. – The events involved the western movement of the North American continental plate and the subduction of the Farallon plate. Nevedan orogeny - was the first event of the Cordilleran orogeny. – Late Jurassic into the Cretaceous. – Large volumes of granitic magma accumulated. – Sierra Nevada, Southern California, Idaho, and Coast Range batholiths formed. – Franciscan Complex • 7,000 meters thick. • Chaotic mix of graywackes, volcanic breccias, siltstones, black shales, chert, pillow basalts. • Continental shelf, slope, and deep-sea sediments and volcanic rocks brought into a submarine trench. • Blueschist metamorphism from subduction - high pressure, temperatures relatively cool. – Great Valley Group - 16,000 meters of conglomerates, sandstones, siltstones, and shales that were deposited on the continental shelf and slope while the Franciscan deposits were accumulating in the trench. – Franciscan Complex and Great Valley Group were squeezed onto the edge of the North American craton by the subducting Farallon plate. – Late Cretaceous • Thrusting occurred farther east up to the Idaho- Washington border. • Most volcanism and plutonic activity migrated eastward into Nevada and Idaho. • Eastward migration caused by the subduction of Farallon plate changing from a high to low-angle. Sevier Orogeny – Second event of the Cordilleran orogeny. – Caused by subducting Farallon plate. – Mostly Cretaceous. – Affected western North America from Alaska to Mexico. – Numerous overlapping low-angle thrust faults. – Produced generally north-south trending mountains from Montana to western Canada. Laramide orogeny – Final episode in the Cordilleran orogeny. – Late Cretaceous to Early Cenozoic. – Occurred east of Sevier orogenic belt. – Rocky Mountains mostly formed in Cenozoic.

Answer 92

– Early Triassic Cordilleran mobile belt includes shallow-water sandstones, shales, and limestones. – During the Middle and Late Triassic, the western shallow sea regressed. – Red beds formed. • Lower Triassic Moenkopi Formation of US southwest. – Lower Triassic Moenkopi Formation • Mudstones. • Mud cracks, ripple marks, and amphibians and reptile tracks. • Depositional environments - streams, floodplains, and freshwater and brackish ponds. • Halite and gypsum crystal casts indicate arid climates – Upper Triassic Shinarump Conglomerate • Unconformably overlies the Moenkopi Formation. – Upper Triassic Chinle Formation • Multicolored shales, siltstones, and sandstones. • Petrified wood of Petrified Forest National Park, Arizona. • Fossils of labyrinthodont amphibians, phytosaurs, and small dinosaurs. • Similar pollen to Lower Newark Group of eastern US - indicates similar ages – Early Jurassic • A lot of large cross-bedded, wind-blown sandstones. • Wingate Sandstone - desert dune deposits. • Kayenta Formation - stream and lake deposits. • Navajo Sandstone - large cross-bedded coastal dunes.. – Middle Jurassic • Sundance Sea twice flooded the interior of western North America and Sundance Formation deposited. – Late Jurassic • Mountains of Nevadan Orogeny shed sediments eastward. • Sediments deposited in the Sundance Sea to form the sandstones, mudstones, shales, and local conglomerates of the Morrison Formation. • Morrison Formation rich in Jurassic dinosaur fossils, which were mostly deposited in streams during flooding. • Soils in Morrison Formation indicate a dry climate. – In the Early Cretaceous, Arctic waters spread southward over the North American craton to form a large in-land sea in the Cordilleran region. – In the Middle Cretaceous, transgressions occurred on other continents, perhaps from the expansion of very active oceanic spreading ridges. – Widespread deposition of black shales occurred in the Middle Cretaceous. – By Late Cretaceous, the Cretaceous Interior Seaway extended from the Arctic to the Gulf of Mexico and occupied the areas to the east of the Sevier orogenic belt. – Sediment deposition was controlled by sealevel changes, climate, and tectonics. – The eastern margin of the Cretaceous Interior Seaway received little sediment from the relatively low relief to the east. – The western shoreline of the seaway shifted back and forth in response to sediment supply from the Sevier orogenic belt to the west. – Facies relationships in the sediments of the western Cretaceous Interior Seaway show lateral changes from conglomerates and coarse sandstones adjacent to mountain belts to finer sandstones, siltstones, shales, and limestones and chalks in the east. – During times of especially active mountain building, clastic wedges of gravels and sands prograded further east. – At the end of the Mesozoic Era, the Cretaceous Interior Seaway withdrew from the craton. – Marine waters retreated north and south. – Marginal marine and continental deposition resulted in the formation of coal-bearing deposits on the coastal plains.

Answer 93

• Terranes are small lithospheric blocks that originated from elsewhere. • They include island arcs, oceanic crust, and small fragments of continents, which accreted onto larger continents. • They differ from each other and continents in fossil content, stratigraphy, structural trends, and paleomagnetic properties. • Perhaps, more than 25% of the western margin of North America originated from the accretion of terranes.

Answer 94

• Mesozoic rocks contain a variety of resources, including coal, petroleum, uranium, gold, and copper. • Important petroleum reserves formed in the Middle East during the Mesozoic Era. • The Jurassic Louann Salt formed, which later created important oil and gas traps in the Gulf of Mexico. • The richest uranium deposits in the US occur as the mineral carnotite in Mesozoic sandstones of the Colorado Plateau of Colorado and adjoining states of Wyoming, Utah, Arizona, and New Mexico. • Jurassic "Minette" iron ores of western Europe. • Some important diamond deposits in South Africa are associated with Cretaceous volcanic kimberlite pipes. • Jurassic intrusive rocks in the Sierra Nevada provided gold for the California "Gold Rush." • The world's largest copper deposits formed during the Mesozoic and Cenozoic along the western margins of North and South America.

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Midterm 2 Flashcards

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