Study Guide—Exam 3—Spring 2008—GEOL3200 Covers all material since last exam, and therefore includes, on some level,: Chs. 3, 9, 10, 11, 12, 13, 14, 15, 16, 17 Paleoproterozoic (2.5-1.6 Ga): major crustal accretion, BIFs galore (>90%), Nuna--our own Farmington Canyon Complex Oldest “definite” ophiolite: ~2.0 Ga--significance red beds common by 1.8 Ga.... oldest eukaryote at 2.1 Ga--endosymbiosis!, multicellular algae at 1.8 Ga Mesoproterozoic (1.6-1.0 Ga): A-type (anorogenic) granites--perhaps not associated with subduction Rodinia! (assembled 1.4-1.1 Ga). Culminating tectonic event was the Grenville orogeny. Acritarchs evolve at 1.4 Ga. Neoproterozoic (1.0-.542 Ga): Rodinia breaks apart at about 800-750 Ma. A short-lived supercontinent reforms (Pannotia) at about 650-600 Ma. In Grand Canyon, a rift-related marine basin records Rodinia break up= Chuar Group! glacial deposits widespread (~750-635 Ma-- low latitudes!!). Could there have been a snowball Earth? or several episodes? One cap carbonate dates to 635 Ma in several places on the planet--suggesting an alkalinity event (and is used as base of Ediacaran Period). Life in Neoproterozoic: becoming more complex...vase-shaped microfossils at 750 Ma, Ediacaran fossils--575 Ma--significance Small Shelly Fossils (Cloudina)--548-542ish. Index fossil for the almost Cambrian Bammo---trace fossils, archeocyaths....you are in the Phanerozoic! What makes the Phanerozoic so different? three types of plate margins! Laurentia and how it changes through the Paleozoic (coarse scale)--becomes Laurasia! Pangea!! Cratonic sequences indicating epeiric seas (widespread shallow seas covering continents)—i.e., Sloss sequences--How much time do they represent? What caused these rises and falls of sea level? Grand Canyon classic sequence to show a cratonic (Sloss) sequence (Tonto Group) Reefs become important in early-mid Paleozoic time. What is a reef? Appalachian and Ouachita mobile belts—evidence in rock record The Antler Orogeny Iapetus Ocean closure Ancestral Rocky Mountains the theory of continental drift and supporting data sets Paleomagnetism and polar wandering Glossopteris flora, Mesosaurus, Lystrosaurus, Cynognathus Paleozoic Era: Cambrian explosion, trilobites, brachiopods, echinoderms, proto-chordates Burgess Shale Ordovician--high acritarch diversity, reef builders are bryozoans and corals, brachiopods, conodonts, graptolites, non-vascular plants evolve, huge mass extinction at end of period Siluro-Devonian-- gymnosperms, coral reefs, armored fish and sharks, oldest amphibians, another mass extinction and glaciation near end Devonian Carboniferous-Permian--crinoids galore, seas regressing, fusilinids, oldest reptiles, amniotic egg, P-T extinction Mesozoic--Age of reptiles! Break up of Pangea! Which continents move where throughout Mesozoic Global and North American views of plate tectonics Tethys Sea is a big global climate regulator (keeps poles warmer)western North America is now active (Cordilleran mobile belt) and eastern NA passive Atlantic Ocean started to open in Triassic time, restricted rift basins, evaporites Australia and Antartica finally split and move southward by Cretaceous time Cretaceous--high rates of seafloor spreading and hence sea-level rise! Mancos Shale Pangea pole-to-pole configuration Hot and arid in middle of large continents or supercontinents How are hot, dry, cool, wet climates generated? What can the rock record tell us about paleoclimate? Think of some examples...Navajo Ss Cordilleran mobile belt is active throughout Mesozoic and many island arcs are accreted. Sevier orogeny relative to modern geography of west Jurassic and Cretaceous interior seaways inundating foreland basin areas of NA. Mesozoic stratigraphy of the Colorado Plateau The P-Tr and the K-T extinctions dead: trilobites, rugosan and tabulate corals, armoured fish.. alive: cephalopods bivalves, gastropods, new corals (scleractinians), forams (also great index fossils), coccolithophorids (make chalk!), diatoms (make diatomite), dianoflagellates gymnosperms doing well, angiosperms arise in Cretacsous and takeover (why?): sharks and bony fish (especially the latter) reptiles--stem from Mississippian, one lineage gave rise to crocs, flying reptiles, dinosaurs, birds Dinosaurs! lived for 185 Mys! Well adapted, diverse, widespread, active, cared for young, bird-hipped (e.g., ankylosaurs, stegosaurs, triceratops, duck-billed) lizard-hipped--theropods (e.g., Tyranosaurus) and sauropods (biggies with long necks, herbivores) warm blooded? not conclusive. not all were, and some were maybe both flying reptiles, marine reptiles, terrestrial reptiles Archeopteryx--important transitional fossil, contains both bird and reptilian features, Jurassic Mammals: waiting to pounce, small, nice transitional fossil (cynodonts) main hypothesis for KT and evidence other possible mechanisms: climate change, deccan traps (flood basalts Cenozoic timescale: work in progress--Palegene and Neogene vs Tertiary and Quaternary. Quaternary may be redefined to include part of the Pliocene (based on glacial records of NA). Global Cenozoic tectonic events NA tectonic events: Laramide Orogeny followed by Basin and Range in western NA. Many volcanic events throughout Cenozoic in western NA, e.g., Yellowstone hotspot Overall cooler since Miocene globally North hemisphere glaciation--30% of conts covered in ice, up to 3 km thick! Lake Bonneville e.g., pluvial lakes Continental and deep-ocean records for Pleistocene glaciations Sea level—how low in Pleistocene? How high can it get? Cause of Pleistocene glaciations? Milankovich theory Mammals, got big, Pleistocene extinction of megafauna at 10ka Evolution of marine mammals,