earth history geol 2110
DESCRIPTION
Earth History GEOL 2110. The Mesozoic Era Geologic and Tectonic History of the North American Cordilleran. Major Concepts. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/1.jpg)
Earth History GEOL 2110
The Mesozoic EraGeologic and Tectonic History of the
North American Cordilleran
![Page 2: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/2.jpg)
Major Concepts• The geologic history of Cordilleran Orogen of North
America during the Mesozoic Era was dominated compressional tectonics that accreted exotic terranes in the early Mesozoic (Triassic and early Jurassic periods) and then became Andean-type volcanic arc in the mid- to late Mesozoic (Jurassic and Cretaceous periods).
• A flattening out of subduction in the Cretaceous is thought to squelch volcanism in the central part of the western US and bring about a basin and range-type tectonism called the Laramide Orogeny
• A major transgression in the Cretaceous created a Great Interior Seaway where great accumulation of marine and non-marine sediment were deposited in the Great Plains
![Page 3: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/3.jpg)
Events of the Mesozoic Era
![Page 4: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/4.jpg)
Accumulation of Thick Cambrian Sediments on the Rifted Western Margin of Laurentia
Belt Supergroup sediments preserved in rift grabens (aulocogens)
![Page 5: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/5.jpg)
Late Devonian-Mississippian Antler OrogenyAccretion of a Volcanic Island Arc
Sediments Shed off the Antler Orogen
![Page 6: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/6.jpg)
The Ancestral Rocky MountainsPennsylvanian-Permian Cratonic Warping
![Page 7: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/7.jpg)
Penn-Perm Ouchita Orogen Extension of the Appalacian Orogen
![Page 8: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/8.jpg)
Tectonic Grain of Vergence shifts in
the Mesozoic
Mesozoic Vergence
Paleozoic Vergence
![Page 9: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/9.jpg)
Triassic Accretion of Suspect Terranes Collage Tectonics
Six Major Suspect Terranes2 mostly Paleozoic3 Late Paleozoic- Early Mesozoic1 mostly Mesozoic
Wrangellia – oceanic ridge system
Sonoma/Stikinia – volcanic arcs
![Page 10: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/10.jpg)
Evidence for Suspect TerranesPaleomagnetic Latitudes Reconstructions and Tethyan Fossil
Assemblages
Many terranes contain fossils that suggest a source from the Tethys Sea
![Page 11: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/11.jpg)
Timing of Suspect Terranes Vergence
Cont, TerA and TerB all have unique paleopole orienations Cover Sed I contains pebbles from Cont and Ter B onlyCover Sed II contains pebbles from all terranes and late intrusionsAge of granites sets upper age of vergence of TerA and TerB
![Page 12: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/12.jpg)
Late Triassic Transition to Andean-type Margin
Antler Orogeny
Sonoman Orogeny
Navajo Sandstone
Sierran Orogeny
Accretion of Suspect/Exotic Terranes and Volcanic Arcs
![Page 13: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/13.jpg)
Continental Volcanic Arc
![Page 14: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/14.jpg)
Forearc EnvironmentAccretionary Wedge - material scraped
off descending slab Melange – complex mix of rock types –
ophiolites and deep water sedimentsForearc basin – filled with immature
graywacke turbidites
![Page 15: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/15.jpg)
Forearc Rock Types
Great Valley Greywackes
Blueschist (Hi-P metamorphic rx)Franciscan Melange
Pillowed Basalts
![Page 16: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/16.jpg)
Magmatic Arc EnvironmentGranite Batholiths – Feeders to Stratovolcanoes
Mt Jefferson
![Page 17: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/17.jpg)
Foreland Basin Environment
Clastic Wedge Sedimentation
Alluvial Fan Conglomerates= Molasse
Deep water muds= Flysche
![Page 18: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/18.jpg)
Sevier Orogeny Intense Compression in the Late Cretaceous (~80 Ma)
results in Crustal Thickening by Overthrusting
Devonian
Triassic Sentinal Mtns, British Columbia
Thrust Fault
![Page 19: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/19.jpg)
Laramide Orogeny Uplifted Blocks of Precambrian Crust
Latest Cretaceous – Eocene (65-35 Ma)
![Page 20: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/20.jpg)
Laramide Orogeny Magmatic Null Zone – Shallow Slab Subduction
![Page 21: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/21.jpg)
Magmatic Nulls in the Andean Continental Arc
Gaps in volcanic activity• shallow subduction• overthickened slab
Winter (2011)
![Page 22: Earth History GEOL 2110](https://reader036.vdocument.in/reader036/viewer/2022081502/56816421550346895dd5e1ff/html5/thumbnails/22.jpg)
Next Lecture
Cretaceous Trangression And Mesozoic Life