MESOZOIC GEOLOGY

• climate => arid, seasonal monsoons
•  cosmopolitan faunas =>     Lystrosaurus on land

                                  =>     Claraia in the ocean
•  all continents connected

 Mild temperature gradient => ferns in Boreal Realm
              pervasive tropical conditions

Geologic record      Tr and Jr mostly continental, little deep sea.
                               Cr => continental and deep sea. Subduction.
 
 

Cr:
Gondwana splits               Antarctica & Australia from the rest
                                         Africa from SAm; India moves N
     _______________: Part of Gondwana left attached

     ________________ocean opens up

Impact of Sea Level, Climate and Ocean Circulation
Cr: ______________ ____________ ____________ activity => sea level rose

Hot Mid Cr =>______________________ => black shales; cooler Lt Cr, floras change
                  Poleward migration of hypersaline water
                  Slow wind driven atmospheric circulation (warmer climates)
 

MZ Geology of Eastern North America
Tr
     fault basins:               alluvial fans
                                       arkoses
Newark                          _______________ _________________ (lakes with fish)

Supergroup                    inter-layered ______________&  _______________(Palisades Sill)
 

Jr
    Carbonate shelf deposits => __________________  margin

Ea Cr
                         Siliciclastic sediments (Appalachian erosion, until today)
                         Carbonate sediments (S Fla)
 

MZ Geology of Western North America

Complex: succession of orogenies

            Tertiary                                                     Cordilleran
                                   _____________
            Cretaceous    _____________                 Orogeny (Subduction Pac Pl
                                     Nevadan      
            Jurassic                                                     under NAm Pl)

           Triassic
                                     _________________
            Permian
 
 

•   Mostly arid => _____________ _____________
•   Humid at the  sea's margins
•   Euramerican Flora in Petrified Forests
•   Chinle Formation (Lt Tr) also _____________ & amphibians
•   Jr  ___________________ (Sundance Sea)

Accretion
Sonoma Orogeny: Is arc & continent ______________ (SE OR, CA and NV)

Nevadan Orogeny:

•     Emplacement of ______________
•      Franciscan Group accretionary wedge. __________ P, ___________T metamorphism.
•     Accretion of exotic terranes from N Washington to Alaska
•     Thrusting & faulting => Sundance Sea _____________
•      Molasses from uplifted lands on the W: Morrison formation: dinosaur fauna.

Sevier Orogeny:

•     Igneous belt moves east
•     shallower angle

Mid Cretaceous Transgression

•     Mowry sea, when connected with the Gulf of Mexico = ____________ ____________ Seaway.
•    Gulf fringed by rudists, replaced by __________________ by Lt Cr

 
• Cycles of transgressions and regressions in the Seaway caused by variations in
• rate of sediment _____________,
• sea level,
• rate of __________________.

•   __________ _______________ were also abundant in Europe.

  (high MOR activity =>  Low _______/______ ratio  =>__________ precipitation = calcareous nannoplankton)

Laramide Orogeny (Lt Cr)
             Interior Seaway ___________ ( No more seas in the Western interior).