Evaporites_ Plate Tectonics and

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					       EVAPORITE
 STRATIGRAPHIC SIGNALS
 OF BASE LEVEL CHANGE
IN THE GEOLOGIC RECORD

     Christopher G. St. C. Kendall
         Geological Sciences,
 Univ of South Carolina, Columbia, SC
           kendall@sc.edu
   PRESENTATION OUTLINE
Interpretation of stratigraphic sections is often
based on the use of surfaces to subdivide the
section – namely “Sequence Stratigraphy”
If constrained by time & depositional setting the
bounding surfaces of evaporites form distinct &
widespread stratigraphic markers
    Updipsupratidal sabkha evaporite cycles
    Downdip restricted playas & basin evaporites

Unique & strong ties exist and constrain the
timing of the accumulation linear belts of marine
& lacustrian evaporites when arid climates &
plate tectonic setting coincide
         Sequence Stratigraphic
             Interpretation
  The subdivision of sedimentary section by time
significant & widespread surfaces that record
sharp changes in sedimentary character, erosion
and/or non-deposition e.g.:
  Maximum flooding surfaces (time of maximum
      transgression)
  Transgressive surfaces (first significant flooding
      surface of a sequence)
  Sequence boundaries (significant erosional
      unconformiy produced by fall in sea level)
Bounding Surfaces of Evaporites
Distinct & widespread stratigraphic markers
 constrained by time & depositional setting:
 Updip supratidal sabkha evaporite cycles
 (upper bounding surface preserved in
 regressive coastlines matching sea level
 position of the late high stand system tract)
  Downdip restricted playas & basin
 evaporites (upper surface coincides with
 sea level position of the lowstand and
 following transgressive system tract)
Updip Supratidal Sabkha Cycles
Regressive coastlines match the sea level
position of the late Highstand SystemTract
Matrix rich
Circumscribe depositional basin
Interbedded facies include:-
 Up dip - Wadii sediments & aeolian sand
 Down dip - Cycles of shallow water carbonate
 Evaporites – sometimes signaled by solution
              breccias
      Examples: Modern of UAE
                Ancient of Permian Basin
                               52oE                                          54oE                                            56oE
                                                                                                I R A N
       N


                                                                                                                                       MASANDAM
                            Wind direction of                                                                                          PENINSULA
                               “Shamal”




26oN


                                                                                                                    Ras Al
                                                                                                                  Khaimah                          GULF OF
                                                                                                                                                    OMAN



                                                                                                                                             Fujairah
                                                                                                          Dubai
       QATAR




                                                                                                 Ras
                                                                                             Ghanada
                    Jabal
                    Odaid
                                                                                       ABU
                                                                                     DHABI




                                                Jabal Dhanna                                                       Al Ain



24oN



                                                                                                                                    OMAN
                                                                     Central Coast
            SAUDI                     Western Coast
           ARABIA

                                                               UNITED ARAB EMIRATES




                                                                                                                                     50 km




Major coastal provinces of the United Arab Emirates and the bathymetry of the Southern
    Arabian Gulf in fathoms (modified from Purser, 1973).
      Western Coast of the United Arab Emirates




Western Coastal Margin of the United Arab Emirates
                      High Intertidal
                      Cyanobacterial    Intertidal
                          Flats         Carbonate
                                          Flats
 Earlier High
Energy Beaches



                 Supratidal
                  Sabkha
                 Evaporites
    Ptygmatic
    Anhydrite         Diapiric
& Storm Washover    Anhydrite
                   After Gypsum




Upper Intertidal
 Cyanobacteria
     Mats
Deflation
Surface of
 Aeolian
Carbonate
 Sabkha
Sediments     Basin
             Margin
            Carbonates
Upper Tidal
Flat Dolomite

          Sabkha of the “Guadalupian”
        Permian Seven Rivers Formation,
        of the Seven Rivers Embayment,
   Supratidal     New Mexico.
    Gypsum

        Windblown
       & Fluvial Silts
              Collapse Breccia in the Seven
             Rivers Formation Dark Canyon,
                      New Mexico.


 Upper
Tidal Flat    Collapse
Dolomites      after
             Evaporites
              Upper
             tidal flat
             dolomites


 Basinal
evaporites
  Restricted Playas & Basin
          Evaporites
Match sea level of Lowstand and
Transgressive System Tract
Matrix poor
Deeper parts of the isolated evaporite
basin
Extensive bodies
Thin interbedded fabric reflects seasonal
evaporative cycles of circum basin climate
Dead Sea
Light layers
    are
 Gypsum




  Dark layers
     are
   Dolomite
Evaporites as Time Markers


               Hierarchical classification
               of climate drivers,
               with temporal scale of
               operation (vertical axis)
               and relative temperature
               change effected at
               each ordinal scale
               (horizontal axis).

               [after Gehard et al (2001)]
  Evaporites as Time Markers
Unique & strong ties exist & constrain
the timing of evaporite accumulations.
These linear belts of marine &
lacustrian evaporites coincide with:
      Arid climates
      Plate tectonic setting
      Origin of Evaporites
Lack of rainfall
Rain shadow
   Width of continent
   High mountains
Air System of the Arid Tropics
    Where & when do thick
    evaporites accumulate?
 Lacustrian and Marine settings
 adjacent to continental plate margins
 during:-
 Break up of continental plates
 Collision & compression of continental
 plates
 Generation of structural & depositional
 barriers
Commonly within Air System of Arid Tropics
   Arid Climates Common in
         Earth History

Examples/Evidence:
 Evaporites of Mesozoic to Tertiary of
 Middle East; Paleozoic & Mesozoic the
 USA, Europe & Middle East
 Arid Climates Common in
       Earth History

Evidenced by:-
Salt Flat Evaporites
Arid Coastline Evaporites
Isolated Marine & Lacustrian
  Evaporite Basins
Eolian sediments
 Evaporite generation during
   break up of continental
            plates
Isolated linear belts of interior drainage.
Linear belts connected by restricted
entrance to the sea.
Regional drainage tends to flow away from
   break up margin
Air system of the arid tropics
Wide envelope of surrounding continents.
 Break Up Margin Evaporites
   Mesozoic of Northern Atlantic


Isolated linear belts of interior drainage.
Linear belts connected by restricted
entrance to the sea.
Regional drainage tends to flow away from
break up margin
Air system of the arid tropics
Wide envelope of surrounding continents
               Restricted
               Entrances
                To Sea
                             Regional
                             Drainage
                               Away
                            From Margin



Arid Tropics Air System
    Wide Envelope of surrounding continents
 Examples of Evaporites at
    Break Up Margins
Mesozoic of Northern Gulf of Mexico
Mesozoic of North & South Atlantic
margins
Mesozoic of Yemen rift belt
Mesozoic & Tertiary of Eritrea
East African Rift
Dead Sea
Continental Collision Evaporites

  Isolated linear belts of interior drainage.
  Linear belts connected by restricted
  entrance to the sea.
  Regional drainage tends to flow into basin
  Air system of the arid tropics
  Wide envelope of surrounding continents.
 Example of Evaporites at
    Collision Margin
  Current Arabian Gulf & underlying
      Late Mesozoic to Tertiary

Isolated linear belts of interior drainage
Linear belts connected by restricted
entrance to sea
Regional drainage tends to flow into basin
Air system of the arid tropics
Wide envelope of surrounding continents
                   Regional
                   Drainage        Restricted
                   Into Basin      Entrance
                                    To Sea


Isolated linear
Belt of interior
   drainage


 Arid Tropics Air System
       Wide Envelope of surrounding continents
  Examples of Evaporites at
     Collision Margins
Current Arabian Gulf & underlying Late
Mesozoic to Tertiary
Silurian of Michigan Basin & Western New York
State
Devonian of Western Canada & NW USA
Permian of New Mexico & West Texas
Permian of Zechstein Basin
Mesozoic to Tertiary of southern South America
Tertiary of Mediterranean
Mesozoic & Tertiary in final phases of Tethys
Sea
 Evaporite Generation Behind
           Barriers
Isolated linear belts of interior drainage.
Linear belts connected by restricted
entrance to the sea.
Regional drainage tends to flow into basin
Air system of the arid tropics
Wide envelope of surrounding continents.
      Examples of Evaporites
        Behind Structural &
       Depositional Barriers
Late Paleozoic to Early Mesozoic beneath Arabian
Gulf
  Permian Khuff of Saudi Arabia, UAE & Oman
  Upper Jurassic Hith Anhydrite of western UAE,
  eastern Saudi Arabia, southern Kuwait and
  western Iran
Evaporites trapped by original Hercynian horst &
block terrain at southern shore of Tethys Ocean.
Punctuated by limited access to sea & repeated
arid climatic events.
                 Restricted
                 Entrance
                  To Sea
                              Structural &
                              Depositional
Permian Khuff
                              Barrier over
 Saudi Arabia
                               Hercynian
Oman & UAE
                              Horst Blocks

  Arid Tropics Air System
     Wide Shadow from Adjacent Continents
                  Restricted
                  Entrance
                   To Sea
Upper Jurrassic                Depositional
 Saudi Arabia                  Barrier over
  Kuwait, Iran                  Hercynian
    & UAE                      Horst Blocks

    Tropical Air System !
    Wide Shadow from Adjacent Continents
      Examples of Evaporites
        Behind Structural &
       Depositional Barriers
  Late Paleozoic to Early Mesozoic beneath
  Arabian Gulf
  Cretaceous Ferry Lake Anhydrite of
  Florida
Evaporites trapped by structure and
depositional barrier.
Punctuated by limited access to sea &
repeated arid climatic events.
               Conclusions
Arid climates common through earth history
Arid climates signaled by thick sections of evaporites in
marine & lacustrian settings adjacent to margins of
recently pulled apart continental plates &/or in
compressional terrains of colliding margins
Arid climates punctuate geologic column & so provide
time markers
Evaporites form stratigraphic marker horizons
&“sequence stratigraphy” of a section & their bounding
surfaces can be used to subdivide this, namely:
 Upper surfaces of updip supratidal sabkha evaporite
   cycles
 Upper surfaces of downdip restricted playas & basin
   evaporites

				
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