PRESENTATION OUTLINE

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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
• Updip supratidal 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

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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)

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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)

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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
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Western Coastal Margin of the United Arab Emirates
Western Coast of the United Arab Emirates
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High Intertidal Cyanobacterial Flats
Intertidal Carbonate Flats
Earlier High Energy Beaches
Supratidal Sabkha Evaporites
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Ptygmatic Anhydrite Storm Washover
Diapiric Anhydrite After Gypsum
Upper Intertidal Cyanobacteria Mats
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Deflation Surface of Aeolian Carbonate
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Sabkha Sediments
Basin Margin Carbonates
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Upper Tidal Flat Dolomite
Sabkha of the Guadalupian Permian Seven Rivers
Formation, of the Seven Rivers Embayment, New
Mexico.
Supratidal Gypsum
Windblown Fluvial Silts
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Collapse Breccia in the Seven Rivers Formation
Dark Canyon, New Mexico.
Upper Tidal Flat Dolomites
Collapse after Evaporites
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Upper tidal flat dolomites
Basinal evaporites
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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

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Dead Sea
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Light layers are Gypsum
Dark layers are Dolomite
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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)
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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

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Origin of Evaporites

• Rain shadow
• Width of continent
• High mountains
• Air System of the Arid Tropics

Lack of rainfall
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Where when do thick evaporites accumulate?

• Break up of continental plates
• Collision compression of continental plates
• Generation of structural depositional barriers

Lacustrian and Marine settings adjacent to
continental plate margins during-
Commonly within Air System of Arid Tropics
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Arid Climates Common in Earth History

• Evaporites of Mesozoic to Tertiary of Middle
  East Paleozoic Mesozoic the USA, Europe
  Middle East

Examples/Evidence
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Arid Climates Common in Earth History

• Salt Flat Evaporites
• Arid Coastline Evaporites
• Isolated Marine Lacustrian Evaporite Basins
• Eolian sediments

Evidenced by-
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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.

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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

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Restricted Entrances To Sea
Isolated linear Belt of interior drainage
Regional Drainage Away From Margin
Arid Tropics Air System
Wide Envelope of surrounding continents
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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

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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.

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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

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Regional Drainage Into Basin
Restricted Entrance To Sea
Isolated linear Belt of interior drainage
Arid Tropics Air System
Wide Envelope of surrounding continents
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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

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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.

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Examples of Evaporites Behind Structural
Depositional Barriers

• Permian Khuff of Saudi Arabia, UAE Oman
• Upper Jurassic Hith Anhydrite of western UAE,
  eastern Saudi Arabia, southern Kuwait and western
  Iran

Late Paleozoic to Early Mesozoic beneath Arabian
Gulf
Evaporites trapped by original Hercynian horst
block terrain at southern shore of Tethys Ocean.
Punctuated by limited access to sea repeated
arid climatic events.
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Restricted Entrance To Sea
Structural Depositional Barrier over Hercynian
Horst Blocks
Permian Khuff Saudi Arabia Oman UAE
Arid Tropics Air System
Wide Shadow from Adjacent Continents
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Restricted Entrance To Sea
Depositional Barrier over Hercynian Horst Blocks
Upper Jurrassic Saudi Arabia Kuwait, Iran UAE
Tropical Air System !
Wide Shadow from Adjacent Continents
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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.
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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