Lagoonal Evaporite Formation

Two depositional types

1) Lake / Completely Enclosed Basin

2) Restricted Basin

with near permanent connection to open sea

bullseye precipitation
pattern

tear-drop precipitation
pattern

  1. Seawater becomes landlocked
  1. Precipitation of standing water body (with evaporation)
  1. Carbonate precipitation near the sea = abundant i.e. ooids
  1. Evaporite facies form bullseye
  • Carbonates around edge (precipitate easiest)
  • Gypsum layer
  • Halite (last to precipitate in centre)
  1. Porous barrier - allows seawater to leach into circular water body

Seawater leaks into basin

  1. Gypsum deposit in central basin
  1. Halite precipitates in most distal parts only (hypersaline & away from marine influence)

2) Larnaca Salt Lake, Cyprus

Coastal evaporative basin open to sea - local evaporation

1. Winter storms / surge - Water enters basin via porous sands

1) Dead Sea

Landlocked evaporative basin

2. Late summer - Salty water evaporates
--> forms thin evaporite crust halite ~ Salena

Pull-apart basin

  1. Subsided basin formed as 2 faults form an area of crustal extension
  1. Water flowed in draining the desert surrounding the basin

well below sealevel

  1. Strong evaporation due to hot arid climate
  1. Evaporites = anhydrite primarily

precipitate directly from seawater

form at ends of basin esp

Dead sea complication

Erosion older Miocene Evaporites

(included amongst base rocks )

makes water even more salty

Limited water supply

Northern river source limited

damming

overabstraction for agriculture

Water level dropping annually