7.1. L. Miocene - Quaternary Transition
1. Pissouri Basin, L. Miocene
Messinian - Pliocene transition
Usually Messinian evap, then landsurface exposed
Sometime brackish conditions in L. Miocene before Pliocene
Envmt
- Lake envmt
- Palaeosol
lake dries out to form land
varve/laminite suggests lake w seasonal productivity pulse
- Conglomerate
Delta builds out into lake
Pissouri
Lithologies
- Laminated sand
seasonal cycles in lake envmt w changing runoff/sed inputs
- Palaeosol
lake dried out to form landmass?
- Conglomerate
reflooding of lake by rivers?
chalks lenses w patchy imbrication
deltaic deposit?
Faulting
Extensive normal faulting
However, upper outcrop is not --> Quaternary terrace
Late Miocene units = faulted
Pissouri Basin = fault controlled in L Miocene
Created accom space for lake?
Lake & land co-exist
varves = contemporaneous
w celestite formation
Lagomare
Plioecene ?
Climate influence ?
Wet & dry phases ∴ variable conglomerate input
Orbitally driven cllimate cycles
Extensive sequence alternating conglom-lake deposits in the region
Orbitally-driven depo Cyprus basins
Kotaphi
marls - lstones
sapropels
marine
Pissouri
Lagomare
Terrestrial
400 ka eccentricity cycle - most stable
Water input varies to cause variable conglomerate input
Post-MSC seds
- Polemi Basin L. Miocene
Big basin which nests into Polis Graben @ S end
V. thick selenitic gypsum
'Swordlike' selenite
Polemi Basin sequence
Marls --> Calcturbidites --> Selenite --> Giant selenite -(U/C)-> Pliocene
Very clean, high quality
Regular spacing btwn crystal pairs
Thick gypsum requires:
Constant shallow, stable & quiet conditions (sheltered)
Hypersaline for long periods e.g. basin margins
Possible cause: V high gypsum conc in waters
Could form rapidly
Punctuated growth = supported by white horizons within blades
Interp
Elongate, narrow embayment @ S end Polis Graben
--> Provided stable conditions for crystal growth
Elsewhere: instability/reworking limited gypsum cryst