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

  1. Lake envmt
  1. Palaeosol

lake dries out to form land

varve/laminite suggests lake w seasonal productivity pulse

  1. Conglomerate

Delta builds out into lake

Pissouri
Lithologies

  1. Laminated sand

seasonal cycles in lake envmt w changing runoff/sed inputs

  1. Palaeosol

lake dried out to form landmass?

  1. 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

  1. 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