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Miocene Reefal Limestones (Structural Evo SE Cyprus (Mid-Late Miocene…
Miocene Reefal Limestones
SE Cyprus Sequence
E. Miocene - Reefal lstones
Reef limestones (Pakhna) deposited atop gently dipping pelagic chalk (Lefkhara)
E. Pliocene
Marls & calcareous mudstones (Nicosia)
Basement: Breccia / ophiolitic gabbro
M. Pliocene
Chalky calcarenites, bioclastic framestones/grainstones
Reef ∆:
Reefal lstones --> calcareous algal seds
--> benthic foram grainstones
Lefkhara chalk
Structural Evo SE Cyprus
Miocene
SE Cyprus acted as
coherent structural block
= Colonised by patch reefs
Pronounced crustal extension prior to Pliocene causing E-W fracturing & tilting
Mid-Late Miocene
Reef pulled apart during chalk deposition
--> after initial (Pakhna) limestone lithification
Evidence: micritic fill of fissures
Drivers fracture: extension & growth on unstable breccia surface
End
Miocene
∴ Lstone karstification & peneplanation
Subaerial exposure during MSC
E. Pliocene
Marine transgression
∴ area was submerged
Muddy shelf evnmt (Nicosia) - Miocene lstone fissures refilled
L. Pliocene
Sea shallowed --> bioclastic carbonate deposition
Pleistocene uplift
created current outcrop
N Cyprus sequence
Basement: Upper pillow lavas ( Troodos )
Pelagic chalk (Lefkhara Fm) - laterally discontinuous
Disconformity
(u/c representing a period of erosion or non-deposition)
Mid-Late Miocene
Pakhna Formation unconformably overlies chalk
chalk
bioclastic lstone
ophiolite-derived sstone & marls
reefal lstones (Terra & Koronia)
Messinian
Kalavassos evaporites
Outcrop btwn reefal lstone to S &
topot lower Mesaoria Pliocene seds to N
Much more condensed seq --> topog high ∴ starved of cont input
Pliocene
Marl & mudstone (Nicosia) overlie Pakhna
N. Cyprus Reef
Initially: reef detritus in Pakhna Fm
Reef lstones = planar poritid bindstone
Variable alternation w packstone & chalk-marl layers
Structural Evo N Cyprus
Strong syn-depositional normal faulting control
Tortonian - fault tilting initiated Pakhna deposition
Reef location & development
Uplift of 2 main fault blokcs
Formed localised highs colonised by reefs
Seafloor topog influenced by growth faulting
Small hollows formed
into which reefal debris & volcaniclastics collected
Faulting implies
By Tortonian, N Troodos margin
emerged
undergoing erosion (mostly lavas)
Structural Evo N Cyprus
2
Messinian
Gypsum precipitated in tectonically unstable basin to N
Debris flows within evap seq
Tectonic disturbance tilted gypsum
Reefs exposed during MSC
L. Miocene
Persistent tensional faulting --> Troodos elevated
After pliocene sealevel ↑ (marine transgression)
Carbonate accumulated locally in shallow water
Reefs stop growing & pelagic carbonate deposited in deeper water
N vs S Miocene Seqs
E Miocene - E Pliocene
Sedimentation influenced by localised uplift, dominantly extensional
SE area
Remained relatively stable
Allowing substantial patch reef growth on a nr-flat seafloor
N Troodos margin
More tectonically active
∴ Large volumes reef talus
Progressive reduction fauna diversity
With ↑ shallow & turbulent waters
Porotidid corals dominate
Reef growth terminated by rapid uplift &/or the Messinian Salinity Crisis
By Late Miocene
N Troodos flank = emergent
Shed clastic Pakhna sediment into basin to N
After Messinian sealevel ↓
SE (Pliocene)
= transgressed by shallow muddy sea
N margin
Renewed tensional faulting
∴ Block rotation & redeposition of older carb/evaporites from Nicosia Fm