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3.2 Troodos Cover: S Side (Sequence (2. Localised uplift --> erosion…
3.2 Troodos Cover: S Side
Miocene Channels
Tokhni Quarry
Cross bedded sandstone overlain by conglomerate
Erosional contact
Conglomerate channels cut into sandstone
Conglomerate tapers in & out as lenses
Old channel depocentre nr modern
Drainage established L Miocene & persisted to modern times
Lithologies
Bioclastic sstone
rich in shell fragments, benthic forams etc
Chalk rip-up clasts
from Oligocene chalk unit below
Rippled surfaces
palaeocurrent downslope
Conglomerate
Basalt
weathered to varying degrees
Chalk (remnant Lefkhara)
Red chert (jasper)
small pebbles - top Troodos lavas
Corals (Late Miocene=Tortonian)
Interp
Sandstone
High energy gravity driven flow
- suggested by sed structures
Sand on slope, currents take sed into channel
Channel carries sand downflow as mass flow
Conglomerate
Debris flow in channel
Both units = mass flows
MoiceneReefs on S Troodos
No evidence in-situ reefs preserved
Just transported blocks delivered
Coralline algae & benthic forams
sufficient water Z for porites to grow upwards
Shallow benthic water - need light
Sequence
All underwater
(Lefkhara chalk)
2.
Localised uplift
-->
erosion
Underthrusting as N subduction reactivates in E. Miocene
i.e. Plate above down going slab uplifted
Localised tectonic uplift on S margin
not overall cyprus uplift
Land emergent to N
3.1
Channels form & incise
into deeper Lefkhara chalk
tectonics or streams?
Chalk/chert
3.2
Fringing shelfal carbonates
in surrounding area
supply bioclastic material to channel
Evo Nested Channels
Miocene
Marls/conglomerates
Evaporites @ top so nr Messinian
Interp
Mass flow
Buoyed up v big clast
Conglomerate slid down into channel
Channel depo hiatus
Background (marl) sedimentaton covered channel
**Second
channel incised**
after period marl sediment accumulation
Second debris flow event
Hiatus
Channel cuts into marl etc etc
West palaeocurrent
= evinced by megaclast imbrication
Channels filled episodically
Likely began as shallow channel incised further
Channel cause
Tectonic uplift
?
Relating to underthrusting & uplift of Southern part of island
Slope ↑ causes rivers to incise down to retain stream power
Sealevel
?
Rivers incise down to equilibrate to base level fall
Downcutting
not
related to Messinian sealevel fall
Likely pulsed uplift
Given continued channel formation w
big clasts even in small, narrow channels
Moreover, channels do not fine upward
Pteropods
Found in marls
Dated as Miocene
Preservation unusual
Composed of unstable aragonite (shallow dissolution Z)
Signals rapid sedimentation
Protection by rapid burial
What
swimming snails
migrate daily from z to surface to hunt for food
4. Nested channel obvs
Conglomerate intermingles w planar sedimentation
Channel incised during background marl sedimentation
Moving upward, conglom lenses become thinner
River ↑ sinuous / bifurcating?
Energy change ?
Big clasts in all channels
Repeated mass flow
Need high turbulence to mobilise such large clasts
Pakhna Fm. (Miocene)