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7.2 Mammonia Succession 1 (1.1 Radiolarite (Ribbon radiolarite (Tight…
7.2
Mammonia Succession 1
Mammonia Complex
Age
L. Triassic - E. Cretaceous
Older than Troodos ophiolite
History
Subsiding passive margin Late Triassic
Early Cretaceous - Mammonia Complex
emplaced
L. Triassic/E. Cretaceous - sequence ends
∴ Mammonia = o.c. remains
1.1
Radiolarite
Below Agios Photios
Ribbon radiolarite
Thicker beds - redeposited calcturbidites
Incredibly SiO2 rich rocks
Tight chevron folds
= typical Mammonia def
'Ribbon'
cm-scale bands taper in & out like boudin
Many metres thick
Ribbon def
Abundant folds some v tight, plunging etc
Polyphase folding ?
folded folds
typical of rocks semi-lithified / nr seafloor
Folds accom by muddy layers btwn cherts
= layer-parallel slip along shaly layers
Mammonia def L. Cretaecous
--> before lithification/chalk cover
Where in deep sea are radiolarites from?
Nearer cont margin - gravity flows / turbidity currents
High productivity - inferred since radiolarian rich
Deep sea
1.2
Turbidites Sequence
Sequence
:
Sand
Radiolarite
Limestone
Interp: Turbidites
Multiple/mixed composition may reflect
turbidites of differing source area
Source:
Sand - continental
very quartz-rich
Lstone - carbonate shelf
lotsa micritic material, some shallow water bioclasts
Depo nr continental margin
: not deep ocean deposition
Sequence so far
Radiolarite (L. Triassic)
Redeposited sstone/lstone (U. Jurassic)
Akamas sandstone (E. Cretaceous)
Interp
Radiolarite
High productivity - inferred since radiolarian rich
Radiolarite seq found all around Tethys
Poss carbonate productivity not preserved (dissolved if low CCD)
Deep ocean
Turbidites
Shallower - halfway up slope ?
Sand
Appears amongst background sed gravity/tbc deposition
Slope/margin envmt?
Local land sand source nr deep ocean
Sandy mass flow down cont slope ?
Deep sea cont margin setting
--> emplaced L. Cretaceous
1.3
Akamas Sandstones
Sloping sand body
Coarse, quartz dominated & moderately sorted
What might put shallow sand in deep sea envmt ?
Gravity / mass flow of sand down continental slope
Slope / margin envmt
since local land source near deep sea