Figures 1 and 2

	Figure 1. Rhodiani Area: Geographic position of the study area in West Macedonia, Greece.
	Figure 2. Geographic position of the study area in west-central Crete, southern Greece, eastern Mediterranean Sea.

 

Rhodiani Area, West Macedonia, Greece 

Figures 3-4

Figure 3. A. Geological map of Vourinos ophiolitic complex in relation to the Rhodiani area. B. Geological map of the Rhodiani area. C. Interpretive tectono-stratigraphic column. A. (1) Triassic-Jurassic carbonates (Pelagonian Marble); (2) tectonic melange; (3) dunite and harzburgite; (4) gabbro and diorite; (5) effusive and hypabyssal rocks; (6) Upper Jurassic to Upper Cretaceous limestone. B & C: (1) Pelagonian marble; (2) volcanic-sedimentary melange; (3) ultramafic tectonic unit; (3a) serpentinized and banded ultramafic mylonite; (3b) mainly harzburgite and dunite; (3c) brecciated dunite; (3d) chromitite pods; (4) Albian-Cenomanian calcarenite; (5) volcanic tectonic unit; (Sa) sheeted dolerite complex; (b) pillow lava with boninitic dyke and red chert ; (6) Upper Jurassic limestone; (13) bauxite horizon; (7) Cretaceous limestone; (7a) conglomerate limestone; (7b) bioclastic and debris flow limestone; (7c) pelagic limestone; (8) Upper Maastrichtian flysch; (9) molasse formation; (l0a) Neogene and Quaternary deposits; (l0b) Quaternary talus cone and scree; (f) thrust; (d) detachment fault; (f) fault.

Figure 4. Center. Lithostratigraphic section of Leukopighi area. (1)Pillow-lava with chert of the ophiolitic unit; (2) & (3) Upper Jurassic recrystallized limestone and calcarenite; (4) Lower Cretaceous limestone breccia and conglomerate; (5) & (6) Middle-Upper Cretaceous coarser grained bioclastic limestone and debris flow sequences rich in rudist bivalves fragments; (7) Santonian to Middle Maastrichtian bedded pelagic limestone; (8) Upper Maastrichtian pelitic flysch successions; (D) disconformity and bauxite horizon; (t)thrust. Left. Photomicrographs of Upper Jurassic chlorozoan limestones. (A) Hermatypic corals from well preserved coral boundstones. (B) Bioclastic floatstone with fragments of calcareous green algae, corals echinoderms, oncoids, and small benthonic foraminifera. Non-skeletal grains are also detectible. C) Rudstone with algal oncoids and fragments of calcareous green algae. (D) Bindstone with Bacinella irregularis Radoicic. Right. Photomicrographs of Upper Cretaceous foramol limestones. A) Rudstone-floatstone with rudist fragments and large benthic foraminifera (orbitolinids). Corals, calcareous green algae, and non-skeletal grains totally lacking. (B) Rudstone-floatstone with rudist fragments and large benthic foraminifera (orbitolinids) in crossed nicols. Along microstylolites bioclasts appear highly compacted. C) Poorly sorted rudstone with bioeroded and micritized rudist fragments and large benthic foraminifera. D) Pelagic foraminiferal wackestone with fragments of bioclastic packstone rich in shallow-water foramol skeletal fragments.

  

In the Rhodiani area (Figure 3), Upper Cretaceous diverse carbonate facies overlie sediments that include limestone breccias, conglomerates, and debris-flow units, which in turn overlie Upper Jurassic shallow-water carbonates.

 

Upper Cretaceous (Figure 4) 

In the Upper Cretaceous interval, fine bioclastic limestones are interbedded with coarse-grained, bioclastic limestones. Sediments are represented by mollusks (rudists)-rich limestones and large benthic foraminifera (Foramol Association). Corals, green algae, and non-skeletal grains are absent. Limestones are rudstones and floatstones, in a matrix consisting of poorly sorted, bioeroded skeletal fragments. The biota were calcite-dominated.

 

     Paleoenvironment 

Rapid evolution to open shelf domain, with gentle slope margins (ramps); shallow-water foramol skeletal debris, resulting from bioerosion of a mesotrophic/tendentiously eutrophic association, periodically contributed to hemipelagic deposition (temperate-type setting or tropical areas where water conditions (e.g., cold nutrient-rich upwelled currents) precluded the development of chlorozoan associations. Bioclastic sands, intercalated with the hemipelagic sediments are considered to have been transported periodically off-shelf by means of gravity flows, within a deepening trend (transgressive and highstands of sea level), giving rise to important phenomena of re-sedimentation. Relatively minor aggradation occurred along with a strong tendency toward progradation, with significant migration of the main depocenters. The resulting progradational wedges are composed of uncemented skeletal grainstone sheets and/or channels. This sedimentary setting differs substantially from the tropical carbonate settings, in terms of nature and mineralogy of the components, sedimentary texture. diagenetic potential, and 3-D geometries and is proved to be crucial in oil exploration.

 

     Diagenesis  

Evidence of early marine cementation is scarcely represented in an overall destructive, early diagenetic regime. Major porosity destruction and lithification occur mainly in response to chemical compaction of calcitic skeletons during moderate to deep burial.

 

Uppermost Jurassic – Lower Cretaceous 

These limestones are succeeded by calcareous breccias, whose clasts, derived from the underlying succession, are embedded in a lateritic matrix. Latest Jurassic - Early Cretaceous active tectonic events generated a complex paleotopography over large areas, including also the development of ophiolites and lateritic formation with emersion.

 

Upper Jurassic (Figure 4) 

The base of the studied carbonate succession is built-up of  Upper Jurassic bioclastic packstones/floatstones-rudstones and coral boundstones, followed by oncoidal floatstones and wackestones with green algae (Chlorozoan Association). Among the components non-skeletal grains as ooids are detectable. The mineralogy of the skeletal and non-skeletal grains was originally aragonite.

 

     Paleoenvironment 

Shallow-water carbonate shelf environment with limiting bioconstructed rims or discontinuous patch-reefs (tropical environment).

 

     Diagenesis 

Early diagenetic processes (desiccation. meteoric diagenesis. subaerial exposures (pedogenic processes).

 

Rethymnon Region, Eastern Crete, Greece 

Figures 5-6

Figure 5. Outcrop patterns of Rethymnon Formation in the Apostoli Basin in the Rethymnon region.

Figure 6. Left. Composite lithostratigraphic column of the sedimentary fill (Neogene carbonate sediments) of Apostoli Basin. Right. Photomicrographs of the Rethymnon Limestones. A,B. Rhodalgal-type lithofacies. C,D. Echinofor-type lithofacies. (A) Rhodalgal-type lithofacies. Floatstone with coralline algae in the form of in-situ developed rhodoliths. Rhodoliths are characterized by concentric structure. On the right is an abraded fragment of coralline algae. The matrix is a bioclastic packstone rich in benthic foraminifers, echinoderms, and fragments of coralline algae. (B) Bryozoan partially encrusted by coralline algae. Intraparticle pores are surrounded by a thin generation of scalenoedric cement, the remaining space remained open or filled by blocky cement. (C) Echinofor-type lithofacies. Floatstone (bio-micrudite) with abundant echinoderms and large benthic foraminifers. Coralline algae occur as well. (D) Floatstone (biomicrudite) with abundant large benthic foraminifers (Heterostegina sp.) dispersed in a bioclastic matrix rich in small benthic foraminifers and echinoderms. Large benthic foraminifers show a tendency toward parallel orientation.

Two Neogene basins occur in the Rethymnon region (Figure 5): (1) Rethymnon Basin to the north and (2) Apostoli Basin to the south. Elevated pre-Neogene terrane separates these basins. 

Most of the Neogene sediments filling the Apostoli Basin, in the central-west part of Crete, were deposited in terrestrial to shallow marine environments. Rethymnon Formation consists of alternating bioclastic limestones with marls. Rethymnon limestones correspond to a typical non-tropical carbonate lithofacies. They consist of: (i) Rhodalgal-type lithofacies (Figure 6 A, B) and (ii) an Echinofor-type lithofacies (Figure 6 C, D).

 

Apostoli Basin 

The Apostoli Basin consists of three principal formations:

• The Pandanassa Formation (Facies Sequence A) generally consists of alluvial fan and floodplain deposits (debris flow and braided-stream conglomerates).

• The Apostoli Formation (Facies Sequence B) consists of marine deposits (upper shoreface sandstones, Heterostegina sands, and grey-bluish fossiliferous marine marls).

• The Rethymnon Formation (Facies Sequence C) consists of alternating bioclastic limestones with marls.

 

     Depositional environment 

The Miocene Rethymnon bioclastic carbonates formed on a gentle shallow ramp; they possess many similarities with the recent bioclastic sediments of the circa-littoral bottoms of the Mediterranean Sea.