Relationships between the Terranes
Regional Geology of South West Cyprus
The Eastern Ayia Varvara Valley
The Northern Zone.
The Southern Zone
The Middle Zone.
This report is an account of field work undertaken in Cyprus in May and June 1998, in conjunction with the Department of Earth Sciences of the University of Hong Kong's Summer Field Camp to Cyprus.
An area in south west Cyprus, close to the town of Paphos, was studied and mapped over a period of nine days from 27 May to 4 June inclusive. One day was spent as an orientation and overview of the mapping area, while eight days were spent in small groups mapping a detailed area.
The report summarises the regional geology of south west Cyprus and discusses the
geology of the field area as a whole and the detailed geology of the individual mapping
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Cyprus (fig. 1) is the third largest island in the Mediterranean and is situated at the eastern end of the Sea, close to the countries of Turkey, Lebanon and Israel. The island is popular with tourists for its good climate, clean beaches, nature trails, mountains, history, ancient ruins and cuisine, and for its accessibility and the multilingual skills of the Cypriot residents. The island has a long history of political turmoil, and in 1974 the northern part of the island was occupied by Turkey.
Fig. 1: Map of Cyprus
The Troodos mountain range, with a series of peaks reaching a height of 1952m, runs through the centre of the island in a slightly NE-SW direction and, except at the southern end of the range, divides the western coastal area from the plains to the east. These three geographical areas form three of the four main geological units of the island that are discussed in this report, the fourth being the Kyrenia Range that forms the north eastern part of the island.
The three geological units that are discussed here are the Troodos Terrane, an ophiolite complex which forms the Troodos mountain Range, the Mamonia Complex which forms the area to the west of Troodos and the Circum Troodos Sedimentary Succession, which forms the area to the east, south and southwest of the Troodos Ophiolite.
The Troodos Terrane is one of the best preserved ophiolite complexes in the world and consists of a series of well preserved sequences. Those that appear in the south west Cyprus area are
The Mamonia Terrane rocks have three main lithologies:
1. The Dhiarizos Group consisting of Middle Cretaceous to Middle Triassic rocks of the
2. The Ayios Photios Group, consisting of Middle Cretaceous to Middle Triassic rocks of the
3. The Ayia Varvara Formation of Upper Cretaceous age with amphibolite grade metavolcanics and marbles derived from the Dhiarizos Group.
The Circum Troodos Sedimentary Succession has the following lithologies exposed in south west Cyprus.
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The plate collision between the Troodos microplate and the continental margin of the African plate occurred at a subduction zone where the southern continental plate subducted under the northern Troodos microplate, subsequently forming what is now known as the Troodos Massif in central Cyprus.
It is widely accepted that the Mamonia volcanic and sediments occurred as an accretionary melange in the arc system at the subduction zone. The geology in this complex forms the lower part of the accretionary arc system, compared with the East Coast accretionary terrane in New Zealand, which is the upper part of an accretionary system (I. Smith, pers. comm).
There has been much debate in the literature over the origin and emplacement of Troodos and its relationship with the Mamonia Terrance, especially where the rocks of Troodos appear in the middle of the Mamonia quite a distance away from the Troodos massif itself.
One of the theories is explained in the writing of Robertson and Xenophontos (1993) who have produced a diagrammatic thrust model of the juxtaposing Troodos and Mamonia units.
|They propose (fig. 2) that
(i) Collision of the Troodos microplate and African continental plate resulted in a subduction to the North of the continental plate and the uplift of the Troodos massif.
(ii) The Mamonia lavas and sediments that had accrued in the accretionary trench then thrust on top of the inferred Troodos basement.
(iii) Further movement of the Troodos micro-plate over the continental plate resulted in an upthrust (or backthrust) of the Troodos through the middle of the now overlying Mamonia Terrane.
Fig. 2. Model of Robertson & Xenophontos (1993)
As the same time as this event was taking place, the Troodos plate was rotating,
resulting in the arctuate lineation of the thrust zone from the Troodos massif to the
southwest of Cyprus.
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Regional Geology of South West Cyprus
On the main road from Limassol to Paphos at Petra Tou Romiou Bay (fig. 3), many of the rocks that make up the geology of this area are exposed.
Here, the road makes its way down the hill through Miocene Chalks while in the distance to the north Holocene and Pliocene-Pleistocene sands and gravel lie atop the chalk. The chalks are interbedded with clay marls of deep-water deposition. These rocks make up most of the coastal geology of the Paphos district along with calcarenite sands and gravels.
In Petra tou Romiou Bay itself are the rocks of the Dhiarizos Group. Partially crystallised, reefoidal limestone breccia occur as large detached blocks forming small islands on the edge of, or just a few metres off-shore. Their white colour contrasts well with the blue of the Mediterranean Sea. Adjacent to these blocks, also known as "knockers", at the eastern end of the bay are outcrops of massive and pillow type lavas. These lava are associated with the limestone blocks and also with deep-water, cherty type, sediments and melanges.
Fig 3: Petra Tou Romiou Bay. This photograph, taken from the road at the top of the hill is looking to the west. The "knockers" of reef limestone form small islands (a) adjacent to or just off the shore. The southern-most (left-most) "knocker" (a-a) is reputed to be the rock from which Aphrodite arose from the sea. The dark outcrop forming a promontory dividing the bay (b), is Mamonia pillow lavas. In the immediate foreground at the bottom right of the picture (c) are Miocene chalk cliffs, while the hillside rising to the north (d) has the youngest rocks in the area - Pliocene-Pleistocene gravels - sitting on top of the chalk.
Apart from the exposures at Petra Tou Romiou Bay, the Mamonia rocks are mainly found
inland from the coastal area where they are cut by a SW - NE suture zone of Troodos-type
rock of Upper Cretaceous age, consisting of serpentinite, gabbro, volcanic pillow lavas
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The field area for the Hong Kong University Group is in the hills to the east of Paphos town. It covers a total area of 12 km in an E-W direction and 3.25km in a N-S direction. Within the area, from west to east, are the villages of Ayia Varvara, Episkopi, Nata, Old Choletria, New Choletria and Phasoula. The river Esouza runs through the fertile Ayia Varvara Valley in the west, while the Diarisos River runs through the eastern area, near Phasoula.
The topography is dramatic with many hills, ridges and valleys. The highest point, to the west of Nata, was a little over 410 metres high, while the Esouza river in the nearby Ayia Varvara Valley further west was noted at about 100m a.s.l.
The land is widely used for horticulture and is particularly fertile in the two river valleys where water provides irrigation for the wide variety of fruit, eg citrus, peach, apricot, apples, figs and nuts. Grape vines are common and the composition of the soil dictates where they grow well. This in turn, aids the geological interpretation.
The geology, in general terms, has a complex suture zone of Troodos-type rocks running through the middle of the mapping area trending in a SW-NE direction. To the north of the suture zone are Ayios Photios type rocks of the Mamonia Terrane, while to the south are Dhiarizos volcanics and sediments with limestone knockers. The width of these three main zones vary within the field area from very wide, ie to the north or south boundaries, to very narrow, ie less than a metre. In the central part of the field area, near the villages of Nata and Old Choletria, the Ayios Photios and Dhiarizos zones thin out almost completely
Kathikas Melange is exposed to the north of the Ayios Photios zone, around the village of Old Choletria.
Kannaviou sediments are found outcropping in many places immediately adjacent to the suture zone, with the broadest area being at the locality of the Old Nata Village, where evidence of the instability of this bentonitic clay material is shown by many slips and ruins of buildings.
To the north of the Ayios Photios and adjacent to the Kathikas Melange and Kannaviou sediments at Old Nata, are outcrops of Miocene chalk and limestone. These may not be exposed in all the field areas depending on the width of the Ayios Photios zone in each.
Miocene chalks and more recent sediments are widely exposed south of the Dhiarizos volcanics, although not seen within all of the groups field areas due to the variable width of the pillow lava zone.
The Ayia Varvara rocks only occur in the western part of the field area on the eastern
side of the Ayia Varvara Valley. They form a wedge, that is at its broadest (about 870m)
to the east of the Esouza River, and runs for about 1.6km eastward, where it thins out
completely near the top of the valley ridge, west of Nata.
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The Eastern Ayia Varvara Valley
The lithologies are described in more detail with particular reference to the individual mapping area which is on the eastern side of the Ayia Varvara Valley, covering an area 1.25km wide in the E-W direction and 3.25km in the N-S direction. It has a topographic low in the Ayia Varvara Valley just east of the village of Episkopi, where the Esouza River cuts the NW corner of the map. The topographic high, one of three hills in the centre of the map, has a height of just over 370m. The eastern boundary of the area is west of the village of Nata. The 'new' road runs through the middle of the field area from the NE to the SW.
The lay of the topography dictated that the traverses generally commenced at points on the new road where it cut the eastern boundary. This allowed mostly downhill traverses to be made to the west, northwest, southwest and south.
The Eastern Ayia Varvara Valley is composed predominantly of three main zones. These are the Northern Zone, consisting of Mamonia Ayios Photios Group rocks; the Southern Zone consisting of Mamonia Dhiarizos Group rocks, and the Middle Zone consisting of an eastward narrowing wedge of Ayia Varvara rocks. Intermingled with the Ayia Varvara rocks, are volcanic sequences and other lithologies, believed to be of Troodos origin, forming a continuous belt on the north side of the zone and discontinuous massifs in the southern part of the zone.
The Middle Zone forms a steep contact with the northern Ayios Photios Group marked by the presence of serpentine, and a shallow contact with the southern Dhiarizos Group, marked by the presence of a fault margin.
This map area is unusual in that, although it runs the whole width, north to south, of the overall field area, there are no Miocene Chalk and limestone outcrops, nor are there any Kathikas Formation outcrops.
The Northern Zone.
This zone covers approximately half of the field area and is approximately 1.9km along the eastern boundary and 1.3km along the western boundary. The topography is steep and is at its highest point on the eastern boundary of the map where the road climbs uphill in a northerly direction. The ridges and valleys drop steeply toward the NW corner and the topographic low of the map at the Ezousa River.
The zone consists of Mamonia Terrane rocks, composed predominantly of sediments of the Ayios Photios Group. Sandstones of the Vlambouris Formation sit conformably on top of red siltstones, mudstones and radiolarian cherts with some interbedded chalky limestones of a pelagic source. The sandstone often forms ridges which culminate in rocky outcrops at the end of the ridge, whereas the siltstones lie in the valleys between these ridges. Much of the zone is covered by vegetation and there was little variation in the outcrops observed, however good examples were noted at the following map localities.
Fig 4. Outcrop at locality 29/2. A 2 to 2.5m high, fresh exposure, showing thinly bedded, alternating, red brown mudstone and chert, and white, weathered limestone. Beds vary from 2cm to 10cm wide. Hammer for scale.
The sedimentary rocks in this zone strike at an angles measured from about 260 to 290 degrees, averaging 270 degrees and dip toward the NE at about 50 to 60 degrees..
At the southern boundary of the zone, along the thrust fault of the serpentine contact with the Middle Zone, are several outcrops, up to 10 metres square in size, of limestone "knockers" from the Petra tou Romiou Formation. At the western boundary of the map, approximately mid-way along the boundary and on the contact between the Northern and Middle Zones, a larger block of limestone approximately 50m wide and 30m high was exposed (locality 3/4). Although much of the rock had been quarried, the quarry was still being worked.
The Southern Zone
The Southern Zone covers about one quarter of the map and extends south from the tar sealed road (Fig. 5) which runs traverses the map along the contact of the Southern and Middle Zones in an uphill SW - NE direction. The zone is approximately 400m wide on the western boundary and 950 wide on the eastern boundary of the map. The terrain slopes gently down toward the south and south west.
The Zone consists of Mamonia Terrane rocks of the Dhiarizos Group. Reefal limestone "knockers" of the Petra Tou Romiou Formation are associated with volcanics of the Loutra tis Afroditis and Fasoula Formations. Most of the volcanic outcrops are moderately weathered.
Fig 5. The tar-sealed road running through the middle of the field area separates the middle zone from the southern zone. This photo is taken looking to the southwest with the sea in the distance. The large hill of the left hand side of the road is the limestone "knocker" of locality 31/8. Back towards the photographer is the smaller limestone outcrop of locality 31/7. To the right are Troodos volcanic (V) and serpentinite (S) outcrops. The whitish area in the cliff is where small nodules of magnesite were found at locality 31/1.
The volcanics are well exposed on ridges and in the walls of the river valleys. Sediments of red siltstone are interbedded and exposed in the valley floors. Limestone boulders are common.
In the southwestern corner of the field area, is the remnant of a now disused pit. The material is a mud-like breccia containing small (0.5cm) clasts of red and green siltstone. East of here, close to the southern boundary, is a worked-out quarry. Many limestone fragments and chips are scattered around, and the assumption is made that a massive limestone outcrop, similar to that observed in the Northern Zone at locality 3/4, once existed.
The volcanic rocks of the Dhiarizos Group in the field area are a red-brown colour and in many places are very weathered, making it difficult to determine their nature. Generally the weathered rock made it difficult to also determine whether pillows were present, except in the fresher road-cut, exposures. However, calcite veining is common throughout. Zeolites are rare and were only found at locality 4/5 in association with a volcanic breccia overlying a flow. The zeolite was identified as laumontite (Fig. 6) by this author, based on its flat, silky fibres, up to 3cm long, forming radiating crystal groups up to 4 cm across. Well preserved pillow lavas were also found as this locality, where the brown spherical shapes, up to 0.5 metre in diameter, had variolite on the rims.
Fig 6. Samples from Locality 4/5 in the southern part of the field area. Left sample is piece of a pillow lava showing variolitic texture of the rim. Right sample shows laumontite infilling in a volcanic breccia.
Pillow lavas of a similar size were also observed on the prominent ridge running adjacent to the road on the same side but below locality 31/8.
Fresh rock was encountered at two localities: -
At locality 2/4, a basaltic rock with large vesicles filled with calcite, was found. Many of these vesicles are lenticular with one vesicle measuring 5cm in length and 1cm in width. This was the only outcrop where vesicles of this nature were observed.
While composition of the lavas in the southern area could not be determined in the field, they should be of the 'tholeitic' type lavas (Malpas et.al, 1993).
The Middle Zone.
This complex zone of the Eastern Ayia Varvara Valley covers about one quarter of the map and consists of metamorphic facies rocks of the Ayia Varvara Formation, and rocks from the Troodos Terrane. The Troodos rocks consist mainly of ultramafic serpentinite, harzburgite and volcanic rocks from the Upper and/or Lower Pillow lava series.
This zone is approximately 1500 metres wide on the western side on the mapping area, narrowing to 400m wide on the eastern side. The topography is steep and three distinct hills of about 324m, 331m and 370m, in the centre and the east of the zone, form a feature than can be seen for great distances. A fourth hill, about 350m high, is to the east just out of the field area (see also fig. 8).
The hills are composed of serpentine. A volcanic plateau separates the hills and forms much of the area between the road and the hills on the eastern side. Extending westward from the two western most hills in the centre of the zone, which lie almost directly north - south of each other, are two prominent ridges composed of serpentine. These ridges are separated by a valley of predominantly volcanic rocks, which trend downhill in a westerly direction from the plateau. This valley widens to 500m where it cuts the western boundary of the map as it heads toward the main Ayia Varvara Valley.
The northern most ridge, which forms a sharp contact with the Northern Zone, forms a steep escarpement on the southern side of the ridge.
The serpentinised rocks are greenish grey, sometimes tending to bluish grey in colour. They show characteristic smooth, soapy textures on the sheared surfaces and may be cut with veins of fibrous amphibole (chrysotile, tremolite, etc.). At locality 31/1, which is on a cut face of the southern flanks on the southern most hill, nodules of magnesite are associated with the serpentinite (see fig. 5). Harzburgite rocks, closely associated with the serpentinite, had a black, fine grained matrix, with large (av. 0.5cm) euhedral crystals of bastite which exhibited a flashy, schiller type, lustre.
The volcanic rocks of the Troodos Terrane were generally light grey in colour. Pillow shapes are common, with pillows ranging from about 30cm to 1m in diameter. The pillow structures tend to remain with weathering as the rock appears to be more resistant to the elements than that of the Dhiarizos Group. Sometimes the rock has a green-grey colour, in other places a green-pink colour. Veining around the glassy pillow selvedges is common with the veins often composed of zeolites growing from the edges to the centre of the veins, with the voids later infilled with calcite. Analcime and heulandite were observed at locality 30/2, while natrolite was observed at 3/1 Composition of the pillow lavas could not be determined in the field, but should be of the 'boninite' type (Malpas, et. al 1993).
Dykes intruding the pillow lavas and serpentinites in the sheared zones are common (fig. 7).
Gabbro was only encountered at one locality (3/2) in the valley between the two serpentine ridges, where a medium grey rock with euhedral crystals of white plagioclase up to 3mm long, was seen.
Fig. 7. A near-vertical, 0.5m wide, amphibolite dyke, intruding the highly sheared and jointed serpentinite rock near locality 30/1. The exposure is overlain by sediments composed of red silt and blocks of limestone.
On the eastern boundary of the map, where the road turns to the north, are fresh road-cut exposures. Here, the grey bentonitic clays of the Kannaviou Formation sit conformably on top of the Troodos Terrane pillow lavas. Umbers, which are remnants of black smokers, may also be seen (fig. 8).
Fig 8. A brown umber (a) and well exposed Kannaviou sediments (b) exposed in road cut. These sit conformably on top of Troodos volcanics (c). A zone of serpentinite (d) has been thrust over the top. A 'knocker' of limestone, noted as locality 30/1 on the map, sits on the northern flank of the hill. The area above (d) the to top of the hill, is just to the east of the map area.
Between the Troodos Terrane rocks and the Dhiarizos Group rocks to the south, is a large outcrop of Ayia Varvara Formation metamorphic rocks (fig. 9). These are widest on the western boundary, covering a width of 350 metres, and extending 450m westward where they are abruptly cut by a north - south trending fault. The metamorphic narrow and disappear, outcropping on the eastern boundary of the map at locality 1/1.
Two types of metamorphic rocks were observed. A light orange brown (tan) coloured mica- calcite shiest appears to be derived from the limestones of the Dhiarizos Group, while a more common greeny-black amphibolite schist with bands of plagioclase appears to be derived from the volcanics of the Dhiarizos Group.
Fig 9. Weathered amphibolite of the Ayia Varvara Formation near Locality 31/9.
On the southern boundary of this Middle Zone is a suture zone which runs roughly SW-NE. Here the amphibolites of the Ayia Varvara Formation, the Kannaviou clays of the Troodos succession and the volcanics, siltstones and limestones of the Dhiarizos Group form a complex melange, cut by a series of E-W trending thrust faults and some N-S normal faults. Pods of serpentine indicate the areas of thrust between adjacent outcrops of Dhiarizos volcanics.
Kannaviou clays were also noted adjacent to the road in the ditches on the north side.
It is possible that the road has covered an area of Kannaviou Formation clays associated
with the suture zone.
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The main structure in the field are is the SE-NE trending fault that bounds the complex suture zone running adjacent to the road throughout the middle of the field area.
The rocks in the Northern and Middle zones generally dip toward the toward the north west, striking at an average angle of 270 degrees, where-as the rocks in the Southern zone gently toward the south. Few actual strike and dips were able to be measured.
The thrusting effects of the North and Middle Zones are particularly noticeable when looking from about the middle of the eastern boundary toward the west. The two prominent serpentine ridges, in particular, exhibit slickensides and intense shearing at their sharp contact with the adjacent lithologies.
From the structure noticed at locality 2/2, where volcanics overlie the Ayia Varvara metamorphic rocks, a cross-cutting, white, foliated dyke disappears underneath the volcanics to appear again on the other side. Yet the metamorphic rocks are younger than the volcanics, so this confirms that the Southern Zone was first thrust in a north to northeast direction over the metamorphics prior to the whole complex being then thrust to the southwest back over the Dhiarizos Group rocks.
A folded and contorted sedimentary outcrop of well bedded Ayios Photios siltstone, mudstone and chert at locality 4/2 in the Northern Zone showed a 'Z' fold, which indicates thrusting in the direction of the limb between two folds, i.e. in this context in a NW - SE direction.
In summary, the sedimentary group has been thrust faulted on to the volcanics and the Mamonia Terrane has been thrust faulted on to the Troodos Terrane, juxtaposed.
The structure of the "knockers" in the Dhiarizos Group is believed to have
formed from the break-up of the limestone reefs that surrounded the island volcanics.
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The observations made in the field fit well into the framework described in the 'Relationships between the Terrane' section at the beginning of this report.
The complex zone at the southern boundary of the middle of the report needs more detailed mapping to further sort out the relationships and provide further proof to the theories of its origin.
Further investigation is required at the contact of the volcanic succession and the north side of the southern of the two ridges described from the middle zone. This author found amphibolite rock, on the southern side of the volcanic valley between the two serpentine ridges, which had not been noted from this area before.
As John Malpas said, "There are not enough rocks, but there are too many rocks. In
this area virtually every single outcrop of rock should be inspected to ascertain it
origin and help to solve the puzzle".
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Malpas J., Calon T., & Squires G. 1993. The development of a late Cretaceous microplate suture zone in SW Cyprus. In: Richard, H.M., Alabaster, T., Harris, N.B.W., & Neary, C.R. (Eds) Magmatic Processes and Plate Tectonics. Geological Society Special Publication No. 76, 177-195.
Malpas, J. & Xenophontos, C. 1987. Excursion I: Mamonia Complex and its relation to the Troodos Ophiolite. In: Xenophontos, C. & Malpas, J.G. (Eds) Field Excursion Guidebook. Troodos 87 - Ophiolites and Oceanic Lithosphere. Cyprus Geological Survey Department. p. 234-259.
Robertson, A.H.F. & Xenophontos, C. 1993. Development of concepts concerning the Troodos Ophiolite and adjacent units in Cyprus. In: Richard, H.M., Alabaster, T., Harris, N.B.W., & Neary, C.R. (Eds) Magmatic Processes and Plate Tectonics. Geological Society Special Publication No. 76, 85-119.
Geological Survey Department 1995. Geological Map of Cyprus Revised Edition, Scale
1:250,000. Ministry of Agriculture, Natural Resources and Environment.
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