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Evidence from the Kyrenia Range, Cyprus, of the northerly active margin of the Southern Neotethys during Late Cretaceous–Early Cenozoic time

Published online by Cambridge University Press:  31 August 2011

ALASTAIR H. F. ROBERTSON*
Affiliation:
School of GeoSciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK
KEMAL TASLI
Affiliation:
Department of Geology, Mersin University, Mersin 33343, Turkey
NURDAN İNAN
Affiliation:
Department of Geology, Mersin University, Mersin 33343, Turkey
*
†Author for correspondence: Alastair.Robertson@ed.ac.uk
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Abstract

Sedimentary geology and planktonic foraminiferal biostratigraphy have shed light on the geological development of the northern, active continental margin of the Southern Neotethys in the Kyrenia Range. Following regional Triassic rifting, a carbonate platform developed during Jurassic–Cretaceous time, followed by its regional burial, deformation and greenschist-facies metamorphism. The platform was exhumed by Late Maastrichtian time and unconformably overlain by locally derived carbonate breccias, passing upwards into Upper Maastrichtian pelagic carbonates. In places, the pelagic carbonates are interbedded with sandstone turbidites derived from mixed continental, basic volcanic, neritic carbonate and pelagic lithologies. In addition, two contrasting volcanogenic sequences are exposed in the western-central Kyrenia Range, separated by a low-angle tectonic contact. The first is a thickening-upward sequence of Campanian–Lower Maastrichtian(?) pelagic carbonates, silicic tuffs, silicic lava debris flows and thick-bedded to massive rhyolitic lava flows. The second sequence comprises two intervals of basaltic extrusive rocks interbedded with pelagic carbonates. The basaltic rocks unconformably overlie the metamorphosed carbonate platform whereas no base to the silicic volcanic rocks is exposed. Additional basaltic lavas are exposed throughout the Kyrenia Range where they are dated as Late Maastrichtian and Late Paleocene–Middle Eocene in age. In our proposed tectonic model, related to northward subduction of the Southern Neotethys, the Kyrenia platform was thrust beneath a larger Tauride microcontinental unit to the north and then was rapidly exhumed prior to Late Maastrichtian time. Pelagic carbonates and sandstone turbidites of mixed, largely continental provenance then accumulated along a deeply submerged continental borderland during Late Maastrichtian time. The silicic and basaltic volcanogenic rocks erupted in adjacent areas and were later tectonically juxtaposed. The Campanian–Early Maastrichtian(?) silicic volcanism reflects continental margin-type arc magmatism. In contrast, the Upper Maastrichtian and Paleocene–Middle Eocene basaltic volcanic rocks erupted in an extensional (or transtensional) setting likely to relate to the anticlockwise rotation of the Troodos microplate.

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Copyright © Cambridge University Press 2011
Figure 0

Figure 1. Regional geological setting of the Kyrenia Range in the northern part of Cyprus. Outline map based on Baroz (1979) and Robertson & Woodcock (1986). Upper left: Simplified cross-section of the Kyrenia Range, modified from Baroz (1979) and Robertson & Woodcock (1986). Below right: Setting in the Eastern Mediterranean, showing the main sutures and the Upper Cretaceous ophiolites. Locations for which new microfossil data are given here are numbered on the map, with small boxes. 1 – Kayalar (Orga), 2 – Geçiköy (Panagra), 3 – Selvilitepe (Fourkovouno), 4 – Karşıyaka (Vassilea), 5 – Alevkaya Tepe (Kiparisso Vouno), 6 – Beylerbey (Bellapais), 7 – Değirmenlik (Kithrea), 8 – Ergenekon (Ayios Chariton), 9 – Tirmen (Trypimeni), 10 – Mallıdağ (Melounda), 11 – Çınarlı (Platani), 12 – Ağıllar (Mandes), 13 – Balalan (Platanisso).

Figure 1

Figure 2. Age, main lithologies and stratigraphy of units exposed in the Kyrenia Range. In this paper, the initially defined Greek stratigraphic names are used, with the Turkish equivalents in parentheses. Data from Henson et al. (1949), Ducloz (1972), Baroz (1979), Robertson & Woodcock (1986) and Hakyemez et al. (2000).

Figure 2

Figure 3. Field relations of the Upper Cretaceous Kiparisso Vouno (Alevkaya Tepe) Member of the Melounda (Mallıdağ) Formation, as defined here (see Fig. 2). (a) Profile of the type section on the north flank of Alevkaya Tepe (Kiparisso Vouno Mountain), in a wooded depression below the crest road. The section, which is poorly exposed, begins with tectonically brecciated crystalline limestone and dolomite (marble). The overlying unconformity is followed by a basal breccia of marble clasts in a matrix of pink pelagic carbonate. Rare clasts of calc-mylonite and calc-schist are also present. The succession continues with sandstone turbidites interbedded with shale and is then overthrust by a higher-level thrust sheet dominated by dark organic-rich, brecciated loferite-type marble of the Trypa (Tripa) Group. (bi) Sketch map showing the occurrence of calcareous sandstone and sandy limestone turbidites of the Kiparisso Vouno (Alevkaya Tepe) Member further west along the crest of the Kyrenia Range, 2.5 km east of Kornos Mountain; modified from Baroz (1979). (bii) Local cross-section showing the Upper Cretaceous transgression over the St Hilarion (Hileryon) Formation, cut by sub-vertical faults and overthrust by a higher-level thrust sheet of Hilarion marble. (biii) Log showing the Upper Cretaceous succession at map locality (bi). (ci) Sketch map (based on Baroz, 1979) showing part of the unconformity between the Hilarion (Hileryon) Formation and the Upper Cretaceous cover. (cii) Larger scale sketch map of part of the area in (ci) showing the Hilarion marble unconformably overlain by a basal breccia made up of angular to sub-angular marble clasts in a pink pelagic matrix, followed by pink pelagic carbonate and pillow basalt.

Figure 3

Figure 4. Field photographs and photomicrograph. (a) Tectonic breccia within marble of the St Hilarion (Hileryon) Formation, as commonly developed in the metamorphosed Mesozoic carbonate platform of the Kyrenia Range. Angular fragments form an interlocking jig-saw-type fabric with little or no matrix; from beneath the unconformity with the Upper Cretaceous Melounda (Mallıdağ) Formation; locality 5 on Fig. 1. (b) Irregular unconformity between thick-bedded marble of the St Hilarion (Hileryon) Formation and pink basal breccia and pelagic carbonate of the Melounda (Mallıdağ) Formation (unconformity U marked by solid line); angular clasts of marble (grey) occur just above the unconformity surface; locality 4 on Figure 1. (c) Basal breccia of the Upper Cretaceous Mallıdağ (Melounda) Formation made up of angular clasts of grey crystalline limestone (marble) in an off-white matrix of unrecrystallized pelagic carbonate containing Globotruncana sp. and other Upper Cretaceous microfossils; locality 5 on Figure 1. (d) Steeply dipping debris flow made up of mainly sub-rounded boulders of reworked rhyolite in a matrix of silicic tuff; road section 0.7 km north of Geçiköy (Panagra); locality 2 on Figure 1. (e) Outlined grain of silicic glass (isotropic) within silicic tuff. The glass includes numerous elongate gas and fluid inclusions (viewed in plane-polarized light). Abbreviations: R – rhyolite; QP – quartz phenocryst. (f) Upper Cretaceous pelagic chalk (pink) with angular to sub-angular clasts of marble (grey) derived from the Hileryon (St Hilarion) Formation. The pelagic limestone is interbedded with altered silicic tuff and includes Globotruncana sp.; from the upper part of the sequence exposed 1.5 km west of Kayalar (Orga); locality 1 on Figure 1 (see also Fig. 10).

Figure 4

Table 1. Summary of the main Upper Cretaceous species of planktonic and benthic foraminifera identified during this study, utilizing the biozonation scheme of Robaszynski & Caron (1995)

Figure 5

Figure 5. Photomicrographs of grains within sandstone turbidites of the Maastrichtian Kiparisso Vouno (Alevkaya Tepe) Member. (a) Basal breccia. Angular clasts of recrystallized limestone (marble) derived from the St Hilarion (Hileryon) Formation, with a matrix of ferruginous and calcareous siltstone; base of type section of the Kiparisso Vouno (Alevkaya Tepe) Member of the Melounda (Mallıdağ) Formation; locality 5 on Fig. 1. (b) Schist grains together with quartz, biotite, chlorite and calcite spar cement; upper level of the Kiparisso Vouno (Alevkaya Tepe) Member type section; same locality as (a). (c) Detrital grains including folded mylonite and metamorphic quartz (polycrystalline quartz) with a calcite spar cement. From calcareous sandstone turbidites interbedded with more carbonate-rich turbidites and pelagic carbonates; facies equivalent of the Kiparisso Vouno (Alevkaya Tepe) Member; locality 4 on Fig. 1. (d) Detrital grain of basalt with feldspar microphenocrysts in a mesostasis of chloritized glass; set with other detrital grains in a calcite spar cement; same locality as (c). (e) Detrital grains of radiolarian chert and metamorphic quartz within a sparse muddy matrix showing pressure solution cleavage together with a calcite spar cement; same locality as (c). (f) Detrital grains of microbial carbonate (calcareous algae) and quartz in a calcite spar cement; same locality as (c). Abbreviations: B – basalt with feldspar microphenocrysts; BI – biotite, CA – calcite cement; MA – matrix, M – mylonite (folded); MC – microbial carbonate; MI – mylonitic schist; MS – muscovite schist; MQ – metamorphic quartz (quartzite), MU – muscovite; RC – radiolarian chert; RL – recrystallized limestone (marble); Q – quartz.

Figure 6

Figure 6. Photomicrographs illustrating key age-diagnostic foraminifera from the Kyrenia Range. (a) Rugoglobigerina sp., sample 06/21b; (b) Rugoglobigerina scotti (Brönnimann), sample 06/2a; (c) Globotruncana falsostuarti Sigal, sample 06/11a; (d1, d2) Gansserina gansseri (Bolli), samples 06/11d, 3a; (e) Contusotruncana fornicata (Plummer), sample 06/11d; (f, g) Contusotruncana contusa (Cushman), samples 06/10a, 11a; (h) Abatomphalus mayaroensis (Bolli), sample 06/21b; (i) Globotruncanita stuartiformis (Dalbiez), sample 06/11d; (j) Globotruncanita stuarti (De Lapparent), sample 06/10a; (k) Globotruncana cf. bulloides Vogler, sample 06/2a; (l, m) Globanomalina pseudomenardii (Bolli), samples 06/9a, 09/39; (n) Acarinina sp., sample 09/39; (o) Morozovella sp., sample 09/39; (p) Morozovella aequa (Cushman & Renz), sample 06/9a; (q1, q2) Morozovella velascoensis (Cushman), samples 09/39, 09/24; (r1, r2) Morozovella spinulosa (Cushman), sample 06/9b; (s) Acarinina bullbrooki (Bolli), sample 06/9b; (t) Morozovella sp., sample 06/9b; (u1, u2) Globigerinatheka sp., sample 06/9b; (v) Subbotina sp. and Globigerinoides sp, sample 06/18b; (w) Orbulina sp., sample 09/23; (y) Planorbulina sp., sample 09/23. Scale bars: 0.2 mm.

Figure 7

Figure 7. Field relations of several outcrops in the central Kyrenia Range that are correlated with the Maastrichtian Kiparisso Vouno (Alevkaya Tepe) Member; 1 km east of Ayia Marina chapel, near Beylerbey (Bellapais). (a) Outline geological map of the area south of Beylerbey (Bellapais), showing the location of the stream section studied in detail. (b) Local geological sketch map of the outcrop that matches the drawing and description of Baroz (1979). Steeply dipping, nearly massive marble (Trypa (Tripa) Gp) is in thrust-fault contact with a small wedge of very altered volcanic rocks, in turn followed by siliciclastic sediments. Fine- to medium-grained sandstones at the base are overlain by fine- to medium-grained, medium-bedded micaceous sandstone (1.8 m); medium-bedded coarse sandstone (0.6 m), well-cemented massive, pebbly sandstone (1.7 m), with well-rounded pebbles of red chert, basalt and marble (< 1 cm in size), and finally by medium–coarse-grained sandstone. A 10 cm break in exposure masks a shear plane, followed by relatively deformed but well-bedded pink chalk with scattered angular clasts of altered lava and some chert (0.3 m in size). Near the base the pelagic chalk contains a thin bed (< 5 cm) of breccia/conglomerate with marble clasts, up to 1.5 cm in size.

Figure 8

Table 2. Summary of the main Cenozoic species of planktonic and benthic foraminifera identified during this study, utilizing the biozonation scheme of Sartorio & Venturini (1988)

Figure 9

Figure 8. Field relations of Upper Cretaceous volcanic and sedimentary rocks exposed near Geçiköy (Panagra) in the western Kyrenia Range (Area 2 in Fig. 1). (a) Outline geological map based on Baroz (1979), Moore (1960) and this work. The area is dominated by a recumbent SE-verging anticline of inferred Late Miocene–earliest Pliocene age. (b) Measured log of the section marked b on the map in (a). The lower part comprises well-bedded tuff with coarser and finer interbeds (< 0.5 m thick) and rare tuffaceous debris flows (clasts < 2 cm in size). The thrust plane is characterized by small duplexes of basalt entrained along the contact. (c) Local log of part of the silicic volcanogenic sequence exposed along the main road. This begins with a volcanic conglomerate with mainly sub-rounded to sub-angular boulders of hard flinty rhyolite in a pale, chaotic debris-flow unit. The sequence grades upwards into relatively massive white tuff with scatted small lava clasts. Overlying thick debris flows include angular clasts of grey flinty rhyolite clasts (up to 2.5 m in size). Interbedded fine-grained tuff contains scattered rhyolite blocks (up to 0.8 m in size). (d) Local log of basalt and pelagic chalk sequence exposed in the road section, structurally above the silicic volcanogenic sequence (see (c)). The chalk is interbedded with pillow basalt, lava breccia and hyaloclastite mixed with chalk. Chalk interbeds are dated as Late Campanian–Maastrichtian (sample 09/28) and as Late Maastrichtian (sample 06/10a, b), while pelagic limestone interbedded with pillow basalt along the road section to the south is dated as Middle Eocene (sample 09/30). (e) Part of the sequence along the north side of the main road exposes weakly bedded silicic tuff, locally overlain by a vitreous rhyolite flow. A small irregular body interpreted as a high-level basaltic intrusion cuts the tuff. (f) Pyroxenite sill intruding tuffaceous sediments. The intrusion is truncated by a thrust, above which comes a contrasting succession of Upper Cretaceous pelagic chalk and basalt. (g) The lower silicic lava/tuff sequence and the overlying Upper Cretaceous pelagic chalk/basalt sequence are separated by a thrust. Both sequences are folded into a SE-facing anticline of Late Miocene–earliest Pliocene age.

Figure 10

Figure 9. Field relations of the Upper Cretaceous volcanic and sedimentary rocks exposed near Selvilitepe (Fourkovouno) to the east of Geçiköy (Panagra); Area 3 in Figure 1. (a) Outline geological map, modified from Baroz (1979). A thrust separates silicic tuff and rhyolite below from a pillow basalt–pelagic chalk sequence above. Pillow lava and pillow breccia in the southwest of the area mapped appear to be stratigraphically inverted owing to the presence of a S-facing recumbent fold (see Fig. 8g). (b) Local profile showing the lower sequence of silicic tuffs and lenticular rhyolitic flows that are interbedded with silicic tuffs and cut by elongate sill-like basaltic intrusions. Upper Cretaceous basaltic pillow lavas and pelagic carbonates as exposed structurally above this. (c) Highest exposed part of the silicic volcanogenic rocks, overlain by silicic tuff and tuffaceous chalk, followed above a thrust plane by Upper Cretaceous pelagic chalk (pillow basalt is exposed further north). The uppermost silicic tuff beneath the thrust is brecciated, while overlying chalk just above the thrust is sheared. The thrust cuts obliquely across the tectonostratigraphy at a low angle (< 25°).

Figure 11

Figure 10. Field relations of volcanogenic rocks and pelagic carbonates exposed west of Kayalar (Orga) in the most westerly part of the western Kyrenia Range (location 1 in Fig. 1). (a) Geological sketch map based on Moore (1960), Baroz (1979) and this study. Exposure is limited on a bush-covered hillside south of the road. Basalts are interbedded with Paleocene chalk in the north (near the road) while pelagic chalk interbedded with silicic tuff higher on the hillside (southwards) is dated as Late Cretaceous, confirming the existence of the mapped thrust. (b) Profile showing the upward passage from Upper Cretaceous pelagic chalk, to silicic tuff and then into coarser volcanogenic debris flows interbedded with Upper Cretaceous pelagic chalk.

Figure 12

Figure 11. Field relations of dated chalks associated with basaltic lavas in the central and eastern Kyrenia Range, areas 7–13. See text for an explanation of each area. The locations of samples are listed in Tables A1 and A2.

Figure 13

Figure 12. Summary of the ranges of some of the age-diagnostic planktonic foraminifera identified from thin-sections during this work, associated with various volcanogenic lithologies throughout the Kyrenia Range. The main source references are indicated. The species age ranges suggest that the volcanism mainly occurred during Late Maastrichtian and Late Paleocene time. A Mid-Eocene age was recognized at only one locality. The Neogene–Recent age refers to planktonic foraminifera that were reworked into neptunian fissures and do not indicate a time of volcanism.

Figure 14

Figure 13. Plate tectonic interpretations of the Late Cretaceous tectonic development of the Kyrenia Range. Alternative 1. (1a) After spreading of oceanic lithosphere on either side of the Kyrenia platform, northward subduction initiated within the Southern Neotethys and the Troodos ophiolite formed to the south by supra-subduction zone (SSZ)-type spreading. The Mesozoic carbonate platform (Trypa (Tripa) Gp) is viewed as a Triassic-rifted continental fragment that was later re-amalgamated to a larger Tauride microcontinent to the north. (1b) Inferred oceanic crust between the Kyrenia platform and the Tauride continent was subducted northwards. (1c) The Kyrenia platform collided with the Tauride continent and was underthrust (underplated) resulting in regional greenschist-facies metamorphism. After collision the trench rolled back allowing the Kyrenia platform to rapidly exhume. (1d) With continuing subduction coupled with slab rollback, Campanian?–Maastrichtian silicic-arc-type volcanic rocks erupted, coupled with Maastrichtian basic volcanism further north. Slab rollback (potentially of two oceanic plates) accommodated anticlockwise rotation of the Troodos microplate beginning in Campanian time (see Fig. 15). Alternative 2. The Mesozoic carbonate platform (Trypa (Tripa) Gp) is viewed as the southern part of a larger Tauride microcontinent. (2a) The Southern Neotethys subducted beneath this combined microcontinent. (2b) The continent detached into upper and lower plates (perhaps failing along a Triassic rift) with the Kyrenia platform being thrust beneath the Tauride platform. The later development was similar to (1d). Alternative 1 is preferred. See text for discussion.

Figure 15

Figure 14. Interpretation of the Late Cretaceous to Late Miocene development of the Kyrenia Range following Late Cretaceous metamorphism and exhumation (see Fig. 13). (a) The silicic volcanism took place in a frontal location with basic volcanism mainly further north. The carbonate breccias were eroded locally along extensional (or transtensional) faults and interbedded with background pelagic carbonate, whereas the sandstone turbidites (Kiparisso Vouno (Alevkaya Tepe) Member) were mainly supplied from further-removed areas of the northern continental margin of the Southern Neotethys (see Fig. 15). (b) The whole of the Kyrenia Range was affected by S-directed thrusting during Middle Eocene time, which can be interpreted as an accretionary prism (work in progress). (c) Further southward thrusting took place in Late Miocene–Early Pliocene time resulting in southward thrusting over mainly Oligocene–Miocene clastic sediments (Mesarya (Mesaoria) Gp). Some of these sediments were also interleaved with the older Kyrenia Range rocks near the structural base in the south. Upper Cretaceous magmatic rocks may therefore have been more abundant than the present limited outcrop and could have been removed or concealed by later thrusting.

Figure 16

Figure 15. Plate tectonic interpretation showing the possible relation of the Kyrenia Range (Kyrenia terrane) to the anticlockwise rotation of the Troodos microplate during Late Cretaceous–Palaeogene time. Based on Robertson (1990) and Inwood et al. (2009). In an alternative tectonic model some oceanic crust still remained between the microplate and the Kyrenia margin; see text for explanation.

Figure 17

Table A1. Upper Cretaceous location data

Figure 18

Table A2. Cenozoic location data

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