Mamonia Complex, southwest : Evolution and emplacement of a Mesozoic continental margin

A.H.F. ROBERTSON Grant Institute of Geology, West Mains Road, Edinburgh EH9 3JW, United Kingdom N. H. WOODCOCK Department of Geology, Downing Street, Cambridge CB2 3EQ, United Kingdom

ABSTRACT the eastern Mediterranean, Othris in central Greece (Hynes and others, 1972; Nisbet and Price, 1974; Smith and others, 1975; The Mamonia Complex in southwest Cyprus comprises an as- Smith and Woodcock, 1976a, 1976b) and complement the pre- semblage of Upper Triassic to Lower Cretaceous sedimentary liminary findings from the analogous Antalya Complex of south- rocks, Upper Triassic mafic igneous rocks, and subordinate west Turkey (Woodcock and Robertson, 1979). As the Mamonia metamorphic rocks, which together lie adjacent to the southwest rocks are in direct structural juxtaposition with the ophiolitic margin of the Troodos ophiolitic complex and its Upper Creta- Troodos Complex, we necessarily join the debate over the geotec- ceous sedimentary cover. tonic setting of the Troodos Massif. Particularly, we give evidence The sedimentary facies of the Mamonia Complex record the based on detailed facies analysis that the Mamonia Complex re- progressive development of a Mesozoic passive continental margin. cords the Triassic to mid-Cretaceous evolution of a passive conti- Initial crustal subsidence associated with deltaic and turbiditic ter- nental margin, which can be interpreted as part of the former mar- rigenous clastic sedimentation was followed by continental rifting gin of the Troodos ocean. Our results offer little support for recent and then the genesis of marginal oceanic crust in Late Triassic time. suggestions that the Troodos Massif was generated as a marginal Subsequent pelagic and hemipelagic deposition during Jurassic and ocean basin of Late Cretaceous age located behind an active island Early Cretaceous time reflects passive continental margin subsi- arc (Pearce, 1975; Smewing and others, 1975), or that it was dence. Shallow-water calcareous material derived from an adjacent formed in an island-arc complex (Miyashiro, 1973, 1975). In addi- carbonate platform, probably now located in southern Turkey, was tion, we present new structural data that demonstrate that the deposited on the margin by gravity flows. After initial rifting, Mamonia rocks were emplaced from the present southwest, the coarse terrigenous clastic input was minimal until a major influx of opposite sense to that determined by some previous structural terrigenous material in Early Cretaceous time, possibly contem- studies (Lapierre, 1972, 1975; Turner, 1973). Finally, implications poraneous with an episode of renewed ocean-floor spreading in the for the regional tectonic setting are considered. area. Allowing for the 90° Tertiary rotation of Cyprus, the Mamonia rocks formed part of the northern margin of a small NATURE AND STRATIGRAPHY OF ocean basin during Jurassic and Cretaceous time. The Troodos THE MAMONIA COMPLEX Complex is likely to represent a younger surviving fragment of the same basin. By Late Cretaceous time, ocean-floor spreading had The diverse and structurally complex assemblage of sedimentary, ended, followed in the Maastrichtian by disruption, folding, and igneous, and metamorphic rocks of southwest Cyprus, now at- emplacement of the Mamonia sedimentary sequences onto the tributed to the Mamonia Complex, was originally regarded as au- Troodos ophiolitic rocks. The Mamonia sedimentary rocks are tochthonous relative to the underlying ophiolitic Troodos Complex now arranged in subhorizontal sheets which, on the basis of fold (Bellamy and Jukes-Brown, 1905; Henson and others, 1949; Gass, vergence and facing directions, were emplaced toward the present 1960). According to Henson and others (1949), the strongly de- northeast — that is, prior to paleorotation, toward the original formed state of the Mamonia rocks arose from a combination of southeast. The displaced sheets probably represent down-margin syndepositional slumping, updoming by laccolithic igneous bodies, gravity slides. The evidence is compatible with both the Mamonia and subsequent high-angle faulting. By contrast, the key to our and Troodos Complexes having a local ("external") origin in con- present conception of the overall structure of southwest Cyprus trast to the currently favored "internalist" hypothesis involving was the demonstration by Lapierre (1968b, 1970) and Kluyver long-distance transport. (1969) that the Mamonia rocks form a major allochthonous struc- tural unit, distinct in origin from the autochthonous Troodos Mas- INTRODUCTION sif with its sedimentary cover. Along the southwest perimeter of the Troodos Massif, the Mamonia rocks are thrust over thick se- In the belief that sound geotectonic interpretations of ancient quences of volcaniclastic sediments, named the Forma- geologic settings in the Alpine-Mediterranean belt must be based tion by Lapierre (1968a), which rest in situ on the underlying on a combination of all available geological evidence, we here pre- Troodos Massif (see Robertson and Hudson, 1974; Ealey and sent a detailed account of the depositional evolution and later de- Knox, 1975; Robertson, 1977c, for discussion). formation of part of one particular continental margin, represented Although we mostly agree with Lapierre (1975) about the rela- by the Mamonia Complex of southwest Cyprus. Our data extend tively disorganized structural state of the Mamonia rocks and the the findings from one other well-documented continental margin in presence of bodies of Troodos-type igneous rocks, serpentinite, and

Geological Society of America Bulletin, Part I, v. 90, p. 651-665, 8 figs., July 1979, Doc. No. 90708.

651

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metamorphic rocks of uncertain origin (Gass, 1960), we disagree tou Romiou Formation. The main body of the Mamonia Complex with her over the crucial question of the emplacement direction of is overlain by discontinuous masses of melange (the Moni mélange the allochthon. Lapierre (1972, 1975), and also Turner (1973) ar- of Lapierre, 1975), now termed the mélange to avoid con- gued that the Mamonia "nappes" were rooted to the present north- fusion with the Moni mélange described earlier from the Limassol east of Troodos, on the basis of the supposedly southwestward ver- District of southern Cyprus (Pantazis, 1967). The formation of the gence (overturning) of folds in the Mamonia sediments. In contrast, Kathikas mélange postdates the main emplacement of the Kluyver (1969), Robertson and Hudson (1974), Ealey and Knox Mamonia Complex (Lapierre, 1975) and will not be discussed in (1975) and Robertson (1977b) have already argued for a generally detail here. northeastward emplacement on the basis of regional geological considerations. AYIOS PHOTIOS GROUP: The existing stratigraphic nomenclature that has evolved more or CONTINENTAL MARGIN SEDIMENTATION less ad hoc since the work of Henson and others (1949) is in the course of being systematically redefined by R. E. Swarbrick and Stratigraphical sections of the three sedimentary formations of A.H.F. Robertson (unpub.), in line with currently accepted strati- the Ayios Photios Group are shown in Figure 3 and geographically graphical convention. Figure 1 shows the new stratigraphy, togeth- located in Figure 2. Although indeterminate due to the structurally er with older terms, as employed by Lapierre (1975). The available dislocated state (see below), the total thickness of the Ayios Photios paleontological age data, which have been summarized by Ealey Group is unlikely to have originally greatly exceeded 200 m. and Knox (1975), and Cleintuar and others (1977), are also shown in Figure 1. In common with Lapierre, the new stratigraphy is Vlambouros Formation: Basal Flysch based on a subdivision of the Mamonia Complex into two separate stratigraphical groups, termed by Swarbrick and Robertson (un- Where relatively intact undeformed sequences have been found, pub.) the Ayios Photios Group, which is almost entirely sedimen- the Vlambouros Formation consists of as much as 30 m of litholog- tary, and the Dhiarizos Group, which is mostly igneous. The Ayios ically heterogeneous quartzose sandstones, siltstones, and Photios Group can be subdivided into three formations: the Vlam- mudstones, together with volumetrically subordinate occurrences bouros, the Marona, and the Episkopi, in ascending stratigraphic of calcirudites, calcarenites, and calcilutites. The following distinc- order. The Dhiarizos Group includes two suites of predominantly tive facies are recognized. basaltic igneous rocks: the Phasoula lavas, which are associated Cross-bedded Lignitic Sandstones. Grossly lenticular, medium- with the sedimentary Kholetria Member, and the Loudra tis Aph- to coarse-grained sandstones as much as 2 m thick (Fig. 3, A, sec- roditis breccias, which show a marked spatial relationship with tion 4) containing numerous partings of pyritic bituminous shales substantial masses of reef and pelagic limestones, termed the Petra have been found in the Akamas Peninsula. These sandstones range from massive to ripple to cross-laminated, occasionally with evi- dence of reverse grading. Individual beds have a variable volume of KEY LAPIERRE . 1975 THIS STUDY U= UPPER finely divided plant material. There are also occasional carbonized MAMONIA NAPPES MAMONIA COMPLEX M= MIDDLE L = LOWER MAMONIA MAMONIA AYIOS PHOTIOS logs as much as 0.6 m long. DHIARIZOS GROUP LAVAS FORMATION GROUP Thick-bedded Sandstones. Relatively coarse-grained, thickly bedded, massive sandstones crop out in several areas (for example, Fig. 3, A, section 6) as fragmentary sequences as much as 15 m thick. The individual sandstone beds range in thickness from 1.3 to 2.1 m, often with excellently developed structures diagnostic of the A—D intervals of turbidity-current—generated Bouma sequences (Bouma, 1962). Interturbidite partings (Bouma E interval) are gen- erally absent, possibly because of either nondeposition or contem- poraneous submarine erosion. Where occasionally present, the in- I terturbidite partings consist of finely laminated fine-grained silty I AKAMAS SST AKAMAS I MEMBER sandstone. Elsewhere (for example, Fig. 3, B, section 24), in con- SANDSTONES I I REEF LSTS I trast to these entirely terrigenous sediments, the sandstones are in- LST I CHERTS terbedded with calcarenites, calcilutites, and cherty calcareous BRECCIAS I siltstones, comparable with those in the overlying Episkopi Forma- I tion. M ? Medium-bedded Sandstones. Thick sequences of irregularly JURASSIC cemented medium-bedded sandstones form the most widespread sediment type of the Vlambouros Formation (for example, Fig. 3,

PETRA sections 1, 2, 3, 5, 10, 12). Characteristically, the lower parts of the MAMONIA PETRA LOUDRA TIS PHASOULA TOU HALOBIA ISTS MARONA FM U ROMTOU LAVAS TOU APHRODITIS LAVAS & + sections are gray or gray-green, whereas the higher levels are red or LSTS ROMIOU BRECCIAS KHOLETRIA LSTS MEMBER TRIASSIC - GRES A 1 VLAMBOUROS FM red-purple. All these sandstones are typically fine to medium VÉGÉTEAUX I I M grained, often graded, with alternations of more thinly bedded ar- L" gillaceous sandstones and siltstones. Many of the individual beds,

PERMIAN which are as much as 0.4 m thick, show B-D, B—E, and D-E Bouma turbidite intervals (Fig. 3, A, sections 1, 2). Bottom struc- Figure 1. Stratigraphy and paleontologically determined age of tures are numerous, particularly flute and groove casts. Elsewhere, rocks of Mamonia Complex. other sequences (Fig. 3, A, sections 10, 11, 12) show complex

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/90/7/651/3419040/i0016-7606-90-7-651.pdf by guest on 26 September 2021 Figure 2. Outline geology of southwest Cyprus, showing distribution of Mamonia Complex relative to Troodos Igneous Complex, and location of places and measured sections mentioned in text.

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amalgamated horizons of massive, vaguely graded or plane- carbonate-depositing environment (compare Carter, 1975). The laminated intervals. Some beds show evidence of soft-sediment in- much more thinly bedded sandstones in the southwest part of the stability in the form of convolute lamination and intraformational area (Khapotami River; Fig. 3, B, section 22) are seen as more distal slumping. In contrast, the thinner interbeds and partings comprise turbidites that have been extensively reworked. In some sections, pink finely laminated siltstones and massive silty calcilutites, which occasional hiatuses in sedimentation are marked by preferential are locally highly bioturbated and often partly silicified. silicification, calcite cementation, or extensive bioturbation. Thin-bedded Sandstones. Several important sequences of much more thinly bedded sandstones occur in the southwest part of the Marona Formation: Pelagic Limestones area, particularly in the Khapotami River (Fig. 3, B, section 22). The fine- to medium-grained sandstones in beds as much as 0.15 m In the southwest part of the area, the Vlambouros sedimentary thick alternate with pink and gray calcilutites and calcareous strata pass up into fragmentary sequences of relatively thickly bed- siltstones. Many of the more massive beds show C—E and D—E ded gray calcilutites, termed the Marona Formation (Fig. 1). These Bouma intervals, together with numerous flute and groove casts; are, in turn, overlain by radiolarian mudstones, radiolarites, and these are interpreted as distal turbidites. In contrast, many other siltstones, attributed to the Episkopi Formation. In contrast, in beds, which are often extensively bioturbated, show repeated low- most other areas (for example, Akamas Peninsula, Fig. 2) the angle cross-bedding and extensive evidence of current reworking. Vlambouros passes into the Episkopi sediments without a break. Thinly bedded turbiditic sandstones are also seen farther north Where present, the Marona limestones consist of possibly as (Fig. 3, B, section 25), but there these are intimately interbedded much as 20 m of weakly laminated or massive fine-grained gray with much thicker, coarser grained sandstones and calcarenites, and pink calcilutites, alternating with partings of finely laminated which are absent in the Khapotami River. shale as thick as 0.08 m. The limestones crop out widely in the upper reaches of the Dhiarizos River, particularly at the type sec- Petrography of the Vlambouros rocks tion (Fig. 3, B, section 21), which has been partly obscured by landslipping since it was first described by Lapierre (1972). At this Thin-section examination of the coarse-grained sandstones from locality, beds of calcilutite as much as 0.25 m thick contain win- the Akamas Peninsula (Fig. 3, A, section 4) reveals a fabric of pre- nowed accumulations of Halobia shells and occasional poorly dominantly angular to subangular quartz grains with vol- preserved ammonites; bioturbation and stylolitization are exten- umetrically subordinate plagioclase, orthoclase, perthite, horn- sive. Thin-section examination of the calcilutites reveals numerous blende, epidote, muscovite, and rare heavy minerals. There are also Halobia filaments and radiolaria replaced by calcite. The micritic numerous angular fragments of quartzite and mica schist, as long matrix shows incipient recrystallization to microspar. as 4 mm. These sandstones consist entirely of terrigenous clastic The Marona limestones are interpreted as relatively deep-water material, whereas many of the sandstones elsewhere contain vol- pelagic carbonates laid down on part of a continental margin, for a umetrically variable admixtures of calcareous grains derived from a shallow-water carbonate environment. Likewise, the intercalated 1 calcarenites consist mostly of redeposited algal material, ooids, pisoliths, echinoid plates, a variety of intraclasts, and some coral KEY

and benthonic foraminifera. Overall, the proportion of calcareous MAIN COLUMN SIDE COLUMN clastic sediment shows a general tendency to increase in volume upward, predominating, for example, in the highest stratigraphical sondstone • massive beds

levels in some sections (Fig. 3, A, sections 1, 2) of the Vlambouros si 1 tstone x - laminat ions Formation. In contrast, the occasional partings of pink calcilutite - - mudstone = parallel laminations noted in the field are seen to have been originally fine-grained —~ mudstone with lenticular bedding radiolarian siltstones that have been replaced almost totally by mic- _ siltstone porting» rospar during diagenesis. ll'l , 'l'l'l'I,!,1,1l rodiolarite -v channelling CD CP a> limestone conglomerate convolute la mi nations

Deposition of the Vlambouros Sediments • 0 • calcarenite I slumping

calcilutite A A she ly The terrigenous clastic sediments of the Vlambouros Formation V V V pillow lavas ? bu r rowi ng show derivation from an older low-grade psammitic metamorphic V V VV V VV vv V terrain, together with separate contribution from a shallow-water chert Upper Triassic carbonate assemblage. The cross-bedded lignitic poorly exposed sequence - mud flake

sandstones seen in the Akamas Peninsula (Fig. 3, A, section 4) re- Tr Triassic (Mn) manganiferous cord rapid shallow-water deposition, probably in a deltaic envi- Ju Jurassic (1-5) average bed thickness in ronment. In contrast, the thick-bedded texturally immature Cr Cretaceous sandstones, characterized by Bouma A—E intervals, are interpreted Colour as proximal turbidites. Many of the medium-bedded sandstones are inferred age c.f. Ealey & Knox ond Lapierre. turbiditic but probably more distal. Some of the thickest sandstones M il, black , gn ,green , G, grey ; j.j P, pink ; O, oranqe ; R , red ; age determined, v ' ® that are massive and homogeneous are likely to have been depo- e Tr -9 this study. W, white ; y, yel low . sited by submarine mass flow (compare Middleton and Hampton, Episkopi Fmn. /^Af 1973; Mutti and Ricci Lucchi, 1975), whereas some of the thinner EF Kholetria Member interbeds of calcirudite and calcarenite (Fig. 3, B, section 24) can be MF Marona Fmn. P¡_ Phcisoula Lavas interpreted as submarine grain flows derived from a shallow-water VF Vlambouros Fmn.

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time starved of terrigenous clastic input. Comparable pelagic lime- of some beds and possible dish structures, the Akamas sandstones stones crop out much more extensively in the analogous Antalya are surprisingly massive and structureless. When viewed in thin Complex of southwest Turkey (Marcoux, 1976; Woodcock and section, they are found to be closely comparable in provenance to Robertson, 1979). the sandstones of the underlying Vlambouros Formation. How- ever, texturally, the two sandstones are quite different; the Vlam- Episkopi Formation: Predominantly Hemipelagic Facies bouros are mostly poorly sorted lithic sandstones, while the Akamas sandstones are orthoquartzites marked by a strongly Throughout the entire area, the higher levels of the Ayios Photios bimodal grain size-frequency distribution. Our work also shows Group consist of a diverse assemblage of pelagic and hemipelagic that the thick-bedded sandstones are found only in sequences con- siltstones, calcilutites, radiolarian mudstones, and radiolarites, to- taining the thickest and presumably most proximal flysch in the gether with volumetrically subordinate quartzose sandstones, underlying Vlambouros Formation (for example, Ayios Photios limestone conglomerates, and calcarenites. These rocks are here area, Fig. 3, B, section 19). The Akamas sandstones are completely assigned collectively to the Episkopi Formation, which ranges in absent from the sequences dominated by the thinner and appar- age from Early Jurassic to at least mid-Cretaceous (Fig. 1). ently more distal turbidites. Notably, several thin beds of relatively Mudstones. Many of the Episkopi sequences are made up fine-grained Akamas sandstone have been seen in the highest levels mostly of a variety of finely laminated green, greenish-purple, pur- of the radiolarian mudstones stratigraphically overlying the type ple, or gray mudstones. These mudstones are especially thick in se- section of the Marona Formation (Fig. 2, B, section 21). This is quences now located close to the southwest perimeter of the additional evidence that the Marona limestones are likely to have Troodos Massif (for example, Ayios Photios area, Fig. 3, B, sec- been deposited close to a continental margin rather than in an open tions 15, 16, 17, 18). Thin sections show minute terrigenous oceanic setting. quartzose grains within a calcareous microcrystalline matrix. Calcareous Facies. A distinctive feature of the lower levels of Radiolaria are ubiquitous but always volumetrically subordinate. some sequences of the Episkopi Formation is the occurrence of Siltstones. In some sections the higher levels of the Episkopi substantial intercalations of carbonate conglomerate, associated Formation show intercalations of laterally continuous fine-grained with thinner calcirudites, calcarenites, and calcilutites within typi- white siltstones. The beds, ranging in thickness from 0.09 to 0.15 cal hemipelagic sediments of the formation. The carbonate con- m, are graded, often conspicuously cross-laminated (Fig. 3, B, sec- glomerates are particularly well developed around Episkopi itself tions 20, 21). Thin sections show mixtures of fine-grained terrigen- (Fig. 3, B, sections 12, 13, 14), in the Akamas Peninsula (Fig. 3, A, ous and calcareous clastic material, as seen in the underlying Vlam- sections 1, 2, 3) and elsewhere (Fig. 3, A, section 5). For instance, in bouros rocks (for example, Fig. 3, B, section 22). The thin graded the Episkopi area three separate carbonate horizons occur in a se- siltstones are interpreted as turbidites deposited in a deeper more quence of finely laminated siltstones, radiolarian mudstones, and distal environment than most of the Vlambouros sediments. silicified radiolarites. The lowest of these horizons comprises three Lower Sandstones. Relatively coarse-grained sandstones have amalgamated units, totaling 1.9 m thickness. Interestingly, the low- been found only in the lower part of the Episkopi Formation in est of these amalgamated units consists of repeated 10- to 20-cm- sections located close to the southwest margin of the Troodos thick partings which show grading and crude parallel laminations. Massif (for example, Ayios Photios area, Fig. 3, B, section 16). In The second calcareous horizon is comparable, but more distinctly this area, thick-bedded turbiditic sandstones of the Vlambouros lenticular over several metres along strike. The uppermost of the Formation are overlain by typical radiolarian mudstones, major carbonate horizons is by far the most substantial vol- siltstones, and calcilutites of the Episkopi Formation. Above, there umetrically and can be traced over 2.5 km along strike, where it is an approximately 10-m-thick intercalation of calcareous reaches a maximum thickness of 5.5 m. Where best exposed, this siltstones and sandstones, in beds as much as 0.2 m thick; these horizon can be seen to consist of roughly bedded calcirudite con- show diagnostic Bouma B-D and D-E turbiditic intervals. taining numerous roughly preferentially orientated clasts of cal- Upper Terrigenous Sandstones: Akamas Sandstone. The Epis- carenite and calcilutite as much as 0.25 m in diameter. There are kopi sedimentary strata show an overall tendency to become finer scattered smaller clasts of angular red chert, with occasional frag- grained, more thinly bedded, and increasingly radiolarian-rich up- ments of gray siltstone and sandstone, and disrupted lenses as much ward. However, in marked contrast, the higher levels of the Epis- as 1.8 m long of cherty mudstone similar to the underlying sedi- kopi sequences, in some sections, show a renewed major influx of ments. The matrix, where present, consists of redeposited relatively coarse quartzose sandstones. These sandstones were orig- hemipelagic sediment similar to the intercalated sediments locally. inally distinguished as the "Akamas Sandstone" (Henson and Comparable "organized" (see Mutti and Ricci Lucchi, 1975) con- others, 1949) due to their occurrence as huge isolated blocks along glomerates have also been found elsewhere, especially in the the crest of Akamas Peninsula. Subsequently, Lapierre (1975) dem- Akamas Peninsula (Fig. 3, A, sections, 1, 2). There, the conglom- onstrated that these were clearly interbedded with the "Mamonia" erates locally show marked lateral thickness variations over several sediments at several localities, particularly in the Ayios Photios area tens of metres. These conglomerates are typically silicified, and along the coast east of Loudra tis Aphroditis (Fig. 2). presumably due to an influx of silica from the surrounding Where best exposed, in the Ayios Photios area close to the radiolarian-rich sediments during diagenesis. Troodos Massif (Fig. 3, B, sections 15,16), the Akamas sandstones Some sections without calcareous conglomerates instead have in- first appear as thin gray or greenish-gray medium-grained or- tercalations of graded calcirudites and calcarenites as much as 0.5 thoquartzites in beds as much as 0.3 m thick, within finely lami- m thick (Fig. 3, A, section 3). Some other sections exhibit numerous nated radiolarian mudstones. The sandstones then thicken prog- partings of fine-grained calcarenite and calcilutite, ranging in ressively upward, culminating in major laterally continuous hori- thickness from 0.05 to 0.25 m. These beds, which are generally zons of yellow or orange orthoquartzites as much as 5 m thick. silicified, typically grade up from a cross-laminated base into a zone Apart from occasional small-scale convolute lamination at the base of red silicified calcilutite; sedimentary structures are diagnostic of

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the C-E and D-E Bouma turbidite intervals. Surprisingly, these support for this comes from the Antalya Complex of southwest turbiditic calcilutites are also found interbedded with the Akamas Turkey (Woodcock and Robertson, 1979). Factors controlling sandstones in the Ayios Photios area (Fig. 3, B, sections 15, 16). radiolarian abundance are unclear, but enhanced productivity due Comparable, but even more thinly bedded, calcilutites are also a to nutrient upwelling in an incipient ocean basin is a strong possi- conspicuous feature of the higher levels of the Khapotami River se- bility, comparable with the Gulf of California (Calvert, 1966). The quences (Fig. 3, B, section 22) in the southwest part of the area. striking abundance of manganese in the early Cretaceous interval Radiolarites. In some sequences the higher stratigraphic levels of the Episkopi sequences; may be related to a phase of adjacent of the Episkopi sediments are dominated by red or red-purple contemporaneous volcanic activity, known to have occurred at radiolarites in beds mostly 2 to 8 cm thick (Fig. 3, B, sections 20, least in the analogous Baér-Bassit area of northern Syria (Parrot, 22). In thin section, abundant Radiolaria in varying states of recrys- 1974,1977). The general tendency of all the Episkopi sediments to tallization are seen in a matrix of finely interlocking crystals of become finer grained and more thinly bedded upward has an ex- chalcedonic quartz. No evidence of a disordered cristobalite ception in the appearance of the Akamas sandstone in the Upper (opal-CT) precursor is found in these cherts (compare Robertson, Cretaceous. The textural maturity of these sandstones implies pro- 1977a), presumably due to total diagenetic conversion of biogenic longed reworking in a stable current-swept environment, probably silica to chalcedonic quartz. In general, radiolarites predominate in on a continental shelf, followed by rapid deposition into a deeper the higher levels of those sequences that lack major thick-bedded water hemipelagic environment. Significantly, the petrographical turbiditic intercalations. Abundant radiolarites are also found evidence suggests that all the quartzose sediments of southern Cy- above the Marona pelagic limestones (Fig. 3, B, section 22). Com- prus were ultimately of similar provenance. parison of the Radiolaria with fauna described in Deep Sea Drilling In summary, despite the great lithological diversity, we believe Project reports (for example, Riedel and Sanfilippo, 1974) suggests that all the rocks of the Ayios Photios Group can be viewed in a Middle-Jurassic to Early Cretaceous age for the Episkopi terms of a passive continental margin, ranging in age from Late radiolarites. Triassic to at least Early Cretaceous. Manganiferous Partings. The higher levels of the most thinly bedded sequences with abundant radiolarites, but without coarse DHIARIZOS GROUP: terrigenous clastics, are characterized by occasional partings of CONTINENTAL MARGIN VOLCANISM black manganiferous siltstones as much as 0.15 m thick (Fig. 3, B, section 22). Similar manganiferous partings have been noted in sed- Phasoula Lavas iments associated with the Phasoula lavas of the Dhiarizos Group (see below). Petrographical analysis shows that these partings are Substantial developments of mostly pillowed basaltic lavas, essentially manganese-rich turbiditic siltstones in which the man- termed the Phasoula lavas (Fig. 1), crop out in a broad arcuate belt ganese has apparently migrated into the relatively porous siltstones in the southwest part of the area (Fig. 2). In this belt the lavas are during diagenesis. structurally juxtaposed with major sheets of serpentinite and metamorphic rocks (Woodcock and Robertson, 1977). As the pe- Interpretation of the Episkopi Formation trography of the Phasoula lavas ("Mamonia Lavas") has already been discussed in detail by Lapierre (Lapierre, 1975; Lapierre and Although a complete facies analysis of the Episkopi Formation Rocci, 1976), we concentrate here on the field relations of the ex- would require more information about the pre-emplacernent trusive rocks and their associated sediments. tectonic setting (see below), a number of points can be made at this Because the base of the pillow lava pile is not seen, the total juncture. The lower terrigenous facies is taken to represent an up- thickness of the lavas is indeterminate, but it must exceed several ward continuation of the relatively proximal flysch that dominates hundred metres. Within the lavas there are intercalations of pelagic the underlying Vlambouros Formation. Likewise, the various limestones and occasional radiolarites which, together with com- thin-bedded and more fine-grained siltstone laminites and siltstone parable sediments immediately overlying the lavas (see below), are partings noted in many other sections are interpreted as more distal collectively termed the Kholetria Member (Swarbrick and turbidites derived from the same source areas. Robertson, unpub.; Fig. 1). Field relations demonstrate that the in- By comparison, the limestone conglomerates are viewed as a se- tralava sediments (Fig. 3, A, section 9) were deposited during ries of major submarine slides resulting from the disintegration of breaks in volcanism, rather than all having been tectonically inter- the outer edge of a carbonate platform located outside Cyprus. The calated later, as maintained by Lapierre (1975). Locally, the highest amalgamation of several conglomeratic or calcareous units to form levels of the lava sequence are overlain by thinly bedded pink and a single major redeposited horizon probably represents repeated gray calcilutites, which then pass up into gray and black calcilutites influxes of coarse calcareous material during a related major sliding possessing numerous manganiferous encrustations and partings event. The various finer grained calcarenites and calcilutites are (Fig. 3, A, section 8). Petrographically, the calcilutites exhibit likely to be more distal calciturbidites generated by the same sliding abundant Halobia filaments in a matrix of micritic limestone partly episodes. recrystallized to microspar. There are also numerous early The finely laminated radiolarian mudstones are interpreted as diagenetic calcite concretions, less than 0.01 m in diameter, which relatively deep-water hemipelagic sediments. Of these the green and impart a lumpy texture, akin to typical Ammonitico Rosso (Ber- gray mudstones, often associated with coarser grained sandstones, noulli and Jenkyns, 1974; Jenkyns, 1974). are regarded as being proximal deposits relative to the red, more Although local field relations are obscure, it is likely that the cal- oxidized, and stratigraphically condensed radiolarian mudstones. cilutites pass up into several hundred metres of finely laminated red Likewise, the radiolarites, which predominate in the upper levels of and reddish-purple radiolarian siltstones and radiolarites with thin sequences free of coarse terrigenous sediments, are interpreted as partings of silt turbidites, calcilutites, and manganiferous siltstones among the most distal deposits of the Episkopi Formation. Strong (Fig. 3, A, section 7). Comparable sediments have been noted in

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general spatial association with the Phasoula lavas, especially in the Although not now exposed in Cyprus, substantial assemblages of Akamas Peninsula and the Ayia Varvara area (Fig. 2). Similar autochthonous Mesozoic carbonate platform rocks are known hemipelagic radiolarian sediments have also been found above from the Antalya area of southwest Turkey (Brunn and others, comparable Upper Triassic pillow lavas in the Antalya Complex of 1971; Woodcock and Robertson, 1979). The planktonic southwest Turkey (Woodcock and Robertson, 1979). Critically, foraminiferal micrites seen within some of the Petra tou Romiou the Dhiarizos hemipelagic sediments are closely comparable with blocks are not found in the Ayios Photios Group rocks but may the highest stratigraphical levels of the most distal sequences of the have been deposited outside Cyprus in relatively shallow water ad- Ayios Photios Group — for example, the Khapotami River sections jacent to the inferred carbonate platform from which Petra tou (Fig. 3, B, section 22). The significance of this important link be- Romiou blocks are thought to have been derived. tween the Ayios Photios and Dhiarizos Groups is discussed below. Interpretation of the Dhiarizos Group Loudra tis Aphroditis Breccias The extremely vesicular nature of the Loudra tis Aphroditis In sharp contrast to the uniformly pillowed Phasoula lavas, there breccias, coupled with the interstratification of both pillowed and are separate occurrences of a volumetrically subordinate but dis- nonpillowed flows, is taken as evidence of extrusion in shallow tinctive assemblage of highly vesicular lava breccias, volcaniclastic water, possibly in part subaerially. Furthermore, the intercalations siltstones, and tuffs that crop out particularly in the coastal areas, of primary autobreccias and sedimentary volcanic breccias points Loudra tis Aphroditis and Petra tou Romiou, and also in the to spasmodic lava eruption on a highly unstable and relatively Akamas Peninsula (Fig. 2). The extrusive rocks, which are both pil- steeply sloping sea floor. Although comparable features are to be lowed and nonpillowed, range from basalts to trachytes and ande- expected in a variety of tectonic settings, including oceanic islands, sites (Lapierre, 1975). Chemically, these rocks represent a strongly oceanic fracture zones, and close to active ocean ridges, in Cyprus fractionated suite of high-titanium sodic lavas (Lapierre and Rocci, the spatial association of the Loudra tis Aphroditis breccias with 1976). Although the original extrusive relationships of the Loudra the shallow-water Petra tou Romiou limestone and the Ayios tis Aphroditis breccias are uncertain because of extreme tectonic Photios sediments in general, points to eruption in a continental disruption, these rocks show a marked spatial association with margin setting. Evidence from the Antalya Complex of southwest large blocks of reef and pelagic limestone discussed below. Turkey strongly supports this contention (Woodcock and Robertson, 1979). The generally pillowed, vesicular, and petrologi- Petra tou Romiou Formation: Exotic Blocks cally homogeneous character of the Phasoula lavas relative to the Loudra tis Aphroditis breccias is indicative of more quiescent erup- Blocks of white, generally crystalline limestone, first termed the tion on a sea floor of subdued topography. The various sedimen- Petra tou Romiou Limestone by Henson and others (1949), are tary intercalations of ferruginous calcilutites, radiolarites, and found scattered throughout the allochthonous terrains of the Ayios manganiferous deposits are interpreted as deep-water pelagic sedi- Photios Group, as well as in spatial association with the Loudra tis ments deposited slowly some distance above the Upper Triassic Aphroditis breccias. The blocks are generally subrounded, often calcite compensation depth. Unlike the Loudra tis Aphroditis brec- with markedly slickensided margins. They range in diameter from cias, the nature of the Phasoula lavas and their related sediments is several metres to more than 40 m, as in the case of the largest consistent with genesis in an open marine setting some distance known olistoliths located near Episkopi village (Fig. 2). In general, from the edge of the Mamonia continental margin. the largest blocks tend to be most numerous in the southeast of the District, whereas much smaller blocks are particularly STRUCTURE OF THE MAMONIA COMPLEX common close to the Troodos Massif (for example, Ayios Photios, Fig. 2). Our interpretation of the gross geometry of the Mamonia Com- Petrographically, the majority of the exotic blocks of Petra tou plex is shown schematically in Figure 4; regional variations, as yet Romiou Limestone are recrystallized shallow-water carbonate only poorly understood, are currently being investigated by R. E. facies in which ooids, pisolites, pellets, echinoid and coral frag- Swarbrick. ments, algae, benthonic foraminifera, and occasional agglutinating In general, the Ayios Photios Group overlies, with tectonic con- foraminifera can all be recognized in the less recrystallized samples. tact, the autochthonous Kannaviou Formation in the northeast and This material is closely comparable with the shallow-water car- mostly the Dhiarizos Group in the southwest of the area. The ex- bonate debris in both the Vlambouros and Episkopi Formations. In tent of allochthoneity of the Dhiarizos Group relative to the Ayios contrast, some of the generally smaller blocks are composed of pink Photios Group and the Troodos Complex is uncertain. An impor- or gray, often slightly recrystallized calcilutites containing occa- tant structural element in the southwest of the area is an arcuate sional ammonites of Late Triassic (Carnian-Norian) age (Henson belt of serpentinite bodies, associated with minor tectonic slivers of and others, 1949; Pantazis, 1967). In addition, some of the smaller metamorphic and Troodos ophiolitic rocks. The Ayios Photios, blocks in the Ayios Photios area include calcareous breccias with Kannaviou, and Troodos rocks are variously overlain by the occasional angular clasts of basalt and red shale, as much as 5 cm in Kathikas mélange, a postemplacement sedimentary unit (M. A. diameter. When viewed in thin section, all the derived clasts are Naylor and R. E. Swarbrick, unpub.), and then by the Maastrich- found to be set in a matrix of unrecrystallized micritic limestone tian and Tertiary chalks of the Lefkara Formation. containing planktonic foraminifera. Comparable provenance of the Petra tou Romiou limestone Structure Styles in the Ayios Photios Group blocks and the redeposited facies of both the Vlambouros and Episkopi Formations is consistent with the view that all these rocks Most of our structural data are from mesoscopic folds in the were derived from a contemporaneous carbonate platform. major southeastern outcrops of the Ayios Photios Group, with

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fewer data from the Akamas Peninsula. Fold style is dependent on tic of a single episode of "sheet" deformation — that is, deforma- lithology. The thinly bedded limestones, sandstones, siltstones, and tion dominated by planar simple shear (Hansen, 1971; Woodcock, cherts typically form angular single-hinged folds in association with 1976). The subhorizontal axis dispersion and mean axial plane angular box folds (Fig. 5, A, B). By contrast, the thicker bedded suggest that subhorizontal sheets are a major element in the struc- sandstones and limestones show more rounded styles (Fig. 5, C). ture of the Ayios Photios Group. If emplacement of these sheets Fold wavelengths are usually in the range 1 to 10 m, with interlimb was approximately perpendicular to the mean fold axis, it was angles varying from 45° to 90°. Although many folds apparently toward either about 026° or 206°. approach Ramsay's (1967) Class 2 (similar) type, they in fact com- The evidence for the sense of emplacement is shown in Figure 7. prise an alternation of Class 3 folds in the incompetent units and Arrows show fold facing and vergence (asymmetry) directions at Class 1C folds in the more competent units. individual sampled localities, bounded by a 95% confidence area Zones of local inversion and conflicting fold-vergence directions where possible. There is no consistent southwestward vergence of (see below) imply the existence of megascopic overturned or re- folds as implied by Lapierre (1975). Of those localities where ver- cumbent folds, but attempts to delineate these have so far proved gence could be determined, about 54% show vergence to the unsuccessful. This lack of continuity of major structures and southwest, 38% to the northeast, and 8% to the northwest. To be stratigraphy is highly characteristic of the deformation of the Ayios consistent with Lapierre's interpretation, all the northeast-verging Photios Group. The sediments exist as deformed sheets bounded by folds would have to represent the short limbs of large-scale tectonic contacts, within which the stratigraphical and structural southwest-verging folds. However, this possibility is strongly op- organization is more coherent. However, even within single sheets, posed by the fold facing directions (see Shackleton, 1958) deter- the more competent parts of the sequence are often disrupted to mined from cross-lamination and graded bedding. Whereas in form slabs and blocks isolated within less competent material. No Lapierre's scheme, all folds should face southwest, we have re- cleavage is developed even close to sheet margins. The sheet con- corded only about 17% facing in this direction. The majority, tacts, normally gradational rather than sharp, cannot be traced any 66%, instead face toward the northeast with a small remainder fac- distance in the field. Despite this, the sheets appear to be on the ing northwest. At three particularly informative localities, the folds order of 0.1 to 2 km wide and 200 m thick, closer to the estimates face northeast but verge to the southwest, implying the existence of of Ealey and Knox (1975) rather than to the size of the major major inverted zones, several of which can be traced some distance nappes postulated by Lapierre (1975). along strike on the basis oi: overturned bedding (Fig. 7). We inter- pret them as the inverted limbs of large northeast-facing recumbent Structure Attitudes in the Ayios Photios Group folds, now probably disrupted (Fig. 4). The areas showing southwest-facing folds, and many of those Measurements of fold axes and axial planes from the whole area showing southwest vergence but undetermined facing, are located (Fig. 6) show considerable dispersion, more than implied by either close to the Troodos Massif or to large sheets of Troodos Lapierre (1972, 1975) and Turner (1973). However, there is no rocks in the west of the area (Figs. 4, 7). This suggests that these evidence that this dispersion is due to polyphase deformation. atypical folds may owe their origin to the tectonic juxtaposition of Lapierre (1972, 1975) postulated an early fold phase trending the Troodos Complex with the Mamonia Complex (see below) about 120°, followed by a later one at about 060°. The mean axis in rather than to the initial emplacement of the Mamonia rocks. Figure 6, A, at 03/116 is consistent with Lapierre's early phase, but the dispersion of axes is in a horizontal plane rather than about a Serpentinite Belt trend of 060°. Refolded folds are very rarely seen and where present show no consistent refolding geometry from outcrop to outcrop. The structure of the Mamonia Complex is complicated by We regard these cases as local heterogeneities in a single relatively tectonically introduced masses of serpentinite, Troodos and simple kinematic picture. The planar dispersion of fold axes, Dhiarizos igneous rocks, and metamorphic rocks that crop out in coupled with the dispersion of axial plane poles about an axis 01/ an arcuate belt in the southwest of the Mamonia Complex (Figs. 2, 118, which statistically parallels the mean fold axis, is characteris- 7). Particularly on the concave northeastern margin of this belt,

S TRA TIGRA PHIC CONTACT

A.PC. \ % Dhiarizos Group

Figure 4. Semidiagrammatic northeast-southwest section across southwest Cyprus, showing major tectono-stratigraphic units and their relationships.

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serpentinite fabrics and igneous slivers dip steeply northeastward sheets. A similar situation has already been inferred for a separate or are subvertical. This contrasts strongly with the subhorizontal mass of melange, the Moni melange, located in southern Cyprus attitude of the sheets in the adjacent Ayios Photios sediments (Fig. (Robertson, 1977b). 4). This strongly discordant relationship makes it unlikely that the serpentinite sheets were entrained along the base of the Mamonia INTERPRETATION OF THE MAMONIA ALLOCHTHON allochthon during emplacement over a Troodos basement, as pro- posed by Lapierre (1975). Moreover, in several outcrops (for Extent of the Allochthonous Rocks example, Marathounda, Fig. 2), the Troodos pillow lavas as- sociated with the serpentinites pass stratigraphically upward into In agreement with Kluyver (1969), Lapierre (1972, 1975), and metalliferous umbers (Robertson, 1975) and then into the volcani- Ealey and Knox (1975), the Ayios Photios rocks must be clastic sequence of the Kannaviou Formation (Robertson, 1977c). allochthonous relative to the Troodos Complex wherever they This is strong evidence that most of the serpentinites and associated overlie the autochthonous Campanian and Maastrichtian Kan- igneous rocks represent upthrust parts of local Troodos basement, naviou Formation (Fig. 4). Since the allochthon is generally over- rather than substantially allochthonous bodies emplaced with the lain by late Maastrichtian chalks of the Lefkara Formation (Man- other Mamonia rocks. tis, 1970), the emplacement of at least this part of the allochthon Consequently, although we agree with Lapierre (1975) that the must have taken place wholly within the Maastrichtian, a period present attitude of the major serpentinized sheets in the Mamonia not exceeding 4 m.y. The evidence of gross allochthoneity of the Complex imparts a northeast-dipping grain to the Mamonia struc- Ayios Photios rocks is less clear where they overlie Dhiarizos rocks ture, we believe that their emplacement was later than, and in the (Fig. 4). However, some degree of mutual allochthoneity is indi- opposite sense to, that of the Ayios Photios Group sedimentary cated by the strikingly different sedimentary features of the two groups, particularly the much more distal nature of the Dhiarizos, relative to the Ayios Photios rocks. In contrast, as the base of the Dhiarizos Group is never exposed in southwest Cyprus, the rela- tionship to the adjacent Troodos and Kannaviou rocks cannot be definitely established. For the present discussion we regard the Dhiarizos Group as the local autochthon to a wholly allochthonous unit comprising the Ayios Photios sedimentary rocks.

Mechanism of Emplacement

A priori, two main possible modes of emplacement can be con- sidered. The first mechanism would involve tectonic accretion at the base of an active trench slope, giving rise to a subduction com- plex (Karig and Sharman, 1975). If this were the case, the gross structural geometry (Fig. 4) and the dominant fold-facing direction would then suggest subduction of Troodos ocean crust from the present northeast beneath a continental margin to the southwest. Alternatively, the second mechanism would involve unconstrained gravity sliding of rocks down a continental margin. In this case, fac- ing directions would imply a controlling slope dipping to the pres- Figure 5. Typical fold styles in Ayios Photios Group sediments. ent northeast. Bedding is defined by arbitrary markers; dip isogons are shown at Some features of the Ayios Photios rocks are consistent with both 30° intervals. A: Thin-bedded siltstones and shales, southwest of emplacement mechanisms. For instance, the nonmetamorphic state Episkopi. B: Shales with thin siltstones, Khapotami River. C: Thick of most of the sediments and the markedly different mechanical re- sandstone interbedded with shales, Khapotami River. sponses of differing sediment types both point to high-level defor-

— • Figure 6. Lower-hemisphere equal-area plots of fold axes (A) and fold axial plane poles (B) in Ayios Photios Group. Large solid circle marks mean axis or pole; open circle marks pole to dom- inant girdle of axes or poles, each surrounded by 95% confidence area.

n = 163 n=136

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mation; varying consolidation states in generally poorly lithified In contrast, the features of the Mamonia allochthon are readily sediments would then exert the major control on deformation explained by a gravity-sliding emplacement mechanism. Indeed, styles. The low-angle structural repetition could also be explained there is a tendency for the more proximal facies to crop out farther by both the mechanisms. northeast than the more distal facies of the Ayios Photios Group. Other factors are hard to reconcile with a subduction complex. For instance, the proximal Ayios Photios sequence (Fig. 3, A, sec- First, the allochthon is much thinner than any known ancient or tion 19) now occurs close to the Troodos Massif, whereas the distal recent subduction complex, perhaps well under 500 m. Second, on Khapotami River sequence: (Fig. 3, A, section 22) crops out in the structural grounds, there is a complete absence of the organized se- extreme southwest of the complex. A similar tendency has been quential repetition characteristic of accretionary wedges; instead, noted in the Moni mélange of southern Cyprus (Robertson, 1977b) the Dhiarizos rocks form a relatively undeformed basement to a and may reflect the greater potential energy, and therefore longer substantial part of the Ayios Photios rocks. Also, the combination transport distance, of slides from the proximal, upper parts of the of extreme disruption of the sedimentary sheets with a complete margin. absence of pervasive tectonic fabric is difficult to reconcile with a In summary, we believe that the main emplacement of the Ayios constrained trench-accretion model. Where comparable sediments Photios Group sedimentary sheets was by gravity sliding of sedi- have been deformed in a probable accreting wedge in the Pindos ments down a continental margin slope dipping to the present zone, Greece (Smith, 1976), they now form an organized stack of northeast. Recent gravity slides down continental margins are well thrust sheets, each of which can be traced several tens of kilometres known (Jacobi, 1976; Moore and others, 1976), and the volume of along strike (Smith and Moores, 1974). Third, on stratigraphical the Ayios Photios sediments of southwest Cyprus (between 1011 grounds, there is a total absence of the age and facies polarity and 1012 m3) is well within the range of volumes of individual re- characteristic of well-documented accretionary prisms. Indeed, cent slumps, which exceed 1012 m3 in several cases (see, for exam- rocks of all ages, including the coarsest most proximal Vlambouros ple, Heezen and Drake, 1964). A similar mechanism of gravity flysch, are found as small disrupted sheets throughout the emplacement has been inferred for the volumetrically smaller, but Mamonia Complex. related, Moni mélange of southern Cyprus, in which olistoliths of

Figure 7. Map of southwest Cyprus, showing fold vergence and facing direc- tions, structurally inverted zones, and out- crops of serpentinites and metamorphic rocks.

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almost all the Mamonia rocks are found floating in a matrix of turbidity currents into the deep pelagic environment — for exam- hemipelagic clays (Robertson, 1977b). ple, as recorded by the distal turbidites overlying the Phasoula lavas. Superimposed on this general subsidence trend, the Akamas DISCUSSION AND CONCLUSIONS: sandstones represent a major renewed influx of quartzose material NORTHERN MARGIN OF THE TROODOS OCEAN into the area in Early Cretaceous time (Fig. 8). This material was apparently generated by prolonged reworking on a shallow A most important factor is the paleomagnetic evidence (Moores current-swept continental shelf, but probably then redeposited into and Vine, 1971; Lauer and Barry, 1976) that since Late Cretaceous a deeper water hemipelagic environment. Significantly, the Early time the Troodos Massif, and presumably the Mamonia Complex Cretaceous was a time of major tectonic activity in the Greek re- also, have been rotated anticlockwise by as much as 90°. The postu- gion, with ophiolite emplacement, metamorphism, and volcanicity lated Mesozoic continental margin therefore lay northwest of the (Hynes and others, 1972). This activity may have had repercussions Maastrichtian position of southwest Cyprus and sloped southeast- farther east. ward toward it (Robertson, 1977b). This interpretation raises the The presence of a passive continental margin located to the orig- problem of the location of possible autochthonous remnants of the inal northwest of Cyprus throughout Jurassic and into Cretaceous Mamonia margin; the probable large translations accompanying time implies the existence of some form of adjacent contemporane- the Tertiary rotation of Cyprus give considerable choice. Parrot ous oceanic area to the southeast. We take the Dhiarizos igneous (1973) hypothesized that Cyprus was against the Levant coastline, rocks to represent a marginal strip of this ocean and the Troodos joining Troodos with the Hatay (southeast Turkey) and Baer-Bassit Complex to be a remnant of the much younger Late Cretaceous (Syria) ophiolites, but we are impressed by the close similarity of part of the same ocean. However, an important question is whether the Mamonia Complex with the Antalya Complex of southwest or not spreading was continuous through Jurassic and Early Creta- Turkey (Marcoux, 1967; Delaune-Mayere and others, 1976; ceous time. The sedimentary evidence of steady subsidence on the Woodcock and Robertson, 1979); we regard the carbonate plat- Mamonia margin through the Jurassic is consistent with continued form massifs and associated rocks of the Lycian Taurus (Brunn and spreading. others, 1971) as the most likely relatively autochthonous remnants On the other hand, there is no evidence in Cyprus or in southern of the Mamonia margin. Turkey of the accretionary prism expected if a substantial tract of We consider that the Mamonia Complex records an early Mesozoic oceanic crust had been subducted. In Baer-Bassit (Syria), Mesozoic phase of crustal extension leading to the development of there is evidence of Early Cretaceous alkaline and peralkaline vol- a rifted continental margin. Our evidence suggests initial rifting of a continental area during or before Late Triassic time, reflected in the PRE-LATE TRIASSIC KEY deposition of the Vlambouros flysch (Fig. 8). This was deposited, 1 Carbonate platform |i i probably in a fault-bounded graben, along the whole length of the incipient margin represented in southwest Cyprus. The upward Continental crust transition to more oxidized sediments toward the top of the Vlam- Oceanic crust bouros Formation may then reflect the onset of more open marine Marginal lava breccias \\*S*f\ conditions later in the Triassic. The absence both of extrusive vol- canic material from the Vlambouros sediments and of quartzose Sediments |

sediments among the Dhiarizos igneous rocks imply that the onset Slump plane of volcanism postdated the deposition of the Vlambouros facies. LATE TRIASSIC Initial volcanism, in Late Triassic time, produced the Loudra tis Aphroditis breccias, a suite of highly fractionated basalts, Approx. scale trachytes, and andesites. With continued crustal extension, the more homogenous, evenly pillowed Phasoula lavas were extruded 0 10 20 KM along the whole length of the recorded margin (Fig. 8). These lavas ' '—|-0 may mark the start of an episode of steady-state ocean-floor spread- -2 ing. An open marine setting is further supported by the Halobia- LATE TRIASSIC - EARLY CRETACEOUS bearing and metal-enriched pelagic sediments both within and im- mediately overlying the Phasoula lavas. In contrast to higher levels in the sequence, the complete absence of any redeposited clastic or calcareous facies within these lavas is consistent with eruption on a topographically elevated area, possibly an incipient ocean ridge. Later, the Jurassic history of the Mamonia continental margin was one of general subsidence, recorded by the deposition of increas- ingly more distal hemipelagic and pelagic sediments beneath the LATE CRETACEOUS carbonate compensation depth (Fig. 8). The recorded margin de- velopment was apparently fairly uniform along strike, except of the Marona pelagic limestones, which were restricted to the area where terrigenous clastic input was minimal. Periodic episodes of minor tectonic instability in the area were marked by the disintegration of the outer edge of the carbonate platform located northwest of Cy- prus in Mesozoic time. The displaced carbonate material was transported oceanward by mass flow into proximal areas and by- margin.

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canism (Parrot, 1974, 1977) along part of a Mesozoic continental REFERENCES CITED margin comparable with the Mamonia Complex. Indeed, the Akamas sandstone could be attributed to instability of the Bellamy, C. V., and Jukes-Brown, A. J., 1905, The geology of Cyprus: Mamonia continental margin consequent upon renewed ocean- Plymouth, England, Brandon, 72 p. Bernoulli, D., and Jenkyns, H. C., 1974, Alpine, Mediterranean and central floor spreading; the manganiferous horizons in the upper levels of Atlantic margin facies in relation to the early evolution of the Tethyan the Ayios Photios sediments would then reflect hydrothermal ac- ocean, in Dott, H. R., Jr., and Shaver, H. R., eds., Modern and ancient tivity related to the onset of this volcanism (R. E. Swarbrick, un- géosynclinal sedimentation: Society of Economic Paleontologists and pub.). Mineralogists Special Publication 19, p. 129—160. Biju-Duval, B., Lapierre, H., and Letouzey, J., 1976, Is the Troodos Massif If, as seems a strong possibility, little Jurassic oceanic crust was (Cyprus) allochthonous?: Société Géologique de France Bulletin, v. 18, ever created in the area, then only minor amounts of subduction p. 1347-1356. would be necessary. That some subduction did indeed take place is" Bouma, A. H., 1962, Sedimentology of some flysch deposits: Amsterdam, indicated by Kidd and Cann's (1974) evidence of preferential Elsevier, 168 p. one-way chilling directions of the Troodos sheeted complex; the Brunn, J. H., Dumont, J. F., Grackiansky, P. C. de, and others, 1971, Out- line of the geology of the western Taurides, in Campbell, A. S., ed., last position of the Troodos ridge is now west of the present Geology and history of Turkey: Tripoli, Petroleum Exploration Soci- Troodos outcrop, implying that whatever the original width, the ety of Libya, p. 225-255. northern part of the Troodos ocean was apparently subducted be- Calvert, S. E., 1966, Accumulation of diatomaceous silica in the sediments neath the Mamonia margin (Robertson, 1977c). of the Gulf of California: Geological Society of America Bulletin, v. 77, p. 569-596. Regardless of the earlier history, by Late Cretaceous time Carter, R. M., 1975, A discussion and classification of subaqueous mass- ocean-floor spreading had come to an end, followed by gravity transport with particular reference to grain-flow, slurry-flow and emplacement of the Ayios Photios sheets by, originally, southeast- fluxoturbidites: Earth Science Reviews, v. 11, p. 145-177. ward sliding down the Mamonia continental margin. Although the Cleintuar, M. R., Knox, G. J., and Ealey, P. J., 1977, The geology of Cyprus triggering mechanism remains unclear, the onset of subduction is and its place in the East-Mediterranean framework: Geologie en Mijnbouw, v. 56, p. 66-82. one possibility, as proposed by Smith and Woodcock (1976a, Delaune-Mayere, M., Marcoux, J., Parrot, J. F., and others, 1976, Modèle 1976b) for analogous, but smaller, sheets in Othris, central Greece. d'évolution Mésozoïque de la paleo-marge Téthysienne au niveau des The Ayios Photios sheets originally came to rest on a basement nappes radiolaritiques et ophiolitiques du Taurus Lycien, d'Antalya et comprising both Dhiarizos marginal oceanic crust and already du Baër-Bassit, in Biju-Duval, B., and Montadert, L., eds., Interna- tional symposium on the structural history of the Mediterranean ba- tectonically juxtaposed Troodos oceanic crust and related sedimen- sins: Paris, Editions Technip, p. 79-94. tary cover. Some degree of tectonic interaction between the Ealey, P. J., and Knox, G. J., 1975, The pre-Tertiary rocks of S. W. Cyprus: Troodos and Dhiarizos "oceanic" rocks then resulted in the Geologie en Mijnbouw, v. 54, p. 85—100. tectonic intercalation of serpentinite and Troodos ophiolitic rocks Gass, I. G., 1960, The geology of the Akamas Peninsula: Cyprus Geological to form the arcuate belt through the southwest part of the Survey Department Report, 1959, p. 19-29. Hansen, E., 1971, Strain facies: New York-Heidelberg-Berlin, Springer- Mamonia Complex. Once mobilized, the serpentinite reached the Verlag, p. 207. sea floor in places, then gave rise to low-angle serpentinite flows, as Heezen, B. C., and Drake, C. L., 1976, Grand Banks slump: American As- extensively developed in the southwest part of the area (Khapotami sociation of Petroleum Geologists Bulletin, v. 48, p. 221-225. River, Mavrokolymbos, Fig. 2). Henson, F. R. C., Browne, R. V., and McGinty, J., 1949, A synopsis of the stratigraphy and geological history of Cyprus: Geological Society of By late Maastrichtian time, major tectonic activity had ceased in London Quarterly Journal, v. 105, p. 1—41. the area; parts of the Mamonia Complex were then rapidly rede- Hynes, A. J., Nisbet, E. G., Smith, A. G., and others, 1972, Spreading and posited to form the virtually undeformed Kathikas melange, and emplacement ages of some ophiolites in the Othris region (eastern cen- then the whole area was blanketed by pelagic chalks in late M!aas- tral Greece): Deutschen Geologischen Gesellschaft Zeitschrift, v. 123, p. 455-468. trichtian to early Tertiary time (Mantis, 1970; Robertson and Hud- Jacobi, R. D., 1976, Sediment slides on the northwestern continental mar- son, 1974). gin of Africa: Marine Geology, v. 22, p. 157 -176. Finally, with regard to previous regional interpretations, we find Jenkyns, H. C., 1974, Origin of red nodular limestone (Ammonitico Rosso, no significant evidence that the Mamonia Complex was emplaced Knollenkalke) in the Mediterranean Jurassic: A diagenetic model, in from the present northeast over the Troodos Massif (Lapierre, Hsii, K. J., and Jenkyns, H. C., eds., Pelagic sediments: On land and under the sea: International Association of Sedimentologists Special 1975), nor signs that any major part of the Troodos Complex was Publication 1, p. 249-277. ever thrust over the Mamonia Complex as a vast allochthonous Karig, D. E., and Sharman, G. F., 1975, Subduction and accretion at slab (Biju-Duval and others, 1976). Instead, all our evidence is trenches: Geological Society of America Bulletin, v. 86, p. 377-389. compatible with an "external" — that is, relatively local — tectonic Kidd, R.G.W., and Cann, J. R., 1974, Chilling statistics indicate an ocean- floor spreading origin for the Troodos Complex, Cyprus: Earth and origin for both the Troodos and Mamonia complexes (Robertson Planetary Science Letters, v. 24, p. 151-155. and Woodcock, 1979), rather than the distant "internal" origin fa- Kluyver, H. M., 1969, Report on regional geological mapping in Paphos vored by Ricou and others (1974, 1975). District: Cyprus Geological Survey Department Bulletin, v. 4, p. 21- 36. Lapierre, H., 1968a, Découverte d'une série volcano-sédimentaire proba- ACKNOWLEDGMENTS blement d'âge Crétacé supérieure au S. W. de l'île de Chypre: Académie des Sciences Comptes Rendus, v. D266, p. 1817—1820. We thank the British Natural Environment Research Council, 1968b, Nouvelles observations sur la Série sédimentaire de Mamonia the Royal Society, and the University of Cambridge for funding our (Chypre): Académie des Sciences Comptes Rendus, v. D267, p. 32 — 35. research in Cyprus; H. Lapierre, M. A. Naylor, I. Price, and R. E. 1970, Découverte de plusieurs phases orogénétiques Mésozoiques au Swarbrick for discussions in the field; and J. E. Dixon and R. E. Sud de Chypre: Académie des Sciences Comptes Rendus, v. D270, Swarbrick for comments on the manuscript. p. 1876-1878.

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1972, Les formations sédimentaires et éruptives des nappes de radiolaritiques et métamorphiques: Société Géologique de France Bul- Mamonia et leurs rélations avec le Massif de Troodos (Chypre) [Doc- letin, v. 17, p. 1024-1044. toral thesis]: Nancy, France, University of Nancy, 420 p. Riedel, W. R., and Sanfilippo, A., 1974, Radiolaria from the south Indian 1975, Les formations sédimentaires et éruptives des nappes de Ocean, in Davies, T. A., Luyendyk, B. P., and others, Initial reports of Mamonia et leurs rélations avec le Massif de Troodos: Société the Deep Sea Drilling Project, Vol. 26: Washington, D.C., U.S. Gov- Géologique de France Mémoires, v. 123, 132 p. ernment Printing Office, p. 771-815. Lapierre, H., and Rocci, G., 1976, Le volcanism alkalin du sud-ouest de Robertson, A.H.F., 1975, Cyprus umbers: Basalt-sediment relations on a Chypre et le problème de l'ouverture des régions Tethysiennes au Mesozoic ocean ridge: Geological Society of London Journal, v. 131, Trias: Tectonophysics, v. 30, p. 299-313. p. 511-531. Lauer, J. P., and Barry, P., 1976, Etude paléomagnétique des ophiolites de 1977a, The origins and diagenesis of cherts from Cyprus: Sedimentol- Chypre: Sciences de la Terre Réunion Annuaire, v. 4, 255 p. ogy, v. 24, p. 11-30. Mantis, M., 1970, Upper Cretaceous-Tertiary foraminiferal zones in Cy- 1977b, The Moni mélange, Cyprus: An olistostrome formed at a de- prus: Epithris, v. 3, p. 227—241. structive plate margin: Geological Society of London Journal, v. 133, Marcoux, J., 1976, Les séries des nappes à radiolaritiques et ophiolites p. 447-466. d'Antalya (Turquie): Homologies et signification probable: Société 1977c, The Kannaviou Formation, Cyprus: Volcaniclastic sedimenta- Géologique de France Bulletin, v. 18, p. 315-316. tion from a probable late Cretaceous island arc: Geological Society of Middleton, G. V., and Hampton, M A., 1973, Sediment gravity flows: London Journal, v. 134, p. 269-292. Mechanics of flow and deposition, in Middleton, G. V., and Bouma, Robertson, A.H.F., and Hudson, J. D., 1974, Pelagic sediments in the Cre- A. H., co-chairmen, Turbidites and deep-water sedimentation: Society taceous and Tertiary history of Cyprus, in Hsii, K. J., and Jenkyns, of Economic Paleontologists and Mineralogists Short Course, H. C., eds., Pelagic sediments: On land and under the sea: Interna- Anaheim, p. 1—38. tional Association of Sedimentologists Special Publication 1, p. 403 — Miyashiro, A., 1973, The Troodos ophiolitic complex was probably formed 436. in an island arc: Earth and Planetary Science Letters, v. 19, p. 218 — Robertson, A.H.F., and Woodcock, N. H., 1979, Evidence for the 224. emplacement of Mesozoic allochthonous rocks in southern Cyprus, in 1975, Origin of the Troodos and other ophiolites: A reply to Hynes: Proceedings, Colloquium on Geology of the Aegean region, 6th, Izmir, Earth and Planetary Science Letters, v. 25, p. 217-222. Turkey, 1977: Ankara (in press). Moore, D. G., Curray, J. R., and Emmel, F. J., 1976, Large submarine slide Shackleton, R. M., 1958, Downward facing structures of the Highland (olistostrome) associated with the Sunda Arc subduction zone, NE Border: Geological Society of London Quarterly Journal, v. 113, Indian Ocean: Marine Geology, v. 21, p. 211—226. p. 361-392. Moores, E. M. and Vine, F. J., 1971, The Troodos Massif, Cyprus and Smewing, J. D., Simonian, K. O., and Gass, I. G., 1975, Metabasalts from other ophiolites as oceanic crust: Evaluation and implications: Royal the Troodos Massif, Cyprus: Genetic implication deduced from pet- Society Philosophical Transactions, v. A268, p. 433—466. rology and trace element composition: Contributions to Mineralogy Mutti, E., and Ricci Lucchi, R., 1975, Turbidite facies and facies associa- and Petrology, v. 51, p. 49-64. tions from selected formations of the Northern Apennines: Interna- Smith, A. G., 1976, Plate tectonics and orogeny: A review: Tectonophysics, tional Congress of Sedimentologists, 9th, Nice, 1975, Field Trip A 11, v. 33, p. 215-285. p. 21-36. Smith, A. G., and Moores, E. M., 1974, The Hellenides, in Spencer, A. M., Nisbet, E. G., and Price, I., 1974, Silicified turbidites: Bedded cherts as re- ed., Mesozoic-Cenozoic orogenic belts: Data for orogenic studies: deposited ocean-ridge derived sediments, in Hsii, K. J., and Jenkyns, Geological Society of London Special Publication 4, p. 159-185. H. C, eds., Pelagic sediments: On land and under the sea: Interna- Smith, A. G. and Woodcock, N.H., 1967a, The earliest Mesozoic structures tional Association of Sedimentologists Special Publication 1, p. 351- in the Othris region, eastern central Greece: Société Géologique de 366. France Bulletin, v. (7) 18, p. 245-251. Pantazis, Th. M., 1967, The geology and mineral resources of the 1976b, Emplacement model for some "Tethyan" ophiolites: Geology, Pharmakios-Kalavassos area: Cyprus Geological Survey Department v. 4, p. 653-656. Memoirs, v. 8, 120 p. Smith, A. G., Hynes, A. J., Menzies, M., and others, 1975, The stratigraphy Parrot, J. F., 1973, Pétrologie de la coupe du Djebel Moussa, massif of the Othris Mountains, eastern central Greece: A deformed basique-ultrabasique du Kizil Dag (Hatay, Turquie): Sciences de la Mesozoic continental margin sequence: Eclogae Geologicae Helvetiae, Terre, v. 18, p. 143-172. v. 68, p. 463-481. 1974, Le secteur de Tamimah (Tourkmânnli): Etude d'une séquence Turner, W. M., 1973, The Cyprian gravity nappe and the autochthonous volcano-sédimentaire de la région ophiolitique du Baër-Bassit (nord- basement of Cyprus, in de Jong, K. A., and Scholten, R., eds., Gravity ouest de la Syrie): Cahiers ORSTROM, Série Géologique, v. 6, and tectonics: New York, John Wiley & Sons, p. 287-301. p. 124-146. Woodcock, N. H., 1976, Structural style in slump sheets: Ludlow Series, 1977, Assemblage ophiolitique du Baër-Bassit et termes effusives du Powys, Wales: Geological Society of London Journal, v. 132, volcano-sédimentaire: ORSTROM Travaux et Documents, v. 72, p. 399-415. 334 p. Woodcock, N. H., and Robertson, A.H.F., 1977, Origins of some Pearce, J. A., 1975, Basait geochemistry used to investigate past tectonic ophiolite-related metamorphic rocks of the "Tethyan" belt: Geology, environments on Cyprus: Tectonophysics, v. 25, p. 41-69. v. 5, p. 373-376. Ramsay, J. G., 1967, Folding and fracturing of rocks: New York, 1979, Imbricate thrust belt tectonics as a guide to emplacement of the McGraw-Hill Book Co., 568 p. Antalya Complex, S.W. Turkey, in Proceedings, Colloquium on Geol- Ricou, L. E., Argyriadis, I., and Lefevre, R., 1974, Proposition d'une origine ogy of the Aegean region, 6th, Izmir, Turkey, 1977: Ankara (in press). interne pour les nappes d'Antalya et le massif d'Alanya (Taurides oc- cidentales, Turquie): Société Géologique de France Bulletin, v. 16, p. 107-111. MANUSCRIPT RECEIVED BY THE SOCIETY AUGUST 31, 1977 Ricou, L. E., Argyriadis, I., and Marcoux, J., 1975, L'axe calcaires du REVISED MANUSCRIPT RECEIVED FEBRUARY 21, 1978 Taurus, un alignment de fenêtres arabo-africaines sous des nappes MANUSCRIPT ACCEPTED MAY 15, 1978

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