Vol. 5, No. 11 November 1995 INSIDE • Science in National Parks, p. 216 • North-Central Section Meeting, GSA TODAY p. 225 A Publication of the Geological Society of America • Southeastern Section Meeting, p. 227

Evidence of Collisional Processes Associated with Ophiolite Obduction in the Eastern Mediterranean: Results from Ocean Drilling Program Leg 160 Scientific Participants of Leg 160: A. H. F. Robertson* and K.-C. Emeis (Co-Chief Scientists), C. Richter (Staff Scientist), M.-M. Blanc-Valleron, I. Bouloubassi, H.-J. Brumsack, A. Cramp, G. J. De Lange, E. Di Stefano, R. Flecker, E. Frankel, M. W. Howell, T. R. Janecek, M-J. Jurado-Rodriguez, A. E. S. Kemp, I. Koizumi, A. Kopf, C. O. Major, Y. Mart, D. F. C. Pribnow, A. Rabaute, A. P. Roberts, J. H. Rüllkotter, T. Sakamoto, S. Spezzaferri, T. S. Staerker, J. S. Stoner, B. M. Whiting, J. M. Woodside Figure 1. JOIDES Resolution at Marseilles, France, prior to departing on Leg 160.

ABSTRACT driving force was tectonic loading by longer active (e.g., the Upper Creta- sional settings on land to the east to Recent drilling in the eastern the Eurasian plate. In this area the ceous Oman ophiolite). However, the areas of incipient collision on the Mediterranean Sea south of Cyprus leading edge is represented by the Troodos is an example of an ophiolite Mediterranean Ridge in the west (Cita has revealed important insights into Troodos ophiolite. The breakup and that is undergoing active emplacement and Camerlenghi, l990). One such area fundamental tectonic processes asso- subsidence history of the Eratos- today, in an area that is easily accessi- of incipient collision includes the ciated with continental collision and thenes Seamount, as revealed by ble and geologically well known. Much Eratosthenes Seamount, south of ophiolite emplacement. A transect drilling during Leg 160, is clearly of the evidence for this emplacement is Cyprus. Previous geophysical studies of four sites was drilled across the linked with the emplacement of the recorded beneath the sea to the south (Woodside, l977, l991; Krasheninnikov Africa-Eurasia plate boundary. The Troodos ophiolite. This underwent of Cyprus, along the boundary between et al., l994) suggest that the Eratos- results show that the African plate, strong surface uplift during active the African and Eurasian plates. This thenes Seamount is a fragment of con- represented by the Eratosthenes tectonic emplacement, associated area was a target of drilling during Leg tinental (or transitional-type) crust that Seamount, underwent rapid with collision of the seamount with 160 in March and April l995 (Figs. 1 is undergoing subsidence and breakup subsidence and related faulting the Cyprus margin. and 2). in a zone of incipient collision between in Pliocene-Pleistocene time. The The eastern Mediterranean Sea the African and Eurasian plates (Robert- INTRODUCTION (Fig. 3) is a remnant of the Mesozoic son, l990; Kempler, l993; Limonov et Tethys ocean (Dercourt et al., l993). al., l994; Robertson et al., l994, l995). *Corresponding author—Alastair Robertson, Many ophiolites were emplaced Different areas record various stages of Department of Geology and Geophysics, Uni- long ago by processes that are no versity of Edinburgh, Edinburgh, EH9 3JW, UK. Tethys closure, ranging from fully colli- Obduction continued on p. 219

ABCD E

Figure 2. Core photographs illustrating stages in the tectonic-sedimentary evolution of the Eratosthenes Seamount and the adjacent Cyprus margin. A: Oncolites (algal balls) that accumulated on a shallow-water carbonate platform in Miocene time (Site 966, Core 17R, Section 1, 45–65 cm). B: Limestone (Miocene?) composed of various types of clasts, reflecting current reworking in a shal- low-water shelf setting (Site 966, Core 13R, Section 1, 1–21 cm). C: Debris flow composed of clasts of altered shallow-water limestone in a matrix of muddy nannofossil ooze of early Pliocene age (Site 966, Core 8H, Section 1, 1-23 cm). D: Clast-rich nannofossil ooze of Pliocene age showing slumping and color banding. The slumping is related to collapse of the Eratosthenes Seamount (Site 965, Core 3H, Section 3, 35–58 cm). E: Calcareous silty mud with detrital gypsum of Messinian(?) age, possibly deposited in a saline lake located at the foot of the Cyprus slope (Site 968, Core 25X, Section 2, 108–132 cm). Obduction continued from p. 213

This hypothesis could be tested by drilling a transect of relatively shallow holes (most <300 m) across the Africa- Eurasia plate boundary. One hole was Figure 3. Outline map of drilled on the northern part of the the Mediterranean showing seamount plateau (Site 966), one on the main tectonic features the upper northern slopes (Site 965), and the locations of the sites one on a small high at the base of the drilled during Leg 160. This article deals only with the northern slope of the seamount (Site transect of sites drilled 967), and one on the lower slope of the between Cyprus and the Cyprus margin to the north (Site 968; Eratosthenes Seamount Fig. 4, inset). (Sites 965, 966, 967, and In this article we summarize the 968). The line with teeth new information gained by drilling, marks the deformation front and we demonstrate how this can be between the African and used to test a model of collisional pro- Eurasian plates. cesses and ophiolite obduction that is of general importance. The details of the recovery at the individual sites are recorded elsewhere (Emeis, Robertson, Richter, et al., 1995).

SUMMARY OF DRILLING RESULTS the Eratosthenes Seamount gave way to erosion and/or local accumulation of The nature of the basement of the gypsum and ferruginous muds in small Eratosthenes Seamount is unknown, marginal lagoons and/or lakes, as but it might represent transitional crust recorded at Sites 965 and 967 (Fig. 5). of a rifted passive margin. The presence By contrast, a much thicker (~150 m) of mafic igneous intrusions at depth is succession of inferred Messinian age suggested by the existence of a strong was deposited at Site 968 on the lower magnetic anomaly beneath the Cyprus slope. This was probably seamount and adjacent seafloor areas deposited in a large lake or inland sea, (Woodside, l977, l991). The oldest well below eustatic sea level. The exis- sediments recovered during Leg 160 are tence of Messinian lakes was previously undated shallow-water carbonates that inferred in the western Mediterranean underlie Upper Cretaceous pelagic Tyrrhenian Sea (Kastens, Mascle, et al., carbonates at Site 967 (Fig. 4). In the l990). pre–Upper Cretaceous, the Eratosthenes Distinctive matrix-supported brec- Seamount formed part of a carbonate cias occur between underlying shallow- platform, as widely exposed around the water carbonates and overlying nanno- eastern Mediterranean (e.g., in south- fossil oozes of early Pliocene age at Site ern Turkey and the Levant). Overlying 966. They formed by mainly mass-flow pelagic carbonates, of Upper Creta- processes during the early Pliocene ceous and middle Eocene age at Site (pre–4.5 Ma). The source of many of 967 and of exclusively middle Eocene the clasts was a shallow-water lime- age at Site 966, indicate accumulation stone, similar to the underlying succes- in a quiet deep-water (bathyal) setting. sion. Pliocene accumulation took place The absence of gravity input (e.g., tur- in a relatively deep-marine setting bidites) within the Upper Cretaceous (more than several hundred meters), and middle Eocene pelagic sediments based on microfossils in the matrix. is consistent with deposition on a Erosion of the limestones that are submerged platform or promontory, redeposited as clasts in the lower isolated from terrigenous input. The Pliocene might have been subaerial, Figure 4. Summary of the successions drilled on the Eratosthenes Seamount and lower slope of Eratosthenes Seamount area was proba- subaqueous, or both, but there is little the Cyprus margin. Lower left: Simplified bathymetry of the transect area. bly then still located well to the south evidence of clast rounding via sedimen- of areas of Tethys that experienced tary transport. A tectonic fabric present ophiolite emplacement and active mar- within several clasts could suggest gin deformation in the latest Creta- derivation from a faulted rock (e.g., ceous (Campanian-Maastrichtian; an erosional fault scarp). The presence ¸Sengör and Yilmaz, l981). of nannofossil mud clasts also indicates Middle Eocene pelagic carbonate that deep-marine sediments were accumulation was followed by shallow- reworked in an unstable slope setting. water carbonate deposition. The car- The Pliocene-Pleistocene succes- bonates accumulated in a near-reef, sions at each site are composed of nan- platform setting and are dated as early nofossil oozes interbedded with cal- Miocene at Site 967, on the basis of careous muds, numerous sapropels, benthic foraminifera (I. Premoli-Silva, and minor volcanic ash. The Eratos- 1995, personal commun.). Water thenes Seamount sites (Sites 965, 966, depths must have decreased by more and 967) are now at water depths rang- than several hundred meters between ing from 700 to 2900 m. These differ- the middle Eocene and the Miocene, ences in water depth are the result of which implies that surface tectonic differential subsidence of the seamount uplift of the Eratosthenes Seamount area. Much of this subsidence took must have taken place, in addition to place relatively rapidly. The early the effects of any eustatic sea-level Pliocene sediments accumulated in change. This uplift is not likely to have deep water, without evidence of a grad- been collision-induced, because the ual upward transition from shallow- subsequent Miocene shallow-water water conditions. Benthic foraminifers deposition took place under relatively indicate a further deepening after the tectonically stable conditions, but it late Pliocene, at least at Site 967. could instead reflect tectonic move- ments related to an earlier history of TECTONIC MODEL OF subduction. Regional and local evi- COLLISION AND dence (e.g., in Cyprus and Crete) sug- OPHIOLITE EMPLACEMENT gests that the present-day Africa-Eura- The new information obtained by sia plate boundary was already in drilling can be used to test and substan- existence in the eastern Mediterranean tiate a model of incipient collision and by the Miocene (Dewey and ¸Sengör, Figure 5. Logs summarizing only (from south to north) the mainly Messinian and lower ophiolite emplacement. The tectonic l979; Sengör¸ et al., l985; Robertson et Pliocene intervals of successions recovered during Leg 160. Southwest Cyprus is added for com- model to be tested maintains that, fol- al., l991; Meulenkamp et al., l994). parison (Orszag-Sperber and Elion, l989). Rapid subsidence of the Eratosthenes Seamount took lowing a more than 85 m.y. evolution During the Messinian salinity cri- place during the early Pliocene, associated with mass wasting and fault activity (Sites 966, 965, sis, shallow-water marine deposition on 967). Site 968 on the lower Cyprus slope and onshore Cyprus, however, documents a contrast- Obduction continued on p. 220 ing sedimentary and tectonic history (see text).

GSA TODAY, November 1995 219 Obduction continued from p. 219

as part of the passive margin of Gond- wana, the Eratosthenes Seamount is being thrust beneath the Troodos ophi- olite to the north. Related to this colli- sion there is a transition from exten- sional tectonics and collapse of the Eratosthenes Seamount in the south, to shortening in the north, beginning near the lower northern slope of the Eratosthenes Seamount (Fig. 6; Limonov et al., l994; Robertson et al., l994, l995). The new information gained during Leg 160 largely substan- Figure 6. Tectonic model of collision and ophiolite emplacement prior to Leg 160 drilling (Limonov et al., l994; Robertson et al., l994, l995). The tiates this model (Fig. 7). Eratosthenes Seamount is being thrust beneath the Troodos ophiolite to the north. The seamount plateau area is undergoing load-induced exten- sional faulting. There is a transition from extensional tectonics in the south to shortening in the north. This model was tested and substantiated Evidence of Load-induced during Leg 160. In addition, the interpretation of the seismic profiles suggests that the Eratosthenes Seamount is also being thrust beneath the Subsidence Levantine platform to the south, an aspect that was not investigated during Leg 160. The Eratosthenes Seamount is inferred to have collided with the active margin of the Eurasian plate to the north, including Cyprus, resulting in subsidence and collapse of the Figure 7. Plate tectonic seamount. An exponential increase in model of the evolution subsidence rate with time would be of the Eratosthenes predicted theoretically, as in the case of Seamount in relation to foredeeps associated with thrust and Cyprus. A: The Troodos nappe emplacement in mountain belts ophiolite formed possibly (e.g., Beaumont, l981; Stockmal et al., above an earlier north- dipping subduction zone. l986; Whiting and Thomas, l994). The The Eratosthenes Sea- paleontological evidence indicates that mount is shown as a rifted rapid subsidence of the Eratosthenes marginal continental occurred in the early Pliocene, and it fragment of the North may have begun earlier (Fig. 8). In African plate. B: The north- addition, the early Pliocene matrix-sup- ern plate was strongly ported breccias at Site 966 are indica- deformed in middle to tive of masswasting and accumulation late Eocene time, while on relatively steep submarine slopes. Eratosthenes was unaffected. C: Northward subduction in the Miocene Evidence of was reflected in supra– Related Faulting subduction zone extension Interpretation of seismic data sug- in Cyprus. Eratosthenes was gests that the northernmost part of the uplifted and overlain by shallow-water carbonates. Eratosthenes Seamount is now thrust D: Eratosthenes was emer- beneath Cyprus, including the overrid- gent during the Messinian ing Troodos ophiolite (Limonov et al., salinity crisis, and initial l994; Robertson et al., l994, l995). The collision with Cyprus seamount thus forms the footwall of an possibly began. E: The overriding thrust load. To what extent Eratosthenes Seamount did the footwall deform by faulting was thrust beneath the during load-induced collapse? This is a Troodos ophiolite, trig- current question for many on-land gering surface uplift and foredeep settings (e.g., Alps and relative southward dis- placement, accompanied Himalayas). If the effects of thrustload- by serpentinite diapirism. ing exceeded the flexural rigidity of the crust, then normal faulting would be anticipated. The incoming Eratos- thenes slab represents old (Mesozoic or older) crust that would be expected to behave in a relatively rigid manner, on theoretical grounds (Stockmal et al., l986). Nevertheless, flexurally induced faulting can be facilitated by preexist- ing zones of structural weakness in crust of any age. Seismic evidence indicates that the Figure 8. Inferred plateau area of the Eratosthenes tectonic history of the Seamount is currently tectonically northern margin of the active. A set of roughly east-west-ori- Eratosthenes Seamount. A: A stable bathyal ented fault zones, up to several hun- carbonate-depositing dred meters wide, cuts the uppermost setting. B: Flexurally Pliocene-Pleistocene sedimentary induced faulting related strata. Some of these faults exist as to onset of collision and large open cracks on the seafloor. Sev- the start of southward eral of the faults on the Eratosthenes ophiolite emplacement, Seamount plateau predate accumula- probably during the tion of the Pliocene-Pleistocene deep- Messinian salinity crisis. sea sequence. These faults are inter- C: Subsidence continued preted to represent the result of following the end of the flexurally induced faulting (Limonov et Messinian salinity crisis. D: The northern extension al., l994; Robertson et al., l994, l995). of the Eratosthenes Sea- Seismic data also suggest that a small mount collapsed as a ridge at the base of the lower northern result of flexural loading slope of the Eratosthenes Seamount is by the overriding Troodos underlain by a northward-dipping fault ophiolite, with a switch to zone (a reverse fault or thrust; Fig. 6). shortening in the north. Both this ridge and the adjacent lower slopes of the Eratosthenes Seamount appear to be undergoing tectonic short- ening. The ridge is apparently being detached from the downgoing Eratos-

Obduction continued on p. 221

220 GSA TODAY, November 1995 Obduction continued from p. 220 GSA International thenes Seamount and is being accreted GSA Foundation to the overriding thrust wedge. The Division Seeks Funds 3300 Penrose Place seismic evidence is interpreted to Pinar O. Yilmaz P.O. Box 9140 reflect a switch from flexurally induced President, International Division Boulder, CO 80301 (303) 447-2020 normal faulting in more distal (i.e., Although few in numbers, GSA southerly) areas of the footwall, to International Division members are shortening in areas closer to the over- an active group. The division is International Division riding thrust load (i.e., more northerly). cosponsoring Theme Session 2, Award Fund Drilling during Leg 160 provided Geology and Tectonics of the additional evidence in support of the Caribbean Region, at the GSA role of faulting in collision-related Annual Meeting in New Orleans. Enclosed is my contribution in deformation of the Eratosthenes The session is on Tuesday, Novem- the amount of $______Seamount, as follows: (1) Evidence of ber 7. We believe that this kind of for the International Division predominantly extensional faulting is international exchange of ideas Award Fund. Figure 9. Indication of relative sea-level present in the Upper Cretaceous and broadens our knowledge and gives middle Eocene sequences drilled at Site change through time. A: Site 967 on the PLEASE PRINT Eratosthenes Seamount. B: Southern Cyprus us new insight into geoscientific 967, and to a lesser extent in the mid- problems. Travel costs for speakers dle Eocene sequences recovered at Site (data from Robertson et al., l991). The timing Name ______and extent of relative sea-level change differs, from the Caribbean are funded by 966. For example, numerous small nor- reflecting locations on different plates until the International Division, the GSA Address ______mal faults are present within well- the Pliocene-Pleistocene, when the Eratos- Foundation, and Exxon Production cemented limestone. Unfortunately, thenes Seamount and the Troodos ophiolite Research Company. City/State/ZIP ______the timing of fault movement cannot began to collide. Because it is relatively new and Phone ______be determined. (2) Extensional faulting still small, the International Division was probably active in generating the has not yet reached a level of fund- highly immature matrix-supported ing that would give it access to matching funds from the GSA Foundation. There- breccias of early Pliocene age at Site (Gass and Masson-Smith, l963). Moores fore, the Division is requesting contributions, to supplement the dues paid by its 966. (3) At Site 965, Pliocene-Pleis- and Vine (l971) related the uplift of the members. These contributions will be used as part of the funding for symposiums tocene nannofossil muds and oozes Troodos ophiolite to the effects of at GSA annual meetings, to pay travel costs for non–North American speakers. All show evidence of widespread slumping diapiric protrusion of serpentinite. contributors will be listed in the symposium flyers. See the accompanying and reworking as debris flows that may Ultramafic rocks of the lower levels of coupon, or contact Pinar Yilmaz at (713) 423-7465, fax 713-423-7719. have been triggered by faulting. This the ophiolite sequence were hydrated Officers of the International Division are President Pinar Yilmaz, Exxon Explo- area today forms part of the steep and rose diapirically, uplifting the ration Company, Houston; Vice-President (and president-elect) James Skehan, upper slopes of the Eratosthenes ophiolite. It is now known that this Boston University; Second Vice-President Sandra Barr, Acadia University, Nova Seamount and is bounded by large nor- event took place in the context of colli- Scotia; and Secretary-Treasurer Frederick Simon, U.S. Geological Survey, Reston. mal faults; these faults may have had sional deformation within a large area an earlier history of movement that of the eastern Mediterranean (e.g., the was reflected in sediment instability. Kyrenia Range of northern Cyprus and (4) Fine-grained mud turbidites in the onshore southern Turkey ). In sum- 160: College Station, Texas, Ocean Drilling tional Association of Sedimentologists Special upper part of the sequence at Site 966 mary, documentation during Leg 160 Program (in press). Publication 12, p. 331–369. may reflect tectonically induced of the breakup and subsidence of the Gass, I. G., and Masson-Smith, D., 1963, The geol- Robertson, A. H. F., Kidd, R. B., Ivanov, M. K., redeposition from within the plateau Eratosthenes Seamount as a result of ogy and gravity anomalies of the Troodos Massif, Limonov, A. F., Woodside, J. M., Galindo-Zal- area. In addition, drilling at Site 967 Cyprus: Royal Society of London Philosophical divar, J., and Nieto, L., l994, Probing continental collision between the African and penetrated 700 m into the small com- Transactions, ser. A, v. 255, p. 417–467. collision in the Mediterranean Sea: Eos (Transac- Eurasian plates clearly links these tions, American Geophysical Union), v. 75, pression-induced basement ridge Kastens, K. A., Mascle, J., et al., l990, Proceedings events with emplacement and uplift of p. 233. mentioned above. The recovered sec- of the Ocean Drilling Program, Scientific results, the Troodos ophiolite. Volume 107: College Station, Texas, Ocean Robertson, A. H. F., Kidd, R. B., Ivanov, M. K., tion ends with a tectonic breccia that Drilling Program. Limonov, A. F., Woodside, J. M., Galindo- is mainly composed of limestone. Zaldivar, J., and Nieto, L., l995, Erastosthenes CONCLUSIONS Kempler, D., l993, Tectonic patterns in the eastern Geophysical logs (e.g., Formation Seamount, easternmost Mediterranean: Evidence Mediterranean. [Ph.D. thesis]: Jerusalem, Hebrew of active collapse and thrusting beneath Cyprus: MicroScanner) suggest that numerous Drilling during Leg 160 indicates University, 136 p. Terra Nova, v. 7, p. 254–264. zones of deformation and brecciation that one of the world’s most accessible Krasheninnikov, V. A., Udintsev, G. B., are present within the Upper Creta- and best documented ophiolites is in ¸Sengör, A. M. C., and Yilmaz, Y., l981, Tethyan Mouraviov, V. I., and Hall, J. K., l994, Geological evolution of Turkey: A plate tectonic approach: ceous and middle Eocene intervals at the process of active tectonic emplace- strucure of the Eratosthenes Seamount, in Tectonophysics, v. 75, p. 181–241. Site 967. At present, it seems likely that ment. This active emplacement is Krasheninnikov, V A., and Hall, J. K., eds., Geolog- ical structure of the northeastern Mediterranean ¸Sengör, A. M. C., Görür, N., and Sariöglü, F., 1985, Site 967 had a complex tectonic history accompanied by loading and collapse (Cruise 5 of the Research Vessel Akademik Nikolaj Strike-slip faulting and related basin formation in that may have involved, first, flexure- of the footwall, represented by the Strakhov: London, Historical Productions–Hall zones of tectonic escape: Turkey as a case study, related extensional faulting resulting Eratosthenes Seamount to the south of Ltd., p. 113–131. in Biddle, K. T., and Christie-Blick, N., eds., Strike- slip deformation, basin formation and sedimenta- from thrust loading of the Eratosthenes Cyprus. This collapse is accompanied Limonov, A. F., Woodside, J. M., and Ivanov, tion: Society of Economic Paleontologists and Seamount, and then large-scale com- by widespread extensional faulting that M. K., editors, l994, Mud volcanism in the Mineralogists Special Publication 37, p. 227–264. Mediterranean and Black Seas and shallow struc- pressional deformation and local sur- developed in response to crustal flexure ture of the Eratosthenes Seamount—Initial results Stockmal, G. S., Beaumont, C., and Boutilier, R., face uplift related to underthrusting ahead of the advancing thrust load. of the geological and geophysical investigations 1986, Geodynamic models of convergent margin beneath the overriding slab. The collapse and ophiolite obduction during the third “Training-through-Research” tectonics. Transition from a rifted margin to over- are taking place in a zone of incipient Cruise of the R/N Gelendzhik (June–July, l993): thrust belt and consequences for foreland basin UNESCO Reports in Marine Sciences, v. 64, 173 p. development: American Association of Petroleum Link with Ophiolite collision between the African and Geologists Bulletin, v. 70, p. 727–730. Emplacement Eurasian plates. The tectonic processes McCallum, J. E., and Robertson, A. H. F., 1990, Pulsed uplift of the Troodos Massif—Evidence Whiting, B. M., and Thomas, W. A., l994, Three- documented during Leg 160 may thus Load-induced collapse and under- from the Plio-Pleistocene Mesaoria basin, in Mal- dimensional controls on the subsidence of a help us to understand tectonic pro- pas, J., et al., eds., Ophiolites: Oceanic crustal ana- foreland basin associated with a thrust belt recess, thrusting of the Eratosthenes Seamount cesses associated with ophiolite obduc- logues: Nicosia, Cyprus, Geological Survey Depart- Black Warrior basin, Alabama and Mississippi: was generally synchronous with tion and the early stages of collision in ment, p. 217–230. Geology, v. 22, p. 727–730. emplacement of the Troodos ophiolite many other mountain belts. Meulenkamp, J. E., van der Zwaan, G. J., and Van Woodside, J. M., l977, Tectonic elements and (Fig. 9). The collapse and underthrust- Wamel, W. A., l994, On Late Miocene to Recent crust of the eastern Mediterranean Sea: Journal of ing of the footwall represented by the vertical movements in the Cretan segment of the Marine Geophysical Research, v. 3, p. 317–354. ACKNOWLEDGMENTS Hellenic arc: Tectonophysics, v. 234, p. 53–72. Eratosthenes Seamount took place from Woodside, J. M., l991, Disruption of the African early Pliocene (or late Miocene?) to We thank all who sailed with us Moores, E. M., and Vine, F. J., l971, The Troodos plate margin in the Eastern Mediterranean, in Pleistocene time, whereas the main during Leg 160, particularly the marine Massif and other ophiolites as oceanic crust: Salem, M. J., ed., The geology of Libya: New York, Evaluation and implications: Royal Society of Elsevier, p. 2319–2329. uplift of the Troodos ophiolite occurred technicians, for outstanding support. London Philosophical Transactions, ser. A, in the late Pliocene and Pleistocene v. 268, p. 443–466. Manuscript received May 6, 1995; revision received July 20, 1995; accepted July 25, 1995. ■ (McCallum and Robertson, l990; Poole REFERENCES CITED Orszag-Sperber, F., and Elion, P., l989, The sedi- and Robertson, l992). The two events Beaumont, C., l981, Foreland basins: Royal Astro- mentary expression of regional tectonic events are clearly inextricably linked. How- nomical Society Geophysical Journal, v. 65, p. during the Miocene-Pliocene transition in South- ever, in detail, strong surface uplift of 291–329. ern Cyprus: Geological Magazine, v. 126, p. 291–299. GSA’s the Troodos ophiolite appears to have Cita, M. B., and Camerlenghi, A., l990, The been delayed up to several million Mediterranean Ridge as an accretionary prism in Poole, A. J., and Robertson, A. H. F., 1992, Quater- nary uplift and sea-level change at an active plate Publications years after collapse of the Eratosthenes a collisional context: Geological Society of Italy, Memoirs, v. 45, p. 463–480. boundary, Cyprus: Geological Society of London Seamount began. This could reflect a Journal, v. 148, p. 909–921. Catalog time delay during which sufficient Dercourt, J., Ricou, L. F., and Vrielynck, B., editors, l993, Atlas of Tethys palaeoenvironmental Robertson, A. H. F., l990, Tectonic evolution of crustal thickening took place at depth maps: Paris, Gauthier-Villars, 307 p. Cyprus, in Malpas, J., et al., eds., Ophiolites and It’s to promote buoyant uplift of the over- oceanic lithosphere (Proceedings of the Interna- Dewey, J. F., and ¸Sengör, A. M. C., 1979, Aegean riding ophiolite. However, it seems tional Symposium, Troodos l987): Nicosia, and surrounding areas: Complex multiplate and Cyprus, Geological Survey Department, Free! unlikely that uplift of the Troodos continuum tectonics in a convergent zone: Geo- p. 235–252. ophiolite was driven by collisional pro- logical Society of America Bulletin, v. 90, p. 84–92. Robertson, A. H. F., Eaton, S., Follows, E. J., and cesses alone. Modeling of gravity data McCallum, J. E., 1991, The role of local tectonics 1-800-472-1988 has revealed that the Troodos ophiolite Emeis, K.-C., Robertson, A. H. F., Richter, C., and versus global sea-level change in the Neogene has a deep-rooted serpentinite core Leg 160 Scientific Party, 1995 Proceedings of the evolution of the Cyprus active margin: Interna- (303) 447-2020 Ocean Drilling Program, Initial reports, Volume

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