Plate Tectonics History of

NORMAN HERZ University of Georgia, Department of Geology, Athens, Georgia 30602 HARALAMBIE SAVU Institutul Geologic, 55 §os Kiseleff, Bucurest, Romania

ABSTRACT tures, and silicic volcanism, developed be- 1969). Study of geological and tectonic tween Moesia-Pannonia and the Tethys- processes showed that active plate bound- Similarities in lithology and age suggest Dinaric Oceans and between Pannonia and aries within the ocean basins and at most is- that the Moesian and Moldavian platforms the Siret Ocean. land arcs could be interpreted in terms of were united until late Precambrian tine In Paleocene time, a belt of calc-alkalic interaction between well-defined litho- when an independent geological evolution rocks (banatites) developed in western spheric slabs. However, observation of the began in parts of Romania and lasted Romania and the Balkan Mountains as a diffuse distribution of seismic activity and through Paleozoic time. In Middle Triassic result of plate convergence of Rhodope and the geologic complexity at conti- time, mafic rocks appeared in the East Car- Moesia as the last of Tethys was subducted. nent-continent plate boundaries has shown pathians and Dobrogea as part of a wide This was followed by a continental collision that care must be exercised when using the belt, caused by crustal distension, from the of Moesia and Pannonia and the uplift of hypothesis of plate tectonics to define cur- West Carpathians to the Caucasus. Plate the South Carpathians. volcanism rently or previously active plate boundaries separation led to the development of the and molasse developed as end stages of now situated within or between continental Siret Ocean between Pannonia and Mol- plate subduction and collision. Modern plates (McKenzie, 1969; Dewey and others, davia. earthquake activity of the Vrancea Moun- 1973). Jurassic sedimentation started as a tains and high heat flow in Transylvania Geophysical and geological data have shallow-water, transgressive facies except suggest that subduction is still going on been invoked to outline the shape and his- in spreading centers, such as the Siret around the great Carpathian arch. tory of the lithospheric plates caught be- Ocean and the proto-Apuseni area, which tween the Eurasian and African continental was then part of the Dinarides and whe::e INTRODUCTION masses (Dewey and others, 1973; Mc- ophiolites with interlayered chert and Recent advances in the earth sciences Kenzie, 1970; Smith, 1971; and others). radiolarite formed. By Early Cretaceous began with the application of the principles Investigators have postulated the present time, movement sense changed and the mi- of plate tectonics to define the boundaries existence of from two (McKenzie, 1970) to croplates were translated toward the stable of major lithospheric plates and to explain, eight or more (Dewey and others, 1973) craton. The Apuseni ophiolites were ob- at least qualitatively, the nature of the small lithospheric plates (microplates) be- ducted onto continental crust. Convergent processes occurring at their boundaries (Le tween Africa and Eurasia within the plate boundaries, with flysch, nappe struc- Pichon, 1968; Morgan, 1968; McKenzie, Mediterranean area. The study of the exis- tence and history of microplates that no longer behave as independent lithospheric fragments, but that are now welded to ad- jacent plates, is an even more difficult prob- lem. There is general agreement that the Tethyan seaway, which once existed be- tween and Africa, started to disap- pear with the opening of the Atlantic and with the beginnings of separation of North America from Europe (Smith, 1971). Movement to close the Tethyan seaway ap- parently acted upon a hinge set just west of Gibraltar. Relative movements of litho- spheric plates in different parts of the Mediterranean area were influenced by rel- ative movements caused by both (1) the dif- ferences in the longitudinal drift rates of European and African plates with respect to each other due to the nonuniform opening of the Atlantic, and (2) the subsequent northward drift of Africa relative to Europe acting on the Gibraltar hinge (Dewey and others, 1973). The timing of the start and the different phases of Atlantic rifting have Geological Society of America Bulletin, v. 85, p. 142SI-1440, 12 figs., September 1974

1429

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 W E

PANNONIAN

20 40 60km

Figure 2. Tectonic sketch map and cross sections of Romania. Map modified from Dumitrescu and Sandulescu (1970). Cross sections by H. Savu: A—A' between Vinga and Tibana, B—B' between Pilu and Bucharest. Legend: 1, sedimentary deposits (Paleozoic-Cenozoic): 2, Neogene volcanics: 3, ophiolites; a, stratified gabbro bodies: 4, pre-Alpine granites: 5, crystalline ¡¡chists (middle Precambrian-Paleozoic); a, granitic and (or) basaltic cover: 6, crystalline basement of the Moldavian and Moesian platform; a, granitic and (or) basaltic cover: 7, upper mantle: 8, faults: 9, overthrusts.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 PLATE TECTONICS HISTORY OF ROMANIA 1431

also been correlated to compressional fea- Deep fracture zones, such as the northern tures in the Mediterranean area. Transitory Anatolian fault, may represent former existence of microcontinents, sometimes transform faults along which extensive torn away from the major continents and strike-slip movement took place. Aligned other times collided with them and each zones of silicic or intermediate Neogene or other, further complicated the picture of Recent volcanism, accompanied by deep relative movements in the Mediterranean focus earthquakes, represent active zones of (Dewey and others, 1973). subducting oceanic plates; aseismic older In the Balkans and the eastern Mediter- volcanic belts associated with flysch de- ranean, widely accepted criteria for plate posits may represent former compressional regimes can be applied (Dewey and Bird, plate margins. In the eastern Mediterranean 1970). Ophiolites and radiolarian cherts and Balkan peninsula, microplates may ex- represent a remnant of oceanic crust and plain the widespread occurrences of these Figure 3. Index map, Romania 1:200,000 series. See mantle that originally developed by seafloor generally accepted criteria for past and con- description in text. Sections: no. 4, Vijeu (Bleahu and spreading and was later tectonically em- tinuing plate tectonics regimes (Smith, others, 1968a); no. 16, Arad (Papiu andGhenea, 1966); placed onto continental crust in a subduc- 1971; McKenzie, 1970; Dewey and others, no. 17, Brad (Bleahu and others, 1968b); no. 18, Turda tion zone. Compressional plate margins are 1973; Radulescu and Sandulescu, 1973; (Lupu and others, 1968); no. 20, Odorhei (Vasilescu and others, 1968); no. 25, Deva (Gherasi and others, represented by intense deformation — Bleahu and others, 1973). 1968); no. 28, Brajov (Patrulius and others, 1968); and especially as imbricate nappes, accom- Many reconstructions of Tethyan and no. 38, Tulcea (Miraufa and others, 1968). panied by silicic and intermediate vol- proto-Mediterranean paleogeography are canism — and regional metamorphism. based on reinterpretations of published de-

Figure 4. Ophiolite and other volcanism in the Balkans. Modified from Dimitrescu (1966). "Ophiolite" taken from local descriptions and some are largely basaltic flows. See text for details.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 1432 HERZ AND SAVU

scriptions of , much of In this paper, we cite some important another forms the Apuseni Mountains of which includes tectonic or stratigraphie works of regional geology and attempt to Transylvania (Fig. 2). The first continues to evidence for past plate history. Unfortu- provide enough Mesozoic and Cenozoic the northwest into the USSR and Czecho- nately, one of the major lacuna in many re- stratigraphic information so that a rational slovakia as the West Carpathians and to the constructions is in Romania. There, the model for the plate Tectonics history of this south into the Balkans where it is termi- sweep of the Carpathians changes from critical area can be worked out. Future nated by the Rhodope massif. The Transyl- southeast trending in Czechoslovakia to papers will describe the relation between vanian Basin is between these two chains west and south trending ir. Yugoslavia and this Romanian plate tectonics model and and east of the Apuseni Mountains. The , where the great Alpine- (1) metallogenesis and (2) petrogenesis of , west of the Apusenis, is Carpathian chain comes closest to the an- the Alpine igneous rocks. underlain by a crystalline basement of cient East European shield (Fig. 1). For ex- Paleozoic and upper Proterozoic granitic ample, in some reconstructions (see, Smith, CARPATHIAN DOMAIN AND and metamorphic rocks (Papiu and 1971; Dewey and Bird, 1970), the existence ITS EARLY HISTORY Ghenea, 1966) and was considered to rep- of ophiolites in Romania is either ignored, resent a median mass that developed be- barely mentioned, mislocated, or assigned The modern Carpathian Mountain sys- tween the Carpathian system, the Alps, and ages that are at variance with Romanian lit- tem represents one of the northern branches the Dinarides (Bleahu and others, 1967). erature (Dewey and others, 1973). Gener- of the Alpine-Dinarides-Himalayan fold The foreland of the Carpathians is bor- ally, the only reference made is to the system. Within Romania, two separate dered on the northeast by the Moldavian geological map of Romania (Bleahu and mountain chains can be distinguished: one and East European platforms, on the east others, 1967). forms the East and South Carpathians, and by Dobrogea, and on the south by the

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 PLATE TECTONICS HISTORY OF ROMANIA 1433

Domain of the Apusenis, 3,000 m of ignim- britic, weakly differentiated rhyolite was erupted, intermixed with some molasse (Bleahu and others, 1968b). In the East Carpathians, molasse consisting of lami- nated conglomerate, sandstone, violet phyl- lite, and tuffaceous sandstone was depos- ited (Bancila, 1958); in the north, in Vijeu, the molasse is 50 to 100 m thick (Bleahu and others, 1968a), but elsewhere, it is as much as 1,000 m thick (Bleahu and others, 1968b). In Dobrogea, the West Car- pathians of Czechoslovakia, southern Moesia, and the western Dinarides, calc- alkaline volcanic activity was widespread as porphyry, quartz porphyry (rhyolite), and diabase (Dimitrescu, 1966). By the end of Paleozoic time, plate collision throughout the area led to a general uplift and the widespread coarse clastics or non- deposition of the lowermost Triassic section.

Triassic. In the Carpathian chain, Lower Triassic (Seisian) sedimentary de- posits are missing or are thin detrital epicontinental and transgressive in origin Figure 6. Flysch zones, Romania. Modified from Bleahu and others (1967). Ages shown are of flysch deposits; (Fig. 7). In the Pannonian Basin, as well as associated ages of deformation are middle Cretaceous = polydeformation—mid-Late Cretaceous. Lower Creta- the southern and western part of Moesia, ceous = deformation—Laramide. Upper Cretaceous = deformation—early Styrian. Upper Cretaceous-Oligocene = acid volcanism continued, which suggests a deformation — late Styrian. Paleocene-Oligocene = deformation — post-Laramide. plate convergence of Tethys against these Moesian platform. These platform, zones In the pre-Baikalian cycle of late Precam- microplates. This, together with the fact are underlain by an ancient crystalline brian time, the Moesian platform appar- that the entire Triassic section is missing in basement that formed during Archean time ently separated from the East European the South Carpathians, suggests that by the and consolidated after the Karelian event platform, and north Dobrogea became the start of Mesozoic time much of the region (Giujca and others, 1969). By about 1,500 site of a "geosynclinal area" or inter- was a rigid sialic block. For the rest of m.y. ago, the platforms were apparently cratonic mobile zone. Stratigraphic and Triassic time, thin carbonate deposits part of one Archean-Karelian continent. structural evidence suggests a continued dominated, which is evidence for a general Evidence for the unity of Moldavia and separate existence for Moesia, north Do- shallow subsidence in Moesia and Pan- Dobrogea in Precambrian times has been brogea, and Moldavia (Paraschiv, 1972) nonia. During Ladinian and probably in obtained from cores taken in north Mol- and for the Apuseni Mountains (Savu, Carnian times, basic and ultrabasic rocks davia and central Dobrogea (Ianovici and 1965) through the end of Paleozoic time. such as diabase, gabbro and serpentinite Giu§ca, 1961). In the vicinity of Iagi appeared in places in the eastern Car- and for about 60 km to the north, crystal- Post-Paleozoic Evolution of the pathians (Cioflica and others, 1966) and in line basement was found at about 900 Carpathian System Dobrogea (Savul, 1931), and serpentinite m depth and consists mainly of Basic information on the regional geol- appeared in the western Carpathians in almandine-sillimanite—bearing paragneisses ogy, stratigraphy, and structure of Czechoslavakia (Lomize and Ploshko, with a microcline migmatite, red granites, Romania was obtained from reports and 1969; Fig. 4). The presence of these basic and basaltic dikes of Riphean age. The maps in the 1:200,000 series of Comitetul and ultrabasic rocks in the Triassic section paragneisses are petrographically similar to de Stat al Geologiei, Institutul Geologic indicates the onset of tensional faulting and those found between the Bug and Toterev (Fig. 3). In many maps, stratigraphic sec- graben formation and strongly suggests Rivers in the northern part of the Ukrainian tions of the nappes are different from each that mechanisms for plate separation had shield, and both rocks have a radiometric other. For such areas, we arbitrarily begun. Crustal thinning here must be re- age of 1,400 to 1,500 m.y. selected two sections that appeared to show lated to the westward movement of Moesia North of Constanja, granitic gneisses and the greatest diversity. The western part of a and Pannonia and their subduction of the migmatites are overlain by ari iron-rich column in Figures 7 through 12 generally Tethys plate. metamorphic series that include;; magnetite refers to a section that originated farther Also in Middle Triassic time, Moesia and quartzite, mica schists, magnetite- west than the eastern part of the column. Pannonia may have started to separate hornblende schists, and cummingtonite We have prepared maps showing the dis- from each other and continued to separate schists, all with an apparent age of 1,600 to tribution of ophiolites and other volcanism from the adjacent Moldavian platform as 1,800 m.y. and all similar in lithology and (Fig. 4), calc-alkalic rocks (Fig. 5), and part of a longer east-west trending belt that age to the Krivoi Rog Formation of the flysch deposits (Fig. 6). included the Caucasus and Crimea (Fig. 1). Ukraine. Thus, lithologic evidence from Permian. In the Balkan-Carpathian Oceanic crust and mantle appeared in Moldavia and Dobrogea, which had been area, the waning effects of the Hercynian places in the mobile intercratonic zone (the part of Moesia, suggests that the ancient were manifested as the end of sub- Cimmerian geosyncline) with associated Moesian platform was also part of the East duction and plate convergence, and molasse diabase and pillow lava (Miraufa, 1965). European platform in late Precambrian deposition and calc-alkaline volcanism Plate accretion advanced faster in the East time. were widespread (Fig. 4). In the Codru Carpathians than in Dobrogea — judging

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 1434 HERZ AND SAVU

Figure 7. Triassic stratigTapVuc sections, Romania. Thickness given in meters. Plate regime inset has no scale: arrow — movement sense; spiked circles — calc-afkalic volcanism; circle with x = malic and ophiolitic volcanism; -d- - distension axis; parallel lines = spreading center; ragged lines = consuming boundary; D = Dobrogea. by the abundance of serpentinized In places in the East Carpathians, such as form. In the Apuseni area, an ophiolite ultramafics in the former area (Chernov the area of Vulcan-Codies., volcanoclastic complex that includes basaltic pillow lava, and Slavin, 1971) — and eventually led to deposits 500 m thick are found; they in- dolerite, and associated serpentinized the development of what we will call the clude porphyritic and trachytic tuff, cut by peridovite bodies and layered gabbros was Siret Ocean. The Triassic Period closed keratophyre, trachyte, and basic porphyry emplaced. These rocks range in age from with general uplift, except for the Apuseni and arkoses and bituminous schists (Pat- Callovian (B. C. Burchfiel, 1973, written region where subsidence continued, as evi- rulius and others, 1968, p. 35). In commun.) or Early Jurassic (Savu, 1968) to denced by black limestone and microcon- Postavaru-Piatra Mare and the Fagaras Barrem, an and form a zone about 200 km glomerate of Rhaetian to Early Jurassic age Mountains of the southern Carpathians, long with a maximum width of 40 km (Bleahu and others, 1968b). We postulate from Hettangian to Toarcian time, suites of (Giujca and others, 1963; Fig. 2). In the that the Apusenis were part of the Di- basalt, diabase, olivine porphyry campton- marginal part of this zone, the ophiolites narides at this time. ite, syenite, including quartz and riebeckite rest on a pre-Alpine basement and do not Early to Middle Jurassic. In Jurassic varieties, syenite porphyry, bostonite, and contain intercalations of sedimentary rocks time, sedimentation began with a transgres- trachyte were emplaced. The sediments and at their base. In the Apusenis, as in the sion and with a much wider distribution the alkalic nature of these igneous rocks Drocea and Trascau Mountains, thin chert than during Triassic time (Arkell, 1956). suggest that crustal thinning continued to layers, radiolarite, and red argillite appear Except for the Apusenis, the Lower and develop in Moesia and Pannonia with at- near the top of the ophiolite section (Papiu, Middle Jurassic sections are, in general, de- tendant rifting and graben filling. The rate 1953), which is evidence of a pelagic envi- trital with some intercalations of limestone, of plate consumption was considerably di- ronment. The ophiolitic magma was of an marl, and marly limestone characteristic of minished around the southern and western oceanic crust and mantle origin with a nearshore facies (Fig. 8). Widespread re- edges of Moesia and Pannonia, but in all tholeiitic composition and, by differentia- gression and nondeposition took place probability, Tethyan oceanic lithosphere tion, locally developed facies ranging from throughout the Balkan Peninsula from Ba- was still sinking beneath the former plate anorthosite to granophyre. The appearance jocian through Bathonian to Oxlordian margins and was responsible for the high of this great ophiolite complex in the Apu- times (Arkell, 1956, p. 179), except for heat flow. seni Mountains, with associated radiolarite some sandy or oolitic limestone in the Car- Plate accretion was taking place between and cherty limestone juxtaposed against pathians, which may indicate a shell: edge. northern Pannonia and the Moldavian plat- sandy and oolitic limestones of the East

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 PLATE TECTONICS HISTORY OF ROMANIA 1435

Figure 8. Lower-Middle Jurassic stratigraphic sections, Romania. Thickness given in meters. Plate regime inset has no scale; legend, see Figure 7. Circle with large x = alkalic volcanism; MOL = Moldavian platform; Pan = Pannonia; Sc = South Carpathians; Si — Siret Ocean; PA = proto-Apusenis; Din = Dinarides. Carpathians, can be explained by an obduc- shale that forms typical stromatitic se- and rhyolite was widespread as was flysch tion model (Coleman, 1971). The ophiolite quences several centimeters to meters thick and wildflysch sedimentation. Plate subduc- complex originated as part of a Dinaric (Bleahu, 1962). In western Bulgaria and in tion and collision were active around the spreading ocean ridge in Jurassic time. The the pre-Balkan Mountains, flysch, tuff, Apusenis and Carpathians, but the mid- complex was emplaced at a later date by porphyry, and diorite are also present Cretaceous section in Dobrogea shows typ- plate convergence and obduction onto the (Ager, 1972). This suggests that plate con- ical shelf-edge sediments. About this time, shelf edge, which is represented by the sumption of the Siret Ocean by Pannonia the Drocea ophiolites of the Apusenis were sandy and oolitic limestone to the eas t. had started and that plate consumption also emplaced by obduction, and the Mures Late Jurassic to Early Cretaceous. Oph- was taking place south and west of Moesia fracture zone, which had started as an ac- iolitic magmatic activity in the as the Rhodope plate overrode Tethys to its tive transform, was well developed between Apusenis continued to upper Neocomian or north. The Siret Ocean that had been the Apusenis and Moesia. Aptian time when sea-floor spreading in the created by sea-floor spreading through Late Cretaceous. Flat, overthrust nappe area must have come to a close. Other evi- most of Triassic and Jurassic time between structures formed in the Carpathians from dence for a pelagic environment in the Pannonia and Moldavia was still hundreds Senonian time (about 80 m.y.) to the end of Apusenis is the deposition, in Late Jurassic of kilometers wide at this time. By Early Cretaceous time (65 m.y.). Movement sense time, of radiolarite and red argillite, as well Cretaceous time, subduction was more gen- of the nappes in the interior of the Car- as reef limestone associated with man- eral throughout the Carpathian region pathians was toward the ancient forelands ganese, on both sides of the ophiolite mas- (Figs. 9, 10). Flysch sediments (Fig. 6) were of the Moldavian platform. This movement sif. Reef limestones were deposited in the deposited, and extrusive magmatic activity coincided with trench reactivation at a time marginal marine basin between the began with abundant pyroclastic rocks, of widespread collision and subduction Moesian plate and the Moldavian platform such as basalt, spilite, andesite, oligophyre, throughout the Alpine-Dinaric- (Fig. 9). orthofelsite, dacite, and rhyolite in the Carpathian-Himalayan system. The Siret In northern Romania from latest Jurassic Apusenis (Ianovici and others, 1969). In the Ocean between Pannonia and Moldavia to Neocomian time, the >l,000-m-thick East Carpathians, spilitic rocks and flysch was again being subducted under the de- "black flysch" unit was deposited. This in- were formed in Neocomian time (Patrulius veloping Carpathian Ranges, with atten- cludes a thick sequence of spilites, chemi- and others, 1968). By mid-Cretaceous time, dant trench formation and flysch (Fig. 6). cally precipitated limestone, jasper, and red calc-alkaline volcanism of andesite, dacite, Any associated calc-alkaline volcanism in

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 1436 HERZ AND SAVU

Figure 9. Upper Jurassic-lower Lcwer Cretaceous stratigraphie sections, Romania. Thickness given in meters. Plate regime inset has no scale; legends, see Figures 7 and 8. Moe = Moesia; Rh = Rhodope; i = inactive.

Pannonia would be buried today under a in Romania over 2,500 m. The impending of Czechoslovakia (Figs. 5, 11). Volcanism thick sedimentary cover. To the southeast collision of the Rhodope plate with Moesia was also widespread in the Rhodope massif in Dobrogea, there were no apparent about this time may have been responsible as rhyolite, andesite, trachyte, trachyande- large-scale compressional movements; for the northwestern movement of Moesia. siti::, and dacite (Kamenoff, 1947). Flysch there was only the formation of fracture Upper Cretaceous andesite and lower Ter- deposition continued in trenches between systems that more or less parallel the con- tiary plutonic calc-alkaline banatites are Pannonia and Moldavia (Fig. 6) as well as tact with the ancient foreland (Fig. 10). well developed in the Sredna Gora; the between the pre-Balkans and Moesia. In the South Carpathians, no flysch had 1,000- to 1,500-m-thick Emine flysch de- Nappe structures continued to develop in developed (Fig. 6), and deformation re- veloped in the pre-Balkans (Ager, 1972) the East and North Carpathians and were sulted in the uplift of pre-Alpine blocks and shows that an active trench existed be- directed toward the craton as the Siret such as the Getic massif, which consists tween the Balkan Mountains and Moesia, Ocean was subducted by a northeast- mainly of Precambrian crystalline rocks. presumably where the last of the Tethyan moving Pannonian plate. Laramide (Banati- Austrian deformation (100 m.y.) in this plate was being subducted. With the disap- tic) volcanic activity associated with this area was apparently a result of the north- pearance of oceanic crust, the two mi- collision may be represented in the ward movement of Moesia against Tran- crocontinents collided in Paleocene time, Apusenis by the Vladeasa massif, which sylvania and the resultant collision. Crustal and a clockwise rotation of both microcon- may be the southeastern terminus of a belt thinning between the plates had taken place tinents toward their present position may whose northwestern continuation is buried through much of Triassic and Jurassic have started. Calc-alkaline volcanism also under the thick Neogene cover in Pannonia. times, as is shown by the formation of al- developed in western Moesia from con- Alternatively, Vladeasa may be close to the kalic and basaltic rocks, but there is no evi- tinued subduction of a Dinaric sea. northern terminus of a Moesian calc- dence that any great ocean had formed. . Magmatism of a sialic origin alkaline chain that developed during the Without extensive oceanic crust, no Benioff started in Paleocene time with eruptions of subduction of a Dinaric sea. Figure 5 shows zone could develop, and the collision shows banatitic calc-alkaline subvolcanic, vol- that both alternatives are viable. all the aspects of a continental, Himalay- canic, and plutonic rocks (monzonitic to These data strongly support the an type. The highest mountains are in the syenodioritic composition) in the western hypothesis (postulated by Radulescu and South Carpathians and include every peak part of Romania and the West Carpathians Sandulescu, 1973) of two plate con-

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 PLATE TECTONICS HISTORY OF ROMANIA 1437

Figure 10. Upper lower-Upper Cretaceous stratigraphie sections, Romania. Thickness given in meters. Plate regime inset has no scale; legend, see Figures 7 through 9. MZ = Mure; zone; Ap = Apusenis.

vergences in the area at this time. In the east suggests that the trench was no longer ac- origin. A calc-alkalic Neogene andesite and north, the Siret Ocean was disappear- tive after the end of Paleogene time. From from Mt. Gutai, however, showed a ratio of ing at a rapid rate as the Pannonian mi- the end of time to the start of 0.7083, which suggests significant crustal crocontinent advanced northeastward, as time, a final stage of mag- contamination (Herz and others, 1973). evidenced by the thick flysch and extensive matism erupted in the Carpathians, rep- Another Neogene volcanic arc developed calc-alkalic volcanism (Figs. 5, 6). A Di- resented by olivine basalt with alkaline or around the south and west sides of Moesia naric sea was also being subducted west of nepheline basalts. and the Apusenis, where it cuts both Juras- Moesia, as suggested by the outcrop pattern The change in volcanism from calc- sic ophiolites and the Laramide volcanics of the banatites (Fig. 5). alkalic to alkaline can be explained in two (Fig. 12). This suggests that the Apusenis Neogene. During the rest of Tertiary ways. (1) Crustal thinning was going on had become part of the Moesia-South Car- time, flysch sedimentation and nappe for- behind the Carpathian volcanic arc and led pathian plate before the end of Paleogene, mation continued around the pre- to the development of a marginal basin but probably much earlier. Carpathian trench as the last of the Siret similar to the model proposed by Karig Present evidence suggests that the area is Ocean was subducted and around the in- (1971) for marginal basins in the west still tectonically active. The seismic center termontane Transylvanian and Pannonian Pacific Ocean (Bleahu and others, 1973). of the Vrancea Mountains, around the big Basins (Fig. 6). This phase ended with the (2) The advancing Pannonian plate overran bend from the East to the South Car- formation of the Neogene molasse (Fig. the former spreading axis and a mantle pathians, reveals a sinking lithospheric 12). From late early Miocene (Burdigalian) plume of the Siret Ocean. Overriding will plate about 160 km deep (Roman, 1970), to the end of Pliocene time, widespread not change the position of a plume, and and abnormally high heat flow has been Neogene calc-alkaline volcanism de- former plumes elsewhere have been measured under the Pannonian Basin and veloped, starting with rhyolite, but was identified through the continental parts of Transylvania (Boldizsar, 1964). dominantly andesitic in character in the plates (Wilson, 1973, p. 157). Evidence for Apuseni Mountains, the East and West a mantle plume at depth and for deep frac- CONCLUSIONS Carpathians (Czechoslovakia), Hungary, turing through the crust is that olivine Microplate motions in Romania were and Rhodope (Radulescu, 1961). The lack basalt from Racoj has an initial Sr87/Sr86 relatively restricted compared to the large- of flysch deposits of Neogene age strongly ratio of 0.7043, which suggests a mantle scale plate movements associated with the

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 1438 HERZ AND SAVU

Figure 11. Paleogene stratigraphic sections, Romania. Thickness given in meters. Plate regime inset has no scale: legend, see Figures 7 through 10. Convergent arrows = Continental type collision. disappearance of the Tethys Sea. Very low formation occurred in Early Jurassic time. to their original position in the Dinarides. metamorphic grade and lack of high- At the time of formation of these ophiolites, Elsewhere, as in the Czechoslovakian Car- pressure metamorphic phenomena may be the Apuseni region must have been at some pathians, paleomagnetic determinations in part a result of the restricted mobility distance to the west, judging from the facts have shown post-Permian rotations of as and smaller scale movements. During the that (1) mid-Jurassic deposits in the Car- much as 45° (Kotasek and Krs, 1965). initial stages of Mesozoic plate separation, pathians, to the east, are typical shelf-edge Further work in this area will probably re- tholeiites, associated with radiolarite, red sediments consisting of oolitic and sandy veal rotations of various microplates. In argillite, and manganese deposits, were limestones, and (2) other large ophiolite other parts of the Mediterranean, between erupted (Fig. 4) and formed pillow lavas in bodies are abundant in the Alpine- Triassic and Cretaceous times, other mi- places. In the East Carpathians and north Dinaric-Himalayan chain and not in the croplates also underwent rotations with re- Dobrogea, mafic volcanism started in Carpathians. The Apusenis may have been spect to Europe (Williams and McKenzie, Ladinian time as part of a belt that ex- part of a Dinaric spreading system; the Di- 1971), presumably in response to the tended eastward through Crimea and the naric ophiolites are also Jurassic in age, and differential movement of the Eurasian and Caucasus. Alkalic volcanism followed in both include cherty limestones and African plates. Rotation in the Balkan area some places. This volcanic activity may rep- radiolarite formations (Smith, 1971). We might also be due to this differential move- resent crustal thinning and tensional fault- infer that the Apuseni area was transported ment and to the plate collision of African ing, and at least in the northwestern part of to its present position along transform elements, such as Rhodope. Some deep the belt, plate separation from Moldavia faults that are represented today, in part, by fracturing in Dobrogea, more or less paral- and the may have the deep Mure§ fracture zone between the lel to the craton, may have also been caused actually started. Spreading here eventually Apuseni Mountains and the South Car- by the Rhodope collision. led to the formation of the Siret Sea, which pathians. This implies a displacement of During the later arc-trench (geosynclinal) must have reached a width of hundreds of several hundreds of kilometers of the Apu- development in Late Jurassic and Early kilometers by the end of Jurassic time. Plate seni block from the Dinarides to its present Cretaceous times, the platform facies in the consumption of Tethys was taking place by position. Carpathians was succeeded by flysch westward-moving Pannonia and Moesia It should also be noted that if the deposition, which was accompanied by (Fig. 7). Apusenis were translated eastward, they arc-trench volcanism as Pannonia moved In the Apuseni Mountains, ophiolite were at the same time rotated with respect northeastward to close the Siret Sea. The

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 PLATE TECTONICS HISTORY OF ROMANIA 1439

W V \ r' b— 50:70 / 250 - 0 / 600 - d 1505" / I500-30SQ 125-475 1000-3000 i 8501750 / I500-2I0Ö 550=13ÖÖ'J-JJ / l50-250d>"' ' IE0- -b / 400 -0 / : 40-125 '50-300 •d 4QQ 100- <3 200 50-60 3000 Wïi 10- 600 r \ b-: dv .800 . IOO.OJH 1700

LEGEND

sedimentory rocks igneous

conglomerate I [limestone rhyolite,granite - 9 +++ sandstone m " with jasper andesite -a AAA shale, etc. 1» I " with bitumen basalt -b * * Y carbonaceous CD marly Is. 50 100 km •1 - cool dacite,gronodiorite -d XXX El oolitic Is. " salt,etc. trachyte -t V V V I - I sondy Is. -• - colc-shole gabbro,u-mafics •i (ZHfresh water Is. b. o wildflysch Y A dolomite

Figure 12. Neogene straugraptiic sections, Romania. Thickness given in meters. Plate regime inset has no scale; legend, see Figures 7 through 11.

TABLE 1. AGREEMENT BETWEEN DEWEY AND OTHERS (1973) principal started in Late AND THIS PAPER FOR OPENING OF THE ATLANTIC Cretaceous time and was represented here by subduction and collision with extensive Dewey and others (1973) This paper structural deformation but little or no 210 m.y. metamorphism. Consequently, although Start of extension 1n East Carpathians, calc-alkaline volcanism (Fig. 5) and flysch Dobrogea belts (Fig. 6) are well developed in the Car- 180 m.y.

pathians, there are no known glaucophane Opening of mid-Atlantic Continued extension in East Carpathians schists (blue schists), which are characteris- Africa moves southeast, counterclockwise rotation Formation of Siret Ocean tic of the Franciscan group of the western United States and many parts of the 148 m.y. Alpine-Himalayan chain. Africa moves northeast, counterclockwise rotation Diñarle spreading centers eastward translation, Apusenis Paleocene plate convergences, presum- ably a continuation of Rhodope-Moesia 80 m.y. and Pannonia-Moldavia convergences led North Atlantic fast opening Siret, Dlnaric, Tethys dosing to a second stage of plate-margin Approach of Rhodope plate—an African Africa moves west-northwest, counterclockwise rotation element phenomena, including the formation of the

calc-alkalic banatites (Giujca and others, 63 m.y. Continued closing Siret, Diñarle, Tethys 1966). Flysch deposits formed in the arc- Slow opening of entire Atlantic; Africa moves trench system, whose continued evolution west-southwest, counterclockwise rotation led to Neogene volcanic arcs and molasse. 53 m.y. We offer Table 1 as a model for a critical Africa moves north, counterclockwise rotation Rhodope-Moesian collision, disappearance of Tethys; South Carpathians continental area of the Carpathian-Alpine-Dinaric- collision; continued closing Siret, Himalayan system, with its complex history D1nar1c of microplates, short-lived spreading cen- 9 m.y. ters, transform faults, and consuming Africa moves north Continued north and northeast movement boundaries, and as a refinement of other microplates

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021 1440 HERZ AND SAVU

models that have recently appeared (Dewey Geogr., ser. Geol., v. 10, p. 75-97, McKenzie, D. P., 1969, Speculations on the con- and others, 1973; Radulescu and Bucureçti. sequences and causes of plate motions: Sandulescu, 1973; Bleahu and others, Coleman, R. G., 1971. Plate tectonic emplace- Royal Astron. Soc. Geophys. Jour., v. 18, p. 1973). The detailed geological data used in ment of upper mantle peridotites along con- 1-32. our study made such a refinement possible. tinental edges: Jour. Geophys. Research, v. 1970, Plate tectonics of the Mediterranean 76, p. 1212-1222. region: Nature, v. 226, p. 239-243. Still, there is much missing information, Dewey, J. F., and Bird, J. M., 1970, Mountain Minu;a, O., 1965, Devonianul çi Triasicul din especially regarding the detailed movement belts and the new global tectonics: Jour. colinele Mahmudiei (Dobrogea): D. S. of the microplates, and future studies of Geophys. Research, v. 75, p. 2625-2647. Comm. Geol., Bucurejti, v. 52. paleomagnetism should shed much light on Dewey, J. F., Pitman, W. C, III, Ryan, W.B.F., Miraufa, O., Mutihac, V., and Bandrabur, T., this. In all humility, we must agree with the and Bonnin, J., 1973, Plate tectonics and 1968, Tulcea, Harta Geologica, nota recent statement that any model proposed the evolution of the Alpine System: Geol. explicativa.38: Bucurejti Inst. Geol., 32 p. at this time may be incorrect (Dewey and Soc. America Bull., v. 84, p. 3137-3180. [Romanian and French]. others, 1973, p. 3174), but we believe that Dimitrescu, R., 1966, Beiträge zur Kenntnis der Morgan, W. J., 1968, Rises, trenches, great faults enough data has been presented here so that magmatisch-tektonischen Verhältnisse im and crustal blocks: Jour. Geophys. Re- future syntheses can be constructed more Karpatisch-Balkanischen räum: Acta Geol. search, v. 73, p. 1959-1982. Hungary, v. 10, p. 357-360. Papiu, V. C., 1953, Cercetari geologice in easily. Dimitrescu, I., and Sandulescu, M., 1970, Harta masivul Drocea (Munfii Apuseni): Bui. St. Technica, Foaia #6: Bucurejti Inst. Geol. Acad. R. P. Roman., Bucurejti, v. 1. ACKNOWLEDGMENTS Gherasi, N., Muresan, M., Lupu, M., Stancu, J., Papiu, V. C., and Ghenea, C., 1966, 16. Arad, John F. Dewey, A. J. Erickson, and Paul and Savu, H., 1968, 25. Deva, Harta Harta Geologica, nota explicativa: R. Pinet discussed the implications of this Geologica, nota explicativa: Bucurejti Inst. Bucurejt: Inst. Geol., 25 p. [Romanian and paper and critically read it; Marcian Geol., 64 p. [Romanian and French], French]. Bleahu, Dan Radulescu, and Sergiu Peltz Giu§cä, D., Cioflica, G., and Savu, H., 1963, Paraschiv, D., 1972, Sur la distribution des gise- discussed the Romanian geology and vari- Vulcanismul mesozoic din Masivul Drocea: ments d'hydrocarbure dans l'avantpays des V. Cong. Asoc. Geol. Carpato-Balc, II See., Carpates roumaines: Internat. Geol. Cong., ous plate models; and B. C. Burchfiel and p. 31—44, Bucurejti. 24th, Montreal 1972, sec. 5, p. 104. A. G. Smith also critically read the paper. 1966, Caracterizarea petrologica a provin- Patrulius, D., Dimitrescu, R., and Gherasi, N., The Romanian Academy and Ministry of ciei banatice: An. Com. Geol., Bucurejti 1968, 28. Brajov, Harta Geologica, nota Mines, Petroleum, and Geology and the Inst. Geol., v. 35, p. 13—45. explicativa: Bucurejti, Inst. Geol., 68 p. United States Academy of Sciences made Giujca, D., Savu, H., Bercea, I., and Kräutner, [Romanian and French], our collaboration possible. H., 1969, Sequence of tectonomagmatic Radulescu, D., 1961, Contribufii la cunoasterea pre-Alpine cycles on the territory of caracterelor chimice aie rocilor vulcanice Romania: Acta Geol. Hungary, v. 13, p. tinere de la interiorul arcului carpatic: REFERENCES CITED 221-234. Acad. Romania Studii çi Cercetari Ager, D. V., 1972, Summer field meeting in Bul- Herz, N., Jones, L. M., Savu, H., and Walker, R. Geologie, Bucureçti, v. 6. garia, 1971: Geol. Soc. London Proc., v. 83, L., 1973, Sr^/Sr86 analyses of ophiolitic and Radulescu, D., and Sandulescu, M., 1973, The p. 239-267. related rocks, Drocea Mountains, plate-tectonics concept and the geological Arkell, W. J., 1956, Jurassic geology of the Romania, in Abstracts Int. Symp. Vol- structure of the Carpathians: Tec- world: New York, Hafner, 806 p. canism and Assoc. Metall., Bucharest: p. tonophysics, v. 16, p. 155-161. Bancila, I., 1958, Geología Carpafilor Orientali: 72-75 (also in press, Bull. Volcanol.) Roman, C., 1970, Seismicity in Romania — Evi- Ed. jtiinfifica, Bucurejti. Ianovici, V., and Giujca. D., 1961, Date noi dence for the sinking lithosphère: Nature, v. Bleahu, M., 1962, Cercetari geologice In bazinul asupra fundamentului cristalin al Podijului 228, p. 1176-1178. superior al riului Ruscova (Munjii Moldavanesc ji al Dobrogei: Acad. Savu, H., 1965, Masivul eruptiv de la Birzava Maramurefului): D. S. Comm. Geol., Romania Studii ji Cercetari Geologie, (Munfii Drocea): Bucurejti, Memoriile Bucurejti, v. 45. Bucurejti; v. 6, p. 153-159. Camm. Geol., v. 8. Bleahu, M., Patrulius, D., Radulescu, D., Saulea, Ianovici, V., Giu§ca, D., Ghijulescu, T. P., Bor- 1968, Considérations concernant les rela- E., and Savu, H., 1967, Harta Geologica, cos, M., Lupu, M., Bleahu, M., and Savu, tions stratigraphiques et la pétrologie des nota explicativa: Bucurejti Inst. Geol., 27 p. H., 1969, Evolufia geologica a Munfilor ophiolites Mésozoiques de Roumanie: An. [Romanian and French], Metaliferi: Acad. Romania Studii ji Com. Geol., Bucurejti Inst. Geol., v. 36, p. Bleahu, M., Bombifa, G., and Kráutner, H. G., Cercetari Geologie, Bucurejti, 741 p. 143-175. 1968a, 4. Vi^eu. Harta Geologicá, nota Kamenoff, B. G., 1947, Carte Géologique de la Savul, M., 1931, Eruptiunile de diabaze din nor- explicativa: Bucurejti Inst. Geol., 54 p. Bulgarie: Sofia, Dir. Rech. Geol. et Min. en dul Dobrogei: D. S. Inst. Geol. Român., [Romanian and French], Bulgarie, scale 1:500,000. Bucureçti, v. 18 (1929-1930). Bleahu, M., Borcos, M., and Savu, H., 1968b, Karig, D. E., 1971, Origin ard development of Smith, A. G., 1971, Alpine deformation and the 17. Brad, Harta Geologica, nota marginal basins in the western Pacific: Jour. oceanic areas of the Tethys, Mediterranean, explicativa: Bucurejti Inst. Geol., 60 p. Geophys. Research, v. 76, p. 2542—2561. and Atlantic: Geol. Soc. America Bull., v. [Romanian and French]. Kotâsek, J., and Krs, M., 1965, Palaeomagnetic 82, p. 2039-2070. Bleahu, M., Boccaletti, M., Manetti, P., and study of tectonic rotation in the Carpathian Vasilescu, A., Murejan, M., Popescu, I., Peltz, S., 1973, Neogene Carpathian arc: A Mountains of Czechoslovakia: Palaeog- Sandulescu, J., Popescu, A., and Bandrabur, continental arc displaying the features of an raphy, Palaeodimatology, Palaeoecology, T., 1968, 20. Odorhei, Harta Geologica,' "island arc": Jour. Geophys. Research, v. v. 1, p. 39-49. nora explicativa: Bucurejti, Inst. Geol., 68 78, p. 5025-5032. Le Pichon, X., 1968, Sea floor spreading and p. [Romanian and French]. Boldizsár, T., 1964, Terrestrial heat flow in the continental drift: Jour. Geophys. Research, Williams, C. A., and McKenzie, D., 1971, The Carpathians: Jour. Geophys. Research, v. v. 73, p. 3661-3697. evolution of the north-east Atlantic: Na- 69, p. 5269-5275. Lomize, M. G., and Ploshko, V. V., 1969, Ul- ture, v. 232, p. 168-173. Chernov, V. G., and Slavin, V. I., 1971, Upper trabasic rocks of the main Maramurej fault Wilson, J. T., 1973, Mantle plumes and plate Triassic of the Soviet Carpathians: Akad. (eastern Carpathians): Geotectonics, v. 2, p. mo rion: Tectonophysics, v. 19, p. 149—164. Nauk SSSR Doklady, v. 200, p. 107-109. 117-125. Cioflica, G., Patrulius, D., lonescu, J., Udubaja, Lupu, M., Borcos, M., and Dimitrescu, R., 1967, MANUSCRIPT RECEIVED BY THE SOCIETY JUNE 1, G., 1966, Les ophiolites triasiques alloch- Turda, Harta Geologica, nota explicativa. 1973 tones des Monts Perjani (Carpates Orien- 18: Bucurejti Inst. Geol., 43 p. [Romanian REVISED MANUSCRIPT RECEIVED FEBRUARY 22, tales): Rev. Roum. Geol., Geophys., and French]. 1974

Printed in U.S.A.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/9/1429/3429071/i0016-7606-85-9-1429.pdf by guest on 28 September 2021