The age of the Dinaride Ophiolite Belt – derived olistostrome mélange at the northern slope of Moračka Kapa (Montenegro)

This paper presents the first results of a palynological investigation of the Dinaride Ophiolite Belt – derived olistostrome mélange at the northern slope of Moračka Kapa (Montenegro). The analysis of microfloral association provided a reconstruction of the Late Jurassic sedimentation conditions and depositional environment in the Morača Kapa Unit. The samples (8) collected from the different parts of ophiolite matrix yielded palynomorph assemblages (fossil spores, pollen grains and dinoflagellates) of the Upper Jurassic age. The uppermost part of the ophiolite suite on the presented palynomorphs could also indicate the lowermost Lower Cretaceous. These palynological results provide a very interesting framework of these widespread, but poorly stratigraphically understood sediments. The paleoecological results suggest humid and subtropical conditions in the hinterland.


Introduction
The Moračka Kapa Unit is located between the Mesozoic cover overlying the Adria-derived Dalmatian-Herzegovinian composite terrane and the East Bosnian-Durmitor terrane which continues towards the southeast to the Korab terrane.It is composed of fragments to blocks (up to few decameters is size) of limestones, sandstones, basalts and serpentinites, all set in a shaly and marly matrix.It is very similar to the Jurassic olistostrome mélange of the Dinaride Ophiolite Belt, formerly named the Diabase-chert formation.The Moračka Kapa unit represents an isolated part of the detrial subduction trench assemblage of the western margin of the Dinaride Ophiolite Belt (KARAMATA et al. 2010).
The purpose of this study is to present the microfloral characteristics of the Upper Jurassic sediments (ophiolite mélange) with special emphasis on their stratigraphic position, correlation with other similar palynological assemblages in Serbia and aboard and their geodinamic implications.
The Moračka Kapa Unit was first mentioned by KALEZIĆ et al. (1966).Given that the position of the unit is absolutely strange in this surrounding, its geological properties and stratigraphic position deserve a special our attention.All the field work, petrographical investigation of selected samples, paleontological investigation and trace element analysis were coordinated by S. KARAMATA.ča Kapa ophiolite mélange in the valley of the Morača River (Dragovića Polje, Velje Duboko, Montenegro; Fig. 1).The samples from the matrix in Morača ophiolite mélange were collected during earlier field works by S. KARAMATA and M. PAJOVIĆ, who studied these localities in great petrological and geological detail.Figure 1 shows the location of the exposed surface, which was discovered at Dragovići Polje and the position of the investigated samples.
Palynological investigations are performed on the samples that were taken from the sequences without any other microfossils.Due to the lack of ammonites and other macro-fossils, stratigraphic control was not possible for the investigated succession.

Methods and aims
About 200 grams of each sample were taken for maceration.Palynomorphs were observed on isolated kerogen concentrates from different rock samples.The samples were initially treated with the classical 30 % HCL (removal of carbonate) and later with 40 % HF (3-5 days) to remove siliceous matter.Subsequently, the material was washed and submitted to separation (ZnCl 2 ; d = 1.9-2.0g/cm³).
Occasionally, the separated kerogen concentrate was also treated to conditional acetolysis and oxidation for about three days (NaCl+HNO 3 ; KClO 3 +HNO 3 ; the staining efect on exines; ERCEGOVAC, 1996).Afterwards the material was again subjected to repeated washing to remove all traces of the acids.The macerated detritus was finally treated with 10 % KOH to dissolve the humic substances and clear the palynomorphs.Some of the most significant and well preserved palynomorphs are illustrated on the Plates I-III.The prepared slides and the original rock samples are kept in the Palynological Laboratory of the Faculty of Mining and Geology, Belgrade.
The species Licopodiumsporites clavatoides and other form with typical reticulum on the distal face is quite infrequent in the presented association.Its presence, however, has certain biostratigraphic importance.The common elements of the late Jurassic in this assemblage include Ischyosporites variegatus, Perinopollenites elatoides and Leptolepidites verrucatus.
The absence of typically Lower Cretaceous elements (Trilobosporites, Appendicisporites, Cicatricosisporites, Schizosporis, Plicatella, Cooksonites and others) in investigated samples is very characteristic.VAKHRAMEEV et al. (1973) believe that the transition from the Volgian (Tithonian) to the Berriasian (Lowermost Cretaceous) was characterized by the first occurrence of canaliculate spores of the type Cicatricosisporites, whereas in the Indo-European paleofloral province the genus Appendicisporites occurs in the Lower Cretaceous (Valanginian).The biostratigraphicaly significant presence of the Upper Jurassic taxa such as Klukisporites, Callialasporites, Concavisporites, Perinopollenites and Araucariacites, indicates to a Late Upper Jurassic, probably Kimmeridgian to Tithonian age for the Morača ophiolite mélange.
The coniferous miospores are represented by nonsaccate, monosacate and bisaccate elements viz., Araucariacites, Classopollis, Callialasporites, Alisporites, Abietinaepollenites, Vitreisporites and Podocarpidites.A quantitative analysis the forms of the microflora from the integral palynological association showed the different frequencies of the various taxa.It was concluded that Araucariaceae, Podocarpaceae and Calliala grains among the Gymnosperms, and Cyatheaceae, Gleicheniaceae, Lycopodiaceae and Osmundaceae among the Pteridophytes represent the most important families of the Morača microfloral assemblage.A vegetation of dominating conifers from the family Araucariaceae and Classopollis group existed in the land habitatus in the prominent places on islands, under a then warm climate.The species Callialasporites dampieri is a representative element for the middle-upper part of the Mesozoic in Europe, North America, Australia, China and India.
This assemblage is also characterized by gymnospermous pollen grain among which are the forms with two sacci, such as Quadraeculina, Abietinaepollenites, Podocarpidites, etc.Of lower abundance are the pollen grains of the monosaccate coniferales, such as Araucariacites, Callialasporites, Classopollenites, etc.In addition, there are some monosaccate coniferales, such as Cerebropollenites, together with a few monocolpate pollen grains of Ginkgocycadophytus nittidus.
The species Eucommidites troedsonii has been also recorded from the Morača assemblages, as a characteristic species of the young Mesozoic of the North Hemisphere; Araucariacites australis is distributed in the Upper Jurassic and Early Cretaceous in China, in limited numbers, but it is a characteristic species occurring in great abundance in the Middle Jurassic of England, Sweden and some others countries in Northwest Europe.
The Upper Jurassic (mostly Tithonian) in most of the localities over the world contain dinoflagellates (Gonyaulax, Pareodinia, Apteodinium, etc.;BERGER 1986;DAVEY 1982) and specific plankton remains (Acritarcha and Incertae sedis).The spore-pollen association of the Morača contain a low amount of marine microplankton.Late in the Tithonian, the phytoplankton content was much lower than in the Kimmeridgian, while spores and pollen grains of terrestrial plants are higher.The dynocyst assemblage reported the Upper Jurassic age of the investigated samples.The species Gonyaulax jurassica and Pareodinia ceratophora are scare in lowermost parts of the Lower Cretaceous Unit.The depositional environment is partially marked by the different plankton forms (Dinoflagellates, Acritarchs and Palynoforaminifers).The rare appearance of the low preserved genus Sentusidinium most probable point to the Upper Jurassic.On the whole the presence of the dynocyst assemblage predominantly reports the Upper Jurassic age of the investigated samples.
The microflora described from the ophiolite mélange of the Morača shows a remarkable analogies with the palynological assemblage of the bauxite deposits at Biočki Stan (north of Nikšićka Župa), which are located in the southern part of the Dinaric Carbonate Platform of Montenegro.The mentioned sedimentary rocks were formed during the Upper Jurassic-Lowermost Cretaceous (mainly late Kimmeridgian; ERCEGOVAC et al. 1996) 1979), Canada (POCOCK 1967, 1970) and India (SRIVASTAVA 1966).

Some remarks about the palynological criteria for the recognition of the Jurassic-Cretaceous boundary in western Europe
Many references were originally demonstrated that significant palynologic differences exist between the The age of the Dinaride Ophiolite Belt -derived olistostrome mélange at the northern slope of Moračka Kapa major Jurassic-Cretaceous formations.NORRIS (1969,1973), BATEN (1973), MORGAN (1980) for example, recognized three principal microflora assemblages close to the Jurassic-Cretaceous boundary, as follow: The microflora of Lower-Middle Thithonian is very restricted in composition containing only the following species over and above the background species: Cyathidites minor, C.

Paleoecological reconstruction
The analysis of spores and pollen grains, also of dinoflagellate remains, provides for the reconstruction of land vegetation on the surrounding islands.
The younger Jurassic microflora from the Morača area is representative of a typical continental flora of island archipelagos in the tropical regions of the Tethys.From the palynological assemblage two main types of land vegetation were distinguished on the islands.
a. Wet coastal regions of islands with shallow water formations were characterized with vegetation of dominant ferns (Klukisporites, Deltoidospora and Lycopodiacidites) and some seed ferns (Cycadophytes).
b. Prominent areas on the islands had more xerophyte flora which is evidenced by the abundance of conifers (mostly pollen grains of Araucaria and Classopollis).Macrofloral remains of Bracyphyllum and Pagiophyllum were not recorded.The presence of Classopollis pollen indicates their xerophitic nature.However, the presence of Classopollis pollen can be related to both arid and humid climates of high littoral areas.Its occurrence in Mesozoic rocks indicates a warm climate (VAKHRAMEEV 1970).Similar climatic conditions are suitable also for plants producing pollen of Araucariacites and Callialapollenites types; in many examples, they are found together in Jurassic and Lower Cretaceous sedimentary rocks.The presence of the families Gleicheniaceae and Schizaceae in the Uppermost Jurassic and Lower Cretaceous indicates humid climate.
c.The depositional environment is also marked by a sparse form of dinoflagellatae, acritarchs and palynoforaminifers.As has already been mentioned, the occurrence of phytoplanktonic -algal remains is associated with an aquatic environment, which indicates a great influence of marine sedimentation conditions during the formation of these sediments.
The palynological assemblage could be used for consideration concerning the paleoclimate during the sedimentation of the investigated sequences in the Morača area.Transitional tropical-subtropical climatic belts during Upper Jurassic were concluded.
In the Upper Jurassic and Lowermost Cretaceous, in the stil large Tethys, continental flora of the Tethyan phytogeographic realm existed on many archipelagos situated between the south "Laurasian Phytogeographic Realm" ("Indo-European relm"; VAKHRAMEEV 1975) in the north and the north "Gondvana Realm" (African continent) in the south (BRENNER 1976).Continental floras on archipelagos in the realm of the west Tethyan intraoceanic carbonate platforms, at the time were much closer to the African continent, during the Jurassic and Lower Cretaceous ("separate Tethyan phytogeographic realm"; PANTIĆ et al. 1983).

Conclusion
Based on the first palynological investigation of the Moračka Kapa ophiolite mélange (Montenegro), the conclusions are as follows: From the possible affinity of the palynomorphs, it may be deduced that in the Upper Jurassic, the Morača area was not rich in floras, which include Pteridophytes belonging to families such as Lycopodiaceae, Selaginellaceae, Osmundaceae, Dicksoniaceae, Cyatheaceae, etc.Among the Gymnosperms, are those plants of Cycadaceae, Ginkgoaceae, Pinaceae, Podocarpaceae and Araucariaceae.From the ecological environment of the parent plants, it was inffered that this region at that time was under a warm and humid subtropic to temperate climate.
All these paleontological data contribute to an elucidation of the characteristic late Jurassic vegetation from the Tethyan phytogeographic province.The younger Jurassic microflora from Morača area is representative of a typical continental flora of island archipelagos (near shore environment) in the subtropical-tropical regions of the Tethys.The microflora described is of special paleo-and phytogeographical interest and shows remarkable analogies with mediterranean and south-alpine floras of the Tethys, but differs from the north-pennine flora, which may belong to the Laurasian floral realm.

Старост Динаридског офиолитског појаса -меланж олистостроме на северној падини Морачке Капе (Црна Гора)
Taking into account all the mentioned palynological data it was concluded that the Upper Jurassic age of the Moračka Kapa Unit coresponds to late phases of the Dinaride Ophiolite Belt foramation.The microflora of the obtained palynological investigation on the Moračka Kapa ophiolite mélange allows a new consideration in relation to Upper Jurassic-Lowermost Cretaceous boundary.The available data concerning the age of the Moračka Kapa Unit are very important for a new interpretation of palaeogeographic and geodynamic events in this part of Tethys during the Upper Jurassic (KARAMATA et al. 2010).