Micropalaeontologic and palaeofloristic content of Sarmatian from southern Moldavian Platform backbulge depozone

Transcription

1 Micropalaeontologic and palaeofloristic content of Sarmatian from southern Moldavian latform backbulge depozone Mihai BRÂNZILĂ 1, Gabriel CHIRILĂ 1, Mihaela JITARU 1 1 University Al. I. Cuza from Iaşi, Departament of Geology, Bd. Carol I, nr. 20A, , Iasi, Romania, mib@uaic.ro, gabiflogeoc@yahoo.com Abstract. Southern part of the Moldavian latform has been developed in comple conditions, partially similar, with northern part, in a marine environment corresponding to the last stage of evolution of the foreland basin of the Eastern Carpathians, with an obvious tectonic control. In Stăniţa-Vlădnicele borehole were identified microfauna taas as: Quinqueloculina karreri, Q. consobrina, Elphidium macellum, E. minutum, E. punctatum, E. crispum, E. aculeatum, E. regina regina, E. regina caucasica, Articulina problema, A. glabra, A. sarmatica, orosononion subgranosus confirming the presence of the Sarmatian, starting with Buglovian, Volhynian and most of the Bessarabian. Identified palynomorphs from the analyzed samples are represented by taa as: ityosporites labdacus, ityosporites alatus, ityosporites insignis, inuspollenites miocaenicus, Abiespollenites sp., Myricipites bituitus, Tricolpopollenites liblarensis, Tricolporopollenites henrici, Carpinipites carpinoides, Engelhardtioides microcoryphaeus, Leiotriletes sp. a.o. The method used for paleoclimatic estimations is Coeistence Approach. The values calculated by us, using coeistence approach method are: MAT C, MA mm/yr, WMT C, CMT C. Keywords. Sarmatian, Moldavian latform, backbulge, micropalaeontology, palynomorphs. Introduction Analyzed samples, from this study, are from Stăniţa-Vlădnicele borehole (Neamţ County) located nearby the tectonic limit, which divide Moldavian latform from Bârlad latform by Fălciu lopana fault (Ionesi, 1994) (Fig. 1). Lithological column of the well have intercepted entirely Sarmatian deposits, from the limit of the Badenian anhydrite until the Cryptomactra clays (lower Bessarabian and the beginning of the upper Bessarabian).

2 Fig.1 Location of Stăniţa-Vlădnicele borehole Geological settings The Moldavian latform supported a foreland type basin evolution during the Sarmatian, as the last phase within the transformation of the Carpathian geosynclinal area. There have been identified characteristic depozones (wedge top, foredeep, forebulge and backbulge) that due to particular facial conditions allowed the evolution of some specific faunal assemblages (Grasu et al., 2002). Within all non-biotic factors, the water salinity evolved towards a freshwater one, representing along with the sedimentary process, the main cause that had a great influence on the foraminifers assemblages (Brânzilă, 2005). The Intra-Volhynian tectogenesis, especially taking part in the eternal zone of the Carpathians, have strongly affected the evolution of the aratethys basins. In the terminal part of the Badenian, the Moldavian latform has functioned as continental area, the sedimentation process lasting until the lower Sarmatian (Buglovian)( Brânzilă, 2005, Brânzilă & Ţabără, 2005) Beginning with the Lower Sarmatian, in the Eastern Carpathian foreland, because of the advancement of the orogeny above the top of the Moldavian latform, a series of characteristic depozones were outlined. Based on sedimentological criteria, from west to east, four depozones have been identified: wedge-top, foredeep depozone, forebulge and backbulge. The basinal waters have a much lower salinity as compared with that during the Badenian (Brânzilă, 1999; Grasu et al., 2002). Southern part of the Moldavian latform has been developed in comple conditions, partially similar, with northern part, in a marine environment corresponding to the last stage of evolution of the foreland basin of the Eastern Carpathians, with an obvious tectonic control. Deposits of this interval belong to the first stage of evolution of the foreland basin where the subsidence was polarized from North-East to South-West and was inducted by the influence of the Carpathian thrust (Ionesi, 1994,

3 Ionesi et al., 2005). In such conditions we have seen the presence of the microfauna and paleoflora assemblage corresponding to the backbulge depozone. Fig. 2 Lithologic column of Staniţa-Vlădnicele borehole.

4 Micropalaeontological assemblage Micropalaeontological assemblage identified in samples from Stăniţa-Vlădnicele borehole has two aspects, distinctive for Miocene biofacies from Moldavian latform; one aspect regarding marine and the second one related to brackish deposits. In the sample 1 from 975 m, located under Badenian anhydrite, micropalaeontological content is eclusively marine been represented by benthic and planktonic foraminifera, which developed under normal salinity, with many taas and many individuals. From this sample were determined: Uvigerina perornata, Bulimina elongata, Globigerina brevispira, Orbulina universa, Cibicides lobatulus, C. dutemplei, Entoselenia marginata, Melonis pompilioides, ullenia bulloides, Sphaeroidina austriaca, Spiroplectamina sp., Quinqueloculina sp. In the deposits located above Badenian anhydrite, the lithology is predominantly composed of shale, sands, sandstones with thin lamination of limestone. Samples 1-9, from the interval m are attributed to Sarmatian. Micropalaeontological assemblage has brackish characteristic, and the number of taas is lower. Cibicides taa (Cibicides badenensis, C. lobatulus) are present only in sample 9 (950 m), alongside with reworked taas: Ammonia beccarii, Quinqueloculina sp., and Globigerina sp. In the analyzed samples between 140 and 890 m, although micropalaeontological assemblage is poor and is represented by miliolidae and unionidae; Quinqueloculina karreri, Q. consobrina, Elphidium macellum, E. minutum, E. punctatum, E.crispum, E. aculeatum, E. regina regina, E. regina caucasica, Articulina problema, A. glabra, A. sarmatica, orosononion subgranosus. Micropalaeontological assemblage identified in the analyzed samples from Stăniţa-Vlădnicele borehole is assigned to Badenian (sample 310 from 975 m) and to Sarmatian (samples 1-9 from 140 to 975 m), been possible even an distribution on stages. The assemblage determined from sample 9 (from 950 m) can be attributed to Buglovian, samples 5-8 (from m) are assigned to Volhynian and samples 1-4 (from m) are attributed to Bessarabian. Table 1. Micropalaeontological assemblage from analyzed samples of Stăniţa-Vlădnicele borehole Taa Uvigerina perornata ischw. Bulimina elongata d'orb. Globigerina brevispira Subb. Orbulina universa d'orb. Cibicides dutemplei (d'orb.) Entoselenia marginata (W et B) Melonis pompilioides F.et H. ullenia bulloides (d'orb.) Sphaeroidina austriaca d'orb. Spiroplectamina sp. Quinqueloculina sp. Cibicides lobatulus W.et J. Cibicides badenensis d'orb. Quinqueloculina karreri Reuss. + +` + Quinqueloculina consobrina d'orb Articulina problema Bogd Articulina sarmatica (Karrer) Articulina glabra (Cushm.) Elphidium macellum (F.et M.) Elphidium minutum Reuss X X X

5 Elphidium punctatum + Elphidium crispum (Linne) Elphidium aculeatum d'orb Elphidium regina regina d'orb Elphidium regina caucasica Bogd orosononion subgranosus (Egger) orosononion martkobi Bogd Ammonia beccarii L Legend high frequency; + low frequency alynological study Analysis of the pollen content from samples is the principal technique available for determining vegetation response to past terrestrial environmental change. The technique has been in use for nearly a century, initially as a method for investigating past climatic changes. More recently, the importance for vegetation change of processes such as human impact, successional change and other biotic and abiotic factors have been recognized. The palynological study was made using 10 collected from Stăniţa- Vlădnicele borehole (RBN 4 borehole) from interval between m (Fig. 2). The quantity of sediments for analysis was approimately 50 g for each sample. Those have been treated with HCl (37%) to remove the carbonate and afterward with HF (48%) to remove the silicate minerals. The separation of palynomorphs from the residue resulted from the chemical reaction described above, was made with centrifugal action using as heavy liquid ZnCl 2 with density 2.00 g/cm 3. The organic fraction resulted was inserted in a miture of glycerine and gelatine, 1-2 drops been mounted on the palynological shim. The visualisation of the palynomophs was accomplished with a microscope with transmitted light Leica DM1000, using the amplification of 100, 400. alynological assemblage alynological assemblage present in the Stănita Vlădnicele borehole (Table 2) is represented by a dinoflagelate assemblage (Operculodinium, Spiniferites, Spirogyra, Tytthodiscus) present in low quantities and a continental assemblage with Gymnospermatophytae (Abiespollenites, ityosporites, Cedripites, Inaperturopollenites, odocarpidites, Zonalapollenites), Angiospermatophytae (Graminidites, Caryapollenites, Engelhardtioidites, Intratriporopollenites, Tricolporopollenites), teridophytae (Laevigatosporites, Leiotriletes, olypodiaceoisporites, Verrucatosporites). From continental assemblage dominante are Gymnospermatophytae taas (ityosporites) and Angiospermatophytae taas (Caryapollenites and Tricolporopollenites). Dinoflagellate assemblage. This assemblage is mainly composed from Operculodinium, Spiniferites, Spirogyra and few reworked species of hytoplankton. Higher percentage and diversity is present in sample 3, from 485 m (Fig. 3). Operculodinium is generally reported as a cosmopolitan species that might have low relative abundances in the tropics and high relative abundances in regions with cold/temperate waters such as the North Atlantic (Wall et al. 1977; Marret & Zonneveld, 2003). This species is distributed within a very broad range: temperature ( C and C) and salinity ( / 00 ). Continental assemblage. Ivanov et al., 2002, 2007, showed that vegetation of the middle and upper Badenian of Forecarpathian basin (central aratethys, NW Bulgaria) was characterized by regular occurrence and abundance of thermophilous species whereas during Sarmatian, subtropical elements like Engelhardia, Reevesia, Itea, Castanopsis, Symplocaceae, Arecaceae tend to decrease and temperate elements such as Alnus, Carpinus, Betula, Corylus, Fagus have an increasing trend. A similar vegetation change is observed in the Sarmatian deposits Stăniţa-Vlădnicele borehole. During Sarmatian favourable conditions eisted in the Forecarpathian Basin for the development of mied mesophytic forest characterized by predominance of warm-temperate and subtropical elements together with many paleotropical elements. Based on the palynological assemblage we have separated following biocenosis for continental palynomophs: swamp assemblage, mied mesophytic forest, terrestrial herbs and ferns assemblage (Fig. 3).

6 Fig. 3 Main biocenosis from analyzed samples of Staniţa-Vlădnicele borehole (Diagram accomplished with Tilia graph 2.0.2)

7 Swamp assemblage. Aquatic plants like Typha indicate the presence of freshwater in the depositional environment. Swamp forest defines the lakeshore vegetation with moderate amounts of Cupressaceae and a low amount of riparian genus Sali. Mied mesophytic forest is well represented by species of fossil pollen, such as Carpinus, Quercus, Ulmus, Betula, Carya, Acer. inaceae is very abundant in the mesophytic forest. The ground cover vegetation of mied forest is made up of herbaceous plants and the presence of ferns indicate humidity (Leiotriletes, Laevigatosporites, olypodiaceoisporites a. o.). Ferns assemblage is represented by Laevigatosporites, Leiotriletes, olypodiaceoisporites, Stereisporites a. o. Herbs assemblage. This assemblage consists of seven taa mainly constituted of ground-cover vegetation in the mesophytic forest. Caryophyllaceae, and Chenopodiaceae are the dominant groups in this assemblage. Table 2. alynological assemblage identified in Stăniţa-Vlădnicele borehole. hytoplancton Deflandrea phosphoritica Eisenack 1938 (reworked) Operculodinium sp. Spiniferites sp. Spirogyra sp. Tytthodiscus sp teridophyta Cicatricosisporites sp. Echinatisporis sp. Echinatisporis wiesaënsis KRUTZSCH 1963 Laevigatosporites gracilis WILSON WEBSTER 1946 Laevigatosporites haardti (OTONIE et VE N. 1934) Th. et FLUG, 1953 subsp. haardti KRUTZSCH 1967 Laevigatosporites sp. Leiotriletes sp. Leiotriletes wolffi brevis KRUTZSCH 1962 Leiotriletes wolffi wolffi KRUTZSCH 1962 olypodiaceoisporites saonicus KRUTZSCH 1967 olypodiaceoisporites sp. Stereisporites sp. Trilobosporites weylandi Döring 1965 Triplanosporites sinuosus (FLUG. 1952) TH. FLUG 1953 Verrucatosporites cf. favus OTONIE 1931 Gymnospermatophyta Abiespollenites absolutus THIERGART 1937 Abiespollenites cedroides (THOMSON 1953) KRUTZSCH 1971

8 Abiespollenites latisaccatus (TREVISAN 1967) KRUTZSCH 1971 Abiespollenites maimus KRUTZSCH 1971 Abiespollenites sp. Cedripites lusaticus KRUTZSCH 1971 Cedripites miocaenicus KRUTZSCH 1971 Cedripites sp. Cupressacites bockwitzensis KRUTZSCH 1971 Cycadopites miocaenica NAGY 1969 Ginkgo sp. Inaperturopollenites concedipites (WODEHOUSE 1933) KRUTZSCH 1971 Inaperturopollenites hiatus (OTONIÉ 1931) THOMSON et FLUG Inaperturopollenites microforatus KRUTZSCH 1971 Inaperturopollenites sp. iceapollenites neogenicus NAGY 1969 iceapollis praemarianus KRUTZSCH 1971 iceapollis sp. inuspollenites longus NAGY 1985 inuspollenites miocaenicus NAGY ityosporites alatus (OTONIÉ 1931) THOMSON et FLUG ityosporites cedrisacciformis KRUTZSCH 1971 ityosporites insignis (NAUMOVA e BOLCHOVITINA 1953) KRUTZSCH ityosporites labdacus (OTONIÉ 1931) THOMSON et FLUG ityosporites microalatus (OTONIÉ 1931) THOMSON et FLUG 1953 ityosporites minutus (ZAKLINSKAJA 1957) KRUTZSCH 1971 ityosporites sp odocarpidites gigantea (ZAKL. 1957) NAGY 1985 odocarpidites nageiaformis (ZAKL. 1957) KRUTZSCH 1971 odocarpidites sp. Sciadopityspollenites serratus (OTONIE et VEN. 1934) THIERGART 1937 Sciadopityspollenites sp. Sciadopityspollenites varius KRUTZSCH Sequoiapollenites minor KRUTZSCH 1971 Zonalapollenites minimus KRUTZSCH + +

9 1971 Zonalapollenites rueterbergensis KRUTZSCH 1971 Zonalapollenites sp. Zonalapollenites verrucatus KRUTZSCH Angiospermatophyta. Monocotyledonatae Arecipites sp. Graminidites media (COOKSON 1947) OTONIÉ 1960 Graminidites sp. Monocolpopollenites sp. Monocolpopollenites tranquillus (OTONIÉ 1934) THOMSON et FLUG 1953 Typha angustifolia LESCHIK 1956 Angiospermatophyta. Dicotyledonatae Aceripollenites rotundus NAGY 1969 Aceripollenites sp. Alnipollenites verus (OTONIÉ 1931) OTONIÉ 1934 Betulaepollenites betuloides (FLUG 1953) NAGY Carpinipites carpinoides (FLUG 1953) NAGY 1985 Caryapollenites simple (OTONIÉ 1931) KRUTZSCH Caryapollenites sp Chenopodipollis multiple (WEYLAND et FLUG 1957) KRUTZSCH Cyrillaceaepollenites eactus (OTONIÉ 1931) OTONIÉ 1960 Cyrillaceaepollenites megaeactus (OTONIÉ 1931) OTONIÉ 1960 Engelhardtioidites microcoryphaeus (OTONIÉ 1931) THOMSON et THIERGART e OTONIÉ 1960 Ericipites ericius (OTONIÉ 1931) OTONIÉ 1960 Eucommiapollis eucommi (LANDEROVA 1990) ETRESCU 1999 Faguspollenites minor NAGY 1969 Faguspollenites sp. Ilepollenites margaritatus (OTONIÉ 1931) OTONIÉ 1960 Intratriporopollenites instructus (OTONIÉ 1931) THOMSON et FLUG 1953 Juglanspollenites maculosus (OTONIÉ 1931) NAGY 1985 Juglanspollenites sp.

10 Liquidambarpollenites sp. Magnolipollis sp. Momipites punctatus (OTONIÉ 1931) NAGY 1969 Myricipites bituitus (OTONIE 1931) NAGY latycaryapollenites sp. orocolpopollenites vestibulum (OTONIÉ 1931) THOMSON et FLUG 1953 terocaryapollenites stellatus (OTONIÉ 1931) THIERGART Quercopollenites granulatus NAGY 1969 Quercopollenites petrea NAGY 1969 Quercopollenites robur NAGY 1969 Quercopollenites sp. Saliipollenites helveticus NAGY 1969 Tricolpopollenites liblarensis (THOMSON 1950) THOMSON et FLUG 1953 subsp. Liblarensis Tricolporopollenites cingulum (OTONIE 1931) THOMSON et FLUG 1953 subsp. pusillus (OTONIE 1934) THOMSON et FLUG 1953 Tricolporopollenites henrici (OTONIÉ 1931) KRUTZSCH 1960 Tricolporopollenites marcodurensis FLUG et THOMSON 1953 Tricolporopollenites microhenrici (OTONIÉ 19) KRUTZSCH 1960 Tricolporopollenites sp Ulmipollenites undulosus WOLFF 1934 Zelkovaepollenites potoniéi NAGY Zelkovaepollenites sp Zelkovaepollenites thiergarti NAGY Gombaspora (Hyphomycetes)(Fung) Legend: low frequency + high frequency Conclusions Micropaleontological assemblage identified in the analyzed samples from Stăniţa-Vlădnicele borehole is assigned to Badenian (sample 310 from 975 m) and to Sarmatian (samples 1-9 from 140 to 975 m), been possible even an distribution on stages. The assemblage determined from sample 9 (950 m) can be attributed to Buglovian, samples 5-8 (from m) are assigned to Volhynian and samples 1-4 (from m) are attributed to Bessarabian. Regarding palynological assemblage, subtropical elements like Engelhardia, Reevesia, Itea, Castanopsis, Symplocaceae, Arecaceae tend to decrease and temperate elements such as Alnus, Carpinus, Betula, Corylus, Fagus have an increasing trend. During Sarmatian favourable conditions eisted in the Forecarpathian Basin for the development of mied mesophytic forests characterized by predominance of warm-temperate and subtropical elements together with many paleotropical elements. Based on the palynological assemblage we have separated following biocenosis for continental

11 palynomophs: swamp assemblage, mied mesophytic forest, terrestrial herbs and ferns assemblage. Dinoflagelate assemblage is represented by Operculodinium, Spiniferites, Spirogyra and few reworked species of hytoplankton with higher percentage and diversity is present in sample 3, from 485 m. Acknowledgements This work has been supported by Romanian Ministry of Education, Research and Innovation under a N-II-IDEI No. 975/2008 research grant, directed by prof. dr. Mihai Brânzilă. Gabriel Chirilă wants to thank to dr. Daniel Tabara to given help in the preparation and determination of palynomorphs. References Brânzilă M., 1999, Geologia părţii sudice a Câmpiei Moldovei. Ed. Corson, Iaşi. Brânzilă M., Ţabără D., 2005, The palynological content of Lower Basarabian (The clays with Cryptomactra) on the Moldavian latform. Anal. Şt. Univ. Al. I. Cuza Iaşi, geol., T. XLIX L ( ), , Iaşi. Brânzilă M., 2005, Foraminifera assemblages of the backbulge depozone from the Moldavian latform - the Basarabian -, Acta alaeontologica Romaniae, vol. IV, Iaşi, Chirilă G., 2008, Studiul paleofloristic al Sarmaţianului din bazinul Văii Râşca. Teză de doctorat, Universitatea Al. I. Cuza Iaşi. Chirilă G., Ţabără D., 2008, alaeofloristic study of the Volhynian from Râşca (Moldavian latform) - alaeoclimatic and palaeoenvironment implications. Acta alaeontologica Romaniae, vol. VI, Iaşi, Grasu C., Brânzilă M., Miclăuş C., Boboş I., 2002, Sarmaţianul din sistemul bazinelor de foreland ale Carpaţilor Orientali. Ed. Tehnică, Bucureşti, p Ionesi L., 1994, Geologia unităţilor de platformă şi a Orogenului Nord - Dobrogean, Ed. Tehnică, Bucureşti. Ionesi L., Ionesi B., Lungu A., Roşca V., Ionesi V., 2005, Sarmaţianul mediu şi superior de pe latforma Moldovenească. Editura Academiei Române, p Ivanov D., Ashraf R. Mosbrugger V., alamarev E. 2002, alynological evidence for Miocene climate change in the Forecarpathian Basin (central aratethys,nwbulgaria), alaeogeogr. alaeoclimatol. alaeoecol. 178 (2002) Ivanov D., Ashraf A., Mosbrugger V., 2007, Late Oligocene and Miocene climate and vegetation in the Eastern aratethys area (northeast Bulgaria), based on pollen data. alaeogeography, alaeoclimatology, alaeoecology 255 (2007) Marret F., Zonneveld K. A. F. 2003, Atlas of modern organic-walled dinoflagellate cyst distribution. Review of alaeobotany and alynology, V Mosbrugger, V., Utescher, T., The coeistence approach - a method for quantitative reconstructions of Tertiary terrestrial palaeoclimate data using plant fossils. alaeogeography, alaeoclimatology, alaeoecology, 134, opescu Gh., 1995, Contributions to the knowledge of the Sarmatian foraminifera of Romania. Romanian Jornal of alaeontology, 76, Ţabără D., 2008, alinologia Sarmaţianului mediu şi superior din latforma Moldovenească. Editura Universităţii Al. I. Cuza Iaşi, 319 p., 23 pl. Ţabără D., Chirilă G., araschiv V. 2009, The Sarmatian macro- and microflora from Stan s Hill Bozieni (Moldavian latform). Analele Stiintifice ale Universitatii Al. I. Cuza Iasi, Geologie. Tomul LV, Nr. 2, 2009, pag Wall D., Dale B., Lohman G.., Smith W.K., 1977, The environmental and climatic distribution of dinoflagellate cysts in the North and South Atlantic Oceans and adjacent seas. Mar. Micropaleontol. 2,

12 lates caption late I 1-3. Melonis pompilioides (Ficht. et Moll). 1. Side view 315; 2. Detail view of fig ; 3. Edge view ullenia bulloides (d Orb). Edge view Sphaeroidina austriaca d Orb Cibicides pachiderma (Rzehak). Side view Cibicides dutemplei (d Orb). Side view Ammonia beccarii (Linne). Side view 440 late II 1, 2. Cibicides badenensis (d Orb). (1. Side view 600; 2. Edge view 560;) 3. Cibicides lobatulus (Walker & Jacob). Side view Quinqueloculina karerri Reuss. (4. Apertural view 760; 5. side view 400; 6. Detail of fig 5 10) 7. Articulina problema Bogd. Side view Elphidium minutum (Reuss). Side view Elphidium macellum Fichel et Moll. Side view Elphidium crispus (Linne). Side view 0. late III 1-6. orosononion subgranosus (Egger). 1, 3, 4, 5 Side view (fig 1 650, fig , fig , fig ); 6. Detail of fig 4. X1000; 2. Edge view 400) 7. Elphidium aculeatum d'orbigny. Side view Elphidium regina caucasica Bogd. Side view Elphidium regina regina (Linne). Side view orosononion martkobi (Bogd). Side view 200. late IV 1.Tytthodiscus sp. 2.Zonalapollenites verrucatus KRUTZSCH Zonalapollenites neogenicus KRUTZSCH Abiespollenites latisaccatus (TREVISAN 1967) KRUTZSCH ityosporites labdacus (OTONIÉ 1931) THOMSON et FLUG 1953 late V 1.Quercopollenites robur NAGY Quercopollenites petrea NAGY , 5-8. Quercopollenites sp. 4. Quercopollenites robur NAGY ityosporites macroinsignis KRUTZSCH ityosporites pristinipollinius (TRAV. 1955) KRUTZSCH ityosporites insignis (NAUMOVA e BOLCHOVITINA 1953) KRUTZSCH ityosporites labdacus (OTONIÉ 1931) THOMSON et FLUG odocarpidites gigantea (ZAKL. 1957) NAGY odocarpidites piniverrucatus KRUTZSCH 1971

13

14

15

16

17