ISSN 00310301, Paleontological Journal, 2010, Vol. 44, No. 10, pp. 1321–1331. © Pleiades Publishing, Ltd., 2010 Paleogene Coalforming Plants of the Zeya–Bureya Basin (Amur River Region) V. S. Markevicha, E. V. Bugdaevaa, D. J. Nicholsb, and Ge Sunc aInstitute of Biology and Soil Science, Far East Branch, Russian Academy of Sciences, pr. Stoletiya Vladivostoka 159, Vladivostok, 690022 Russia email: [email protected] bDenver Museum of Nature and Science, 2001, Colorado Boulevard, Denver, CO 802055798 USA cJilin University, Shenyang Normal University, 253, North Huanghe Street, Shenyang, 110034 China email: [email protected] Received April 14, 2009 Abstract—Coalforming plants from the Early Paleogene coal mines of the Zeya–Bureya Basin (Amur River Region) were studied. Dispersed cuticles of taxodialeans were obtained from coals for the first time in this region. Since the Danian, taxodialeans became dominant elements in peatforming environments and pro vided abundant plant material that transformed into coal. Key words: Paleogene, Zeya–Bureya Basin, coalforming plants, taxodialeans. DOI: 10.1134/S0031030110100084 INTRODUCTION phytomass became mortmass which in turn was trans formed into the brown Amur coals. Upper Cretaceous and Cenozoic deposits are widespread in the Zeya–Bureya Basin. Our data show that the basin started to fill with sediments in the San MATERIAL AND METHODS tonian. At the base of the stratigraphic sequence, there Many elements of the coalforming plant commu is the Kundur Formation (Santonian to Campanian), nity can still be identified in the coal. At the time of the which correlates with the Yongancun and Taipinglin mire formation and growth, climatic conditions were chang formations on the right bank of the Amur River such that very little sediment was being transported (Markevich et al., 2005b, 2005c). The Tsagayan For mation (Maastrichtian to Danian) conformably over lies the Kundur Formation. On the right bank, the r Yuliangzi, Furao, and Wuyun formations occupy the e Blagoveshchensk iv same stratigraphic position as the Tsagayan Formation R a y (Regional Geology …, 1993; Flora and Dinosaurs …, re 2001; Akhmetiev et al., 2002; Markevich et al., 2004; Am u ur B (H Raichikhinsk Sun et al., 2004; Kezina, 2005a, 2005b). eil Russia on gjia 2 Longterm studies of the Cretaceous and Early ng ) R Paleogene palynostratigraphy of the Zeya–Bureya ive Arkhara Basin have provided taxonomically rich palynofloras; r palynological assemblages of different ages, with char 1 acteristic species, have been recognized; wide interre gional correlation was performed to date particular 3 strata (Markevich, 1994; Flora and Dinosaurs …, 2001; Jiyain Markevich et al., 2004, 2005a). The Arkhara– China Boguchan, Raichikhinsk, and Wuyun brown coal mines are located in the southeastern part of the Zeya–Bureya Basin (Fig. 1). Our study dated these 0 50 100 km coals to the Early Paleocene, most likely, Late Danian (Markevich et al., 2004, 2005a; Markevich and Fig. 1. Distribution of brown coal mines in the southeast Bugdaeva, 2008). At that time, environmental condi ern Zeya–Bureya Basin: (1) Arkhara–Boguchan; tions favored the formation of extensive mires. The (2) “Pioneer” section of Raichikhinsk; and (3) Wuyun. 1321 1322 MARKEVICH et al. into the basin allowing biogenic sedimentation, with (less than 1 m), and “Velikan” (about 10 m). In the almost complete absence of clastic sediments. There section studied, the uppermost coal seam is absent fore, it is possible to assume that plants that gave rise to (Fig. 2). the coal deposits were autochthonous and provided The palynospectrum (sample 01) from a thin the first elements of peat accumulation. Since the (about 25 cm thick) clay bed approximately in the clastic deposits represent the material transported middle of the “Nizhnii” seam is dominated by fern from the source area, phytofossil assemblages from the spores, mostly Cyathidites Couper and Laevi terrigenous deposits between the coal layers are often gatosporites Ibrahim. Gymnosperm pollen is repre mixed, consisting of elements from both the slope and sented by abundant Pinaceae and Taxodiaceae. lowland communities. Angiosperms are rare, dominated by Aquilapollenites Sections of the Wuyun Coal Mine on the right bank Rouse (Fig. 3). of the Amur River were sampled and described in 2002 In the palynospectrum from the lower coal seam and 2008; the Arkhara–Boguchan and Raichikhinsk (samples 02, 03), the number of fern spores and pollen (section “Pioneer”) coal mines, in August 2003. This of Taxodiaceae, Cupressaceae, and Taxaceae (TCT) work was done within the framework of the Interna are reduced. The relative abundance of the Pinaceae tional Project “Cretaceous Biota and the K–T increases, so that it predominates. Angiosperms are Boundary of Heilongjiang (Amur) River Area” under rare, as before; the proportion of plants producing direction of Prof. Sun Ge (Jilin University and Shen “unica"type pollen, sharply irreversibly declines. yang Normal University, Chinese Peoples’ Republic). Gymnosperm pollen, mostly TCT and Pinaceae, pre The following materials were used in this study: vails in the palynospectrum from the clay of the lower Arkhara–Boguchan Coal Mine, 29 samples (collec plantbearing bed (samples 04–07, 09–11, 13–15). tion No. AB1153); Raichikhinsk Coal Mine (section Spores of Laevigatosporites are abundant. The diversity “Pioneer”), 9 samples (collection No. P1107); and of angiosperms increases with the appearance of Tria Wuyun Coal Mine, 7 samples (collection No. W1076). triopollenites Pflug. Taxonomic diversity of the palyno Dispersed cuticles were separated from coals of the spectrum from a paleosoil (sample 17) is very low. Pol Wuyun mine (Pl. 30). All collections are stored in the len of the Pinaceae and Taxodiaceae is abundant. Institute of Biology and Soil Science of the Far East Angiosperms are absent. Branch of the Russian Academy of Sciences, Vladi The proportion of Laevigatosporites in the palyno vostok (IBSS). Samples for the spore–pollen analysis spectrum from the lower coal interlayer of the “Dvoi were processed using the standard maceration method noi” seam (samples 19, 20) sharply increases (57.8%), proposed by Lüber and Waltz for highly metamor the proportions of all other main groups decrease. The phosed rocks and coals (“Paleopalynology,” 1966). To palynospectrum from the siltstone layer (samples 21, obtain cuticles, the coals were oxidized by concen 22) is similar in taxonomic composition to that from trated nitric acid, washed with distilled water, then, the previous layer. Laevigatosporites predominates treated with 10% alkali (KOH) and rinsed. (69%), the proportions of all other plant groups are The cuticular membranes were mounted on per insignificant. manent slides for observation under a light microscope In sample 25 from the upper coal interlayer of (LM) or were placed on standard stubs, splutter coater “Dvoinoi” seam, the proportions of the ferns Cyathid with gold and imaged using a scanning electron micro ites and Laevigatosporites (18%) and Pinaceae (19%) scope (SEM). Photographs were produced by are almost equal. The proportion of flowering plants, L.F. Simanenko, using a Zeiss Axioplan 2 imaging light particularly those producing porate pollen, increases microscope (FEGI FEB RAS), by N.N. Naryshkina, to 17%. using a Zeiss EVO40 scanning electron microscope, In samples 26–29 from the plantbearing clay, the and authors, using a Zeiss Axioscop 40 with camera proportions of taxodialeans and angiosperms with Axiocam HRc light microscope (IBSS FEB RAS). porate pollen increase considerably (33 and 21%, respectively). Sample 30 collected from sandstone is similar in Arkhara–Boguchan Coal Mine the proportions of taxodialeans and angiosperms with This mine produces coal from four productive porate pollen (27%) to the sample just below it from seams (upward in the section): “Nizhnii” (about 2 m clay. The two groups are dominants in the palynospec thick), “Dvoinoi” (about 8 m), “Promezhutochnyi” trum from sandstone. Explanation of Plate 30 Figs. 1–8. Dispersed cuticle of Taxodium sp., sample no. WII146,2, coals of the Wuyun Coal Mine in the Zeya–Bureya Basin, Amur River Region, Wuyun Formation: (1) stomatal band, internal view; (2) two stomatal and nonstomatal bands, external view; (3) distribution of stomata in the band, internal view; (4) concentric arrangement of the stomata around cutinized cell, external view; (5, 6) stoma, internal view; (7) stomatal band, with stomata oriented transversely relative to veins, external view; (8) sto matal and nonstomatal bands. Scale bar in (1, 4, 7) 20 µm, (2, 3, 8) 100 µm, (5, 6) 10 µm. (1–7) SEM, (8) LM. PALEONTOLOGICAL JOURNAL Vol. 44 No. 10 2010 PALEOGENE COALFORMING PLANTS OF THE ZEYA–BUREYA BASIN 1323 Plate 30 1 2 4 3 5 6 7 PALEONTOLOGICAL JOURNAL Vol. 44 No. 10 2010 1324 MARKEVICH et al. 128° 130° r e v ArkharaBoguchan i R Russia a y e r e f Z Blagoveshchensk v i i s R s a a y e M r u a 50° 50° B y A Pioneer re mur u (H B 25 m eilo ngj iang) Ri A ver r kh ar a B China og uch Wuyun an M aly Khin gan Ridge 20 m Wuyun Pioneer 15 m 10 m 123456789 Fig. 2. Geological sections of the Arkhara–Boguchan, Wuyun, and “Pioneer” brown coal mines. Inset is a schematic paleogeo graphic map of the time of coal formation in the Zeya–Bureya Basin, where white color shows the valley, gray is mountainsides framing the valleys, black is swamp lowlands; designations: (1) conglomerate, (2) sandstone, (3) siltstone; (4) clay, (5) coal, (6)rhyolite tuff; (7) paleosoil; (8) crossbedding structures; (9) points of sampling. PALEONTOLOGICAL JOURNAL Vol. 44 No. 10 2010 PALEOGENE COALFORMING PLANTS OF THE ZEYA–BUREYA BASIN 1325 Trilete Triporate Monolete spores Bisaccate pollen TCT pollen Others spores pollen pollen Number of sample Tricolpate 36 34 31–33 30 26–29 25 21–22 19–20 17 04–15 02–03 01 %0 10 20 10 20 30 40 50 60 10 20 30 40 50 60 10 20 30 10 10 20 10 Fig.