首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 593 毫秒
1.
全球石炭纪-二叠纪植物群的演化和分布特征   总被引：8，自引：0，他引：8  
在全球范围内，石炭纪和二叠纪植物群可以划分为五个植物群，即早石炭世（杜内期、维宪期和纳缪尔Ａ期）的全球性拟鳞木植物群（Ｌｅｐｉｄｏｄｅｎｄｒｏｐｓｉｓｆｌｏｒａ）和晚石炭世（纳缪尔Ｂ—Ｃ期、威斯发期和斯蒂芬期）至二叠纪的华夏植物群、欧美植物群、安加拉植物群和冈瓦纳植物群。早石炭世拟鳞木植物群广泛分布于世界许多地区，具有全球一致性，以Ｌｅｐｉｄｏｄｅｎｄｒｏｐｓｉｓ，Ｓｕｂ ｌｅｐｉｄｏｄｅｎｄｒｏｎ，Ａｒｃｈａｅｏｓｉｇｉｌａｒｉａ，Ａｒｃｈａｅｏｃａｌａｍｉｔｅｓ，Ｃａｒｄｉｏｐｔｅｒｉｄｉｕｍ，Ｒｈｏｄｅｏｐｔｅｒｉｄｉｕｍ，Ｒｈａ ｃｏｐｔｅｒｉｓ，Ａｄｉａｎｔｉｔｅｓ，Ｔｒｉｐｈｙｌｏｐｔｅｒｉｓ等为特征。拟鳞木植物群逐渐从泥盆纪植物群分离出来，繁盛于早石炭世早期，绝灭于早石炭世末期。在早石炭世和晚石炭世的转换期，全球性气候变化和构造运动导致早石炭世拟鳞木植物群典型分子的绝灭和晚石炭世植物群先驱分子的出现。因此，华夏植物群、欧美植物群、安加拉植物群和冈瓦纳植物群衍生于早石炭世全球一致性拟鳞木植物群，但它们各自发展在不同的环境中。  相似文献   

2.
华夏植物群及其与全球同期植物群的比较   总被引：9，自引：0，他引：9  
孙克勤 《地学前缘》2002,9(3):73-84
文中研究的焦点是华夏植物群及其与全球同期植物群的比较 ,并论证了石炭纪和二叠纪的古植物地理再造。在石炭纪和二叠纪 ,华夏植物区和欧美植物区皆位于具热带气候的赤道区 ,在类似的气候条件下 ,这两个地区的一些植物具有形态上的相似性。此外 ,华夏植物群含有一些与欧美植物群共有的分子 ;因此 ,这两个植物群的关系比较密切。尽管华夏植物群具有相当数量的分子是与欧美植物群所共有的 ,但是在大羽羊齿类植物中 ,在种级上两者并没有相同的成分。华夏植物群是以热带雨林气候为特征。在二叠纪 ,华夏区的气候比欧美区的气候更为湿润。华夏植物群的分子不同于安加拉植物群的分子 ;此外 ,安加拉植物群代表了温带气候条件。在石炭纪和二叠纪 ,冈瓦纳植物群分布在南半球高纬度地区 ,不同于分布于北半球低纬度的华夏植物群的组成分子 ;因此 ,这两个植物群没有必然联系。在石炭纪和二叠纪 ,在北半球华夏植物群与欧美植物群的一些植物在形态上的相似性以及在南半球 (西藏、沙特阿拉伯、土耳其、新几内亚和伊拉克 )一些华夏型分子的分布可以是起因于类似的气候条件、大陆位置、板块运动、洋流作用、古地理环境等因素的影响。华夏植物群与其同期植物群的差异反映了植物群成分、古气候、古地理位置和陆地生态系在时?  相似文献   

3.
《Earth》2008,86(3-4):85-116
Wetland plant communities persisted though much of the Pennsylvanian in Euramerica and are the dominant coal forming vegetation in this region. Distribution of these floras show a dramatic decline at the end of the Carboniferous with many of the plant genera and species becoming extinct by the onset of the Permian. This has been correlated with climate change and in particular aridification associated with northwards plate motion and Euramerica moving into the doldrums, but is also associated with the Variscan orogeny and forefront destroying large areas of formerly lowland basinal settings. Other factors may include Pennsylvanian glaciations as evidenced by cyclothem and rhythmical deposition in lowlying wetland settings, and change in eustatic base level. Evidence from Euramerica demonstrates extinction of this kind of wetland biota by the earliest Permian and the development of drier floras including conifer dominated assemblages. However, new data from other parts of the world, most notably North China, confirm this model and highlight the presence of similar coal swamps ranging from the Late Pennsylvanian through the Permian. In this paper we summarise and synthesize recent taxonomic and systematic investigations undertaken on the plant fossils from the Pennsylvanian Benxi Formation – the oldest recognised wetland plant community in China – and the Early Permian Taiyuan Formation – the best preserved wetland plant community from China. Results indicate a remarkable similarity of the Pennsylvanian–Early Permian floras of North China with the older assemblages in the Pennsylvanian of Euramerica, and the presence of typical ‘Euramerican’ coal swamp plant families, genera and in some cases species in China. Conclusions include the presence of the Ameriosinian phytogeographical realm uniting Euramerica and northern Cathaysia at this time, coal swamps in the Permian of North China evolving from a ‘Euramerican’ origin, and the dramatic floral turnover at the end of the Carboniferous representing a regional event rather than a global extinction episode. Patterns of plant distribution through this interval have profound implications on established palaeogeographical models and support continental connection between Euramerica and Cathaysia before the end of the Carboniferous, contradicting ideas of Cathaysian island biogeography and biotic distinction. Continental connection appears to be related to glacial eustatic low-stand and previously shallow marine environments becoming vegetated. Also important is the fact that in both Euramerica and North China the pattern of floristic demise within wetland plant communities are similar to each other, implying the same causal mechanisms, with plants occupying waterlogged positions being the most severely devastated. However, ecosystem demise occurred at the end of the Carboniferous in Euramerica and in the middle Permian in North China, but in both cases the primary cause was climate change.  相似文献   

4.
Roof shale floras help understand the transition of vegetational landscapes from a peat–forming environment to a clastic one, but are seldom investigated in the Cathaysian province(typical present day China and East Asia). Here the roof shale flora of Coal Seam 6 from the lower Permian Taiyuan Formation of the Wuda Coalfield, Inner Mongolia, is systematically described and its ecostratigraphic and phytogeographic implications are discussed. The flora is composed of seven plant groups, including Lepidodendrales, Medullosales, Gigantopteridales, Peltaspermales, Noeggerathiales, Cordaitales and Cycadales. Many of these taxa are also documented in Euramerica, and the floral composition indicates a more intimate relationship between Cathaysia and Euramerica during the Cisuralian than previously thought. However, there are few genera and species in common with those of the underlying peat–forming flora. Moreover, the flora is hardly comparable with the commonly known flora of the Taiyuan Formation. Such assemblage differences are very likely due to changes of taphonomic and environmental phases, rather than evolutionary floral succession. For a full and more precise understanding of the floral composition, succession and the floristic discrepancy in different depositional environments, an ecostratigraphic investigation on the Late Palaeozoic of Cathaysia is advocated.  相似文献   

5.
The town of Colne in Pennine east Lancashire, northern England—once a centre of the textiles trade—is now best known locally as the home of Boundary Mill ‘shopping experience’. But there is more to the town than meets the eye, including three significant geologists.  相似文献   

6.
A new genus and species, Rebouliothallus huolinhensis sp. nov., and two uncertain species, Ricciopsis sp. and Hepaticites sp., are described. The fossils were collected from the Lower Cretaceous Huolinhe Formation of Huolinhe Basin, northeastern China. The new genus Rebouliothallus was established in the Aytoniaceae family of Marchantiales. Rebouliothallus huolinhensis appears to be quite similar to species of the extant genus Reboulia Raddi. The species is characterized by the relatively large ventral scales. Ventral scales are large, imbricate and arranged in two rows on the ventral surface. Rhizoids are either pegged or smooth. Ricciopsis sp. is characterized by the rosette-forming thallus. Hepaticites sp. shows some similarities to liverworts. Of the forty-nine Early Cretaceous floras of China, only two floras, one from the Huolinhe basin, Inner Mongolia and the other from the Jixi Basin, Heilongjiang Province, contain fossil liverworts. The rare fossil liverwort records in the Early Cretaceous floras of China may be the result of taphonomic bias.  相似文献   

7.
Fossil plant compressions and impressions are abundantly associated with coals of Mississippian and Pennsylvanian age in the central Appalachians, Illinois Basin, and elsewhere in the United States. Remains of the aerial plant parts occur most commonly in shale directly overlying coal, especially in the vicinity of contemporaneous paleochannels. Most roots and a few stumps are found preserved in situ; however, most aerial plant fossils were transported prior to burial. There is good evidence that fossil plants preserved in roof shales are mostly the same types of plants from which the coal formed. Mississippian coal floras are lower in diversity than later ones. Quantitatively important plants include only 2 lycopod genera, 1 arthrophyte genus, 1 fern genus, and 5 seed fern genera. Pennsylvanian floras, on the other hand, include abundant representatives of 5 lycopod genera, 2 arthrophyte genera, 4 fern genera, 5 seed fern genera, and 1 coniferophytic genus. The swamp floras were never in equilibrium, though change appears to have been particulary rapid near the boundary between the Mississippian and the Pennsylvanian.  相似文献   

8.
The Upper Carboniferous, coal-bearing sequence of the Intrasudetic Basin (SW Poland) includes coals ranging from high-volatile bituminous to anthracitic rank. The lowest values of reflectance are recorded around the basin margins (0.6% R0 max), the highest ones appear in the center of the basin (exceeding 4% R0 max). Reflectance gradients are very high, reaching 0.6%/100 m in the centre of the basin.A comparison of the isoreflectance maps for three lithostratigraphical units—the Walbrzych, Bialy Kamien and Zacler Formations, with the present-day burial depth and the depth of burial during the Westphalian B/C—indicates that there is a strong relationship between reflectance and the sediment cover during the Westphalian B/C, particularly in the vicinity of Walbrzych and Lubawka. This suggests that the increase in coal rank is related to the increase in cover which permitted the temperature to build-up to high values.In the eastern and central parts of the basin and the Nowa Ruda area, higher reflectance than that derived from burial depth is observed which is believed to result from higher heat flow from the basement. The volcanic rocks of the Intrasudetic Basin appear to have little effect on coal rank and are not considered to be a significant contributor to the heat flow of the region.During coalification, the oldest Westphalian coal seams were buried to about 700 m and the youngest seams of the Walbrzych Formation to 900 m. Around the basin margins the coals had reached their present-day rank by the Westphalian B/C and in the central part probably by the end of the Stephanian. Most effective coalification took place during the Westphalian A,B occupying a period of less than 20 million years. The coalification temperature is calculated to be 160–170°C with a geothermal gradient of 8–10°C/100 m. These geothermal conditions support the suggestion of a volcanic origin for the Intrasudetic Basin.  相似文献   

9.
We describe a calcareously permineralised fossil tree-trunk, preserved as driftwood, within hemipelagic sediments of the Cretaceous Puez Formation near Wolkenstein, South Tyrol, Italy. Planktic foraminiferal assemblages recovered from the marls containing the fossil wood indicate a latest middle Albian age. Based on its wood anatomy, the trunk is assigned to Agathoxylon and probably has an affinity with the conifer family Araucariaceae. The wood lacks pronounced tree-rings consistent with tree growth within the broad humid tropical belt that existed at that time. The trunk contains cylindrical chambers filled within faecal pellets, demonstrating that oribatid mites infested the tree, either during life, or shortly after death. Prior to final burial, the tree-trunk drifted out into the open sea for a considerable period as indicated by extensive borings assigned to the ichnospecies Teredolites longissimus and produced by teredinid bivalves. Relatively little is known about the Cretaceous floras of Italy, so this new finding fills a gap in our knowledge of the composition and ecology of the vegetation of this region.  相似文献   

10.
Strata of Westphalian D age on the western coast of the Sydney Basin expose a fossil forest of approximately 30 lepidodendrid trees within one of several clastic splits of the Harbour Seam. A multidisciplinary approach was employed to interpret the origins of the coat bed, the depositional history of the site and the response of the fossil forest to changing edaphic conditions. The megaspore and miospore records indicate that the mire vegetation was dominated by arboreous lycopsids, especially Paralycopodites, with subdominant tree ferns. Petrographic, palynological and geochemical evidence suggest that the Harbour coal bed at Table Head originated as a rheotrophic (cf. planar) mire (eutric histosol). The mire forest is interpreted to have been engulfed by prograding distributary-channel sediments; sparse protist assemblages are suggestive of a freshwater delta-plain lake environment occasionally in contact with brackish waters. Lepidodendrids persisted as site colonizers of clastic substrates even after burial of the rheotrophic peatland and influenced the morphology of deposited sediment, but apparently were unable to colonize distributary channels. Equivocal taxonomic data (compression fossils) show the fossil forest to have been composed of both monocarpic (Lepidodendron) and polycarpic (Diaphorodendron, Paralycopodites, ?Sigillaria) lycopsids, genera recorded in the palynology of the uppermost ply of the underlying coal bed. Comparatively rare within the clastic beds of the fossil forest, however, is the stem compression of Paralycopodites, whose dispersed megapores and miospores dominate the underlying coal bed. Tree diameter data recorded equivalent to breast height indicate a forest of mixed age. These data would appear to suggest that some lepidodendrids employing a polycarpic reproductive strategy were better able to cross the ecological barrier imposed between peat and clastic substrates. Foliar compressions indicate that an understory or stand of Psaronius type tree ferns co-existed with the lepidodendrids on clastic substrates, which developed as incipient gleysol soils. The entombment of the forest can be ascribed to its distributary coastal setting, local subsidence and a seasonal climate that fostered wildfire and increased sedimentation.  相似文献   

11.
The sulphur content of coal is an important consideration when developing reserves for exploitation, driven by emission limits from power stations becoming more stringent. Variations in the sulphur content of Westphalian A and B coals from the predominantly freshwater Northumberland Coalfield, Northeast England, were studied according to their regional, stratigraphic and in-seam location. The observed variation in sulphur content spatially increases towards the source area away from more marine influenced areas, with increased sulphur content through time linked to changes in the general depositional environment as conditions became more marine-influenced. A model of basinal surface water and groundwater flow driven by post-depositional source area tectonism is thought to have played only a minor role in contributing secondary sulphur to the coal. However, the isotopic composition of coal pyrite shows a similar range in composition to that of pyrite and other sulphides from the North Pennine Orefield along the southern margin of the coalfield, suggesting an additional potential source of secondary sulphur, as sulphur-rich fluids were expelled northwards through the coal measures during early Permian Variscan transpression from the south. The Westphalian A and B are interpreted as third-order depositional sequences, defined by third-order maximum flooding surfaces. Each sequence is made up of several coal-bearing fourth-order parasequences, which tend to be more brackish to marine in character, on either side of the third-order maximum flooding surfaces when base level was relatively high. The lowest sulphur coals are confined to the lower to middle, relative low stand part of the Westphalian A third-order base level curve and the lowest part of the Westphalian B third-order base level curve. This difference is attributed to a more rapid rise of base level in the Westphalian B. The stratigraphic and spatial distribution of coal sulphur has been used as a guide to prediction of reserve identification for surface mining operations.  相似文献   

12.
The delivery of volcanogenic sulphur into the upper atmosphere by explosive eruptions is known to cause significant temporary climate cooling. Therefore, phreatomagmatic and phreatoplinian eruptions occurring during the final rifting stages of active flood basalt provinces provide a potent mechanism for triggering climate change.

During the early Eocene, the northeast Atlantic margin was subjected to repeated ashfall for 0.5 m.y. This was the result of extensive phreatomagmatic activity along 3000 km of the opening northeast Atlantic rift. These widespread, predominantly basaltic ashes are now preserved in marine sediments of the Balder Formation and its equivalents, and occur over an area extending from the Faroe Islands to Denmark and southern England. These ash-bearing sediments also contain pollen and spore floras derived from low diversity forests that grew in cooler, drier climates than were experienced either before or after these highly explosive eruptions. In addition, coeval plant macrofossil evidence from the Bighorn Basin, Wyoming, USA, also shows a comparable pattern of vegetation change. The coincidence of the ashes and cooler climate pollen and spore floras in northwest Europe identifies volcanism as the primary cause of climate cooling. Estimates show that whilst relatively few phreatomagmatic eruptive centres along the 3000 km opening rift system could readily generate 0.5–1 °C cooling, on an annual basis, only persistent or repeated volcanic phases would have been able to achieve the long-term cooling effect observed in the floral record. We propose that the cumulative effect of repeated Balder Formation eruptions initiated a biodiversity crisis in the northeast Atlantic margin forests. Only the decline of this persistent volcanic activity, and the subsequent climatic warming at the start of the Eocene Thermal Maximum allowed the growth of subtropical forests to develop across the region.  相似文献   


13.
This study presents the first report of mesofossils of flowers, fruits and seeds found in the Cretaceous of New Zealand. The specimens were recovered from the Late Cretaceous (Maastrichtian, ca. 70 Ma) at Kai Point Mine, South Island in a sequence of floodplain sediments sampled just below the Barclay Coal Seam. Angiosperm flowers, fruits and seeds occur in the sample. The most common form is an actinomorphic flower with two whorls of three tepals. Anther bases are preserved and the ovary develops into a drupe, all features that are consistent with placement in the Lauraceae. Reproductive structures including seeds of conifers are also described, with some allied to the Podocarpaceae. This contrasts with interpretations of the flora based on macrofossils that indicate abundant Araucariaceae and highlights the different perspectives that mesofossil floras give to any assemblage. The results of the present study support a Late Cretaceous flora at this site mainly dominated by conifers with affinities to Podocarpaceae but also including lauraceous angiosperms.  相似文献   

14.
ABSTRACT
The Westphalian B sediments of NE England were deposited on part of a coastal plain with subdued relief. Most of the fine-grained sediments were deposited by small fluvially dominated muddy deltas which fed into shallow freshwater lakes in tectonic depressions a few metres deep and a few tens of kilometres across.
Coalfield lakes contained an abundant low-diversity bivalve fauna and existed for thousands of years before delta infill. Pro-delta clay rhythmites, formed by flood turbidites, coarsened up into wide silty mouth bars, which merged up into channel mouth sands, inversely-graded subaqueous levee deposits and sandy channel fills. Delta complexes were either abandoned below water level leaving a lake, or were colonized by plants, which resulted in trapping of suspended sediment and build-up of a seatearth to near water level when peats could accumulate. These swamps were analogous to the present raised bogs of Indonesia and had a lateral zonation of vegetation to a central low-diversity flora. Upwards reversal of this zonation and the succession of coals by lake sediments show that peat floras were killed by drowning due to rapid tectonic subsidence. Subsurface data show that seam splits and sand-body locations were tectonically controlled, and that the lake deltas in this area were distant from any major sand distributary.  相似文献   

15.
丁秋红 《吉林地质》1993,12(4):32-41
本文在系统研究吉中地区晚期中生代植物群的基础上,论述了沙河子组和大羊革沟组植物群的演替,分析了化石植物群的保存特点及其沉积环境。应用现代植物生态学的原理和方法,依据现实主义类比原则,分析了植物群的古气候意义,认为本区晚中生代由温暖、潮温的温带型气候转变为温热、湿润的暖温带型气候条件。根据植物群的组成和性质特征,认为本区晚中生代植物地理区应属瓦赫拉梅耶夫(1988)划分的西伯利亚—加拿大植物地理区范畴。  相似文献   

16.
The Westphalian C and D fluvial sandstones in the Campine Basin (north‐east Belgium) are potential reservoirs for the sequestration of CO2 and interesting analogues of the hydrocarbon reservoirs in the Southern North Sea. Although these sandstones were deposited in a relatively short period of time, their reservoir properties and mineralogical compositions are very different. A petrographic study complemented with stable isotope analyses, fluid inclusion microthermometry and X‐ray diffraction analyses of the clay fractions of the sandstones, which were sampled from deep boreholes (>1000 m) in the Campine Basin, revealed that these differences are related mainly to the climate at the time of deposition. The most important eogenetic processes affecting the Westphalian sandstones were the generation of a pseudomatrix by physical compaction of Al‐silicates and lithic fragments that were strongly altered by extensive meteoric leaching, kaolinitization of unstable silicates and precipitation of siderite. These processes had a detrimental influence on the reservoir properties of Westphalian C sandstones, but their impact on the Westphalian D sandstones was minimal. The difference is assumed to be related to the climate at the time of deposition, which changed from tropical humid in the Westphalian C to semi‐arid/arid during the Late Westphalian D. Both the Westphalian C and D sandstones were affected by similar mesogenetic processes. Mesogenetic quartz cementation resulted from chemical compaction and illitization of kaolinite, K‐feldspar and smectitic clays. Illitization of kaolinite was controlled by the available quantities of co‐existing kaolinite and K‐feldspar and mainly affected the Westphalian D sandstones. Illitization of K‐feldspar was controlled by the K‐feldspar content. It had a much larger impact on the reservoir properties of the Westphalian D as, in these sandstones, K‐feldspar was less affected by eogenetic alteration. The illitization of smectitic clays resulted in illite, quartz and ankerite cementation in both reservoirs. This process had a more important impact on the Westphalian C reservoir, since cementation here also resulted from smectite to illite conversion in the interbedded and underlying shales. The effect of mesogenetic alterations on the reservoir properties was much less drastic than the impact of eodiagenesis. Mesogenetic alterations do exert a significant control on the properties of the Westphalian D. The vast impact of eodiagenesis on the Westphalian C sandstones made them less susceptible to mesogenetic alteration. The effect of telogenetic processes on the porosity and permeability of the Westphalian sandstones was small and restricted to the top reservoir intervals that directly underlie the Cimmerian Unconformity. No significant telogenetic alterations related to the Variscan Unconformity were observed.  相似文献   

17.
Nine Namurian clay bands retrieved from boreholes in the northern part of the Pennine Basin are, on the basis of their petrography, mineralogy and geochemistry, shown to be volcanic in origin and are therefore bentonites. The bentonites, which have a fragmental texture, are normally graded and show rare preservation of shard textures, representing vitric tuff deposits that have been altered subsequently to clay-dominated horizons. Crystals are a minor component of the bentonites, but biotite, in particular, is concentrated at the base of the beds. A clay mineral assemblage of mixed-layer illite–smectite with subordinate kaolinite identifies most of the samples as K-bentonites, but kaolinite dominates two samples that can be classed as tonsteins. Temporal variation of salinity within the depositional basin is suggested to explain these different clay assemblages. The major element geochemistry of the bentonites reflects their clay mineralogy and the compositions of diagenetic minerals present, the latter including pyrite, carbonates and hydroxyapatite. Enrichment of the bentonites in some trace elements (including Ba, Sr, Pb, Cu and Ni) can be related to the presence of the diagenetic minerals, but the extent to which the elements are added from external sources as opposed to being redistributed within the ash is unclear. Immobile trace element systematics suggest a rhyodacite/dacite composition for the original ash and derivation from the collision of plates, this being supported by evidence provided by the rare earth elements (REE) in one group of samples. However, in another group of samples, variations in REE concentrations may be caused by mobility of these elements during alteration. The chemistry of the Namurian bentonites contrasts markedly with that of the local Carboniferous volcanics but is comparable, in some respects, with one group of Westphalian tonsteins, although the latter are more rhyolitic in character. It is suggested that the Namurian bentonites and the Westphalian tonsteins of acid affinities originated from volcanic activity associated with a destructive plate margin in the Variscan externides and that the observed compositional trend may reflect magma evolution possibly related to the progressive east–west closure.  相似文献   

18.
Gondwana basins of Orissa State constitute a major part of the Mahanadi Master Basin. These Gondwana sediments, ranging from Asselian to Albian in age, contain remnants of three basic floral assemblages i.e. Glossopteris Assemblage, Dicroidium Assemblage and Ptilophyllum Assemblage which can be recognized through the Permian, Triassic and Early Cretaceous, respectively. The megafloral assemblages of different basins of this state are discussed briefly. This report mainly deals with the plant species diversification in different lithological formations and the development of flora in the Gondwana basins of Orissa. A number of successive megafloras are recognized. Among those, leaves are the dominant part of the preserved flora, followed by fruits and roots. No wood parts are preserved in the major basins. These pre-angiospermic floras have been systematically analyzed to depict the evolutionary trends, and palaeofloristics of these basins. The distribution of plant fossils in different formations of these basins depicts provincialism in Gondwana flora within the Orissa.  相似文献   

19.
Palaeobotany of Gondwana basins of Orissa State, India: A bird's eye view   总被引：1，自引：0，他引：1  
Gondwana basins of Orissa State constitute a major part of the Mahanadi Master Basin. These Gondwana sediments, ranging from Asselian to Albian in age, contain remnants of three basic floral assemblages i.e. Glossopteris Assemblage, Dicroidium Assemblage and Ptilophyllum Assemblage which can be recognized through the Permian, Triassic and Early Cretaceous, respectively. The megafloral assemblages of different basins of this state are discussed briefly. This report mainly deals with the plant species diversification in different lithological formations and the development of flora in the Gondwana basins of Orissa. A number of successive megafloras are recognized. Among those, leaves are the dominant part of the preserved flora, followed by fruits and roots. No wood parts are preserved in the major basins. These pre-angiospermic floras have been systematically analyzed to depict the evolutionary trends, and palaeofloristics of these basins. The distribution of plant fossils in different formations of these basins depicts provincialism in Gondwana flora within the Orissa.  相似文献   

20.
中国早石炭世小孢子和微古植物地理区   总被引：6，自引：0，他引：6  
高联达 《甘肃地质》1998,7(1):48-58
中国早石炭世地层发育,沉积类型多样,动植物化石众多,研究程度较高。通过讨论中国早石炭世孢子演化事件,微古植物地理分区,沉积环境和古气候,进而探讨了中国早石炭世微古植物群与西欧、北美、前苏联和冈瓦纳大陆微古植物群之间的关系及中国早石炭世古地理位置。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号