Palynology and stratigraphy of the thick evaporate-bearing Shashi Formation in Jiangling Depression,Jianghan Basin of South China,and its paleoclimate change

In the greater inland Jianghan Basin of South China,three salt depressions are lacking accurate geological times,of which Jiangling Depression is the largest.Evaporites are important records of paleoclimate,however,the geological ages of evaporates are very difficult to be determined because often evaporates have scare macrofossils and microfossils.Nonmarine Cretaceous to Tertiary halite deposits interbedded with mudstones are widely distributed in China.Paleocene-Eocene Thermal Maximum had very high temperatures and attracted strong interests of geologists because these times can be compared with future climate change because of global warming.However,previous studies focused on marine sediments found that during the Paleocene-Early Eocene,massive evaporate deposits formed in Jiangling depression of the Jianghan Basin.In this paper,the authors show that the Shashi Formation halite deposits formed in the Paleocene according to palynology.Most of these palynology fossils are arid types,so the massive evaporites in the Jiangling depression could be closely related to the hot Paleocene climate.High temperatures during the Paleocene contributed to the formation of the massive evaporates in the Jiangling Depression,until sylvite was the result.

Progress, problems and prospects of palynology in reconstructing environmental change in inland arid areas of Asia

Studying the climatic and environmental changes on different time scales in inland arid regions of Asia can greatly im‐prove our understanding of climatic influences for the Qinghai-Tibet Plateau in the context of global change. Pollen, as a remnant of seed plants, is sensitive to environmental factors including precipitation, temperature and altitude, and is a clas‐sic proxy in environmental reconstruction. In the last two decades, great progress in the application of palynology to in‐land areas of Asia has highlighted the role of palynology in paleoclimatic and paleoenvironmental research. The main progress is as follows. (1) On the tectonic time scale of the late Cenozoic, the palaeoclimatological sequence has been es‐tablished on the basis of pollen percentage, concentration and taxon. Pollen data have revealed a continuous enhancement of drought in the inland arid region of Asia, in contrast to evidence acquired based on other proxies. (2) In the late Quater‐nary, an increase in herbaceous plants further supports the intensification of drought associated with global cooling. In more detail, the palynological record shows a glacial-interglacial pattern consistent with changes in global ice volume. (3) The Holocene pollen record has been established at a high resolution and across a wide range of inland areas. In general, it presents an arid grassland environment in the early Holocene, followed by the development of woody plants in the mid- to late-Holocene climate optimum. This pattern is related to moisture changes in areas dominated by the westerlies. There are also significant regional differences in the pattern and amplitude of vegetation response to the Holocene environment. (4) Modern pollen studies based on vegetation surveys, meteorological data and statistics show that topsoil palynology can better reflect regional vegetation types (e. g., grassland, meadow, desert). Drier climates yield higher pollen contents of drought-tolerant plants such as Chenopodioideae, Ephedra, and Nitriaria, while contents of Artemisia and Poaceae are greater under humid climates. Besides these achievements, problems remain in palynological research: for example, pol‐len extraction, identification, interpretation, and quantitative reconstruction. In the future, we encourage strengthened inter‐disciplinary cooperation to improve experimental methods and innovation. Firstly, we should strengthen palynological classification and improve the skill of identification;secondly, laboratory experiments are needed to better constrain pol‐len transport dynamics in water and air;thirdly, more rigorous mathematical principles will improve the reliability of re‐constructions and deepen the knowledge of plant geography;and finally, new areas and methods in palynology should be explored, for example DNA, UV-B and isotopic analysis. It is expected that palynology will continue to develop, and we hope it will continue to play an important role in the study of past climatic and environmental changes.

Late Cretaceous-Paleogene Formation of the Bekrit Syncline, Middle Atlas, Morocco: Sedimentology, Geochemistry, Palynology and Paleoenvironments

Globally, the Paleogene period experienced several events marking the Paleocene-Eocene transition which is especially to one of the hottest periods that the Earth has ever known (Paleocene-Eocene Thermal Maximum, PETM), followed by the biological crisis that affected benthic foraminifera. The Bekrit Syncline, subject of this study, shows three Formations of range from the Cretaceous to the Eocene ages (the El Koubbat, Irbzer and Bekrit-Timahdite Formations). Sedimentological, palynological and geochemical analyses of collected samples, in the Bekrit syncline, were studied to determine the paleogeographic and paleoenvironmental conditions of the Middle Atlas. The carbonate rocks were analyzed by microscopic study and geochemical analysis by X-ray Fluorescence (XF) and Inductively Coupled Plasma Spectrometry (ICP). The results obtained highlight the sedimentary events that took place during the Paleogene. Thus, the Maastrichtian is characterized by a closed euxinic marine environment shared by a more open and oxidizing environment. On the other hand, the Paleocene was a restricted marine environment with evaporitic sedimentation, while the Eocene sees the installation of a carbonate platform with a bioclastic Shoal.

Fifty years of Quaternary palynology in the Tibetan Plateau

Quaternary palynology in the Tibetan Plateau(TP)was initiated in the 1960s to meet the needs of economic development in western China.Pollen analysis was conducted for the first time on a 200-m long core of Quaternary lacustrine sediments taken from the main body of the TP in order to study pollen assemblages as well as vegetation and climate changes of glacial(cold)/interglacial(warm)periods.Pollen analysis of alpine snow and ice began at the first scientific expedition to the TP in the 1970s.After the 1980s,a series of international collaborative programs were carried out under Sino-French,Sino-German,Sino-Australian,and Sino-American cooperation,marking the integration of Chinese Quaternary palynology society with the international community.New methods for Quaternary palynology were gradually promoted and applied,changing the vegetational and climatic interpretation of Quaternary palynology from qualitative to quantitative.Since the 1990s,many palynologists have carried out extensive Quaternary palynological studies on fossil pollen sites of more than 60 lakes/sections and alpine glaciers in the TP to discuss the spatiotemporal vegetation changes and climatic and environmental evolution of the TP since the Pleistocene.Over the past half-century,Quaternary palynology in the TP has contributed to the establishment of the Chinese Quaternary pollen database and the study of vegetation and climate evolution since the Last Glacial Maximum(LGM)in the TP.Currently available pollen records revealed the spatial and temporal distribution of vegetation in the TP since the LGM,exhibiting expansions and shrinkages of forest,meadow,grassland and desert in different periods such as the LGM,the last deglaciation,and Holocene optimum period.The paleomonsoon reflected by paleovegetation since the LGM has undergone the changes of weak-strengthening-strong-weakening but still active-shrinking,which is mainly affected by solar insolation.

Palynology and stratigraphy of the Upper Miocene Chad Formation, Bornu Basin,northeastern Nigeria

Both lithological and palynological analyses were employed to decipher sedimentary stacking patterns and to date the sediments within the interval 50—325 m in Kemar-1 well,Bornu Basin,northeastern Nigeria.Eight different lithofacies units deposited in various environments were recognized.They are:(1) the grayish sandy claystone,rich in organic matter and associated with lignite,deposited in a continental to lacustrine environment;(2) the micaceous claystone,rich in muscovite flakes and organic matter,deposited in a lacustrine environment;(3) the lithified claystone which intercalates the dark gray shale,and deposited in a marine setting;(4) the shale;(5) the micaceous sandstone,which is characterized by presence of muscovite,silty to granular grain sizes,well sorted and deposited in a meandering setting;(6) the poorly-sorted sandstone.It is poorly sorted,poorly-graded,and coarse-grained,with erosive surfaces to underlying facies,and deposited in a fluvial environment;(7) the heterolithic clayey sandstone,poorly graded,grayish,with a degree of organic richness,suggesting an anoxic lacustrine environment;and(8) the grayish claystone which is nonlithic and rarely ferruginized marking the Upper Miocene/Eocene boundary.One main palynological zone,i.e.,the Echitricolporites spinosus assemblage zone,has been established.The base of the studied section at 385 m is characterized by the last up-hole occurrence of Grimsdalea magnaclavata suggestive of Eocene boundary while the overlying sediments are characterized by Late Miocene marker species such as E.spinosus,Elaeis guineensis,Anthocerus sp.,Nymphaea lotus,and Retistepho.nocolpites gracilis.The Chad Formation is dated as Late Miocene age unconformably overlying the Eocene Kerri-Kerri Formation which indicated that the Chad Formation was probably deposited during an alternation of lacustrine and continental settings,due to climatic change.

The influence of organic sources and environments on source rock deposition during the periods of Cretaceous–Eocene and Oligocene–Miocene,northern Kalimantan

The sedimentary system of Kalimantan has undergone significant development since the Oligocene.Previous research have largely ignored the capacity of the Cretaceous–Eocene sediments to produce hydrocarbons,focusing instead primarily on the Oligocene–Miocene coal as the principal source rocks.Shales and coals from the outcrops in the northern margin of Kalimantan were analyzed with palynological and geochemical methods to characterize the palaeoenvironmental and palaeoecological differences between the Cretaceous–Eocene and the Oligocene–Miocene samples.The high proportion of Cheirolepidoaceae,Schizaeoisporites and Ephedripites in the pollen assemblage from the Cretaceous–Eocene outcrops reflects an arid tropical/subtropical climate.The relatively low abundances of gymnosperm-derived biomarkers including isopimarane,β-phyllocladane,β-kaurane,suggest the gymnosperm features in flora.High C_(27)/C_(29)ααα20R sterane ratios,(C_(19)–C_(29))tricyclic terpanes/C_(30)αβhopane and extremely low oleanane/C_(30)αβhopane,bicadinane T/C_(30)αβhopane,and diterpenoid abundance indicate that there was a dominance of algae relative to higher plants in the organic matter.The gymnosperm-derived biomarkers,including isopimarane,β-phyllocladane,β-kaurane,suggest that palaeovegetation during this period was dominated by gymnosperms.The saline and reducing conditions in the bathyal and abysmal sea,evidenced by rather low Pr/Ph and high Gammarerane index,are beneficial for the preservation of hydrogen-rich organic matter.It is presumed that the Cretaceous–Eocene shales had great hydrocarbon generation potential in the southern South China Sea.During the period of Oligocene to Miocene in the Zengmu Basin and the Baram-Sabah Basin,the climate changed to a dominant humid and warm condition,which is corroborated by abundant pollen of Florschuetzia and Magnastriatites hawardi.Low C_(27)/C_(29)ααα20R sterane ratios,(C_(19)–C_(29))tricyclic terpanes/C_(30)αβhopane,and high oleanane/C_(30)αβhopane,bicadinane T/C_(30)αβhopane suggest that the palaeovegetation was dominated by angiosperms including the mangrove plants.The extremely abundant higher plants provide ample terrigenous organic matter for the formation of coal-measures in delta facies.The low gammacerane index and high Pr/Ph indicate the fresh and sub-oxic water in delta-neriticabysmal faces,which is not beneficial for the accumulation of hydrogen-rich organic matter.Thus,the Oligocene–Miocene marine argillaceous rocks can be potential sources of natural gas.

Palynological Evidence of Late Pleistocene Soft-sediment Deformation Event in the Northeastern Margin of the Tibetan Plateau

The northeastern margin of the Tibetan Plateau is the youngest part of the Tibetan Plateau where tectonic activity is intense and climate change is complex.In this study,combined with field investigations,we explored accelerator mass spectrometry 14C and optically stimulated luminescence dating and palynological analysis of the sedimentary sequence in the Qingshuihe Basin to explain the origin of soft-sediment deformation layer.Dating and palynological results from the Sanchahe section in the basin revealed a detailed history of vegetation variation and associated climate change from~18 to~5 ka BP.The results indicate that the permafrost developed at~18–11.7 ka BP,and the soft-sediment deformation structures formed at~11.7–5 ka BP.Together with the characteristics of the deformation(meter-scale,continuous symmetrical wave)and paleoclimate,we suggest that the soft-sediment deformation layer in the late Pleistocene was cryoturbated under climatic conditions.The discovery of a series of cryoturbations in the Qingshuihe Basin has further enriched the regional distribution of periglacial phenomena in the west of the Ordos Plateau,expanded the distribution range of periglacial phenomena,and provided evidence for exploring the temporal and spatial changes in permafrost in northern China at the end of the late Pleistocene.

Bamboo Leaf and Pollen Fossils from the Late Miocene of Eastern Zhejiang,China and their Phytogeological Significance

Fossil bamboo leaves and pollen from Upper Miocene deposits of the Shengxian Formation in Tiantai and Ninghai counties, eastern Zhejiang, China represent a rare record in Asia. The distinctive pseudopetiole and parallel venation of the leaf blades and the clearly thickened annulus of the pollen aperture place them in the subfamily Bambusoideae. Morphological analysis supports the determination of these fossil leaves as belonging to the genus Bambusium and two new species are described. Bambusium latipseudopetiolus Q.J. Wang et B.N. Sun sp. nov. has a distinctly wide pseudopetiole of 0.23 cm in width and 0.40 cm in length, several vascular bundles on parallel veins, and 5-8 lateral veins on both sides of the midrib. Bambusium longipseudopetiolus Q.J. Wang et B.N. Sun sp. nov. has a distinctly long pseudopetiole of 0.60 cm in length and 0.10 cm in width, several vascular bundles on the pseudopetiole, and 6 lateral veins on both sides of the midrib. Pollen grains from the same layer provide additional evidence of bamboos. They are characterized by 32.0-51.0 μm in diameter, a round pore 3.0-4.0 μm in diameter with a broad thickened annulus 2.5-3.5 μm around, and several conspicuous secondary folds on the exine surface. The morphological analysis leads to their assignment to Graminidites bambusoides Stuchlik. These fossils are important for the study of bamboo phytogeography in China. They demonstrate that there were bamboos growing in southeastern China during the Late Miocene and that bamboos in Zhejiang begin to diversify no later than the Late Miocene. In combination with bamboo fossils from other places, it seems that bamboos had a wide distribution across southern China during the Miocene, ranging from southwestern Yun＇nan to southeastern Zhejiang.

Stratigraphy of the Triassic-Jurassic Boundary Successions of the Southern Margin of the Junggar Basin,Northwestern China

The Triassic-Jurassic （Tr-J） boundary marks a major extinction event, which （～200 Ma）resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr-J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected： the Late Triassic （Rhaetian） Aratrisporites-Alisporites Assemblage, the Early Jurassic （Hettangian） Perinopollenites-Pinuspollenites Assemblage, and the Sinemurian Perinopollenites-Cycadopites Assemblage. The Tr-J boundary is placed between bed 44and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha （？）, Unio-Ferganoconcha and Waagenoperna-Yananoconcha bivalve assemblages are recognized. The Ferganoconcha （？） bed is limited to the upper Haojiagou Formation,Unio- Ferganoconcha and Waagenoperna- Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine-littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian.

Stable Carbon Isotopic Composition of Black Carbon in Surface Soil as a Proxy for Reconstructing Vegetation on the Northern Slope of the Qinling Mountains

Because of the unique geographical location and important ecological effect of the Qinling Mountains, reconstruction of its vegetation and climate needs comprehensive research. We need to consider a multiple-proxy approach to gain more information on recovering the paleovegetation and climate in the Qinling Mountains. Black carbon （BC） is produced by the incomplete combustion of vegetation and fossil fuels, and is a good proxy, recording paleoenvironmental information. However, in the Qinling Mountains, what are the characteristics of the BC, and whether BC stable carbon isotope （δ^13CBc） can be used as a new proxy to study ancient vegetation, still need further study. In order to establish a sound basis for studying paleoenvironmental by BC proxy in the Qinling Mountains, we carried out systematic and detailed study on modern process of BC on the northern slope of the mountains. We analyzed stable carbon isotopes and carbon concentration of organic carbon （% SOC, δ^13Csoc） and BC （%BC, δ^13CBc）, and identified the pollen assemblages from systematically sampled surface soil. The results show that the calculated ratio of C4 plants in the vegetation （%C4） based on the δ13Csoc data reflects a similar distribution of C4 plants in the surface vegetation and the pollen assemblage. The δ^13Cac values have a strong positive correlation with δ13Csoc values, and their difference （△13CSOC-BC） is in the low range. These data indicate that δ^13CBC and δ^13CSOC have very similar characteristics. Surface soil δ13BC values can indicate surface vegetation as effectively as δ^13Csoc values, and the δ^13CBC proxy can be used effectively in paleovegetational research in the northern slope of Qinling Mountains.

Palynological Analysis of Amber-Bearing Clay from the Lower Cretaceous of Central Lebanon

An amber-bearing lignitic layer of sandy clay from the Lower Cretaceous of Central Lebanon （Mderej-Hammana）yielded a well-preserved,moderately variegated palynoflora,which origin is mixed between land plants and marine microflora.Its detailed analysis led to fulfill its inventory,to propose a paleoenvironmental reconstruction,and to draw the paleoclimate which prevailed over the region：an estuarian area under a rather humid,temperate climate;a variety of ferns grew near the shore-side and in the inward land.A tiny piece of amber containing angiospermous pollen grains of stratigraphical interest allows a precise dating.The marine microflora,poorly diversified,includes chitinous foraminifer linings and dinoflagellate cysts,among which Early Aptian guide taxa are present;their occurrence slightly narrows the stratigraphical range indicated by some palynological taxa which are related to land plants.

Middle and Late Permian palynoflora in Tianshan Township,southeast of Bogda Mountain,Xinjiang,China

The Permian is one of the most important periods during which the vegetative earth witnessed the transition from icehouse to greenhouse climate and the global environment changes.Organisms on the planet encountered great challenge and the demise of swamp caused the extinction of arborescent lycopods and the rising of Mesophytic plants accomplished the floral transition from the Paleophytic to Mesophytic vegetation.In order to depict the climatic changes and floral succession in the middle and high latitudes of the North Hemisphere,palynological investigation was engaged,and 40 samples collected from the uppermost of Taerlang Formation,Hongyanchi Formation and Quanzijie Formation in the Tianshan Town,Turpan-Hami Basin,eastern Xinjiang,China.The result shows that the palynoflora in the studied area is composed of 50 species of 33 genera,dominated by disaccites and striatiti gymnosperm pollen,and characterized by diverse Protohaploxypinus,Hamia-pollenites,Alisporites and Klausipollenites.It is quite similar to those Middle and Late Permian palynological assemblages reported in the Dalongkou section and other localities in southern margin of Junggar Basin,and aged at Middle and Late Permian.The diversity of typical Angara and sub-Angara pollen,such as Falcisporites,Alisporites,Protohaploxypinus,Vittatina,Lunatisporites,Hamiapollenites,etc.indicates that the studied palynoflora belonged to the sub-Angara phytoprovince,while the presence of Lueckisporites virkkiae implied Euramerica pollen intruded northward sometimes.The paleoclimate of the studied area might be warm and humid with fluctuated dry seasons during the late Guadalupian and early Lopingian time.

Late Cretaceous-Paleogene Palynostratigraphy from the Arkhara-Boguchan Brown Coal Mine of Zeya-Bureya Depression, Russia

A well-preserved Late Cretaceous-Paleogene palynological flora from the middle member of the Tsagajan Formation and the upper member of the Tsagajan Formation including the Kivda Beds is reported for the first time from the Arkhara-Boguchan brown coal mine, southeastern part of the Zeya-Bureya Basin. Four palynocomplexes were established for the Cretaceous-Tertiary transition. The climate and phytocoenoses were also analyzed,based on the detailed palynological data. The results are coincident with those of mega-flora studied by Akhmetiev et al. (2002).

Peat Accumulation and Early Carboniferous Environments of the Kizel Coal Basin,the Urals,Russia

The lithological and geochemical composition and conditions of formation of the coal-bearing deposits of the Kizel Coal Basin in the Perm region of the Urals(central Russia)are described using the two most representative sections,Gubakha-Stary Most and Krestovaya Mountain,based on a detailed“layer-by-layer”technique.Brief characteristics of the Lower Carboniferous paleosols from fossil paleosol(FPS-)profiles of the studied region are given.Special attention is paid to the parent vegetation of the coal-forming processes,based on an analysis of both plant macrofossils and palynoflora.The peat accumulation in conditions of permanent incoming of clastic material from the Paleo-Urals to the Kizel Basin was probably effective only in more or less stable environments,when the accumulated organic matter produced by plant mortmass was not dissolved by clastic particles.Thus,the conditions of coal-forming are reconstructed as a forest swamp,where the main dominants are represented by lycopodiopsids of the order Lepidodendrales,predominantly Lepidodendron veltheimii.These plants in particular were the source of the initial organic matter for the peat(and later coal)of the Kizel Coal Basin.

Environment and Age of the Upper Devonian‒Carboniferous Zhulumute and Hongguleleng Formations,Junggar Basin,NW China:Ichnological and Palynological Aspects

Two Upper Devonian to Lower Carboniferous sections,namely the Bulongguoer and Haer(Gennaren area)in the Junggar Basin,Central Asian Orogenic Belt,in northwestern China were examined with regard to ichnology and palynology.The deposits of the Hongguleleng Formation and Namu Member of the Heishantou Formation,respectively,are mostly unbioturbated or poorly bioturbated,with poorly diversified trace fossils,which indicate unfavourable conditions for the burrowing benthic community during the Late Devonian and Early Carboniferous.The main factor governing the growth of the bioturbating population was the rapid sedimentation of fine-grained,volcanic material documented as tempestites,which buried the benthic fauna.In the Bulongguoer section,the presence of miospores Teichertospora torquata and Grandispora gracilis enabled identification of the broad Teichertospora torquata–Grandispora gracilis Miospore Zone from the transitional Frasnian/Famennian interval.More accurate identification of palynostratigraphical levels(DE and CZ Miospore zones)is only tentative.On the basis of palynofacies analysis,samples from the lower Bulongguoer section indicate deposition in more proximal conditions,whereas samples from the top of the section indicate deposition in a more distal environment.In the Haer section,only a general biostratigraphic indication for the Tournaisian was possible,owing to poor preservation of organic matter.

Reconstruction of Natural Climatic Conditions for the Last 10000 Years in the Komi Republic,NW Russia(From Palynological Data)

Investigation included palynological analysis and radiocarbon dating of the Holocene lake,alluvial (Oxbow lake)and swamp sediments in middle and northern Taiga subzones of the Komi Republic.On the basis of cores from three boreholes and fourteen outcrops,synchronous spectra correlation and Holocene separation were accomplished.Mean annual and July temperatures were estimated by

A palynotaxonomic study of the genus Filipendula (Rosaceae)

Pollen grains from 15 species （18 taxa） of the genus Filipendula were examined with light and scanning electron microscopy. It was revealed that the pollen grains are isopolar, tricolporate, with scabrate or scabrate-microechinate surface. The pollen morphology was compared with the conventional classification systems of the genus by different authors, and supported Shimizu＇s system （1961）, in which the genus was divided into three subgenera. The monotypic subgen. Hypogyna is characterized by pollen lacking fastigium and thickened costae colpi. The other monotypic subgen. Filipendula differs from others by pollen having larger grain, larger pore size, longitudinally elliptic fastigium and thickened costae colpi. The largest subgen. Ulmaria is distinguished by pollen having rounded or latitudinally elliptic fastigium and thickened costae colpi. Sectional classification was not supported by the pollen morphology due to insufficient variability. Key words Filipendula, palynology, systematics.

Palynological assemblage in the late Early Cretaceous from Sikouzi Section, Liupanshan Group, Central China and its implication to paleoenvironment change

The Cretaceous(ca.145 Ma^65 Ma)was characterized by remarkable greenhouse conditions which was more server than present greenhouse gas emissions.However,this special climate condition is mainly documented from marine records.The information derived from continental sediments including terrestrial vegetation is relatively scarce.Here,we report on a palynological study of 17 samples from the Lower Cretaceous Liupanshan Group of the Sikouzi Section(spanning116 Ma^103 Ma),Liupanshan Basin and analyzed for paleoclimate implications.The palynoflora is diverse,dominated by Classopollis(Cheirolepidiaceae),with abundant ferns and rare angiosperms.The dominant ferns are from Lygodiaceae and Schizaeaceae.The palynological data shows that the Early Cretaceous floras are derived from various settings,i.e.,the Coniferales on high elevation mountains,Cheirolepidiaceae along low hills near lakes,ferns in marsh wetlands,and algae in fresh water lakes.The palynoflora indicates that the climate in the Liupanshan area is hot and dry,and the palaeogeography is characterized by complex and various outlook during the Early Cretaceous,furthermore,climate evolution revealed by the vegetation can be divided into two stages during this period.From 116 Ma to 112 Ma,the concentration of thermophilic and xerophilous species such as Cheirolepidiaceae and Schizaeaceae were relatively low,conifers increased significantly,and fern concentration remained steady.This ecosystem suggests a humid and cold climate during this period.From 112 Ma to 103 Ma,the concentration of Cheirolepidiaceae and Schizaeaceae was relatively high,and conifers decreased significantly.Compared to the upper stage,the total percentage of Lygodiaceae spores were relatively low.Vegetation change during this period may indicate an increased trend of a dry and hot environment in this region.The trend of climate change recorded by the pollen assemblages during this period coincide with global sea surface temperature fluctuation.Thus,climate change recorded by the palynological assemblage in the Sikouzi section correlates well with global climate change during the Early Cretaceous.