HOLOCENE SALINE SEDIMENTARY RECORD IN TIBETAN DONG CO(LAKE) AND ITS SIGNIFICANCE ON PALAEOCLIMATE

Based on the sedimentary characteristics study of Holocene borax\|bearing mirabilite beds of Dong Co(lake) two sections, DZ01 and DZ02, in the center of North\|Tibetan Plateau,combined with dating of 14 C, applied theory and method of comparative salinology, it is determined that the palaeoclimate framework of Dong Co during early\|middle Holocene, and reckoned the range of the temperature variation. Furthermore, after completing regional analogue, discovered that the palaeoclimate environment is fully comparative and consistent with the synchronous lake\|water retreating trace of Zhaduixiong spits in Zabuye Lake basin, with palaeoclimate changes recorded by pollen in adjacent Zabuye Lake, with Holocene plaeoclimate environment indicated by drilling\|hole in Bangong Co,with palaeoclimate significance traced by δ 18 O value in Qinghai Lake and Siling Co and with the palaeoclimate framework during the 5th Level Arid (Salinization) Extension Period of Quaternary arid center of Western China.

RECONSTRUCTING HOLOCENE PALAEORUNOFF REGIMES FROM PALAEOCLIMATE: AN INITIAL ATTEMPT TO APPLY A CLIMATOLOGICAL APPROACH TO PALAEOHYDROLOGY FOR THE NORTH CHINA PLAIN

Employing the regression equations relating mean annual runoff to mean annual temperature and mean annual precipitation derived with modern data, palaeorunoff values were calculated from palaeoclimatic information for three localities in the eastern part of the North China Plain (37-41°N, 115-120°E) during the last 12 000 years. These results present a general pattern of temporal and spatial variations of the Holocene palaeorunoff occurring in this region. The annual runoff was the highest during 8000-3000 a B.P., the second high during 12 000-8000 a B.P., and the lowest during 3000-0 a B.P. Spatially the annual runoff was the highest at the downstream area of the Luanhe River in the north, the second highest at the area around Beijing in the middle, and the lowest at the area around Xingtai in the southwest. These results were further compared to other palaeohydrological reconstruction achieved by other researchers or with other methods, which usually indicates the similar trend of hydrological changes for this region.

The Palaeoclimate Variations in the Central Plains Since the Interstade of the Last Glacial Stage

Through the study of a high-resolution loess record in the Central Plains, the short—term palaeoclimatic variations since the interstade of the last glacial stage have been discussed in this paper. The palaeoclimate in the East Asian monsoon areas shows different variation patterns in summer and winter. A correlation of the palaeomonsoon records of loess with the δ18O records of the ice core and deep sea is made, and some of the causes for their differences are also discussed.

Palaeosol of the Siwalik Group as a 15 Ma Record of Palaeoclimate

Palaeosols are one of the architectural elements of sedimentation in the Siwalik Foreland Basin holding a record of long term climate changes for the past 18 Ma.Systematic study of palaeosols,and associated non-pedogenic materials,along with their parent rock is important for understanding pedogenic processes and environments,which in turn gives insight into the interrelation between climate,topography and ecosystem.The fossil soils have a special value as they remains in the place of their formation

Micropaleontology and palaeoclimate during the early Cretaceous in the Lishu depression,Songliao basin,Northeast China

Diverse and abundant microfossils, such as palynomorphs, algae and Ostracoda, were collected from lower Cretaceous strata of Lishu depression, located in southeastern Songliao basin, and were identified and classified in order to provide relevant, detailed records for paleoclimate research. The early Creta- ceous vegetation and climate of southeastern Songliao basin have been inferred from the analysis of palynomorph genera, algae and Ostracoda of the LSI and SW110 wells. The lower Cretaceous strata include, in ascending stratigraphic order, the Shahezi, Yingcheng and Denglouku formations. Palyno- logical assemblages for each formation, based on biostratigraphic and statistical analyses, provide an assessment of their longitudinal variations. During deposition of the Shahezi Formation, the climate was mid-subtropical. Vegetation consisted of coniferous forest and herbage. During deposition of the Ying- cheng Formation, the climate was south Asian tropical. Vegetation consisted mainly of coniferous forest and herbal shrub. In addition, fresh and saline non-marine water dominated the lacustrine setting during deposition of these formations. Deposition of the Denglouku Formation, however, occurred under a hot and dry tropical climate. The vegetation was mostly coniferous forest and lake waters became saline. Palaeoclimate variation is correlated by the lake level change and the development of sedimentary facies. Palaeoclimate contribute to the formation of hydrocarbon source rocks and reservoir.

New records of Jurassic petrified wood in Jianchang of western Liaoning,China and their palaeoclimate implications

Diverse and rich fossil wood records have been documented from the Mesozoic of Liaoning Province, NE China. The Tiaojishan Formation(mainly distributed in Beipiao, Chaoyang, Fuxin and Jianchang regions) is one of the most significant horizons for the Jurassic petrified wood in Liaoning Province. Previously, wood fossils of this formation were mainly reported in Beipiao and Chaoyang regions, whereas fossil wood record was merely known in Jianchang region. Here we describe new fossil wood specimens from the Tiaojishan Formation in Jianchang County, western Liaoning. Two fossil wood taxa, i.e., Protaxodioxylon jianchangense Tian et Wang sp. nov. and Xenoxylon peidense Zheng et Zhang were recognized on the basis of anatomical features. These fossil wood records add new data for understanding the fossil wood diversity, floral composition and palaeoclimate of the Tiaojishan Formation. The occurrence of Xenoxylon and Protaxodioxylon implies a cool temperate, wet and seasonal climate condition with interannual variations during the Middle to Late Jurassic transition in western Liaoning region.

Jurassic sedimentary evolution of southern Junggar Basin:Implication for palaeoclimate changes in northern Xinjiang Uygur Autonomous Region,China

Junggar Basin,located in northern Xinjiang,presents continuous and multikilometer-thick strata of the Jurassic deposits.The Jurassic was entirely terrestrial fluvial and lacustrine deltaic sedimentation.Eight outcrop sections across the Jurassic strata were measured at a resolution of meters in southern Junggar Basin.Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology,fossils and tectonic setting.In the Early to Middle Jurassic,the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent,and provided adequate moisture for Junggar Basin.Coal-bearing strata of the Badaowan,Sangonghe,and Xishanyao Formations were developed under warm and humid palaeoclimate in Junggar Basin.In the late Middle Jurassic,Junggar Basin was in a semi-humid and semi-arid environment due to global warming event.Stratigraphy in the upper part of the Middle Jurassic with less plant fossils became multicolor or reddish from dark color sediments.During the Late Jurassic,collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea.A major change in climate from semi-humid and semi-arid to arid conditions took place,and reddish strata of the Upper Jurassic were developed across Junggar Basin.

Landscape evolution and palaeoclimate in the deserts of northwestern China,with a special reference to Badain Jaran and Taklamakan

A comparative study of geomorphologic landscapes in the Badain Jaran Desert and Taklamakan Desert was made on the basis of field investigations, thermolumi-niscence and radiocarbon dating as well as analysis of sand grain texture. The sand seas of the Badain Jaran Desert differ greatly from that of the Taklamakan Desert in terms of dune morphology, interdune relief, dune stratigraphy and sand sources. The thermoluminiscence ages of the dunes suggest that the basic configuration of the megadunes in the Badain Jaran Desert has not changed at least since Middle Holocene. There were periods of more humid environment during the last glaciation and Holocene in both deserts, but events of higher precipitation in the Badain Jaran Desert were more frequent than in the Taklamakan. In both desert areas, aeolian processes have been intensified during the last 2000 a.

Quantitative reconstruction of the palaeoclimate of the Shahejie Formation in the Chezhen Depression,Bohai Bay Basin,eastern China

This paper uses pollen climate analysis and coexistence analysis to systematically analyze the climatic evolution of the Shahejie Formation in the Chezhen Depression,Bohai Bay Basin,eastern China and discusses the relationship between palaeoclimatic evolution and lake level rise.The results show that the sedimentary period of the Shahejie Formation in the Chezhen Depression had an overall temperature change trend from hot to cold and simultaneously experienced a dry and wet balance-wet-dry and wet balance-wet transition process.The climatic parameters of the Shahejie Formation in the Chezhen Depression include a mean annual temperature of 8.1℃-15.1℃,a mean coldest monthly temperature of-0.1℃-2℃,a mean warmest monthly temperature of 18.6℃-28℃,a mean annual precipitation of 389-1164 mm,a wettest monthly precipitation amount of 215-262 mm,and a driest monthly precipitation amount of 8-48 mm.Climate change is believed to affect the rise and fall of lake levels to some extent.The quantitative reconstruction of these climatic parameters allows researchers to more intuitively understand the geological background of the Chezhen Depression and guide the exploration and development of oil and gas resources.

Linking evolutionary mode to palaeoclimate change reveals rapid radiations of staphylinoid beetles in low-energy conditions

Staphylinoidea(Insecta:Coleoptera)is one of the most species-rich groups in animals,but its huge diversity can hardly be explained by the popular hypothesis(co-radiation with angiosperms)that applies to phytophagous beetles.We estimated the evolutionary mode of staphylinoid beetles and investigated the relationship between the evolutionary mode and palaeoclimate change,and thus the factors underlying the current biodiversity pattern of staphylinoid beetles.Our results demonstrate that staphylinoid beetles originated at around the Triassic-Jurassic bound and the current higher level clades underwent rapid evolution(indicated by increased diversification rate and decreased body size disparity)in the Jurassic and in the Cenozoic,both with low-energy climate,and they evolved much slower during the Cretaceous with high-energy climate.Climate factors,especially low 02 and high C02,promoted the diversification rate and among-clade body size disparification in the Jurassic.In the Cenozoic,however,climate factors had negative associations with diversification rate but little with body size disparification.Our present study does not support the explosion of staphylinoid beetles as a direct outcome of the Cretaceous Terrestrial Revolution(KTR).We suppose that occupying and diversifying in refuge niches associated with litter may elucidate rapid radiations of staphylinoid beetles in low-energy conditions.

Palaeoclimate background of the diverse Eocene floras of South China

Hainan and Guangdong provinces,located in north tropical area and south subtropical area of China respectively,bear one of the highest levels of biodiversity in China.The modern floras of Hainan and Guangdong are dominated by pantropical and tropical-subtropical taxa and many of their representative families appeared as early as in the Eocene[1].The Eocene,therefore,represents a crucial stage in the formation of the extant flora.However,previously the Eocene floras and vegetation were largely studied in mid-

Biogeographical and palaeoclimate appraisal of mangrove vegetation in South Asia and Southeast Asia in the post Himalayan uplift scenario

Fossil evidence indicates that mangrove species have had their first appearance in the Late Cretaceous(70 65 Ma) and they have evolved around the Tethys seaway after the plate tectonics and the movement of the continents when Tethys Sea was fast closing as the massive continental fragments continued to shift and jostle across the globe. The oldest geological record of Acrostichum and Nypa palm offers good examples as these species prefer low-salinity requirements and have wide ecological tolerance. Such environmental and habitat preferences must have been the probable reason for their initial adaptation to mangrove habitat and a wider distribution. The open sea link must have also provided enough coastal areas for the establishment of mangrove ecosystem and subsequent spreading of the mangroves into newer areas by Early to Middle Eocene(ca 50–40 Ma). However, the mangroves started acquiring the present geographical positions towards OligoceneMiddle Miocene period. The fossil record and the modern analogues of Kandelia, Nypa and Pelliciera indicate that their biogeographical preferences have been shifted due to oceanic reorganization wherein the latter is now confined only to Atlantic East Pacific mangrove realm despite it was earlier widespread in the Tethys Sea. Although Rhizophora and Avicennia differ only at the species level and common occurrence of Acrostichum aureum, the present mangrove distribution shows the contrast in the biogeography of many genera due to geomorphic barriers and climatic changes. The Himalayan uplift and establishment of Asian summer monsoon system towards Late Neogene has also affected the coastal dynamics considerably which in turn modified the distribution of mangrove vegetation of the Indian subcontinent. The loss of sensitive habitats, disjunct distribution of a few species and local extinction of significant taxa has affected the overall biogeography of mangroves in South and SE Asia.

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.

Evidence of the Pan-Lake Stage in the Period of 40-28 ka B.P. on the Qinghai-Tibet Plateau

The Qinghai-Tibet plateau is one of major saline lake regions in China, where saline lakes are widespread and constitute an important object of researches on the palaeoclimatic change in the region. On the basis of comprehensive investigations of the evolution of the lake's surface and sediments on the plateau, the authors have further demonstrated the existence of a pan-lake stage (river and lake flooding stage) on the Qinghai-Tibet plateau during the period of about 40+-28 ka B.P. and analyzed the palaeoclimatic characteristics of the pan-lake period and relationships between the ancient monsoons and the uplift of the plateau since the beginning of the Quaternary.

Cenozoic plant diversity of Yunnan： A review

Yunnan in southwestern China is renowned for its high plant diversity.To understand how this modern botanical richness formed,it is critical to investigate the past biodiversity throughout the geological time.In this review,we present a summary on plant diversity,floristics and climates in the Cenozoic of Yunnan and document their changes,by compiling published palaeobotanical sources.Our review demonstrates that thus far a total of 386 fossil species of ferns,gymnosperms and angiosperms belonging to 170 genera within 66 families have been reported from the Cenozoic,particularly the Neogene,of Yunnan.Angiosperms display the highest richness represented by 353 species grouped into 155 genera within 60 families,with Fagaceae,Fabaceae,Lauraceae and Juglandaceae being the most diversified.Most of the families and genera recorded as fossils still occur in Yunnan,but seven genera have disappeared,including Berryophyllum,Cedrelospermum,Cedrus,Palaeocarya,Podocarpium,Sequoia and Wataria.The regional extinction of these genera is commonly referred to an aridification of the dry season associated with Asian monsoon development.Floristic analyses indicate that in the late Miocene,Yunnan had three floristic regions:a northern subtropical floristic region in the northeast,a subtropical floristic region in the east,and a tropical floristic region in the southwest.In the late Pliocene,Yunnan saw two kinds of floristic regions:a subalpine floristic region in the northwest,and two subtropical floristic regions separately in the southwest and the eastern center.These floristic concepts are verified by results from our areal type analyses which suggest that in the Miocene southwestern Yunnan supported the most Pantropic elements,while in the Pliocene southwestern Yunnan had abundant Tropical Asia(Indo e Malaysia)type and East Asia and North America disjunct type that were absent from northwestern Yunnan.From the late Miocene to late Pliocene through to the present,floristic composition and vegetation types changed markedly,presumably in response to altitude changes and coeval global cooling.An integration of palaeoclimate data suggests that during the Neogene Yunnan was warmer and wetter than today.Moreover,northern Yunnan witnessed a pronounced temperature decline,while southern Yunnan experienced only moderate temperature changes.Summer precipitation was consistently higher than winter precipitation,suggesting a rainfall seasonality.This summary on palaeoclimates helps us to understand under what conditions plant diversity occurred and evolved in Yunnan throughout the Cenozoic.

Sedimentary cycles of trace elements in Salawusu River Valley since 150 ka BP

The paper makes some analyses on 11 trace elements in the Milanggouwan stratigraphical section in the Salawusu River valley, which is regarded as a prototype geology-palaeoclimate record since 150 ka BP. The results show that the content and variation of trace elements has experienced remarkably regular changes in the pace with coarse and fine sedimentary cycles of palaeo-aeolian sands to its overlying fluvio-lacustrine facies or/and palaeosols. The trace elements with chemical properties of relatively active (V, Sr, Cu, Ni, As) and relatively stable (P, Pb, Rb, Mn, Nb, Zr) are a manifestation of the corresponding 27 changeable cycles between peak and valley values, appearing a multi-fiuctuational process line of relative gathering and migration since then. The low numerical value distribution of these two types of trace elements in the aeolian sand facies represents erosion and accumulation under wind force during the cold-dry climate. Whereas their enrichments in both fluvio-lacustrine facies and palaeosols are related to the valley’s special low-lying physiognomic position between the Ordos Plateau and the Loess Plateau under the warm and humid climate conditions. The above relatively migrated and gathered change of the trace elements is the result of 27 climatic cycles of cold-dry and warm-humid, which is probably caused by repeated alternations of winter monsoon and summer monsoon in the Mu Us Sandy Land influenced by the climate vicissitudes in northern hemisphere during glacial and interglacial periods since 150 ka BP.

A Carbon Isotopic Stratigraphic Pattern of the Late Palaeozoic Coals in the North China Platform and Its Palaeoclimatic Implications

This paper gives the stable carbon isotopic data in coals from the Late Namurian to Kazanian stages in the Serteng Mt., Xishan and Huainan coalfields of the North China Platform. Its stratigraphic pattern shows that several isotopic shifts are apparent, and the large δ13C negative shifts (approximately 2.5 to 3.0 %%) occurred during the Stephanian, Artinskian and Kazanian are observed in three Permo-Carboniferous coalfields. Those negative shifts are neither related to the coal rank and coal macerals, nor caused by the variety of peat-forming plants. The general decrease in the δ13C values of the Stephanian, Artinskian and Kazanian coals is consistent with an overall decrease in the δ13C values of ambient atmospheric CO2 and/or a relative increase in atmospheric Pco2 during the coal-forming periods. Therefore the authors postulate that the oxidation of peat, and the δ13C-depleted CO2 flux into the atmosphere during the above stages may have contributed to coeval palaeoclimatic warming by way of the greenhouse effect.

Quaternary Climate and Environment in the Lop Nur,Xinjiang

Since the middle Early Pleistocene (1.20 Ma B.P.), the desert steppe climate and environment have predominated in the Lop Nur area, Xinjiang, characterized by warm humid epochs interrupted by dry cold intervals. The grain-size and magnetic susceptibility curves record 30 climatic oscillations, each with a ca. 40 ka cycle, in the area since 1.2 Ma B.P., which reflects the controlling effects exerted by the astronomic factor on the environment. The Quaternary sedimentary environment in the Lop Nur gradually changed from a fresh lake through a brackish lake to a saline lake, showing a spiral evolution, and finally it evolved into a playa.

Early Miocene flora of central Kazakhstan(Turgai Plateau) and its paleoenvironmental implications

The investigation of the fossil floras from the Turgai plateau (central Kazakhstan) contributes to a better understanding of the origin of the temperate Turgai type flora which spread to Kazakhstan and adjacent areas during the Oligocene-Miocene transition. In this paper, we present the results of a carpological and palynological study of the Kumyrtas flora collected from a flora-bearing horizon of the regional coalbearing Zhilanchik suite, dated to the Aquitanian period. Pollen analysis identified 33 taxa, with are dominated by angiosperms (about 73%) and reflect zonal vegetation. The high percentages of Betula (27%) and Pterocarya (7.5%) that were found in this flora allows comparisons with other Aquitanian floras of Kazakhstan. Based on descriptions of fossil fruits and seeds, we determined that 19 taxa were dominant;these taxa had meosphytic herbaceous components, suggesting mostly edaphic local conditions. The incongruence between the carpological and the pollen records suggests a significant taphonomical effect. Quantitative reconstruction of the palaeoclimate based on pollen records supports—and slightly extends—previous findings based on fossil leaf data, but contradicts findings deduced from the carpological record. Plant Functional Type (PFT) classification was used to characterize the vegetation patterns. Pollen records show that about 45% of diversity relates to the arboreal broadleaved deciduous components and ca. 35% to conifers. Fossil fruit and seed data indicate riverine vegetation with a high diversity of aquatic components and shrub stratum.

Environmental record from the mud area on the inner continental shelf of the East China Sea since the mid-Holocene

Paleoclimate record was revealed in Core MZ01 covering the mid-Holocene in age,located in the mud area of the inner continental shelf of the East China Sea. The ancient environment featured low-energy shallow sea shelf deposition formed mainly by coastal currents. The results show that temporal variation in geochemistry corresponds with the climate changes inferred from historical record. Relatively low MgO/Al 2 O 3,CaO/K 2 O and high Al 2 O 3 /Na 2 O,K 2 O/Na 2 O,MnO/CaO values reflected a warm and humid climate in general,and vice versa. Therefore,these chemical indices could be applied to identify the variation of palaeoclimate in eastern China. The authors reconstructed the history of mid-Holocene climatic variation of the inner continental shelf of the East China Sea. From 8 300 a BP to 4 200 a BP,the climate was moderately warm and humid. From 4 200 a BP to 2 000 a BP,the climate turned cool and dry,and the regional climate frequently fluctuated in alternation of cool-dry periods（3 700 a BP,2 850 a BP and 2 400 a BP） and warm-wet periods（3 250 a BP and 2 650 a BP） . After 2 000 a BP,the climate of the study area gradually turned warm again,while the Little Ice Age,a cold event centered at around 250 a BP was indicated by those geochemical indices as mentioned above.