Sporopollen Assemblage Research Articles

Northward expansion of Cenozoic Asian humid climate recorded by sporopollen

The distribution pattern of arid–humid climate in the modern northwest–southeast confrontation in Asia evolved from the zonal distribution pattern of the Paleogene. However, this evolutionary process remains poorly constrained by geological evidence. In this paper, we analyze the characteristics of sporopollen assemblages recorded in Late Eocene strata of the Jianchuan Basin in southwest China. We show that vegetation patterns exhibited a remarkable shift from tropical–subtropical sparse forest to subtropical–temperate mixed broad-leaved–coniferous forest at ∼40.6 Ma; this shift is further indicated by the rapid decrease in drought-tolerant plants, mostly Ephedra and Chenopodiaceae, evidence that the previous hot–dry climate was replaced by a warm–humid climate at this time. This evidence suggests that the Asian monsoon began to affect the study area at ∼40.6 Ma. We then comprehensively integrated sporopollen results from several basins across East Asia, revealing that the frontal edge of the humid monsoon climate moved intermittently to the northwest after the Late Eocene, and may have advanced to the Lunpola–Lanzhou line by the early Late Oligocene, this being similar to the position of the leading edge of the modern monsoon. Moreover, the frontal edge of the humid monsoon climate may have extended as far as the Qaidam Basin during the Middle Miocene, but then gradually retreated to the position of the modern monsoon front. The uplift of the Tibetan Plateau and global climate change may have played dominant roles in this evolution.

Long‐term arid and hot climate during earlyMid‐Cretaceousindicate by unvaried Cheirolepidiaceae‐dominant palynoflora from the Liupanshan Basin, China

The Mid‐Cretaceous was characterized by long‐term and stabilized high temperatures confirmed by numerous palaeoclimatic information from marine sedimentary archives. However, few terrestrial records have yet been employed to verify the terrestrial humidity under this long‐term hot climate. The Liupanshan Basin, located in central China during the Cretaceous contains thick Aptian‐Albian sediments. Here, we reconstructed a long‐term palaeovegetational record during late Aptian to Albian from the Huoshizhai Section and Sikouzi Section, Liupanshan Basin. Five palynological assemblages were defined from the bottom to top of these strata, and a total of 124 types of palynomorphs including 47 spore species and 77 gymnosperm pollen species were recognized in the palynological assemblages. Sporopollen analysis revealed that the spore‐pollen spectra of Huoshizhai Section were dominated byPerinopollenitesand Bisaccate pollen. In Sikouzi section, theClassopolliscontent dominate in all samples (average 63.8%), with a few other pollen, including conifer bisaccates types,Perinopollenites,Jiaohepollis,Ephedripites,Cycadopitesand a few spores. The sporopollen assemblage reflected that the flora of the central Asia continent gradually changed from Taxodiacean‐dominated to Cheirolepidiaceae‐dominated in the late Aptian and the Albian, which further indicates that the central Asia continent palaeoclimate gradually changed from a wet and cold climate to a long‐term dry and hot climate with small fluctuation. In addition, theClassopolliscontent also presented a slightly increased trend from late Aptian to late Albian, which probably indicated a gradually intensified hot and dry climate. The thermophilic floral changes and warmer/cooler ratio of the Sporomorph Ecogroup Model at the middle Madonghshan Formation also shows slightly decreased trends which correspond to the global short‐term cooling events at the Aptian‐Albian transition.

Paleo-vegetation and paleo-climate characteristics of Cretaceous and Paleogene strata in several typical basins in China: palynological evidence

ABSTRACT The paleovegetation and paleoclimate characteristics are studied in the Palaeogene strata of Hetao Basin, Subei Basin and Qaidam Basin in China, and the Cretaceous Guyang Formation (K1 g) in the Hetao Basin. These three basins receive high attention, different distribution areas, representative. Pollen evidence shows that: (1) The sporopollen assemblage of Palaeogene Linhe Formation (E3 l) in Hetao Basin is characterised by Pinaceae-Ephedripites-Ulmipollenites-Chenopodipollis. It reflects that the ancient vegetation types were mainly coniferous and evergreen woody plants, and the climate was cold temperature. The sporopollen assemblage characteristics of the upper member of the Palaeogene Xiaganchaigou Formation (E3 2) in the Qaidam Basin are similar to it. (2) The sporopollen characteristics of the K1 g in the Hetao Basin reflect that its ancient vegetation was dominated by evergreen woody plants and belongs to a warm and humid subtropical climate. (3) The assemblage of Palaeocene Funing Formation (E1 f) in Subei Basin was Pterisisporites undulatus-Ulmipollenites minor-Taxodiaceaepollenites hiatus. The climate type was humid north temperate climate, vegetation was mainly deciduous trees and evergreen woody plants. (4) Leiosphaeridia/Granodiscus, Pediastrum and Botryococcus were also detected in the E1 f of Subei Basin. The appearance of these algae indicates the special saline water environment and good hydrocarbon potential.

Palynoflora and climatic dynamics of the Laizhou Bay of Bohai Sea, North China Plain, since the late middle Pleistocene

The coastal plain of Laizhou Bay in Bohai Sea is a transitional area of land–sea interaction. Sediments in this area can bear significant information of sea-level fluctuation, climate change, as well as regional geological setting. Here, in this study, new sporopollen data from three boreholes (GK138, GK111 and GK95) in the coastal plain of Laizhou Bay, Bohai Sea were investigated, and the pollen spectrum since the late middle Pleistocene was established as six sporopollen assemblage zones (I–VI), i.e., Pinus–Quercus–Artemisia, Gramineae–Artemisia–Chenopodiaceae, Picea–Pinus–Quercus–Artemisia, Picea–Pinus–Betula–Gramineae–Artemisia, Picea–Pinus–Cupressaceae–Chenopodiaceae and Pinus–Quercus–Gramineae–Artemisia–Chenopodiaceae. Combining with existing sedimentary successions and detailed radiocarbon dating results of the sediments from the three boreholes, paleovegetation and climatic evolution since the late middle Pleistocene were reconstructed. The findings revealed that climatic changes in this area since the late middle Pleistocene were characterized by alternating cold-arid and warm-humid conditions, which were well correlated with marine isotopic stages (MIS). The present study offers specific insight into the climatic dynamics in the North China Plain since the late middle Pleistocene and provides evidence of a clear link among the palynoflora in the area, the glacial–interglacial period climate-driven sea-level changes, and the marine δ18O records.

The relationship between paleoclimate change and paleosedimentary environment identification in coastal areas

Based on the close relationship between paleoclimate change and paleosedimentary environment, the relationship and influence between paleoclimate change and paleosedimentary environment identification in coastal areas were further studied. Taking the coastal areas of Zhejiang Province as the study area, the soil samples of the coastal areas of Zhejiang Province were collected by BZK1 borehole, and the samples were preliminarily treated and identified by optical microscope. The foraminifera, Ostracoda, and grain size were identified, and the paleosedimentary environment was analyzed by mapping. The results show that the coastal strata in Zhejiang can be divided into four stages according to the changes of sporopollen assemblage, species distribution, abundance, and diversity of foraminifera and Ostracoda. Since the late Pleistocene, the general trend of climate change in the study area is warm-wet, warm-wet and warm-wet, and gradually turns to cold-dry, which is consistent with the change of sea level fluctuation. According to the general trend of paleoclimate change in the study area, the paleosedimentary environment of the study area is further analyzed by the characteristics of grain size parameters and grain size composition. According to the depth, the sediments can be divided into seven stages. Since late Pleistocene, the sediments are mainly silt. The changing process of hydrodynamic conditions during deposition is medium energy-medium low energy-medium energy-medium low energy-medium energy. The changes of sedimentary facies are as follows: shore shallow lake, flood plain, shallow lake beach bar, lake swamp, flood plain, and shallow sea swamp.

Discovery of Late Jurassic Sporopollen Assemblage from the Tamulangou Formation in the Hongqi Sag of the Hailar Basin, Inner Mongolia, China

Acta Geologica Sinica - English EditionVolume 94, Issue 5 p. 1718-1720 Research Advance Discovery of Late Jurassic Sporopollen Assemblage from the Tamulangou Formation in the Hongqi Sag of the Hailar Basin, Inner Mongolia, China Chuanbiao WAN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYunfei XUE, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYuewu SUN, Corresponding Author sunyuewu@jlu.edu.cn Key Laboratory for Evolution of Past Life and Environment in Northeast Asian (Jilin University), Ministry of Education, Changchun, 130026 ChinaCorresponding author. E-mail: sunyuewu@jlu.edu.cnSearch for more papers by this authorYanping HOU, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYudong JIN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorXin ZHANG, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorTi LI, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this author Chuanbiao WAN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYunfei XUE, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYuewu SUN, Corresponding Author sunyuewu@jlu.edu.cn Key Laboratory for Evolution of Past Life and Environment in Northeast Asian (Jilin University), Ministry of Education, Changchun, 130026 ChinaCorresponding author. E-mail: sunyuewu@jlu.edu.cnSearch for more papers by this authorYanping HOU, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYudong JIN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorXin ZHANG, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorTi LI, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this author First published: 08 October 2020 https://doi.org/10.1111/1755-6724.14590AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume94, Issue5October 2020Pages 1718-1720 RelatedInformation

Evolution Characteristics and Stratigraphic Division of Quaternary Sedimentary in the South Wing of Yangtze River Delta, East China

This paper discusses the sporo pollen assemblage, evolution of sedimentary environment, sedimentary facies and the lithotope characteristics revealed by boreholes since pliocene epoch by carrying out 14C dating, sporo pollen and micro-paleontological analysis of sediments in borehole BK01 (depth 237.80 m) in the southern flank of the Yangtze River Delta Plain. According to the results of this study, there are 17 species of foraminifera that have been identified as 11 genera, including 16 benthic foraminifera and 1 planktonic foraminifera；8 species of Ostracoda that have been identified as 8 genera; sporo pollen analysis shows that there are 37 types, including 18 species of woody plant pollen, 11 species of herbaceous plant pollen, 8 species of fern spores, of which, in the sporo pollen assemblage, woody plants have the highest content (about 85.1%), ferns spores have about 8.7%, and herbaceous plants have only 6.3%. Sedimentary environment records can be divided into 18 sporo pollen assemblage zones according to borehole lithology, sporo pollen assemblage and micropaleontology analysis. The results show that the BK01 bore strata from bottom to top can be divided into carbonaceous mudstone (Ech), Jiaxing Formation (N-Qp1j), Qiangang Formation (Qp2q) Dongpu Formation (Qp3d), Ningbo Formation (Qp3n) and Zhenhai Formation (Qhzh).

A Research of the Cretaceous-Paleogene Boundary in the Pingyi Basin, Shandong Province

The Bianqiao Formation (in the Pingyi Basin, Shandong Province, China) is a typical set of continuous lacustrine carbonate deposits during the Cretaceous-Paleogene period, which is considered as an ideal stratigraphic unit for KPB research. This study is based on the borehole PYZK01, which is located at Tongjiazhuang village in Bianqiao Town of Pingyi country. According to biostratigraphy research, the Bianqiao Formtion establishes one charophyte assemblage: Porocharaanluensis-Charayuntaishanensis var. acuta-Turbocharaspecialis, and one sporopollen assemblage: Deltoidosporaadriensis-Rugubivesiculites- Schizaeoisporites. This result indicates that the stratigraphic age during 0 - 12.25 m is the Paleogene, 37.8 m - 60 m is the Late Cretaceous, and 12.25 - 37.8 m is a transition stage from the Late Cretaceous to the Paleocene. By geochemical study, it was established carbon and oxygen isotopic strata in the drill. Through the magnetostratigraphy research, we find eight positive polarity zones and seven reversed polarity zones, build the magnetic polarity sequences of the borehole, and propose a contrast scheme with the international standard magnetic polarity time column. After comprehensive discussion, it is preliminarily believed that the Cretaceous-Paleogene boundary is located at the depth of 31.98 m in PYZK01, namely, in the first section of the Bianqiao Fm.

Quaternary Sediments and Paleoenvironmental Evolution in Suqian Region

Based on the BK2 hole of Suqian active fault detection and seismic hazard assessment project, The Quaternary comprehensive geological profile of Suqian area is analyzed and presented by the methods of lithology description, lithofacies classification, stratigraphy dating, grain size analysis and palaeospheric sporopollen sample analysis, the Quaternary Sediments and Paleoenvironmental Evolution in Suqian area are discussed. The main achievements and understandings obtained are as follows: 1. Through the grain size test and analysis, we can conclude the changes of sedimentary motivation and sedimentary environment: the sections generally experienced Qp1-2 (alluvial-diluvial of medium and high energy) → Qp2-1 zone (high-energy alluvial-diluvial) → Qp2-2 zone (middle-high energy alluvial-diluvial) → Qp2-3 zone (middle-low energy alluvial-diluvial) → Qp3-1 zone (Alluvial-diluvials→ Qp3-2 (middle and high energy alluvial-diluvials) →Qh-1 (low-lying lacustrine sediments) →Qh-2(Middle and low energy fluvial deposit) .2. According to the sporopollen map, the sporopollen assemblage of BK2 borehole since Quaternary in Suqian area was divided into 9 sporopollen assemblage zones. Based on the sporopollen assemblage, lithology and dating data, the sporopollen assemblage zone I, II represents the last interglacial age and the last glacial age respectively; The sporopollen assemblage zones III, IV and V represent warm and dry in the early postglacial stage, warm and humid in the middle, and warm and wet in the late stage, respectively.3, Palynological assemblages reflect the vegetation types and climate evolution during Quaternary period in Suqian city, BK2 hole of 9 Palynologicalassemblages corresponding to the type of vegetation and climate types: the early Pleistocene (coniferous and broad-leaved mixed forest, warm and humid), the earlier of mid-Pleistocene (coniferous-steppe, cold-dry), the mid of mid-Pleistocene (coniferous-broad-leaved mixed forest, warm and humid), the later of Middle Pleistocene (coniferous forest-steppe, warm and dry), the earlier of Late Pleistocene (coniferous and mixed forest, warm and humid), the later of Late Pleistocene (coniferous and mixed forest-grassland, cool and wet.) the early Holocene (spare deciduous broad-leaved forest-grassland, cool and dry) the mid-Holocene (spare deciduous broad-leaved forest-grassland, warm and moist, coniferous and broad-leaved mixed grassland,) the late Holocene (spare deciduous broad-leaved forest - grassland, warm and humid).

Characteristics of mixed sporopollen assemblage from sediments of Dushanzi mud volcano in southern Junggar Basin and indication to the source of mud and debris ejecta

In order to search for the source of muddy eruption debris, a series of erupted mud samples were collected from a corn of the Dushanzi mud volcanoes in southern Junggar Basin, NW China and analyzed for palynological records. Two palynomorph groups were revealed in the mixed sporopollen assemblage from the erupted sediments according to their colors. The light color group, accounting for about 95% of the total, was dominated by the Chenopodiaceae and Artemisia and in a color of faint yellow, indicating an immature stage of organic matter evolution. The dark color group was composed of Cyathidites, Classopollis, Schizaeoisporites, Lygodiumsporites and Rugubivesiculites, in a color of brown yellow, indicating a low maturity to maturity stage of organic matter evolution. The palynomorph records suggested that most of the muddy debris ejecta of the Dushanzi mud volcano might be sourced from the Cenozoic deposits, mainly the Middle-Late Miocene Taxihe and Dushanzi Formations, and a small portion likely from the Lower Cretaceous Tugulu Group. In addition, there is also a possibility that a little part of eruption debris is from the Upper Jurassic Qigu Formation. The Dushanzi anticline occurred strong extrusion and thrust faults in the late Himalayan period, and the oil and gas reservoirs were destroyed and resulted in eruption of the mud volcano in the Dushanzi area.

Late Cenozoic climates of low-latitude East Asia: A paleobotanical example from the Baise Basin of Guangxi, southern China

A middle Pleistocene flora from a low latitude of southern China was paleoclimatically studied through a quantitative reconstruction. The fossiliferous layer is correlated to the fourth terrace of the local Youjiang River and its age is revised to be the middle Pleistocene based on the presence of Paleolithic stones in the fourth terrace. The Coexistence Approach was applied to the plant fossil materials, combined from both leaf fossils and a sporo-pollen assemblage collected and extracted from the Changsheling Formation. The reconstructed temperatures show that southern China was slightly cooler in the middle Pleistocene than today, which is consistent with the global middle Pleistocene cooling trend in the Quaternary. The mean annual range of temperature from the fossil site appears larger compared to present, implying a somewhat higher seasonality of temperature in the middle Pleistocene. The reconstructed rainfall pattern suggests that the low latitude region in southern China experienced a relatively low rainfall seasonality resulted from the impact of weaker-than-present winter and summer East Asian monsoons during the middle Pleistocene. Furthermore, this overall wetter condition throughout the year during the middle Pleistocene transition provides additional evidence to support the conclusion from other coeval terrestrial records such as vermiculated red soils across southern China. The cooler-than-present temperature and reduced summer precipitation at the fossil site may indicate that the fossil site belongs to a glacial phase.

Early Pliocene paleo-altimetry of the Zanda Basin indicated by a sporopollen record

Whether the uplift of the Tibetan Plateau (TP) led to the origin and development of the Indian monsoon is still in dispute. A helpful indicator would be greater knowledge about the chronological development of paleo-altimetry. The Zanda Basin, located on the SW margin of the TP, forms one of the most extensive Cenozoic sedimentary basins in Tibet. The modern climate of this area is controlled by the Indian Monsoon circulation system. It is thus an appropriate region for the study of paleo-altimetry, in addition to research into the relation between the TP and the Indian Monsoon. Sporopollen analyses of early Pliocene lacustrine strata in the Zanda Basin show that gymnosperm pollen is dominant (av. 77%) and mainly composed of Picea (av. 27.2%) and Abies (av. 24.2%); fern spores occupy a lesser proportion (av. 17.6%), while angiosperm pollen including temperate, sub-tropical broadleaved trees, shrubs and herbs, accounts for only a small proportion of the assemblage. This sporopollen assemblage suggests that sub-alpine dark coniferous forests were distributed around the basin and grow in a cool and wet climate, rather than in a modern alpine steppe environment. These characteristics indicate that the Zanda Basin's altitude throughout the early Pliocene was most probably lower than it is at present.

Tectonics and Topography of the Tibetan Plateau in Early Miocene

Abstract:Early Miocene stratigraphy, major structural systems, magmatic emplacement, volcanic eruption, vegetation change and paleo‐elevation were analyzed for the Tibetan Plateau after regional geological mapping at a scale of 1:250,000 and related researches, revealing much more information for tectonic evolution and topographic change of the high plateau caused by Indian‐Asian continental collision. Lacustrine deposits of dolostone, dolomite limestone, limestone, marl, sandstone and conglomerate of weak deformation formed extensively in the central Tibetan Plateau, indicating that vast lake complexes as large as 100,000–120,000 km2 existed in the central plateau during Early Miocene. Sporopollen assemblages contained in the lacustrine strata indicate the disappearance of most tropical‐subtropical broad‐leaved trees since Early Miocene and the flourishing of dark needle‐leaved trees during Early Miocene. Such vegetation changes adjusted for latitude and global climate variations demonstrate that the central Tibetan Plateau rose to ca. 4,000–4,500 m and the northeastern plateau uplifted to ca. 3,500–4,000 m before the Early Miocene. Intensive thrust and crustal thickening occurred in the areas surrounding central Tibetan Plateau in Early Miocene, formed Gangdise Thrust System (GTS) in the southern Lhasa block, Zedong‐Renbu Thrust (ZRT) in the northern Himalaya block, Main Central Thrust (MCT) and Main Boundary Thrust (MBT) in the southern Himalaya block, and regional thrust systems in the Qaidam, Qilian, West Kunlun and Songpan‐Ganzi blocks. Foreland basins formed in Early Miocene along major thrust systems, e.g. the Siwalik basin along MCT, Yalung‐Zangbu Basin along GTS and ZRT, southwestern Tarim depression along West Kunlun Thrust, and large foreland basins along major thrust systems in the northeastern margin of the plateau. Intensive volcanic eruptions formed in the Qiangtang, Hoh‐Xil and Kunlun blocks, porphyry granites and volcanic eruptions formed in the Nainqentanglha and Gangdise Mts., and leucogranites and granites formed in the Himalaya and Longmenshan Mts. in Early Miocene. The K2O weight percentages of Early Miocene magmatic rocks in the Gangdise and Himlayan Mts. are found to increase with distance from the MBT, indicating the genetic relationship between regional magmatism and subduction of Indian continental plate in Early Miocene.

Sedimentary environment changes of the Ningshao Plain since the later stage of the Late Pleistocene: Evidence from palynology and stable organic carbon isotopes

A 45.3-m long core was collected from near the Hemudu civilization site (Luojiang county, Zhejiang Province; 29°59.064′N, 121°21.754′E), which is located in the Ningshao plain on the southern margin of Hangzhou Bay. The core, named the HMD Core, was divided into seven lithological layers with clay and silt as the main lithological components. The sporopollen assemblages of this core combined with TOC/TN and stable organic carbon isotope (δ13CTOC) analysis revealed the sedimentary environmental changes since the later part of the Late Pleistocene in the Ningshao plain. The study area changed from terrestrial fluvial-flood plain facies before Marine Isotope Stage (MIS) 3 to shore plain during transgression in MIS3, and became a freshwater lake during regression at the time of the Last Glacial Maximum (LGM). The area started to become a semi-salt lake influenced by sea water during 15,900–5000 cal. BP, in which time period the lake was deeper and the climate became gradually warmer. Later the seawater withdrew, the lake began desalinating, and then became swampy and accumulated peat until 1000 cal. BP. After that, the area became dry land. The results also indicate that the sediments of the core are of endogenous organic origin and the δ13CTOC value was controlled by change in the concentration of atmospheric CO2, and thus was a response to global changes.

Reply to comment on “Regional climate-driven C3 and C4 plant variation in the Cheollipo area, Korea, during the late Pleistocene” by J. Lim, W.-H., Nahm, J.-K., Kim, D.-Y., Yang [Palaeogeography, Palaeoclimatology, Palaeoecology 298 (2010) 370–377

Ouyang et al. (2013--in this issue) raise two concerns regarding carbon isotope analysis and its use for reconstructing past vegetation changes recently published by Lim et al. (2010). One issue questions the formation of sedimentary organic matter by competitive contribution of C3 and C4 plants and calculation of the relative contributions of C3 and C4 plants with a binary mixing model using their mean δ13C values. The second issue questions the use of the δ13C value of flora from other regions or of the current flora as a universal reference to determine the composition of plants in the remote past, pointing out the importance of understanding the exact assemblage of local plants in the past by complete sporo-pollen assemblage analysis and molecular biomarker analysis. In response to these concerns, we provide a detailed description of the tracing process for determining the source of sedimentary organic matter using δ13C values and C/N ratios, and assess the suitability of calculating the relative contributions of C3 and C4 plants using a binary mixing model. Finally, based on its advantages compared to other biological proxies, we explain the utility of using δ13CTOC values for reconstructing past vegetation changes.

High-resolution climate evolution derived from the sediment records of Erlongwan Maar Lake since 14 ka BP

Varve counts with AMS 14C, 137Cs and 210Pb dating of sediments (0–900 cm) from Erlongwan Maar Lake, NE China were used to establish a high-resolution chronology series for the late Quaternary. Dry density, total organic carbon (TOC) content, total nitrogen (TN) content, TOC/TN ratios and stable organic carbon isotope (δ 13Corg) ratios were continuously analyzed on this sediment profile. On the basis of lithological characters, sporo-pollen assemblages and geochemical analyses, we identified 6 climate stages within the last 14 ka BP. The time before the Holocene (14-11.4 ka BP) represents a higher-order oscillation climatic transitional period (I). The entire Holocene climate development (from 11.4 ka BP to present) exhibited an increasing temperature trend, although there were cold and warm alternations (II–VI). The periods included were: II (11.4-9.05 ka BP) warm-wet stage, III (9.05-7.4 ka BP) cold and warm fluctuation stage, IV (7.4-4.2 ka BP) smoothly warming climate stage, V (4.2-1.67 ka BP) climate optimum stage, and VI (from 1.67 ka BP to present) cool and drier stage. Each climate stage began with a warming event and ended with an abrupt cooling event. This climate change cycle had unequal time spaces that were progressively shorter over time. Several abrupt climate shifts occurred at about 9.4-9.05, 8.5-8.2, 7.8-7.4, 4.6-4.2, 3.7-3.25, 2-1.67 and 0.3-0.03 ka BP. Thus, it can be seen that the climate has been warming since 1920 AD, which indicates a new climate stage.

Sporopollen and algae research of core B106 in the northern South China Sea and its paleoenvironmental evolution

Based on the high-resolution sporopollen and algae research of the sediments from core B106 in the northern South China Sea, three sporopollen assemblage zones have been distinguished in ascending order: Zone 1 (294–194 cm): Pinus-Quercus (evergreen)-Gramineae-Polypodiaceae- Pterdium-Dicranopteris. Zone 2 (194–94 cm): Pinus-Quercus (evergreen)-Polypodiaceae-Pteridium- Dicranopteris. Zone 3 (94–4 cm): Pinus-Polypodiaceae-Pteridium-Quercus (evergreen)-Dicranopteris. The three sporopollen zones correspond to three stages of vegetation, climate and paleoenvironment evolution of the northern part of the South China Sea since 11 000 years ago. Combined with AMS 14C dating, the sporopollen and algae data can be a scientific basis for stratigraphic division and reconstruction of paleoclimate and paleoenvironment in the South China Sea.

Sporopollen Assemblages from the Cretaceous Yimin Formation of the Hailar Basin, Inner Mongolia, China

Abstract Three sporopollen assemblages are recognized for the first time from the Cretaceous Yimin Formation in the Hailar Basin of eastern Inner Mongolia. They are (in ascending order): the Impardecispora-Aequitriradites-Clavatipollenites assemblage; the Triporoletes-Pilosisporites-Asteropollis assemblage; and the Appendicisporites-Asteropollis-Tricolpites assemblage, distributed in Members 1,2 and 3 of the Yimin Formation respectively. Recognition of this biostratigraphic sequence is very important for the division and correlation of the Yimin Formation in the basin. Meanwhile, the age of the Yimin Formation is considered to be Barremian to Early Albian based on the palynological data.

Sporo-pollen assemblage and paleoclimate events in shelf area of the southern Yellow Sea since 15 ka B. P.

Based on the authors’ 1986 to 1994 sporo-pollen assemblage analysis in the southern Yellow Sea area, data from 3 main cores were studied in combination with14C, palaeomagnetic and thermoluminescence data. The evolution of the paleoclimate environments in the southern Yellow Sea since 15ka B. P. was revealed that, in deglaciation of the last glacial period, the climate of late glaciation transformed into that of postglaciation, accompanied by a series of violent climate fluctuations. These evolution events happened in a global climate background and related to the geographic changes in eastern China. We distinguished three short-term cooling events and two warming events. Among them, the sporo-pollen assemblage of subzone A1 showed some cold climate features indicating that a cooling event occurred at about 15-14ka. B. P. in early deglaciation. This subzone corresponds to the Oldest Dryas. In subzone A3, many drought-enduring herbal pollens and some few pollens of cold-resistantPicea, Abies, etc. were found, which indicated that a cooling event, with cold and arid climate, occurred at about 12-11ka. B. P. in late deglaciation. This subzone corresponds to the Younger Dryas. The sporo-pollen assemblage of zone B showed warm and arid climate features in postglaciation. Although the assemblage of subzone B2 indicated a cold and arid climate environment, the development of flora in subzone B2 climate was less cold than that in A3. Subzone B2 indicated a cooling event which occurred at about 9ka B. P. in early olocene. Subzone A2, with some distinct differences from subzone A1 and A3, indicated a warming event which occurred at 14-13ka. B.P. and should correspond to a warming fluctuation. The sporo-pollen assemblage of zone C showed features of warn-moist flora and climate, and indicated a warming event which universally occurred along the coast of eastern China at 8-3 ka B. P. in middle Holocene, and its duration was longer than that of any climate events mentioned above. This period was climatic optimum and belonged to an altithermal period in postglaciation.

Vegetational and environmental changes in the last 350ka in erlangjian, qinghai lake

本文依据青海湖南岸二郎剑阶地QH-86孔(深155m)中200余个孢粉样品的分析资料,将该孔深78m以上的孢粉图式,从下至上划分出七个区域性孢粉带,并结合铀系法测年数据,论述了350ka B.P.来的湖区植被和环境演变。其气候曲线与毗邻的柴达木盆地,甚至与深海钻孔及洛川黄土,具有可对比性。;Qinghai Lake is situated in the northeastern margin of the Qinghai-Xizang Plateau, i. e. a boundary area of East Asia monsoon with very sensitive climatic and vegetational changes. In accord with cold and semiarid climate, the vegetation zone of Qinghai Lake region belongs to high cold shrub steppe and meadow. In the provious papers based on the information of sporo-pollen assemblages by radio-carbar dating, the authors (Du et al. 1989, Kong et al. 1990) preliminary have pictured the vegetational and climatic changes in the last 11000 a. Unfortunately, vegetational and climatic succession was so short that only a little is known about the environmental changes since pleistocene. The pollen analytical investigation of 155m-deep-QH86 core from Er-longjian terrace in Qinghai Lake has been carried out. (Fig. 1) For sporo-pollen analysis on 200 samples collected from core-QH86, 90 samples are qualified for statistics. Based on the characteristics of QH86 core sporo-pollen assemblage along with ²³⁰Th dating, seven pollen zones may be subdivided in an ascending order as follows:(Fig. 2) In zone Ⅰ(342-275ka B. P.), zone Ⅱ (230-175ka B. P.) and zone V_c(83-63ka B. P.) the vegetation belongs to temperate steppe mixed by a few trees. During those periods some hydrophytes, such as Typha, myriophyllum, pediastrum boryanutn and ferns apparently increased. The climate was relatively warm and wet. It is emphasized that the vegetation and natural environment changed violently in Qinghai Lake region between 39 and 26 ka B. P. (pollen zone VI) the vegetation was dominant in a subalpine conifer forest consisting of picea, pinus Abies and etc. Such broad-leaved deciduous trees as Betula, Ulmus Quercus meight grow in conifer forest. Lakes and bogs were well developed. In contrast with zone VI, zone I (275-230ka B. P.), zone IV (175-120ka B. P.) and zone VI (63-39ka B. P.) the vegetation was represented by temperate shrub, semi-shrub and steppe, consisting of predominant Chenopodiaceae, Artemisia, Ephedra, Nitraria and Gramineae. In those periods trees, ferns and algae were obviously reduced due to dry and cold climate. It is pointed out that palynalagical evidence is still shot for some layers during 730-350ka B. P. in QH86 core. So it is necessary to make further investigations.