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In this paper, the stratigraphic occurrence of n -alkanes (C n) is investigated in three peat cores (Mildred, JPH4 and McMurray) from the ombrotrophic peatlands in northeastern Alberta, Canada, to determine their origin, biomass input, and paleoclimatic significance. The molecular composition of n -alkanes is dominated by the >C 21 medium- to long-chain homologues, with a strong odd over even predominance. A number of n -alkane-based indices (e.g. predominant n -alkane, C 23 /C 29 , C 23 /(C 27 + C 31), P aq , ACL, and CPI), show changing conditions in the organic matter (OM) input from Sphagnum species or terrestrial vascular plants, which increasingly contributed upwards in the peat profiles, and through time. P aq and C 23 /(C 27 + C 31) proxies are similar in the three cores, and allow us to infer vegetation variations that coincide with the climate alternations of the Medieval Warm Period (MWP), Little Ice Age (LIA), and modern Recent Warming (RW). The utilization of ACL-ket and (C 23 + C 25)/(C 27 + C 29 + C 31)-ket proxies, performed in comparison with n -alkane proxies, further support the biomarker-based reconstructions of paleoclimate variations over recent centuries. This study suggests that n -alkane homologues are sensitive to vegetation and climate changes and thus are reliable biomarkers for tracking past shifts in vegetation and climate variations in peat archives. • Determine organic matter source of peat sediments from n -alkane biomarkers. • C 23 /(C 27 +C 31) n -alkane proxy is proposed and can effectively characterize climate changes. • P aq proxy indication could be misleading when the contribution of Sphagnum fuscum to the peat is large. • n -Alkan-2-one proxy is studied to further confirm the biomarker-based reconstruction of paleoclimatic changes. [ABSTRACT FROM AUTHOR]

Abstract This special issue of Palaeogeography Palaeoclimatology Palaeoecology on "Cenozoic Climate Change in Eastern Asia" contains a series of multidisciplinary studies representing a wide range of research on paleovegetation, sedimentology, clay mineralogy, geochemistry, magnetostratigraphy, and climate modelling. The general significance of these studies is that analysis of terrestrial paleoclimate changes in eastern Asia may offer insights into the effects of Tibetan Plateau uplift, and ultimately the dynamic processes of global change that took hold throughout the Cenozoic. The present volume is Part II of this special issue. The first part of the special issue was dedicated to understanding eastern Asian paleoclimate variation during the Cenozoic by especially evaluating proxy data from geochemistry and climate modeling. Part II includes additional geochemical studies of terrestrial deposits from different regions of eastern Asia as well as climate modeling. Some of these papers focus on the impact or effect of these climatic changes on various floras and faunas in this region. In these studies, the period investigated ranges from the Eocene to the middle Holocene, thus encompassing most of the Cenozoic. Collectively, these studies provide significant new insights into the Cenozoic paleoclimate framework of eastern Asia. [ABSTRACT FROM AUTHOR]

The Tajikistan (TJ) loess has great significance for the study of Quaternary climate changes and dust source in Central Asia. In this paper, we investigate the geochemical composition and provenance of loess. Our results show that the major elements, in order from high to low average content, are SiO 2 > Al 2 O 3 > CaO > Fe 2 O 3 > MgO > K 2 O > Na 2 O > TiO 2 > P 2 O 5 > MnO. Fe, Ti, P and Mn contents in loess are similar to those in the UCC, as is the case with Si, Al and Mg contents in paleosols. Ca is distinctly enriched in loess, and Si, Al and K are depleted. Na is depleted in both loess and paleosols, and P is depleted only in paleosols. In contrast to the UCC, paleosols show enrichments in all trace elements except for Ba, Sr and Zr, but in loess, some trace elements (e.g., Ba, Co, Ni and Zr) show depletion. The CIA value of TJ loess is lower than that of Kashmir loess, the latter being influenced by differences in the sorting and tectonic environment. There are no great changes about provenance during the formation of TJ loess, and the deposit areas have a shorter distance to the provenance. Geochemical data and atmospheric circulations demonstrate that the TJ loess was mainly transported by the near-surface northerly or northwesterly winds, but there may be an additional and local source making a certain contribution to the formation of loess deposits in the south of Tianshan. [ABSTRACT FROM AUTHOR]

Studies dealing with the reconstruction of Holocene climate change of tropical areas are scarce. Of these, multi-proxy investigations using peatlands are still absent. In this paper, we present the Holocene record of environmental changes in central–eastern Brazil reconstructed from a core sampled in Pau de Fruta mire (Serra do Espinhaço Meridional, Brazil). We combined palynological and geochemical analyses, supported by core stratigraphy, 14 C dating and multivariate statistics. The location of the mire is ideal because it is in an area which is directly associated with the South Atlantic Convergence Zone (SACZ). Six main phases of change suggested by vegetation and local and regional landscape dynamics were described. In phase I (~ 10,000–7360 cal. yr BP) the climate was very wet and cold and was accompanied by soil instability in the mire catchment (severe local erosion) and the 8.2 ka event was easily recognizable by a large increase in the deposition of regional dust. Phase II (~ 7360–4200 cal. yr BP) was characterized by wet and warm conditions, catchment soil stability and enhanced deposition of regional dust. In phase III (~ 4200–2200 cal. yr BP), climate was dry and warm and soil erosion in the catchment increased again. In phase IV (~ 2200–1160 cal. yr BP) dry and punctuated cooling was reconstructed, together with enhanced deposition of regional dust. Phase V (~ 1160–400 cal. yr BP) reflects sub-humid climatic conditions (like the current climate), the lowest inputs of local and regional dust and the largest accumulation of peat in the mire. While in phase VI (< ~ 400 cal. yr BP) sub-humid conditions continued but both local and regional erosion significantly increased. Our results demonstrate that the tropical peatlands of Serra do Espinhaço Meridional contain relevant records of Holocene climate changes, and that a multi-proxy approach offers good opportunities for a detailed reconstruction of palaeoenvironments. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates changes in the vegetation and hydrology at Ljubljansko barje (Slovenia) using a multi-proxy approach (pollen, diatoms, geochemical and stable isotope analysis). During the Lateglacial Ljubljansko barje was a deep, oligotrophic lake surrounded by open woodland comprised predominantly of Pinus and Betula which in the early Holocene, when the lake became shallower and mesotrophic (Fragilaria pinnata, δ 15N~3.3‰, δ 13C~−33.7‰, C/N~7.9), was replaced by broadleaved tree taxa (Tilia, Ulmus, Quercus, Corylus) and Picea. This was followed by the spread of Fagus and after ~9200 cal yr BP Abies and planktonic and oligotrophic diatom taxa (Aulacoseira italica, Gomphonema angustum) as well as an increased allochthonous influx (silt, SiO2, Al2O3). Between ca. 6750 and 6000 cal yr BP the diatom data suggest shallower and oligotrophic conditions, whereas the stable isotope record (increased δ 13C and decreased δ 15N) indicates terrestrial input. Changes in forest composition (increase of Quercus, Alnus, Corylus) and the spread of herb taxa were probably advanced by human impact on the environment. The beginning of organic sedimentation, dated to 6000 cal yr BP, was followed by an increase of Fagus and Abies and by eutrophication and peat growth at ~5200 cal yr BP. [Copyright &y& Elsevier]

With a record that spans approximately 300 million years (late Cambrian through the Triassic/Jurassic transition, i.e., the "Conodontozoic"), conodonts witnessed all principal events in the evolution of life on Earth, from the invasion of the land to the exploration of the air, from the explosion of biomineralization in the oceans to the rise of dinosaurs and mammals, including three of the major extinction events that occurred in the Phanerozoic. Mainly used for biostratigraphic or geochemical studies, the potential of conodonts to help unravel changes perceived to be of global extent rarely has been explored. While specialists have identified rapid changes in conodont element morphology throughout their history, the conodont animal has often been perceived to have been a static entity in a constantly evolving world, when biological equilibrium in the oceans was undergoing profound alteration and faunal recoveries took place in phases that seem to have had recurrent patterns. It is now essential that we begin to further investigate how conodonts, as biologic entities, responded to or were impacted by palaeogeographic changes, eustatic and climatic fluctuations, shifting redox conditions, and major faunal turnovers and reorganizations that took place during the "Conodontozoic". • Introductory paper to a special volume on conodonts. • Conodonts represent a unique archive of information for over 300 million years. • Global oceanic events can be traced and their temporal pattern precisely calibrated by conodonts. [ABSTRACT FROM AUTHOR]