Quaternary glaciations in the Verkhoyansk Mountains, Northeast Siberia

Geomorphological mapping revealed five terminal moraines in the central Verkhoyansk Mountains. The youngest terminal moraine (I) was formed at least 50 ka ago according to new IRSL (infrared optically stimulated luminescence) dates. Older terminal moraines in the western foreland of the mountains are much more extensive in size. Although the smallest of these older moraines, moraine II, has not been dated, moraine III is 80 to 90 ka, moraine IV is 100 to 120 ka, and the outermost moraine V was deposited around 135 ka. This glaciation history is comparable to that of the Barents and Kara ice sheet and partly to that of the Polar Ural Mountains regarding the timing of the glaciations. However, no glaciation occurred during the global last glacial maximum (MIS 2). Based on cirque orientation and different glacier extent on the eastern and western flanks of the Verkhoyansk Mountains, local glaciations are mainly controlled by moisture transport from the west across the Eurasian continent. Thus glaciations in the Verkhoyansk Mountains not only express local climate changes but also are strongly influenced by the extent of the Eurasian ice sheets.     

PGE mineralization and melt composition of chromitites in Proterozoic ophiolite complexes of Eastern Sayan,Southern Siberia

The Ospino-Kitoi and Kharanur ultrabasic massifs represent the northern and southern ophiolite branches respectively of the Upper Onot ophiolitic nappe and they are located in the southeastern part of the Eastern Sayan(SEPES ophiolites).Podiform chromitites with PGE mineralization occur as lensoid pods within dunites and rarely in harzburgites or serpentinized peridotites.The chromitites are classified into type I and type Ⅱ based on their Cr~#.Type I(Cr~# = 59-85) occurs in both northern and southern branches,whereas type Ⅱ(Cr~# = 76-90) occurs only in the northern branch.PGE contents range from ∑PGE 88-1189 ppb,Pt/Ir0.04-0.42 to ∑PGE 250-1700 ppb,Pt/Ir 0.03-0.25 for type I chromitites of the northern and southern branches respectively.The type Ⅱ chromitites of the northern branch have ∑PGE contents higher than that of type Ⅰ(468-8617 ppb,Pt/Ir 0.1-0.33).Parental melt compositions,in equilibrium with podiform chromitites,are in the range of boninitic melts and vary in Al_2O_3,TiO_2 and FeO/MgO contents from those of type I and type Ⅱ chromitites.Calculated melt compositions for type Ⅰ chromitites are(Al_2O_3)_(melt) = 10.6—13.5 wt.%,(TiO_2)_(melt) = 0.01-0.44 wt.%,(Fe/Mg)_(melt) = 0.42-1.81;those for type Ⅱ chromitites are:(Al_2O_3)_(melt) = 7.8-10.5 wt.%,(TiO_2)_(melt) = 0.01-0.25 wt.%,(Fe/Mg)_(melt) = 0.5-2.4.Chromitites are further divided into Os-Ir-Ru(Ⅰ) and Pt-Pd(Ⅱ) based on their PGE patterns.The type Ⅰ chromitites show only the Os-Ir-Ru pattern whereas type Ⅱ shows both Os-Ir-Ru and Pt-Pd patterns.PGE mineralization in type Ⅰ chromitites is represented by the Os-Ir-Ru system,whereas in type Ⅱ it is represented by the Os-Ir-Ru-Rh-Pt system.These results indicate that chromitites and PGE mineralization in the northern branch formed in a suprasubduction setting from a fluid-rich boninitic melt during active subduction.However,the chromitites and PGE mineralization of the southern branch could have formed in a spreading zone environment.Mantle peridotites have been exposed in the area with remnants of mantle-derived reduced fluids,as indicated by the occurrence of widespread highly carbonaceous graphitized ultrabasic rocks and serpentinites with up to 9.75 wt.%.Fluid inclusions in highly carbonaceous graphitized ultrabasic rocks contain CO,CO_2,CH4,N_2 and the δ~(13)C isotopic composition(-7.4 to-14.5‰) broadly corresponds to mantle carbon.     

The Late Paleozoic fold-thrust structure of the Tunka bald mountains, East Sayan (southern framing of the Siberian Platform)

According to the new geological, geochronological, and structural data, the Tunka bald mountains (East Sayan) have a nappe structure, which formed in the Late Carboniferous–Early Permian. The deformations have been dated by the ⁴⁰Ar–³⁹Ar method on the basis of syntectonic micas and amphiboles, whose structural and spatial positions have been determined in oriented thin sections. The geometrical analysis of macro- and microstructures has revealed three development stages of the structures, which followed one another in progressive deformation. The first (thrust-fault) stage (316–310 Ma) comprised a group of N-verging thrust sheets. In the second (fold deformation) stage (305–303 Ma), they were folded. The third (strike-slip fault) stage (286 Ma) comprised high-angle shears, along which V-shaped blocks were squeezed westward from the most compressed areas. All the structures developed under near-N–S-trending compression. The thrusting in the Tunka bald mountains was coeval with the major shear structures in the eastern Central Asian Fold Belt (Main Sayan Fault, Kurai, Northeastern, and Irtysh crumpled zones, etc.). Also, it was simultaneous with the formation of continental-margin calc-alkalic and shoshonite series (305–278 Ma) as well as that of the alkali and alkali-feldspar syenites and granites (281–278 Ma) of the Tarim mantle plume in the Angara–Vitim pluton, located near and east of the studied region. Thus, the simultaneous development of the Late Paleozoic structures, active-margin structures, and plume magmatism in southern Siberia might have resulted from the global geodynamic events caused by the interaction between the tectonic plates which formed the Central Asian Fold Belt.     

Sediment provenance of late Quaternary morainic,fluvial and loess‐like deposits in the southwestern Verkhoyansk Mountains (eastern Siberia) and implications for regional palaeoenvironmental reconstructions

A provenance analysis of late Quaternary deposits from tributaries of the Aldan and Lena rivers in Central Yakutia (eastern Siberia) was carried out using analysis of heavy minerals and clay mineralogy. Cluster analysis revealed one assemblage that is characterized by relatively high proportions of amphibole, orthopyroxene and garnet as well as pedogenic clay minerals, reflecting a sediment provenance from the wide catchment area of the Lena and Aldan rivers. In contrast, the three other clusters are dominated by stable heavy minerals with varying amounts of clinopyroxene, apatite and garnet, as well as high percentages of illite and chlorite that are indicative of source rocks of the Verkhoyansk Mountains. Glacial moraines reveal the local mountain source signal that is overprinted by the Lena‐Aldan signal in the oldest moraines by reworking processes. Alluvial sediments in the Verkhoyansk Foreland show a clear Lena source signal through intervals of the middle and late Pleistocene, related to a stream course closer to the mountains at that time. Loess‐like cover sediments are characterized by the dominant Lena provenance with increasing proportions of local mountain sources towards the mountain valleys. Aeolian sands in an alluvial terrace section at the mountain margin covering the time between 30 ka and 10 ka BP reflect temporarily dominant inputs of aeolian materials from the Lena Plains. Copyright © 2007 John Wiley & Sons, Ltd.     

The North of Eastern Siberia: Refuge of Mammoth Fauna in the Holocene

The global climate changings at the end of Pleistocene led to extinction of the typical representatives of Mammoth fauna–mammoth, woolly rhinoceros, wild horse, bison, muskox, cave lion, etc.–on the huge territories of Northern Eurasia. Undoubtedly the Mammoth fauna underwent pressure from the Upper Paleolithic Man, whose hunting activity also could play the role in decreasing the number of mammoths and other representatives of megafauna (large mammals). Archaeological data testify that the typical representatives of Mammoth fauna were the Man's hunting objects only till the end of the Pleistocene. Their bone remains are not usually found on the settlements of Mesolithic Man. Formerly it was supposed that the megafauna of ‘Mammoth complex’ was extinct by the beginning of Holocene. Nevertheless the latest data testify that the global extinction of the Mammoth fauna was sufficiently delayed in the north of Eastern Siberia. In the 1990s some radiocarbon data testified that the mammoths on the Wrangel Island existed for a long time during the Holocene from 8000 till 3700 y. BP. The present radiocarbon data show that wild horses inhabited the north of Eastern Siberia (the lower stream of the Enissey river, the Novosibirskie Islands, the East Siberian sea-shore) 3000–2000 y. BP. Musk-oxen lived on the Taimyr Peninsula and the Lena River delta about 3000 y. BP. Some bison remains from Eastern Siberia belong to the Holocene. The following circumstances could promote the process of preservation of the Mammoth fauna representatives. The cool and dry climate of this region promotes the maintenance of steppe associations – habitats of those mammals. The Late Paleolithic and Mesolithic settlements are not found in the Arctic zone of Eastern Siberia from the Taimyr Peninsula to a lower stream of the Yana River; they are very rare in the basins of the Indigirka and Kolyma Rivers. So, the small number of the Stone Age hunting tribes on the North of Eastern Siberia was another factor in the long-term preservation of some Mammoth fauna representatives.     

Geochemical and isotopic (Sr, U) variations of lake waters in the Ol’khon Region, Siberia, Russia: Origin and paleoenvironmental implications

The geochemical study of springs and lake waters from the Ol’khon Region, Siberia, confirms the strong chemical variability of these water samples, more particularly regarding their salinity. Such variability does not result from a simple mixing process between surface freshwaters and deeper saline waters. The variability, observed at the scale of a few square kilometers, would preferentially result from a secondary concentration processes (evaporation and/or cryogenesis) of lake waters of variable intensity from one lake to another. The U-disequilibria data suggest that the duration of the secondary process is certainly an important parameter to be considered to account for the variable salinity of these lakes. The data indicate that the lakes, however modest in size, could be as old as several ky, confirming therefore that the lake sedimentary deposits could represent relevant paleoenvironmental recorders for the last thousands years.     

Charcoal records from thermokarst deposits in central Yakutia, eastern Siberia: Implications for forest fire history and thermokarst development

Macroscopic charcoal records from a thermokarst lake deposit in central Yakutia, eastern Siberia, were used to reconstruct the history of forest fires and investigate its relationship to thermokarst initiation. High accumulation rates of charcoal and pollen were coincident in the basal deposits of the thermokarst lake, which suggests that both were initially deposited on the forest floor and subsequently reworked and accumulated in the thermokarst depression. High charcoal and pollen accumulation rates in the basal deposits, dating to 11,000-9000 cal yr BP, also indicate that the thermokarst topography developed during the early Holocene. A lower charcoal accumulation rate after ca. 9000 cal yr BP suggests that thermokarst development has been inhibited since this time. It also indicates that a surface-fire regime has been predominant at least since ca. 9000 cal yr BP in central Yakutia.     

PGE distribution in sulfide ores from ultramafic massifs of the central East Sayan Mountains,Southern Siberia,Russia

Data on the composition of sulfide ores from ultramafic massifs in the central East Sayan Mountains and on the regularities of platinum group elements (PGE) in these ores are presented. It is found that the highest PGE contents are characteristic for net-textured and massive ores from the Zhelos massif: total PGE content there is up to 15 ppm, with Pd/Pt = 3–8, for Ni and Cu contents of 1.5–2.8 and 0.5–2.7 wt%, respectively. In the disseminated ores of the Zhelos massif, PGE contents vary from 1 to 7 ppm, at Ni and Cu contents varying in the ranges of 0.5–1.0 and 0.2–0.4 wt %, respectively. In the Tokty-Oi massif, disseminated ores are characterized by higher absolute PGE contents (1.6 to 3.3 ppm) at similar Ni content. PGE tenor of disseminated ores is higher compared to that of massive and net-textured ones. In the cross-sections of both massifs, net-textured and massive ores of an essentially pyrrhotine composition are found at the contact between ultramafic and host rocks. Total PGE in these ores is up to 12 ppm. The obtained data on sulfur isotopes indicate the common, well-homogenized sources, and close physical–chemical depositional conditions of all ore types.     

Age of the Jombolok lava field (East Sayan): evidence from dendrochronology and radiocarbon dating

Dendrochronology and radiocarbon dating, with reference to remote sensing, digital elevation modeling, geological, and geomorphological data, provide new age constraints for the Jombolok lava field in the East Sayan Mountains (Siberia). The Jombolok lava field originated in the latest Late Pleistocene and underwent at least four phases of volcanic activity recorded in lava flows. Two earliest phases followed shortly one after another more than 13 kyr ago. The third phase corresponding to eruptions of Kropotkin volcano can be timed only relatively. The fourth phase has been dated by dendrochronology and AMS ¹⁴C of well-preserved wood buried under the youngest lava which occurs among older lavas near the Jombolok River mouth. The age of this activity is bracketed between the death of trees caused by eruptions 1268-928 years ago and the beginning of new tree growth on the surface of the most recent lavas 900 years ago.     

Chronology and Geochemistry of the Berezitovoe Polymetallic Gold Deposit in Eastern Siberia, Russia and its Geological Significance

The Berezitovoe deposit is a large-sized Au-Ag-Zn-Pb deposit in the east of the SelengaStanovoi superterrane, Russia. Au-Ag orebodies are hosted by tourmaline-garnet-quartz-muscovite metasomatic rocks; Zn-Pb orebodies are hosted by granodiorites, porphyritic granites and tourmalinegarnet-quartz-muscovite metasomatic rocks. These orebodies are surrounded by wall rocks dominated by the Tukuringra Complex granodiorites, porphyritic granites, and gneissic granodiorites. The alteration includes silicification and garnet, sericitization chloritization, carbonatization and kaollinization. LA-ICP-MS U-Pb zircon dating indicates that the gold mineralization can be divided into two stages in the Berezitovoe polymetallic gold deposit(at 363.5 ± 1.5 Ma, and133.4± 0.5).Hornblende-plagioclase gneisses of the Mogocha Group in the study area underwent Paleoproterozoic metamorphism(at 1870 ± 7.8 and 2400 ± 13 Ma), gneissic granodiorite of the Tukuringra Complex yields a late Paleozoic magmatic age(at 379.2 ± 1.1 Ma),and subalkaline porphyritic granitoid of the Amudzhikan Complex yield late Mesozoic magmatic ages(133-139 and 150-163 Ma). Granodiorites of the Tukuringra Complex in the study area have high concentrations of SiO_2(average of 60.9 wt%), are aluminum-oversaturated(average A/CNK of 1.49), are enriched in the large ion lithophile elements(e.g.,K, Rb, and Ba), U, Th, and Pb, are depleted in high field strength elements(e.g., Ta, Nb, and Ti), and have slightly negative Eu and no Ce anomalies in chondrite-normalized rare earth element diagrams.Fluid inclusions from quartz veins include three types: aqueous two-phase, CO_2-bearing three-phase,and pure CO_2. Aqueous two-phase inclusions homogenize at 167℃-249℃ and have salinities of 4.32%-9.47% NaCl equivalent, densities of 0.86-0.95 g/cm~3, and formed at depths of 0.52-0.94 km. In comparison, the C0_2-bearing three-phase inclusions have homogenization temperatures of 265℃-346℃,salinities of 7.14%-11.57% NaCl equivalent, and total densities of 0.62-0.67 g/cm~3. The geochemical and zircon U-Pb data and the regional tectonic evolution of the study area, show that the Berezitovoe polymetallic gold deposit formed in an island arc or active continental margin setting, most probably related to late Paleozoic subduction of Okhotsk Ocean crust beneath the Siberian Plate.     

The Taimyr fold belt, Arctic Siberia: timing of prefold remagnetisation and regional tectonics

Late Precambrian and Palaeozoic platform sediments from the Central–South Taimyr Peninsula (Arctic Siberia) are all remagnetised. The remagnetisation is prefold and is related to thermal remagnetisation caused by Taimyr Trap magmatism. The remagnetisation age is estimated to 220–230 Ma and, hence, is considerably younger than the ca. 251 Ma age for the main body of Siberian Trap flood basalts. The folding that affected the Taimyr region platform sediments also included the Taimyr “Traps,” hence, relegating Taimyr deformation to post-Mid Triassic time, and most probably, to a Late Triassic age. This shows that whilst thrusting terminated in the Urals during the Permian, crustal shortening continued in Taimyr, Novaya–Zemlya and the South Barents Sea, well into the Mesozoic.     

The Bazhenov Horizon of West Siberia: structure,correlation, and thickness

The type sections of the Bazhenov Horizon and formations recognized within this horizon have been identified based on a comprehensive analysis of paleontological, lithological, geophysical (well-log and CDP seismic data), and geochemical data on the West Siberian Basin. The Bazhenov Horizon was traced throughout the entire West Siberian sedimentary basin. The criteria for the recognition of the top and base of this horizon within the stratigraphic equivalents of the Bazhenov Formation were suggested. The proposed facies-stratigraphic zonation of the Bazhenov Horizon reflects the spatial location of all formations identified within this horizon. As seen on the newly proposed thickness map, the Bazhenov Horizon reaches a thickness of 15-25 m within the Bazhenov and Tutleim Formations, 30-35 m within the Mulym’ya Formation, 30-45 m within the Danilov Formation, 40-65 m within the Mar’yanovka Formation, up to 100 m within the Golchikha Formation, > 350 m within the Yanovstan Formation, up to 35 m within the Bagan Formation, and 35-40 m within the Maksimkin Yar Formation. A marginal filter (according to A.P. Lisitzin) has been identified along the East Siberian land.     

Long-Term Temperature Trends and Tree Growth in the Taymir Region of Northern Siberia

The northernmost conifers in the world are located well above the Arctic Circle in the Taymir region of northern Siberia and have been recording the thermal environment for centuries to millennia. The trees respond to temperatures beyond the narrow season of actual cambial cell division by means of root growth, photosynthesis, lignification of cell walls, and other biochemical processes. Data from annual tree-ring widths are used to reconstruct May–September mean temperatures for the past four centuries. These warm-season temperatures correlate with annual temperatures and indicate unusual warming in the 20th century. However, there is a loss of thermal response in ring widths since about 1970. Previously the warmer temperatures induced wider rings. Most major warming and cooling trends are in agreement with other high-latitude temperature reconstructions based on tree-ring analyses with some regional differences in timing of cooling in the late 18th century and of warming in the late 19th century.     

西伯利亚涅帕钾盐矿床地质,发展经过及其对我国找钾工作的启示

西伯利亚含盐盆地位于西伯利亚地台。含钾盐系属下寒武统安加拉组，岩盐层总厚６００余米，钾盐层厚７０－１５０ｍ，共有钾石盐岩和钾石盐－光卤石岩６层。钾石盐层中ＫＣｌ含量达３５％－４５％，Ｍｇｃｌ＿２和水不溶物含量均小于１％，含盐盆地四周以堡礁带和陆岛与广海相隔，含钾坳陷处于地台上坳陷最深部位。作者介绍了涅帕钾盐矿床的地质特征和形成条件，从钾盐预测－钾盐普查－发现钾盐矿床历经４０余年，在找钾工作中总结了大量的成功经验，对我国地质工作者如何寻找钾盐矿床是一种很好的启示。     

Dinocyst biostratigraphy of the Lower Cretaceous in North Siberia

The described scheme of the Lower Cretaceous (Berriasian-Barremian) stratigraphic subdivisions is elaborated based on palynological study of sections in the Khatanga depression, Ust-Yenisei region, Pur-Taz interfluve, and around the Ob River latitudinal segment, the North Siberia. Stratigraphic distribution of microphytoplankton studied in detail is used to distinguish 10 biostratigraphic units in the rank of dinocysts zones. Stratigraphic position of the zones is determined with confidence using data on the Lower Cretaceous reference sections in the Khatanga depression, which were principal ones by constructing the Boreal standard zonation. In majority, boundaries of the dinocysts beds are of a high correlation potential and can be regarded as reliable stratigraphic markers, as they are recognizable not only in Siberia, but also in northern Europe and America.     

The Maurynya section,West Siberia: a key section of the Jurassic-Cretaceous boundary deposits of shallow marine genesis

The Maurynya section exposed on the northwestern margin of West Siberia is one of few continuous sections of the Jurassic-Cretaceous boundary deposits in Boreal regions. In the meantime, it can be considered a reference section for the transitional Volgian-Ryazanian beds formed in shallow water environments of the West Siberian sea basin. This study is a synthesis of the new data with previous results of lithologic, paleontological, biostratigraphic, and (O, C, Sr) isotope studies of the Upper Volgian-lowermost Ryazanian of the Maurynya section. It has been established that the beginning of the Cretaceous (corresponding to the middle Late Volgian) is associated with a sharp increase in species number and diversity of cephalopods and bivalve mollusks on the northwestern margin of the West Siberian sea basin. This can be explained by an increase in its depths and their stabilization at a level which appeared optimal for the habitat of nekton, nektobenthos, and benthic fauna communities, superimposed on the general trend of warming. At the same time, the percentage of phytoplankton significantly increased, indicating the onset of transgression, which affected largely coastal landscapes and type of vegetation: The forests dominated by conifers were gradually succeeded by forests mostly composed of Ginkgoaceae.     

The Holocene environmental changes revealed from the sediments of the Yarkov sub-basin of Lake Chany,south-western Siberia

Lake Chany is the largest endorheic lake in Siberia whose catchment is entirely on the territory of Russia. Its geographical location on the climate-sensitive boundary of wet and dry landscapes provides an opportunity to gain more knowledge about environmental changes in the West Siberian interior during the Holocene and about the evolution of the lake itself. Sediment cores obtained from the Yarkov sub-basin of the lake in 2008 have been comprehensively studied by a number of approaches including sedimentology and AMS dating, pollen, diatom and chironomid analyses (with statistical interpretation of the results), mineralogy of authigenic minerals and geochemistry of plant lipids (biomarker analysis.). Synthesis of new results presented here and published data provides a good justification for our hypothesis that Lake Chany is very young, no older than 3.6 ka BP. Before that, between 9 and 3.6 ka BP, the Chany basin was a swampy landscape with a very low sedimentation rate; it could not be identified as a water body. In the early lake phase, between 3.6 and 1.5 ka BP, the lake was shallow, 1.2–3.5 m in depth, and it rose to its modern size, up to 6.5 m in depth, during the last millennium. Our data reveal important changes in the understanding of the history of this large endorheic lake, as before it was envisioned as a large lake with significant changes in water level since ca. 14 ka BP. In addition to hydrology, our proxies provide updates and details of the regional vegetation and climate change since ca. 4 ka BP in the West-Siberian forest-steppe and steppe. As evolution of the Chany basin is dependent on hydroclimatic changes in a large region of southern West Siberia, we compare lake-level change and climate-change proxies from the other recently and most comprehensively studied lakes of the region.     

Geochronology and paleomagnetism of mafic igneous rocks in the Olenek Uplift, northern Siberia: Implications for Mesoproterozoic supercontinents and paleogeography

We present a new, reliably dated Mesoproterozoic paleopole for Siberia, based on a combined geochronological and paleomagnetic study of mafic rocks within the Mesoproterozoic Sololi Group of the Olenek Uplift in northern Siberia. Ion microprobe (SHRIMP) U–Pb analysis yields crystallisation ages of 2036 ± 11 Ma for zircon from a basement granite and 1473 ± 24 Ma for baddeleyite from a large dolerite sill within the Kyutingde Formation. The baddeleyite result indicates that the lower Sololi Group is significantly older than was suggested by previous K–Ar results. Paleomagnetic analysis of the dolerite sill and related mafic intrusive rocks yields a paleopole at 33.6°N, 253.1°E, A₉₅ = 10.4°. A positive baked-contact test between the Kyutingde sill and sedimentary country rocks shows that the magnetisation is primary. Comparison of this paleopole with coeval results for Laurentia provides a revised reconstruction between Siberia and Laurentia, and implies that these two continents were parts of a single Mesoproterozoic supercontinent since at least 1473 Ma. We argue that Siberia, Laurentia, and Baltica belonged to the same supercontinent between 1473 Ma and mid-Neoproterozoic time.     

Holocene peat and carbon accumulation rates in the southern taiga of western Siberia

Although recent studies have recognized peatlands as a sink for atmospheric CO₂, little is known about the role of Siberian peatlands in the global carbon cycle. We have estimated the Holocene peat and carbon accumulation rate in the peatlands of the southern taiga and subtaiga zones of western Siberia. We explain the accumulation rates by calculating the average peat accumulation rate and the long-term apparent rate of carbon accumulation (LORCA) and by using the model of Clymo (1984, Philosophical Transactions of the Royal Society of London Series B 303, 605-654). At three key areas in the southern taiga and subtaiga zones we studied eight sites, at which the dry bulk density, ash content, and carbon content were measured every 10 cm. Age was established by radiocarbon dating. The average peat accumulation rate at the eight sites varied from 0.35 ± 0.03 to 1.13 ± 0.02 mm yr⁻¹ and the LORCA values of bogs and fens varied from 19.0 ± 1.1 to 69.0 ± 4.4 g C m⁻² yr⁻¹. The accumulation rates had different trends especially during the early Holocene, caused by variations in vegetation succession resulting in differences in peat and carbon accumulation rates. The indirect effects of climate change through local hydrology appeared to be more important than direct influences of changes in precipitation and temperature. River valley fens were more drained during wetter periods as a result of deeper river incision, while bogs became wetter. From our dry bulk density results and our age-depth profiles we conclude that compaction is negligible and decay was not a relevant factor for undrained peatlands. These results contribute to our understanding of the influence of peatlands on the global carbon cycle and their potential impact on global change.