Younger Dryas-Preboreal Transition Research Articles

Stratigraphy of the Late Glacial and Holocene aeolian series in different sedimentary zones related to the Last Glacial maximum in Poland

Lateglacial and Holocene sandy aeolian sequences with palaeosol horizons located in different sedimentary zones in western-central Poland were analysed in order to establish their regional stratigraphical and palaeoenvironmental significance. Results of sedimentological, geomorphological and absolute dating methods from 3 representative profiles from an extraglacial zone (Leszczyca site), a glaciomarginal zone (Barczygłów site) and a glaciated zone (Godzięba site) are presented. A compilation of 31 luminescence dates from aeolian sands and 7 14C-dates from palaeosols formed the basement for establishing the stratigraphic position of the analysed deposits. The obtained results were correlated with reference to Greenland ice-core chronology, which has the best resolution for the Northern Hemisphere. In the extraglacial zone, aeolian deposition started in the Oldest Dryas and continued throughout the Older Dryas (main phase of dune built) with limited deposition in the Younger Dryas and finished in Preboreal. Aeolian deposition was interrupted by pedogenic processes in the Bølling and Allerød interstadials as well as in the Younger Dryas-Preboreal transition. Whereas in the glaciomarginal zone aeolian deposition started in the Younger Dryas and continued to the Early Boreal with a weakly expressed pedogenic process in the Early Preboreal. In the glaciated zone, aeolian deposition took place in the Younger Dryas. At the Barczygłów and Godzięba sites palaeosols of the Roman Period and 19th century were detected, covered by aeolian sands. The Subatlantic aeolian episodes were induced by human activity and registered forest fires. Identified periods of aeolian activity and pedogenic processes were correlated with other profiles from central and western Europe.

Early-Warning Signals for the Onsets of Greenland Interstadials and the Younger Dryas–Preboreal Transition

AbstractThe climate system approaches a tipping point if the prevailing climate state loses stability, making a transition to a different state possible. A result from the theory of randomly driven dynamical systems is that the reduced stability in the vicinity of a tipping point is accompanied by increasing fluctuation levels and longer correlation times (critical slowing down) and can in principle serve as early-warning signals of an upcoming tipping point. This study demonstrates that the high-frequency band of the δ18O variations in the North Greenland Ice Core Project displays fluctuation levels that increase as one approaches the onset of an interstadial (warm) period. Similar results are found for the locally estimated Hurst exponent for the high-frequency fluctuations, signaling longer correlation times. The observed slowing down is found to be even stronger in the Younger Dryas, suggesting that both the Younger Dryas–Preboreal transition and the onsets of the Greenland interstadials are preceded by decreasing stability of the climate state. It is also verified that the temperature fluctuations during the stadial periods can be approximately modeled as a scale-invariant persistent noise, which can be approximated as an aggregation of processes that respond to perturbations on certain characteristic time scales. The results are consistent with the hypothesis that both the onsets of the Greenland interstadials and the Younger Dryas–Preboreal transition are caused by tipping points in dynamical processes with characteristic time scales on the order of decades and that the variability of other processes on longer time scales masks the early-warning signatures in the δ18O signal.

The WAIS Divide deep ice core WD2014 chronology – Part 2: Annual-layer counting (0–31 ka BP)

Abstract. We present the WD2014 chronology for the upper part (0–2850 m; 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies. For the Holocene, the cosmogenic isotope records of 10Be from WAIS Divide and 14C for IntCal13 demonstrated that WD2014 was consistently accurate to better than 0.5 % of the age. For the glacial period, comparisons to the Hulu Cave chronology demonstrated that WD2014 had an accuracy of better than 1 % of the age at three abrupt climate change events between 27 and 31 ka. WD2014 has consistently younger ages than Greenland ice core chronologies during most of the Holocene. For the Younger Dryas–Preboreal transition (11.595 ka; 24 years younger) and the Bølling–Allerød Warming (14.621 ka; 7 years younger), WD2014 ages are within the combined uncertainties of the timescales. Given its high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high-quality proxies of volcanism, solar activity, atmospheric mineral dust, and atmospheric methane concentrations.

Socio-economic organization of Final Paleolithic societies: New perspectives from an aggregation site in Western France

Overlooked in larger European syntheses for some time, northwestern France now plays an important role in a dynamic research program investigating the very end of the Lateglacial in Western Europe. The discovery of the well-preserved open-air site of La Fosse has allowed for significant advances in our understanding of different aspects of the Younger Dryas-Holocene transition in this region. This homogenous lithic assemblage adds further precision to the Lateglacial chrono-cultural sequence and provides essential new information for investigating techno-economic changes that appeared during this period. A techno-functional study of the lithic material combined with a spatial analysis of artifact distribution provides insights concerning the site’s function. Several lines of evidence also shed light on occupation duration, activities carried out on-site, and the likely composition of the groups who occupied the site. The combination of the above lead us to interpret La Fosse as a large residential site. Following this, we propose a new mobility and land-use model for hunter-gatherer groups from the Younger Dryas-Preboreal transition in which La Fosse functioned as an aggregation site. This model confirms several previous hypotheses emphasizing the logistical character of mobility strategies of these societies. Finally, this scenario adds further details and precision concerning both the status and connections between different groups of sites within a complex socio-economic system.

Major earthquake at the Pleistocene-Holocene transition in Lake Vättern, southern Sweden

Lake Vattern, Sweden, is within a graben that formed through rifting along the boundary between two Precambrian terrains. Geophysical mapping and geological coring show that substantial tectonic movements along the Lake Vattern graben occurred at the very onset of the Holocene. This is evident from deformation structures in the soft sediment accumulated on the lake floor. Our interpretation of these structures suggests as much as 13 m of vertical tectonic displacements along sections of a >80-km-long fault system. If these large displacements are from one tectonic event, Lake Vattern must have had an earthquake with seismic moment magnitudes to 7.5. In addition, our geophysical mapping shows large landslides along sections of the steep lake shores. Pollen analysis of sediment infillings of some of the most prominent sediment deformation structures places this major seismic event at the Younger Dryas-Preboreal transition, ca. 11.5 ka. We suggest that this event is mainly related to the rapid release of ice-sheet load following the deglaciation. This paleoseismic event in Lake Vattern ranks among the larger known intraplate tectonic events in Scandinavia and attests to the significance of glacio-isostatic unloading.

Impact of relative sea level and rapid climate changes on the architecture and lithofacies of the Holocene Rhone subaqueous delta (Western Mediterranean Sea)

The modern Rhone delta in the Gulf of Lions (NW Mediterranean) is a typical wave-dominated delta that developed after the stabilization of relative sea level following the last deglacial sea-level rise. Similar to most other deltas worldwide, it displays several stacked parasequences and lobes that reflect the complex interaction between accommodation, sediment supply and autogenic processes on the architecture of a wave-dominated delta. The interpretation of a large set of newly acquired very high-resolution seismic and sedimentological data, well constrained by 14C dates, provides a refined three-dimensional image of the detailed architecture (seismic bounding surfaces, sedimentary facies) of the Rhone subaqueous delta, and allows us to propose a scenario for delta evolution during the last deglaciation and Holocene. The subaqueous delta consists of “parasequence-like” depositional wedges, a few metres to 20–30m in thickness. These wedges first back-stepped inland toward the NW in response to combined global sea-level rise and overall westward oceanic circulation, at a time when sediment supply could not keep pace with rapid absolute (eustatic) sea-level rise. At the Younger Dryas–Preboreal transition, more rapid sea-level rise led to the formation of a major flooding surface (equivalent to a wave ravinement surface). After stabilization of global sea level in the mid-Holocene, accommodation became the leading factor in controlling delta architecture. An eastward shift of depocentres occurred, probably favoured by higher subsidence rate within the thick Messinian Rhone valley fill. The transition between transgressive (backstepping geometry) and regressive (prograding geometry) (para)sequences resulted in creation of a Maximum Flooding Surface (MFS) that differs from a “classical” MFS described in the literature. It consists of a coarse-grained interval incorporating reworked shoreface material within a silty clay matrix. This distinct lithofacies results from condensation/erosion, which appears as an important process even within supply-dominated deltaic systems, due to avulsion of distributaries. The age of the MFS varies along-strike between ca. 7.8 and 5.6kyrcal. BP in relation to the position of depocentres and climatically-controlled sediment supply. The last rapid climate change of the Holocene, the Little Ice Age (1250–1850AD), had a distinct stratigraphic influence on the architecture and lithofacies of the Rhone subaqueous delta through the progradation of two deltaic lobes. In response to changes in sediment supply linked to rapid climate changes (and to anthropic factors), the Rhone delta evolved from wave-dominated to fluvial dominated, and then wave dominated again.

La fin du Tardiglaciaire dans le Grand-Ouest de la France

In recent years, the Late Glacial period of Western France has been the scene of exciting new research. Prior to this research, the human occupation of Western France at the very end of the Pleistocene was seldom considered in discussions of European Prehistory. The presence of few stratified sites and the acidic soils of the Armorican Massif, which preserve few organic remains, are probably to blame for this treatment. A systematic study of assemblages collected in the 1970s-80s and the excavation of new sites allow us to re-examine the Final Palaeolithic of Western France. This new research has allowed us to propose a new chrono-cultural organization of the lithic industries. Because few sites are well-dated or stratified in Western France, this new chronology is based on lithic technology and a comparison of assemblages from the surrounding areas. In this paper, I specifically deal with assemblages long thought to be Magdalenian. However, some are in fact younger and represent a different technology that was replaced at the very end of the Late Glacial, during the Younger Dryas-Preboreal transition. These so-called ’ Post-Azilian’ industries mark a clear technical departure from the Azilian that preceded and the early Mesolithic that succeeded them. Contrary to the Azilian, where non-uniform elongated flakes were the main objective, blades and bladelettes are the central focus of reduction in post-Azilian societies. Post-Azilian blanks are regular and standardized. They are produced from methods using high-quality raw materials. The bladelettes are used to make different kinds of projectile points. The design of projectiles varies across Europe and these different types are seen as the cultural markers of separate traditions : Laborian/ Epilaborian, Ahrensburgian/ Epiahrensburgian, Swiderian,… The assemblages of Western France show an interesting diversity of projectile points. Straight backed points are most common. These projectile points testify to southern influences and are characteristic of the Epilaborian in Southern France. The presence of these projectile points in Western France is not surprising considering the fact they have been found in surrounding areas ; it is however unexpected to find elements similar to the Ahrensburgian and Epiahrensburgian. The presence of Ahrensburgian tanged points and oblique truncated points in Western France show the extension of these Northern European traditions farther West. While these axial points are the most common, our work also suggests the existence of trapezoidal elements probably used as cutting points. Well known during the second half of the Mesolithic and the Neolithic, this kind of projectile point seems to appear much earlier than usually considered. We are currently working on the origin of this concept (changes in hunting strategies, diversification of targets) and its link with the environmental changes of the end of the Pleistocene. While projectile point types vary throughout Europe, study of the lithic sub-system shows the diffusion of strong technical concepts over a wide area. The assemblages of these different European traditions testify to the presence of homogeneous objectives and methods of production. This homogeneity suggests that there may be a large European techno-complex composed of several traditions that are not necessarily contemporaneous or geographically restricted. This new view of the very end of the Late Glacial period allows us to develop new hypotheses about the socio-economic organization of these human societies. From this perspective it is interesting to consider the impact climatic instability may have had on populations during this period.

The Holocene palaeoenvironmental changes reflected in the multi-proxy studies of Lake Słone sediments (SE Poland)

Multi-proxy data from the Lake Słone sediments (SE Poland) yielded information on the Holocene changes of Lake Słone in a karst region. Changes of limnological conditions and vegetation reconstructions correspond to high resolution multi-proxy records from north-central Europe. Ostracods showed several small oscillations. Most significant changes occurred at 12300cal yr BP (Younger Dryas–Preboreal transition) and between 11800 and 11100cal yr BP (“Preboreal Oscillation”). Lowering of the water table at around 11100–10800cal yr BP was probably connected with abrupt warming at ca. 11000cal BP. Temperature and water depth fell at about 8400–8100cal yr BP (8200cal yr BP). The Atlantic period was generally warm and is divided into two parts: an older one with comparatively stable water level and a second one (between 7000 and 6300cal yr BP) with two phases of higher water level separated by lowering at 6800cal yr BP. At the transition from the Atlantic to the Subboreal (6200–5950cal yr BP) the dry period is more pronounced than changes in the second half of the Atlantic. Since the beginning of the Subboreal an increase in human activity in Central Europe was the main factor shaping the landscape and changing the limnic regimes.

High frequency climate variability of the Norwegian Atlantic Current during the early Holocene period and a possible connection to the Gleissberg cycle

A high-resolution sediment core (MD95-2011) from the Vøring Plateau has been studied to document the variability of the surface water conditions during the Younger Dryas—Preboreal (13—9 kyr BP) in the eastern Norwegian Sea, in order to assess the climate variability in a period considered to be highly dynamic. Quantitative summer sea surface temperatures (SSSTs) with a time resolution of 20—40 years are reconstructed using three different diatom transfer function methods. The Younger Dryas—Preboreal transition at site MD95-2011 is documented with a temperature increase of 3.5°C/3°C within 100 years. Following, the record resolves for the first time PBO as two prominent cooling events centred at 11.2 and 11.3 kyr BP. In addition, a broad cooling event documented from 10.3—9.9 kyr BP coincides with previously documented climatic events as the 10.3 event and Erdalen Event 1 (10.1—9.9 kyr BP) and 2 (~9.7 kyr BP), respectively. Constrained by the observed SSST changes and diatom assemblages, short-term SSST changes with a periodicity of 80—120 years are observed, and the length of this period might indicate a possible connection to the solar Gleissberg cycle. The North Atlantic heat transport is highly sensitive to freshwater inputs, and the interplay of freshwater forcing with insolation forcing is considered as the controlling mechanism of climate changes at site MD05-2011 during the early Holocene. However, the century-scale variability of 80—120 years cannot explain the large-scale variability during the early Holocene, but is of importance for understanding the underlying small-scale oscillations.

Variations in temperature and extent of Atlantic Water in the northern North Atlantic during the Holocene

We compare six high-resolution Holocene, sediment cores along a S–N transect on the Norwegian–Svalbard continental margin from ca 60°N to 77.4°N, northern North Atlantic. Planktonic foraminifera in the cores were investigated to show the changes in upper surface and subsurface water mass distribution and properties, including summer sea-surface temperatures (SST). The cores are located below the axis of the Norwegian Current and the West Spitsbergen Current, which today transport warm Atlantic Water to the Arctic. Sediment accumulation rates are generally high at all the core sites, allowing for a temporal resolution of 10–102 years. SST is reconstructed using different types of transfer functions, resulting in very similar SST trends, with deviations of no more than ±1.0/1.5°C. A transfer function based on the maximum likelihood statistical approach is found to be most relevant. The reconstruction documents an abrupt change in planktonic foraminiferal faunal composition and an associated warming at the Younger Dryas–Preboreal transition. The earliest part of the Holocene was characterized by large temperature variability, including the Preboreal Oscillations and the 8.2k event. In general, the early Holocene was characterized by SSTs similar to those of today in the south and warmer than today in the north, and a smaller S–N temperature gradient (0.23°C/°N) compared to the present temperature gradient (0.46°C/°N). The southern proxy records (60–69°N) were more strongly influenced by slightly cooler subsurface water probably due to the seasonality of the orbital forcing and increased stratification due to freshening. The northern records (72–77.4°N) display a millennial-scale change associated with reduced insolation and a gradual weakening of the North Atlantic thermohaline circulation (THC). The observed northwards amplification of the early Holocene warming is comparable to the pattern of recent global warming and future climate modelling, which predicts greater warming at higher latitudes. The overall trend during mid and late Holocene was a cooling in the north, stable or weak warming in the south, and a maximum S–N SST gradient of ca 0.7°C/°N at 5000cal. years BP. Superimposed on this trend were several abrupt temperature shifts. Four of these shifts, dated to 9000–8000, 5500–3000 and 1000 and ∼400cal. years BP, appear to be global, as they correlate with periods of global climate change. In general, there is a good correlation between the northern North Atlantic temperature records and climate records from Norway and Svalbard.

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

Upon closer inspection, the classical view of the synchronous relationship between tropospheric methane mixing ratio and Greenland temperature observed in ice samples reveals clearly discernable variations in the magnitude of this response during the Late Pleistocene (<50kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10kyr BP. The delta13CH4 and deltaD-CH4 of tropospheric methane recorded in ice samples provide a useful constraint on the palaeomethane budget estimations. Anticipated changes in palaeoenvironmental conditions are recorded as changes in the isotope signals of the methane precursors, which are then translated into past global delta13CH4 and deltaD-CH4 signatures. We present the first methane budgets for the late glacial period that are constrained by dual stable isotopes. The overall isotope variations indicate that the Younger Dryas (YD) and Preindustrial Holocene have methane that is 13C- and 2H-enriched, relative to Modern. The shift is small for delta13CH4 (approx. 1 per thousand) but greater for deltaD-CH4 (approx. 9 per thousand). The YD delta13CH4-deltaD-CH4 record shows a remarkable relationship between them from 12.15 to 11.52kyr BP. The corresponding C- and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This delta13CH4-deltaD-CH4 relationship breaks down during the YD-Preboreal transition. In both age cases, catastrophic releases of hydrates with Archaeal isotope signatures can be ruled out. Thermogenic clathrate releases are possible during the YD period, but so are conventional natural gas seepages.

The long-term succession of cladoceran fauna and palaeoclimate forcing: A 14,600-year record from Plešné Lake, the Bohemian Forest

A sediment record of cladoceran remains was analysed in a 543 cm long core from Plesne jezero (Plesne Lake), the Bohemian Forest, Czech Republic. The core covered the time period from the Oldest Dryas to the present. Littoral and benthic Cladocera included 11 species of the family Chydoridae while three species (Bosmina longispina, Daphnia cf. pulicaria and D. cf. longispina) lived in the open water. Remains of Alona quadrangularis and Chydrous sphaericus occurred in the oldest sediment layers from the beginning of the Bolling chronozone. Bosmina longispina and Daphnia cf. pulicaria appeared about 400 years later. Inorganic sediment accumulated at a relatively high rate of ∼ 90 mg cm−2 yr−1 at that time, diluting cladoceran remains and organic matter. Remains of Cladocera accumulated at 0.1 to 0.01 of the Holocene rate, making it difficult to observe effects of climate variation on the species structure of Cladocera in the Late-Glacial. Production of remains increased after warming during the Younger Dryas-Preboreal transition at ∼11.6 kyr BP, and the proportion of littoral species increased. The most important change in cladoceran fauna occurred at ∼10.5 kyr BP and culminated with afforestation of the catchment around 10.3 kyr BP. The domaination of Bosmina longispina lasted for ∼250 years. The afforestation occurred concurrently with a decrease in lake water pH. Bosmina longispina and Daphnia cf. pulicaria disappeared, production of cladoceran remains decreased, but biodiversity increased. Planktonic Cladocera were represented by Daphnia cf. longispina during most of the rest of the Holocene. The production of Cladocera never reached the Preboreal level. Since ∼ 5 cal. kyr BP, the inferred pH continuously decreased. The final decline was likely caused by cooling during the Little Ice Age and by sulphur emissions from ore smelting. The recent acidification of lake water and impoverishment of aquatic fauna was brought about by emissions of sulphur and nitrogen compounds in the 20th century.

The Preboreal climate reversal and a subsequent solar‐forced climate shift

AbstractAccurate chronologies are essential for linking palaeoclimate archives. Carbon‐14 wiggle‐match dating was used to produce an accurate chronology for part of an early Holocene peat sequence from the Borchert (The Netherlands). Following the Younger Dryas–Preboreal transition, two climatic shifts could be inferred. Around 11 400 cal. yr BP the expansion of birch (Betula) forest was interrupted by a dry continental phase with dominantly open grassland vegetation, coeval with the PBO (Preboreal Oscillation), as observed in the GRIP ice core. At 11 250 cal. yr BP a sudden shift to a humid climate occurred. This second change appears to be contemporaneous with: (i) a sharp increase of atmospheric 14C; (ii) a temporary decline of atmospheric CO2; and (iii) an increase in the GRIP 10Be flux. The close correspondence with excursions of cosmogenic nuclides points to a decline in solar activity, which may have forced the changes in climate and vegetation at around 11 250 cal. yr BP. Copyright © 2004 John Wiley &amp; Sons, Ltd.

The 12,460-Year Hohenheim Oak and Pine Tree-Ring Chronology from Central Europe—A Unique Annual Record for Radiocarbon Calibration and Paleoenvironment Reconstructions

The combined oak and pine tree-ring chronologies of Hohenheim University are the backbone of the Holocene radiocarbon calibration for central Europe. Here, we present the revised Holocene oak chronology (HOC) and the Preboreal pine chronology (PPC) with respect to revisions, critical links, and extensions. Since 1998, the HOC has been strengthened by new trees starting at 10,429 BP (8480 BC). Oaks affected by cockchafer have been identified and discarded from the chronology. The formerly floating PPC has been cross-matched dendrochronologically to the absolutely dated oak chronology, which revealed a difference of only 8 yr to the published 14C wiggle-match position used for IntCal98. The 2 parts of the PPC, which were linked tentatively at 11,250 BP, have been revised and strengthened by new trees, which enabled us to link both parts of the PPC dendrochronologically. Including the 8-yr shift of the oak-pine link, the older part of the PPC (pre-11,250 BP) needs to be shifted 70 yr to older ages with respect to the published data (Spurk 1998). The southern German part of the PPC now covers 2103 yr from 11,993–9891 BP (10,044–7942 BC). In addition, the PPC was extended significantly by new pine chronologies from other regions. A pine chronology from Avenches and Zürich, Switzerland, and another from the Younger Dryas forest of Cottbus, eastern Germany, could be crossdated and dendrochronologically matched to the PPC. The absolutely dated tree-ring chronology now extends back to 12,410 cal BP (10,461 BC). Therefore, the tree-ring-based 14C calibration now reaches back into the Central Younger Dryas. With respect to the Younger Dryas-Preboreal transition identified in the ring width of our pines at 11,590 BP, the absolute tree-ring chronology now covers the entire Holocene and 820 yr of the Younger Dryas.

Younger Dryas–Preboreal transition documented in the fluvial environment of Polish rivers

The rapid climatic change at the Younger Dryas–Preboreal transition has been documented in the sequence of annually laminated sediments of Lake Gościąż in the middle course of the Vistula Valley. The author correlates this key profile with about 50 localities of alluvial sediments and abandoned channels in the Vistula and Warta catchments. Discussed deposits have been radiocarbon-dated. The interpretation is supported by pollen diagrams. It is concluded that in most cases, either abundance of large paleochannels or a change from channel to overbank facies or to organic sedimentation took place just at the transition time. Also, in the fills of the Late glacial paleochannels, a decline in fluvial activity is observed that is evidenced by a change in grain size composition. However, an exact dating of this rapid transition is difficult as it coincides with the radiocarbon plateau at 10 ka BP.

Change in the frequency of extreme events as the indicator of climatic change in the Holocene (in fluvial systems)

The transformation of natural systems of climatic origin in the Holocene may be realised by a change in the type of extreme events, or by a change in their frequency, or by both. The rapid warming at the Younger Dryas–Preboreal transition exemplifies a parallel drop in frequency and a change in the type of events. Several wetter phases of the Holocene are characterised by rises in frequency of various types of extreme rainfalls. The fragmentary records of events in the fluvial and slope systems coincide with smoothed variations in stable ecosystems and shifts of ecotonal zones (such as tree line and lake levels).

Seismostratigraphy and sediment studies of Lake Hestvatn, southern Iceland: implications for the deglacial history of the region

AbstractCore 95‐HV was obtained from Lake Hestvatn, southern Iceland, after a seismic survey had identified a sediment sequence over 45 m thick in the lake. The core penetrated ca. 25 m into the sediment correlating with seismostratigraphic unit 2 of alternating seismic facies, with semi‐parallel reflectors of high amplitude and chaotic reflectors. Detailed sedimentological, chemical, magnetic and chronostratigraphical analyses on core 95‐HV, combined with interpretation of the seismic survey, show considerable changes in the sedimentary environment between ca. 10300 and 9000 14C yr BP (reservoir corrected). The lowermost ca. 12 m of the core was deposited in a marine environment during energy shifts from a very rapid accumulation of sandy turbidite units to slower deposition of suspended fine‐grained sediments. The turbidite units, thought to have originated from catastrophic outburst floods (jökulhlaup), contributed greatly to the high sediment accumulation rate at the Younger Dryas–Preboreal transition. Further change in the sedimentary environments is evidenced by the deposition of organic‐rich lake sediment with abundant tephra layers, starting at ca. 9000 yr BP (seismostratigraphic unit 3). The study shows that the inland glacier did not override the site of Hestvatn during the time of sediment deposition in the lake basin. Copyright © 2001 John Wiley &amp; Sons, Ltd.

Early Preboreal cooling in the Nordic seas region triggered by meltwater

Research Article| July 01, 1998 Early Preboreal cooling in the Nordic seas region triggered by meltwater Morten Hald; Morten Hald 1University of Tromsø, Department of Geology, N-9037 Tromsø, Norway Search for other works by this author on: GSW Google Scholar Sveinung Hagen Sveinung Hagen 1University of Tromsø, Department of Geology, N-9037 Tromsø, Norway Search for other works by this author on: GSW Google Scholar Author and Article Information Morten Hald 1University of Tromsø, Department of Geology, N-9037 Tromsø, Norway Sveinung Hagen 1University of Tromsø, Department of Geology, N-9037 Tromsø, Norway Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1998) 26 (7): 615–618. https://doi.org/10.1130/0091-7613(1998)026<0615:EPCITN>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Morten Hald, Sveinung Hagen; Early Preboreal cooling in the Nordic seas region triggered by meltwater. Geology 1998;; 26 (7): 615–618. doi: https://doi.org/10.1130/0091-7613(1998)026<0615:EPCITN>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract At the Younger Dryas–Preboreal transition, a high-resolution core from the northeastern Norwegian Sea reveals a two-step warming of sea surface temperatures dated at respectively 10 200–10 000 and 9700–9500 14C yr B.P. (11 450–11 350 and 11 150–11 000 cal. yr B.P.). Warming was interrupted by a period having stable temperatures and a reduction in sea surface salinity, and we suggest that this pause in warming was triggered by an increase in freshwater supply that may have hampered the North Atlantic heat conveyor. The freshwater influx correlates to an atmospheric cooling over both the Greenland ice sheet and northwest Europe and to cooling of surface temperatures in the Nordic seas. Freshwater may have been supplied from the waning Fennoscandian ice sheet. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Environmental changes at the Younger Dryas-Preboreal transition and during the early Holocene: some distinctive aspects in central Europe

Data on environmental change at the Younger Dryas-Preboreal transition and during the early Holocene are reviewed with particular reference to evidence from Poland and neighbouring areas of central Europe. Various factors modified the rate of environmental change during the general warming and reforestation. The preservation in central Europe of coniferous forest at the beginning of the Holocene, and the relatively late development of deciduous forest, were connected with the continuation of a continental climate until 9000-8500 BP. This is the main cause for a distinct division of the early Holocene into three phases: 1) 10 300-9500 BP; rapid warming, 2) Preboreal-Boreal continuous transformation 10 000-8500 BP; 3) change to oceanic climate 8700-7700 BP. During the 'Eoholocene' period, the various environmental systems - such as biological, aeolian, fluvial and lacustrine-exhibited diachronous evolution with different rates of change. The distinctive changes in central Europe are contrasted with other regions in the north-south European transect, taking into account such factors as substrate differences, plant migration rates and the pattern of deglaciation.