scholarly journals Lake-Level fluctuations at Le Locle, Swiss Jura, from the Younger Dryas to the Mid-Holocene: A high-resolution record of climate oscillations during the final deglaciation

2002 ◽  
Vol 53 (2) ◽  
pp. 183-197 ◽  
Author(s):  
Michel Magny ◽  
Patrick Schoellammer
Keyword(s):  
High Resolution ◽  
Lake Level ◽  
Environmental Changes ◽  
Younger Dryas ◽  
Greenland Ice Sheet ◽  
Climate Oscillations ◽  
Lake Level Fluctuations ◽  
High Lake Level ◽  
Swiss Jura ◽  
Holocene Period

Abstract On the basis of a high-resolution (10 cm / 110 years) lacustrine sequence from Le Locle, Swiss Jura, a fine-scale pattern of palaeohydrological changes is reconstructed for the late Younger Dryas (YD) and the early to mid-Holocene period. The late YD is characterized by a general trend of a fall in lake level and a large climatic instability. The early to mid-Holocene period shows a quasi-cyclic pattern of lake-level fluctuations. Large drops in lake level occurred at ca. 11 600-10 200 cal. BP and ca. 8 900-7 700 cal. BP. Each was interrupted by a short-term rise in lake-level and followed by a longer phase of high lake level respectively at ca. 10 200-8 900 cal. BP and ca. 7 700-6 600 cal. BP. The high lake-level periods at le Locle appear to be in phase with cold spells reconstructed in central Europe, in eastern North America and in the Greenland ice-sheet, or with cooling events and salinity anomalies recorded in the North Atlantic zone. They also coincide with rising residual Δ14C values. These data and the Lateglacial oxygen-isotope GISP2 record suggest three successive quasi-cycles of climatic and environmental changes showing strong similarities in their internal structure. These cycles suggest that large-scale climate oscillations developing from the Bølling warming to the mid-Holocene could have been associated with changes in ocean ventilation probably induced by three deglaciation steps. Finally, as a working hypothesis, a re-exami- nation of the YD event is proposed from a Holocene point of view.

scholarly journals Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores

2010 ◽  
Vol 7 (11) ◽  
pp. 3531-3548 ◽  
Author(s):  
K. Lindhorst ◽  
H. Vogel ◽  
S. Krastel ◽  
B. Wagner ◽  
A. Hilgers ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Level ◽  
Lake Level ◽  
Sediment Cores ◽  
Lake Ohrid ◽  
Acoustic Data ◽  
Lake Level Fluctuations ◽  
Karst Lake ◽  
Multichannel Seismic Data ◽  
Mis 5

Abstract. Ancient Lake Ohrid is a steep-sided, oligotrophic, karst lake that was tectonically formed most likely within the Pliocene and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 60 m water depth. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during Marine Isotope Stage (MIS) 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly image several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water-filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

scholarly journals Paleohydrological Changes in Jura (France), and Climatic Oscillations around the North Atlantic from Allerød to Preboreal

2007 ◽  
Vol 49 (3) ◽  
pp. 401-408 ◽  
Author(s):  
Michel Magny
Keyword(s):  
Lake Level ◽  
Environmental Changes ◽  
Greenland Ice Sheet ◽  
Climatic Changes ◽  
Early Holocene ◽  
Oceanic Circulation ◽  
Cool Period ◽  
Climatic Oscillations ◽  
The North ◽  
Swiss Lake

ABSTRACTRegional palaeohydroiogical changes recorded in the Jura lakes, France, have led to a tentative reconstruction of a fine-scale pattern of climatic changes from Allerød to the early Holocene. The Younger Dryas (YD) can be subdivided into three parts: after a first wet phase, this cool period was characterized by increasing dryness; a short rise in lake level developed during its last part. Moreover, the YD was preceded and followed by two short rises in lake-level, which interrupted the lake-level lowerings developing during the Allerød and the Preboreal. Climatic oscillations reconstructed in Jura appear to be in phase with glacier and tree-limit movements in the Alps, with fluctuations in oxygen-isotope records from the Swiss lakes and the Greenland ice sheet, and with climatic oscillations recorded in the Norwegian Sea. Other correlations between (1) these climatic oscillations, (2)14C plateaux recorded in Swiss lake sequences, and (3) fluctuations in the residual ∆14C, support a correlation between regional palaeohydroiogical changes defined in Jura and broad-scale climatic oscillations; they also support the existence of a link between climatic changes in Western and Central Europe and oceanic circulation. Moreover, as working hypothesis, these correlations suggest high-precision timing for the climatic and environmental changes occurring during the early Holocene.

Quantitative Reconstruction of Younger Dryas to Mid-Holocene Paleoclimates at Le Locle, Swiss Jura, Using Pollen and Lake-Level Data

2001 ◽  
Vol 56 (2) ◽  
pp. 170-180 ◽  
Author(s):  
Michel Magny ◽  
Joël Guiot ◽  
Patrick Schoellammer
Keyword(s):  
Lake Level ◽  
General Pattern ◽  
Younger Dryas ◽  
Growing Season ◽  
Summer Temperature ◽  
Annual Precipitation ◽  
Climatic Parameters ◽  
Cold Event ◽  
Level Data ◽  
Swiss Jura

AbstractPollen and lake-level data from Le Locle in the Swiss Jura were used to quantitatively reconstruct climatic parameters for the Younger Dryas event and the first half of the Holocene period. The Younger Dryas cold event at Le Locle was characterized by (i) a general trend toward a slight increase in summer temperature and a decrease in annual precipitation and (ii) a marked drying phase at ca. 11,900 cal yr B.P. that occurred between two wetter ones. Further phases of major deficit in moisture occured at ca. 11,500 cal yr B.P. (Younger Dryas-Holocene transition), 10,800 cal yr B.P., 8700 cal yr B.P., and 6500 cal yr B.P. Climatic parameters reconstructed here suggest that phases of higher lake level developing at ca. 12,500–12,000, 11,750–11,600, 11,200–10,900 (synchronous with the Preboreal oscillation), 10,400–8900, 8400–8300 (possibly related to the 8200 yr event), and 7800–7000 cal yr B.P. coincided with an increase in annual precipitation, a decrease in summer temperature, and a shorter growing season. Conversely, periods of low lake level corresponded to a decrease in annual precipitation, an increase in summer temperature, and a longer growing season. This general pattern could have resulted from alternate southward-northward displacements of the Atlantic Westerly Jet.

Geomorphology of the lakebed and sediment deposition during the Holocene in Lake Visovac

2021 ◽  
Author(s):  
Nikolina Ilijanić ◽  
Slobodan Miko ◽  
Ozren Hasan ◽  
Dea Brunović ◽  
Martina Šparica Miko ◽  
...  
Keyword(s):  
High Resolution ◽  
Lake Sediment ◽  
National Park ◽  
Lake Level ◽  
Evolutionary Dynamics ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Depositional Environments ◽  
Lake Levels ◽  
The Holocene

<p>Lake Visovac is a tufa barrier lake on the Krka River between Roški slap (60 m asl) and Skradinski buk (46 m absl) waterfalls, included in the Krka national park as primarily unaltered area of exceptional natural value. Paleolimnological research was conceived to address a lake evolution and depositional environments through the geophysical survey and collection of the lake sediment cores. A high-resolution bathymetric map was obtained using a multibeam sonar. The average lake depth varies between 20 and 25 m. Sediment cores were investigated to extract physical properties, sedimentological, mineralogical, geochemical and paleoecological records constrained by the radiocarbon chronology, to understand what was happening to both the landscapes and lakescapes of Lake Visovac during the last 2.000 cal yr.</p><p>Significant findings of the project are geomorphological features on the lake bottom: submerged sinkholes of various sizes (up to 40 m deep); submerged tufa barriers in the area of Kalički kuk (southern part of Lake Visovac) at the depths of 15 and 17 m, followed by a series of buried cascade tufa barriers at the depth of 25 m covered with up to 10 m of Holocene lake sediments; submerged vertical tufa barrier up to 32 m-high near the mouth of Čikola River; submerged landslides, small (river) fan structures characterized by sediment waves. Ground-penetrating-radar (GPR) data have been acquired due to the presence of gas-saturated sediments over a large area of the lake, that limited the use of high-resolution acoustic profiling. A total thickness of sediments is up to 40 m. High resolution paleoenvironmental record through the Late Holocene gives evidence of high sedimentation rates in Lake Visovac, variable soil erosion impact on lake sediment composition and carbonate authigenic sedimentation. Higher organic carbon is observed in the last 50 years due to changes in land cover and reforestation. Pleistocene lake sediment outcrops occur up to 20 m above the present lake levels indicating higher lake levels as a consequence of higher elevation of tuffa barriers. Kalički kuk, which lies up to 20 m above present lake level, is a remnant of these barriers which have been dated to MIS5. Results allow us to interpret the environmental and evolutionary dynamics of Lake Visovac in the following way: lake level more than 20 m higher than today in mid-Pleistocene with significantly larger lake volume in Lake Visovac, with active Kalički kuk and Skradinski buk waterfalls; lower lake-level at the beginning of the Holocene when several small lakes existed in isolated basins in the area of Lake Visovac. The tufa barrier at Skradinski buk started to grow faster than the Kalički kuk barriers and waterfalls resulting in their flooding and submergence during the Holocene. The tufa barrier at Skradinski buk has grown 15 m since then. This study demonstrates the role of geomorphological lakebed characteristics in reshaping our understanding of the environmental changes and the future of Lake Visovac.</p><p>The research was conducted as part of the project funded by the Krka National Park and CSF funded QMAD project (IP-04-2019-8505).</p>

scholarly journals An investigation of rapid warm transitions during MIS2 and MIS3 using Greenland ice-core data and the CLIMBER-2 model

2002 ◽  
Vol 35 ◽  
pp. 398-402 ◽  
Author(s):  
Irene A. Mogensen ◽  
Sigfüs J. Johnsen ◽  
Andrey Ganopolski ◽  
Stefan Rahmstorf
Keyword(s):  
High Resolution ◽  
Time Scale ◽  
Ice Core ◽  
Ice Sheet ◽  
Younger Dryas ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Warm Climate ◽  
Model Simulations ◽  
Earth’S Climate

AbstractIn the search for abetter understanding of the dominant mechanisms of the Earth’s climate system, we present a study of rapid warm-climate transitions to Dansgaard– Oeschger events as seen in the ice cores from the Greenland ice sheet. We present a continuous δ18O record from the Greenland Icecore Project (GRIP) core with a resolution of 5 years until 50 kyr BP and of 20 years until 100 kyr BP. These data are compared with other high-resolution records, i.e. the Greenland Ice Sheet Project II (GISP2) chemistry record (25 years until 50 kyr BP) and the GRIP Ca2+ record (3 years until 100 kyr BP). All records have been transformed to the GISP2 Meese/Sowers time-scale. the high-resolution records are separated into interstadials and stadials, defined by the GRIP and GISP2 δ18O records. We examine in detail the transitions into the Dansgaard–Oeschger events, and propose a scenario for the changes that occur in the different ice-core records during the approximately 50 years the transition takes. Themain difference from previous studies is the much higher-resolution datasets available until 50 kyr BP; previous high-resolution studies by Taylor and others (1997) have focused on only the Younger Dryas/Preboreal transition. the data are compared to model simulations of the Dansgaard–Oeschger events performed with the CLIMBER-2 model of intermediate complexity (Petoukhov and others, 1998 ; Ganopolski and Rahmstorf, 2001).

scholarly journals Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores

2010 ◽  
Vol 7 (3) ◽  
pp. 3651-3689 ◽  
Author(s):  
K. Lindhorst ◽  
H. Vogel ◽  
S. Krastel ◽  
B. Wagner ◽  
A. Hilgers ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Level ◽  
Lake Level ◽  
Sediment Cores ◽  
Lake Ohrid ◽  
Acoustic Data ◽  
Lake Level Fluctuations ◽  
Karst Lake ◽  
Multichannel Seismic Data ◽  
Mis 5

Abstract. Ancient Lake Ohrid is a steep sided, oligotrophic, karst lake of likely Pliocene age and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 55 m. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during MIS 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly imaged several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

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