Palynology of the Last Interglacial-Glacial Cycle in Midlatitudes of Southern Chile

1981 ◽  
Vol 16 (3) ◽  
pp. 293-321 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Primary Component ◽  
Southern Chile ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
The Holocene ◽  
Westerly Winds ◽  
Pollen And Spores ◽  
Components Analysis ◽  
Age Relations ◽  
Nothofagus Dombeyi

AbstractPollen and spores in stratigraphic sections located between 40 and 42°S range in age from the Holocene, through much of the Llanquihue Glaciation, to the last interglaciation. Chronology of the stratigraphy derives from some 35 14C ages and the age relations of Llanquihue Drift and related deposits. Q-Mode, rotated, principal-components analysis of four key pollen records covering the last interglacial-glacial cycle resulted in four leading components: Nothofagus dombeyi type, Gramineae, Weinmannia-Fitzroya type, and Myrtaceae. Analysis emphasizes interaction between the first two components. Loadings of Gramineae during the interglaciation are high, unlike the Holocene; Weinmannia-Fitzroya-type loadings, prominent in the Holocene, are negligible during the interglaciation. N. dombeyi type is the primary component during Llanquihue Glaciation; it becomes modified by increases of Gramineae sometime after 31,000 and before 14,000 yr B.P. and of Myrtaceae later. The Myrtaceae with Weinmannia-Fitzroya type also registers some activity around 42,000 yr B.P. Fluctuations in the belt of westerly winds, reflecting changing meteorological conditions in polar latitudes, are suggested by these data. With the belt located farther south than it is today, interglacial climate was much drier and warmer than during the Holocene; more northerly displacement of the belt obtained when climate was colder during Llanquihue Glaciation. Evidence from comparable latitudes in the Southern Hemisphere points toward a synchrony of major climatic events indicating harmonious fluctuations in the position of the westerlies.

scholarly journals QUATERNARY SOIL-GEOLOGICAL STRATIGRAPHY IN GREECE

2018 ◽  
Vol 36 (2) ◽  
pp. 856 ◽  
Author(s):  
R. Paepe ◽  
I. Mariolakos ◽  
E. Van Overloop ◽  
S. Nassopoulou ◽  
J. Hus ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Ice Age ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Middle Term ◽  
Tropical Regions ◽  
The Holocene ◽  
Of Greece

Peloponnesus and Crete are probably offering the best possible standard sections for Eastern Mediterranean Pleistocene Series. Complete Pleistocene Standard Lithostratigraphic Sections from Sparta (Peloponnesus) and Kandanos (Crete) reveal continuous Pleistocene Land Sequences composed of cyclic palaeosol levels interfering with clastic fluvial, eolian (loess) and gravel deposits comparable with analogues found elswhere over the earth. Most suitable for correlation are: a) the standard Idfess area of Northern Europe, Russia and China, and b) the subtropical and tropical regions of Africa and Asia. The standard Greek Pleistocene Lithostratigraphic Sequence independently recorded at both sites (and partially from sites in other regions of Greece) reveal a number of 103 palaeosols of both interglacial and interstadial stages, indicating the extreme warm to relative warm phases of the Pleistocene ice age. This number suits surprisingly well to the 103 levels of the equally warm odd numbered oxygen isotopie stages (OIS) of the Pleistocene deep sea record which equally encompass the warm phases of the Pleistocene. Special attention is given to the Upper Pleistocene of Koroni (Southern Peloponnesus) as a case study for the Last Interglacial - Last Glacial Cycle, i.e. the middle term cycle extending in time from 127 Ka (thousand years) till 10 Ka or beginning of the Holocene. It stands as a model for the recurrent 100 Ka cycles of the long term overall Pleistocene record. Finally, in addition to the Pleistocene, the twenty wet - dry cycles of the Holocene are reviewed.

scholarly journals Climate changes in interior semi-arid Spain from the last interglacial to the late Holocene

2019 ◽  
Author(s):  
Dongyang Wei ◽  
Penélope González-Sampériz ◽  
Graciela Gil-Romera ◽  
Sandy P. Harrison ◽  
I. Colin Prentice
Keyword(s):  
Late Holocene ◽  
Potential Evapotranspiration ◽  
Weighted Averaging ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Pronounced Increase ◽  
The Holocene ◽  
Western Mediterranean Basin ◽  
Summer Warming ◽  
Temperature Seasonality

Abstract. The El Cañizar de Villarquemado sequence provides a palaeoenvironmental record from the western Mediterranean Basin spanning the interval from the last part of MIS6 to the late Holocene. The pollen and sedimentological records provide qualitative information about changes in temperature seasonality and moisture conditions. We use Weighted Averaging Partial Least-Squares (WA-PLS) regression to derive quantitative reconstructions of winter and summer temperature regimes from the pollen data, expressed in terms of the mean temperature of the coldest month (MTCO) and growing degree days above a baseline of 0 °C (GDD0) respectively. We also reconstruct a moisture index (MI), the ratio of annual precipitation to annual potential evapotranspiration, taking account of the effect of low CO2 on water use efficiency. We find a rapid summer warming at the transition to MIS5. Summers were cold during MIS4 and MIS2, but some intervals in MIS3 were characterized by summers as warm as the warmest phases of MIS5 or the Holocene. However, MIS3 was not significantly warmer in winter than other intervals, and there was a gradual decline in winter temperature from MIS4 through MIS3 to MIS2. The pronounced changes in temperature seasonality during MIS5 and MIS1 are consistent with changes in summer insolation. The ecophysiological effects of changing CO2 concentration through the glacial cycle has a significant impact on reconstructed MI. Conditions became progressively more humid during MIS5 and MIS4 was also relatively humid, while MIS3 was more arid. High MI values are reconstructed during the deglaciation and there was a pronounced increase in aridity during the Holocene. Changes in MI are anti-correlated with changes in GDD0, with increased MI during intervals of summer warming indicating a strong influence of temperature on evapotranspiration. Although our main focus here is on longterm changes in climate, the Villarquemado record also shows millennial-scale changes corresponding to Dansgaard-Oeschger cycles.

Warm Climate States during Last Glacial Cycle with a Multi-Resolution Climate/Ice Sheet Model

2020 ◽  
Author(s):  
Paul Gierz ◽  
Lars Ackermann ◽  
Christian Rodehacke ◽  
Uta Krebs-Kanzow ◽  
Christian Stepanek ◽  
...  
Keyword(s):  
Climate Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Sea Levels ◽  
The Holocene ◽  
Climate Model Simulations ◽  
Proxy Reconstructions ◽  
Improved Model

<p>Interglacials during the Quaternary represent the youngest climate states in the paleoclimate record that are similar to potential warmer-than-present states during the Anthropocene. In particular, those periods with warmer reconstructed temperatures and/or higher sea levels provide insights into the mechanisms that may be at work now and in the future. To date, climate model simulations of Quaternary Interglacials have been restricted to Atmosphere-Biosphere-Ocean simulations, with static ice sheet geometries from glaciological, geological, and geophysical reconstructions. Simulations including fully interactive ice sheets have not been widely available. Here, we present the first simulations of the PMIP4 timeslices for the Holocene and the Last Interglacial (LIG) with a fully coupled multi-resolution climate/cryosphere model, the AWI-ESM. We compare the simulated snapshots for the Holocene and LIG to simulations to proxy reconstructions, and to runs without dynamic ice sheets to highlight the processes now represented by the improved model. Furthermore, we show various schemes implemented in our model system to represent the ice sheet mass balance, both from surface ablation as well as ocean interaction. We find that both the Holocene and Last Interglacial ice sheets contain a smaller volume of ice compared to present day, with relative sea level equivalent changes of -3% and -7%, respectively.</p>

Seasonal origin of the thermal maxima at the Holocene and the last interglacial

Nature ◽  
2021 ◽  
Vol 589 (7843) ◽  
pp. 548-553
Author(s):  
Samantha Bova ◽  
Yair Rosenthal ◽  
Zhengyu Liu ◽  
Shital P. Godad ◽  
Mi Yan
Keyword(s):  
Last Interglacial ◽  
The Holocene

Last interglacial environment of the Baikal Region (Southern Siberia, Russia) based on analysis of fossil invertebrates and plants

2021 ◽  
Vol 4 (6) ◽  
Author(s):  
S.A. KUZMINA ◽  
L.A. SAVELIEVA ◽  
S.S. POPOVA ◽  
F.E. MAKSIMOV ◽  
V.YU. KUZNETSOV ◽  
...  
Keyword(s):  
Baikal Region ◽  
Plant Macrofossils ◽  
Fossil Insects ◽  
Last Interglacial ◽  
Southern Siberia ◽  
Lower Unit ◽  
Wide Range ◽  
Pollen And Spores ◽  
Reference Section ◽  
Moderate Climate

New data on fossil insects, soil and freshwater invertebrates, plant macrofossils, pollen and spores were obtained from a problematic lower unit of the reference section Bely Yar-II (Tunka Rift, Baikal Region, Russia). The invertebrates show a natural succession from a small lake to a wetland; plant macrofossils confirm the early stages of succession. Pollen and spore data reflect a wide range of environments and vegetation from moderate climate supporting regional forests to relatively cold, dry parkland. New Uranium-Thorium data (99 ± 20 ka and 101 ± 13 ka), along with environmental reconstructions, indicate that the lower unit was probably formed during one of the cold sub-stages towards the end the last inter-glaciation (MIS5).

scholarly journals Excursions to C<sub>4</sub> vegetation recorded in the Upper Pleistocene loess of Surduk (Northern Serbia): an organic isotope geochemistry study

2013 ◽  
Vol 9 (3) ◽  
pp. 1001-1014 ◽  
Author(s):  
C. Hatté ◽  
C. Gauthier ◽  
D.-D. Rousseau ◽  
P. Antoine ◽  
M. Fuchs ◽  
...  
Keyword(s):  
General Pattern ◽  
Free Water ◽  
Circulation Pattern ◽  
Water Evaporation ◽  
C3 Plants ◽  
Mean Annual Precipitation ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
The Balkans ◽  
The Mediterranean

Abstract. Loess sequences have been intensively studied to characterize past glacial climates of the 40–50° north and south latitude zones. Combining different approaches of sedimentology, magnetism, geochemistry, geochronology and malacology allows the general pattern of the climate and environment of the last interglacial–glacial cycle in Eurasia and America to be characterized. Previous studies performed in Europe have highlighted the predominance (if not the sole occurrence) of C3 vegetation. The presence of C3 plants suggests a regular distribution of precipitation along the year. Therefore, even if the mean annual precipitation remained very low during the most extensive glacial times, free water was available for more than 2 months per year. Contrarily, the δ13C record of Surduk (Serbia) clearly shows the occurrence and dominance of C4 plants during at least 4 episodes of the last glacial times at 28.0–26.0 kyr cal BP, 31.4–30.0 kyr cal BP, 53.4–44.5 kyr cal BP and 86.8–66.1 kyr. The C4 plant development is interpreted as a specific atmospheric circulation pattern that induces short and dry summer conditions. As possible explanation, we propose that during "C4 episodes", the Mediterranean Sea would have been under the combined influence of the following: (i) a strong meridional circulation unfavorable to water evaporation that reduced the Mediterranean precipitation on the Balkans; and (ii) a high positive North Atlantic Western Russian (NA/WR)-like atmospheric pattern that favored northerlies over westerlies and reduced Atlantic precipitation over the Balkans. This configuration would imply very dry summers that did not allow C3 plants to grow, thus supporting C4 development. The intra-"C4 episode" periods would have occurred under less drastic oceanic and atmospheric patterns that made the influence of westerlies on the Balkans possible.

scholarly journals Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial

2011 ◽  
Vol 7 (2) ◽  
pp. 1195-1233 ◽  
Author(s):  
G. Trommer ◽  
M. Siccha ◽  
E. J. Rohling ◽  
K. Grant ◽  
M. T. J. van der Meer ◽  
...  
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Planktonic Foraminifera ◽  
Gulf Of Aden ◽  
Last Interglacial ◽  
The Holocene ◽  
Circulation Mode ◽  
Monsoon Strength ◽  
Mis 5E ◽  
Mis 5

Abstract. This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktonic foraminiferal fauna following high salinities during MIS 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktonic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea SST increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktonic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktonic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.

Correlation and interpretation of paleosols and loess across European Russia and Asia over the last interglacial–glacial cycle

2003 ◽  
Vol 60 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Nathaniel W. Rutter ◽  
Dean Rokosh ◽  
Michael E. Evans ◽  
Edward C. Little ◽  
Jiri Chlachula ◽  
...  
Keyword(s):  
Loess Plateau ◽  
European Russia ◽  
Chinese Loess Plateau ◽  
Russian Plain ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Central Siberia ◽  
Chinese Loess ◽  
Loess Deposition ◽  
The Chinese Loess Plateau

AbstractLoess-paleosol sequences of the last interglacial-glacial cycle are correlated from European Russia to central Siberia and the Chinese Loess Plateau. During cold periods represented by marine oxygen isotope stages (OIS) 2 and 4, loess deposition dominated in the Russian Plain and the Loess Plateau. In central Siberia, loess deposition took place also, but five to seven thin, weakly developed paleosols are identified in both stages. OIS 3, in the Chinese Loess Plateau near Yangchang, consists of a loess bed that is flanked by two weakly developed paleosols. At Kurtak, Siberia, OIS 3 is represented by two distinct, stacked paleosols with no loess bed separating the paleosols. In the Russian Plain, OIS 3 consists of a single, possibly welded paleosol, representing upper and lower stage-3 climates. Brunisols and Chernozems dominate the profiles in China and Siberia, whereas Regosols, Luvisols, and Chernozems are evident in the northern and southern Russian Plain, respectively. OIS 5 is represented in China and the Russian Plain by pedo complexes in a series of welded soils, whereas in contrast, the Kurtak site consists of six paleosols with interbedded loess. The paleosols consist largely of Brunisols and Chernozems. Although the three areas examined have different climates, geographical settings, and loess source areas, they all had similar climate changes during the last interglacial-glacial cycle.

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