Orbital and millennium scale environmental changes in the southern Bering Sea during the last glacial-Holocene: Geochemical and paleontological evidence

The high-resolution Monticchio (MON) sediment record has been demonstrated to be a key archive for reconstructing climate and environmental changes in the central Mediterranean for the last glacial-interglacial cycle. New sediment cores have been retrieved in April 2016 to investigate particularly the transition from the Last Glacial Maximum into the Holocene with a new high-resolution methodological approach. A floating varve chronology spanning ca. 8,000 years has been established by varve counting on thin sections using a petrographic microscope and layer thickness based sedimentation rate estimates for non- or poorly varved intervals. Varve counting is based on detailed seasonal deposition models of five different varve types. The resulting floating chronology consist of 66.6% individually counted varves and 33.4% interpolated years. The uncertainty estimate of the floating chronology has been determined by double counting and amounts to &#177;5.8%.The floating chronology is anchored to an absolute chronology using the Agnano Pomici Principali tephra, dated at 11,999&#177;52 cal yrs BP from paleosols overlying proximal tephra (Bronk Ramsey et al. 2015), is a suitable anchoring point to cross correlation. The resulting varve-based chronology has been compared with several other marker tephras dated elsewhere including the Soccavo 4 tephra (11,700&#177;150 cal yrs BP), the Neapolitan Yellow Tuff (NYT; 14,194&#177;172 cal yrs BP) and the Greenish tephra (19226&#177;104 cal yrs BP). Further comparison with published (Hajdas et al. 1997) and new radiocarbon dates from different terrestrial macro remains are discussed in this paper. This study presents an independent chronology for the last glacial/interglacial transition for a comparison of MON data with high-resolution lake records western and central Europe.ReferencesBronk Ramsey, C., P. G. Albert, S. P. E. Blockley, M. Hardiman, R. A. Housley, C. S. Lane, S. Lee, I. P. Matthews, V. C. Smith & J. J. Lowe (2015) Improved age estimates for key Late Quaternary European tephra horizons in the RESET lattice. Quaternary Science Reviews, 118, 18-32.Hajdas, I., G. Bonani, B. Zolitschka, A. Brauer & J. Negendank (1997) 14C Ages of Terrestrial Macrofossils from Lago Grande Di Monticchio (Italy). Radiocarbon, 40, 803-807.

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Human Evolution and Environmental Changes in the Late Cenozoic. Hominid Adaptations in the Last Glacial of Central Europe.

Journal of Geography (Chigaku Zasshi) ◽

10.5026/jgeography.111.6_840 ◽

2002 ◽

Vol 111 (6) ◽

pp. 840-848 ◽

Cited By ~ 1

Author(s):

Akira ONO

Keyword(s):

Central Europe ◽

Human Evolution ◽

Environmental Changes ◽

Late Cenozoic ◽

Last Glacial ◽

The Last Glacial

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Cliff-front aeolian and colluvial deposits, Mallorca, Western Mediterranean: a record of climatic and environmental change during the last glacial period

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-2001-48-13 ◽

2001 ◽

Vol 48 ◽

pp. 217-232

Author(s):

Lars B. Clemmensen ◽

Thomas Lisborg ◽

Richard G. Bromley ◽

Joan J. Fornós

Keyword(s):

Environmental Change ◽

Environmental Changes ◽

Western Mediterranean ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

Aeolian Deposits ◽

Climatic And Environmental Change ◽

Sea Cliff ◽

The Last Glacial

Large, cliff-front accumulations of Late Pleistocene aeolian and colluvial deposits on southeast Mallorca provide a terrestrial record of climatic and environmental change in the Western Mediterranean during the last glacial period. The cliff-front deposits are lithified and form ramps sloping toward the southeast (i.e. seaward). Radiocarbon dating suggests that the deposits formed in Oxygen Isope Stage 3, when sea level was about 50 m lower than today, and the fossil sea-cliff situated 1.5 to 2 km from the palaeo-shore. The aeolian deposits are composed of marine carbonate sand that was transported inland episodically and accumulated in embayments along the fossil sea-cliff. The sand initially formed steadily growing and forward-moving dunes, then sloping sand ramps and finally relatively small ascending dunes. Aeolian accumulation was interrupted by erosion and colluvial ramp formation, and the cliff-front sediments can be divided into two sedimentary cycles each composed of basal colluvial deposits overlain by aeolian deposits. Colluvial deposition probably records relatively humid climatic intervals, whereas aeolian accumulation probably reflects relatively arid climatic intervals. It appears that climatic and environmental changes were rapid, and it is speculated that the dynamics of the cliff-front system on Mallorca were tied to North Atlantic millennial-scale climate oscillations.

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Were the Larsemann Hills ice-free through the Last Glacial Maximum?

Antarctic Science ◽

10.1017/s0954102001000608 ◽

2001 ◽

Vol 13 (4) ◽

pp. 440-454 ◽

Cited By ~ 107

Author(s):

D.A. Hodgson ◽

P.E. Noon ◽

W. Vyverman ◽

C.L. Bryant ◽

D.B. Gore ◽

...

Keyword(s):

Last Glacial Maximum ◽

Climate Changes ◽

Environmental Changes ◽

Glacial Maximum ◽

Radiometric Dating ◽

Supporting Evidence ◽

Last Glacial ◽

Larsemann Hills ◽

The Last Glacial Maximum ◽

The Last Glacial

Lake sediments in the Larsemann Hills contain a great diversity of biological and physical markers from which past environments can be inferred. In order to determine the timing of environmental changes it is essential to have accurate dating of sediments. We used radiometric (210Pb and 137Cs), radiocarbon (AMS 14C) and uranium series (238U) methods to date cores from eleven lakes. These were sampled on coastal to inland transects across the two main peninsulas, Broknes and Stornes, together with a single sample from the Bolingen Islands. Radiometric dating of recent sediments yielded 210Pb levels below acceptable detection limits. However, a relatively well-defined peak in 137Cs gave a date marker which corresponds to the fallout maximum from the atmospheric testing of atomic weapons in 1964/65. Radiocarbon (AMS 14C) measurements showed stratigraphical consistency in the age-depth sequences and undisturbed laminae in some cores provides evidence that the sediments have remained undisturbed by glacial action. In addition, freshwater surface sediments were found to be in near-equilibrium with modern 14CO2 and not influenced by radiocarbon contamination processes. This dating program, together with geomorphological records of ice flow directions and glacial sediments, indicates that parts of Broknes were ice-free throughout the Last Glacial Maximum and that some lakes have existed continuously since at least 44 ka bp. Attempts to date sediments older than 44 ka bp using 128U dating were inconclusive. However, supporting evidence for Broknes being ice-free is provided by an Optically Stimulated Luminescence date from a glaciofluvial deposit. In contrast, Stornes only became ice-free in the mid to late Holocene. This contrasting glacial history results from the Dålk Glacier which diverts ice around Broknes. Lakes on Broknes and some offshore islands therefore contain the oldest known lacustrine sediment records from eastern Antarctica, with the area providing an ice-free oasis and refuge for plants and animals throughout the Last Glacial Maximum. These sediments are therefore well placed to unravel a unique limnological sequence of environmental and climate changes in East Antarctica from the late Pleistocene to the present. This information may help better constrain models of current climate changes and ensure the adequate protection of these lakes and their catchments from the impacts of recent human occupation.

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