scholarly journals Detailed palaeomagnetic record at Rose Cottage Cave, South Africa: Implications for the Holocene geomagnetic field behaviour and chronostratigraphy

2020 ◽  
Vol 116 (1/2) ◽  
Author(s):  
Hugo G. Nami ◽  
Carlos A. Vasquez ◽  
Lyn Wadley ◽  
Paloma de la Peña
Keyword(s):  
South Africa ◽  
Rock Magnetism ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Sedimentary Deposits ◽  
Directional Analysis ◽  
Palaeomagnetic Data ◽  
Natural Remanent Magnetisation ◽  
Terminal Pleistocene ◽  
Field Behaviour

Palaeomagnetic data from a sedimentary section spanning the Holocene and terminal Pleistocene (~13 kya) from Rose Cottage Cave, eastern Free State (South Africa), are reported. The palaeomagnetic analysis took into account rock magnetism and directional analysis. The former reveals that most samples show stable single domain and superparamagnetic particles of Ti-poor magnetite and haematite. Natural remanent magnetisation directions were determined by progressive alternating field demagnetisation methodology. Directional analysis shows normal directions between samples 18 to 39 and 85 to 92; however, during the Early and Late Holocene in samples principally from RC40 to 84 ‘anomalous’ directions occurred. There is a significant westward shift in declination of ~80°, and a conspicuous fluctuating inclination in the lower part of the section during the Early Holocene at ≥9.5 kya and before ~12.0/13.0 kya. This palaeomagnetic record might become a chronostratigraphical marker for latest Pleistocene/Holocene sedimentary deposits in South Africa. Our two new accelerator mass spectrometry radiocarbon dates for the sampled deposit are 9500±50 BP and 1115±30 BP.

scholarly journals Radiocarbon Dates Constrain the Timing of Environmental and Cultural Shifts in the Holocene Strata of Wonderwerk Cave, South Africa

Radiocarbon ◽  
2017 ◽  
Vol 59 (4) ◽  
pp. 1067-1086 ◽  
Author(s):  
Michaela Ecker ◽  
James Brink ◽  
Michael Chazan ◽  
Liora Kolska Horwitz ◽  
Julia A Lee-Thorp
Keyword(s):  
South Africa ◽  
Bayesian Model ◽  
Later Stone Age ◽  
Human Occupation ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Proposed Model ◽  
Climate Shifts ◽  
Cultural Shifts ◽  
Age Estimates

AbstractWonderwerk Cave has yielded one of the longest and most complete Holocene Later Stone Age (LSA) records for the arid interior of South Africa. This paper presents the results of a new radiocarbon dating program for Excavation 1 that is explored within a Bayesian model of all existing Wonderwerk Cave radiocarbon (14C) dates for the Holocene. The proposed model, usingPhaseswithin an OxCalSequencemodel, provides robust age estimates for changes in the technological and paleoenvironmental record at the site. The more precise dates allow a comparison of the timing of climate shifts across the interior of southern Africa and begin to allow us to identify whether hiatuses in human occupation, or cultural shifts, are synchronous across broader areas of the subcontinent, or not.

scholarly journals First radiocarbon dated paleoecological data from the freshwater carbonates of the Danube-Tisza Interfluve

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Pál Sümegi ◽  
Dávid Molnár ◽  
Szilvia Sávai ◽  
Katalin Náfrádi ◽  
Zsolt Novák ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Chronological Order ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Regional Comparison ◽  
Paleoenvironmental Changes ◽  
Sedimentary Sequences ◽  
Terminal Pleistocene ◽  
Freshwater Carbonates

AbstractThe first radiocarbon dates available on the evolution of the freshwater carbonates of the Danube-Tisza Interfluve are presented in this work along with their possible uses to precisely date paleoecological and paleoenvironmental changes. This work also gives the basis of a comparative analysis of the Holocene radiocarbon-dated profile of Csólyospálos with other Hungarian radiocarbondated profiles of the same age (Bátorliget, the Sárrét, etc.) and the implementation of a detailed chronological and regional paleoenvironmental study. Furthermore, our findings clearly demonstrate the importance of radiocarbon analysis in the study of terminal Pleistocene and Holocene Hungarian sedimentary sequences for accurately dating and reconstructing the chronological order of paleoenvironmental changes as well as the evolution of the natural endowments plus the regional comparison of the various profiles.

scholarly journals Palaeomagnetic results and new dates of sedimentary deposits from Klasies River Cave 1, South Africa

2016 ◽  
Vol Volume 112 (Number 11/12) ◽  
Author(s):  
Hugo G. Nami ◽  
Paloma de la Peña ◽  
Carlos A. Vásquez ◽  
James Feathers ◽  
Paloma de la Peña ◽  
...  
Keyword(s):  
South Africa ◽  
Late Pleistocene ◽  
Rock Magnetism ◽  
Middle Stone Age ◽  
Stone Age ◽  
Radiocarbon Dates ◽  
Main Site ◽  
White Sand ◽  
Remanent Magnetisation ◽  
Field Excursion

Abstract Palaeomagnetic data from Klasies River main site Cave 1 (Eastern Cape Province, South Africa) are reported. Natural remanent magnetisation directions obtained from 77 oriented samples were determined by progressive alternating field demagnetisation methodology. Three palaeomagnetic samplings from the Witness Baulk from the Middle Stone Age (MSA) Late Pleistocene White Sand member and the Holocene Later Stone Age (LSA) middens in Cave 1 were dated and analysed to obtain the palaeomagnetic directions recorded in the sediments. Here we provide new optically stimulated luminescence (OSL) dates for the White Sand Member, and new accelerator mass spectrometry (AMS) radiocarbon dates for the LSA midden of areas not previously dated. The palaeomagnetic analysis took into account rock magnetism and directional analysis. The former reveals that the main magnetic carrier was magnetite; the latter shows that characteristic remanent magnetisation of normal and anomalous directions was observed in the lower portion of the White Sand Member and LSA midden. Normal directions correspond to the palaeosecular variation record for South Africa during the Late Pleistocene. On the other hand, the anomalous directions recorded in the LSA midden might represent the likely Sterno-Etrussia geomagnetic field excursion which occurred during the Late Holocene and is observed in other places on the planet. Finally, the directional data obtained are a potential tool for discussing the age of deposits corresponding to those periods.

scholarly journals Calibration of Radiocarbon Dates for the Late Pleistocene Using U/Th Dates on Stalagmites

Radiocarbon ◽  
1997 ◽  
Vol 39 (1) ◽  
pp. 27-32 ◽  
Author(s):  
John C. Vogel ◽  
Joel Kronfeld
Keyword(s):  
South Africa ◽  
Magnetic Dipole ◽  
Satisfactory Agreement ◽  
Late Pleistocene ◽  
Calibration Curve ◽  
Dipole Field ◽  
Radiocarbon Dates ◽  
The Past ◽  
The Earth ◽  
Magnetic Dipole Field

Twenty paired 14C and U/Th dates covering most of the past 50,000 yr have been obtained on a stalagmite from the Cango Caves in South Africa as well as some additional age-pairs on two stalagmites from Tasmania that partially fill a gap between 7 ka and 17 ka ago. After allowance is made for the initial apparent 14C ages, the age-pairs between 7 ka and 20 ka show satisfactory agreement with the coral data of Bard et al. (1990, 1993). The results for the Cango stalagmite between 25 ka and 50 ka show the 14C dates to be substantially younger than the U/Th dates except at 49 ka and 29 ka, where near correspondence occurs. The discrepancies may be explained by variations in 14C production caused by changes in the magnetic dipole field of the Earth. A tentative calibration curve for this period is offered.

The sensitivity of Neotoma to climate change and biodiversity loss over the late Quaternary

2021 ◽  
pp. 1-15
Author(s):  
Catalina P. Tomé ◽  
S. Kathleen Lyons ◽  
Seth D. Newsome ◽  
Felisa A. Smith
Keyword(s):  
Body Size ◽  
Late Quaternary ◽  
Climatic Variability ◽  
Isotope Analysis ◽  
Biodiversity Loss ◽  
Bone Collagen ◽  
Cam Plants ◽  
The Holocene ◽  
Carbon And Nitrogen ◽  
Terminal Pleistocene

Abstract The late Quaternary in North America was marked by highly variable climate and considerable biodiversity loss including a megafaunal extinction event at the terminal Pleistocene. Here, we focus on changes in body size and diet in Neotoma (woodrats) in response to these ecological perturbations using the fossil record from the Edwards Plateau (Texas) across the past 20,000 years. Body mass was estimated using measurements of fossil teeth and diet was quantified using stable isotope analysis of carbon and nitrogen from fossil bone collagen. Prior to ca. 7000 cal yr BP, maximum mass was positively correlated to precipitation and negatively correlated to temperature. Independently, mass was negatively correlated to community composition, becoming more similar to modern over time. Neotoma diet in the Pleistocene was primarily sourced from C3 plants, but became progressively more reliant on C4 (and potentially CAM) plants through the Holocene. Decreasing population mass and higher C4/CAM consumption was associated with a transition from a mesic to xeric landscape. Our results suggest that Neotoma responded to climatic variability during the terminal Pleistocene through changes in body size, while changes in resource availability during the Holocene likely led to shifts in the relative abundance of different Neotoma species in the community.

The last glaciation and sea level history of Fosheim Peninsula, Ellesmere Island, Canadian High Arctic

1996 ◽  
Vol 33 (7) ◽  
pp. 1075-1086 ◽  
Author(s):  
Trevor Bell
Keyword(s):  
High Arctic ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Ice Caps ◽  
Marine Deposits ◽  
Last Glaciation ◽  
Maximum Elevation ◽  
Glacier Runoff ◽  
History Of ◽  
Ice Conditions

The last glaciation of Fosheim Peninsula is reconstructed on the basis of landform and sediment mapping and associated radiocarbon dates. Ice growth involved the expansion of cirque glaciers and accumulation on upland surfaces that are now ice free. Limited ice buildup, despite lowering of the paleoglaciation level by 700–800 m, is attributed to the hyperaridity of the region during glacial conditions. Marine deposits in formerly submerged basins beyond the ice margins are interpreted to represent (i) sedimentation caused by local ice buildup and marine transgression by 10.6 ka BP, (ii) increased ablation and glacier runoff [Formula: see text]9.5 ka BP, and (iii) marine regression during the Holocene. Holocene marine limit reaches a maximum elevation of approximately 150 m asl along northern Eureka Sound and Greely Fiord and descends southeastwards to 139–142 m asl near the Sawtooth Mountains. A synchronous marine limit is implied where the last ice limit was inland of the sea. The magnitude and pattern of Holocene emergence cannot be fully explained by the glacioisostatic effects of the small ice load during the last glaciation of the region. Deglaciation of the peninsula was underway by 9.5 ka BP; however, local ice caps may have persisted through the wannest period of the Holocene until 6–5 ka BP. This was likely a function of reduced sea ice conditions and increased moisture availability which benefited low-lying coastal icefields, but had negligible effect on interior highland ice caps.

Holocene evolution of the Assiniboine River paleochannels and Portage la Prairie alluvial fan

1989 ◽  
Vol 26 (9) ◽  
pp. 1834-1841 ◽  
Author(s):  
W. F. Rannie ◽  
L. H. Thorleifson ◽  
J. T. Teller
Keyword(s):  
Alluvial Fan ◽  
Red River ◽  
Lake Agassiz ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Sediment Loads ◽  
History Of ◽  
Western Side

The Portage la Prairie alluvial fan was constructed by numerous successive paleochannels of the Assiniboine River along the western side of the Lake Agassiz basin as the level of the lake rapidly declined beginning 9500 years ago. The history of the paleochannels during the first several thousand years is not known. Paleochannel morphologies and cross-cutting relations, soil maturity, and radiocarbon dates, however, indicate that by 6000–7000 years ago flow was northward into Lake Manitoba. This direction was maintained until about 3000 years ago, when avulsion redirected the Assiniboine eastward to the Red River near Winnipeg. The morphologies of the paleochannels suggest that channel-forming discharges and sediment loads of the ancestral rivers have not differed significantly from the modern values despite palynological evidence that the climate was warmer and drier during much of the Holocene.

Quaternary North American Vegetational History: 1.6 Ma to the Present

1999 ◽  
Author(s):  
Alan Graham
Keyword(s):  
United States ◽  
Mississippi River ◽  
Ice Age ◽  
Quaternary Period ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Oxygen Isotope Stage ◽  
Continental Scale ◽  
Northern Latitudes ◽  
The University

The Quaternary Period encompasses the Pleistocene and the Holocene or Recent Epochs. The date used for the beginning of the Pleistocene depends upon which globally recognizable event is selected as representing a significant break with the preceding Pliocene Epoch. Candidates include the Gauss-Matuyama magnetopolarity boundary (~2.8 Ma; see Quaternary International, 1997); the initiation of widespread permafrost, a frigid Arctic Ocean, and rapid glaciation in the high northern latitudes (~2.4 Ma; Shackleton and Opdyke, 1977; Shackleton et al., 1984); or the African Olduvai paleomagnetic event between 1.87 and 1.67 Ma. The transition from hothouse to icehouse conditions was gradual, but the Pleistocene is typified at Vrica, Italy, as beginning at ~1.67 Ma (Aguirre and Pasini, 1985; Richmond and Fullerton, 1986; oxygen isotope stage 62), and that is the date used here. In the conterminous United States the Elk Creek till of Nebraska is 2.14 m.y. in age (Hallberg, 1986), and the onset of the full ice age is represented by the onset of repeated glaciations at ~850 Kya when glaciers extended down the Mississippi River Valley. Subsequently, glacial-interglacial conditions fluctuated until the latest retreat at ~11 Kya that began the Holocene or Recent Epoch. The chronology of ice age events began with the publication of Louis Agassiz’s (1840) Etudes surles Glaciers. In the absence of evidence to the contrary, a single glacial advance was envisioned as blanketing the high latitudes. In the 1940s Willard E Libby at the University of Chicago perfected the technique of radiocarbon dating, and Flint and Rubin (1955) applied this methodology of “isotopic clocks” to establishing the absolute chronology of drift deposits from the eastern and midwestern United States. Their radiocarbon dates showed evidence of two or more times of continental-scale glaciations; older organic material was “radiocarbon inert” and beyond the ~40-Ky range of the technique. A standard chronology eventually became established for North America that included four major glacial stages (Nebraskan, oldest; Kansan; Illinoian; and Wisconsin) separated by four interglacials (Aftonian, oldest; Yarmouth, Sangamon, and the present Holocene).

A comparison of geomagnetic secular variation as recorded by historical, archaeomagnetic and palaeomagnetic measurements

1982 ◽  
Vol 306 (1492) ◽  
pp. 103-112 ◽  
Keyword(s):  
Magnetic Field ◽  
Lake Sediments ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Secular Change ◽  
Mathematical Approach ◽  
Geomagnetic Secular Variation ◽  
The Past ◽  
Palaeomagnetic Data ◽  
Field Behaviour

Palaeomagnetic methods can extend the documentary record of changes in the Earth’s magnetic field far into the past. Tolerable agreement is found between various methods, demonstrating the geophysical value of palaeomagnetic experiments. Combining results from the different approaches of investigating secular change can lead to a better perspective and to superior models of geomagnetic field behaviour. Lake sediments have recently been found to hold remarkably detailed signatures of past field changes. A mathematical approach to formulating an empirical description of global geomagnetic field behaviour is proposed and applied to palaeomagnetic data spanning the last 10 ka.

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