Stable isotope and 14C study of biogenic calcrete in a termite mound, Western Cape, South Africa, and its palaeoenvironmental significance

2009 ◽  
Vol 72 (2) ◽  
pp. 258-264 ◽  
Author(s):  
Alastair J. Potts ◽  
Jeremy J. Midgley ◽  
Chris Harris
Keyword(s):  
South Africa ◽  
Arid Zone ◽  
Late Quaternary ◽  
Western Cape ◽  
Cam Plants ◽  
Termite Mounds ◽  
Last Glacial Period ◽  
Radiocarbon Dates ◽  
Progressive Decline ◽  
The Last Glacial

AbstractLate Quaternary terrestrial climate records from the semi-arid zone of the Western Cape of South Africa are rare. However, palaeoenvironmental information may be inferred from ancient termite mounds of the region. Calcrete lenses in these mounds have δ13C and δ18O values that show systematic changes with radiocarbon dates, which range from 33,629–36,709 to 21,676–23,256 cal yr BP. These dates confirm that these heuweltjies had been present in the landscape since the last glacial period. The decrease in δ13C and δ18O from 33,629–36,709 to 21,676–23,256 cal yr BP indicates that climate information is recorded by the calcretes. It is suggested that a progressive decline in air temperature and an increase in moisture availability, and a decline in abundance of C4 or CAM plants, occurred in the region during the time heuweltjie calcite precipitated.

Late Quaternary Paleotemperatures Derived from a Speleothem from Cango Caves, Cape Province, South Africa

1992 ◽  
Vol 37 (2) ◽  
pp. 203-213 ◽  
Author(s):  
A.S. Talma ◽  
John C. Vogel
Keyword(s):  
South Africa ◽  
Isotopic Composition ◽  
Late Quaternary ◽  
Carbon Isotopic Composition ◽  
Temperature Record ◽  
The Past ◽  
Carbon Isotopic ◽  
Groundwater Aquifer ◽  
Combining Data ◽  
The Last Glacial

AbstractAn oxygen isotope temperature record over a large part of the past 30,000 yr has been obtained for the southern Cape Province of South Africa by combining data on the isotopic composition of a stalagmite from a deep cave with that of a confined groundwater aquifer in the same region. Results show that temperatures during the last glacial maximum were on average about 6°C lower than those today, with peaks up to 7°C lower. A detailed analysis of the past 5000 yr suggests multiple fluctuations, with generally lower temperatures (1–2°C) around 4500 and 3000 yr B.P. The carbon isotopic composition of the stalagmite indicates significant vegetation changes between the late Pleistocene and today, and also during the second half of the Holocene.

Late Quaternary micromammals and the precipitation history of the southern Cape, South Africa

2018 ◽  
Vol 91 (2) ◽  
pp. 848-860 ◽  
Author(s):  
J. Tyler Faith ◽  
Brian M. Chase ◽  
D. Margaret Avery
Keyword(s):  
South Africa ◽  
Late Quaternary ◽  
Regional Climate ◽  
Summer Rainfall ◽  
Tyto Alba ◽  
Winter Rainfall ◽  
Rainfall Seasonality ◽  
Barn Owls ◽  
History Of ◽  
The Last Glacial

AbstractThe southern Cape of South Africa is important to understanding regional climate because it straddles the transition between the winter and summer rainfall zones. We examine late Quaternary changes in rainfall seasonality and aridity through analysis of micromammal assemblages from three sites: Boomplaas Cave and Nelson Bay Cave in the aseasonal rainfall zone and Byneskranskop 1 in the winter rainfall zone. Our interpretation is based on analysis of 123 modern micromammal assemblages accumulated by barn owls (Tyto alba), which empirically links species composition to climate. The Pleistocene record (∼65 to 12 ka) from Boomplaas Cave, together with the last glacial maximum (LGM) samples from Nelson Bay Cave, indicates enhanced winter rainfall, especially during the LGM. Boomplaas Cave documents progressive aridification from the LGM to the earliest Holocene, followed by a return to moderately humid conditions through the Holocene. Byneskranskop 1 indicates a dominance of winter rains over the last 17 ka and a shift from an arid middle Holocene to a humid later Holocene. Agreement between the micromammal record and other local and regional proxies reinforces the potential of southern African micromammal assemblages as paleoclimate indicators.

scholarly journals Approaches to Estimating Marine Protein in Human Collagen for Radiocarbon Date Calibration

Radiocarbon ◽  
2010 ◽  
Vol 52 (4) ◽  
pp. 1611-1625 ◽  
Author(s):  
Genevieve Dewar ◽  
Susan Pfeiffer
Keyword(s):  
South Africa ◽  
Case Studies ◽  
Carbon Isotope ◽  
Nitrogen Isotope ◽  
Western Cape ◽  
Radiocarbon Dates ◽  
Mean Values ◽  
Marine Systems ◽  
Human Collagen ◽  
Marine Protein

Determining the appropriate approach to calibrating radiocarbon dates is challenging when unknown and variable fractions of the carbon sample are derived from terrestrial and marine systems. Uncalibrated dates from a large number of human skeletons from Western Cape and Southern Cape locales, South Africa (n = 187), can be used to explore alternate approaches to the marine carbon correction. The approach that estimates theoretically expected minimum and maximum values for marine carbon (“expected”) is compared to the approach that estimates observed minimum and maximum values (“observed”). Two case studies are explored, wherein skeletons interred together have non-overlapping conventional 14C ages. The case from the Western Cape is explored through carbon isotope values; the case from the Southern Cape uses nitrogen isotope values. In both cases, the approach using observed endpoints yields better date calibration results. Analysis of the large sample shows that mean values for estimated dietary % Marine, as calculated using expected and observed protocols, are significantly different. We conclude that the observed protocol is preferred, and that improved measures of the local marine reservoir (ΔR) are needed for this region.

Pollen Diagram from the Nebraska Sandhills and the Age of the Dunes

1985 ◽  
Vol 24 (1) ◽  
pp. 115-120 ◽  
Author(s):  
H. E. Wright ◽  
J. C. Almendinger ◽  
J. Grüger
Keyword(s):  
Sand Dunes ◽  
Dune Sand ◽  
Last Glacial Period ◽  
Pollen Diagram ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Swan Lake ◽  
Nebraska Sandhills ◽  
Prairie Vegetation ◽  
The Last Glacial

Radiocarbon dates of organic alluvium beneath as much as 40 m of dune sand along the Dismal River have led to the suggestion that the Nebraska Sandhills date from the Holocene rather than the last glacial period. On the other hand, the basal layers of lake and marsh deposits in interdune depressions at three localities date in the range of 9000 to 12,000 yr B.P., implying a pre-Holocene age for the sand dunes. A pollen diagram for one of these sites, Swan Lake, indicates prairie vegetation throughout the last 9000 yr, with no suggestion that the landscape was barren enough to permit the shaping of the massive dunes characterizing the area. Sand was not transported across the site during the Holocene, either during the marsh phase, which lasted until 3700 yr B.P., or during the subsequent lake phase. The sand that buries the alluvium along the Dismal River may represent only local eolian activity, or it may indicate that the younger of the two main dune series identified by H. T. U. Smith (1965, Journal of Geology 73, 557–578) is Holocene in age, and the older one Late Wisconsin in age.

Tephra anchored floating varve chronology covering ca. 19.0-11.0 ka BP in new core from Lake Lago Grande di Monticchio: preliminary results

2020 ◽  
Author(s):  
Xueru Zhao ◽  
Sabine Wulf ◽  
Markus J. Schwab ◽  
Rik Tjallingii ◽  
Achim Brauer
Keyword(s):  
High Resolution ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Methodological Approach ◽  
Radiocarbon Dates ◽  
Thin Sections ◽  
Last Glacial ◽  
Varve Chronology ◽  
Varve Counting ◽  
The Last Glacial

<p>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 ±5.8%.</p><p>The floating chronology is anchored to an absolute chronology using the Agnano Pomici Principali tephra, dated at 11,999±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±150 cal yrs BP), the Neapolitan Yellow Tuff (NYT; 14,194±172 cal yrs BP) and the Greenish tephra (19226±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.</p><p>References</p><p>Bronk 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<strong>,</strong> 18-32.</p><p>Hajdas, I., G. Bonani, B. Zolitschka, A. Brauer & J. Negendank (1997) 14C Ages of Terrestrial Macrofossils from Lago Grande Di Monticchio (Italy). Radiocarbon, 40<strong>,</strong> 803-807.</p>

Late Quaternary Arthropod Remains from Sonoran Desert Packrat Middens, Southwestern Arizona and Northwestern Sonora

1988 ◽  
Vol 29 (3) ◽  
pp. 277-293 ◽  
Author(s):  
W. Eugene Hall ◽  
Thomas R. Van Devender ◽  
Carl A. Olson
Keyword(s):  
Sonoran Desert ◽  
Colorado River ◽  
Late Quaternary ◽  
Taxonomic Resolution ◽  
Radiocarbon Dates ◽  
Temperature And Precipitation ◽  
Arthropod Fauna ◽  
Juniper Woodland ◽  
Insufficient Knowledge ◽  
The Last Glacial

A total of 50 arthropod taxa were identified from 41 fossil packrat (Neotoma sp.) middens from 160 to 625 m elevation in three study areas in the Lower Colorado River Valley subdivision of the Sonoran Desert. Radiocarbon dates associated with the middens range from >43,200 to 610 yr B.P. The fauna in the Tinajas Altas Mountains, southwestern Arizona, was relatively modern by ca. 10,000 yr B.P. in the early Holocene although a California juniper woodland persisted in the area until 8970 yr B.P. In contrast the fauna of the Hornaday Mountains, northwestern Sonora, increased dramatically in species richness after 4000 yr B.P. Although we are limited by poor taxonomic resolution and by insufficient knowledge of current distributions, the arthropod fauna may have been much more conservative than the regional flora during the last glacial/interglacial climatic cycle. Decreasing differences between modern and glacial climates (both temperature and precipitation) at lower latitudes and elevations may have resulted in minimal changes in the arthropod fauna of the Sonoran Desert lowlands.

scholarly journals Underwater faunal assemblages: radiocarbon dates and late Quaternary vertebrates from Cold Lake, Alberta and Saskatchewan, Canada

2018 ◽  
Vol 55 (3) ◽  
pp. 283-294
Author(s):  
Christopher N. Jass ◽  
Devyn Caldwell ◽  
Christina I. Barrón-Ortiz ◽  
Alwynne B. Beaudoin ◽  
Jack Brink ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Faunal Remains ◽  
Radiocarbon Dates ◽  
East Central ◽  
Faunal Assemblages ◽  
History Of ◽  
Cold Lake ◽  
The Last Glacial Maximum ◽  
Insight Into ◽  
The Last Glacial

Late Quaternary faunal remains from three underwater settings in Cold Lake, Alberta and Saskatchewan, Canada, include at least 13 vertebrate taxa consistent with assemblages that postdate the Last Glacial Maximum (LGM). Seven new radiocarbon dates range from 10 350 ± 40 to 161 ± 23 years BP and provide insight into the post-LGM biotic history of east-central Alberta and west-central Saskatchewan. The presence of an essentially modern large mammal biota is suggested for the mid-Holocene, and possibly earlier, if the absence of extinct or extirpated taxa in association with Late Pleistocene Bison at the Alberta–Saskatchewan site is meaningful. Taphonomically, some of the remains suggest deposition in open environments during the Holocene, possibly when lake levels were lower. The recovery of late Quaternary faunal remains from a present-day lacustrine setting is novel, and suggests that similar records may occur in other lakes in western Canada, including those in areas with scarce Quaternary vertebrate records.

Controls on stratigraphic variability in a semi-closed rift basin over the Late Quaternary, Gulf of Corinth, Greece

2020 ◽  
Author(s):  
Sofia Pechlivanidou ◽  
Spyros Sergiou ◽  
Maria Geraga ◽  
Robert Gawthorpe ◽  
Dimitra Antoniou ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Ct Scanning ◽  
Rift Basin ◽  
Last Glacial Period ◽  
Corinth Gulf ◽  
Fine Grained ◽  
Gulf Of Corinth ◽  
Cyclic Variations ◽  
The Last Glacial

<p>The Corinth Gulf is a semi-closed active rift basin, which alternated between marine and isolated/semi-isolated conditions as sea level fluctuated with respect to basin sills during Quaternary glacial/interglacial cycles. Results from the recent IODP Expedition 381 reveal cyclic variations of 10s-100s of kyr in sedimentation rates and basin paleoenvironment. In this study we investigate the controls on stratigraphic development of the Corinth basin during the last eustatic cycle and the Holocene based on core data from the IODP Expedition 381 Site M0079. We perform a multi-proxy analysis of the upper ~200 mbsf of core covering Marine Isotope Stages (MIS) 1-5 (i.e. last 130 kyr). Our analyses include grain size and micropaleontological (foraminifera) analyses at regular intervals (~0.5 m), Computed Tomography (CT-scanning) of selected u-channels and specific microscopic work (smear slides, SEM) on targeted samples. Our results show pronounced variability in sedimentation patterns during the isolated/semi-isolated phases compared to the marine intervals. Low density, thinly bedded and laminated muds alternating with high density homogenous mud beds and occasionally sandy, organic rich beds prevail during isolated/semi-isolated conditions. In contrast, homogenous and/or highly bioturbated successions characterize the marine sequences. The transitions from marine to isolated/semi-isolated conditions and vise-versa are often associated with authigenic carbonate deposition. Fine grained sediments (sand < 10%) dominate both the marine and the isolated sequences. Nevertheless, sandy turbidites (sand > 10%) are also present and are more often observed in the isolated phases, likely associated with climatic-driven changes in erosional processes onshore. Our analysis reveals short-lived isolated/semi-isolated sub-phases within the lower marine interval corresponding to the MIS5b and MIS5d lowstands. Short marine spikes also interrupt the isolated/semi-isolated conditions of the last glacial period indicating temporary sea level rises within MIS3. Overall, the marine intervals display significant paleoenvironmental differences although they share similar sedimentary patters. In particular, we observe more diverse palaeoceanographic conditions in the MIS5 marine sub-phases compared to the MIS1, especially regarding temperature and eutrophication levels of the water column.  </p>

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