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981.
Domestication is an ongoing co-evolutionary process rather than an event or invention. Recent zooarchaeological and animal
genetics research has prompted a thorough revision of our perspectives on the history of domestic animals in Africa. Genetic
analyses of domestic animal species have revealed that domestic donkeys are descended from African ancestors, opened a debate
over the contribution of indigenous aurochs to African domestic cattle, revealed an earlier and possibly exogenous origin
of the domestic cat, and reframed our vision of African dogs. Genetic diversity studies and mapping of unique traits in African
cattle, sheep, goats, pigs and chickens indicate adaptations to regional environmental challenges and suggest hitherto unknown
and complex patterns of interactions both among Africans and with Southwest Asia and other Asian regions on the Indian Ocean.
This article argues against the static perspective on domestication as invention and for viewing it as a dynamic, locally
based and continuing process. 相似文献
982.
RECORD OF LiU DONG AND HIS ATSATSA COLLECTION 总被引:1,自引:0,他引:1
983.
Khikmatulla Arslanov Olga Druzhinina Larisa Savelieva Dmitry Subetto Ivan Skhodnov Pavel Dolukhanov Gennady Kuzmin Sergey Chernov Fedor Maksimov Segey Kovalenkov 《Geochronometria》2011,38(2):172-181
The raised bog sediments that have been continuously accumulated over time represent the most suitable natural object which
enables us to reconstruct Late Glacial and Holocene vegetation and palaeoclimates. Bog peat consists of organic carbon formed
in situ. It contains moss, plant fragments and microfossils that are necessary for the study of palaeovegetation and palaeoclimate.
However, a successful study of palaeoenvironment can be carried out on the basis of investigation of a great quantity of samples
along the whole peatbog thickness. In the present paper, the authors present the results of palynological, botanical investigations
and radiocarbon dating of 31 peat samples taken from the raised bog Velikoye, located in the eastern part of Kaliningrad Region.
The data obtained have enabled us to reconstruct the palaeovegetation, reveal the evolution of the bog and determine rate
of peat formation at different evolutional stages over the last 7500 cal BP. 相似文献
984.
Estimation of soil erosion on cultivated fields on the hilly Meghalaya Plateau,North-East India 总被引:1,自引:0,他引:1
The estimation of soil erosion rates in complex subtropical agricultural systems of hilly environment is difficult and most
of the traditional methods have serious limitations. The 137Cs technique allows to obtain relatively quickly retrospective medium term soil erosion results. The objective of this study
was using 137Cs approach to quantify soil loss under agricultural system which develops under growing human pressure on the hilly terrain
of the Meghalaya Plateau. The measured values of caesium inventory for all sampling points are between 2% and 63% of the reference
value of caesium inventory. The estimated annual soil loss for sampling points located on the slope are between 29 and 79
Mg·ha−1·yr−1 in the case of an improved mass balance model. It means that soil erosion in this manually tilled agricultural area cannot
be neglected. 相似文献
985.
Bone catapult and hammer-headed pins played one of very specific roles in funerary offerings in the Bronze Age graves uncovered
in the Eurasian Steppes and the North Caucasus. Scholars used different types of pins as key grave offerings for numerous
chronological models. For the first time eight pins have been radiocarbon dated. 14C dating of bone pins identified the catapult type pin as the earliest one. They marked the period of the Yamnaya culture
formation. Then Yamnaya population produced hammer-headed pins which became very popular in other cultural environments and
spread very quickly across the Steppe and the Caucasus during 2900–2650 cal BC. But according to radiocarbon dating bone pins
almost disappeared after 2600 cal BC. 相似文献
986.
Ana-Voica Bojar Stanislaw Halas Hans-Peter Bojar Dan Grigorescu Stefan Vasile 《Geochronometria》2011,38(2):182-188
In order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians,
and correlate it with the other continental unit that occurs in the region, the Sanpetru Formation, we separated and dated
by the K-Ar method biotites and amphiboles from volcanoclastic deposits. The mineral phases analysed are from two tuff layers
and volcanic bombs cropping out near Rachitova village. Two tuff layers from the Densuş-Ciula Formation give early Maastrichtian
ages of 69.8±1.3 and 71.3±1.6 Ma, respectively. The ages determined for the tuff layers constrain the age of deposition for
the Densuş-Ciula Formation and enable further correlations with the available palaeomagnetic data from the deposits occurring
along the Sibişel Valley that belong to the Sanpetru Formation. The volcanic bombs collected near to Răchitova village are
andesites and dacites. The age determined by K-Ar method on hornblende separated from a volcanic bomb is 82.7±1.5 Ma, which
is older than the underlying Campanian marine deposits in turbidite facies. This suggests that the volcanic bombs were re-deposited
during the early Maastrichtian. Thus, the volcanics found at Răchitova have at least two origins: one type is related to an
explosive synsedimentary volcanic activity, and the other type is represented by older andesitic/dacitic bombs, which most
probably originate from a volcanic centre situated in the Haţeg region. 相似文献
987.
Piotr Weckwerth Krzysztof Przegiętka Alicja Chruścińska Barbara Woronko Hubert L. Oczkowski 《Geochronometria》2011,38(4):397-412
The deposits of the Toruń Basin are dominated by a few-metre thick sand series which fill up buried valley-like depressions.
In many cases they underlie the Weichselian till which builds up the ice marginal streamway (pradolina) terraces or they are
exposed at the basin slopes. As the results of the geological and sedimentological studies, as well as of the dating of the
deposits at the sites in the Toruń Basin indicate, the deposits include two fluvial series accumulated before the advancement
of the Leszno Phase ice sheet, i.e. in Middle Weichselian and at the beginning of Late Weichselian. The oldest fluvial series
connected with the Saalian Glaciation was found at the mouth section of the Drwęca Valley. The fluvial system of the Toruń
Basin during Middle Weichselian and at the beginning of Late Weichselian developed in two phases of the sand-bed braided river.
During the first one the river channel were dominated by large mid-riverbed sandbars, while during the second phase the water
flow was smaller and, as a result, low transverse sandbars and two-dimensional dunes developed. Other active river channel
also showed low-energy flows, more intensive meandering than in the case of the braided rivers, as well as sandy side-bars.
Analysis of the rounding and frosting of the quartz grains indicate that the studied series of the Weichselian sandy deposits
represent alluvia of a river which were fed from two diverse sources. The first one might have represented the alluvia of
a warm river which transformed its load, while the other one might have mainly carried the underlying Quaternary deposits. 相似文献
988.
989.
P. Morthekai Mayank Jain Pedro P. Cunha José M. Azevedo Ashok K. Singhvi 《Geochronometria》2011,38(3):223-230
The use of feldspar for luminescence dating has been restricted because of anomalous fading. This has made its application
to several important geological problems such as volcanic terrains difficult. Presently, two correction procedures are used
to correct for anomalous fading. The present study tests these correction procedures using volcanic samples of known ages
spanning the time period of 400 ka to 2.2 Ma. These correction procedures provided grossly underestimated ages (up to 60%).
The possible causes for the underestimation are discussed. 相似文献
990.
Reza Sohbati Andrew S. Murray Mayank Jain Jan-Pieter Buylaert Kristina J. Thomsen 《Geochronometria》2011,38(3):249-258
There are many examples of buried rock surfaces whose age is of interest to geologists and archaeologists. Luminescence dating
is a potential method which can be applied to dating such surfaces; as part of a research project which aims to develop such
an approach, the degree of resetting of OSL signals in grains and slices from five different cobbles/boulders collected from
a modern beach is investigated. All the rock surfaces are presumed to have been exposed to daylight for a prolonged period
of time (weeks to years). Feldspar was identified as the preferred dosimeter because quartz extracts were insensitive. Dose
recovery tests using solar simulator and IR diodes on both K-feldspar grains and solid slices taken from the inner parts of
the rocks are discussed. Preheat plateau results using surface grains and slices show that significant thermal transfer in
naturally bleached samples can be avoided by keeping preheat temperatures low. Equivalent doses from surface K-feldspar grains
were highly scattered and much larger than expected (0.02 Gy to >100 Gy), while solid surface slices gave more reproducible
small doses (mean = 0.17±0.02 Gy, n = 32). Neither crushing nor partial bleaching were found to be responsible for the large
scattered doses from grains, nor did the inevitable contribution from Na-feldspar to the signal from solid slices explain
the improved reproducibility in the slices. By modelling the increase of luminescence signal with distance into the rock surface,
attenuation factors were derived for two samples. These indicate that, for instance, bleaching at a depth of 2 mm into these
samples occurs at about ∼28% of the rate at the surface. We conclude that it should be possible to derive meaningful burial
doses of >1 Gy from such cobbles; younger samples would probably require a correction for incomplete bleaching. 相似文献