Organisational Structure - Birbal Sahni Institute of Palaeobotany

Birbal Sahni Institute of Palaeobotany
A total of 160 samples were processed in the
Radiocarbon Lab during the year, of these 152 were
dated. The routine dating has been continued using
Quantulus Liquid Scintillation Counter. The spectral
quench parameter measured using the internal
standard of the Quantutlus system is being used
regularly to correct counting efficiency due to self
quenching while calculating results. The motor unit
for vertical movement of the sample in the counting
chamber in the Quantulus became defective. This part
was procured and replaced at the end of November,
but the counting of samples was continued using the
less sensitive Rackbeta unit. Dating of high counting
samples is being carried out using Rackbeta system.
Efficiency correction for counting due to selfquenching
has also been carried out in the same
manner as in Quantulus system. Nine different kinds
of samples (carbonates, cellulose, barley, etc.) were
dated as a part of 4 th International Radiocarbon intercomparison
measurements conducted by University
of Glasgow (UK). The results agree very well with
measurements carried out at 83 laboratories world
over.
A peat sample (depth at 80 cm) from Kukrail
was dated for reconstruction of climate and vegetation
history around Lucknow. The age at was found to be
100 ±90 Yr. BP showing a high sedimentation rate.
Deeper samples are needed to infer the past vegetation
changes. Organic mud samples from Jarbokho (at 90
cm), Sidhi District and Barkullah (at 25 cm), Sahdol
District were dated (Jarbokho- 1360 ±90 YBP,
Barkullah- 3020 ±90 YBP) for chronological
reconstruction of vegetation and climate in different
regions of MP. Organic mud samples (130-150 cm)
from Dongar Sarbar, Sahdol District were dated (9470
±130 YBP) to reconstruct the temporal and spatial
distribution of tropical deciduous forest in central
India. Silty clay samples (at 4.0 m) from Dokriani
Bamak Glacier, Uttarkashi were dated (9050 ± 40
YBP) for the reconstruction of climatic changes
around that region and to link glacial fluctuations in
relation to 14 C dates. Carbonaceous sediment samples
from Bhojbas, Gangotri was also dated to understand
the climatic changes vis-à-vis glacial fluctuations.
The sample at 0.50-0.54 m depth in the profile dates
to 5990 ±120 YBP and the one at 1.20-1.24 m depth
dates to 8730 ±170 YBP. Interpretation of glacial
fluctuations on the basis of the palynological,
chemical and age data are being finalised.
Carbonaceous samples from Sukha Tal, Nainital were
dated to reconstruct the palaeovegetation and climate
of the area. The age at depth 230-235 cm works out
to 8260 ±170 YBP and at depth 335-340 cm it is
3790 ±110 YBP.
One Carbonaceous sediment sample (at 28.96 m)
from Mansar Lake, J&K was dated (8530 ±130 YBP)
for reconstruction of environment change with time
of that region. Carbonaceous clay samples from
Humayun’s Tomb, New Delhi was also dated. Dating
of carbonaceous samples (at 1.0 m depth) from
Sulurpet (AP) was undertaken to infer the chronology
of Holocene sea level and climatic changes, the age
is found to be 2310 ±140 YBP. Peat samples (at 3.0
m) from Kasredinilam, Sulurpet was also dated (4800
±180 YBP) to study the neotectonic movement in
the area and the data are being correlated with Pulicat
Lake and other East Coast regions. Peats (141-145
cm) from Adyar, Chennai was also dated (16680 ±280
YBP) to derive the history of mangrove vegetation
during Late Quaternary. Peats (1.25-1.35 m) from
Siro, Arunachal Pradesh was dated (>40,000 YBP)
to study the climatic changes in eastern Himalayas.
Carbonaceous samples (at 21-60 cm depth) from Zub
Lake, East Antarctica were dated (1310 ±140 YBP)
to understand the past climate of the region. Charcoal
sample (at depth 2.75 m) from Dadupur, Lucknow
was dated (3380 ±160 YBP) to understand the ancient
plant economy from Pre-historic and proto-historic
sites.
G. Rajagopalan
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