Annual Report 2011-2012 - Birbal Sahni Institute of Palaeobotany

EBIRBAL SAHNI INSTITUT
1946
OF PALAEOBOTANY
Annual Report 2011-2012
Project—Late Pleistocene palynochronostratigraphy
in north-eastern part of Cauvery Delta:
Implication in palaeoclimatic sea-level studies
(Sponsored by DST, New Delhi, No. SR/S4/ES-264/2007,
dated 30.09.2008)
Palynological, geochemical and fresh water
thecamoebian study of 5 sediment cores (2-5 m) from
Pichavaram estuary, TSpettai and Coleroon estuary is
continued which show 2 major phases of climate and
relative sea level changes (Phase I- ~5.0-2.0 kyrs:
increased diversity of mangroves, strengthened monsoon;
Phase II- ~since1.0 kyrs: low diversity of mangroves,
weakened monsoon) since ~5000 kyrs. The mangroves
in Pichavaram estuary has existed since ~3500 kyrs
revealing either subsidence or no delta progradation during
this period. However, the evidence of mangroves and
other marine forms show middle Holocene (5-6 kyrs)
shoreline extending 12-20 km inland from the present
estuary. These changes are attributed to deltaic
progradation induced by fall in relative sea level since
then. During the last millennium the deterioration in the
qualitative and quantitative palynological result from
different sites in the studied area is perhaps due to
estuarine configurational changes enhanced by
geomorphology, climate and anthropogenic pressure. In
addition, 52 river bed samples are collected along the
coastal areas in north-eastern Cauvery delta during the
field work.
Revised and finalized a manuscript on ‘Upper
Pennsylvanian lycopsids from interglacial taphoflora of
Itararé Group, Paraná Basin, Brazil’. The Pennsylvanian
lycopods of the Itararé Group are represented by diverse
megafossils, megaspores and microspores. The lycopsid
megafossils are described from the third interglacial level
of the palaeofloristic succession of the Itararé Group in
the northeastern border of the Paraná Basin, from the
type locality Volpe ranch, in Monte Mor municipality, SP.
The megafossils belong to the taxa Bumbudendron
millani, Bumbudendron cf. B. paganzianum,
Brasilodendron pedroanum, Brasilodendron sp.,
Leptophloeum cf. L. sanctae-helenae, and
Cyclodendron sp. The diversity and abundance of the
megafossils (sometimes forming coal beds in a glacial
context) indicates climatic ameliorations of an interglacial
phase of the “time Itararé”. They represent
palaeoecological hydrohygrophyllous communities of a
fluviatile-lacustrine depositional environment. The
biostratigraphical distribution of these taxa and their
association with Paranocladus, Ginkgophyllum and
Buriadia suggests a palaeofloristic correlation with the
Krauselcladus - Asterotheca Phytozone of northwestern
Argentinean palaeofloristic zonation. The lycophytic
megaspores recorded earlier from this level suggest a
diachronic correlation with the Permian Talchir and
Karharbari associations of Indian Gondwanan flora.
Comparison with late Paleozoic lycopsids and associated
megaspores of Argentina and India are in consonance
with the modern studies aiming to achieve knowledge of
Gondwana biostratigraphy in a wider perspective. Also
finalized a manuscript on ‘Pennsylvanian megaspores
from northeastern border of the Paraná Basin, Brazil:
Correlation with Indian Gondwana megaspores’.
Rajni Tewari (with Sandra E. Mune &
Mary E.C. Bernardes-de-Oliveira)
A manuscript on ‘Stratigraphic ranges of
dinoflagellate cysts from Cretaceous petroliferous basins
of India and Brazil’ has been finalized.
1. Rhizophora apiculata, 2. Rhizophora mucronata,
3. Sonneratia apetala, 4. Sonneratia caseolaris, 5. Avicennia
marina, 6. Excoecaria agallocha
48
Anjum Farooqui & Jyoti Srivastava
Project—Palaeobotanical studies on Indian and
Brazilian sedimentary basins with special reference
to marine dinoflagellate cysts, Gondwana flora and
their applications (Sponsored by DST, New Delhi, No.
DST/INT/Brazil/RPO-24/2007, dated 22.01.2009 &
CNPq, Brazil)
N.C. Mehrotra & Rajni Tewari (with Mitsuru Arai, Maria
Judite Garcia & Mary E.C. Bernardes-de-Oliveira
Finalized the paper on Monte Mor locality of Parana
Basin, Brazil and submitted. Palynological contents of the
Monte Mor taphoflora was restudied in surface samples
from the upper and lower levels of the coal beds and its
interval palynozone position has been reinterpreted and
revised. On the basis of presence of Crucisaccites
monoletus, Divarisaccus spp., Faunipollenites
(=Protohaploxypinus) amplus, Faunipollenites sp.,
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