Annual Report 2011-2012 - Birbal Sahni Institute of Palaeobotany

EBIRBAL SAHNI INSTITUT
1946
OF PALAEOBOTANY
Annual Report 2011-2012
these sections are completed. Two distinct palynological
zones have been recognized on the abundance and
distribution of stratigraphically significant palynofossils in
the Hut Bay succession. The palynofloral assemblage is
also compared with other known Miocene palynofloral
assemblages. Analysis of the composition of this
assemblage depicts its close similarity with those recorded
from Inglis Island. Additionally, detailed morphotaxonomic
study of the recovered palynofossils from the measured
stratigraphic sections, viz. Phulri Nala section (Strait
Island), North-East Coast and Wreck point sections
(Henry Island) is completed. Samples from these sections
are very rich in diatoms and sillicoflagellates. The recovery
of palynofossils belonging to pteridophytic spores,
gymnosperm and angiosperm pollen is extremely poor in
all the sections. Biostratigraphic potential of those
recovered palynofossils is also assessed.
Palynological investigation of Long and Inglis
formations at Meetha Nala of the Havelock Island have
been completed. 21 genera with 37 species, varieties and
forms of diatoms have been identified. Predominant diatom
taxa of the assemblage are Actinoptychus undulatus,
Asterolampra punctifera, Coscinodiscus spp.,
Gramatophora maxima, Rossiella sp., Triceratium
gallapangense, etc. The distributional pattern of diatoms
in this stratigraphic sequence has been analyzed and
interpreted throwing light on its dating potential and
environment of deposition. On the basis of comparison of
the present assemblage with other diatom assemblages
known from Indian Tertiary sediments, a Middle Miocene
to Late Miocene age has been assigned to the sediments
of Long and Inglis formations in the present area of
investigation. A paper on the aspect is finalized. Besides,
carried out field work at Portblair, Havelock, Neil and its
adjoining areas of Andaman-Nicobar Islands, and
collected altogether 116 palynological samples from
several measured sections. Survey is carried out at several
localities to find out well exposed sections of Tertiary
rocks in these Islands for filling gaps in our earlier studies.
Samir Sarkar
Project 6.4:
Taxonomic analysis of calcareous algae from the Cenozoic sediments of Andaman-
Nicobar Basin and its implications on palaeogeography, palaeoecology and
palaeobathymetry
Coralline red algae and Halimedacean green algae
have been recorded from the Limestone unit of Hut Bay
(Little Andaman Island) belonging to Middle Miocene age.
Taphonomy and growth-form analysis of Coralline algae,
palaeodiversity of algal forms and benthic foraminifera
from the late Middle Miocene sediments of Hut Bay
Limestone have been done. Identification and statistical
analysis of the algal forms from the Car Nicobar Island
(Nicobar Group of Islands) based on thin sections have
been done on the samples collected from the Kakana
Limestone unit (Middle Pliocene Limestone outcropping
in the Car Nicobar Island). Facies characterization and
palaeoenvironmental significance of reef forming coralline
algal sediments from the Middle Pliocene of Car Nicobar
Island have been studied.
The expected achievements of the previous year
was to record calcareous algae from the Cenozoic
sediments of Andaman-Nicobar Basin and other potential
sedimentary basins of India for the reconstruction of algal
rich facies and to evaluate the role of algal assemblages
in palaeogeography, palaeoecology and palaeobathymetry.
In view of this calcareous algae have also been studied
from four samples and two distinct facies types have been
recognized in thin section analysis from the Umlatdoh
Limestone Member of the Shella Formation. Diversity,
growth-form analysis, taphonomy and palaeoecological
implications of Corallanicean Red Algae and
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Thalassiosira sp. (Dominant Diatom found)
from Havlock Island
Halimedacean Green Algae from the Prang Limestone
Formation of South Shillong Plateau have been studied.
Benthic and planktonic foraminifera from the Mio-
Pliocene sequence of Havelock Island (Andaman &
Nicobar Basin) have been isolated. Analyses and
Interpretation are in progress. In addition, a field trip is
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