Abstract:
The sediment deposits of northwestern
Tripura, northeast India, revealed the enhanced proximity to the marginal marine environments, forest
cover variations and anthropogenic infuences. We
infer the palaeo-vegetation and palaeo-environmental
conditions between 9900 and 1800 cal B.P. through a
1.80 m deep sediment profle, from the remote location of Charilam, Tripura, using biotic (fossil pollen)
and abiotic (mineral magnetism) proxies. The sediment profle recorded warm and humid conditions
between 8300 and 6200 cal B.P., which later shifted
towards less humid phase until 4900 cal B.P. The
lower part of the sediment profle provided evidence
of enhanced sea-level in this region, as manifested
by mangrove taxa found between 9900 and 4900 cal
B.P. But later, these taxa were minimal and thereafter,
diminished in the sediments during the Late Holocene (4100–1800 cal B.P.).The occurrence of fewer
tree taxa and dominance of larger grass pollen signify
the enhancement of anthropogenic activities in the
region, during the recent times. The shifts in mineral magnetic content towards fne-grained anti-ferrimagnetic hematite components, as exhibited by relatively
high Hard IRM, SIRM/ΧLF, ARM/SIRM ratio and
low S–ratio towards the end of the Middle Holocene, resonate with the climate variations concurrent
to the vegetation changes. These interpretations lead
to the perception of a reduction in the Indian Summer Monsoon (ISM) strength during the Late Middle
Holocene. The inception of anthropogenic activities
has also induced the changes in the vegetation cover,
leading to increased soil erosion and land-use changes
during the Late Holocene in the region, which are
well observed in the pollen and mineral magnetic
records. This study focuses on multi-proxy analyses
of the Holocene sediments in this part of northeast
India, which has no such previous records.
