At Coalsack Bluff (see image below), the Permian and Triassic
rocks are perfectly preserved with thick coal seams, remnants
of plant life and abundant fossils including the famous listrosauraus,
one of the loan survivors of this great catastrophe and are
amongst the discoveries that led to proof of the scientific
theory on ‘continental drift’. Coalsack Bluff
has also been used before as a base camp (e.g. Lewis Cliffs
icesheet) for the Antarctic meteorite collection program directed
by Dr. Ralph Harvey and is well suited for extended stays
in the field. Dr. Becker has participated in the meteorite-collecting
program and will discuss the flux of asteroids and cometary
debris to the Earth and their unique ‘extraterrestrial’
signatures in the rock record (see additional notes and pics.
coming soon). In our previous trip to Coalsack Bluff we were
surprised by the unique presevation of plants and organic
matter. We were also surprised to see significant areas near
the moraine where liquid water was flowing over the rocks
and underneath the icesheet. This is part of the reason that
we wanted to collect samples at Coal Sac bluff for the purpose
of understanding the distribution and transport of organics
that might reach the remote ice fields located adjacent to
our camp site.
As previously discussed, the Glossopterid leaves are amongst
the most common plant megafossils from the late Paleozoic
of Gondwana. Although they have been widely accepted as stratigraphic
indicators for the Permian, there have also been reports of
Glossopteris from the Lower Triassic of Tasmania, South Africa,
and India. The widespread geographic and stratigraphic range
of these leaf types may reflect the fact that the parent plants
were highly variable in habit and habitat. Per-mineralized
Glossopteris leaves are now known from Permian sites in Antarctica
and Australia. Some material from a silicified peat were collected
in the Shackleton Glacier area, central Transantarctic Mountains.
Based on lithology, the deposit is within the lower part of
the Fremouw Formation and has been considered to be Early
Triassic. The plants are petrified and therefore were studied
in thin sections. In addition to Glossopteris leaves, the
peat contains fragments of Vertebraria roots and small, unidentified
ovules, suggesting a very Late Permian age for this flora.
This material will be compared with known per-mineralized
floras that are slightly older, both from Antarctica and elsewhere
in Gondwana.
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| Figure 1: Coalsack Bluff,
Transantarctic Mountain Range, Antarctica, is a key locality
for the exploration of the Permian/Triassic mass extinction
event. Pictured here is a mound of coal where several
‘intact’ Lystrosaurus and fossilized plant
debris indicate a warmer wetter environment some 250 myrs
ago and further lending support to the theory of ‘Continental
Drift’. |
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