Extreme Environments - Hydrothermal settings for early life on Earth (an...
Δημοσιεύτηκε στις 17 Ιουλ 2015
It
is well known that New Zealand hosts spectacular hot-springs associated
with a live super-volcano. Less well known is that these geothermal
systems are rapidly mineralizing, entombing within silica a biota
adapted to high temperatures, and thus serving as an extreme environment
analog in the continuing search for the earliest signs of life on Earth
and potentially other planets, such as Mars. This hypothesis stems from
the following observations – the deepest roots of today’s “Tree of
Life” constitute heat-loving microbes in hot springs; some Precambrian
settings for early life were silica-rich and hydrothermally influenced;
and siliceous deposits recently found by Martian rover Spirit are
interpreted as hot-spring related.
The problem in trying to peer
back into “deep time” on Earth is that the very old rocks which may
contain the earliest traces of life also tend to be very “beaten up” by
later geological events. It can be difficult to prove both biogenicity
and original environmental setting in altered rocks billions of years
old. Hence, Kathleen Campbell’s research examines siliceous hot-spring
deposits to track the integrity of their fossil preservation through
time. This method allows us to follow microbes as they “turn to stone”
and to examine their history far back into the geological record,
thereby fine-tuning studies on the recognition of early terrestrial
life. The research has led to discovery of giant, Yellowstone-style,
paleo-geothermal systems in the Late Jurassic (150-million-year-old) of
Patagonia, Argentina. It also has confirmed hydrothermal signatures in
fossil microbe-rich, 3.33 billion-year-old shallow marine rocks of South
Africa.
is well known that New Zealand hosts spectacular hot-springs associated
with a live super-volcano. Less well known is that these geothermal
systems are rapidly mineralizing, entombing within silica a biota
adapted to high temperatures, and thus serving as an extreme environment
analog in the continuing search for the earliest signs of life on Earth
and potentially other planets, such as Mars. This hypothesis stems from
the following observations – the deepest roots of today’s “Tree of
Life” constitute heat-loving microbes in hot springs; some Precambrian
settings for early life were silica-rich and hydrothermally influenced;
and siliceous deposits recently found by Martian rover Spirit are
interpreted as hot-spring related.
The problem in trying to peer
back into “deep time” on Earth is that the very old rocks which may
contain the earliest traces of life also tend to be very “beaten up” by
later geological events. It can be difficult to prove both biogenicity
and original environmental setting in altered rocks billions of years
old. Hence, Kathleen Campbell’s research examines siliceous hot-spring
deposits to track the integrity of their fossil preservation through
time. This method allows us to follow microbes as they “turn to stone”
and to examine their history far back into the geological record,
thereby fine-tuning studies on the recognition of early terrestrial
life. The research has led to discovery of giant, Yellowstone-style,
paleo-geothermal systems in the Late Jurassic (150-million-year-old) of
Patagonia, Argentina. It also has confirmed hydrothermal signatures in
fossil microbe-rich, 3.33 billion-year-old shallow marine rocks of South
Africa.
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