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From: Dan Richter (1:317/3)
To: All
Date: Fri, 18.09.20 13:00
ES Picture of the Day 18 2020
EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes
and phenomena which shape our planet and our lives. EPOD will collect and
archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


EPOD 20th - Calcite Crystals and Microbial Activity Within the Earth's
Crust

September 18, 2020

Press release Deep biosphere (1)

We’re celebrating 20 years of Earth Science Picture of the Day during
the month of September! Today’s photo features a popular EPOD from the
past. Thanks to all of our followers (on the blog, Facebook, Instagram
and Twitter) for supporting us. Thanks also to all of you who’ve
submitted your photos. We’re most appreciative. This EPOD was
originally published May 18, 2017.

Photographer: Henrik Drake
Summary Author: Henrik Drake

May 2017 Viewers' Choice The photo above features calcite
crystals precipitated in response to microbial activity deep within
the Earth's crust -- shown in fractured granitic rock in Sweden.
These crystals (about 5 mm in height) act to provide an archive for
tracking ancient microbial activity. The tweezers are included for
scale.

Methane-munching microbes, an analog for extraterrestrial life,
have been living in the deep biosphere for some 400 million years.
The knowledge about ancient life in the environment deep under our feet
is extremely scarce. In numerous cracks down to depths of 1700 m (5,577
ft) that have been partly sealed by crystals growing within them, an
international team of researchers led by Dr. Henrik Drake from
Linnaeus University, Sweden, have traced fundamental, ancient
microbial processes, including the production and consumption of the
greenhouse gas, methane. This is thus far the most extensive study on
ancient microbial activity in the continental crust, and findings
suggest that microbial methane formation and consumption are widespread
in the bedrock here.

This new knowledge of a deep source and sink for methane calls for a
re-evaluation of the carbon cycling within the vast continental
crust and may even be significant in a long-term global warming
perspective. Dr. Christine Heim of the University of Göttingen,
Germany, a co-author of the study, states that it's intriguing to find
biomarkers of ancient organic remains having surface origins (land
plants) preserved within calcite at such great depth. The nutrient
source for the microbes at least partly seems to have been coming from
the surface. This connection to the surface biosphere may explain why
the marks of microbial activity abruptly disappear at around 700 to 800
m in depth. So in essence, cracks in the Earth's crust and on other
planets, believed to be omnipresent, may be the perfect graveyards for
past biologic activities.

Photo Details: Camera: SONY DSC-RX10; Lens: 24-200mm F2.8; Focal
Length: 8.8mm (35mm equivalent: 24mm); Aperture: ƒ/2.8; Exposure Time:
0.017 s (1/60); ISO equiv: 125; Software: Adobe Photoshop Lightroom 6.8
(Windows).

Related EPODs

EPOD 20th - Calcite Crystals and Microbial Activity Within the
Earth's Crust EPOD 20th - Hollister Offset EPOD 20th - Anatahan
Eruption of May 11 Reynisfjara Beach, Iceland Color in Opals
Encore - Folded Rock on the Portuguese Vicentine Coast
More...

Geology Links

* Earthquakes
* Geologic Time
* Geomagnetism
* General Dictionary of Geology
* Mineral and Locality Database
* Mohs Scale of Mineral Hardness
* This Dynamic Earth
* USGS
* USGS Ask a Geologist
* USGS/NPS Geologic Glossary
* USGS Volcano Hazards Program

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

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