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Effects of asteroid
and comet impacts on habitats for lithophytic organisms—A synthesis
Charles S. COCKELL1*, Pascal LEE2, Paul BROADY3,
Darlene S. S. LIM2, Gordon R. OSINSKI4, John PARNELL5,
Christian KOEBERL6, Lauri PESONEN7, and Johanna
SALMINEN7
1Planetary and Space Sciences Research Institute, Open
University, Milton Keynes. MK7 6AA, UK
2NASA Ames Research Center, Moffett Field, California
94035–1000, USA
3School of Biological Sciences, University of Canterbury,
Private Bag 4800, Christchurch, New Zealand
4Canadian Space Agency, 6767 Route de l’Aeroport, Saint-Hubert,
Quebec, J3Y 8Y9, Canada
5Department of Geology, University of Aberdeen, Aberdeen, AB24
3UE, UK
6Department of Geological Sciences, University of Vienna,
Althanstrasse 14, A-1090 Vienna, Austria
7Division of Geophysics, Department of Physical Sciences,
University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland
*Corresponding author. E-mail:
c.s.cockell@open.ac.uk
Asteroid and comet impacts can have
a profound influence on the habitats available for
lithophytic microorganisms. Using evidence from the Haughton impact
structure, Nunavut, Canadian High Arctic, we describe the role of impacts
in influencing the nature of the lithophytic ecological niche.
Impact-induced increases in rock porosity and fracturing can result in the
formation of cryptoendolithic habitats. In some cases and depending upon
the target material, an increase in rock translucence can yield new
habitats for photosynthetic cryptoendoliths. Chasmoendolithic habitats are
associated with cracks and cavities connected to the surface of the rock
and are commonly increased in abundance as a result of impact bulking.
Chasmoendolithic habitats require less specific geological conditions than
are required for cryptoendolithic habitats, and their formation is likely
to be common to most impact events. Impact events are unlikely to have an
influence on epilithic and hypolithic habitats except in rare cases,
where, for example, the formation of impact glasses might yield new
hypolithic habitats. We present a synthetic understanding of the influence
of asteroid and comet impacts on the availability and characteristics of
rocky habitats for microorganisms.
Geological overview and cratering model for the Haughton impact
structure, Devon Island, Canadian High Arctic
Gordon R. OSINSKI1, 2*, Pascal LEE3, John G.
SPRAY2, John PARNELL4, Darlene S. S. LIM5,
Theodore E. BUNCH6, Charles S. COCKELL7, and Brian
GLASS5
1Canadian Space Agency, 6767 Route de l’Aeroport, Saint-Hubert,
QC J3Y 8Y9, Canada
2Planetary and Space Science Centre, Department of Geology,
University of New Brunswick, 2 Bailey Drive, Fredericton, NB E3B 5A3,
Canada
3Mars Institute, SETI Institute and NASA Ames Research Center,
MS 245-3 Moffett Field, California 94035–1000, USA
4Geofluids Research Group, Department of Geology and Petroleum
Geology, University of Aberdeen, Aberdeen, AB24 3UE, UK
5NASA Ames Research Center, MS 245-3 Moffett Field, California
94035–1000, USA
6Department of Geology, Bilby Research Center, Northern Arizona
University, Flagstaff, Arizona, USA
7Planetary and Space Sciences Research Institute, The Open
University, Milton Keynes, MK7 6AA, UK
*Corresponding author. E-mail:
gordon.osinski@space.gc.ca
The Haughton impact structure has
been the focus of systematic, multi-disciplinary field
and laboratory research activities over the past several years. Regional
geological mapping has
refined the sedimentary target stratigraphy and constrained the thickness
of the sedimentary sequence at the time of impact to
~1880 m. New 40Ar–39Ar
dates place the impact event at ~39
Ma, in the late Eocene. Haughton has an apparent crater diameter of
~23 km, with an estimated rim (final
crater) diameter of ~16 km. The
structure lacks a central topographic peak or peak ring, which is unusual
for craters of this size. Geological mapping and sampling reveals that a
series of different impactites are present at Haughton. The volumetrically
dominant crater-fill impact melt breccias contain a calciteanhydrite-silicate
glass groundmass, all of which have been shown to represent
impact-generated melt phases. These impactites are, therefore,
stratigraphically and genetically equivalent to coherent impact melt rocks
present in craters developed in crystalline targets. The crater-fill
impactites provided a heat source that drove a post-impact hydrothermal
system. During this time, Haughton would have represented a transient,
warm, wet microbial oasis. A subsequent episode of erosion, during which
time substantial amounts of impactites were removed, was followed by the
deposition of intra-crater lacustrine sediments of the Haughton Formation
during the Miocene. Present-day intracrater
lakes and ponds preserve a detailed paleoenvironmental record dating back
to the last glaciation in the High Arctic. Modern modification of the
landscape is dominated by seasonal regional glacial and niveal melting,
and local periglacial processes. The impact processing of target materials
improved the opportunities for colonization and has provided several
present-day habitats suitable for microbial life that otherwise do not
exist in the surrounding terrain.
Impactites of the Haughton impact
structure, Devon Island, Canadian High Arctic
Gordon R. OSINSKI1†*, John G. SPRAY1, and Pascal
LEE2
1Planetary and Space Science Centre, Department of Geology,
University of New Brunswick,
2 Bailey Drive, Fredericton, New Brunswick E3B 5A3, Canada
2Mars Institute, SETI Institute, and NASA Ames Research Center,
Moffett Field, California 94035–1000, USA
†Canadian Space Agency, 6767 Route de l’Aeroport, Saint-Hubert, Quebec,
J3Y 8Y9, Canada
*Corresponding author. E-mail:
osinski@lycos.com
Contrary to the previous
interpretation of a single allochthonous impactite lithology, combined
field, optical, and analytical scanning electron microscopy (SEM) studies
have revealed the
presence of a series of impactites at the Haughton impact structure. In
the crater interior, there is a consistent upward sequence from
parautochthonous target rocks overlain by parautochthonous lithic (monomict)
breccias, through allochthonous lithic (polymict) breccia, into pale grey
allochthonous impact melt breccias. The groundmass of the pale grey impact
melt breccias consists of microcrystalline calcite, silicate impact melt
glass, and anhydrite. Analytical data and microtextures indicate that
these phases represent a series of impact-generated melts that were molten
at the time of, and following, deposition. Impact melt glass clasts are
present in approximately half of the samples studied. Consideration of the
groundmass phases and impact glass clasts reveal that impactites of the
crater interior contain shock-melted sedimentary material from depths of
>920 to <1880 m in the preimpact target sequence.
Two principal impactites have been recognized in the near-surface crater
rim region of
Haughton. Pale yellow-brown allochthonous impact melt breccias and
megablocks are overlain by pale grey allochthonous impact melt breccias.
The former are derived from depths of >200 to <760 m and are interpreted
as remnants of the continuous ejecta blanket. The pale grey impact melt
breccias, although similar to the impact melt breccias of the crater
interior, are more carbonate-rich and do not appear to have incorporated
clasts from the crystalline basement. Thus, the spatial distribution of
the crater-fill impactites at Haughton, the stratigraphic succession from
target rocks to allochthonous impactites, the recognition of large volumes
of impact melt breccias, and their probable original volume are all
analogous to characteristics of coherent impact melt layers in
comparatively sized structures formed in crystalline targets.
Tectonics of complex crater formation as revealed by the Haughton
impact structure, Devon Island, Canadian High Arctic
Gordon R. OSINSKI1, 2†* and John G. SPRAY2
1Lunar and Planetary Laboratory, University of Arizona, 1629
East University Boulevard, Tucson, Arizona 85721–0092, USA
2Planetary and Space Science Centre, Department of Geology,
University of New Brunswick,
2 Bailey Drive, Fredericton, New Brunswick E3B 5A3, Canada
†Present address: Canadian Space Agency, 6767 Route de
l’Aeroport, Saint-Hubert, Quebec, J3Y 8Y9, Canada
*Corresponding author. E-mail:
osinski@lycos.com
The results of a systematic field
mapping campaign at the Haughton impact structure have
revealed new information about the tectonic evolution of mid-size complex
impact structures. These studies reveal that several structures are
generated during the initial compressive outward-directed growth of the
transient cavity during the excavation stage of crater formation: (1)
sub-vertical radial faults and fractures; (2) sub-horizontal bedding
parallel detachment faults; and (3) minor concentric faults and fractures.
Uplift of the transient cavity floor toward the end of the excavation
stage produces a central uplift. Compressional inward-directed deformation
results in the duplication of strata along thrust faults and folds. It is
notable that Haughton lacks a central topographic peak or peak ring. The
gravitational collapse of transient cavity walls involves the complex
interaction of a series of interconnected radial and concentric faults.
While the outermost concentric faults dip in toward the crater center, the
majority of the innermost faults at Haughton dip away from the center.
Complex interactions between an outward-directed collapsing central uplift
and inward collapsing crater walls during the final stages of crater
modification resulted in a structural ring of uplifted, intensely faulted
(sub-) vertical and/or overturned strata at a radial distance from the
crater center of ~5.0–6.5 km.
Converging flow during the collapse of transient cavity walls was
accommodated by the formation of several structures: (1) sub-vertical
radial faults and folds; (2) positive flower structures and chaotically
brecciated ridges; (3) rollover anticlines in the hanging-walls of major
listric faults; and (4) antithetic faults and crestal collapse grabens.
Oblique strike-slip (i.e., centripetal) movement along concentric faults
also accommodated strain during the final stages of readjustment during
the crater modification stage. It is clear that deformation during
collapse of the transient cavity walls at Haughton was brittle and
localized along discrete fault planes separating kilometer-size blocks.
A case
study of impact-induced hydrothermal activity: The Haughton impact
structure, Devon Island, Canadian High Arctic
Gordon R. OSINSKI1†*, Pascal LEE2, John PARNELL3,
John G. SPRAY4, and Martin BARON3
1Lunar and Planetary Laboratory, University of Arizona, 1629
East University Boulevard, Tucson, Arizona 85721–0092, USA
2SETI Institute/NASA Ames Research Center, MS 245-3 Moffett
Field, California 94035–1000, USA
3Geofluids Research Group, Department of Geology and Petroleum
Geology, University of Aberdeen, Aberdeen, AB24 3UE, UK
4Planetary and Space Science Centre, Department of Geology,
University of New Brunswick,
2 Bailey Drive, Fredericton, New Brunswick E3B 5A3, Canada
†Canadian Space Agency, 6767 Route de l’AČroport, Saint-Hubert, Quebec,
J3Y 8Y9, Canada
*Corresponding author. E-mail:
osinski@lycos.com
The well-preserved state and
excellent exposure at the 39 Ma Haughton impact structure,
23 km in diameter, allows a clearer picture to be made of the nature and
distribution of hydrothermal deposits within mid-size complex impact
craters. A moderate- to low-temperature hydrothermal system was generated
at Haughton by the interaction of groundwaters with the hot impact melt
breccias that filled the interior of the crater. Four distinct settings
and styles of hydrothermal mineralization are recognized at Haughton: a)
vugs and veins within the impact melt breccias, with an increase in
intensity of alteration towards the base; b) cementation of brecciated
lithologies in the interior of the central uplift; c) intense veining
around the heavily faulted and fractured outer margin of the central
uplift; and d) hydrothermal pipe structures or gossans and mineralization
along fault surfaces around the faulted crater rim. Each setting is
associated with a different suite of hydrothermal minerals that were
deposited at different stages in the development of the hydrothermal
system.
Minor, early quartz precipitation in the impact melt breccias was followed
by the deposition of calcite and marcasite within cavities and fractures,
plus minor celestite, barite, and fluorite. This occurred at temperatures
of at least 200 °C and down to ~100–120
°C. Hydrothermal circulation through the faulted crater rim with the
deposition of calcite, quartz, marcasite, and pyrite, occurred at similar
temperatures. Quartz mineralization within breccias of the interior of the
central uplift occurred in two distinct episodes (~250
down to ~90 °C, and <60 °C). With
continued cooling (<90 °C), calcite and quartz were precipitated in vugs
and veins within the impact melt breccias. Calcite veining around the
outer margin of the central uplift occurred at temperatures of
~150 °C down to <60 °C.
Mobilization of hydrocarbons from the country rocks occurred during
formation of the higher
temperature calcite veins (>80 °C). Appreciation of the structural
features of impact craters has
proven to be key to understanding the distribution of hydrothermal
deposits at Haughton.
Intra-crater sedimentary deposits
at the Haughton impact structure, Devon Island, Canadian High Arctic
Gordon R. OSINSKI1†* and Pascal LEE2
1Mars Institute, 980 Seymour Street, Suite 1306, Vancouver,
British Columbia V6B 1B5, Canada
2Mars Institute, SETI Institute, and NASA Ames Research Center,
Moffett Field, California 94035–1000, USA
†Present address: Canadian Space Agency, 6767 Route de
l’Aeroport, Saint-Hubert, QuČbec, J3Y 8Y9, Canada
*Corresponding author. E-mail:
osinski@lycos.com
Detailed field mapping has revealed
the presence of a series of intra-crater sedimentary
deposits within the interior of the Haughton impact structure, Devon
Island, Canadian High Arctic. Coarse-grained, well-sorted, pale gray
lithic sandstones (reworked impact melt breccias) unconformably overlie
pristine impact melt breccias and attest to an episode of erosion, during
which time significant quantities of impact melt breccias were removed.
The reworked impact melt breccias are, in turn, unconformably overlain by
paleolacustrine sediments of the Miocene Haughton Formation. Sediments of
the Haughton Formation were clearly derived from pre-impact lower
Paleozoic target rocks of the Allen Bay Formation, which form the crater
rim in the northern, western, and southern regions of the Haughton
structure. Collectively, these field relationships indicate that the
Haughton Formation was deposited up to several million years after the
formation of the Haughton crater and that they do not, therefore,
represent an immediate, post-impact crater lake deposit. This is
consistent with new isotopic dating of impactites from Haughton that
indicate an Eocene age for the impact event (Sherlock et al. 2005). In
addition, isolated deposits of post-Miocene intra-crater
glacigenic and fluvioglacial sediments were found lying unconformably over
remnants of the
Haughton Formation, impact melt breccias, and other pre-impact target rock
formations. These
deposits provide clear evidence for glaciation at the Haughton crater. The
wealth and complexity of geological and climatological information
preserved as intra-crater deposits at Haughton suggests that craters on
Mars with intra-crater sedimentary records might present us with similar
opportunities, but also possibly significant challenges.
Application of
organic geochemistry to detect signatures of organic matter in the
Haughton impact structure
John PARNELL1, Pascal LEE2, Gordon R. OSINSKI3,
and Charles S. COCKELL4
1Department of Geology and Petroleum Geology, University of
Aberdeen, Aberdeen AB24 3UE, UK
2SETI Institute/NASA Ames Research Center, MS 245-3, Moffett
Field, California 94035–1000, USA
3Department of Planetary Sciences, Lunar and Planetary
Laboratory, University of Arizona, Tucson, Arizona 85721–0077, USA
4British Antarctic Survey, High Cross, Madingley Road,
Cambridge CB3 OET, UK
*Corresponding author. E-mail:
j.parnell@abdn.ac.uk
Organic geochemistry applied to
samples of bedrock and surface sediment from the
Haughton impact structure detects a range of signatures representing the
impact event and the transfer of organic matter from the crater bedrock to
its erosion products. The bedrock dolomite contains hydrocarbon-bearing
fluid inclusions which were incorporated before the impact event.
Comparison of biomarker data from the hydrocarbons in samples inside and
outside of the crater show the thermal signature of an impact. The
occurrence of hydrocarbon inclusions in hydrothermal mineral samples shows
that organic matter was mobilized and migrated in the immediate aftermath
of the impact. The hydrocarbon signature was then transferred from bedrock
to the crater-fill lacustrine deposits and present-day sediments in the
crater, including wind-blown detritus in snow/ice. Separate signatures are
detected from modern microbial life in crater rock and sediment samples.
Signatures in Haughton
crater samples are readily detectable because they include hydrocarbons
generated by the burial of organic matter. This type of organic matter is
not expected in crater samples on other planets, but the Haughton data
show that, using very high resolution detection of organic compounds, any
signature of primitive life in the crater rocks could be transferred to
surface detritus and so extend the sampling medium.
Re-evaluating
the age of the Haughton impact event
Sarah C. SHERLOCK1*, Simon P. KELLEY1, John PARNELL2,
Paul GREEN3,
Pascal LEE4, Gordon R. OSINSKI5, and Charles S.
COCKELL6
1Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR),
Department of Earth Sciences, The Open University, Walton Hall, Milton
Keynes, MK7 6AA, UK
2Department of Geology and Petroleum Geology, College of
Physical Sciences, University of Aberdeen, Meston Building, King’s
College, Aberdeen, AB24 3UE, UK
3Geotrack International, 37 Melville Road, Brunswick West,
Victoria 3055, Australia
4Mars Institute, SETI Institute and NASA Ames Research Center,
MS 245-3, Moffett Field, California 94035–1000, USA
5Canadian Space Agency, 6767 Route de l’Aeroport, Saint-Hubert,
QC J3Y 8Y9, Canada
6Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR),
Planetary and Space Sciences Research Institute, The Open University,
Walton Hall, Milton Keynes, MK7 6AA, UK
*Corresponding author. E-mail:
s.sherlock@open.ac.uk
We have re-evaluated the published
age information for the Haughton impact structure,
which was believed to have formed ~23
Ma ago during the Miocene age, and report new Ar/Ar laser probe data from
shocked basement clasts. This reveals an Eocene age, which is at odds with
the published Miocene stratigraphic, apatite fission track and Ar/Ar data;
we discuss our new data within this context. We have found that the age of
the Haughton impact structure is ~39
Ma, which has implications for both crater recolonization models and
post-impact hydrothermal activity. Future work on the relationship between
flora and fauna within the crater, and others at high latitude, may
resolve this paradox.
Spaceborne
visible and thermal infrared lithologic mapping of impact-exposed
subsurface lithologies at the Haughton impact structure, Devon Island,
Canadian High Arctic: Applications to Mars
Livio L. TORNABENE1*, Jeffrey E. MOERSCH1, Gordon R.
OSINSKI2, Pascal LEE3, and Shawn P. WRIGHT4
1Department of Earth and Planetary Sciences, University of
Tennessee, Knoxville, Tennessee 37996–1410, USA
2Canadian Space Agency, John H. Chapman Space Centre, Longueuil,
Quebec J3Y 8Y9, Canada
3Mars Institute, SETI Institute and NASA Ames Research Center,
Moffett Field, California 94035, USA
4Department of Geological Sciences, Arizona State University,
Tempe, Arizona 85287–6305, USA
*Corresponding author. E-mail:
ltornabe@utk.edu
This study serves as a
proof-of-concept for the technique of using visible-near infrared
(VNIR), short-wavelength infrared (SWIR), and thermal infrared (TIR)
spectroscopic observations to map impact-exposed subsurface lithologies
and stratigraphy on Earth or Mars. The topmost layer, three subsurface
layers and undisturbed outcrops of the target sequence exposed just 10 km
to the northeast of the 23 km diameter Haughton impact structure (Devon
Island, Nunavut, Canada) were mapped as distinct spectral units using
Landsat 7 ETM+ (VNIR/SWIR) and ASTER (VNIR/SWIR/TIR) multispectral images.
Spectral mapping was accomplished by using standard image
contraststretching algorithms. Both spectral matching and deconvolution
algorithms were applied to imagederived ASTER TIR emissivity spectra using
spectra from a library of laboratory-measured spectra of minerals (Arizona
State University) and whole-rocks (Ward’s). These identifications were
made without the use of a priori knowledge from the field (i.e., a “blind”
analysis). The results from this analysis suggest a sequence of dolomitic
rock (in the crater rim), limestone (wall), gypsum-rich carbonate (floor),
and limestone again (central uplift). These matched compositions agree
with the lithologic units and the pre-impact stratigraphic sequence as
mapped during recent field studies of the
Haughton impact structure by Osinski et al. (2005a). Further conformation
of the identity of imagederived spectra was confirmed by matching these
spectra with laboratory-measured spectra of samples collected from
Haughton. The results from the “blind” remote sensing methods used here
suggest that these techniques can also be used to understand subsurface
lithologies on Mars, where ground truth knowledge may not be generally
available.
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