Arctic Gas Hydrates: Physical, Environmental and Natural Hazard Aspects
November 14-15, 2005
Lamont Hall
Lamont-Doherty Earth Observatory
Palisades, NY
Organizers: Jim Cochran and Alberto Malinverno
List of Participants
Del Bohnenstiehl
Dale Chayes
Jim Cochran
Ann Cook
Nathan Bangs
Margo Edwards
Dave Goldberg
Jocelyn Grozic
Gilles Guerin
Patrick Hart
Dennis Hayes
Sean Higgins
Bob Kleinberg
Tom Lorenson
Alberto Malinverno
Kate Moran
Mladen Nedimovic
Kori Newman
Frank Nitsche
Matt O’Regan
Charlie Paull
Stephanie Pfirman
Michael Purdy
Dan Quoidbach
Golam Sarker
Taro Takahashi
Jeff Weissel
LDEO
LDEO
LDEO
LDEO
UTIG
SOEST
LDEO
U. of Calgary
LDEO
USGS
LDEO
LDEO
Schlumberger
USGS
LDEO
URI
LDEO
LDEO
LDEO
URI
MBARI
Barnard
LDEO
LDEO
LDEO
LDEO
LDEO
del@ldeo.columbia.edu
dale@ldeo.columbia.edu
jrc@ldeo.columbia.edu
acook@ldeo.columbia.edu
nathan@utig.ig.utexas.edu
margo@soest.hawaii.edu
goldberg@ldeo.columbia.edu
jgrozic@ucalgary.ca
guerin@ldeo.columbia.edu
hart@usgs.gov
deph@ldeo.columbia.edu
sean@ldeo.columbia.edu
kleinberg@slb.com
tlorenson@usgs.gov
alberto@ldeo.columbia.edu
kate.moran@uri.edu
mladen@ldeo.columbia.edu
knewman@ldeo.columbia.edu
fnitsche@ldeo.columbia.edu
oregan@gso.uri.edu
paull@mbari.org
spfirman@barnard.edu
mpurdy@ldeo.columbia.edu
daniel@ldeo.columbia.edu
sarker@ldeo.columbia.edu
taka@ldeo.columbia.edu
jeffw@ldeo.columbia.edu
Workshop Summary
On November 14 and 15 we convened a workshop on Arctic gas hydrates sponsored by
the LDEO Laboratory for Ocean Drilling, Observation, and Sampling (LODOS). The
goal of the workshop was to identify open scientific problems related to gas hydrates
along the US/Canada Beaufort Sea margin and to generate proposals for marine
geological and geophysical exploration and for drilling.
Presentations. The workshop started with a series of presentations to cover topics of
general interest:
- Margo Edwards: Marine geology of the Beaufort margin
- Tom Lorenson, Pat Hart: Gas hydrate studies of the Beaufort margin
- Charlie Paull: Gas hydrate studies of the offshore Mackenzie delta
- Nathan Bangs: Using seismic data to extrapolate gas hydrate physical properties
away from wells
- Jocelyn Grozic: Gas hydrates and slope stability
- Kate Moran: Arctic climate studies and Arctic drilling
- Dale Chayes: Logistical and permitting issues involved with marine work in the
Arctic
- Alberto Malinverno: Goals and preliminary results of Cascadia IODP Exp. 311.
(Scott Dallimore was also scheduled to talk about the Mallik well studies of gas hydrates
and permafrost, but had to cancel due to illness).
Science discussion. A scientific discussion followed the presentations. The focus of this
discussion was on the current state of knowledge, outstanding scientific problems, and
how and where to address them. We started from a list of open problems:
- Gas hydrate distribution,
- Climate change,
- Slope stability,
- Stratigraphy of the Arctic margin,
- Arctic basin evolution.
The goal of the discussion was to develop hypotheses that could be tested by marine
surveying and drilling. The discussion concentrated on a few key topics.
Transition between land/shelf and marine gas hydrates. In the Arctic environment, gas
hydrates are found in two settings: within or below permafrost on land and beneath
continental shelves that were above sea level during the last glacial (i.e., on both the
Mackenzie delta and the Alaskan Beaufort shelf), or on continental margins at depths
greater than about 300 m. Gas hydrates in permafrost are restricted to polar regions,
whereas they are found in continental margin sediments worldwide. In the Arctic,
thermodynamic stability predicts that the permafrost and the continental margin gas
hydrate domains should be separated by a gap. The Alaska/Canada Beaufort Sea margin
is an ideal setting to study the transition between permafrost and marine gas hydrates.
The focus of the study would be on mapping the gas hydrate distribution in the two
domains, testing the predictions of thermodynamic models, and determining the effects of
the last deglaciation.
Submarine slides along the Beaufort Sea continental slope. USGS seismic surveys have
shown clear evidence of landslides on the Beaufort Sea continental slope at depths
between 200-400 and 2000 m. The deformed sediments lay above a smooth bottomsimulating reflector, suggesting that overpressures due to gas hydrate dissociation may
have contributed to or caused the slides. The latest multichannel seismics in this area
were collected in the late 1970s, and new surveys may provide key data to test the gas
hydrate dissociation hypothesis for submarine slope instability. On the other hand, gas
hydrates and submarine slides are found on continental slopes worldwide, and there are
much easier areas where this kind of slope instability may be studied (e.g., the US East
coast).
Pingo-like features. “Pingo-like features” (PLFs) are mounds few tens of meters high and
wide that seem to be related to release of methane gas from the permafrost. Charlie Paull
reported that methane gas bubbling from an underwater PLF has been sampled on the
Mackenzie delta shelf. Charlie noted that at present these features are the only clearly
documented examples of methane escaping from permafrost. PLFs are found on the
Mackenzie delta both on land and on the shelf, and they are key features to study how
methane gas escapes from gas hydrates in Arctic regions.
Climate studies in the Mackenzie trough. It has been recently proposed that during
glacial periods the Mackenzie River transported large quantities of fresh water into the
Arctic basin by flowing next to the ice sheet in Canada. Kate Moran noted that an ideal
location to test this hypothesis is the Mackenzie trough, which contains up to 3500 m of
Plio-Pleistocene sediments. The high sedimentation rate would provide an ideal highresolution climate record for the Beaufort Sea region.
Proposal discussion. Following the science discussion, we concluded the workshop
with a session on potential topics for proposals. The goal of this discussion was to
develop objectives, strategies, and logistics for two field programs: a marine
geology/geophysics survey and an offshore drilling campaign. The proposals need
coordination because the survey proposal would provide the site survey data needed to
plan and carry out the drilling campaign.
Marine geology/geophysics proposal. The key problems to investigate would be the
distribution of permafrost and gas hydrates moving from shallow to deep water and the
relationship between gas hydrate distribution and slope instability. The transition
between gas hydrates on the shelf and on the continental slope could be imaged with
travel-time tomography using ocean bottom seismometers, similarly to the Hydrate Ridge
study presented by Nathan Bangs. Data on gas hydrate distribution and slope instability
could be acquired by multichannel seismics, multibeam bathymetry, heat flow surveys,
and coring. These studies could be carried out along three major N-S transects that cross
the Beaufort Sea margin, starting from points near Barrow, Prudhoe Bay, and the
MacKenzie delta. These surveys would provide data for siting cabled Arctic
observatories and for the drilling proposals described in the next section. Jim Cochran
and Alberto Malinverno will work on a proposal to be submitted in 2006; Nathan Bangs,
Margo Edwards, Pat Hart, Tom Lorenson, Mladen Nedimovic, and Charlie Paull
expressed interest in participating.
Drilling proposals. Charlie Paull and Scott Dallimore are planning to submit a proposal
to IODP for drilling PLFs in the Mackenzie delta shelf. The drilling could simply consist
of shallow holes on the top, the moat, and the flanks of PLFs or it could also include
deeper targets in a transect across the Mackenzie delta shelf. Besides this proposal, there
was also interest in a complementary proposal on characterizing the dynamic
environment where an exposed, cold shelf is warmed by transgression and the
consequences on permafrost and gas hydrates. Drilling could extend to the shelf edge
and beyond with shallow and deep boreholes. Extensions to this complementary program
may include drilling for a high resolution Holocene-Pleistocene climatic record in the
Mackenzie trough and Arctic observatories when available. Kate Moran offered to host
at the University of Rhode Island a meeting in the spring of 2006 to develop further this
complementary proposal.