United States Meteorite Impact Craters

Only a tiny fraction of the scientific work that needs to be done on Earth's known impact craters has been accomplished, and only a small fraction of the planet's craters have been discovered.  Even more work remains to be done on other surfaces in the solar system.  With the following list of questions, topics, and references to examples of specific kinds of work, I hope to save others a bit of time and effort if they are beginning to consider the field from the perspective of a researcher.

The order of the topics in the list is somewhat arbitrary, though I've tried to place them more-or-less sequentially in a manner such that each informs the following: ie:  Prove there is a crater, describe its rough location, place it in time and in a contemporary geological setting, characterize the impactor, understand the geological and geographical setting at the time of impact, and so on.  The list is far from exhaustive, and will grow with time.

Crater confirmation - Is the structure a crater?

• field search for shatter cones
• mapping of shatter cones, breccia, and topographical disturbance
• field mapping of ejecta/glass/meteorites for very small craters
• instrumental identification of high pressure polymorphs
• drilling and core section analysis
• petrographic search for planar fractures (PFs), planar deformation features (PDFs), glass, and so on.
• instrumental identification of impactor components in melts

Crater Morphometry - What is the structure's physical shape and size?

• diameter, depth, rim and uplift height, depth and nature of fill or removal
• topographical results of weathering and decay
• dimensions of uplift or annular basin and associated faulting
• asymmetries and implications for impact angle or ejecta emplacement
• computation of likely impactor size/velocity
• volume of altered or displaced rock.

Context - What rocks were here and where have they moved to?

• regional geologic mapping
• crater structural mapping
• crater geological mapping

Impactites - How did impact alter the rocks?

• pre-impact rock units
• displacement of pre-impact rock units 
• petrology and petrography of pre- and post-impact-alteration rocks
• shock barometers
• grain-scale altertion of specific minerals
• evolution of new minerals by shock and heat

Other High Pressure Polymorphs and Non-diagnostic Shock Effects

• Twinning, kink banding, evolution of diamond, rutile, etc.

Historical / Paleo- Setting and Effects of the Impact: 

• geologic and geopgraphic setting at time of impact
• biological effects
• destructive radius of heat, seismic, wind blast, and shock
• marine or land impact

Crater age:

• conodonts or other biostratigraphic
• radioisotope studies
• paleomagnetic
• stratigraphic constraints on crater or ejecta

Characterizing the impactor: dimensions, type, velocity, vector

Surface crater mapping: GIS topography, faults and rock units, Morphology and topography?

Subsurface and Remote Studies

• gravity
• seismic profile
• drilling
• magnetic

Contribution to Global Understanding

• relation to other known craters in age, size, impactor type, target material, etc.
• identification of trends in global data sets
• projections of unidentified crater numbers.

Post-impact processes -

• crater degradation - burial/erosion
• geochemical changes to excavated or impact aletered materials
• hydrothermal processes
• mineralization of crater associated faults 
• resource concentration or potentials 
• regional changes to target rocks: dolomitization, displacement, metamorphism, tilting, etc.

There are also non-crater-specific studies - impact modelling, high pressure mineral phases, crater accumulation rates, crater to impactor scaling, morphology to impact energy scaling, morphology to rock type scaling, hypervelocity impact physics, extinctions studies.

And non-traditional cratering questions: effects of impacts in water and in air (meteors).

And of indirect changes: proximal and distal ejecta studies (sometimes without an associated crater), Ir anomalies, sperules and spherule beds, tsunamite and paleoseismic deposits.

Inferred impact risk and impact risk abatement.

Professional academic journals that have published substantial numbers of impact crater related articles:

• Meteoritics and Planetary Science
• Geology
• Journal of Geophyisical Research
• Geochimica et Cosmochimic Acta
• and so on...

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below this line are website development notes:

finish integrating basic bibliographies

search and integrate LPSC abstracts

fix location of Glasford

update and upgrade summary graphics

cross-link to Odale pages, eg: http://ottawa-rasc.ca/wiki/index.php?title=Odale_articles_Glover_Bluff