White Paper Title: 
Co-registration of historical maps of Icelandic rift zones reveal changes in shallow crustal permeability and hydrothermal systematics in concert with local seismic and magmatic events: Implications for investigation of the R2K focus.

Daniel Curewitz (Syracuse Univ.) and Jeff Karson (Duke Univ.)

Preliminary co-registration of several generations of available geological data was carried out for the Hengill and Krafla hydrothermal fields along active rift zones of the Iceland plate boundary zone. Initial results indicate significant short-term and long-term changes in hydrothermal outflow locations, flow rates and styles, and hydrothermal fluid characteristics over short periods in concert with recorded earthquakes, dike intrusions, and fissure eruptions. Higher resolution, more detailed maps covering the time-periods in question are being collected for integration and analysis.

Initial results from the Hengill and Krafla geothermal areas covering a time-span of nearly 40 years at ~10 year intervals indicate the following:

1)    the surface expression of fault populations change in character very little, with the exception of local fault and fracture systems;

2)    there is evidence for significant changes in vent population locations over that same time period, with either older vents shifting location, or new vents opening and old vents closing;

3)    there are areas of high vent population density mapped over a 10-year span that are absent from both previous and later maps, and areas of little or no hydrothermal activity over that same 10-year span that host significant hydrothermal vent populations in both earlier and later maps;

4)    changes in vent (and/or vent field) temperature and flow rate, as well as vent eruptive style are similarly observed in successive map generations;

5)    significant local seismic and volcanological events (earthquakes, earthquake swarms, dike intrusions, eruptions, inflation/deflation) take place in intervening years between production of successive maps that are potential triggers for the observed changes.

Higher resolution maps of these hydrothermal systems, specifically maps that have been converted to GIS data objects containing detailed vent location and temperature, chemistry, and flow-rate data are being collated and collected for a more in-depth and detailed analysis.

There is significant potential for this type of analysis to be used to understand the interplay between tectonic activity, fault populations and hydrothermal outflow characteristics over very short time-scales. Along more intensively surveyed segments of the MOR, there may be potential for detailing similar temporal and spatial correlative relationships between short-term geological/geophysical events and the shallow architecture of the mid-ocean ridge crest.