1. ONTOLOGICAL REPRESENTATION OF RIFTS
Arijit Mitra and A.K. Sinha
Department of Geosciences
Virginia Tech

2. RIFTS
Rifts are fault-bounded elongate troughs, under or near which the entire thickness of the lithosphere has been reduced by extension during their formation.
Rifts form in many tectonic settings such as above mantle plumes and at all stages of the Wilson Cycle.

3. Significance of Rifts
Rifting of continents involves two principal geological processes - tectonism and magmatism, which reflect the strain-rate and temperature dependent processes of deformation and adiabatic decompression melting within the earth.
Continental extension and break up are fundamental to understanding the origin of ocean basins and the mechanics of plate tectonics - all ocean basins form as a result of continental extension.

4. Significance of Rifts
The fundamental geological processes that cause crustal extension - mantle convection, mantle plumes, opposing forces from slab pull and ridge push, and gravitational collapse.
Hence, the study of rifts will enable us to determine
- the original local and regional states of stress
- the spatial and temporal distribution and rate of strain
- the pressures and temperatures
- the physical and chemical properties of rocks and fluids involved
- heterogeneity of the continental lithosphere prior to rifting
- the pattern of mantle flow
- the extent & style of melt generation & emplacement

5. ONTOLOGY for RIFTS
Reference:
Sengor & Natal’in, 2001

6. RIFT-RELATED ROCKS IN THE MID-ATLANTIC TEST BED
Two main phases of rifting (extension) in the Appalachians
Cryogenian Magmatic Province
760 Ma
failed rifting event
divergent plate boundary rift without previous doming (k22)
Catoctin Volcanic Province
570 Ma
rifting event that led to the formation of Iapetus ocean & break-up of Rodinia
Geological data from these two geological provinces are part of the VIRGINIA TECH IGNEOUS ROCK DATABASE

7. GLOBAL DATABASES ON EXTENSION RELATED ROCKS
GEOROC
NAVDAT
PETDB
PETROS
USGS DDS 14 Geochronology Database
EarthRef

8. Conclusion
Integration of the above-mentioned databases and web-based access through high performance computing is envisioned as part of the GEON cyberinfrastructure initiative.
An ontology driven integration is vital since ontologies are used as a computational pathway for answering queries.

9. Conclusion
A spatial and temporal comparison of geological provinces improves our understanding of geological processes and provides fundamental information on the physical and chemical evolution of continents through time.
Rift environments represent continental-scale processes that involve extrusion of igneous rocks, evolution of sedimentary basins, extensional/compressive tectonism to metamorphism and leave a geophysical signature.
An ontological linking and integration of these multidisciplinary datasets will improve our understanding of complex dynamics of Earth systems.