ARCHEAN TECTONICS

Since the late 1960's when plate tectonics was first widely accepted, geologists have long considered how far back in Earth's history plate tectonic processes operated. Until the late 1980's, many geologists considered that plate tectonic activity has only operated in the past 1 Ga. Since then, however, new discoveries have pushed back the envelope such that some geologists believe tectonic activity has occurred since the Late Archean. However, this is a matter of continued dispute and is currently unresolved.

 

Evidence for modern plate tectonic activity may be found in:

ophiolites- slices of ocean crust thrust onto the edge of continents

orogenic plutons- identification and dating of collisional granitic plutons.

Greenstone-Granulite Belts- interpreted as sites of former arcs and back arc basins.

 

                    OPHIOLITE STRATIGRAPHY

 

http://volcano.und.nodak.edu/vwdocs/vw_hyperexchange/ophiolites.html

   

                                        OPHIOLITES: MODES OF EMPLACEMENT

                               

http://volcano.und.nodak.edu/vwdocs/vw_hyperexchange/ophiolites.html

Water discovered beyond our solar system: July 2001

http://origins.jpl.nasa.gov/library/extrasolar/071101-a.html

Go To: ARCHEAN ASSIGNMENT