I am going on an archaeolgical excavation in Argentina over the summer; is there any rainforest?

.that I could see, and is it easy to get to over a long weekend?

Answers:
Yes, you have both rainforest in the extreme Northeast (Misiones province) and cloud forest (yungas) in the Northwest (Jujuy, Salta, Tucumán). The National Park at Iguazú Falls is good, but the Parks at the extreme Northwest are not so organized. I do hope you have time to visit other great landscapes here!
When you get here, I recommend you this series of new guides to all the natural areas in Argentina:
Juan Carlos Chebez. "GUIA DE LAS RESERVAS NATURALES DE LA ARGENTINA". You should get Volume III, for Northeastern Argentina, but they're all very useful and updated with both biological and touristic information.
http://www.amazon.com/gp/product/9502410580/qid=1147119865/sr=1-7/ref=sr_1_7/102-5580649-7633706?s=books&v=glance&n=283155
Good luck!
-------------
Update: Sorry, I've just noticed that you wish to see places in a "long weekend". Well, distances are fairly long in Argentina, so in that case, the opportunity will depend on the locality where you'll be working. Where will you be?

Other answers:
Please, please, go to the Iguazu Falls National Park (It can be very, very hot, though).
you´d love it:
http://whc.unesco.org/en/list/355
http://www.traveltango.com.ar/english/arg/igr/igr_eng.htm

Please, please, go to the Iguazu Falls National Park (It can be very, very hot, though).
you´d love it:
http://whc.unesco.org/en/list/355
http://www.traveltango.com.ar/english/arg/igr/igr_eng.htm
Argentina only have mud and ice.

More Questions & Answers...