Wanted (and some found): Geologic maps (formation contacts) of South America countries, for use in GIS

Here’s a good ol’ plea for help from the scientific community. As my questions to “the scientific community” via Academia.edu have gone unnoticed, I’m posting this out here to see if anyone else searching for the same thing has had any luck. I’m building a GIS (geographic information system) model to determine the possible biogeographic districbution of a genus through time. What I need for this, since the fossils are from South America, is a good geologic map, either of most of the continent or of the countries of Brazil, Argentina, Ecuador, and Peru. Hunting around online hasn’t shown me anything that I want to shell out a bunch of money for, site unseen, and I’m honestly trying to avoid having to scan paper maps and register them (additionally, I haven’t been able to access our worldwide collection of paper geologic maps recently). 1:500,000 or 1:100,000 would be great, but I’d even take 1:1,000,000 at this point. I need something with formational contacts so I can plot possible distributions. So that’s the challenge of the day: have any geologists in South America discovered a good source for this type of material? Would you be willing to share or trade? Drop me an email at one of the addresses on the right sidebar if you can help.


UPDATE 2011-08-15: I found (finally) an online version of the Geological Map of Brazil at 1:1,000,000 scale. Unfortunately it is only available in a viewer, broken up into small sections. Anyone know where I can download the full dataset, or at least that data for those sections? UPDATE 2011-08-15 1431: Thanks to Sidney Goveia over at Geosaber, I tracked down the Brazil data to Geobank, so here goes nothing! If you are using a Mac, make sure you extract the contents of the ZIP files using StuffIt Expander (if you have it) rather than Archive Utility, otherwise you don’t end up with a folder.


UPDATE 2011-08-16: You can download a formation-level geological map of Peru at the 1:1,000,000 scale from INGEMMET – the Instituto Geologico Minero Y Metalurgico. There are a few steps through the online viewer (note: this is the new viewer, so the following steps may not work the same), which may appear in Spanish at first but for some reason decided to reload partway through in English. If you want, you can try to figure out how to turn on the layer under the Map–>Geodatabase menu, but really when that menu comes up you want to click the Download/Descargas folder icon, then select the Geologia layer (SHP icon next to it). It also looks like you can download the data as a KML file for Google Earth. A structural layer (Dominios Estructurales) also looks available, and I checked out the radiometric date layer (Dataciones Radiometricas) as well, which could be useful. You might need to check the projection on the geologic map once you download it. I imported it to QGIS at first and it came up as WGS 84 (probably because of the existing project), but I dug around and figured out that it works as PSAD_1956_UTM_Zone_18S. Need a map key for formation symbols? You can download scans of the paper version of this map from here, one of which has the legend. If the correct map doesn’t come up at that link, click on “Ministerio de Energia y Minas. Instituto de Geologia y Mineria” so see the others. The symbology is different. An alternative large-scale (1:100,000) but low-quality set of maps is available here but will not easily go into GIS.