It's pretty much not a crater, the maps indicate no topography...

It's pretty much not a crater, the maps indicate no topography and it's Hot Copper interpretation at it's finest. Crater indicates a meteor impact or pre-existing volcano, or even a basin surrounded by mountains. Which the area is none of these.

Brazil has only 5 extinct major Volcanic sites, with the exploration area not being one of the Volcanoes. Majority of Volcanoes in South America are on the opposite side near Chile and Peru and stick to the major fault lines, there are some along the coast line of Brazil but are few and far between.

The image/difference in colouration is more due to whether it's been logged/cleared and the elevation dictating tree cover/plant growth. Majority of the darker green patches indicate a current running creek or river system.

There is a actually a system of mountains and valleys with a pattern more akin to a spread hand/fingers. In some instances these even spread out into more of a plateau of rolling hills.

Therefore there are hits in some valleys and not others/at different points within the same valley.