By Afrocentrism I'm assuming you mean one who is African-minded, as opposed to the original definition of the word which, ironically, happened to gain its inception in the Western world by blacks who practiced it as an attempt to interpret Western civilization through the eyes of Africans--as best they could considering that many of them were unable to trace their roots to a specific African group--and to artificially recreate an African viewpoint (allbeit out of a necessity of the times, so I am not downing Afrocentrism) without in depth interaction with continental African communities and especially to recreate it specifically as a response to Western thought leaves the authenticity of Afrocentrism itself indefinitely more suspect than atheism could ever be.

So, for the sake of my argument I am going to assume you mean "Does one who considers themselves an Atheist truly understand and possess an African mentality with the ability to uphold African issues in as authentic a manner as possible?"

Well, as one that dislikes labels I believe that yes, it is possible to be an "African-centered atheist."
To my knowledge there is not a manual or Bible in which one must follow to become an African-minded individual, nor am I aware of any induction ceremonies.
I say this with a bit of sarcasm (sorry that's my style )

I am weary of people who assume that anything is and can only be one thing. There are many types and shades of blue....some are similar, and some are the antithesis of each other (bright vs dingy, light vs. dark, pastel vs. bold) but there is something about them that still makes them all the color blue.

You point out, as possible proof of your theory, that there are no founded African tribes that practice atheism. Well if you can show me an atheistic Western/European nation (either past or present) in which Atheism was the accepted societal belief (as opposed to the exception) steeped in tradition and embedded in the culture then I will accept your notion that the absence of an atheistic African tribe is unequivocal proof that atheism could only be a Western conception.

It's one thing to study (or Google) African groups and tribes, but it's another to know the range of complexities of the individuals of that community. Communal beliefs are not definitive, they change and evolve with each generation, and community members are not each prototypical of their community's majorities (be it beliefs, likes, dislikes etc). African communities and African peoples are just as complex as any other peoples. But it's more romantic (and practical in slavery times) to view Africans as a lump sum. One may view themselves as Afrocentric, but that does not make that person Afro-thentic.
In Baule culture there is a predominant belief in Animism and creationism which are accompanied by a rich array of cultural beliefs and practices.
One of these practices is the sacrificial killing of an animal. The men share the meat but the women are not allowed to eat the meat of a sacrificed animal.
Most women take this seriously and will go as far as refusing to touch the meat while preparing the food, lest they accidentally ingest it from contact of their hands to their mouth.
Cha but I've known women who would just as soon pick this meat from their husband's teeth and swallow it. There are people within this same village with varying degrees of belief in their traditions. It is not unusual for someone who speaks out against tradition to be labeled crazy, or ignored and accused of having dementia, so it is understandable that cynicism against the traditional beliefs is more quelled in African communities than it is in Western communitites.
Just because one's society does not allow atheism to be defined, or does not make it conducive for a person to openly identify as such within their community does not mean it is not "logically possible" for one to believe in such a way...which is why I created the thread I did insinuating that it is less acceptable within the Black community for someone to openly identify as Atheist.

The one thing I do agree with is that Western Society does make it more acceptable to identify as Atheist than other societies, but that doesn't mean it created Atheism or fostered it in an individual, otherwise we, who lived in the Western world, would all be Atheist.