I cannot determine the problem from these pictures. More information is needed such as how much of the tree is affected, recent weather conditions, picture of entire tree and entire leaf.  One possibility would be Oak anthracnose. Oak anthracnose is foliage fungal disease that is disfiguring, but not fatal, to the black oak tree. This fungal disease develops in tree debris that lies around the black oak tree. During the wet and warm spring months, the fungal spores are transported on the foliage of the black oak by wind and rain. This fungus then infects the foliage of the tree with symptoms appearing mostly towards the bottom of the tree, according to University of Minnesota Cooperative Extension. Infected black oak trees develop random spots and blotches on its leaves. Infected foliage also experiences curling and discoloration. The disease is less invasive if the tree is otherwise healthy. To avoid and control the disease, fertilize the tree regularly to keep it growing vigorously. Severely infected trees can be treated with a series of cooper-based fungicidal sprays.

It would be best to have a qualified arborist look at the tree to determine what the problem is.  You could check with the MSU diagnostic lab:  http://www.pestid.msu.edu/  Samples can be sent to them for a charge.  This site will tell you how to send them in.

Other sites to check: http://homeguides.sfgate.com/diagnose-curled-brown-leaf-edges-oak-trees-49553.html

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/oak-problems.aspx

I hope this was helpful.  Feel free to contact us again if you have further questions.